ABCC5; ATP-binding cassette, sub-family C (CFTR/MRP), member 5 (3q27)

Gene Summary

Gene:ABCC5; ATP-binding cassette, sub-family C (CFTR/MRP), member 5
Aliases: MRP5, SMRP, ABC33, MOATC, MOAT-C, pABC11, EST277145
Summary:The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions in the cellular export of its substrate, cyclic nucleotides. This export contributes to the degradation of phosphodiesterases and possibly an elimination pathway for cyclic nucleotides. Studies show that this protein provides resistance to thiopurine anticancer drugs, 6-mercatopurine and thioguanine, and the anti-HIV drug 9-(2-phosphonylmethoxyethyl)adenine. This protein may be involved in resistance to thiopurines in acute lymphoblastic leukemia and antiretroviral nucleoside analogs in HIV-infected patients. Alternative splicing of this gene has been detected; however, the complete sequence and translation initiation site is unclear. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:multidrug resistance-associated protein 5
Updated:14 December, 2014


What does this gene/protein do?
Show (18)

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 14 December 2014 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Down-Regulation
  • Proto-Oncogene Proteins
  • Chromosome 3
  • Carcinoma
  • Up-Regulation
  • Xeroderma Pigmentosum Group D Protein
  • Messenger RNA
  • ras Proteins
  • MicroRNAs
  • Oligonucleotide Array Sequence Analysis
  • Receptors, Cytoplasmic and Nuclear
  • Immunohistochemistry
  • ABCC5
  • Tumor Markers
  • Cancer Gene Expression Regulation
  • Squamous Cell Carcinoma
  • Mutation
  • Genes, MDR
  • Deoxycytidine
  • Pancreatic Cancer
  • Antimetabolites, Antineoplastic
  • Phytogenic Anticancer Agents
  • Breast Cancer
  • Doxorubicin
  • Drug Resistance
  • Lung Cancer
  • Multiple Drug Resistance
  • Base Sequence
  • ATP-Binding Cassette Transporters
  • Transcription Factors
  • Gene Expression Profiling
  • Antineoplastic Agents
  • Tumor Suppressor Proteins
  • Neoplasm Proteins
  • Multidrug Resistance-Associated Proteins
  • Gene Expression
  • Single Nucleotide Polymorphism
  • Non-Small Cell Lung Cancer
  • Neoadjuvant Therapy
  • Cisplatin
Tag cloud generated 14 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (1)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Breast CancerABCC5 and Breast Cancer View Publications6

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Related Links

Latest Publications: ABCC5 (cancer-related)

Noori-Daloii MR, Saffari M, Raoofian R, et al.
The multidrug resistance pumps are inhibited by silibinin and apoptosis induced in K562 and KCL22 leukemia cell lines.
Leuk Res. 2014; 38(5):575-80 [PubMed] Related Publications
Silibinin have been introduced for several years as a potent antioxidant in the field of nutraceuticals. Based on wide persuasive effects of this drug, we have decided to investigate the effects of silibinin on chronic myelogenous leukemia (CML) in vitro models, K562 and KCL22 cell lines. Lactate dehydrogenase (LDH) release, microculture tetrazolium test (MTT assay) and real-time PCR were employed to evaluate the effects of silibinin on cell cytotoxicity, cell proliferation and expression of various multidrug resistance genes in these cell lines, respectively. Our results have shown that presence of silibinin has inhibitory effects on cell proliferation of K562 and KCL22 cell lines. Also, our data indicated that silibinin, in a dose-dependent manner with applying no cytotoxic effects, inhibited cell proliferation and reduced mRNA expression levels of some transporter genes e.g. MDR1, MRP3, MRP2, MRP1, MRP5, MRP4, ABCG2, ABCB11, MRP6 and MRP7. The multifarious in vitro inhibitory effects of silibinin are in agreement with growing body of evidence that silibinin would be an efficient anticancer agent in order to be used in multi-target therapy to prevail the therapeutic hold backs against CML.

Related: Apoptosis Leukemia

Duong HQ, Yi YW, Kang HJ, et al.
Inhibition of NRF2 by PIK-75 augments sensitivity of pancreatic cancer cells to gemcitabine.
Int J Oncol. 2014; 44(3):959-69 [PubMed] Free Access to Full Article Related Publications
We describe the potential benefit of PIK-75 in combination of gemcitabine to treat pancreatic cancer in a preclinical mouse model. The effect of PIK-75 on the level and activity of NRF2 was characterized using various assays including reporter gene, quantitative PCR, DNA-binding and western blot analyses. Additionally, the combinatorial effect of PIK-75 and gemcitabine was evaluated in human pancreatic cancer cell lines and a xenograft model. PIK-75 reduced NRF2 protein levels and activity to regulate its target gene expression through proteasome-mediated degradation of NRF2 in human pancreatic cancer cell lines. PIK-75 also reduced the gemcitabine-induced NRF2 levels and the expression of its downstream target MRP5. Co-treatment of PIK-75 augmented the antitumor effect of gemcitabine both in vitro and in vivo. Our present study provides a strong mechanistic rationale to evaluate NRF2 targeting agents in combination with gemcitabine to treat pancreatic cancers.

Related: NFE2L2 gene Cancer of the Pancreas Pancreatic Cancer Gemcitabine

Furney SJ, Pedersen M, Gentien D, et al.
SF3B1 mutations are associated with alternative splicing in uveal melanoma.
Cancer Discov. 2013; 3(10):1122-9 [PubMed] Related Publications
UNLABELLED: Uveal melanoma, the most common eye malignancy, causes severe visual morbidity and is fatal in approximately 50% of patients. Primary uveal melanoma can be cured by surgery or radiotherapy, but the metastatic disease is treatment refractory. To understand comprehensively uveal melanoma genetics, we conducted single-nucleotide polymorphism arrays and whole-genome sequencing on 12 primary uveal melanomas. We observed only approximately 2,000 predicted somatic single-nucleotide variants per tumor and low levels of aneuploidy. We did not observe an ultraviolet radiation DNA damage signature, but identified SF3B1 mutations in three samples and a further 15 mutations in an extension cohort of 105 samples. SF3B1 mutations were associated with good prognosis and were rarely coincident with BAP1 mutations. SF3B1 encodes a component of the spliceosome, and RNA sequencing revealed that SF3B1 mutations were associated with differential alternative splicing of protein coding genes, including ABCC5 and UQCC, and of the long noncoding RNA CRNDE.
SIGNIFICANCE: Our data show that despite its dismal prognosis, uveal melanoma is a relatively simple genetic disease characterized by recurrent chromosomal losses and gains and a low mutational burden. We show that SF3B1 is recurrently mutated in uveal melanoma, and the mutations are associated with aberrant alternative splicing.

Related: Melanoma Ocular Melanoma IntraOcular Melanoma BAP1 gene

Benabbou N, Mirshahi P, Cadillon M, et al.
Hospicells promote upregulation of the ATP-binding cassette genes by insulin-like growth factor-I via the JAK2/STAT3 signaling pathway in an ovarian cancer cell line.
Int J Oncol. 2013; 43(3):685-94 [PubMed] Free Access to Full Article Related Publications
Interaction between tumor cells and their micro-environment has a crucial role in the development, progression and drug resistance of cancer. Our objective was to confirm the role of Hospicells, which are stromal cells from the cancer microenvironment, in drug resistance and tumor cell growth. We demonstrated that soluble factors secreted by Hospicells activate several genes and upregulate the JAK/STAT signaling pathway in ovarian cancer cell lines. Hospicells express all insulin-like growth factor (IGF) family as detected by gene array, RT-PCR, protein array and immunocytochemistry. While focusing attention on the microenvironment, we considered the role of IGF-I in proliferation and survival of ovarian cancer cells. Indeed, IGF-I is a major regulator of different stages of cancer development. We studied the effect of exogenously added IGF-I on the regulation of ATP-binding cassette (ABC) genes (MDR1, MRP1, MRP2, MRP3, MRP5 and BCRP) in the ovarian cancer cell line OVCAR3 and validated the results obtained using the IGF-IR antagonist picropodophyllin. IGF-I regulates the expression of ABC genes in OVCAR3 cells via the PI3-kinase, MEK and JAK2/STAT3 signaling pathways. The OVCAR3 cell line when co-cultured with Hospicells showed a marked degree of drug resistance. The drug resistance observed could be amplified with exogenous IGF-I. Addition of IGF-IR inhibitor, however, reduced the degree of resistance in these exposed cells. Cells that were treated with anticancer drugs and then exposed to IGF-I showed an increase in drug resistance and, thereby, an increase in cell survival. This observation indicates that drug resistance of OVCAR3 cells increases when there is synergy between OVCAR3 cells and Hospicells and it is amplified when IGF-I was exogenously added. In conclusion, inhibition of IGF-IR and targeting of the JAK2/STAT3 signaling pathway can be a target for ovarian cancer therapy.

Related: IGF1 JAK2 gene Ovarian Cancer IGF1R Signal Transduction

Wang H, Zhai Z, Li N, et al.
Steroidal saponin of Trillium tschonoskii. Reverses multidrug resistance of hepatocellular carcinoma.
Phytomedicine. 2013; 20(11):985-91 [PubMed] Related Publications
Combating with multidrug resistance (MDR) is a major part of hepatocellular carcinoma (HCC) chemotherapy. Steroidal saponin from Trillium tschonoskii (TTS) could be a potential weapon. We found TTS could reverse the MDR in HCC cells and significantly enhance chemosensitization. TTS inhibited HepG2 and R-HepG2 cells survival in a dose-dependent manner by 75% and 76%, respectively (p<0.01), as well as colony formation 77% and 81% (p<0.01). Moreover, TTS induced sensitization of R-HepG2 to anti-cancer drugs, indicated by significantly reduced IC50. On the other hand, TTS suppressed expression of P-glucoprotein in MDR HCC cells, and thereby increased accumulation of doxorubicin from 126 ng/10(5)cells to 752 ng/10(5)cells (p<0.01). TTS also repressed expression of many other MDR genes, such as MRP1, MRP2, MRP3, MRP5, MVP and GST-π. In vivo, TTS dose-dependently reduced R-HepG2 cells xenografts tumour formation by inhibiting tumour cells proliferation in mice. Consistence with in vitro finding, TTS induced R-HepG2 sensitization to doxorubicin and therefore reduced tumour formation in vivo.

Related: Doxorubicin

Silos-Santiago I, Hannig G, Eutamene H, et al.
Gastrointestinal pain: unraveling a novel endogenous pathway through uroguanylin/guanylate cyclase-C/cGMP activation.
Pain. 2013; 154(9):1820-30 [PubMed] Related Publications
The natural hormone uroguanylin regulates intestinal fluid homeostasis and bowel function through activation of guanylate cyclase-C (GC-C), resulting in increased intracellular cyclic guanosine-3',5'-monophosphate (cGMP). We report the effects of uroguanylin-mediated activation of the GC-C/cGMP pathway in vitro on extracellular cGMP transport and in vivo in rat models of inflammation- and stress-induced visceral hypersensitivity. In vitro exposure of intestinal Caco-2 cells to uroguanylin stimulated bidirectional, active extracellular transport of cGMP into luminal and basolateral spaces. cGMP transport was significantly and concentration dependently decreased by probenecid, an inhibitor of cGMP efflux pumps. In ex vivo Ussing chamber assays, uroguanylin stimulated cGMP secretion from the basolateral side of rat colonic epithelium into the submucosal space. In a rat model of trinitrobenzene sulfonic acid (TNBS)-induced visceral hypersensitivity, orally administered uroguanylin increased colonic thresholds required to elicit abdominal contractions in response to colorectal distension (CRD). Oral administration of cGMP mimicked the antihyperalgesic effects of uroguanylin, significantly decreasing TNBS- and restraint stress-induced visceromotor response to graded CRD in rats. The antihyperalgesic effects of cGMP were not associated with increased colonic spasmolytic activity, but were linked to significantly decreased firing rates of TNBS-sensitized colonic afferents in rats in response to mechanical stimuli. In conclusion, these data suggest that the continuous activation of the GC-C/cGMP pathway along the intestinal tract by the endogenous hormones guanylin and uroguanylin results in significant reduction of gastrointestinal pain. Extracellular cGMP produced on activation of GC-C is the primary mediator in this process via modulation of sensory afferent activity.

Related: Colorectal (Bowel) Cancer Signal Transduction

Horiguchi S, Shiraha H, Nagahara T, et al.
Loss of runt-related transcription factor 3 induces gemcitabine resistance in pancreatic cancer.
Mol Oncol. 2013; 7(4):840-9 [PubMed] Related Publications
BACKGROUND & AIM: Runt-related transcription factor 3 (RUNX3) is a tumor suppressor gene that is expressed in gastric and other cancers including pancreatic cancer. However, the precise function of RUNX3 in pancreatic cancer has not been fully elucidated. In this study, we aimed to determine the effect of decreased RUNX3 expression in pancreatic cancer.
METHODS: This study included 36 patients with primary pancreatic cancer, who had undergone pancreaticoduodenectomy. All patients were treated with 1000 mg/m2 gemcitabine after the surgery. The pancreatic cancer cell lines PANC-1, MIAPaCa-2, BxPC-3, SUIT-2, and KLM-1 were used for immunoblotting analysis of RUNX3 and multidrug resistance protein (MRP) expressions. Ectopic RUNX3 expression was achieved by cDNA transfection of the cells, and small interfering RNA (siRNA) against RUNX3 was used to knock down endogenous RUNX3. Cell growth in the presence of gemcitabine was assessed using the MTT assay.
RESULTS: Patients with RUNX3-positive and RUNX3-negative pancreatic cancer had a median survival of 1006 and 643 days, respectively. Exogenous RUNX3 expression reduced the expression of MRP1, MRP2, and MRP5 in endogenous RUNX3-negative cells, whereas RUNX3 siRNA increased the expressions of these genes in endogenous RUNX3-positive cells. Exogenous RUNX3 expression decreased gemcitabine IC50 in RUNX3-negative cells.
CONCLUSION: Loss of RUNX3 expression contributes to gemcitabine resistance by inducing MRP expression, thereby resulting in poor patient survival.

Related: RUNX3 Cancer of the Pancreas Pancreatic Cancer Gemcitabine

Mohelnikova-Duchonova B, Brynychova V, Oliverius M, et al.
Differences in transcript levels of ABC transporters between pancreatic adenocarcinoma and nonneoplastic tissues.
Pancreas. 2013; 42(4):707-16 [PubMed] Related Publications
OBJECTIVES: The aim of this study was to evaluate transcript levels of all 49 human ATP-binding cassette transporters (ABCs) in one of the most drug-resistant cancers, namely, the pancreatic ductal adenocarcinoma (PDAC). Association of ABCs levels with clinical-pathologic characteristics and KRAS mutation status was followed as well.
METHODS: Tumors and adjacent nonneoplastic tissues were obtained from 32 histologically verified PDAC patients. The transcript profile of ABCs was assessed using quantitative real-time polymerase chain reaction with a relative standard curve. KRAS mutations in exon 2 were assessed by high-resolution melting analysis and sequencing.
RESULTS: Most ABCs were deregulated in PDAC and 10 ABCs were associated with clinical-pathologic characteristics. KRAS mutations did not change the global expression profile of ABCs.
CONCLUSIONS: The expression of ABC transporters was significantly deregulated in PDAC tumors when compared to nonmalignant tissues. The observed up-regulation of ABCB4, ABCB11, ABCC1, ABCC3, ABCC5, ABCC10, and ABCG2 in tumors may contribute to the generally poor treatment response of PDAC. The up-regulation of ABCA1, ABCA7, and ABCG1 implicates a serious impairment of cellular cholesterol homeostasis in PDAC. On the other hand, the observed down-regulation of ABCA3, ABCC6, ABCC7, and ABCC8 suggests a possible role of stem cells in the development and progression of PDAC.

Related: Cancer of the Pancreas Pancreatic Cancer KRAS gene

Litviakov NV, Cherdyntseva NV, Tsyganov MM, et al.
Changing the expression vector of multidrug resistance genes is related to neoadjuvant chemotherapy response.
Cancer Chemother Pharmacol. 2013; 71(1):153-63 [PubMed] Related Publications
PURPOSE: We aimed to examine the association between alterations in multidrug resistance (MDR) gene expression, measured before and after neoadjuvant chemotherapy (NAC), and short-term response in a cohort of stage IIA-IIIC breast cancer patients (n = 84).
METHODS: All patients were treated with two to four preoperative cycles of FAC (5-fluorouracil-adriamycin-cyclophosphamide), CAX (cyclophosphamide-adriamycin-xeloda) or taxane regimes. The expression levels of key MDR genes (ABCB1, ABCC1, ABCC2, ABCC3, ABCC5, ABCG1, ABCG2, GSTP1, and MVP) were evaluated in both tumor tissues obtained pre-therapy and in specimens removed by final surgery, using TaqMan-based quantitative reverse transcriptase PCR.
RESULTS: No significant difference in the average level of MDR gene expression in paired breast tumors before and after NAC was found when analyzed in both responsive and non-responsive patients. There was no correlation between the expression levels of MDR genes in pre-NAC tumors and immediate NAC response. In the group with tumor responses, we found a statistically significant downregulation of expression of ABCB1, ABCC1, ABCC2, ABCC5, ABCG1, ABCG2, GSTP1, and MVP genes following NAC in FAC and CAX-treated patients (67-93% of cases). In contrast, we found that expression of these genes was upregulated after NAC, mostly in non-responsive patients (55-96% of cases). Responsiveness to taxotere was related to reduced levels of ABCB1, ABCC2, ABCG1, ABCG2, and MVP mRNA in tumor samples collected after chemotherapy.
CONCLUSION: Our results suggest that reductions in MDR gene expression in post-NAC samples in comparison with pre-NAC are associated with tumor response to FAC and CAX as well as taxotere-based NAC, while patients displaying MDR gene upregulation had resistance to therapy.

Related: Breast Cancer

Røe OD, Szulkin A, Anderssen E, et al.
Molecular resistance fingerprint of pemetrexed and platinum in a long-term survivor of mesothelioma.
PLoS One. 2012; 7(8):e40521 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Pemetrexed, a multi-folate inhibitor combined with a platinum compound is the first-line treatment of malignant mesothelioma, but median survival is still one year. Intrinsic and acquired resistance to pemetrexed is common, but its biological basis is obscure. Here we report for the first time a genome-wide profile of acquired resistance in the tumour from an exceptional case with advanced pleural mesothelioma and almost six years survival after 39 cycles of second-line pemetrexed/carboplatin treatment.
METHODOLOGY AND PRINCIPAL FINDINGS: Genome-wide analysis with Illumina BeadChip Kit of 25,000 genes was performed on mRNA from pre-treatment and post-resistance biopsies from this individual as well on case and control samples from our previously published study (in total 17 samples). Cell specific expression of proteins encoded by selected genes were analysed by immunohistochemistry. Serial serum levels of CA125, CYFRA21-1 and SMRP levels were examined. TS protein, the main target of pemetrexed was overexpressed. Proteins and genes related to DNA damage response, elongation and telomere extension and repair related directly and indirectly to platinum resistance were overexpressed, as the CHK1 protein and the genes CHEK2, LIG3, POLD1, POLA2, FANCD2, PRPF19, RECQ5 respectively, the last two not previously described in mesothelioma. We observed a down-regulation of leukocyte transendothelial migration and cell adhesion molecules pathways. Silencing of NT5C in two mesothelioma cell lines did not sensitize the cells to Pemetrexed. Proposed resistance markers are TS, KRT7/ CK7, TYMP/ thymidine phosphorylase and down-regulated SPARCL1 and CDKN1B. Moreover, comparison of the primary expression of the sensitive versus a primary resistant case showed multi-fold overexpressed DNA repair, cell cycle, cytokinesis, and spindle formation in the latter. Serum CA125 and SMRP reflected the clinical and radiological course and tumour burden.
CONCLUSIONS: Genome-wide microarray of mesothelioma pre- and post-resistance biopsies indicated a novel resistance signature to pemetrexed/carboplatin that deserve validation in a larger cohort.

Related: Mesothelioma Pemetrexed

Eggen T, Sager G, Berg T, et al.
Increased gene expression of the ABCC5 transporter without distinct changes in the expression of PDE5 in human cervical cancer cells during growth.
Anticancer Res. 2012; 32(8):3055-61 [PubMed] Related Publications
Carcinoma of the uterine cervix represents the second most frequent female malignancy worldwide, but few biochemical tumour markers have been implemented into clinical practice. Elevated extracellular guanosine 3', 5'-cyclic monophosphate (cGMP) levels have been reported to be a sensitive, early and reliable marker for screening relapse in carcinoma of the uterine cervix. The mechanism behind this observation remains unknown. The possibility exists that the cancer cells develop resistance to the antiproliferative effect of high intracellular cGMP levels. The enhanced cGMP expression may originate from either an increase in cellular export capacity by increased expression of member 5 in subfamily C of ATP-Binding-Cassette transporters (ABCC5), or increased substrate (cGMP) levels for this pump. The latter situation occurs with increased expression of inducible nitric oxide synthase (iNOS) and/or soluble guanylyl cyclase (sGC) and/or reduced expression of member 5 of the cyclic nucleotide phosphodiesterases (PDE5). Four transformed human cell lines derived from carcinomas of the uterine cervix (C-4 I, C-33 A, SiHa and ME-180 cells) and one non-transformed human cell line (WI-38) were included in the study in order to unveil which biokinetic components are involved. The expressions of iNOS, sGC, PDE5 and ABCC5 in the initial and final phase of the exponential growth curve were compared. Assuming that the WI-38 control cells mimic the situation in a normal tissue, iNOS remains un-expressed during proliferation, and the expression of sGC is low but shows a clear increase during exponential growth. PDE5 is highly expressed and increases (≈130%) during growth whereas ABCC5 exhibited low to moderate expression, with a moderate increase (≈40%) during growth. The malignant cells exhibited moderate ABCC5 expression with a distinct increase during exponential growth, whereas PDE5 expression remained virtually unchanged. Dysregulation of the cGMP biokinetics in growing malignant cells may account for the elevation of extracellular cGMP observed in patients with carcinoma of the uterine cervix.

Related: Cervical Cancer

Zhang X, Li W, Li H, et al.
Genomic methylation profiling combined with gene expression microarray reveals the aberrant methylation mechanism involved in nasopharyngeal carcinoma taxol resistance.
Anticancer Drugs. 2012; 23(8):856-64 [PubMed] Related Publications
Taxol is a first-line chemoagent used for treatment of nasopharyngeal carcinoma (NPC). A major obstacle to achieving successful treatment is the development of cellular taxol drug resistance. Aberrant DNA methylation has been recognized to be associated with the transcriptional inactivation of genes related to cancer drug resistance development. To identify the mechanism of DNA methylation involved in NPC taxol resistance, we applied a genome-wide DNA methylation microarray assay to reveal methylation alteration in taxol-resistant NPC cell lines (CNE-1/taxol, 5-8F/taxol, HNE-2/taxol) established previously in our laboratory. Combining with gene expression microarray, we identified drug resistance-associated genes in taxol-resistant cell lines. We also investigated the coeffect of taxol and the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) to confirm the involvement of DNA methylation. The methylation profiling revealed differential patterns between the drug-sensitive and -resistant cell lines. As a result, taxol-resistant cell lines were detected to be globally hypermethylated. Forty-eight differentially methylated genes (30 hypermethylated and 18 hypomethylated) were further identified commonly in the three taxol-resistant cell lines. Six of them (DLC1, CHFR, ABCC5, PEG10, ERBB2, and GSTP1) were independently confirmed to contribute to taxol resistance by both methylation-specific PCR and quantitative real-time PCR. Finally, we conclude that DNA methylation is closely correlated with taxol drug resistance in NPC cells. Combined analysis of DNA methylation and gene expression may enable the discovery of new therapeutic targets and prognostic biomarkers of cancers. Furthermore, DNA methylation inhibitors can reverse chemoresistance and prevent the development of acquired drug resistance.

Related: Azacitidine Nasopharyngeal Cancer Paclitaxel

Zhu Y, Yu F, Jiao Y, et al.
Reduced miR-128 in breast tumor-initiating cells induces chemotherapeutic resistance via Bmi-1 and ABCC5.
Clin Cancer Res. 2011; 17(22):7105-15 [PubMed] Related Publications
PURPOSE: Tumor-initiating cells are resistant to chemotherapy, but how microRNAs play a role in regulating drug resistance of breast tumor-initiating cells (BT-IC) needs to be clarified.
EXPERIMENTAL DESIGN: Lentivirus-mediated miR-128 transduction was done in BT-ICs, enriched by mammosphere cultures or CD44(+)CD24(-) fluorescence-activated cell sorting. Apoptosis and DNA damage were determined upon treatment with doxorubicin. Expression of miR-128 in breast cancer tissues was examined by in situ hybridization and correlated with breast tumor response to neoadjuvant chemotherapy and patient survival.
RESULTS: MiR-128 was significantly reduced in chemoresistant BT-ICs enriched from breast cancer cell lines and primary breast tumors (P < 0.01), accompanied by an overexpression of Bmi-1 and ABCC5, which were identified as targets of miR-128. Ectopic expression of miR-128 reduced the protein levels of Bmi-1 and ABCC5 in BT-ICs, along with decreased cell viability (P < 0.001) and increased apoptosis (P < 0.001) and DNA damage (P < 0.001) in the presence of doxorubicin. Reduced miR-128 expression in breast tumor tissues was associated with chemotherapeutic resistance (P < 0.001) and poor survival of breast cancer patients (P < 0.05; n = 57).
CONCLUSIONS: Reduction in miR-128 leading to Bmi-1 and ABCC5 overexpression is a stem cell-like feature of BT-ICs, which contributes to chemotherapeutic resistance in breast cancers. Ectopic expression of miR-128 sensitizes BT-ICs to the proapoptotic and DNA-damaging effects of doxorubicin, indicating therapeutic potential.

Related: Breast Cancer Doxorubicin

Borel F, Han R, Visser A, et al.
Adenosine triphosphate-binding cassette transporter genes up-regulation in untreated hepatocellular carcinoma is mediated by cellular microRNAs.
Hepatology. 2012; 55(3):821-32 [PubMed] Related Publications
UNLABELLED: Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are drug efflux pumps responsible for the multidrug resistance phenotype causing hepatocellular carcinoma (HCC) treatment failure. Here we studied the expression of 15 ABC transporters relevant for multidrug resistance in 19 paired HCC patient samples (16 untreated, 3 treated by chemotherapeutics). Twelve ABC transporters showed up-regulation in HCC compared with adjacent healthy liver. These include ABCA2, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC4, ABCC5, ABCC10, ABCC11, ABCC12, and ABCE1. The expression profile and function of some of these transporters have not been associated with HCC thus far. Because cellular microRNAs (miRNAs) are involved in posttranscriptional gene silencing, we hypothesized that regulation of ABC expression in HCC might be mediated by miRNAs. To study this, miRNAs were profiled and dysregulation of 90 miRNAs was shown in HCC compared with healthy liver, including up-regulation of 11 and down-regulation of 79. miRNA target sites in ABC genes were bioinformatically predicted and experimentally verified in vitro using luciferase reporter assays. In total, 13 cellular miRNAs were confirmed that target ABCA1, ABCC1, ABCC5, ABCC10, and ABCE1 genes and mediate changes in gene expression. Correlation analysis between ABC and miRNA expression in individual patients revealed an inverse relationship, providing an indication for miRNA regulation of ABC genes in HCC.
CONCLUSION: Up-regulation of ABC transporters in HCC occurs prior to chemotherapeutic treatment and is associated with miRNA down-regulation. Up-regulation of five ABC genes appears to be mediated by 13 cellular miRNAs in HCC patient samples. miRNA-based gene therapy may be a novel and promising way to affect the ABC profile and overcome clinical multidrug resistance.

Related: Liver Cancer

Di Martino MT, Arbitrio M, Leone E, et al.
Single nucleotide polymorphisms of ABCC5 and ABCG1 transporter genes correlate to irinotecan-associated gastrointestinal toxicity in colorectal cancer patients: a DMET microarray profiling study.
Cancer Biol Ther. 2011; 12(9):780-7 [PubMed] Related Publications
Recent findings have disclosed the role of UDP-glucuronosyltransferase (UGT) 1A1*28 on the haematological toxicity induced by irinotecan (CPT-11), a drug commonly used in the treatment of metastatic colorectal cancer (mCRC). We investigated the pharmacogenomic profile of irinotecan-induced gastrointestinal (GI) toxicity by the novel drug-metabolizing enzyme and transporter (DMET) microarray genotyping platform. Twenty-six mCRC patients who had undergone to irinotecan-based chemotherapy were enrolled in a case (patients experiencing ≥ grade 3 gastrointestinal, (GI) toxicity) - control (matched patients without GI toxicity) study. A statistically significant difference of SNP genotype distribution was found in the case versus control group. The homozygous genotype C/C in the (rs562) ABCC5 gene occurred in 6/9 patients with GI toxicity versus 1/17 patients without GI toxicity (P=0.0022). The homozygous genotype G/G in the (rs425215) ABCG1 was found in 7/9 patients with GI toxicity versus 4/17 patients without GI toxicity (P=0.0135). The heterozygous genotype G/A in the 388G>A (rs2306283) OATP1B1/SLCO1B1 was found in 3/9 patients with grade ≥ 3 GI toxicity vs. 14/17 patients without GI toxicity (P=0.0277). DNA extracted from peripheral blood cells was genotyped by DMET Plus chip on Affymetrix array system. Genotype association was calculated by Fisher's exact test (two tailed) and relevant SNPs were further analyzed by direct sequencing. We have identified 3 SNPs mapping in ABCG1, ABCC5 and OATP1B1/SLCO1B1 transporter genes associated with GI toxicity induced by irinotecan in mCRC patients expanding the available knowledge of irinogenomics. The DMET microarray platform is an emerging technology for easy identification of new genetic variants for personalized medicine.

Related: Colorectal (Bowel) Cancer Irinotecan

Brechbuhl HM, Kachadourian R, Min E, et al.
Chrysin enhances doxorubicin-induced cytotoxicity in human lung epithelial cancer cell lines: the role of glutathione.
Toxicol Appl Pharmacol. 2012; 258(1):1-9 [PubMed] Free Access to Full Article Related Publications
We hypothesized that flavonoid-induced glutathione (GSH) efflux through multi-drug resistance proteins (MRPs) and subsequent intracellular GSH depletion is a viable mechanism to sensitize cancer cells to chemotherapies. This concept was demonstrated using chrysin (5-25 μM) induced GSH efflux in human non-small cell lung cancer lines exposed to the chemotherapeutic agent, doxorubicin (DOX). Treatment with chrysin resulted in significant and sustained intracellular GSH depletion and the GSH enzyme network in the four cancer cell types was predictive of the severity of chrysin induced intracellular GSH depletion. Gene expression data indicated a positive correlation between basal MRP1, MRP3 and MRP5 expression and total GSH efflux before and after chrysin exposure. Co-treating the cells for 72 h with chrysin (5-30 μM) and DOX (0.025-3.0 μM) significantly enhanced the sensitivity of the cells to DOX as compared to 72-hour DOX alone treatment in all four cell lines. The maximum decrease in the IC(50) values of cells treated with DOX alone compared to co-treatment with chrysin and DOX was 43% in A549 cells, 47% in H157 and H1975 cells and 78% in H460 cells. Chrysin worked synergistically with DOX to induce cancer cell death. This approach could allow for use of lower concentrations and/or sensitize cancer cells to drugs that are typically resistant to therapy.

Related: Doxorubicin Lung Cancer

Nelson HH, Almquist LM, LaRocca JL, et al.
The relationship between tumor MSLN methylation and serum mesothelin (SMRP) in mesothelioma.
Epigenetics. 2011; 6(8):1029-34 [PubMed] Free Access to Full Article Related Publications
Malignant pleural mesothelioma (MPM) remains a cancer of poor prognosis. It is hoped that implementation of effective screening biomarkers will lead to earlier diagnoses and improved outcomes. Serum-measured soluble mesothelin-related peptide (SMRP) has been demonstrated to have excellent specificity for MPM, but poor sensitivity precludes its use as a screening biomarker. Using a case series of MPM patients from the International Mesothelioma Program at the Brigham and Women's hospital, we sought to determine whether epigenetic change at the MSLN gene in patient tumors is responsible for the poor sensitivity of SMRP. We identified three potential target regions for CpG methylation silencing in the MSLN promoter, one of which was amenable to bisulfite pyrosequencing and located 214 bp upstream of the transcription start site. MSLN promoter methylation was significantly higher in normal pleura than tumor tissue (P < 6.0x10-9). Next, we compared cases according to serum SMRP status and observed that MSLN methylation was significantly higher among tumors from patients testing negative for SMRP (< 1.5nM) versus those that were SMRP positive (P < 0.03). These results demonstrate that MSLN is normally methylated in the pleura, and that methylation is lost in most tumors. However, in a subset of tumors methylation is retained, and this mechanism explains the poor sensitivity of the SMRP assay. These results may lead to additional biomarker targets that will resolve the poor sensitivity of the SMRP assay and allow implementation of screening among exposed populations.

Related: Mesothelioma

Cristaudo A, Foddis R, Bonotti A, et al.
Two novel polymorphisms in 5' flanking region of the mesothelin gene are associated with soluble mesothelin-related peptide (SMRP) levels.
Int J Biol Markers. 2011 Apr-Jun; 26(2):117-23 [PubMed] Related Publications
BACKGROUND AND AIMS: Increased concentrations of soluble mesothelin-related peptides (SMRP) have been found in sera of patients with malignant pleural mesothelioma (MPM) even if a relatively high rate of false positives has hampered their clinical use as a tumor marker. Individual SMRP levels could be affected by polymorphic elements. The aim of this study was to investigate the association between single nucleotide polymorphisms within the promoter-5'UTR regions and SMRP levels in healthy asbestos-exposed individuals and patients suffering from MPM.?
METHODS: The promoter-5'UTR regions of the mesothelin gene were genotyped in 59 healthy asbestos-exposed subjects and 27 MPM patients. SMRP levels were measured using a commercially available ELISA kit.?
RESULTS: Two novel polymorphisms, an A>C variant (called New1) and a C>T variant (called New2), were identified. In healthy subjects, high SMRP levels were associated with the C-variant of New1, with an average 1.62-fold increase compared with AA homozygotes (p<0.0001). Most of the C-allele carriers had SMRP levels above the threshold of 1.00 nM. We set two different SMRP cutoffs on the basis of the combined New1+New2 genotypes.?
CONCLUSIONS: New1-New2 genotypes could be employed as markers for setting individualized and appropriate thresholds of "normality" when SMRP is used in surveillance programs of asbestos-exposed people.

Related: Mesothelioma Polymorphisms

Alhopuro P, Sammalkorpi H, Niittymäki I, et al.
Candidate driver genes in microsatellite-unstable colorectal cancer.
Int J Cancer. 2012; 130(7):1558-66 [PubMed] Related Publications
Defects in the mismatch repair system lead to microsatellite instability (MSI), a feature observed in ∼ 15% of all colorectal cancers (CRCs). Microsatellite mutations that drive tumourigenesis, typically inactivation of tumour suppressors, are selected for and are frequently detected in MSI cancers. Here, we evaluated somatic mutations in microsatellite repeats of 790 genes chosen based on reduced expression in MSI CRC and existence of a coding mononucleotide repeat of 6-10 bp in length. All the repeats were initially sequenced in 30 primary MSI CRC samples and whenever frameshift mutations were identified in >20%, additional 70 samples were sequenced. To distinguish driver mutations from passengers, we similarly analyzed the occurrence of frameshift mutations in 121 intronic control repeats and utilized a statistical regression model to determine cut-off mutation frequencies for repeats of all types (A/T and C/G, 6-10 bp). Along with several know target genes, including TGFBR2, ACVR2, and MSH3, six novel candidate driver genes emerged that harbored significantly more mutations than identical control repeats. The mutation frequencies in 100 MSI CRC samples were 51% in G8 of GLYR1, 47% in T9 of ABCC5, 43% in G8 of WDTC1, 33% in A8 of ROCK1, 30% in T8 of OR51E2, and 28% in A8 of TCEB3. Immunohistochemical staining of GLYR1 revealed defective protein expression in tumors carrying biallelic mutations, supporting a loss of function hypothesis. This is a large scale, unbiased effort to identify genes that when mutated are likely to contribute to MSI CRC development.

Related: Colorectal (Bowel) Cancer

Marquez B, Van Bambeke F
ABC multidrug transporters: target for modulation of drug pharmacokinetics and drug-drug interactions.
Curr Drug Targets. 2011; 12(5):600-20 [PubMed] Related Publications
Nine proteins of the ABC superfamily (P-glycoprotein, 7 MRPs and BCRP) are involved in multidrug transport. Being localised at the surface of endothelial or epithelial cells, they expel drugs back to the external medium (if located at the apical side [P-glycoprotein, BCRP, MRP2, MRP4 in the kidney]) or to the blood (if located at the basolateral side [MRP1, MRP3, MRP4, MRP5]), modulating thereby their absorption, distribution, and elimination. In the CNS, most transporters are oriented to expel drugs to the blood. Transporters also cooperate with Phase I/Phase II metabolism enzymes by eliminating drug metabolites. Their major features are (i) their capacity to recognize drugs belonging to unrelated pharmacological classes, and (ii) their redundancy, a single molecule being possibly substrate for different transporters. This ensures an efficient protection of the body against invasion by xenobiotics. Competition for transport is now characterized as a mechanism of interaction between co-administered drugs, one molecule limiting the transport of the other, potentially affecting bioavailability, distribution, and/or elimination. Again, this mechanism reinforces drug interactions mediated by cytochrome P450 inhibition, as many substrates of P-glycoprotein and CYP3A4 are common. Induction of the expression of genes coding for MDR transporters is another mechanism of drug interaction, which could affect all drug substrates of the up-regulated transporter. Overexpression of MDR transporters confers resistance to anticancer agents and other therapies. All together, these data justify why studying drug active transport should be part of the evaluation of new drugs, as recently recommended by the FDA.

Related: Cancer Prevention and Risk Reduction

Nambaru PK, Hübner T, Köck K, et al.
Drug efflux transporter multidrug resistance-associated protein 5 affects sensitivity of pancreatic cancer cell lines to the nucleoside anticancer drug 5-fluorouracil.
Drug Metab Dispos. 2011; 39(1):132-9 [PubMed] Related Publications
Pancreatic adenocarcinoma is one of the malignancies that is highly resistant to therapy and among the leading causes of cancer-related death. Several factors may influence pancreatic cancer resistance, and expression of ATP-binding cassette transport proteins is one of the major mechanisms of drug resistance. Members of this family's C-branch, also referred to as multidrug resistance-associated proteins (MRPs), might be of particular interest because they are able to efflux nucleoside analogs used in the treatment of pancreatic cancer. Expression of MRP1, MRP3, MRP4, and MRP5 in human pancreas and pancreatic carcinoma has been reported. However, contributions of MRPs to chemoresistance of pancreatic cancer are not fully understood. MRP5 mRNA expression in pancreatic adenocarcinoma cell lines correlated significantly with cellular sensitivity to 5-fluorouracil (5-FU) (r = 0.738, p < 0.05). Long-term treatment with 5-FU increased expression of MRP5 by 2.4-fold and was associated with significant drug resistance [IC(50) values for control and 5-fluorouracil (5-FU)-resistant Patu-T cell lines were 11.3 ± 5.3 and 33.2 ± 6.9 μM, respectively (p < 0.05)]. Consequently, overexpression of MRP5 in Colo-357 cells resulted in significantly reduced accumulation of 5-FU related radioactivity and 5-FU cytotoxicity. Knockdown of MRP5 significantly increased cellular cytotoxicity of 5-FU to Patu-02 cells and enhanced accumulation of radioactivity related to 5-FU and its metabolites. Our results suggest that MRP5 is expressed and functionally active and contributes to variable sensitivities of pancreatic adenocarcinoma cell lines to 5-FU. Further investigations using models that resemble human pancreas tumors are necessary to prove a causative relation between expression and activity of MRP5 and tumor resistance to 5-FU.

Related: Fluorouracil Cancer of the Pancreas Pancreatic Cancer

Tanaka M, Okazaki T, Suzuki H, et al.
Association of multi-drug resistance gene polymorphisms with pancreatic cancer outcome.
Cancer. 2011; 117(4):744-51 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The purpose of this study was to identify single nucleotide polymorphisms (SNPs) of multidrug resistance genes that are associated with clinical outcome in patients with potentially resectable pancreatic adenocarcinoma who were treated with preoperative gemcitabine-based chemoradiotherapy at M. D. Anderson Cancer Center.
METHODS: We selected 8 SNPs of 7 drug resistance genes, including MDR1 (ABCB1), MRP1-5 (ABCC1-5), and BCRP (ABCG2), reported to be important in mediating drug resistance. Genotype was determined by the Taqman method. The associations of genotype with tumor response to therapy and overall survival (OS) were evaluated using log-rank test, Cox regression, and logistic regression models.
RESULTS: MRP5 A-2G AA genotype showed significant association with OS (log-rank P = .010). The hazard ratio (95% confidence interval) was 1.65 (1.11-2.45) after adjusting for clinical predictors. The MRP2 G40A GG genotype had a weak association with reduced OS (log-rank P = .097). A combined effect of the two genotypes on OS was observed. Patients with none of the adverse genotypes had a median survival time (MST) of 34.0 months, and those with 1-2 deleterious alleles had a significantly lower MST of 20.7 months (log-rank P = .006). MRP2 G40A GG genotype was also significantly associated with poor histological response to chemoradiotherapy (P = .028).
CONCLUSIONS: These observations suggest a potential role of polymorphic variants of drug resistance genes in predicting therapeutic efficacy and survival of patients with potentially resectable pancreatic cancer.

Related: Cancer of the Pancreas Pancreatic Cancer

Hagmann W, Jesnowski R, Löhr JM
Interdependence of gemcitabine treatment, transporter expression, and resistance in human pancreatic carcinoma cells.
Neoplasia. 2010; 12(9):740-7 [PubMed] Free Access to Full Article Related Publications
Gemcitabine is widely used as first-line chemotherapeutic drug in the treatment of pancreatic cancer. Our previous experimental chemotherapy studies have shown that treatment of human pancreatic carcinoma cells with 5-fluorouracil (5-FU) alters the cellular transporter expression profile and that modulation of the expression of multidrug resistance protein 5 (MRP5; ABCC5) influences the chemoresistance of these tumor cells. Here, we studied the influence of acute and chronic gemcitabine treatment on the expression of relevant uptake and export transporters in pancreatic carcinoma cells by reverse transcription-polymerase chain reaction (RT-PCR), quantitative RT-PCR, and immunoblot analyses. The specific role of MRP5 in cellular gemcitabine sensitivity was studied by cytotoxicity assays using MRP5-overexpressing and MRP5-silenced cells. Exposure to gemcitabine (12 nM for 3 days) did not alter the messenger RNA (mRNA) expression of MRP1, MRP3, MRP5, and equilibrative nucleoside transporter 1 (ENT1), whereas high dosages of the drug (20 microM for 1 hour) elicited up-regulation of these transporters in most cell lines studied. In cells with acquired gemcitabine resistance (up to 160 nM gemcitabine), the mRNA or protein expression of the gemcitabine transporters MRP5 and ENT1 was upregulated in several cell lines. Combined treatment with 5-FU and gemcitabine caused a 5- to 40-fold increase in MRP5 and ENT1 expressions. Cytotoxicity assays using either MRP5-overexpressing (HEK and PANC-1) or MRP5-silenced (PANC1/shMRP5) cells indicated that MRP5 contributes to gemcitabine resistance. Thus, our novel data not only on drug-induced alterations of transporter expression relevant for gemcitabine uptake and export but also on the link between gemcitabine sensitivity and MRP5 expression may lead to improved strategies of future chemotherapy regimens using gemcitabine in pancreatic carcinoma patients.

Related: Cancer of the Pancreas Pancreatic Cancer Gemcitabine

Trtkova K, Paskova L, Matijescukova N, et al.
Binding of AR to SMRT/N-CoR complex and its co-operation with PSA promoter in prostate cancer cells treated with natural histone deacetylase inhibitor NaB.
Neoplasma. 2010; 57(5):406-14 [PubMed] Related Publications
Signaling through the androgen receptor (AR) plays a critical role in prostate cancer progression. The AR is a classical nuclear receptor (NR) providing a link between signaling molecule and transcription response. Histone deacetylase inhibitors- (HDACI) have antiproliferative and proapoptotic effects on prostate cancer cells and their implication in silence AR signaling may have potential therapeutic use. We aimed to study the inhibitory effects of the corepressor SMRT (Silencing Mediator for Retinoid and Thyroid -hormone receptors) which forms a complex together with nuclear receptor corepressor (N-CoR) and with histone deacetylase 3 (HDAC3) on AR activity.The androgen-sensitive prostate cancer cell line LNCaP and androgen-insensitive prostate cancer cell line C4-2 both AR-positive, and androgen-insensitive DU145 and PC3 prostate cancer cell lines were treated with two HDACIs, sodium butyrate (NaB) and/or trichostatin A (TSA). We amplified immunoprecipitated DNA by conventional PCR and in the -following step we used the chromatin immunoprecipitation (ChIP) analysis coupled with quantitative PCR for monitoring NaB induced formation of AR-SMRT/N-CoR complex binding on the PSA promoter. The co-immunoprecipitation assay revealed increase in AR-SMRT formation in NaB treated cells. Simultaneously, the Western blot analysis showed a significant decrease in AR protein expression. In conclusion, the inhibitory effect of NaB on AR gene expression seems to be specific and unique for prostate cancer AR-positive cell lines and corresponds with its ability to stimulate AR-SMRT complex formation. We suggest that AR and SMRT/N-CoR corepressors may form a stable complex in vitro and NaB may facilitate the interaction between AR nuclear steroid receptor and SMRT corepressor prote.

Related: Prostate Cancer AR: androgen receptor

Alexiou GA, Goussia A, Kyritsis AP, et al.
Influence of glioma's multidrug resistance phenotype on (99m)Tc-tetrofosmin uptake.
Mol Imaging Biol. 2011; 13(2):348-51 [PubMed] Related Publications
PURPOSE: Multidrug resistance (MDR) remains a major obstacle to successful chemotherapeutic treatment of cancer. Several chemotherapeutic and radiopharmaceutical agents are substrates of the pumps encoded by the MDR genes, and therefore, their accumulation is prevented. We evaluated in vivo whether [(99m)Tc]tetrofosmin ((99m)Tc-TF) uptake is influenced by the MDR profile of gliomas.
PROCEDURES: Eighteen patients with histologically confirmed glioma were included in the study. Brain single-photon emission computed tomography by (99m)Tc-TF was performed within a week prior to surgical excision, and the expression of MRP5 was assessed by immunohistochemistry. Radiotracer accumulation was assessed by a semiquantitative method, calculating the lesion-to-normal uptake ratio.
RESULTS: Using Spearman's ρ analysis, we found no correlation between tracer uptake expressed as lesion-to-normal and MRP5 expression. There was a significant correlation between glioma aggressiveness as assessed by Ki-67/MIB-1 and MRP5 expression.
CONCLUSION: The present data suggest that (99m)Tc-TF uptake is not influenced by glioma's MDR phenotype. Thus, (99m)Tc-TF constitutes a suitable radiotracer for imaging gliomas.

Hickinson DM, Marshall GB, Beran GJ, et al.
Identification of biomarkers in human head and neck tumor cell lines that predict for in vitro sensitivity to gefitinib.
Clin Transl Sci. 2009; 2(3):183-92 [PubMed] Related Publications
Potential biomarkers were identified for in vitro sensitivity to the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib in head and neck cancer. Gefitinib sensitivity was determined in cell lines, followed by transcript profiling coupled with a novel pathway analysis approach. Eleven cell lines were highly sensitive to gefitinib (inhibitor concentration required to give 50% growth inhibition [GI(50)] < 1 microM), three had intermediate sensitivity (GI(50) 1-7 microM), and six were resistant (GI(50) > 7 microM); an exploratory principal component analysis revealed a separation between the genomic profiles of sensitive and resistant cell lines. Subsequently, a hypothesis-driven analysis of Affymetrix data (Affymetrix, Inc., Santa Clara, CA, USA) revealed higher mRNA levels for E-cadherin (CDH1); transforming growth factor, alpha (TGF-alpha); amphiregulin (AREG); FLJ22662; EGFR; p21-activated kinase 6 (PAK6); glutathione S-transferase Pi (GSTP1); and ATP-binding cassette, subfamily C, member 5 (ABCC5) in sensitive versus resistant cell lines. A hypothesis-free analysis identified 46 gene transcripts that were strongly differentiated, seven of which had a known association with EGFR and head and neck cancer (human EGF receptor 3 [HER3], TGF-alpha, CDH1, EGFR, keratin 16 [KRT16], fibroblast growth factor 2 [FGF2], and cortactin [CTTN]). Polymerase chain reaction (PCR) and enzyme-linked immunoabsorbant assay analysis confirmed Affymetrix data, and EGFR gene mutation, amplification, and genomic gain correlated strongly with gefitinib sensitivity. We identified biomarkers that predict for in vitro responsiveness to gefitinib, seven of which have known association with EGFR and head and neck cancer. These in vitro predictive biomarkers may have potential utility in the clinic and warrant further investigation.

Related: Head and Neck Cancers Head and Neck Cancers - Molecular Biology Gefitinib (Iressa)

Lal S, Mahajan A, Chen WN, Chowbay B
Pharmacogenetics of target genes across doxorubicin disposition pathway: a review.
Curr Drug Metab. 2010; 11(1):115-28 [PubMed] Related Publications
Increased understanding of the molecular mechanisms of tumor heterogeneity combined with rapid advances in the field of pharmacogenetics and pharmacogenomics have fuelled studies on individualizing anticancer therapy. Doxorubicin (Adriamycin), is an anthracycline glycoside antibiotic originally produced by Streptomyces peucetius var. caesius, and is widely used either as a single agent or in combination with other chemotherapeutic regimens for curative, adjuvant, and palliative treatment in cancer patients. The pharmacogenetics of doxorubicin has not been well characterized. The polygenic influence of functional candidate gene variants across doxorubicin biochemical pathway is hypothesized to contribute to its heterogeneity in disposition, influencing the efficacy of treatment and occurrence of adverse effects like cardiomyopathy in patients undergoing doxorubicin based adjuvant and neo-adjuvant chemotherapy. The pharmacogenetics of Asian population differs from that of other ethnic groups, particularly from Caucasian and African populations, and indicates an important role of ethnicity in determining predictive end points during chemotherapy and in individualizing treatment. This review comprehensively examines the pharmacogenetics of the regulatory nuclear receptor Pregnane-X Receptor (PXR), influx (SLC22A16) and efflux drug transporters (ABCB1, ABCG2, ABCC5, ABCB5 and RLIP76) and drug metabolizing enzymes (CBR1, CBR3) across the biochemical pathway of doxorubicin in Asian breast cancer patients receiving doxorubicin based adjuvant chemotherapy. The influence of functional genetic variants on the inter-individual variability in pharmacokinetics of doxorubicin and its major metabolite are also discussed. The incorporation of non-genetic factors and subsequent validation of these findings in different patient and population groups will be valuable in tailoring doxorubicin dosage regimens to an individual to maximize therapeutic efficacy and minimize adverse reactions, leading to improved clinical outcomes.

Related: Breast Cancer Doxorubicin

Rai AJ, Flores RM, Mathew A, et al.
Soluble mesothelin related peptides (SMRP) and osteopontin as protein biomarkers for malignant mesothelioma: analytical validation of ELISA based assays and characterization at mRNA and protein levels.
Clin Chem Lab Med. 2010; 48(2):271-8 [PubMed] Related Publications
BACKGROUND: There is a need to identify reliable markers for malignant mesothelioma. Soluble mesothelin related peptides (SMRP) and osteopontin (OPN) have gained interest in recent years for this purpose.
METHODS: SMRP (Fujirebio Diagnostics Inc.) and OPN (R&D Inc.) ELISA methods were evaluated for multiple parameters. Concentrations were measured in blood from patients with mesothelioma, normal healthy volunteers, and patients with other (non-mesothelioma) cancers. In silico analysis was performed using the GeoProfiles database. At the protein level, SMRP and OPN were measured in cell culture supernatants, and values were compared in patients pre- and post-extrapleural pneumonectomy.
RESULTS: The SMRP assay demonstrates intra-assay CVs of 2.3% and 3% (at 4.6 nM and 13.7 nM, respectively), and inter-assay CVs of 3.5% and 3.7% at the same concentrations. The limit of detection (LOD) is 0.182 nM. The OPN assay demonstrates intra-assay CVs of 5.8%, 4.1%, and 5.2% (at 1.9, 5.1, and 11.1 ng/mL, respectively), and inter-assay CVs of 8.5%, 8.4%, and 12.1% at the same concentrations. The LOD is 0.032 ng/mL. Both SMRP and OPN in mesothelioma patients were significantly higher than in patients with other (non-mesothelioma) cancer and in healthy volunteers. The two markers do not appear to correlate with each other and exhibit different tissue expression patterns. Protein concentrations of these markers are highest in different sets of cell lines. Finally, SMRP but not OPN concentrations were decreased in five of seven consecutive patients after extrapleural pneumonectomy, compared to their respective pre-operative values.
CONCLUSIONS: These assays provide reliable and reproducible quantitation of SMRP and OPN proteins. Both are increased in mesothelioma patients compared to non-mesothelioma controls. However, the two analytes do not correlate with each other and show distinct expression profiles and protein expression. Concentrations of SMRP but not OPN are decreased in post-surgical samples. Our results further characterize these markers, establish assay performance characteristics, and lay the groundwork for further studies to measure these markers in blood.

Related: Mesothelioma

Thomas NK, Brown TJ
ABC transporters do not contribute to extracellular translocation of hyaluronan in human breast cancer in vitro.
Exp Cell Res. 2010; 316(7):1241-53 [PubMed] Related Publications
Extracellular translocation of the polysaccharide, hyaluronan (HA) has been thought to be mediated via its transmembrane synthetic enzyme, hyaluronan synthase (HAS) but recent studies have indicated that the ATP-Binding-Cassette (ABC) transporter, MRP5 contributes to this process. Liberated and cell-associated HA contributes to breast cancer initiation and progression, and therefore the inhibition of ABC transporters and consequently HA transport could provide therapeutic benefit in the treatment of breast cancer. Quantitation of ABC transporter genes, MRP1-5, BCRP and MDR1 were determined in six breast cancer cell lines selected for their differential HA synthetic rates. Low endogenous expression of transporters was detected but no significant correlation existed between ABC transporter and HAS gene expression or HA production. A dose titration of up to ten times the IC(50) of ten small molecule ABC transporter inhibitors did not significantly inhibit HA export in four breast cancer cell lines. Unlike the changes observed after inhibition of HA synthesis by the characterised inhibitor 4-MU, inhibition of ABC transporters did not alter the cell morphology, HA glycocalyx or the intracellular quantity or localisation of HA. Collectively these data indicate that ABC transporters do not contribute to the extracellular transport of HA in breast cancer, supporting a role for the hyaluronan synthase in translocation.

Related: Breast Cancer ABCG2

Wang XB, Wang SS, Zhang QF, et al.
Inhibition of tetramethylpyrazine on P-gp, MRP2, MRP3 and MRP5 in multidrug resistant human hepatocellular carcinoma cells.
Oncol Rep. 2010; 23(1):211-5 [PubMed] Related Publications
Some membrane transporters in liver, such as P-glycoprotein, multidrug resistance-associated protein 2 (MRP2), MRP3, and MRP5 can lead to a complex multidrug resistance (MDR) to antineoplastic agents. How to inhibit these proteins is still an issue. Tetramethylpyrazine is a bioactive constituent isolated from the root of Ligusticum chuanxiong Hort, a Chinese herb. Recent studies showed that it can enhance the chemosensitivity effects of a drug on human hepatocellular carcinoma cells, acting as a multidrug resistance modulator. In this study, the reversal effect of TMP on MDR was evaluated and its activity mechanism in vitro was explored. The IC50 value shows that TMP reversed the multidrug resistance of BEL-7402/ADM cells 9.23-fold (P<0.01) at the concentration of 600 microM. The mean fluorescence intensity of ADM in BEL-7402/ADM cells with TMP was found to be 163.78+/-39.5% (P<0.01) versus in BEL-7402/ADM cells without TMP by flow cytometry and 126.73+/-28.72% in BEL-7402/ADM cells with TMP versus in BEL-7402/ADM cells without TMP (P<0.01) by high performance liquid chromatography, respectively. It was also found that the mRNA level of multidrug resistant gene MDR1, MRP2, MRP3 and MRP5 and the level of the proteins they encode were decreased after treatment with TMP, indicating that TMP can effectively reverse the MDR in BEL-7402/ADM cells, and its activity mechanism may be correlated with the down-regulation of expression in these transporters.

Related: Doxorubicin Liver Cancer


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