Variants In Ovarian Cancer Research Articles

A spectrum of BRCA1 and BRCA2 germline deleterious variants in ovarian cancer in Russia.

Pathogenic variants (PVs) in BRCA1 and BRCA2 genes are essential biomarkers of an increased breast and ovarian cancer risk and tumor sensitivity to poly ADP ribose polymerase inhibitors. In Russia, eight PVs were thought to be the most common, among which BRCA1 c.5266dup is the most frequently identified one. We show the distribution of BRCA1/2 PVs identified with quantitative PCR and targeted next-generation sequencing in 1399 ovarian cancer patients recruited into the study from 72 Russian regions in 2015-2021. The most abundant PVs were c.5266dup (41.0%), c.4035del (7.0%), c.1961del (6.3%), c.181T > G (5.2%), c.3756_3759del (1.8%), c.3700_3704del (1.5%), and c.68_69del (1.5%), all found in BRCA1 and known to be recurrent in Russia. Several other frequent PVs were identified: c.5152 + 1G > T (1.2%), c.1687C > T (1.0%), c.4689C > G (0.9%), c.1510del (0.6%), c.2285_2286del (0.6%) in the BRCA1 gene; and c.5286T > G (1.2%), c.2808_2811del (0.8%), c.3847_3848del (0.8%), c.658_659del (0.7%), c.7879A > T (0.6%), in the BRCA2 gene. For the most common PV in the BRCA2 gene c.5286T > G, we suggested that it arose about 700years ago and is a new founder mutation. This study extends our knowledge about the BRCA1 and BRCA2 pathogenic variants variability.

Germline Testing and Somatic Tumor Testing for BRCA1/2 Pathogenic Variants in Ovarian Cancer: What Is the Optimal Sequence of Testing?

In 2020, ASCO recommended that all women with epithelial ovarian cancer have germline testing for BRCA1/2 mutations, and those without a germline pathogenic variant (PV) should have somatic tumor testing to determine eligibility for a poly (ADP-ribose) polymerase inhibitor. Consequently, the majority of patients with ovarian cancer will have both germline testing and somatic testing. An alternate strategy is tumor testing first and then germline testing if there is a PV in the tumor and/or significant family history. The objective was to conduct a cost-effectiveness analysis comparing the two testing strategies. The Markov model compared the costs (US dollars) and benefits of two testing strategies for newly diagnosed ovarian cancer: (1) ASCO strategy and (2) tumor testing triage for germline testing. Data were applied from SOLO-1, and costs were from wholesale acquisition prices, Medicare, and published sources. Sensitivity analyses accounted for uncertainty around various parameters. Monte Carlo simulation estimated the number tested and identified with germline and somatic BRCA PV for olaparib maintenance treatment annually in the US population. The ASCO strategy was more effective but more costly than tumor testing triage in identifying patients for olaparib, with an incremental cost-effectiveness ratio of $281,296 US dollars per progression-free life year gained. Assuming 10,000 eligible patients with ovarian cancer annually, Monte Carlo simulation yielded comparable numbers of patients with BRCA PV in the germline and tumor with the ASCO and tumor testing triage strategies (2,080 v 2,062, respectively), but substantially higher number of patients tested using the ASCO strategy (8,052 v 3,076). The ASCO strategy may identify more BRCA PVs but is not cost-effective. Tumor testing in epithelial ovarian cancer as triage for germline testing is the favored strategy in this health care system.

The Genetic and Molecular Analyses of RAD51C and RAD51D Identifies Rare Variants Implicated in Hereditary Ovarian Cancer from a Genetically Unique Population.

Simple SummaryWe have investigated RAD51C and RAD51D, hereditary ovarian cancer risk genes, in French Canadians of Quebec, Canada. This population of Western European origins exhibits a unique genetic landscape as shown by the frequency of carriers of specific rare pathogenic variants. As studying French Canadians could facilitate the identification and interpretation of clinically relevant variants, we performed genetic analyses of RAD51C and RAD51D in this population comprised of cases with a family history of ovarian cancer or those who developed it at a young age. We identified candidate variants and then investigated them in other French Canadian study groups. We performed biological assays and revealed possible mechanisms that would affect gene function. Using engineered cells expressing one of our protein variants, we also showed that they were more sensitive to a recently approved treatment for ovarian cancer. Our findings support the role of inherited variants in RAD51C and RAD51D in ovarian cancer.To identify candidate variants in RAD51C and RAD51D ovarian cancer (OC) predisposing genes by investigating French Canadians (FC) exhibiting unique genetic architecture. Candidates were identified by whole exome sequencing analysis of 17 OC families and 53 early-onset OC cases. Carrier frequencies were determined by the genetic analysis of 100 OC or HBOC families, 438 sporadic OC cases and 1025 controls. Variants of unknown function were assayed for their biological impact and/or cellular sensitivity to olaparib. RAD51C c.414G>C;p.Leu138Phe and c.705G>T;p.Lys235Asn and RAD51D c.137C>G;p.Ser46Cys, c.620C>T;p.Ser207Leu and c.694C>T;p.Arg232Ter were identified in 17.6% of families and 11.3% of early-onset cases. The highest carrier frequency was observed in OC families (1/44, 2.3%) and sporadic cases (15/438, 3.4%) harbouring RAD51D c.620C>T versus controls (1/1025, 0.1%). Carriers of c.620C>T (n = 7), c.705G>T (n = 2) and c.137C>G (n = 1) were identified in another 538 FC OC cases. RAD51C c.705G>T affected splicing by skipping exon four, while RAD51D p.Ser46Cys affected protein stability and conferred olaparib sensitivity. Genetic and functional assays implicate RAD51C c.705G>T and RAD51D c.137C>G as likely pathogenic variants in OC. The high carrier frequency of RAD51D c.620C>T in FC OC cases validates previous findings. Our findings further support the role of RAD51C and RAD51D in hereditary OC.

Case Review: Whole-Exome Sequencing Analyses Identify Carriers of a Known Likely Pathogenic Intronic BRCA1 Variant in Ovarian Cancer Cases Clinically Negative for Pathogenic BRCA1 and BRCA2 Variants.

Background: Detecting pathogenic intronic variants resulting in aberrant splicing remains a challenge in routine genetic testing. We describe germline whole-exome sequencing (WES) analyses and apply in silico predictive tools of familial ovarian cancer (OC) cases reported clinically negative for pathogenic BRCA1 and BRCA2 variants. Methods: WES data from 27 familial OC cases reported clinically negative for pathogenic BRCA1 and BRCA2 variants and 53 sporadic early-onset OC cases were analyzed for pathogenic variants in BRCA1 or BRCA2. WES data from carriers of pathogenic BRCA1 or BRCA2 variants were analyzed for pathogenic variants in 10 other OC predisposing genes. Loss of heterozygosity analysis was performed on tumor DNA from variant carriers. Results: BRCA1 c.5407-25T>A intronic variant, identified in two affected sisters and one sporadic OC case, is predicted to create a new splice effecting transcription of BRCA1. WES data from BRCA1 c.5407-25T>A carriers showed no evidence of pathogenic variants in other OC predisposing genes. Sequencing the tumor DNA from the variant carrier showed complete loss of the wild-type allele. Conclusions: The findings support BRCA1 c.5407-25T>A as a likely pathogenic variant and highlight the importance of investigating intronic sequences as causal variants in OC families where the involvement of BRCA1 is highly suggestive.

Role of alternatively spliced, pro-survival Protein Kinase C delta VIII (PKCδVIII) in ovarian cancer.

Ovarian cancer is the deadliest malignant disease in women. Protein Kinase C delta (PRKCD; PKCδ) is serine/threonine kinase extensively linked to various cancers. In humans, PKCδ is alternatively spliced to PKCδI and PKCδVIII. However, the specific function of PKCδ splice variants in ovarian cancer has not been elucidated yet. Hence, we evaluated their expression in human ovarian cancer cell lines (OCC): SKOV3 and TOV112D, along with the normal T80 ovarian cells. Our results demonstrate a marked increase in PKCδVIII in OCC compared to normal ovarian cells. Therefore, we elucidated the role of PKCδVIII and the underlying mechanism of its expression in OCC. Using overexpression and knockdown studies, we demonstrate that PKCδVIII increases cellular survival and migration in OCC. Further, overexpression of PKCδVIII in T80 cells resulted in increased expression of Bcl2 and knockdown of PKCδVIII in OCC decreased Bcl2 expression. Using co‐immunoprecipitations and immunocytochemistry, we demonstrate nuclear localization of PKCδVIII in OCC and further show increased association of PKCδVIII with Bcl2 and Bcl‐xL in OCC. Using PKCδ splicing minigene, mutagenesis, siRNA and antisense oligonucleotides, we demonstrate that increased levels of alternatively spliced PKCδVIII in OCC is regulated by splice factor SRSF2. Finally, we verified that PKCδVIII levels are elevated in samples of human ovarian cancer tissue. The data presented here demonstrate that the alternatively spliced, signaling kinase PKCδVIII is a viable target to develop therapeutics to combat progression of ovarian cancer.

Germline testing and somatic tumor testing for BRCA1/2 pathogenic variants in ovarian cancer: What is the optimal sequence of testing?

10585 Background: In 2020 ASCO recommended that all women with epithelial ovarian cancer have germline testing (GT) for BRCA1/2 mutations, and those without a germline pathogenic variant (PV) should have somatic tumor testing (TT), to determine eligibility for PARP inhibitor (PARPi) therapy (GT-TT strategy). An alternate strategy is to start with tumor testing first, and to conduct germline testing only in those with a PV in the tumor, or a significant family history (TT-GT strategy). The objective was to conduct a cost-effectiveness analysis comparing the 2 testing strategies. Methods: A Markov Monte Carlo simulation model compared the costs (USD) and benefits of the 2 testing strategies. According to local empiric data, a sufficient tissue sample for TT was available in 99% of cases, otherwise the patient would only have GT. Sensitivity of TT was 99% for detecting germline PV. Only those with BRCA1/2 PV were eligible for PARPi. Primary outcomes included the number of women eligible for PARPi, with progression-free years of life (PFLY) gained based on SOLO1 data, and the incremental cost-effectiveness ratio (ICER). Monte Carlo simulation estimated the number of women who would have GT and TT, and the total with germline or somatic BRCA1/2 PV eligible for PARPi. Sensitivity analyses accounted for uncertainty around various parameters. Results: The GT-TT strategy was more effective but more costly than TT-GT in identifying patients eligible for PARPi. Table summarizes the average lifetime costs, benefits, and Monte Carlo simulation estimates for 10,000 women diagnosed with advanced epithelial ovarian cancer annually in the USA. The incremental benefit from the GT-TT strategy would be achieved at substantial cost to the health care system, with an ICER of $119,340 per PFLY gained relative to the TT-GT strategy. The results were highly sensitive to the sensitivity of TT to detect germline PV, and the costs of GT and TT. Assuming that GT was less than 50% of the cost of TT, the sensitivity of TT had to exceed 98% for the TT-GT strategy to be cost-effective. Conclusions: Although the ASCO recommended strategy of BRCA germline testing followed by tumor testing for those without a pathogenic variant may be more effective in identifying ovarian cancer patients for PARP inhibitor therapy, it is more costly. The ASCO strategy is justified if the sensitivity of tumor testing is not sufficiently high. However, assuming high tumor testing performance rates, tumor testing first followed by germline testing if there is a PV in the tumor and/or family history is a cost-effective strategy.[Table: see text]

MassArray analysis of genomic susceptibility variants in ovarian cancer

Ovarian cancer (OC), a multifaceted and genetically heterogeneous malignancy is one of the most common cancers among women. The aim of the study is to unravel the genetic factors associated with OC and the extent of genetic heterogeneity in the populations of Jammu and Kashmir (J&K).Using the high throughput Agena MassARRAY platform, present case control study was designed which comprises 200 histopathological confirmed OC patients and 400 age and ethnicity matched healthy controls to ascertain the association of previously reported eleven single nucleotide polymorphisms (SNPs) spread over ten genes (DNMT3A, PIK3CA, FGFR2, GSTP1, ERCC5, AKT1, CASC16, CYP19A1, BCL2 and ERCC1) within the OC population of Jammu and Kashmir, India. The association of each variant was estimated using logistic regression analyses. Out of the 11 SNPs the odds ratio observed for three SNPs; rs2699887 was (1.72 at 95% CI: 1.19–2.48, p = 0.004), rs1695 was (1.87 at 95% CI: 1.28–2.71, p = 0.001), and rs2298881 was (0.66 at 95% CI: 0.46–0.96, p = 0.03) were found significantly associated with the OC after correction with confounding factors i.e. age & BMI. Furthermore, the estimation of interactive analyses was performed and odds ratio observed was 2.44 (1.72–3.47), p value < 0. 001 suggests that there was a strong existence of interplay between the selected genetic variants in OC, which demonstrate that interactive analysis highlights the role of gene–gene interaction that provides an insight among multiple little effects of various polymorphisms in OC.

Downregulation, Blood Type, Paternal Lineage, and Genetic Variants in Ovarian Cancer: A Call for Tumor Suppressor Genes Effectiveness

This article calls for a deeper look at the role of downregulation, blood type, paternal lineage, and genetic variants in ovarian cancer. While considering the importance of oncogenes, associated tumors, expression, or overexpression, signal transducers, and downregulation, it suggests that a viable platform for tumor suppressor genes effectiveness is needed for early detection. The role of DNA methylation to gene silencing, proteins, RNA alteration in the development of metastatic tissues in late stage of ovarian cancer, which require further elucidation and research, continue to suggest that methylation, and tumor suppressor genes from BRCA1 and BRCA2 mutations are exceptionally critical, and warrant further monitoring of genetic predispositions. The role of controlled induction of ARHI associated with the X chromosome, or loss of ARHI expression and faulty breast genes is another quest for added oncological inquiries. Additionally, arguments relating to ABO blood group and its association to epithelial ovarian cancer, throughout the literature postulate that ABO genes on chromosomes 9q34 are of high consideration. Reviewing blood type correlation with ovarian cancer, through a paternal lineage connection suggesting strong inheritance patterns in first degree relatives, suggests there is an X-linked variation, and X-chromosome variation in the process. A better understanding of cancer screening by means of genetic testing, as an early detection tool, and downregulation are worthy research lenses in the fight of ovarian cancer.

(Iso-)form Matters: Differential Implication of Vav3 Variants in Ovarian Cancer.

This commentary discusses recent results on the role of Vav3 in malignancy, in an effort to begin to define the underlying mechanisms and tissue context by which Vav3 proteins, in particular Vav3.1, promote the progression of malignant diseases and further modulate the response to clinically relevant drugs.

Assessment of the frequency of mitochondrial tRNA variants in patients with ovarian cancer

Background: Alternations in mitochondrial DNA (mtDNA) have long been proposed to be involved in the pathogenesis of ovarian cancer (OC). However, the allele frequency of mitochondrial tRNA (mttRNA) variants in OC remains largely understood. Objective: To explore the potential association between mt-tRNA variants and OC. Methods: 95 OC patients and 50 control subjects were participated in this study. The 22 mt-tRNA genes were PCR amplified and subsequently sequenced by ABI-3700 automatic DNA sequencer. Moreover, we used phylogenetic approach to determine the pathogenic status of these mt-tRNA variants. Results: We identified 4 mt-tRNA variants: the tRNAThr A15951G; tRNAHis G12192A; tRNAGlu A14693G and tRNALeu(UUR) A3302G, whereas these tRNA variants were absent in healthy controls. Moreover, these variants localized at positions which were highly conserved between different species, and may cause the failure in mt-tRNAs metabolism, consequently result in mitochondrial dysfunction that responsible for OC. Conclusions: Variations in mt-tRNAs may be associated with OC.

Differential expression of estrogen receptor subtypes and variants in ovarian cancer: effects on cell invasion, proliferation and prognosis

BackgroundDue to the presence of both classical estrogen receptor (ERα) and another ER subtype (ERβ) in ovarian cancer, hormonal treatment is an attractive option. However, response to tamoxifen in ovarian cancer is modest. The presence of ERβ variants further complicated the issue. We have recently shown that specifically targeting ER subtypes using selective ER modulators showed opposing functions of ER subtypes on cell growth. In the present study, the clinical significance of ERα and ERβ variants (β1, β2 and β5) and the functional effects of ERβ2 and ERβ5 in ovarian cancer was investigated.MethodsERα, ERβ1, ERβ2 and ERβ5 expression were evaluated by immunohistochemistry in 106 ovarian cancer tissues. The association between ERs expression and clinicopathological parameters or prognosis was analyzed. Ectopic expression of ERβ2 and ERβ5 followed by functional assays were performed in ovarian cancer cell lines in order to detect their effects on cell invasion and proliferation.ResultsWe found significantly higher nuclear (n)ERα and nERβ5 and lower cytoplasmic (c)ERα expression in advanced cancers. Significantly lower ERβ1 expression was also detected in high grade cancers. Significant loss of nERα and cERβ2 expression were observed in clear cell histological subtypes. Higher nERβ5 and lower cERβ5 expression were associated with serous/clear cell subtypes, poor disease-free and overall survival. Positive cERα and higher cERβ1 expression were significantly associated with better disease-free and overall survival. Furthermore, we found nERβ5 as an independent prognostic factor for overall survival. Functionally, overexpression of ERβ5 enhanced ovarian cancer cell migration, invasion and proliferation via FAK/c-Src activation whereas ERβ2 induced cell migration and invasion.ConclusionsSince tamoxifen binds to both ERα and ERβ1 which appear to bear opposing oncogenic roles, the histotypes-specific expression pattern of ERs indicates that personalized treatment for women based on ERs expression using selective estrogen receptor modulators may improve response rate. This study also suggests nERβ5 as a potential prognostic marker and therapeutic target in ovarian cancer.

Integrated analysis of germline and somatic variants in ovarian cancer

We report the first large-scale exome-wide analysis of the combined germline-somatic landscape in ovarian cancer. Here we analyze germline and somatic alterations in 429 ovarian carcinoma cases and 557 controls. We identify 3,635 high confidence, rare truncation and 22,953 missense variants with predicted functional impact. We find germline truncation variants and large deletions across Fanconi pathway genes in 20% of cases. Enrichment of rare truncations is shown in BRCA1, BRCA2, and PALB2. Additionally, we observe germline truncation variants in genes not previously associated with ovarian cancer susceptibility (NF1, MAP3K4, CDKN2B, and MLL3). Evidence for loss of heterozygosity was found in 100% and 76% of cases with germline BRCA1 and BRCA2 truncations respectively. Germline-somatic interaction analysis combined with extensive bioinformatics annotation identifies 237 candidate functional germline truncation and missense variants, including 2 pathogenic BRCA1 and 1 TP53 deleterious variants. Finally, integrated analyses of germline and somatic variants identify significantly altered pathways, including the Fanconi, MAPK, and MLL pathways.

Profiling of linker histone variants in ovarian cancer

H1 linker histones play a key role in facilitating higher order chromatin folding. Emerging evidence suggests that H1 and its multiple variants are important epigenetic factors in modulating chromatin function and gene expression. Ovarian cancer is a devastating disease, ranking the fifth leading cause of all women cancer death due to its poor prognosis and difficulty in early diagnosis. Although epigenetic alterations in ovarian cancers are being appreciated in general, the role of H1 has not been explored. Here, using quantitative RT-PCR assays, we systematically examined the expression of 7 H1 genes in 33 human epithelial ovarian tumors. Whereas the expression of H1.3 was markedly increased, the expression of H10, H1.1, H1.4 and H1x were significantly reduced in malignant adenocarcinomas compared with benign adenomas. Strikingly, ovarian adenocarcinomas and adenomas exhibited characteristic expression patterns, and expression profiling of 7 H1 genes in tumor samples discriminated adenocarcinomas vs. adenomas with high accuracy. These findings indicate that the expression of H1 variants is exquisitely regulated and may serve as potential epigenetic biomarkers for ovarian cancer.

Silencing Survivin Splice Variant 2B Leads to Antitumor Activity in Taxane-Resistant Ovarian Cancer

To study the role of survivin and its splice variants in taxane-resistant ovarian cancer. We assessed the mRNA levels of survivin splice variants in ovarian cancer cell lines and ovarian tumor samples. siRNAs targeting survivin were designed to silence all survivin splice variants (T-siRNA) or survivin 2B (2B-siRNA) in vitro and orthotopic murine models of ovarian cancer. The mechanism of cell death was studied in taxane-resistant ovarian cancer cells and in tumor sections obtained from different mouse tumors. Taxane-resistant ovarian cancer cells express higher survivin mRNA levels than their taxane-sensitive counterparts. Survivin 2B expression was significantly higher in taxane-resistant compared with -sensitive cells. Silencing survivin 2B induced growth inhibitory effects similar to silencing total survivin in vitro. In addition, survivin 2B-siRNA incorporated into DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) nanoliposomes resulted in significant reduction in tumor growth (P < 0.05) in orthotopic murine models of ovarian cancer, and these effects were similar to T-siRNA-DOPC. The antitumor effects were further enhanced in combination with docetaxel chemotherapy (P < 0.01). Finally, we found a significant association between survivin 2B expression and progression-free survival in 117 epithelial ovarian cancers obtained at primary debulking surgery. These data identify survivin 2B as an important target in ovarian cancer and provide a translational path forward for developing new therapies against this target.

Abstract 677: Targeting the survivin splice variant 2β in taxane-resistant ovarian cancer

Abstract Survivin, a protein highly expressed in human cancers is involved in both control of cell cycle progression and inhibition of apoptosis. Transcription of the survivin gene locus (BIRC-5) yields at least 5 alternative splice variants that have been designed survivn-WT, survivin-ΔEx3, survivin-2β, surivivn-3β, and survivin 2α. It has been shown that the survivin splice variants have different expression levels and subcellular localization patterns that could be associated with unique functional properties. Whereas the effects of survivin on apoptosis and mitosis have been extensively studied and explored therapeutically, the role of specific survivin splice variants in ovarian cancer has not been investigated. Our compelling studies indicate that, compared with their taxane-sensitive counterparts, taxane-resistant ovarian cancer cells express higher survivin mRNA (particularly the WT, ΔEx3 and 2β isoforms) levels. Studies have shown that survivin-2β has proapoptotic properties: whereas, forced expression of survivin-2β sensitized cells to taxane-induced apoptosis, small-interference RNA (siRNA)-based silencing of survivin-2β protected cells from cells from apoptotic cell death. We have observed opposite results: siRNA-based silencing of survivin-2β induced cell growth arrest and apoptosis of taxane-resistant ovarian cancer cells. Furthermore, liposomes-encapsulated siRNA targeting survivin-2β inhibited tumor growth in orthotopic murine models of ovarian cancer. The anti-tumor effect was further increased by combination with docetaxel. Finally, we found a significant association of survivin-2β expression with progression free survival in the 117 epithelial ovarian cancers obtained at primary debulking therapy. Further studies are necessary to clarify the role of survivin-2β in ovarian cancer. The key finding from our study is that survive-2β is present in a substantial proportion of ovarian cancers, and is predictive of decreased progression-free survival (PFS) of ovarian cancer patients. These studies also show the feasibility of survivin-2β-targeting siRNA liposomal as a clinically applicable therapeutic modality for taxane-resistant ovarian cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 677.

Serous psammocarcinoma of the ovary: An unusual finding

Background. Serous psammocarcinoma of the ovary is a rare and infrequently described variant of ovarian cancer, characterized histologically by the pervasive presence of psammoma bodies. The risk of recurrent disease following surgical resection is low. Case history. A 70-year-old patient was admitted to the emergency room after falling at home. CT evaluation revealed a pelvic mass and free fluid in the abdomen and pelvis. Her serum CA-125 level was greatly elevated. The patient underwent an abdominal hysterectomy with bilateral salpingo-oophorectomy. Histologic examination revealed serous psammocarcinoma of the ovary. Conclusion. Psammocarcinoma is a rare form of ovarian cancer associated with a favorable prognosis. However, the rare incidence of this disease and inconsistent biological behavior can confound the diagnosis for the treating physician.