Research IndicatorsGraph generated 29 August 2019 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. Tag cloud generated 29 August, 2019 using data from PubMed, MeSH and CancerIndex
Specific Cancers (5)
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).
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
Cancer Genome Anatomy Project, NCI
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: CSTB (cancer-related)
Teufel M, Seidel H, Köchert K, et al.Biomarkers Associated With Response to Regorafenib in Patients With Hepatocellular Carcinoma.
Gastroenterology. 2019; 156(6):1731-1741 [PubMed
] Related Publications
BACKGROUND & AIMS: In a phase 3 trial (RESORCE), regorafenib increased overall survival compared with placebo in patients with hepatocellular carcinoma (HCC) previously treated with sorafenib. In an exploratory study, we analyzed plasma and tumor samples from study participants to identify genetic, microRNA (miRNA), and protein biomarkers associated with response to regorafenib.
METHODS: We obtained archived tumor tissues and baseline plasma samples from patients with HCC given regorafenib in the RESORCE trial. Baseline plasma samples from 499 patients were analyzed for expression of 294 proteins (DiscoveryMAP) and plasma samples from 349 patients were analyzed for levels of 750 miRNAs (miRCURY miRNA PCR). Tumor tissues from 7 responders and 10 patients who did not respond (progressors) were analyzed by next-generation sequencing (FoundationOne). Forty-six tumor tissues were analyzed for expression patterns of 770 genes involved in oncogenic and inflammatory pathways (PanCancer Immune Profiling). Associations between plasma levels of proteins and miRNAs and response to treatment (overall survival and time to progression) were evaluated using a Cox proportional hazards model.
RESULTS: Decreased baseline plasma concentrations of 5 of 266 evaluable proteins (angiopoietin 1, cystatin B, the latency-associated peptide of transforming growth factor beta 1, oxidized low-density lipoprotein receptor 1, and C-C motif chemokine ligand 3; adjusted P ≤ .05) were significantly associated with increased overall survival time after regorafenib treatment. Levels of these 5 proteins, which have roles in inflammation and/or HCC pathogenesis, were not associated with survival independently of treatment. Only 20 of 499 patients had high levels and a reduced survival time. Plasma levels of α-fetoprotein and c-MET were associated with poor outcome (overall survival) independently of regorafenib treatment only. We identified 9 plasma miRNAs (MIR30A, MIR122, MIR125B, MIR200A, MIR374B, MIR15B, MIR107, MIR320, and MIR645) whose levels significantly associated with overall survival time with regorafenib (adjusted P ≤ .05). Functional analyses of these miRNAs indicated that their expression level associated with increased overall survival of patients with tumors of the Hoshida S3 subtype. Next-generation sequencing analyses of tumor tissues revealed 49 variants in 27 oncogenes or tumor suppressor genes. Mutations in CTNNB1 were detected in 3 of 10 progressors and VEGFA amplification in 1 of 7 responders.
CONCLUSION: We identified expression patterns of plasma proteins and miRNAs that associated with increased overall survival times of patients with HCC following treatment with regorafenib in the RESORCE trial. Levels of these circulating biomarkers and genetic features of tumors might be used to identify patients with HCC most likely to respond to regorafenib. ClinicalTrials.gov number NCT01774344. NCBI GEO accession numbers: mRNA data (NanoString): GSE119220; miRNA data (Exiqon): GSE119221.
Westermarck JTargeted therapies don't work for a reason; the neglected tumor suppressor phosphatase PP2A strikes back.
FEBS J. 2018; 285(22):4139-4145 [PubMed
] Related Publications
Therapies targeting tyrosine and serine/threonine kinases have raised enormous interest as potential cure for cancer patients in many common cancer types. However, except for the success story with BCR/ABL tyrosine kinase inhibitors in chronic myeloid leukemia (CML), critical review of results of a large number of clinical trials indicates that the clinical success with kinase inhibitors has been overall disappointing. These alarming results call for critical assessment of whether there is some fundamental flaw in the design of strategies to target phosphorylation-dependent oncogenic signaling for cancer therapy. This viewpoint debates on one potential, but thus far largely neglected, molecular explanation why inhibition of protein kinases is not sufficient for cancer cure. We note that the phosphorylation status, and thus the oncogenic potential of any given protein, is not regulated only by kinases, but rather by an intimate balance between kinases and their antagonist phosphatases. We further review the supporting functional evidence that for oncogenic transformation of human cells it is not enough to activate kinase signaling by activated kinases, if a group of counteracting tumor suppressor phosphatases is not inactivated. Based on these considerations, and a very recently emerged role of oncogenic function of a group of phosphatase inhibitor proteins as human oncoproteins, we propose that in order to efficiently inhibit phosphorylation-dependent signaling in cancer cells, and thus provide better therapeutic index, the kinase inhibitors should be combined with strategies to reactivate tumor suppressor phosphatases such as Protein Phosphatase 2A (PP2A).
Triple-negative breast cancer (TNBC) represents 10-20% of all human ductal adenocarcinomas and has a poor prognosis relative to other subtypes. Hence, new molecular targets for therapeutic intervention are necessary. Analyses of panels of human or mouse cancer lines derived from the same individual that differ in their cellular phenotypes but not in genetic background have been instrumental in defining the molecular players that drive the various hallmarks of cancer. To determine the molecular regulators of metastasis in TNBC, we completed a rigorous
Li Q, Zheng ZC, Ni CJ, et al.Correlation of Cystatin E/M with Clinicopathological Features and Prognosis in Triple-Negative Breast Cancer.
Ann Clin Lab Sci. 2018; 48(1):40-44 [PubMed
] Related Publications
BACKGROUND: Among all kinds of breast cancer, triple-negative breast cancer (TNBC) is the most aggressive, with the poorest prognosis and highest mortality rates. Thus, novel biomarkers that personalize the therapeutic regimen and evaluate prognosis for TNBC patients should be determined.
METHODS: We analyzed the cystatin E/M (CST6) expression profiles of 161 TNBC tissues and 14 noncancerous tissues through multiple statistical analyses. We also investigated the relationship of CST6 expression with clinical parameters and evaluated the prognostic value of CST6 in 161 TNBC patients.
RESULTS: CST6, a member of the cystatin superfamily, was remarkably more up-regulated in TNBC tissues than in adjacent normal breast tissues. High CST6 expression was frequently observed in white people and associated with a high risk of lymph-node metastasis. Cox regression analysis confirmed that the high CST6 expression was an independent predictor of disease-free survival in TNBC. Kaplan-Meier analysis further revealed that high CST6 expression caused a low disease-free survival rate.
CONCLUSION: CST6 is involved in the progression of TNBC and may act as a tumor-promoter gene. A systematic literature review shows that our study is the first to explore the relationship between CST6 and TNBC.
Kauko O, Westermarck JNon-genomic mechanisms of protein phosphatase 2A (PP2A) regulation in cancer.
Int J Biochem Cell Biol. 2018; 96:157-164 [PubMed
] Related Publications
Propagation of transient signals requires coordinated suppression of antagonistic phosphatase activity. Protein phosphatase 2A (PP2A) is a broad specificity serine/threonine phosphatase that functions as an antagonist of many signaling pathways associated with growth and proliferation, and endogenous inhibitory mechanisms suppress PP2A activity in response to mitogenic stimuli. These inhibitory mechanisms, including expression and activation of endogenous inhibitor proteins and phosphoregulation of PP2A subunits, are also engaged by aberrant constitutive activation of mitogenic pathways in cancer. Inhibition of PP2A activity has been shown to promote malignant transformation and endogenous inhibitory mechanisms of PP2A have been associated with malignant progression and prognosis in a wide range of cancers. Despite existence of recurrent mutations and other genetic and gene regulatory alterationsin PP2A genes, they collectively appear at relatively low frequency, and in only some cancer types. The non-genomic inhibition of PP2A activity by increased expression of endogenous PP2A inhibitor proteins greatly exceeds the frequency of genetic mutations of PP2A genes in human cancers. This feature makes PP2A an untypical tumor suppressor, and may have influenced its recognition as one of the critical human cell transformation mechanisms. We propose that non-genetic inhibition is the dominant mechanism causing loss of PP2A tumor suppressor function in cancer cells, possibly because these mechanisms do not elicit genomic instability associated with genetic loss of function of specific PP2A subunits.
Ma Y, Chen Y, Petersen IExpression and epigenetic regulation of cystatin B in lung cancer and colorectal cancer.
Pathol Res Pract. 2017; 213(12):1568-1574 [PubMed
] Related Publications
AIMS: Dysregulated expression of cystatin B (CSTB) has been implicated in various cancers. The aims of this study were to analyze the CSTB expression and investigate the epigenetic regulation of CSTB in lung and colon cancer cell lines, and also evaluate the clinical outcome of CSTB in primary lung and colorectal tumors.
METHODS: CSTB expression in lung and colon cancer cell lines was analyzed by real-time RT-PCR and western blotting. Epigenetic regulation of CSTB was examined by demethylation, deacetylation tests and bisulfite sequencing (BS). In primary lung and colorectal tumors, the protein expression of CSTB was evaluated by immunohistochemistry on tissue microarray.
RESULTS: CSTB was downregulated in lung cancer cell lines on mRNA and protein levels compared to human bronchial epithelial cells (HBEC). In colon cancer cell lines, CSTB was weakly expressed in Caco2, CX2 and HCT-16 and highly expressed in HT-29, WiDr, SW480 and HRT-18 on mRNA level compared to normal colonic fibroblast cells CCD33Co. After treatment with demethylation agent 5-aza-2'-deoxycytidine, increased CSTB mRNA expression was found in 7 out of 11 lung cancer cell lines including H226, H157, H2170, H1299, COLO677, A549 and H1975, while no obvious alteration was found in colon cancer cell lines. No DNA methylation could be found in the selected CpG islands in two types of cancer cell lines by bisulfite sequencing. In primary tumors, CSTB expression was significantly and inversely correlated with lung tumor stage (pN) and tumor grade (p=0.022 and 0.047, respectively). Kaplan-Meier survival curve revealed a tendency that lung tumors with high CSTB expression had a more favourable prognosis (p=0.062). In colorectal tumors, CSTB was not linked to any clinicopathological parameters including age, size of tumor, lymph node metastasis and tumor grading.
CONCLUSIONS: CSTB might be a potential prognostic marker for patients with primary lung cancer.
The ratio between proteases and their inhibitors is unbalanced in cancer. The cysteine protease inhibitor cystatin C is internalized by some cancer cells, which affects cellular properties. Here we aimed to investigate if uptake of cystatin C and the related inhibitor cystatin E/M occur in melanoma cell lines and to evaluate to what extent the uptake affects the legumain activity that is typically increased in melanoma. First we studied the basic expression, secretion, and intracellular content of all type 2 cystatins as well as expression and activity of their possible target enzymes legumain and cathepsin B in MDA-MB-435S, A375, and C8161 melanoma cells. Legumain activity was measureable in all cell lines, and of the potential legumain inhibitors, cystatin C, E/M, and F, cystatin C was the one mainly produced. All cells internalized cystatin C added to culture media, leading to increased intracellular cystatin C levels by 120-200%. Cystatin E/M was internalized as well but at a modest rate. The effects on intracellular legumain activity were nevertheless pronounced, probably because the cells lacked this inhibitor, and its affinity for legumain is 100-fold higher than that of cystatin C. Likewise, the low-degree uptake resulted in reduced migration and invasion of A375 cells in Matrigel to an extent comparable with the W106F variant of cystatin C with optimal uptake properties and resulting in much higher intracellular levels. Thus, cystatin E/M appears to be a good candidate to efficiently down-regulate the increased legumain activity, possibly important for the malignant phenotype of melanoma cells.
Zhang J, Shi Z, Huang J, Zou XCSTB Downregulation Promotes Cell Proliferation and Migration and Suppresses Apoptosis in Gastric Cancer SGC-7901 Cell Line.
Oncol Res. 2016; 24(6):487-494 [PubMed
] Related Publications
This study aimed to investigate the pivotal role of cystatin B (CSTB) in the development of gastric cancer and to explore its possible regulatory mechanism. Human gastric cancer SGC-7901 cells as a model in vitro were transfected with plasmid PCDNA3.1-CSTB and siRNA-CSTB using Lipofectamine 2000. Quantitative real-time PCR (qRT-PCR) and Western blotting were performed to determine the relative expression of CSTB and PI3K/Akt/mTOR pathway-related protein. Moreover, MTT assay, Transwell assay, and flow cytometry were used to assess cell proliferation, migration, and apoptosis, respectively. The results showed that CSTB was significantly downregulated in SGC-7901 cells compared with gastric epithelial cells. CSTB was successfully overexpressed and suppressed after cells were transfected with pc-CSTB and si-CSTB, respectively. Moreover, cell viability and migration were significantly decreased after being transfected with pc-CSTB when compared with the control group, while being obviously increased after transfection with si-CSTB. However, cell apoptosis was significantly induced after being transfected with pc-CSTB, while being obviously suppressed after transfection with si-CSTB. Besides, the expression levels of p-PI3K, p-Akt, and p-mTOR proteins were all significantly decreased in the pc-CSTB transfection group when compared with the control group, while being increased in the si-CSTB transfection group. Our findings suggest that CSTB downregulation may promote the development of gastric cancer by affecting cell proliferation and migration, and the PI3K/Akt/mTOR signaling pathway was activated in this process. CSTB may serve as a potential therapeutic target for gastric cancer.
Li Z, Heng J, Yan J, et al.Integrated analysis of gene expression and methylation profiles of 48 candidate genes in breast cancer patients.
Breast Cancer Res Treat. 2016; 160(2):371-383 [PubMed
] Related Publications
PURPOSE: Gene-specific methylation and expression have shown biological and clinical importance for breast cancer diagnosis and prognosis. Integrated analysis of gene methylation and gene expression may identify genes associated with biology mechanism and clinical outcome of breast cancer and aid in clinical management.
METHODS: Using high-throughput microfluidic quantitative PCR, we analyzed the expression profiles of 48 candidate genes in 96 Chinese breast cancer patients and investigated their correlation with gene methylation and associations with breast cancer clinical parameters.
RESULTS: Breast cancer-specific gene expression alternation was found in 25 genes with significant expression difference between paired tumor and normal tissues. A total of 9 genes (CCND2, EGFR, GSTP1, PGR, PTGS2, RECK, SOX17, TNFRSF10D, and WIF1) showed significant negative correlation between methylation and gene expression, which were validated in the TCGA database. Total 23 genes (ACADL, APC, BRCA2, CADM1, CAV1, CCND2, CST6, EGFR, ESR2, GSTP1, ICAM5, NPY, PGR, PTGS2, RECK, RUNX3, SFRP1, SOX17, SYK, TGFBR2, TNFRSF10D, WIF1, and WRN) annotated with potential TFBSs in the promoter regions showed negative correlation between methylation and expression. In logistics regression analysis, 31 of the 48 genes showed improved performance in disease prediction with combination of methylation and expression coefficient.
CONCLUSIONS: Our results demonstrated the complex correlation and the possible regulatory mechanisms between DNA methylation and gene expression. Integration analysis of methylation and expression of candidate genes could improve performance in breast cancer prediction. These findings would contribute to molecular characterization and identification of biomarkers for potential clinical applications.
Parisi C, Mastoraki S, Markou A, et al.Development and validation of a multiplex methylation specific PCR-coupled liquid bead array for liquid biopsy analysis.
Clin Chim Acta. 2016; 461:156-64 [PubMed
] Related Publications
BACKGROUND: Liquid biopsy is based on minimally invasive blood tests and has the potential to characterize the evolution of a solid tumor in real time, by extracting molecular information from circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Epigenetic silencing of tumor and metastasis suppressor genes plays a key role in survival and metastatic potential of cancer cells. Our group was the first to show the presence of epigenetic alterations in CTCs.
METHODS: We present the development and analytical validation of a highly specific and sensitive Multiplex Methylation Specific PCR-coupled liquid bead array (MMSPA) for the simultaneous detection of the methylation status of three tumor and metastasis suppressor genes (CST6, SOX17 and BRMS1) in liquid biopsy material (CTCs, corresponding ctDNA) and paired primary breast tumors.
RESULTS: In the EpCAM-positive CTCs fraction we observed methylation of: a) CST6, in 11/30(37%) and 11/30(37%), b) BRMS1 in 8/30(27%) and 11/30(37%) c) SOX17 in 8/30(27%) and 13/30(43%) early breast cancer patients and patients with verified metastasis respectively. In ctDNA we observed methylation of: a) CST6, in 5/30(17%) and 10/31(32%), b) BRMS1 in 8/30 (27%) and 8/31 (26%) c) SOX17 in 5/30(17%) and 13/31(42%) early breast cancer patients and patients with verified metastasis respectively.
CONCLUSIONS: Our results indicate a high cancerous load at the epigenetic level in EpCAM-positive CTCs fractions and corresponding ctDNA in breast cancer. The main principle of the developed methodology has the potential to be extended in a large number of gene-targets and be applied in many types of cancer.
We and others have shown that the cystatin E/M gene is inactivated in primary human tumors, pointing to its role as a tumor suppressor gene. However, the molecular mechanism of tumor suppression is not yet understood. Using plasmid-directed cystatin E/M gene overexpression, a lentivirus-mediated tetracycline-inducible vector system, and human papillomavirus 16 (HPV 16) E6 and E7 gene-immortalized normal human epidermal keratinocytes, we demonstrated intracellular and non-cell-autonomous apoptotic growth inhibition of tumor cell lines and that growth inhibition is associated with cytoplasmic retention of NF-κB. We further demonstrated decreased phosphorylation of IκB kinase (IKKβ) and IκBα in the presence of tumor necrosis factor alpha (TNF-α), confirming the role of cystatin E/M in the regulation of the NF-κB signaling pathway. Growth suppression of nude mouse xenograft tumors carrying a tetracycline-inducible vector system was observed with the addition of doxycycline in drinking water, confirming that the cystatin E/M gene is a tumor suppressor gene. Finally, immunohistochemical analyses of cervical carcinoma in situ and primary tumors have shown a statistically significant inverse relationship between the expression of cystatin E/M and cathepsin L and a direct relationship between the loss of cystatin E/M expression and nuclear expression of NF-κB. We therefore propose that the cystatin E/M suppressor gene plays an important role in the regulation of NF-κB.
Yang CC, Kuai XX, Gao WB, et al.Morroniside-Induced PP2A Activation Antagonizes Tau Hyperphosphorylation in a Cellular Model of Neurodegeneration.
J Alzheimers Dis. 2016; 51(1):33-44 [PubMed
] Related Publications
BACKGROUND: An accumulation of hyperphosphorylated tau in the brain is a hallmark of Alzheimer's disease (AD). Deficits in protein phosphatase 2A (PP2A) are associated with tau hyperphosphorylation in AD.
OBJECTIVE: To investigate the effects of morroniside (MOR), isolated from Cornus officinalis, on tau hyperphosphorylation and its underlying mechanisms related to PP2A.
METHODS: SK-N-SH cells were pretreated with 50-200 μM MOR for 24 h followed by 20 nM okadaic acid (OA) for 6 h. PP2Ac siRNA was transfected into HEK293 cells to determine the direct interaction of MOR with PP2A. Western blotting was used to measure the expression of proteins and enzymes. PP2A activity was measured by molybdenum blue spectrophotometry.
RESULTS: Pretreatment with MOR improved the cellular morphological damage and inhibited tau hyperphosphorylation in SK-N-SH cells induced by OA, a PP2A inhibitor. Moreover, MOR increased PP2A activity, concurrent with a decrease in the expression of demethylated PP2A at Leu309 and phosphorylated PP2A at Tyr307. MOR decreased protein phosphatase methylesterase 1 (PME-1) expression and the ratio of PME-1/leucine carboxyl methyltransferase 1 (LCMT-1). Furthermore, MOR treatment decreased the phosphorylation of Src at Tyr416, which regulates the phosphorylation of PP2A. MOR had no effect on PP2Ac expression and tau hyperphosphorylation in PP2Ac siRNA-transfected cells.
CONCLUSION: MOR attenuated OA-induced tau hyperphosphorylation via PP2A activation, and its mechanism might be related to the regulation of PP2Ac post-translational modification and upstream enzymes such as Src and PME-1.
Vini R, Juberiya AM, Sreeja SEvidence of pomegranate methanolic extract in antagonizing the endogenous SERM, 27-hydroxycholesterol.
IUBMB Life. 2016; 68(2):116-21 [PubMed
] Related Publications
The direct relationship between obesity and breast cancer has been elucidated recently with the identification of a cholesterol derivative 27-hydroxycholesterol (27HC), an endogenous SERM that can act through estrogen receptor (ER)-mediated mechanisms. Our recent research shed light on the possible SERM-like property of methanol extract of pericarp of pomegranate (PME) by using human breast (MCF-7, MDA-MB-231), endometrial (HEC-1A), cervical (SiHa, HeLa), ovarian (SKOV3) cancer cell lines, normal breast fibroblasts (MCF-10A) and also by in vivo models (ovariectomized Swiss albino mice). Our findings demonstrated that PME binds to ER and downregulates the Estrogen response elements (ERE)-mediated transcription in breast cancer cells without being agonistic in the uterine endometrium and has cardioprotective effects comparable to that of 17-β-estradiol. This preliminary work indicates the ability of PME to antagonize the activity of 27HC. We hypothesize that PME can compete with 27HC for ERα and reduce 27HC-induced proliferation of MCF-7 cells. Relevant estrogen-regulated genes such as pS2, PR and ERα were checked to evaluate the ability of PME to abrogate 27HC-induced genes. This study is significant, being the first report describing that bioactive components of the methanolic extract of pericarp of PME, a proven SERM could plausibly compete for 27HC.
Colorectal cancer (CRC) accounts for high mortality. So far, there is lack of markers capable of predicting which patients are at risk of aggressive course of the disease. Protein phosphatase-2A (PP2A) inhibitor proteins have recently gained interest as markers of more aggressive disease in certain cancers. Here, we report the role of PP2A inhibitor PME-1 in CRC. PME-1 expression was assessed from a rectal cancer patient cohort by immunohistochemistry, and correlations were performed for various clinicopathological variables and patient survival. Rectal cancer patients with higher cytoplasmic PME-1 protein expression (above median) had less recurrences (P = 0.003, n = 195) and better disease-free survival (DFS) than the patients with low cytoplasmic PME-1 protein expression (below median). Analysis of PPME-1 mRNA expression from TCGA dataset of colon and rectal adenocarcinoma (COADREAD) patient cohort confirmed high PPME1 expression as an independent protective factor predicting favorable overall survival (OS) (P = 0.005, n = 396) compared to patients with low PPME1 expression. CRC cell lines were used to study the effect of PME-1 knockdown by siRNA on cell survival. Contrary to other cancer types, PME-1 inhibition in CRC cell lines did not reduce the viability of cells or the expression of active phosphorylated AKT and ERK proteins. In conclusion, PME-1 expression predicts for a favorable outcome of CRC patients. The unexpected role of PME-1 in CRC in contrast with the oncogenic role of PP2A inhibitor proteins in other malignancies warrants further studies of cancer-specific function for each of these proteins.
Kao KJ, Tai CH, Chang WH, et al.A fluorescence in situ hybridization (FISH) microfluidic platform for detection of HER2 amplification in cancer cells.
Biosens Bioelectron. 2015; 69:272-9 [PubMed
] Related Publications
Over-expression/amplification of human epidermal growth factor receptors 2 (HER2) is a verified therapeutic biomarker for breast and gastric cancers. HER2 is also served as prognostic biomarker for gastric cancer because HER2 over-expression is associated with a 5-10% increase in cancer related death of gastric cancer. Cancer patients exhibiting HER2 over-expression can significantly improve their overall survival rates by taking the targeting drug Herceptin, which directly targets HER2. However, Herceptin has limited functions toward patients without HER2 over-expression and therefore it needs a highly specific and accurate detection method for diagnosis of HER2 over-expression. Currently, fluorescence in situ hybridization (FISH) technique is routinely employed to detect HER2 amplification. However, it is a labor-intensive, time-consuming hybridization process and is relatively costly. Furthermore, well-trained personnel are required to operate the delicate and complicate process. More importantly, it may take 1-2 days for well-trained personnel to perform a whole FISH assay. Given these limitations, we developed a new, integrated microfluidic FISH system capable of automating the entire FISH protocol which could be performed within a shorter period of time when compared to traditional methods. The microfluidic FISH chip consisted of a microfluidic control module for transportation of small amounts of fluids and a hybridization module to perform the hybridization of DNA probes and cells/tissue samples. With this approach, the new microfluidic chip was capable of performing the whole FISH assay within 20h. Four cell lines, two for non-HER2 amplification and two for HER2 amplification, and two clinical tissue samples, one for non-HER2 amplification and another for HER2 amplification, were used for verifications of the developed chip. Experimental data showed that there was no significant difference between the benchtop protocol and the chip-based protocol. Furthermore, the reagent consumption was greatly reduced (∼70% reduction). Especially, only 2-μl usage for FISH deoxyribonucleic acid (DNA) probe was used, which is five-fold reduction when compared with the traditional method. It is the first time that the entire FISH assay could be automated on a single chip by using tissue samples. The microfluidic system developed herein is therefore promising for rapid, automatic diagnosis of HER2-related diseases by detecting the HER2 gene with minimal consumption of samples and reagents and has a great potential for future pharmacogenetic diagnostics and therapy.
Li Z, Guo X, Wu Y, et al.Methylation profiling of 48 candidate genes in tumor and matched normal tissues from breast cancer patients.
Breast Cancer Res Treat. 2015; 149(3):767-79 [PubMed
] Related Publications
Gene-specific methylation alterations in breast cancer have been suggested to occur early in tumorigenesis and have the potential to be used for early detection and prevention. The continuous increase in worldwide breast cancer incidences emphasizes the urgent need for identification of methylation biomarkers for early cancer detection and patient stratification. Using microfluidic PCR-based target enrichment and next-generation bisulfite sequencing technology, we analyzed methylation status of 48 candidate genes in paired tumor and normal tissues from 180 Chinese breast cancer patients. Analysis of the sequencing results showed 37 genes differentially methylated between tumor and matched normal tissues. Breast cancer samples with different clinicopathologic characteristics demonstrated distinct profiles of gene methylation. The methylation levels were significantly different between breast cancer subtypes, with basal-like and luminal B tumors having the lowest and the highest methylation levels, respectively. Six genes (ACADL, ADAMTSL1, CAV1, NPY, PTGS2, and RUNX3) showed significant differential methylation among the 4 breast cancer subtypes and also between the ER +/ER- tumors. Using unsupervised hierarchical clustering analysis, we identified a panel of 13 hypermethylated genes as candidate biomarkers that performed a high level of efficiency for cancer prediction. These 13 genes included CST6, DBC1, EGFR, GREM1, GSTP1, IGFBP3, PDGFRB, PPM1E, SFRP1, SFRP2, SOX17, TNFRSF10D, and WRN. Our results provide evidence that well-defined DNA methylation profiles enable breast cancer prediction and patient stratification. The novel gene panel might be a valuable biomarker for early detection of breast cancer.
Takaya A, Peng WX, Ishino K, et al.Cystatin B as a potential diagnostic biomarker in ovarian clear cell carcinoma.
Int J Oncol. 2015; 46(4):1573-81 [PubMed
] Related Publications
Epithelial ovarian cancer (EOC) consists of four major subtypes: clear cell carcinoma (CCC), endometrioid adenocarcinoma (EA), mucinous adenocarcinoma (MA) and serous adenocarcinoma (SA). Relative to the other subtypes, the prognosis of CCC is poor due to a high recurrence rate and chemotherapy resistance, but CCC-specific biomarkers have yet to be identified. With the aim of identifying diagnostic and treatment biomarkers for CCC, we analyzed 96 cases of EOC (32 CCC, 13 EA, 19 MA, 32 SA) using liquid chromatography/mass spectrometry (LC/MS) followed by immunohistochemistry (IHC) and quantitative reverse transcription PCR (RT-qPCR). Semi-quantification of protein differences between subtypes showed upregulation of 150 proteins and downregulation of 30 proteins in CCC relative to the other subtypes. Based on hierarchical clustering that revealed a marked distinction in the expression levels of cystatin B (CYTB) and Annexin A4 (ANXA4) in CCC relative to the other subtypes, we focused the study on CYTB and ANXA4 expression in EOCs by IHC, RT-qPCR and western blot analyses using tissue specimens and cultured cells. As a result, compared to the other subtypes, CCC showed significantly high expression levels of CYTB and ANXA4 in the analyses. To examine the possibility of CYTB and ANXA4 as serum diagnostic biomarkers of CCC, we checked the protein levels in conditioned media and cell lysates using culture cells. Compared with the other subtypes, CCC cell lines showed a significantly higher level of expression of CYTB in both conditioned media and cell lysates, while ANXA4 showed a higher level of expression in cell lysates only. Our results demonstrate that CYTB and ANXA4 overexpression may be related to carcinogenesis and histopathological differentiation of CCC. CYTB may be a secreted protein, and may serve as a potential serum diagnostic biomarker of CCC, while ANXA4 may be useful as an intracellular marker.
BACKGROUND: Cancer genome and transcriptome analyses advanced our understanding of cancer biology. We performed transcriptome analysis of all known genes of peptidases also called proteases and their endogenous inhibitors in glioblastoma multiforme (GBM), which is one of the most aggressive and deadly types of brain cancers, where unbalanced proteolysis is associated with tumor progression.
METHODS: Comparisons were performed between the transcriptomics of primary GBM tumors and unmatched non-malignant brain tissue, and between GBM cell lines (U87-MG and U373) and a control human astrocyte cell line (NHA). Publicly-available data sets and our own datasets were integrated and normalized using bioinformatics tools to reveal protease and protease inhibitor genes with deregulated expression in both malignant versus non-malignant tissues and cells.
RESULTS: Of the 311 protease genes identified to be differentially expressed in both GBM tissues and cells, 5 genes were highly overexpressed, 2 genes coding for non-peptidase homologues transferrin receptor (TFRC) and G protein-coupled receptor 56 (GPR56), as well as 3 genes coding for the proteases endoplasmic reticulum aminopeptidase 2 (ERAP2), glutamine-fructose-6-phosphate transaminase 2 (GFPT2) and cathepsin K (CTSK), whereas one gene, that of the serine protease carboxypeptidase E (CPE) was strongly reduced in expression. Seventy five protease inhibitor genes were differentially expressed, of which 3 genes were highly overexpressed, the genes coding for stefin B (CSTB), peptidase inhibitor 3 (PI3 also named elafin) and CD74. Seven out of 8 genes (except CSTB) were validated using RT-qPCR in GBM cell lines. CTSK overexpression was validated using RT-qPCR in GBM tissues as well. Cathepsin K immunohistochemical staining and western blotting showed that only proteolytically inactive proforms of cathepsin K were overexpressed in GBM tissues and cells.
CONCLUSIONS: The presence of high levels of inactive proforms of cathepsin K in GBM tissues and cells indicate that in GBM the proteolytic/collagenolytic role is not its primary function but it plays rather a different yet unknown role.
D'Costa ZC, Higgins C, Ong CW, et al.TBX2 represses CST6 resulting in uncontrolled legumain activity to sustain breast cancer proliferation: a novel cancer-selective target pathway with therapeutic opportunities.
Oncotarget. 2014; 5(6):1609-20 [PubMed
] Free Access to Full Article Related Publications
TBX2 is an oncogenic transcription factor known to drive breast cancer proliferation. We have identified the cysteine protease inhibitor Cystatin 6 (CST6) as a consistently repressed TBX2 target gene, co-repressed through a mechanism involving Early Growth Response 1 (EGR1). Exogenous expression of CST6 in TBX2-expressing breast cancer cells resulted in significant apoptosis whilst non-tumorigenic breast cells remained unaffected. CST6 is an important tumor suppressor in multiple tissues, acting as a dual protease inhibitor of both papain-like cathepsins and asparaginyl endopeptidases (AEPs) such as Legumain (LGMN). Mutation of the CST6 LGMN-inhibitory domain completely abrogated its ability to induce apoptosis in TBX2-expressing breast cancer cells, whilst mutation of the cathepsin-inhibitory domain or treatment with a pan-cathepsin inhibitor had no effect, suggesting that LGMN is the key oncogenic driver enzyme. LGMN activity assays confirmed the observed growth inhibitory effects were consistent with CST6 inhibition of LGMN. Knockdown of LGMN and the only other known AEP enzyme (GPI8) by siRNA confirmed that LGMN was the enzyme responsible for maintaining breast cancer proliferation. CST6 did not require secretion or glycosylation to elicit its cell killing effects, suggesting an intracellular mode of action. Finally, we show that TBX2 and CST6 displayed reciprocal expression in a cohort of primary breast cancers with increased TBX2 expression associating with increased metastases. We have also noted that tumors with altered TBX2/CST6 expression show poor overall survival. This novel TBX2-CST6-LGMN signaling pathway, therefore, represents an exciting opportunity for the development of novel therapies to target TBX2 driven breast cancers.
BACKGROUND: Disseminated cutaneous malignant melanoma (CMM) is commonly unresponsive to standard chemotherapies, and there are as yet no predictive markers of therapy response.
METHODS: In the present study we collected fresh-frozen pretreatment lymph-node metastasis samples (n=14) from melanoma patients with differential response to dacarbazine (DTIC) or temozolomide (TMZ) chemotherapy, to identify proteins with an impact on treatment response. We performed quantitative protein profiling using tandem mass spectrometry and compared the proteome differences between responders (R) and non-responders (NR), matched for age, gender and histopathological type of CMM.
RESULTS: Biological pathway analyses showed several signalling pathways differing between R vs NR, including Rho signalling. Gene expression profiling data was available for a subset of the samples, and the results were compared with the proteomics data. Four proteins with differential expression between R and NR were selected for technical validation by immunoblotting (ISYNA1, F13A1, CSTB and S100A13), and CSTB and S100A13 were further validated on a larger sample set by immunohistochemistry (n=48). The calcium binding protein S100A13 was found to be significantly overexpressed in NR compared with R in all analyses performed.
CONCLUSIONS: Our results suggest that S100A13 is involved in CMM resistance to DTIC/TMZ.
Peters I, Dubrowinskaja N, Abbas M, et al.DNA methylation biomarkers predict progression-free and overall survival of metastatic renal cell cancer (mRCC) treated with antiangiogenic therapies.
PLoS One. 2014; 9(3):e91440 [PubMed
] Free Access to Full Article Related Publications
VEGF-targeted therapy increases both the progression-free (PFS) and overall survival (OS) of patients with metastasized renal cell cancer (mRCC). Identification of molecular phenotypes of RCC could improve risk-stratification and the prediction of the clinical disease course. We investigated whether gene-specific DNA hypermethylation can predict PFS and OS among patients undergoing anti-VEGF-based therapy. Primary tumor tissues from 18 patients receiving targeted therapy were examined retrospectively using quantitative methylation-specific PCR analysis of CST6, LAD1, hsa-miR-124-3, and hsa-miR-9-1 CpG islands. PFS and OS were analyzed for first-line and sequential antiangiogenic therapies using the log rank statistics. Sensitivity and specificity were determined for predicting first-line therapy failure. Hypermethylation of CST6 and LAD1 was associated with both a shortened PFS (log rank p = 0.009 and p = 0.004) and OS (p = 0.011 and p = 0.043). The median PFS observed for the high and low methylation groups of CST6 and LAD1 was 2.0 vs.11.4 months. LAD1 methylation had a specificity of 1.0 (95% CI 0.65-1.0) and a sensitivity of 0.73 (95% CI 0.43-0.90) for the prediction of first-line therapy. CST6 and LAD1 methylation are candidate epigenetic biomarkers showing unprecedented association with PFS and OS as well as specificity for the prediction of the response to therapy. DNA methylation markers should be considered for the prospective evaluation of larger patient cohorts in future studies.
Kennedy-Nasser AA, Ku S, Castillo-Caro P, et al.Ultra low-dose IL-2 for GVHD prophylaxis after allogeneic hematopoietic stem cell transplantation mediates expansion of regulatory T cells without diminishing antiviral and antileukemic activity.
Clin Cancer Res. 2014; 20(8):2215-25 [PubMed
] Free Access to Full Article Related Publications
PURPOSE: GVHD after allogeneic hematopoietic stem cell transplantation (alloSCT) has been associated with low numbers of circulating CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs). Because Tregs express high levels of the interleukin (IL)-2 receptor, they may selectively expand in vivo in response to doses of IL-2 insufficient to stimulate T effector T-cell populations, thereby preventing GVHD.
EXPERIMENTAL DESIGN: We prospectively evaluated the effects of ultra low-dose (ULD) IL-2 injections on Treg recovery in pediatric patients after alloSCT and compared this recovery with Treg reconstitution post alloSCT in patients without IL-2. Sixteen recipients of related (n = 12) or unrelated (n = 4) donor grafts received ULD IL-2 post hematopoietic stem cell transplantation (HSCT; 100,000-200,000 IU/m(2) ×3 per week), starting RESULTS: No grade 3/4 toxicities were associated with ULD IL-2. CD4(+)CD25(+)FoxP3(+) Tregs increased from a mean of 4.8% (range, 0%-11.0%) pre IL-2 to 11.1% (range, 1.2%-31.1%) following therapy, with the greatest change occurring in the recipients of matched related donor (MRD) transplants. No IL-2 patients developed grade 2-4 acute GVHD (aGVHD), compared with 4 of 33 (12%) of the comparator group who did not receive IL-2. IL-2 recipients retained T cells reactive to viral and leukemia antigens, and in the MRD recipients, only 2 of 13 (15%) of the IL-2 patients developed viral infections versus 63% of the comparator group (P = 0.022).
CONCLUSIONS: Hence, ULD IL-2 is well tolerated, expands a Treg population in vivo, and may be associated with a lower incidence of viral infections and GVHD.
Lung cancer in never smokers (NS) shows striking demographic, clinicopathological and molecular distinctions from the disease in smokers (S). Studies on selected genetic and epigenetic alterations in lung cancer identified that the frequency and profile of some abnormalities significantly differ by smoking status. This study compared the transcriptome of lung adenocarcinoma cell lines derived from S (n = 3) and NS (n = 3) each treated with vehicle (control), histone deacetylation inhibitor (trichostatin A) or DNA methylation inhibitor (5-aza-2'-deoxycytidine). Among 122 genes reexpressed following 5-aza-2'-deoxycytidine but not trichostatin A treatment in two or more cell lines (including 32 genes in S-only and 12 NS-only), methylation was validated for 80% (98/122 genes). After methylation analysis of 20 normal tissue samples and 14 additional non-small cell lung cancer cell lines (total 20), 39 genes frequently methylated in normal (>20%, 4/20) and 21 genes rarely methylated in non-small cell lung cancer (≤10%, 2/20) were excluded. The prevalence for methylation of the remaining 38 genes in lung adenocarcinomas from S (n = 97) and NS (n = 75) ranged from 8-89% and significantly differs between S and NS for CPEB1, CST6, EMILIN2, LAYN and MARVELD3 (P < 0.05). Furthermore, methylation of EMILIN2, ROBO3 and IGDCC4 was more prevalent in advanced (Stage II-IV, n = 61) than early (Stage I, n = 110) tumors. Knockdown of MARVELD3, one of the novel epigenetically silenced genes, by small interfering RNA significantly reduced anchorage-independent growth of lung cancer cells (P < 0.001). Collectively, this study has identified multiple, novel, epigenetically silenced genes in lung cancer and provides invaluable resources for the development of diagnostic and prognostic biomarkers.
Basal-like breast cancers frequently express aberrant DNA hypermethylation associated with concurrent silencing of specific genes secondary to DNMT3b overexpression and DNMT hyperactivity. DNMT3b is known to be post-transcriptionally regulated by microRNAs. The objective of the current study was to determine the role of microRNA dysregulation in the molecular mechanism governing DNMT3b overexpression in primary breast cancers that express aberrant DNA hypermethylation. The expression of microRNAs (miRs) that regulate (miR-29a, miR-29b, miR-29c, miR-148a and miR-148b) or are predicted to regulate DNMT3b (miR‑26a, miR-26b, miR-203 and miR-222) were evaluated among 70 primary breast cancers (36 luminal A-like, 13 luminal B-like, 5 HER2‑enriched, 16 basal-like) and 18 normal mammoplasty tissues. Significantly reduced expression of miR-29c distinguished basal-like breast cancers from other breast cancer molecular subtypes. The expression of aberrant DNA hypermethylation was determined in a subset of 33 breast cancers (6 luminal A-like, 6 luminal B-like, 5 HER2-enriched and 16 basal-like) through examination of methylation‑sensitive biomarker gene expression (CEACAM6, CDH1, CST6, ESR1, GNA11, MUC1, MYB, TFF3 and SCNN1A), 11/33 (33%) cancers exhibited aberrant DNA hypermethylation including 9/16 (56%) basal-like cancers, but only 2/17 (12%) non-basal-like cancers (luminal A-like, n=1; HER2-enriched, n=1). Breast cancers with aberrant DNA hypermethylation express diminished levels of miR-29a, miR-29b, miR-26a, miR-26b, miR-148a and miR-148b compared to cancers lacking aberrant DNA hypermethylation. A total of 7/9 (78%) basal-like breast cancers with aberrant DNA hypermethylation exhibit diminished levels of ≥6 regulatory miRs. The results show that i) reduced expression of miR-29c is characteristic of basal-like breast cancers, ii) miR and methylation-sensitive gene expression patterns identify two subsets of basal-like breast cancers, and iii) the subset of basal-like breast cancers with reduced expression of multiple regulatory miRs express aberrant DNA hypermethylation. Together, these findings strongly suggest that the molecular mechanism governing the DNMT3b-mediated aberrant DNA hypermethylation in primary breast cancer involves the loss of post-transcriptional regulation of DNMT3b by regulatory miRs.
Roll JD, Rivenbark AG, Sandhu R, et al.Dysregulation of the epigenome in triple-negative breast cancers: basal-like and claudin-low breast cancers express aberrant DNA hypermethylation.
Exp Mol Pathol. 2013; 95(3):276-87 [PubMed
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A subset of human breast cancer cell lines exhibits aberrant DNA hypermethylation that is characterized by hyperactivity of the DNA methyltransferase enzymes, overexpression of DNMT3b, and concurrent methylation-dependent silencing of numerous epigenetic biomarker genes. The objective of this study was to determine if this aberrant DNA hypermethylation (i) is found in primary breast cancers, (ii) is associated with specific breast cancer molecular subtypes, and (iii) influences patient outcomes. Analysis of epigenetic biomarker genes (CDH1, CEACAM6, CST6, ESR1, GNA11, MUC1, MYB, SCNN1A, and TFF3) identified a gene expression signature characterized by reduced expression levels or loss of expression among a cohort of primary breast cancers. The breast cancers that express this gene expression signature are enriched for triple-negative subtypes - basal-like and claudin-low breast cancers. Methylation analysis of primary breast cancers showed extensive promoter hypermethylation of epigenetic biomarker genes among triple-negative breast cancers, compared to other breast cancer subclasses where promoter hypermethylation events were less frequent. Furthermore, triple-negative breast cancers either did not express or expressed significantly reduced levels of protein corresponding to methylation-sensitive biomarker gene products. Together, these findings suggest strongly that loss of epigenetic biomarker gene expression is frequently associated with gene promoter hypermethylation events. We propose that aberrant DNA hypermethylation is a common characteristic of triple-negative breast cancers and may represent a fundamental biological property of basal-like and claudin-low breast cancers. Kaplan-Meier analysis of relapse-free survival revealed a survival disadvantage for patients with breast cancers that exhibit aberrant DNA hypermethylation. Identification of this distinguishing trait among triple-negative breast cancers forms the basis for development of new rational therapies that target the epigenome in patients with basal-like and claudin-low breast cancers.
Tzadok S, Caspin Y, Hachmo Y, et al.Directionality of noncoding human RNAs: how to avoid artifacts.
Anal Biochem. 2013; 439(1):23-9 [PubMed
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Inactivation of tumor suppressor and metastasis suppressor genes via epigenetic silencing is a frequent event in human cancers. Recent work has shown new mechanisms of epigenetic silencing, based on the occurrence of long noncoding promoter-spanning antisense and/or sense RNAs (lncRNAs), which constitute part of chromatin silencing complexes. Using reverse transcription polymerase chain reaction (RT-PCR), we have started to scan "triple negative" and Her2-overexpressing breast cancer cell lines for directional/bidirectional transcription through promoters of tumor suppressor and metastasis suppressor genes known to be epigenetically silenced in vivo. Surprisingly, we found that RT-PCR-amplified products were obtained at high frequency in the absence of exogenous primers. These amplified products resulted from RT priming via transcripts originating from promoter or upstream spanning regions. Consequently, this priming overruled directionality determination and led to false detection-identification of such lncRNAs. We show that this prevalent "no primer" artifact can be eliminated by treating the RNA preparations with periodate, performing RT reactions at highly elevated temperatures, or a combination of both. These experimental improvements enabled determination of the presence and directionality of individual promoter-spanning long noncoding RNAs with certainty. Examples for the BRMS1 metastasis suppressor gene, as well as RAR-β2 and CST6 human tumor suppressor genes, in breast carcinoma cell lines are presented.
Dimitrakopoulos L, Vorkas PA, Georgoulias V, Lianidou ESA closed-tube methylation-sensitive high resolution melting assay (MS-HRMA) for the semi-quantitative determination of CST6 promoter methylation in clinical samples.
BMC Cancer. 2012; 12:486 [PubMed
] Free Access to Full Article Related Publications
BACKGROUND: CST6 promoter is highly methylated in cancer, and its detection can provide important prognostic information in breast cancer patients. The aim of our study was to develop a Methylation-Sensitive High Resolution Melting Analysis (MS-HRMA) assay for the investigation of CST6 promoter methylation.
METHODS: We designed primers that amplify both methylated and unmethylated CST6 sequences after sodium bisulfate (SB) treatment and used spiked control samples of fully methylated to unmethylated SB converted genomic DNA to optimize the assay. We first evaluated the assay by analyzing 36 samples (pilot training group) and further analyzed 80 FFPES from operable breast cancer patients (independent group). MS-HRMA assay results for all 116 samples were compared with Methylation-Specific PCR (MSP) and the results were comparable.
RESULTS: The developed assay is highly specific and sensitive since it can detect the presence of 1% methylated CST6 sequence and provides additionally a semi-quantitative estimation of CST6 promoter methylation. CST6 promoter was methylated in 39/80 (48.75%) of FFPEs with methylation levels being very different among samples. MS-HRMA and MSP gave comparable results when all samples were analyzed by both assays.
CONCLUSIONS: The developed MS-HRMA assay for CST6 promoter methylation is closed tube, highly sensitive, cost-effective, rapid and easy-to-perform. It gives comparable results to MSP in less time, while it offers the advantage of additionally providing an estimation of the level of methylation.
Chimonidou M, Tzitzira A, Strati A, et al.CST6 promoter methylation in circulating cell-free DNA of breast cancer patients.
Clin Biochem. 2013; 46(3):235-40 [PubMed
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OBJECTIVES: We have recently shown that detection of CST6 promoter methylation in primary breast tumors can provide important prognostic information in patients with operable breast cancer and that CST6 promoter is also methylated in Circulating Tumor Cells (CTC). In this study we evaluated the presence of CST6 promoter methylation in cell-free DNA (cfDNA) circulating in plasma of breast cancer patients.
DESIGN AND METHODS: Our study material consisted of: a) a pilot testing group of 27 patients with stage I-III operable breast cancer, 46 patients with verified metastasis and 37 healthy donors and b) an independent cohort of 123 consecutive stage I-III operable breast cancer patients. Methylated and unmethylated CST6 promoter sequences were detected by using methylation-specific PCR (MSP). CST6 immunohistochemical detection was performed in 20 corresponding primary tumor tissues.
RESULTS: In the pilot testing group, CST6 promoter was methylated in 8/27 (29.6%) operable breast cancer patients, in 6/46 (13.0%) patients with verified metastasis but none of 37 healthy individuals (0%). In the independent cohort, 49/123 (39.8%) operable breast cancer patients were found positive. During the follow up period, 25/123 (20.3%) patients relapsed and 9/123 (7.3%) died. CST6 was methylated in cfDNA of 13/25 (52%) patients that relapsed and in 3/9 (33.3%) patients that died.
CONCLUSIONS: CST6 promoter is highly methylated in cfDNA of breast cancer patients, but not in healthy individuals. CST6 promoter methylation in cfDNA, should be prospectively validated as a novel plasma tumor biomarker for breast cancer in a large cohort of breast cancer patients.
Merwick A, O'Brien M, Delanty NComplex single gene disorders and epilepsy.
Epilepsia. 2012; 53 Suppl 4:81-91 [PubMed
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Epilepsy is a heterogeneous group of disorders, often associated with significant comorbidity, such as intellectual disability and skin disorder. The genetic underpinnings of many epilepsies are still being elucidated, and we expect further advances over the coming 5 years, as genetic technology improves and prices fall for whole exome and whole genome sequencing. At present, there are several well-characterized complex epilepsies associated with single gene disorders; we review some of these here. They include well-recognized syndromes such as tuberous sclerosis complex, epilepsy associated with Rett syndrome, some of the progressive myoclonic epilepsies, and novel disorders such as epilepsy associated with mutations in the PCDH 19 gene. These disorders are important in informing genetic testing to confirm a diagnosis and to permit better understanding of the variability in phenotype-genotype correlation.
Heterotrimeric protein phosphatase 2A (PP2A) consists of catalytic C (PP2Ac), structural A, and regulatory B-type subunits, and its dysfunction has been linked to cancer. Reversible methylation of PP2Ac by leucine carboxyl methyltransferase 1 (LCMT-1) and protein phosphatase methylesterase 1 (PME-1) differentially regulates B-type subunit binding and thus PP2A function. Polyomavirus middle (PyMT) and small (PyST) tumor antigens and SV40 small tumor antigen (SVST) are oncoproteins that block PP2A function by replacing certain B-type subunits, resulting in cellular transformation. Whereas the B-type subunits replaced by these oncoproteins seem to exhibit a binding preference for methylated PP2Ac, PyMT does not. We hypothesize that circumventing the normal cellular control of PP2A by PP2Ac methylation is a general strategy for ST- and MT-mediated transformation. Two predictions of this hypothesis are (1) that PyST and SVST also bind PP2A in a methylation-insensitive manner and (2) that down-regulation of PP2Ac methylation will activate progrowth and prosurvival signaling and promote transformation. We found that SVST and PyST, like PyMT, indeed form PP2A heterotrimers independently of PP2Ac methylation. In addition, reducing PP2Ac methylation through LCMT-1 knockdown or PME-1 overexpression enhanced transformation by activating the Akt and p70/p85 S6 kinase (S6K) pathways, pathways also activated by MT and ST oncoproteins. These results support the hypothesis that MT and ST oncoproteins circumvent cellular control of PP2A by methylation to promote transformation. They also implicate LCMT-1 as a negative regulator of Akt and p70/p85 S6K. Therefore, disruption of PP2Ac methylation may contribute to cancer, and modulation of this methylation may serve as an anticancer target.