Mev Dominguez-Valentin

Familial colorectal cancer type X: genetic profiles and phenotypic features

Heredity is a major cause of colorectal cancer, but although several rare high-risk syndromes have been linked to disease-predisposing mutations, the genetic mechanisms are undetermined in the majority of families suspected of hereditary cancer. We review the clinical presentation, histopathologic features, and the genetic and epigenetic profiles of the familial colorectal cancer type X (FCCTX) syndrome with the aim to delineate tumor characteristics that may contribute to refined diagnostics and optimized tumor prevention.

Distinct Gene Expression Signatures in Lynch Syndrome and Familial Colorectal Cancer Type X

Introduction Heredity is estimated to cause at least 20% of colorectal cancer. The hereditary nonpolyposis colorectal cancer subset is divided into Lynch syndrome and familial colorectal cancer type X (FCCTX) based on presence of mismatch repair (MMR) gene defects. Purpose We addressed the gene expression signatures in colorectal cancer linked to Lynch syndrome and FCCTX with the aim to identify candidate genes and to map signaling pathways relevant in hereditary colorectal carcinogenesis. Experimental design The 18 k whole-genome c-DNA-mediated annealing, selection, extension, and ligation (WG-DASL) assay was applied to 123 colorectal cancers, including 39 Lynch syndrome tumors and 37 FCCTX tumors. Target genes were technically validated using real-time quantitative RT-PCR (qRT-PCR) and the expression signature was validated in independent datasets. Results Colorectal cancers linked to Lynch syndrome and FCCTX showed distinct gene expression profiles, which by significance analysis of microarrays (SAM) differed by 2188 genes. Functional pathways involved were related to G-protein coupled receptor signaling, oxidative phosphorylation, and cell cycle function and mitosis. qRT-PCR verified altered expression of the selected genes NDUFA9, AXIN2, MYC, DNA2 and H2AFZ. Application of the 2188-gene signature to independent datasets showed strong correlation to MMR status. Conclusion Distinct genetic profiles and deregulation of different canonical pathways apply to Lynch syndrome and FCCTX and key targets herein may be relevant to pursue for refined diagnostic and therapeutic strategies in hereditary colorectal cancer.

Gain of chromosomal region 20q and loss of 18 discriminates between Lynch syndrome and familial colorectal cancer

Lynch syndrome and familial colorectal cancer type X, FCCTX, represent the two predominant colorectal cancer syndromes. Whereas Lynch syndrome is clinically and genetically well defined, the genetic cause of FCCTX is unknown and genomic differences between Lynch syndrome and FCCTX tumours are largely unknown. We applied array-based comparative genomic hybridisation to 23 colorectal cancers from FCCTX with comparison to 23 Lynch syndrome tumours and to 45 sporadic colorectal cancers. FCCTX tumours showed genomic complexity with frequent gains on chromosomes 20q, 19 and 17 and losses of 18, 8p and 15. Gain of genetic material in two separate regions encompassing, 20q12-13.12 and 20q13.2-13.32, was identified in 65% of the FCCTX tumours. Gain of material on chromosome 20q and loss on chromosome 18 significantly discriminated colorectal cancers associated with FCCTX from Lynch syndrome, which likely signifies different preferred tumourigenic pathways.

Urinary Tract Cancer in Lynch Syndrome; Increased Risk in Carriers of MSH2 Mutations.

OBJECTIVE To evaluate the risk of urothelial cancer in the upper urinary tract and the bladder, determine the contribution from the different mismatch-repair genes, and define clinical characteristics of urothelial cancer in Lynch syndrome. MATERIALS AND METHODS The national hereditary nonpolyposis colorectal cancer registry was used to identify all 288 Lynch syndrome families in Denmark. Urothelial cancers that developed in mutation carriers and in their first-degree relatives were identified, mismatch-repair status was assessed, clinicopathologic variables were defined, and cumulative lifetime risks were determined. RESULTS In total, 48 cancers of the ureter, 34 cancers of the renal pelvis, and 54 urinary bladder cancers developed at a mean age of 61 (24-89) years. The tumors were typically of high grade, showed loss of mismatch-repair protein expression in 90% of the tumors and microsatellite instability in 23% of the tumors. Mutations in MSH2 were overrepresented (73%), and MSH2 mutation carriers were at a significantly increased risk of developing urinary tract cancer compared with individuals with mutations in MLH1 or MSH6. CONCLUSION Cancers of the upper urinary tract and the urinary bladder are included in the Lynch syndrome tumor spectrum. Urothelial cancers are predominantly linked to MSH2 mutations, which suggest that surveillance should be targeted at individuals with mutations herein.

Mutation spectrum in South American Lynch syndrome families

BackgroundGenetic counselling and testing for Lynch syndrome have recently been introduced in several South American countries, though yet not available in the public health care system.MethodsWe compiled data from publications and hereditary cancer registries to characterize the Lynch syndrome mutation spectrum in South America. In total, data from 267 families that fulfilled the Amsterdam criteria and/or the Bethesda guidelines from Argentina, Brazil, Chile, Colombia and Uruguay were included.ResultsDisease-predisposing mutations were identified in 37% of the families and affected MLH1 in 60% and MSH2 in 40%. Half of the mutations have not previously been reported and potential founder effects were identified in Brazil and in Colombia.ConclusionThe South American Lynch syndrome mutation spectrum includes multiple new mutations, identifies potential founder effects and is useful for future development of genetic testing in this continent.

Key roles for MYC, KIT and RET signaling in secondary angiosarcomas.

Background:Angiosarcomas may develop as primary tumours of unknown cause or as secondary tumours, most commonly following radiotherapy to the involved field. The different causative agents may be linked to alternate tumorigenesis, which led us to investigate the genetic profiles of morphologically indistinguishable primary and secondary angiosarcomas.Methods:Whole-genome (18k) c-DNA-mediated annealing, selection, extension and ligation analysis was used to genetically profile 26 primary and 29 secondary angiosarcomas. Key findings were thereafter validated using RT–qPCR, immunohistochemistry and validation of the gene signature to an external data set.Results:In total, 103 genes were significantly deregulated between primary and secondary angiosarcomas. Secondary angiosarcomas showed upregulation of MYC, KIT and RET and downregulation of CDKN2C. Functional annotation analysis identified multiple target genes in the receptor protein tyrosine kinase pathway. The results were validated using RT–qPCR and immunohistochemistry. Further, the gene signature was applied to an external data set and, herein, distinguished primary from secondary angiosarcomas.Conclusions:Upregulation of MYC, KIT and RET and downregulation of CDKN2C characterise secondary angiosarcoma, which implies possibilities for diagnostic application and a mechanistic basis for therapeutic evaluation of RET-kinase-inhibitors in these highly aggressive tumours.

Distinct gene expression profiles in ovarian cancer linked to Lynch syndrome

Ovarian cancer linked to Lynch syndrome represents a rare subset that typically presents at young age as early-stage tumors with an overrepresentation of endometrioid and clear cell histologies. We investigated the molecular profiles of Lynch syndrome-associated and sporadic ovarian cancer with the aim to identify key discriminators and central tumorigenic mechanisms in hereditary ovarian cancer. Global gene expression profiling using whole-genome c-DNA-mediated Annealing, Selection, extension, and Ligation was applied to 48 histopathologically matched Lynch syndrome-associated and sporadic ovarian cancers. Lynch syndrome-associated and sporadic ovarian cancers differed by 349 significantly deregulated genes, including PTPRH, BIRC3, SHH and TNFRSF6B. The genes involved were predominantly linked to cell growth, proliferation, and cell-to-cell signaling and interaction. When stratified for histologic subtype, hierarchical clustering confirmed distinct differences related to heredity in the endometrioid and serous subtypes. Furthermore, separate clustering was achieved in an independent, publically available data set. The distinct genetic signatures in Lynch syndrome-associated and sporadic ovarian cancers point to alternative preferred tumorigenic routes and suggest that genetic discriminators may be relevant for molecular diagnostics and targeted therapeutics.

Molecular Subtyping of Serous Ovarian Tumors Reveals Multiple Connections to Intrinsic Breast Cancer Subtypes

Objective Transcriptional profiling of epithelial ovarian cancer has revealed molecular subtypes correlating to biological and clinical features. We aimed to determine gene expression differences between malignant, benign and borderline serous ovarian tumors, and investigate similarities with the well-established intrinsic molecular subtypes of breast cancer. Methods Global gene expression profiling using Illuminas HT12 Bead Arrays was applied to 59 fresh-frozen serous ovarian malignant, benign and borderline tumors. Nearest centroid classification was performed applying previously published gene profiles for the ovarian and breast cancer subtypes. Correlations to gene expression modules representing key biological breast cancer features were also sought. Validation was performed using an independent, publicly available dataset. Results 5,944 genes were significantly differentially expressed between benign and malignant serous ovarian tumors, with cell cycle processes enriched in the malignant subgroup. Borderline tumors were split between the two clusters. Significant correlations between the malignant serous tumors and the highly aggressive ovarian cancer signatures, and the basal-like breast cancer subtype were found. The benign and borderline serous tumors together were significantly correlated to the normal-like breast cancer subtype and the ovarian cancer signature derived from borderline tumors. The borderline tumors in the study dataset, in addition, also correlated significantly to the luminal A breast cancer subtype. These findings remained when analyzed in an independent dataset, supporting links between the molecular subtypes of ovarian cancer and breast cancer beyond those recently acknowledged. Conclusions These data link the transcriptional profiles of serous ovarian cancer to the intrinsic molecular subtypes of breast cancer, in line with the shared clinical and molecular features between high-grade serous ovarian cancer and basal-like breast cancer, and suggest that biomarkers and targeted therapies may overlap between these tumor subsets. The link between benign and borderline ovarian cancer and luminal breast cancer may indicate endocrine responsiveness in a subset of ovarian cancers.

Functional implications of the p.Cys680Arg mutation in the MLH1 mismatch repair protein

In clinical genetic diagnostics, it is difficult to predict whether genetic mutations that do not greatly alter the primary sequence of the encoded protein causing unknown functional effects on cognate proteins lead to development of disease. Here, we report the clinical identification of c.2038 T>C missense mutation in exon 18 of the human MLH1 gene and biochemically characterization of the p.Cys680Arg mutant MLH1 protein to implicate it in the pathogenicity of the Lynch syndrome (LS). We show that the mutation is deficient in DNA mismatch repair and, therefore, contributing to LS in the carriers.

Abstract B8: Molecular subtyping of epithelial ovarian cancer reveals connections to intrinsic breast cancer subtypes

Aim: Epithelial ovarian cancer is one of the most lethal female cancers. It is a heterogeneous group of neoplasms and the different histologic subtypes are thought to constitute separate disease entities. Efforts have been made to characterize ovarian cancers further and molecular subgroups that correlate to clinical features have been reported, but are still not in clinical use (Tothill et al., Clin Cancer Res , 2008). The subgroups, called C1-C6, represent serous and endometrioid ovarian tumors with the C1-C2 and C4-C5 subgroups characterizing high-grade serous tumors and correlated to a worse prognosis. The C3 and C6 subtypes represent borderline and low-grade tumors and show a favorable prognosis. We aimed to further outline and refine the genetic differences between malignant, benign and borderline ovarian tumors and to investigate similarities between ovarian cancer and the well described intrinsic subtypes of breast cancer (Perou et al., Nature , 2000). Materials and methods: Global gene expression profiling (Illumina HT-12 bead arrays) was applied to 72 fresh-frozen serous ovarian tumors (37 adenocarcinomas, 17 adenomas, 5 borderline tumors,13 biological replicates) collected in the ovarian tumor tissue biobank at Skane University Hospital, Sweden (2004-2011). We performed nearest centroid classification of our tumors for the molecular subtypes of ovarian cancer (“C-signatures”) as well as for the intrinsic subgroups of breast cancer (luminal A, luminal B, basal-like, normal-like, and HER2) using the genes from Hu et al. ( BMC Genomics , 2006). The results were validated by performing nearest centroid classification of the intrinsic breast cancer subtypes and the C-signatures on the ovarian tumors in the Tothill cohort as well. Results: Our malignant tumors correlated significantly to the basal-like breast cancer subtype (p<0.001) and to the ovarian C1, C2 and C4 signatures (p=0.020). The basal-like tumors, in turn, correlated significantly to the C2 and C4 signatures (p=0.019 and p=0.001, respectively), thus supporting a link between molecular subtypes of ovarian and breast cancers. The borderline and benign tumors showed a significant correlation to the normal-like breast cancer subtype and the ovarian C3 signature, and these signatures also correlated significantly with each other (p<0.001). These findings were supported when the breast cancer subtypes were applied to the Tothill cohort; the basal-like subtype correlated significantly to the C2 signature and the normal-like subtype to the C3 signature (p<0.001). Of interest, there was a tendency towards worse prognosis among malignant tumors that correlated to the basal-like breast cancer subtype compared to the other malignant tumors, which is in line with similar findings in breast cancer. All reported p-values are calculated using Fischers Exact Test. Conclusion: Both epithelial ovarian cancers and breast cancers are heterogeneous diseases, nevertheless they share many similarities such as hormonal influence and varying long-term prognosis. Our novel findings support a link between previously reported molecular subtypes in ovarian cancer and the well-established intrinsic subtypes of breast cancer, which could potentially be of use for further investigations of biomarkers in ovarian cancer and new thinking regarding the use of chemotherapeutic agents as well as targeted treatments. Citation Format: Jenny-Maria Jonsson, Mev Dominguez-Valentin, Ida Johansson, Siker Kimbung, Mats Jonsson, Anna Masback, Susanne Malander, Mef Nilbert. Molecular subtyping of epithelial ovarian cancer reveals connections to intrinsic breast cancer subtypes. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B8.