EZH2 Single Nucleotide Variants (SNVs): Diagnostic and Prognostic Role in 10 Solid Tumor Types

The enhancer of zeste homolog 2 (EZH2) gene encodes a histone methyltransferase that is a catalytic subunit of the Polycomb repressive complex 2 (PRC2) group of proteins that act to repress gene expression. The EZH2 locus is rarely mutated in solid tumors and there is no comprehensive study of EZH2 single nucleotide variants (SNVs) associated with cancer susceptibility, prognosis and response to therapy. Here, for the first time, we review the functional roles of EZH2 DNA variants and propose a putative etiological role in 10 various solid tumors including: esophageal, hepatocellular, oral, urothelial, colorectal, lung and gastric cancers. In particular, we found that the C allele of the EZH2 variant rs3757441 is associated with increased EZH2 RNA expression and poorer prognosis (advanced stage) in at least two malignancies such as colorectal and hepatocellular carcinoma. This suggests that the C allele may be a functional risk variant in multiple malignant tumors. We therefore propose that the rs3757441 single nucleotide variant (SNV) be genotyped and real-time PCR assays be performed in large cohort studies in order to confirm this preliminary finding that could be useful for clinical practice

Long non-coding RNAs are key players in Prostate cancer tumorigenesis and drug resistance

"Long non-coding RNAs (lncRNAs) have been characterized as key players in several cancer-associated processes such as tumorigenesis and drug resistance. Emerging evidence indicates that lncRNAs affect initiation and progression of several cancers, including prostate cancer (PCa) and its advanced forms, such as metastatic castration resistant prostate cancer (mCRPC). Among others, H19 is one of the most studied oncogenic lncRNAs in cancer and has been associated with cancer tumorigenesis and progression, via mediating several pathways an acting in different mechanisms of action, including epigenetic and miRNA regulation. We have investigated lncRNA roles in PCa tumorigenesis by analysing the E006AA cell model. Emerging evidence has shown that parental E006AA are not tumorigenic in nude mice, while its derived E006AA-ht, is highly tumorigenic. Via high-throughput RNA sequencing we have shown that E006AA-ht overexpress different lncRNAs compared to E006AA. Interestingly, we found a high upregulation of H19 in E006AA-ht vs the parental cell line. Our in vitro validation has confirmed the sequencing data and further research could unravel a crucial role of H19 in PCa tumorigenesis, opening a new challenging chapter of lncRNAs research. We hypothesize that H19 could be involved in in vivo immunity suppression and our further studies aim at investigating H19 in this molecular and clinical context. Furthermore, we have studied lncRNAs as key players in cancer aggressiveness by using cellular models of mCRPC. From our studies, HORAS5 (i.e. linc00161) emerged as the most consistently upregulated lncRNA in CRPC patient-derived xenografts. This lncRNAs was previously associated with cancer drug-response in osteosarcoma, ovarian cancer and hepatocellular carcinoma. Our study has shown for the first time that HORAS5 promotes drug resistance in CRPC. After a preliminary drug screen, we have selected the chemotherapeutics cabazitaxel for further investigation. Via lentiviral-mediated overexpression and siRNA-based silencing we have regulated HORAS5 expression and analysed cell count and apoptosis of CRPC cells exposed to clinically achievable concentrations of cabazitaxel. The overexpression of HORAS5 increases cabazitaxel resistance, while HORAS5 silencing has an opposite effect, via inhibition of apoptosis. RNA sequencing and RT-qPCR revealed that BCL2A1 is the most upregulated transcript in HORAS5 overexpressing cells exposed to cabazitaxel, and that BCL2A1 silencing decreases cell count and increases caspase activity. Our data suggest that BCL2A1 expression is induced by HORAS5, thereby enhancing CRPC cells resistance to cabazitaxel. Transfection of CRPC cells with HORAS5-targeting ASOs can effectively silence this lncRNA and determine a decrease of cabazitaxel resistance. We have also shown that both HORAS5 and BCL2A1 upregulation results in decreased survival in PCa patients and samples from mCRPC patients treated with taxanes have upregulation of HORAS5. Overall, our studies bring novel insights into crucial roles of lncRNAs in PCa progression and aggressiveness making them emerging targets for cancer treatment at different stages.

LncRNA HORAS5 promotes taxane resistance in castration-resistant prostate cancer via a BCL2A1-dependent mechanism.

Background: Castration-resistant prostate cancer (CRPC) is an incurable malignancy. Long noncoding RNAs (lncRNAs) play key roles in drug resistance. Materials & methods: LncRNA HORAS5 role in cabazitaxel resistance (i.e., cell-count, IC50 and caspase activity) was studied via lentiviral-mediated overexpression and siRNA-based knockdown. Genes expression was analyzed with RNA-sequencing, reverse transcription quantitative PCR (RT-qPCR) and western blot. HORAS5 expression was queried in clinical database. Results: Cabazitaxel increased HORAS5 expression that upregulated BCL2A1, thereby protecting CRPC cells from cabazitaxel-induced apoptosis. BCL2A1 knockdown decreased cell-count and increased apoptosis in CRPC cells. HORAS5-targeting antisense oligonucleotide decreased cabazitaxel IC50. In CRPC clinical samples, HORAS5 expression increased upon taxane treatment. Conclusion:HORAS5 stimulates the expression of BCL2A1 thereby decreasing apoptosis and enhancing cabazitaxel resistance in CRPC cells

Identification of putative functional genes in breast and other cancers with potentially shared aetiology

Breast cancer is the 2nd most common cancer globally with nearly 1.7 million new cases of all cancers in women (1 in 4). Sporadic breast cancers studies have very few identified functional variants that underlie breast with other cancers such as lung and bone. The aim of this study was to identify DNA/RNA variants within genes that function in the development of breast cancer and other cancers with putative shared aetiology. Microarray datasets of primary breast cancer tissues were collected from the Gene Expression Omnibus (GEO). Tissue samples were categorised into histological and molecular subtypes. A total of 1638 histological and 1115 molecular breast cancer samples were compared to normal breast tissues 53 and 58 respectively using an empirical Bayes moderated t-test (P<0.01). 6,964 significantly expressed genes were identified in invasive ductal carcinoma (IDC), 6,867 ductal carcinoma in-situ (DCIS), 6,910 invasive lobular carcinoma (ILC), and 6,806 lobular carcinoma in-situ (LCIS). Within molecular subtypes 14,282 significantly expressed genes were identified in luminal A, 13,359 luminal B, 10,497 HER2, and 15,294 triple negative. We identified; PTPRC, ATP6VOC, NREP, FAM114A1, GNB2, RAD1, ZMYND11, SLC50A1, PEAR1, NUF2, and SMC4 to be putative novel genes underlying breast cancer. Many of the most significant genes identified in this study have been identified in other cancers (prostate, ovarian, colon, lung, and gastric) which may be due to underlying shared mechanisms in cancers. The potential of the genes identified may provide new biomarkers for diagnosis and treatment in breast and other cancers and pose potentially novel therapeutic treatments

LncRNA HORAS5 promotes taxane resistance in castration-resistant prostate cancer via a BCL2A1-dependent mechanism

Background: Castration-resistant prostate cancer (CRPC) is an incurable malignancy. Long noncoding RNAs (lncRNAs) play key roles in drug resistance. Materials & methods: LncRNA HORAS5 role in cabazitaxel resistance (i.e., cell-count, IC50 and caspase activity) was studied via lentiviral-mediated overexpression and siRNA-based knockdown. Genes expression was analyzed with RNA-sequencing, reverse transcription quantitative PCR (RT-qPCR) and western blot. HORAS5 expression was queried in clinical database. Results: Cabazitaxel increased HORAS5 expression that upregulated BCL2A1, thereby protecting CRPC cells from cabazitaxel-induced apoptosis. BCL2A1 knockdown decreased cell-count and increased apoptosis in CRPC cells. HORAS5-targeting antisense oligonucleotide decreased cabazitaxel IC50. In CRPC clinical samples, HORAS5 expression increased upon taxane treatment. Conclusion: HORAS5 stimulates the expression of BCL2A1 thereby decreasing apoptosis and enhancing cabazitaxel resistance in CRPC cells

LncRNA HORAS5 promotes taxane resistance in castration-resistant prostate cancer via a BCL2A1-dependent mechanism

Background: Castration-resistant prostate cancer (CRPC) is an incurable malignancy. Long noncoding RNAs (lncRNAs) play key roles in drug resistance. Materials & methods: LncRNA HORAS5 role in cabazitaxel resistance (i.e., cell-count, IC50 and caspase activity) was studied via lentiviral-mediated overexpression and siRNA-based knockdown. Genes expression was analyzed with RNA-sequencing, reverse transcription quantitative PCR (RT-qPCR) and western blot. HORAS5 expression was queried in clinical database. Results: Cabazitaxel increased HORAS5 expression that upregulated BCL2A1, thereby protecting CRPC cells from cabazitaxel-induced apoptosis. BCL2A1 knockdown decreased cell-count and increased apoptosis in CRPC cells. HORAS5-targeting antisense oligonucleotide decreased cabazitaxel IC50. In CRPC clinical samples, HORAS5 expression increased upon taxane treatment. Conclusion: HORAS5 stimulates the expression of BCL2A1 thereby decreasing apoptosis and enhancing cabazitaxel resistance in CRPC cells

Fine-Mapping <i>CASP8</i> Risk Variants in Breast Cancer

Background: Multiple genome-wide and candidate gene association studies have been conducted in search of common risk variants for breast cancer. Recent large meta analyses, consolidating evidence from these studies, have been consistent in highlighting the caspase-8 (CASP8) gene as important in this regard. To define a risk haplotype and map the CASP8 gene region with respect to underlying susceptibility variant/s, we screened four genes in the CASP8 region on 2q33-q34 for breast cancer risk. Methods: Two independent data sets from the United Kingdom and the United States, including 3,888 breast cancer cases and controls, were genotyped for 45 tagging single nucleotide polymorphisms (tSNP) in the expanded CASP8 region. SNP and haplotype association tests were carried out using Monte Carlo-based methods. Results: We identified a three-SNP haplotype across rs3834129, rs6723097, and rs3817578 that was significantly associated with breast cancer (P -6), with a dominant risk ratio and 95% CI of 1.28 (1.21-1.35) and frequency of 0.29 in controls. Evidence for this risk haplotype was extremely consistent across the two study sites and also consistent with previous data. Conclusion: This three-SNP risk haplotype represents the best characterization so far of the chromosome upon which the susceptibility variant resides. Impact: Characterization of the risk haplotype provides a strong foundation for resequencing efforts to identify the underlying risk variant, which may prove useful for individual-level risk prediction, and provide novel insights into breast carcinogenesis