scholarly journals A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Caitlin T. Fierheller ◽  
Laure Guitton-Sert ◽  
Wejdan M. Alenezi ◽  
Timothée Revil ◽  
Kathleen K. Oros ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Repair ◽  
Cell Lines ◽  
Carrier Frequency ◽  
Pathogenic Variant ◽  
Fanconi Anaemia ◽  
Repair Pathway ◽  
French Canadian ◽  
Pathogenic Variants ◽  
Gene And Protein Expression

Abstract Background Familial ovarian cancer (OC) cases not harbouring pathogenic variants in either of the BRCA1 and BRCA2 OC-predisposing genes, which function in homologous recombination (HR) of DNA, could involve pathogenic variants in other DNA repair pathway genes. Methods Whole exome sequencing was used to identify rare variants in HR genes in a BRCA1 and BRCA2 pathogenic variant negative OC family of French Canadian (FC) ancestry, a population exhibiting genetic drift. OC cases and cancer-free individuals from FC and non-FC populations were investigated for carrier frequency of FANCI c.1813C>T; p.L605F, the top-ranking candidate. Gene and protein expression were investigated in cancer cell lines and tissue microarrays, respectively. Results In FC subjects, c.1813C>T was more common in familial (7.1%, 3/42) than sporadic (1.6%, 7/439) OC cases (P = 0.048). Carriers were detected in 2.5% (74/2950) of cancer-free females though female/male carriers were more likely to have a first-degree relative with OC (121/5249, 2.3%; Spearman correlation = 0.037; P = 0.011), suggesting a role in risk. Many of the cancer-free females had host factors known to reduce risk to OC which could influence cancer risk in this population. There was an increased carrier frequency of FANCI c.1813C>T in BRCA1 and BRCA2 pathogenic variant negative OC families, when including the discovery family, compared to cancer-free females (3/23, 13%; OR = 5.8; 95%CI = 1.7–19; P = 0.005). In non-FC subjects, 10 candidate FANCI variants were identified in 4.1% (21/516) of Australian OC cases negative for pathogenic variants in BRCA1 and BRCA2, including 10 carriers of FANCI c.1813C>T. Candidate variants were significantly more common in familial OC than in sporadic OC (P = 0.04). Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the Fanconi anaemia (FA) pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level, destabilized by DNA damaging agent treatment in both HeLa and OC cell lines, and exhibited sensitivity to cisplatin but not to a poly (ADP-ribose) polymerase inhibitor. By tissue microarray analyses, FANCI protein was consistently expressed in fallopian tube epithelial cells and only expressed at low-to-moderate levels in 88% (83/94) of OC samples. Conclusions This is the first study to describe candidate OC variants in FANCI, a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that pathogenic FANCI variants may modify OC risk in cancer families.

scholarly journals The genetic analysis of a founder Northern American population of European descent identifies FANCI as a candidate familial ovarian cancer risk gene

2020 ◽  
Author(s):  
Caitlin T Fierheller ◽  
Laure Guitton-Sert ◽  
Wejdan M Alenezi ◽  
Timothée Revil ◽  
Kathleen K Oros ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Repair ◽  
Family History ◽  
Serous Carcinoma ◽  
Ovarian Cancer Risk ◽  
Repair Pathway ◽  
Degree Relative ◽  
Pathogenic Variants ◽  
Familial Ovarian Cancer ◽  
History Of

AbstractSome familial ovarian cancer (OC) could be due to rare risk alleles in genes that each account for a relatively small proportion of cases not due to BRCA1 and BRCA2, major risk genes in the homologous recombination (HR) DNA repair pathway. We report a new candidate OC risk allele, FANCI c.1813C>T in a Fanconi anemia (FA) gene that plays a role upstream of the HR DNA repair pathway. This variant was identified by whole exome sequencing of a BRCA1 and BRCA2 mutation-negative French Canadian (FC) OC family from a population exhibiting founder effects. In FCs, the c.1813C>T allele was detected in 7% (3/43) of familial and 1.6% (7/439) of sporadic OC cases; and in 3.7% (3/82) of familial breast cancer (BC) cases with a family history of OC and in 1.9% (3/158) of BC only families. This allele was significantly associated with FC BRCA1 and BRCA2 mutation-negative OC families (OR=5.6; 95%CI=1.6-19; p=0.006). Although FANCI c.1813C>T was detected in 2.5% (74/2950) of cancer-free FC females, carriers had a personal history of known OC risk reducing factors, and female/male carriers were more likely to have reported a first-degree relative with OC (ρ=0.037; p=0.011). Eight rare potentially pathogenic FANCI variants were identified in 3.3% (17/516) of Australian OC cases, including 10 carriers of FANCI c.1813C>T. Potentially pathogenic FANCI variants were significantly more common in AUS OC cases with a family history of OC than in isolated OC cases (p=0.027). The odds ratios (OR) were >3 for carriers of any of the seven rarest FANCI alleles, and 1.5 for c.1813C>T. Data from the OC Association Consortium revealed that the ORs for the c.1813C>T allele were highest for the most common OC subtypes. Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the FA pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level; unstable by formaldehyde or mitomycin C treatment; and exhibited sensitivity to cisplatin but not to olaparib (a poly [ADP-ribose] polymerase inhibitor). By tissue microarray analyses, FANCI protein was robustly expressed in fallopian tube epithelial cells but expressed at low-to-moderate levels in 88% (83/94) of high-grade serous carcinoma OC samples. This is the first study to describe potentially pathogenic variants in OC in a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that potentially pathogenic FANCI variants may modify OC risk in cancer families.

scholarly journals 900 Depleting non-canonical, cell-intrinsic PD-L1 signals induces synthetic lethality to small molecule DNA damage response inhibitors in an immune independent and dependent manner

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A944-A944
Author(s):  
Anand Kornepati ◽  
Clare Murray ◽  
Barbara Avalos ◽  
Cody Rogers ◽  
Kavya Ramkumar ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Lines ◽  
Dna Damage Response ◽  
Small Molecule ◽  
Treatment Resistance ◽  
Programmed Death ◽  
Damage Response ◽  
Response Biomarker

BackgroundTumor surface-expressed programmed death-ligand 1 (PD-L1) suppresses immunity when it engages programmed death-1 (PD-1) on anti-tumor immune cells in canonical PD-L1/PD-1.1 Non-canonical, tumour-intrinsic PD-L1 signals can mediate treatment resistance2–6 but mechanisms remain incompletely understood. Targeting non-canonical, cell-intrinsic PD-L1 signals, especially modulation of the DNA damage response (DDR), remains largely untapped.MethodsWe made PD-L1 knockout (PD-L1 KO) murine transplantable and human cell lines representing melanoma, bladder, and breast histologies. We used biochemical, genetic, and cell-biology techniques for mechanistic insights into tumor-intrinsic PD-L1 control of specific DDR and DNA repair pathways. We generated a novel inducible melanoma GEMM lacking PD-L1 only in melanocytes to corroborate DDR alterations observed in PD-L1 KO of established tumors.ResultsGenetic tumor PD-L1 depletion destabilized Chk2 and impaired ATM/Chk2, but not ATR/Chk1 DDR. PD-L1KO increased DNA damage (γH2AX) and impaired homologous recombination DNA repair (p-RPA32, BRCA1, RAD51 nuclear foci) and function (DR-GFP reporter). PD-L1 KO cells were significantly more sensitive versus controls to DDR inhibitors (DDRi) against ATR, Chk1, and PARP but not ATM in multiple human and mouse tumor models in vitro and in vivo in NSG mice. PD-1 independent, intracellular, not surface PD-L1 stabilized Chk2 protein with minimal Chek2 mRNA effect. Mechanistically, PD-L1 could directly complex with Chk2, protecting it from PIRH2-mediated polyubiquitination. PD-L1 N-terminal domains Ig-V and Ig-C but not the PD-L1 C-terminal tail co-IP’d with Chk2 and restored Chk1 inhibitor (Chk1i) treatment resistance. Tumor PD-L1 expression correlated with Chk1i sensitivity in 44 primary human small cell lung cancer cell lines, implicating tumor-intrinsic PD-L1 as a DDRi response biomarker. In WT mice, genetic PD-L1 depletion but not surface PD-L1 blockade with αPD-L1, sensitized immunotherapy-resistant, BRCA1-WT 4T1 tumors to PARP inhibitor (PARPi). PARPi effects were reduced on PD-L1 KO tumors in RAG2KO mice indicating immune-dependent DDRi efficacy. Tumor PD-L1 depletion, likely due to impaired DDR, enhanced PARPi induced tumor-intrinsic STING activation (e.g., p-TBK1, CCL5) suggesting potential to augment immunotherapies.ConclusionsWe challenge the prevailing surface PD-L1 paradigm and establish a novel mechanism for cell-intrinsic PD-L1 control of the DDR and gene product expression. We identify therapeutic vulnerabilities from tumor PD-L1 depletion utilizing small molecule DDRi currently being tested in clinical trials. Data could explain αPD-L1/DDRi treatment resistance. Intracellular PD-L1 could be a pharmacologically targetable treatment target and/or response biomarker for selective DDRi alone plus other immunotherapies.ReferencesTopalian SL, Taube JM, Anders RA, Pardoll DM. Mechanism-driven biomarkers to guide immune checkpoint blockade in cancer therapy. Nat Rev Cancer 16:275–287, doi:10.1038/nrc.2016.36 (2016).Clark CA, et al. Tumor-intrinsic PD-L1 signals regulate cell growth, pathogenesis and autophagy in ovarian cancer and melanoma. Canres 0258.2016 (2016).Gupta HB et al. Tumor cell-intrinsic PD-L1 promotes tumor-initiating cell generation and functions in melanoma and ovarian cancer. 1, 16030 (2016).Zhu H, et al. BET bromodomain inhibition promotes anti-tumor immunity by suppressing PD-L1 expression. Cell Rep 16:2829–2837, doi:10.1016/j.celrep.2016.08.032 (2016)Wu B, et al. Adipose PD-L1 modulates PD-1/PD-L1 checkpoint blockade immunotherapy efficacy in breast cancer. Oncoimmunology 7:e1500107, doi:10.1080/2162402X.2018.1500107 (2018)Liang J, et al. Verteporfin inhibits PD-L1 through autophagy and the STAT1-IRF1-TRIM28 signaling axis, exerting antitumor efficacy. Cancer Immunol Res 8:952–965, doi:10.1158/2326-6066.CIR-19-0159 (2020)

scholarly journals Can the Synergic Contribution of Multigenic Variants Explain the Clinical and Cellular Phenotypes of a Neurodevelopmental Disorder?

Genes ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 78
Author(s):  
Nuno Maia ◽  
Maria João Nabais Sá ◽  
Cláudia Oliveira ◽  
Flávia Santos ◽  
Célia Azevedo Soares ◽  
...  
Keyword(s):  
Dna Repair ◽  
De Novo ◽  
Biochemical Study ◽  
Neurodevelopmental Disorder ◽  
Chromosome Instability ◽  
Pathogenic Variant ◽  
Fanconi Anaemia ◽  
Cellular Phenotype ◽  
Full Spectrum ◽  
New Genotype

We describe an infant female with a syndromic neurodevelopmental clinical phenotype and increased chromosome instability as cellular phenotype. Genotype characterization revealed heterozygous variants in genes directly or indirectly linked to DNA repair: a de novo X-linked HDAC8 pathogenic variant, a paternally inherited FANCG pathogenic variant and a maternally inherited BRCA2 variant of uncertain significance. The full spectrum of the phenotype cannot be explained by any of the heterozygous variants on their own; thus, a synergic contribution is proposed. Complementation studies showed that the FANCG gene from the Fanconi Anaemia/BRCA (FA/BRCA) DNA repair pathway was impaired, indicating that the variant in FANCG contributes to the cellular phenotype. The patient’s chromosome instability represents the first report where heterozygous variant(s) in the FA/BRCA pathway are implicated in the cellular phenotype. We propose that a multigenic contribution of heterozygous variants in HDAC8 and the FA/BRCA pathway might have a role in the phenotype of this neurodevelopmental disorder. The importance of these findings may have repercussion in the clinical management of other cases with a similar synergic contribution of heterozygous variants, allowing the establishment of new genotype–phenotype correlations and motivating the biochemical study of the underlying mechanisms.

scholarly journals DNA-repair pathway inhibitors for the treatment of ovarian cancer

2010 ◽  
Author(s):  
Igor Martinek ◽  
Krishnayan Haldar ◽  
Kezia Gaitskell ◽  
Andrew Bryant ◽  
Shibani Nicum ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Repair ◽  
Repair Pathway

scholarly journals Pathogenic Variant Profile of Hereditary Cancer Syndromes in a Vietnamese Cohort

2022 ◽  
Vol 11 ◽  
Author(s):  
Van Thuan Tran ◽  
Sao Trung Nguyen ◽  
Xuan Dung Pham ◽  
Thanh Hai Phan ◽  
Van Chu Nguyen ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Genetic Testing ◽  
Hereditary Cancer ◽  
Carrier Frequency ◽  
Hereditary Cancer Syndromes ◽  
Cancer Syndrome ◽  
Pathogenic Variants ◽  
History Of ◽  
Cancer Syndromes ◽  
History Of Cancer

BackgroundHereditary cancer syndromes (HCS) are responsible for 5-10% of cancer cases. Genetic testing to identify pathogenic variants associated with cancer predisposition has not been routinely available in Vietnam. Consequently, the prevalence and genetic landscape of HCS remain unknown.Methods1165 Vietnamese individuals enrolled in genetic testing at our laboratory in 2020. We performed analysis of germline mutations in 17 high- and moderate- penetrance genes associated with HCS by next generation sequencing.ResultsA total of 41 pathogenic variants in 11 genes were detected in 3.2% individuals. The carrier frequency was 4.2% in people with family or personal history of cancer and 2.6% in those without history. The percentage of mutation carriers for hereditary colorectal cancer syndromes was 1.3% and for hereditary breast and ovarian cancer syndrome was 1.6%. BRCA1 and BRCA2 mutations were the most prevalent with the positive rate of 1.3% in the general cohort and 5.1% in breast or ovarian cancer patients. Most of BRCA1 mutations located at the BRCA C-terminus domains and the top recurrent mutation was NM_007294.3:c.5251C>T (p.Arg1751Ter). One novel variant NM_000038.6(APC):c.6665C>A (p.Pro2222His) was found in a breast cancer patient with a strong family history of cancer. A case study of hereditary cancer syndrome was illustrated to highlight the importance of genetic testing.ConclusionThis is the first largest analysis of carrier frequency and mutation spectrum of HCS in Vietnam. The findings demonstrate the clinical significance of multigene panel testing to identify carriers and their at-risk relatives for better cancer surveillance and management strategies.

scholarly journals PARP Inhibitors in Ovarian Cancer: The Route to “Ithaca”

Diagnostics ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 55 ◽  
Author(s):  
Boussios ◽  
Karathanasi ◽  
Cooke ◽  
Neille ◽  
Sadauskaite ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Brca Mutation ◽  
Parp Inhibitor ◽  
Parp Inhibitors ◽  
Parp Inhibition ◽  
Current Evidence ◽  
Repair Pathway ◽  
Significant Efficacy

Poly (ADP-ribose) polymerase (PARP) inhibitors are a novel class of therapeutic agents that target tumors with deficiencies in the homologous recombination DNA repair pathway. Genomic instability characterizes high-grade serous ovarian cancer (HGSOC), with one half of all tumors displaying defects in the important DNA repair pathway of homologous recombination. Early studies have shown significant efficacy for PARP inhibitors in patients with germline breast related cancer antigens 1 and 2 (BRCA1/2) mutations. It has also become evident that BRCA wild-type patients with other defects in the homologous recombination repair pathway benefit from this treatment. Companion homologous recombination deficiency (HRD) scores are being developed to guide the selection of patients that are most likely to benefit from PARP inhibition. The choice of which PARP inhibitor is mainly based upon the number of prior therapies and the presence of a BRCA mutation or HRD. The identification of patients most likely to benefit from PARP inhibitor therapy in view of HRD and other biomarker assessments is still challenging. The aim of this review is to describe the current evidence for PARP inhibitors in ovarian cancer, their mechanism of action, and the outstanding issues, including the rate of long-term toxicities and the evolution of resistance.

Selected Resistance to Topoisomerase II Inhibitors Correlates with the Over Expression of FANCF In a Fanconi Anemia/BRCA DNA Repair Pathway Independent Manner.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3372-3372
Author(s):  
Kenneth H. Shain ◽  
Liang Nong ◽  
Danielle Yarde ◽  
Vasco Oliveira ◽  
William S. Dalton
Keyword(s):  
Dna Repair ◽  
Mrna Expression ◽  
Cell Lines ◽  
Fanconi Anemia ◽  
Repair Pathway ◽  
Core Complex ◽  
Doxorubicin Resistance ◽  
Over Expression ◽  
The Core ◽  
Enhanced Expression

Abstract Abstract 3372 Enhanced expression of the Fanconi Anemia (FA)/BRCA DNA repair pathway correlates with melphalan-resistance in multiple myeloma (MM) cell lines. Continued investigation demonstrated a bortezomib sensitive RelB/p50-mediated regulation of the FA/BRCA pathway contributed to the observed melphalan resistance.(Yarde et al 2009) The FA/BRCA pathway represents a co-dependent DNA damage response pathway involving thirteen loss of function complementation groups cloned from FA patients. The key functional event of this pathway is the interdependent mono-ubiquitination (Ub) of FANCD2 and FANCI (ID complex) by the E3 Ub-ligase activity of the FA core complex a multimer consisting of 8 FA (FANCA, B, C, E, F, G, L and M) and three non-FA proteins (FAAP100, FAAP24 and HES1). Formation of the core complex and mono-Ub of the ID complex appears to revolve around the flexible adapter protein FANCF. Nuclear localization of the core complex components requires binding of FANCA/G and FANCC/E subcomplexes to the C- terminal domain (CTD) and NTD domains of FANCF, respectively. This complex associates with FANCM:FAAP24 at sites of interstand crosslinks (ICL) via the FANCM-binding domain of FANCF, culminating in ID complex mono-Ub, recruitment of BRCA1, BRCA2/FANCD1, FANCJ and FANCN, and homologous recombination (HR) repair. Reduced function of this pathway has been associated with increased genomic instability, cancer susceptibility, and increased sensitivity to DNA cross-linking agents in FA. However, as predicted by the role of the FA/BRCA pathway in DNA repair, enhanced expression of the FA/BRCA pathway has been shown to play an important role in resistance to agents requiring HR for ICL repair. We next examined expression of this pathway in models of resistance to DNA damaging agents not predicted to utilize FA/BRCA activity. We screened 8226/Dox40 doxorubicin resistant and 8226/MR20 mitoxantrone resistant MM cell lines for expression of the 12 FA/BRCA pathway members with quantitative PCR (qPCR) using customized micro-fluidic cards. Interestingly, in these models of topoisomerase (topo) II inhibitor resistance qPCR demonstrated a 2.6 (p<0.05) and 1.7 (p<0.05) fold over expression of FANCF mRNA relative to drug sensitive RPMI8226 cells. Importantly, mRNA expression of other the eleven FA/BRCA pathway constituents was not increased relative to sensitive cells. To further characterize the relationship between FANCF and doxorubicin resistance, we examined mRNA and protein expression of FANCF in RMPI8226, 8226/Dox6 and 8226/Dox40 MM cell lines (representing progressive levels of doxorubicin resistance). FANCF qPCR demonstrated a 2 and 4.7 fold increased in mRNA expression in the 8226/Dox6 and 8226/Dox40 cell lines, respectively (p= 0.103 and p= 0.034) suggesting that increasing expression of FANCF correlated with increasing dox resistance. A similar doxorubicin resistance- dependent increase in FANCF protein was demonstrated by Western blot analysis of these cell lines. Consistent with mRNA results, FANCD2 or FANCG protein levels remained unchanged in the doxorubicin resistant versus sensitive cell lines These observations suggest that FANCF may contribute to topoII inhibitor-mediated DNA double strand break repair, a process that primarily thought to involve non-homologous end joining (NHEJ) independent of the FA/BRCA pathway. To determine if FANCF expression alone could facilitate doxorubicin resistance, pQCXIP-control or pQCXIP-FANCF constructs were expressed in RPMI8226 sensitive MM cells. MTT assays demonstrated a greater than 2 fold resistance to doxorubicin in FANCF over expressing cells at 48 and 96 hours (IC50: 1.33 ×10−6 and 5.3×10−9M) as compared to control cells (3.26×10−6 and 1.13×10−8M). Taken together, these results indicate that the flexible adaptor protein FANCF may participate in doxorubicin resistance independently of other FA/BRCA members. However, future studies will be needed to elucidate the nature of FANCF in doxorubicin resistance. Disclosures: No relevant conflicts of interest to declare.

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