ABCA1

Gene Summary

Gene:ABCA1; ATP binding cassette subfamily A member 1
Aliases: TGD, ABC1, CERP, ABC-1, HDLDT1
Location:9q31.1
Summary:The membrane-associated 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 intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. With cholesterol as its substrate, this protein functions as a cholesteral efflux pump in the cellular lipid removal pathway. Mutations in this gene have been associated with Tangier's disease and familial high-density lipoprotein deficiency. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:ATP-binding cassette sub-family A member 1
Source:NCBIAccessed: 15 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

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

Latest Publications: ABCA1 (cancer-related)

Onishi H, Suyama K, Yamasaki A, et al.
CD24 Modulates Chemosensitivity of MCF-7 Breast Cancer Cells.
Anticancer Res. 2017; 37(2):561-565 [PubMed] Related Publications
The role of cluster of differentiation (CD) 24 in breast cancer remains unclear; previously, we showed that CD24 suppresses malignant phenotypes by inactivating Hedgehog signaling through signal transducer and activator of transcription (STAT) 1 inhibition. In this study, we examined how CD24 affects chemosensitivity in breast cancer cells. The CD44(+)CD24(+) breast cancer cell line MCF-7 was transfected with CD24 with/without STAT1 siRNA, and chemosensitivity to 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum (CDDP) was measured. CD24 inhibition reduced chemosensitivity to 5-FU, while STAT1 inhibition did not affect chemosensitivity to 5-FU in CD24 siRNA-transfected cells. Conversely, CD24 inhibition did not affect chemosensitivity to CDDP, while STAT1 inhibition reduced chemosensitivity to CDDP in CD24 siRNA-transfected cells. STAT1 inhibition, but not CD24 inhibition, reduced expression of the ATP-binding cassette (ABC) transporter genes, ABCB1 and ABCG2. In conclusion, CD24 inhibition may modulate chemosensitivity according to drug type, but ABC transporter expression appears not to contribute to this mechanism. This study contributes to determining the role of CD24 in breast cancer.

Bi DP, Yin CH, Zhang XY, et al.
MiR-183 functions as an oncogene by targeting ABCA1 in colon cancer.
Oncol Rep. 2016; 35(5):2873-9 [PubMed] Related Publications
Colon cancer remains the second most common cause of cancer-related death, indicating that a proportion of cancer cells are not eradicated by current therapies. Investigation of the molecular mechanisms involved in the development and progression of the disease will aid in the further understanding of the pathogenesis and progression and offer new targets for effective therapies. In the present study, we initially confirmed that ABCA1 was aberrantly expressed in colon cancer tissues and colon cancer cells. Its overexpression inhibited the proliferation of colon cancer HCT116 cells while silencing of ABCA1 promoted the proliferation and inhibited the apoptosis of colon cancer LDL1 cells. Upregulation of specific miRNAs can contribute to the downregulation of tumor-suppressive genes. Thus, we aimed to ascertain whether ABCA1 is downregulated by overexpression of a specific miRNA in colon cancer. We screened microRNAs that may target ABCA1 by miRanda which is a commonly used prediction algorithm. We found that miR-183 targets the 3'UTR of ABCA1 mRNA. Subsequent experiments confirmed that miR-183 degraded ABCA1 mRNA in the colon cancer cells. Finally, we demonstrated that miR-183 promoted the proliferation and inhibited the apoptosis of colon cancer cells. Thus, we conclude that miR-183 promotes proliferation and inhibits apoptosis by degrading ABCA1 in colon cancer.

Ye P, Xing H, Lou F, et al.
Histone deacetylase 2 regulates doxorubicin (Dox) sensitivity of colorectal cancer cells by targeting ABCB1 transcription.
Cancer Chemother Pharmacol. 2016; 77(3):613-21 [PubMed] Related Publications
PURPOSE: Histone deacetylases (HDACs) have been shown to regulate cell cycle, differentiation, and apoptosis of colorectal cancer (CRC) cells, while their roles in drug sensitivity remain unclear. The objectives of the present study were to investigate the effects of HDAC2 on drug resistance of CRC cells.
METHODS: We measured the expression of class I HDACs (HDAC1, 2, 3, 8) in CRC and human normal colonic epithelial cells. Additionally, we inhibited HDAC2 via siRNA or overexpressed it via pcDNA/HDAC2 transfection to evaluate its roles in doxorubicin (Dox) sensitivity.
RESULTS: Our present study showed HDAC2 was significantly increased in CRC cell lines as compared to human normal colonic epithelial cells. Silencing of HDAC2 can obviously enhance the sensitivity of HCT-116 and SW480 cells to dDox. Further, knockdown of HDAC2 can significantly (p < 0.05) downregulate the expression of ABCB1, while not ABCG2, ABCC1, ABCA1, or ABCC2. Inhibition of HDAC2 decreased ABCB1 promoter activities and the phosphorylation of c-fos and c-Jun, which can directly interact with the ABCB1 promoter and then promote its transcription. Overexpression of HDAC2 by pcDNA/HDAC2 transfection significantly increased the sensitivity of CRC cells to Dox and upregulated the levels of P-gp, p-c-fos, and p-c-Jun.
CONCLUSIONS: Our data revealed that HDAC2 can regulate Dox sensitivity of CRC cells by targeting ABCB1 transcription. It suggested that HDAC2 might be an important target for CRC therapy. Further, the combination of HDAC2-specific inhibitor and anticancer drugs including Dox might be an efficiency approach to elevate the treatment outcome of CRC.

Sharma M, Tuaine J, McLaren B, et al.
Chemotherapy Agents Alter Plasma Lipids in Breast Cancer Patients and Show Differential Effects on Lipid Metabolism Genes in Liver Cells.
PLoS One. 2016; 11(1):e0148049 [PubMed] Free Access to Full Article Related Publications
Cardiovascular complications have emerged as a major concern for cancer patients. Many chemotherapy agents are cardiotoxic and some appear to also alter lipid profiles, although the mechanism for this is unknown. We studied plasma lipid levels in 12 breast cancer patients throughout their chemotherapy. Patients received either four cycles of doxorubicin and cyclophosphamide followed by weekly paclitaxel or three cycles of epirubicin, cyclophosphamide and 5'-fluorouracil followed by three cycles of docetaxel. Patients demonstrated a significant reduction (0.32 mmol/L) in high density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (apoA1) levels (0.18 g/L) and an elevation in apolipoprotein B (apoB) levels (0.15 g/L) after treatment. Investigation of the individual chemotherapy agents for their effect on genes involved in lipoprotein metabolism in liver cells showed that doxorubicin decreased ATP binding cassette transporter A1 (ABCA1) via a downregulation of the peroxisomal proliferator activated receptor γ (PPARγ) and liver X receptor α (LXRα) transcription factors. In contrast, ABCA1 levels were not affected by cyclophosphamide or paclitaxel. Likewise, apoA1 levels were reduced by doxorubicin and remained unaffected by cyclophosphamide and paclitaxel. Doxorubicin and paclitaxel both increased apoB protein levels and paclitaxel also decreased low density lipoprotein receptor (LDLR) protein levels. These findings correlate with the observed reduction in HDL-C and apoA1 and increase in apoB levels seen in these patients. The unfavourable lipid profiles produced by some chemotherapy agents may be detrimental in the longer term to cancer patients, especially those already at risk of cardiovascular disease (CVD). This knowledge may be useful in tailoring effective follow-up care plans for cancer survivors.

Wu TC, Lin YC, Chen HL, et al.
The enhancing effect of genistein on apoptosis induced by trichostatin A in lung cancer cells with wild type p53 genes is associated with upregulation of histone acetyltransferase.
Toxicol Appl Pharmacol. 2016; 292:94-102 [PubMed] Related Publications
Genistein has been shown to enhance the antitumor activity of trichostatin A (TSA) in human lung carcinoma A549 cells. However, whether the combined treatment exerts the same effect in other lung cancer cells is unclear. In the present study we first compared the enhancing effect of genistein on the antitumor effect of TSA in ABC-1, NCI-H460 (H460) and A549 cells. Second, we investigated whether the effects of genistein are associated with increased histone/non-histone protein acetylation. We found that the enhancing effect of genistein on cell-growth-arrest in ABC-1 cells (p53 mutant) was less than in A549 and H460 cells. Genistein enhanced TSA induced apoptosis in A549 and H460 cells rather than in ABC-1 cells. After silencing p53 expression in A549 and H460 cells, the enhancing effect of genistein was diminished. In addition, genistein increased TSA-induced histone H3/H4 acetylation in A549 and H460 cells. Genistein also increased p53 acetylation in H460 cells. The inhibitor of acetyltransferase, anacardic acid, diminished the enhancing effect of genistein on all TSA-induced histone/p53 acetylation and apoptosis. Genistein in combination with TSA increased the expression of p300 protein, an acetyltransferase, in A549 and NCI-H460 cells. Furthermore, we demonstrated that genistein also enhanced the antitumor effect of genistein in A549-tumor-bearing mice. Taken together, these results suggest that the enhancing effects of genistein on TSA-induced apoptosis in lung cancer cells were p53-dependent and were associated with histone/non-histone protein acetylation.

Kuder CH, Weivoda MM, Zhang Y, et al.
3-Deoxyschweinfurthin B Lowers Cholesterol Levels by Decreasing Synthesis and Increasing Export in Cultured Cancer Cell Lines.
Lipids. 2015; 50(12):1195-207 [PubMed] Free Access to Full Article Related Publications
The schweinfurthins have potent antiproliferative activity in multiple glioblastoma multiforme (GBM) cell lines; however, the mechanism by which growth is impeded is not fully understood. Previously, we demonstrated that the schweinfurthins reduce the level of key isoprenoid intermediates in the cholesterol biosynthetic pathway. Herein, we describe the effects of the schweinfurthins on cholesterol homeostasis. Intracellular cholesterol levels are greatly reduced in cells incubated with 3-deoxyschweinfurthin B (3dSB), an analog of the natural product schweinfurthin B. Decreased cholesterol levels are due to decreased cholesterol synthesis and increased cholesterol efflux; both of these cellular actions can be influenced by liver X-receptor (LXR) activation. The effects of 3dSB on ATP-binding cassette transporter 1 levels and other LXR targets are similar to that of 25-hydroxycholesterol, an LXR agonist. Unlike 25-hydroxycholesterol, 3dSB does not act as a direct agonist for LXR α or β. These data suggest that cholesterol homeostasis plays a significant role in the growth inhibitory activity of the schweinfurthins and may elucidate a mechanism that can be targeted in human cancers such as GBM.

Kachalaki S, Baradaran B, Majidi J, et al.
Reversal of chemoresistance with small interference RNA (siRNA) in etoposide resistant acute myeloid leukemia cells (HL-60).
Biomed Pharmacother. 2015; 75:100-4 [PubMed] Related Publications
BACKGROUND: Overexpression of ATP-binding cassette (ABC) drug transporters is a major barrier in the success of cancer chemotherapy. One way to overcome overexpression of ABC drug transporter-mediated chemoresistance in acute myeloid leukemia is to suppress ABC drug transporter genes expression by small interference RNA (siRNA). In this study was assessed the involvement of ABCB1 gene in the mechanisms of resistance to etoposide in AML cells.
METHODS: The etoposide-resistant HL-60 cells were generated by stepwise exposure increasing concentrations of etoposide. The etoposide-resistant HL-60 cells were transfected with siRNAs using Transfection Reagent. The ABCB1 mRNA expression were assessed by real-time quantitative PCR. The MDR1/P-gp levels were measured by Western blotting. The sensitivity of resistant HL-60 cells to etoposide after transfection was determined using MTT assay. Apoptosis of resistant HL-60 cells after transfection was detected by flow cytometer.
RESULTS: It was found that siRNA effectively inhibited ABCB1 expression at both mRNA and protein levels. Knockdown of the ABCB1 gene correlated with increased sensitivity of the resistant HL-60 cells to etoposide and was observed to lower the cytotoxic index (IC50 etoposide value) after transfection.
CONCLUSIONS: Our results indicate that product of the ABCB1 gene have effective role in resistance to etoposide in acute myeloid leukemia cells.

Kaneko T, Kanno C, Ichikawa-Tomikawa N, et al.
Liver X receptor reduces proliferation of human oral cancer cells by promoting cholesterol efflux via up-regulation of ABCA1 expression.
Oncotarget. 2015; 6(32):33345-57 [PubMed] Free Access to Full Article Related Publications
Liver X receptors (LXRs) contribute not only to maintain cholesterol homeostasis but also to control cell growth. However, the molecular mechanisms behind the LXR-mediated anti-proliferative effects are largely unknown. Here we show, by immunohistochemistry, that LXRα and LXRβ are differentially distributed in oral stratified squamous epithelia. By immunohistochemical and Western blot analyses, we also reveal that LXRα is abundantly expressed in human oral squamous cell carcinoma (HOSCC) tissues and cell lines. Cell counting, BrdU labeling and cell cycle assay indicated that LXR stimulation led to significant reduction of proliferation in HOSCC cells. Importantly, our study highlights, by using RNA interference, that the ATP-binding cassette transporter A1 (ABCA1)-accelerated cholesterol efflux is critical for the growth inhibitory action of LXRs in HOSCC cells. Moreover, we demonstrate that LXR activation reduces the growth of xenograft tumour of HOSCC cells in mice accompanied by the upregulation of ABCA1 expression and the decline of cholesterol levels in the tumour. These findings strongly suggested that targeting the LXR-regulated cholesterol transport, yielding in lowering intracellular cholesterol levels, could be a promising therapeutic option for certain types of cancers.

Sun DX, Liao GJ, Liu KG, Jian H
Endosialin‑expressing bone sarcoma stem‑like cells are highly tumor‑initiating and invasive.
Mol Med Rep. 2015; 12(4):5665-70 [PubMed] Free Access to Full Article Related Publications
It has been reported that the presence of a small group of cancer stem‑like 'side population (SP)' cells is responsible for therapy failure and tumor recurrence. The present study demonstrated that primary human osteosarcoma samples contained a SP of about 3.9% which overexpressed ABC transporters, including ABCA1, ABCB1, ABCB2 and ABCG2, which are associated with drug resistance and may have contributed to multi‑drug resistance of SP cells. Furthermore, these SP cells displayed increased expression of endosialin (CD248) and other stem cell surface proteins, including CD133, octamer‑binding transcription factor 3/4A, Nanog and Nestin, which are ultimately responsible for high self‑renewal and deregulated cell proliferation. In addition, it was shown that endosialin‑overexpressing SP cells were able to regenerate the tumor population and had a high invasive potential. Therefore, the present study suggested that osteosarcoma SP cells were cancer stem cells, as they displayed stem‑like properties; furthermore, endosialin may be a potential target to prevent osteosarcoma recurrence following chemotherapy.

Sehgal M, Gupta R, Moussa A, Singh TR
An Integrative Approach for Mapping Differentially Expressed Genes and Network Components Using Novel Parameters to Elucidate Key Regulatory Genes in Colorectal Cancer.
PLoS One. 2015; 10(7):e0133901 [PubMed] Free Access to Full Article Related Publications
For examining the intricate biological processes concerned with colorectal cancer (CRC), a systems biology approach integrating several biological components and other influencing factors is essential to understand. We performed a comprehensive system level analysis for CRC which assisted in unravelling crucial network components and many regulatory elements through a coordinated view. Using this integrative approach, the perceptive of complexity hidden in a biological phenomenon is extensively simplified. The microarray analyses facilitated differential expression of 631 significant genes employed in the progression of disease and supplied interesting associated up and down regulated genes like jun, fos and mapk1. The transcriptional regulation of these genes was deliberated widely by examining transcription factors such as hnf4, nr2f1, znf219 and dr1 which directly influence the expression. Further, interactions of these genes/proteins were evaluated and crucial network motifs were detected to associate with the pathophysiology of CRC. The available standard statistical parameters such as z-score, p-value and significance profile were explored for the identification of key signatures from CRC pathway whereas a few novel parameters representing over-represented structures were also designed in the study. The applied approach revealed 5 key genes i.e. kras, araf, pik3r5, ralgds and akt3 via our novel designed parameters illustrating high statistical significance. These novel parameters can assist in scrutinizing candidate markers for diseases having known biological pathways. Further, investigating and targeting these proposed genes for experimental validations, instead being spellbound by the complicated pathway will certainly endow valuable insight in a well-timed systematic understanding of CRC.

London E, Wassif CA, Horvath A, et al.
Cholesterol Biosynthesis and Trafficking in Cortisol-Producing Lesions of the Adrenal Cortex.
J Clin Endocrinol Metab. 2015; 100(10):3660-7 [PubMed] Free Access to Full Article Related Publications
CONTEXT: Cortisol-producing adenomas (CPAs), primary pigmented nodular adrenocortical disease (PPNAD), and primary macronodular adrenocortical hyperplasia (PMAH) cause ACTH-independent Cushing syndrome (CS). Investigation of their pathogenesis has demonstrated their integral link to the cAMP-dependent protein kinase signaling pathway.
OBJECTIVE: The aim of this study was to identify differences in cholesterol biosynthesis among different CS-causing adrenocortical tumors. Because of the concomitant associations of cAMP levels with cholesterol and with steroid biosynthesis, we hypothesized that benign cortisol-producing tumors would display aberration of these pathways.
DESIGN AND SETTING: Twenty-three patients with CPA, PPNAD, or PMAH who underwent adrenalectomy for CS were included in the study. Preoperative biochemical analyses were performed, and excised adrenal tissues were studied.
MAIN OUTCOME MEASURES: Serum, urinary hormone levels, serum lipid profiles, and anthropometric data were obtained preoperatively. Adrenal tissues were analyzed for total protein, cholesterol, and neutral sterol content by mass spectrometry and expression of HMGCR, LDLR, ABCA1, DHCR24, and STAR genes.
RESULTS: There were differences in cholesterol content and markers of cholesterol biosynthesis and metabolism that distinguished CPAs from PMAH and PPNAD; cholesterol, lathosterol, and lathosterol/cholesterol ratio were significantly higher in CPAs. ABCA1 mRNA was lower among CPAs compared to tissues from bilateral adrenocortical hyperplasia (PMAH and PPNAD), and mRNA expression of LDL-R, DCHR24, and HMGCR tended to be higher in CPA tumor tissues.
CONCLUSION: CPAs displayed characteristics of "cholesterol-starved" tissues when compared to PPNAD and PMAH and appeared to have increased intrinsic cholesterol production and uptake from the periphery, as well as decreased cholesterol efflux. This has implications for a potential new way of treating these tumors.

Zhang N, Lei J, Lei H, et al.
MicroRNA-101 overexpression by IL-6 and TNF-α inhibits cholesterol efflux by suppressing ATP-binding cassette transporter A1 expression.
Exp Cell Res. 2015; 336(1):33-42 [PubMed] Related Publications
BACKGROUND: MicroRNAs play key roles in regulating cholesterol homeostasis. Here, we investigated the role of microRNA-101 (miR-101) in regulating ATP-binding cassette transporter A1 (ABCA1) expression and cholesterol efflux under non-inflammatory and inflammatory conditions in human THP-1-derived macrophages and HepG2 hepatoblastoma cells.
METHODS: The cell lines were transfected with one of four lentiviral vectors: miR-101, miR-101 control, anti-miR-101, or anti-miR-101 control. A luciferase reporter assay was used to examine miR-101 binding to the 3' untranslated region (UTR) of ABCA1. Western blotting was conducted to assess ABCA1 protein expression. Cells were loaded with BODIPY-cholesterol and stained with oil red O to assess cholesterol efflux.
RESULTS: The luciferase activity assay revealed that wild-type miR-101 binding at site 2 significantly repressed ABCA1 3' UTR activity, suggesting that miR-101 directly targets the ABCA1 mRNA at site 2. In both cell lines, Western blotting revealed that miR-101 expression negatively regulates ABCA1 protein expression and significantly suppresses cholesterol efflux to ApoA1 under both low-density lipoprotein (LDL) and non-LDL conditions, which was confirmed by pronounced lipid inclusions visible by oil red O staining. In HepG2 cells, both IL-6 and TNF-α treatments produced significant miR-101 overexpression; however, in THP-1-derived macrophages, only IL-6 treatment produced significant miR-101 overexpression. Anti-mir-101 transfection under both IL-6 and TNF-α treatment conditions led to ABCA1 upregulation, indicating that miR-101 expression represses ABCA1 expression under inflammatory conditions.
CONCLUSIONS: miR-101 promotes intracellular cholesterol retention under inflammatory conditions through suppressing ABCA1 expression and suggests that the miR-101-ABCA1 axis may play an intermediary role in the development of NAFLD and vascular atherosclerosis.

Bernhart E, Damm S, Wintersperger A, et al.
Interference with distinct steps of sphingolipid synthesis and signaling attenuates proliferation of U87MG glioma cells.
Biochem Pharmacol. 2015; 96(2):119-30 [PubMed] Free Access to Full Article Related Publications
Glioblastoma is the most common malignant brain tumor, which, despite combined radio- and chemotherapy, recurs and is invariably fatal for affected patients. Members of the sphingolipid (SL) family are potent effectors of glioma cell proliferation. In particular sphingosine-1-phosphate (S1P) and the corresponding G protein-coupled S1P receptors transmit proliferative signals to glioma cells. To investigate the contribution to glioma cell proliferation we inhibited the first step of de novo SL synthesis in p53(wt) and p53(mut) glioma cells, and interfered with S1P signaling specifically in p53(wt) U87MG cells. Subunit silencing (RNAi) or pharmacological antagonism (using myriocin) of serine palmitoyltransferase (SPT; catalyzing the first committed step of SL biosynthesis) reduced proliferation of p53(wt) but not p53(mut) GBM cells. In U87MG cells these observations were accompanied by decreased ceramide, sphingomyelin, and S1P content. Inhibition of SPT upregulated p53 and p21 expression and induced an increase in early and late apoptotic U87MG cells. Exogenously added S1P (complexed to physiological carriers) increased U87MG proliferation. In line, silencing of individual members of the S1P receptor family decreased U87MG proliferation. Silencing and pharmacological inhibition of the ATP-dependent cassette transporter A1 (ABCA1) that facilitates S1P efflux in astrocytes attenuated U87MG growth. Glyburide-mediated inhibition of ABCA1 resulted in intracellular accumulation of S1P raising the possibility that ABCA1 promotes S1P efflux in U87MG glioma cells thereby contributing to inside-out signaling. Our findings indicate that de novo SL synthesis, S1P receptor-mediated signaling, and ABCA1-mediated S1P efflux could provide pharmacological targets to interfere with glioma cell proliferation.

Liu X, Gao Y, Zhao B, et al.
Discovery of microarray-identified genes associated with ovarian cancer progression.
Int J Oncol. 2015; 46(6):2467-78 [PubMed] Related Publications
Ovarian cancer is the most lethal cancer of female reproductive system. There is a consistent and urgent need to better understand its mechanism. In this study, we retrieved 186 genes that were dysregulated by at least 4-fold in 594 ovarian serous cystadenocarcinomas in comparison with eight normal ovaries, according to The Cancer Genome Atlas Ovarian Statistics data deposited in Oncomine database. DAVID analysis of these genes enriched two biological processes indicating that the cell cycle and microtubules might play critical roles in ovarian cancer progression. Among these 186 genes, 46 were dysregulated by at least 10-fold and their expression was further confirmed by the Bonome Ovarian Statistics data deposited in Oncomine, which covered 185 cases of ovarian carcinomas and 10 cases of normal ovarian surface epithelium. Six genes, including aldehyde dehydrogenase 1 family, member A2 (ALDH1A2), alcohol dehydrogenase 1B (class I), β polypeptide (ADH1B), NEL-like 2 (chicken) (NELL2), hemoglobin, β (HBB), ATP-binding cassette, sub-family A (ABC1), member 8 (ABCA8) and hemoglobin, α1 (HBA1) were identified to be downregulated by at least 10-fold in 779 ovarian cancers compared with 18 normal controls. Using mRNA expression profiles retrieved from microarrays deposited in the Gene Expression Omnibus Profiles database, RT-qPCR measurement and bioinformatics analysis, we further indicated that high expression of HBB might predict a poorer 5-year survival, high expression of ALDH1A2 and ABCA8 might predict a poor outcome; while ALDH1A2, ADH1B, HBB and ABCA8, in particular the former two genes, might be associated with drug resistance, and ALDH1A2 and NELL2 might contribute to invasiveness and metastasis in ovarian cancer. This study thus contributes to our understanding of the mechanism of ovarian cancer progression and development, and the six identified genes may be potential therapeutic targets and biomarkers for diagnosis and prognosis.

Lambrechts S, Lambrechts D, Despierre E, et al.
Genetic variability in drug transport, metabolism or DNA repair affecting toxicity of chemotherapy in ovarian cancer.
BMC Pharmacol Toxicol. 2015; 16:2 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: This study aimed to determine whether single nucleotide polymorphisms (SNPs) in genes involved in DNA repair or metabolism of taxanes or platinum could predict toxicity or response to first-line chemotherapy in ovarian cancer.
METHODS: Twenty-six selected SNPs in 18 genes were genotyped in 322 patients treated with first-line paclitaxel-carboplatin or carboplatin mono-therapy. Genotypes were correlated with toxicity events (anemia, neutropenia, thrombocytopenia, febrile neutropenia, neurotoxicity), use of growth factors and survival.
RESULTS: The risk of anemia was increased for variant alleles of rs1128503 (ABCB1, C > T; p = 0.023, OR = 1.71, 95% CI = 1.07-2.71), rs363717 (ABCA1, A > G; p = 0.002, OR = 2.08, 95% CI = 1.32-3.27) and rs11615 (ERCC1, T > C; p = 0.031, OR = 1.61, 95% CI = 1.04-2.50), while it was decreased for variant alleles of rs12762549 (ABCC2, C > G; p = 0.004, OR = 0.51, 95% CI = 0.33-0.81). Likewise, increased risk of thrombocytopenia was associated with rs4986910 (CYP3A4, T > C; p = 0.025, OR = 4.99, 95% CI = 1.22-20.31). No significant correlations were found for neurotoxicity. Variant alleles of rs2073337 (ABCC2, A > G; p = 0.039, OR = 0.60, 95% CI = 0.37-0.98), rs1695 (ABCC1, A > G; p = 0.017, OR = 0.55, 95% CI 0.33-0.90) and rs1799793 (ERCC2, G > A; p = 0.042, OR = 0.63, 95% CI 0.41-0.98) associated with the use of colony stimulating factors (CSF), while rs2074087 (ABCC1, G > C; p = 0.011, OR = 2.09, 95% CI 1.18-3.68) correlated with use of erythropoiesis stimulating agents (ESAs). Homozygous carriers of the rs1799793 (ERCC2, G > A) G-allele had a prolonged platinum-free interval (p = 0.016).
CONCLUSIONS: Our data reveal significant correlations between genetic variants of transport, hepatic metabolism, platinum related detoxification or DNA damage repair and toxicity or outcome in ovarian cancer.

Vargas T, Moreno-Rubio J, Herranz J, et al.
ColoLipidGene: signature of lipid metabolism-related genes to predict prognosis in stage-II colon cancer patients.
Oncotarget. 2015; 6(9):7348-63 [PubMed] Free Access to Full Article Related Publications
Lipid metabolism plays an essential role in carcinogenesis due to the requirements of tumoral cells to sustain increased structural, energetic and biosynthetic precursor demands for cell proliferation. We investigated the association between expression of lipid metabolism-related genes and clinical outcome in intermediate-stage colon cancer patients with the aim of identifying a metabolic profile associated with greater malignancy and increased risk of relapse. Expression profile of 70 lipid metabolism-related genes was determined in 77 patients with stage II colon cancer. Cox regression analyses using c-index methodology was applied to identify a metabolic-related signature associated to prognosis. The metabolic signature was further confirmed in two independent validation sets of 120 patients and additionally, in a group of 264 patients from a public database. The combined analysis of these 4 genes, ABCA1, ACSL1, AGPAT1 and SCD, constitutes a metabolic-signature (ColoLipidGene) able to accurately stratify stage II colon cancer patients with 5-fold higher risk of relapse with strong statistical power in the four independent groups of patients. The identification of a group of 4 genes that predict survival in intermediate-stage colon cancer patients allows delineation of a high-risk group that may benefit from adjuvant therapy, and avoids the toxic and unnecessary chemotherapy in patients classified as low-risk group.

Li G, Kim C, Kim J, et al.
Common Pesticide, Dichlorodiphenyltrichloroethane (DDT), Increases Amyloid-β Levels by Impairing the Function of ABCA1 and IDE: Implication for Alzheimer's Disease.
J Alzheimers Dis. 2015; 46(1):109-22 [PubMed] Related Publications
While early-onset familial Alzheimer's disease (AD) is caused by a genetic mutation, the vast majority of late-onset AD is likely caused by the combination of genetic and environmental factors. Unlike genetic studies, potential environmental factors affecting AD pathogenesis have not yet been thoroughly investigated. Among environmental factors, pesticides seem to be one of critical environmental contributors to late-onset AD. Recent studies reported that the serum and brains of AD patients have dramatically higher levels of a metabolite of dichlorodiphenyltrichloroethane (DDT). While these epidemiological studies provided initial clues to the environmental risks potentially contributing to disease pathogenesis, a functional approach is required to determine whether they actually have a causal role in disease development. In our study, we addressed this critical knowledge gap by investigating possible mechanisms by which DDT affects amyloid-β (Aβ) levels. We treated H4-AβPPswe or H4 cells with DDT to analyze its effect on Aβ metabolism using Aβ production, clearance, and degradation assays. We found that DDT significantly increased the levels of amyloid-β protein precursor (AβPP) and β-site AβPP-cleaving enzyme1 (BACE1), affecting Aβ synthesis pathway in H4-AβPPswe cells. Additionally, DDT impaired the clearance and extracellular degradation of Aβ peptides. Most importantly, we identified for the first time that ATP-binding cassette transporter A1 (ABCA1) and insulin-degrading enzyme (IDE) are the downstream target genes adversely affected by DDT. Our findings provide insight into the molecular mechanisms by which DDT exposure may increase the risk of AD, and it further supports that ABCA1 and IDE may be potential therapeutic targets.

Lv J, Fu Z, Shi M, et al.
Systematic analysis of gene expression pattern in has-miR-760 overexpressed resistance of the MCF-7 human breast cancer cell to doxorubicin.
Biomed Pharmacother. 2015; 69:162-9 [PubMed] Related Publications
BACKGROUND/AIMS: Chemoresistance of breast cancer is a growing problem and still a major clinical obstacle to successful treatment in clinical patients. miR-760 was significantly downregulated in chemoresistance breast cancer tissues compared to chemo-sensitive tissues in our previous study. However, the role of miR-760 in modulating drug resistance remains largely unexplored. In this study, we sought to determine the expression pattern of miR-760 targeted mRNAs, and explore their potential functions and participated-pathways in breast cancer drug resistance cells.
RESULTS: Compared to parental cell line MCF-7, miR-760 was downregulated by 6.15 folds in MCF-7/Adr cells. The qRT-PCR result showed that compared to miR-760 negative control cells group, miR-760 was up-regulated 15.817 folds after miR-760 lentiviral transfection in miR-760 mimics group. The microarray data showed that 270 genes were dysregulated over 2-fold change in MCF-7/Adr cells after miR-760 overexpressed, including 241 up-regulated and 29 downregulated genes. GO analysis result appeared that the predicted target genes of miR-760 mainly regulated DNA binding, protein binding, molecular function, nucleic acid binding, and so on; the pathway analysis data demonstrated that these target genes mainly involved in cell cycle, TGF-beta signaling pathway, mRNA processing reactome, G protein signaling, apoptosis, Wnt signaling pathway, and other signaling pathways. There were 3 predicted target genes (RHOB, ANGOTL4, ABCA1) of miR-760 were selected at a P value<0.05 and the fold enrichment was>40.
CONCLUSION: Our study explored the genes expression pattern after miR-760 overexpresssed, and confirmed 3 dominantly dysregulated genes, which could expand the insights into the miR-760 function and molecular mechanisms in drug resistance of breast cancer. This study might afford a comprehensive understanding of miR-760 as prognostic biomarkers during clinical treatment, and we supposed that the miR-760 expression levels in drug resistance carcinoma tissues could be pursued to develop new strategies for targeted therapies in chemoresistant breast cancer patients.

Ma Y, Li X, Cheng S, et al.
MicroRNA-106a confers cisplatin resistance in non-small cell lung cancer A549 cells by targeting adenosine triphosphatase-binding cassette A1.
Mol Med Rep. 2015; 11(1):625-32 [PubMed] Related Publications
MicroRNAs (miRNAs) have been discovered to have pivotal roles in regulating the drug resistance of various types of human cancer, including cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC). Fewer studies have explored the roles of miR-106a in NSCLC-cell resistance to DDP and its precise molecular mechanism has remained elusive. In the present study, whether miR-106a was able to mediate resistance of the lung cancer cell line A549 to DDP was investigated. Reverse transcription quantitative polymerase chain reaction was used to analyze miR-106a mRNA expression levels. miR-106a expression levels were upregulated in the DDP-resistant cell line A549/DDP compared with its parental cell line, A549. miR-106a-transfection induced DDP-resistance in A549 cells, while repression of miR-106a by anti-miR-106a in A549/DDP resulted in enhanced DDP cytotoxicity. Furthermore, it was discovered that the mechanism of miR-106a-induced DDP resistance involved the expression of adenosine triphosphatase-binding cassette, sub-family A, member 1 (ABCA1), as indicated by transfection of cells with short interfering RNA-ABCA1. The results of the present study suggested a novel mechanism underlying DDP-resistance in NSCLC.

Rama AR, Alvarez PJ, Madeddu R, Aranega A
ABC transporters as differentiation markers in glioblastoma cells.
Mol Biol Rep. 2014; 41(8):4847-51 [PubMed] Related Publications
UNLABELLED: Glioblastoma multiforme (GBM) is the most common primary malignant brain tumour, characterized by a high aggressivity, a huge heterogeneity attending a hierarchical model and resistance to therapy. Drug resistance has been correlated with the presence of the ABC efflux transporters which are able to exclude drugs for the cellular cytoplasm. In the nucleus of the GBM, initiating cells (ICs) can self-renew and give rise to cancer stem cells, which differ to the side population cells and the different cellular subtypes that form the mass around them. The ICs do not express or express ATP binding cassette (ABC) at very low levels, but this expression may increase with the differentiation process. We suggest that the differentiation process may be responsible of chemoresistance of the GBM cells. We compared three ABC transporters expression: ABCA1, MRP4 and MRP5, in the ICs obtained from 9 patients with GBM and their respective differentiated GBM cells. We show an overexpression of the three ABC transporters in the differentiated GBM cells in comparison to ICs.
IMPLICATIONS OF THE HYPOTHESIS: The blockade of these ABC transporters could help to improve the drug effectivity and thus reduce the tumour growth and prevent the tumour recurrence.

Hedditch EL, Gao B, Russell AJ, et al.
ABCA transporter gene expression and poor outcome in epithelial ovarian cancer.
J Natl Cancer Inst. 2014; 106(7) [PubMed] Free Access to Full Article Related Publications
BACKGROUND: ATP-binding cassette (ABC) transporters play various roles in cancer biology and drug resistance, but their association with outcomes in serous epithelial ovarian cancer (EOC) is unknown.
METHODS: The relationship between clinical outcomes and ABC transporter gene expression in two independent cohorts of high-grade serous EOC tumors was assessed with real-time quantitative polymerase chain reaction, analysis of expression microarray data, and immunohistochemistry. Associations between clinical outcomes and ABCA transporter gene single nucleotide polymorphisms were tested in a genome-wide association study. Impact of short interfering RNA-mediated gene suppression was determined by colony forming and migration assays. Association with survival was assessed with Kaplan-Meier analysis and log-rank tests. All statistical tests were two-sided.
RESULTS: Associations with outcome were observed with ABC transporters of the "A" subfamily, but not with multidrug transporters. High-level expression of ABCA1, ABCA6, ABCA8, and ABCA9 in primary tumors was statistically significantly associated with reduced survival in serous ovarian cancer patients. Low levels of ABCA5 and the C-allele of rs536009 were associated with shorter overall survival (hazard ratio for death = 1.50; 95% confidence interval [CI] =1.26 to 1.79; P = 6.5e-6). The combined expression pattern of ABCA1, ABCA5, and either ABCA8 or ABCA9 was associated with particularly poor outcome (mean overall survival in group with adverse ABCA1, ABCA5 and ABCA9 gene expression = 33.2 months, 95% CI = 26.4 to 40.1; vs 55.3 months in the group with favorable ABCA gene expression, 95% CI = 49.8 to 60.8; P = .001), independently of tumor stage or surgical debulking status. Suppression of cholesterol transporter ABCA1 inhibited ovarian cancer cell growth and migration in vitro, and statin treatment reduced ovarian cancer cell migration.
CONCLUSIONS: Expression of ABCA transporters was associated with poor outcome in serous ovarian cancer, implicating lipid trafficking as a potentially important process in EOC.

Ricardo E, Miranda IM, Faria-Ramos I, et al.
In vivo and in vitro acquisition of resistance to voriconazole by Candida krusei.
Antimicrob Agents Chemother. 2014; 58(8):4604-11 [PubMed] Free Access to Full Article Related Publications
Candida krusei is an important agent of opportunistic infections that often displays resistance to several antifungals. We describe here the in vivo acquisition of resistance to voriconazole (VRC) by C. krusei isolates recovered from a leukemia patient during a long period of VRC therapy. In order to mimic the in vivo development of VRC resistance, a susceptible C. krusei isolate was exposed daily to 1 μg/ml of VRC in vitro. Interestingly, after 5 days of exposure to VRC, a MIC of 4 μg/ml was achieved; this value remained constant after 25 additional days of treatment with VRC and also after 30 consecutive days of incubation in VRC-free medium. Our objective was to determine the associated molecular resistance mechanisms, such as expression of efflux pump genes and ERG11 gene mutations, among the resistant strains. Synergistic effects between the efflux blocker tacrolimus (FK506) and VRC were found in all of the resistant strains. Moreover, ABC1 gene expression increased over time in both the in vivo- and in vitro-induced resistant strains, in contrast to the ABC2 and ERG11 genes, whose expression was invariably lower and constant. ERG11 gene sequencing showed two different types of mutations, i.e., heterozygosity at T1389T/C, corresponding to synonymous mutations, in C. krusei strains and a missense mutation at position T418C, resulting in a change from Tyr to His, among resistant C. krusei clinical isolates. This study highlights the relevance of ATP-dependent efflux pump (namely, Abc1p) activity in VRC resistance and describes new mutations in the ERG11 gene among resistant C. krusei clinical isolates.

Thymiakou E, Kardassis D
Novel mechanism of transcriptional repression of the human ATP binding cassette transporter A1 gene in hepatic cells by the winged helix/forkhead box transcription factor A2.
Biochim Biophys Acta. 2014; 1839(6):526-36 [PubMed] Related Publications
ATP binding cassette transporter A1 (ABCA1) plays a key role in the biogenesis of HDL by promoting the efflux of cellular cholesterol and phospholipids to lipid free apoA-I. Mutations in the ABCA1 gene cause Tangier disease which is characterized by near or complete absence of circulating plasma HDL. In the present study we show that the winged helix/forkhead box containing transcription factor A2 (FOXA2) shown previously to play a role in glucose and bile acid homeostasis in the liver and in energy utilization in adipose tissue is a negative modulator of ABCA1 gene expression in hepatic cells. We show that the ABCA1 promoter contains three FOXA2 binding elements in the proximal region. Two of the sites are localized in a region of the ABCA1 promoter enriched in binding elements for transcriptional repressor proteins whereas the third site is the core of the TATA element of the ABCA1 promoter. Inhibition of FOXA2 binding to the ABCA1 promoter by site-directed mutagenesis or FOXA2 gene expression by siRNA was associated with increased ABCA1 promoter activity and protein levels. Overexpression of FOXA2 inhibited both the constitutive ABCA1 gene expression as well as ABCA1 gene induction by oxysterols and retinoids via nuclear receptors LXRα/RXRα. In summary, the present study identifies transcription factor FOXA2 as a negative modulator of ABCA1 gene expression in hepatic cells and reveals a novel mechanism of transcriptional repression by FOXA2 which involves the TATA element of the ABCA1 gene.

Huhn S, Bevier M, Pardini B, et al.
Colorectal cancer risk and patients' survival: influence of polymorphisms in genes somatically mutated in colorectal tumors.
Cancer Causes Control. 2014; 25(6):759-69 [PubMed] Related Publications
PURPOSE: The first two studies aiming for the high-throughput identification of the somatic mutation spectrum of colorectal cancer (CRC) tumors were published in 2006 and 2007. Using exome sequencing, they described 69 and 140 candidate cancer genes (CAN genes), respectively. We hypothesized that germline variants in these genes may influence CRC risk, similar to APC, which is causing CRC through germline and somatic mutations.
METHODS: After excluding the well-established CRC genes APC, KRAS, TP53, and ABCA1, we analyzed 35 potentially functional single-nucleotide polymorphisms (SNPs) in 10 CAN genes (OBSCN, MLL3, PKHD1, SYNE1, ERCC6, FBXW7, EPHB6/TRPV6, ELAC1/SMAD4, EPHA3, and ADAMTSL3) using KBiosciences Competitive Allele-Specific PCR™ genotyping assays. In addition to CRC risk (1,399 CRC cases, 838 controls), we also considered the influence of the SNPs on patients' survival (406 cases).
RESULTS: In spite of the fact that our in silico analyses suggested functional relevance for the studied genes and SNPs, our data did not support a strong influence of the studied germline variants on CRC risk and survival. The strongest association with CRC risk and survival was found for MLL3 (rs6464211, OR 1.50, p = 0.002, dominant model; HR 2.12, p = 0.020, recessive model). Two SNPs in EPHB6/TRPV6 (dominant model) showed marginal associations with survival (rs4987622 HR 0.58 p = 0.028 and rs6947538 HR 0.64, p = 0.036, respectively).
CONCLUSION: Although somatic mutations in the CAN genes have been related to the development and progression of various types of cancers in several next-generation sequencing or expression analyses, our study suggests that the studied potentially functional germline variants are not likely to affect CRC risk or survival.

Oiso S, Takayama Y, Nakazaki R, et al.
Factors involved in the cisplatin resistance of KCP‑4 human epidermoid carcinoma cells.
Oncol Rep. 2014; 31(2):719-26 [PubMed] Related Publications
KCP-4 is a cisplatin-resistant cell line established from human epidermoid carcinoma KB-3-1 cells. Although our previous study revealed that one of the mechanisms for cisplatin resistance in KCP-4 cells is the activation of NF-κB, its high resistance is considered to be induced by multiple mechanisms. In the present study, we explored other factors involved in the development of cisplatin resistance in KCP-4 cells. Since it has been reported that an unknown efflux pump exports cisplatin from KCP-4 cells in an ATP-dependent manner, we examined 48 types of ATP-binding cassette proteins as candidate cisplatin efflux transporters. The mRNA expression levels of ABCA1, ABCA3, ABCA7 and ABCB10 in KCP-4 cells were higher when compared to those in KB-3-1 cells. These expression levels in cisplatin-sensitive revertant KCP-4 cells (KCP-4R cells), were reduced in parallel with the sensitivity of these cells to cisplatin and their intracellular accumulation of cisplatin. Next, we investigated the occurrence of mutations in p53 in KCP-4 cells. We found a heterozygous missense mutation at codon 72 (p.Pro72Arg) in p53 of both KCP-4 and KB-3-1 cells, but the protein expression level of p53 in KCP-4 cells was higher when compared to that in KB-3-1. These results suggest that ABCA1, ABCA3, ABCA7 and ABCB10 are candidate genes for the cisplatin efflux transporter that is involved in the cisplatin resistance of KCP-4 cells, and that the mutation at codon 72 of p53 may contribute to the development of cisplatin resistance.

Szabó DR, Baghy K, Szabó PM, et al.
Antitumoral effects of 9-cis retinoic acid in adrenocortical cancer.
Cell Mol Life Sci. 2014; 71(5):917-32 [PubMed] Related Publications
The currently available medical treatment options of adrenocortical cancer (ACC) are limited. In our previous meta-analysis of adrenocortical tumor genomics data, ACC was associated with reduced retinoic acid production and retinoid X receptor-mediated signaling. Our objective has been to study the potential antitumoral effects of 9-cis retinoic acid (9-cisRA) on the ACC cell line NCI-H295R and in a xenograft model. Cell proliferation, hormone secretion, and gene expression have been studied in the NCI-H295R cell line. A complex bioinformatics approach involving pathway and network analysis has been performed. Selected genes have been validated by real-time qRT-PCR. Athymic nude mice xenografted with NCI-H295R have been used in a pilot in vivo xenograft model. 9-cisRA significantly decreased cell viability and steroid hormone secretion in a concentration- and time-dependent manner in the NCI-H295R cell line. Four major molecular pathways have been identified by the analysis of gene expression data. Ten genes have been successfully validated involved in: (1) steroid hormone secretion (HSD3B1, HSD3B2), (2) retinoic acid signaling (ABCA1, ABCG1, HMGCR), (3) cell-cycle damage (GADD45A, CCNE2, UHRF1), and the (4) immune response (MAP2K6, IL1R2). 9-cisRA appears to directly regulate the cell cycle by network analysis. 9-cisRA also reduced tumor growth in the in vivo xenograft model. In conclusion, 9-cisRA might represent a promising new candidate in the treatment of hormone-secreting adrenal tumors and adrenocortical cancer.

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.

Lee BH, Taylor MG, Robinet P, et al.
Dysregulation of cholesterol homeostasis in human prostate cancer through loss of ABCA1.
Cancer Res. 2013; 73(3):1211-8 [PubMed] Free Access to Full Article Related Publications
Recent epidemiologic data show that low serum cholesterol level as well as statin use is associated with a decreased risk of developing aggressive or advanced prostate cancer, suggesting a role for cholesterol in aggressive prostate cancer development. Intracellular cholesterol promotes prostate cancer progression as a substrate for de novo androgen synthesis and through regulation of AKT signaling. By conducting next-generation sequencing-based DNA methylome analysis, we have discovered marked hypermethylation at the promoter of the major cellular cholesterol efflux transporter, ABCA1, in LNCaP prostate cancer cells. ABCA1 promoter hypermethylation renders the promoter unresponsive to transactivation and leads to elevated cholesterol levels in LNCaP. ABCA1 promoter hypermethylation is enriched in intermediate- to high-grade prostate cancers and not detectable in benign prostate. Remarkably, ABCA1 downregulation is evident in all prostate cancers examined, and expression levels are inversely correlated with Gleason grade. Our results suggest that cancer-specific ABCA1 hypermethylation and loss of protein expression direct high intracellular cholesterol levels and hence contribute to an environment conducive to tumor progression.

Nieva C, Marro M, Santana-Codina N, et al.
The lipid phenotype of breast cancer cells characterized by Raman microspectroscopy: towards a stratification of malignancy.
PLoS One. 2012; 7(10):e46456 [PubMed] Free Access to Full Article Related Publications
Although molecular classification brings interesting insights into breast cancer taxonomy, its implementation in daily clinical care is questionable because of its expense and the information supplied in a single sample allocation is not sufficiently reliable. New approaches, based on a panel of small molecules derived from the global or targeted analysis of metabolic profiles of cells, have found a correlation between activation of de novo lipogenesis and poorer prognosis and shorter disease-free survival for many tumors. We hypothesized that the lipid content of breast cancer cells might be a useful indirect measure of a variety of functions coupled to breast cancer progression. Raman microspectroscopy was used to characterize metabolism of breast cancer cells with different degrees of malignancy. Raman spectra from MDA-MB-435, MDA-MB-468, MDA-MB-231, SKBR3, MCF7 and MCF10A cells were acquired with an InVia Raman microscope (Renishaw) with a backscattered configuration. We used Principal Component Analysis and Partial Least Squares Discriminant Analyses to assess the different profiling of the lipid composition of breast cancer cells. Characteristic bands related to lipid content were found at 3014, 2935, 2890 and 2845 cm(-1), and related to lipid and protein content at 2940 cm(-1). A classificatory model was generated which segregated metastatic cells and non-metastatic cells without basal-like phenotype with a sensitivity of 90% and a specificity of 82.1%. Moreover, expression of SREBP-1c and ABCA1 genes validated the assignation of the lipid phenotype of breast cancer cells. Indeed, changes in fatty acid unsaturation were related with the epithelial-to-mesenchymal transition phenotype. Raman microspectroscopy is a promising technique for characterizing and classifying the malignant phenotype of breast cancer cells on the basis of their lipid profiling. The algorithm for the discrimination of metastatic ability is a first step towards stratifying breast cancer cells using this rapid and reagent-free tool.

Vaughan CA, Frum R, Pearsall I, et al.
Allele specific gain-of-function activity of p53 mutants in lung cancer cells.
Biochem Biophys Res Commun. 2012; 428(1):6-10 [PubMed] Free Access to Full Article Related Publications
p53 mutations are mostly single amino acid changes resulting in expression of a stable mutant protein with "gain of function" (GOF) activity having a dominant oncogenic role rather than simple loss of function of wild-type p53. Knock-down of mutant p53 in human lung cancer cell lines with different endogenous p53 mutants results in loss of GOF activity as shown by lowering of cell growth rate. Two lung cancer cell lines, ABC1 and H1437, carrying endogenous mutants p53-P278S and -R267P, show reduction in growth rate on knock-down on p53 levels. However, whereas reduction of the p53 level induces loss of tumorigenicity in nude mice for ABC1 cells, it escalates tumorigenicity for H1437 cells. We have tested their transactivation potential on p53 target gene promoters by performing transient transcriptional assays in the p53-null H1299 lung cancer cell line. Interestingly, while the mutant p53 target promoter Axl was activated by both the mutants, the p21 promoter was activated by p53-R267P and wild-type p53 but not by p53-P278S; showing a clear difference in transcriptional activity between the two mutants. Our results demonstrate allele specificity between GOF p53 mutants and attempt to show that the specificity is dependent on the transactivation property of GOF p53; it also suggests importance of p21 activation in tumor suppression by p53.

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