ABSTRACT
BACKGROUND: MAP2K4 is a putative tumor and metastasis suppressor gene frequently found to be deleted in various cancer types. We aimed to conduct a comprehensive analysis of this gene to assess its involvement in ovarian cancer. METHODS: We screened for mutations in MAP2K4 using High Resolution Melt analysis of 149 primary ovarian tumors and methylation at the promoter using Methylation-Specific Single-Stranded Conformation Polymorphism analysis of 39 tumors. We also considered the clinical impact of changes in MAP2K4 using publicly available expression and copy number array data. Finally, we used siRNA to measure the effect of reducing MAP2K4 expression in cell lines. RESULTS: In addition to 4 previously detected homozygous deletions, we identified a homozygous 16 bp truncating deletion and a heterozygous 4 bp deletion, each in one ovarian tumor. No promoter methylation was detected. The frequency of MAP2K4 homozygous inactivation was 5.6% overall, and 9.8% in high-grade serous cases. Hemizygous deletion of MAP2K4 was observed in 38% of samples. There were significant correlations of copy number and expression in three microarray data sets. There was a significant correlation between MAP2K4 expression and overall survival in one expression array data set, but this was not confirmed in an independent set. Treatment of JAM and HOSE6.3 cell lines with MAP2K4 siRNA showed some reduction in proliferation. CONCLUSIONS: MAP2K4 is targeted by genetic inactivation in ovarian cancer and restricted to high grade serous and endometrioid carcinomas in our cohort.
Subject(s)
MAP Kinase Kinase 4/genetics , Ovarian Neoplasms/enzymology , Ovarian Neoplasms/genetics , Tumor Suppressor Proteins/genetics , Adult , Aged , Aged, 80 and over , Base Sequence , Cell Proliferation , DNA Methylation/genetics , Female , Gene Dosage/genetics , Gene Expression Regulation, Neoplastic/genetics , Gene Knockdown Techniques , Genotype , Humans , Middle Aged , Molecular Sequence Data , Mutation/genetics , Ovarian Neoplasms/mortality , Promoter Regions, Genetic/genetics , Survival AnalysisABSTRACT
Identification of genomic alterations defining ovarian carcinoma subtypes may aid the stratification of patients to receive targeted therapies. We characterized high-grade serous ovarian carcinoma (HGSC) for the association of amplified and overexpressed genes with clinical outcome using gene expression data from 499 HGSC patients in the Ovarian Tumor Tissue Analysis cohort for 11 copy number amplified genes: ATP13A4, BMP8B, CACNA1C, CCNE1, DYRK1B, GAB2, PAK4, RAD21, TPX2, ZFP36, and URI. The Australian Ovarian Cancer Study and The Cancer Genome Atlas datasets were also used to assess the correlation between gene expression, patient survival, and tumor classification. In a multivariate analysis, high GAB2 expression was associated with improved overall and progression-free survival (P = 0.03 and 0.02), whereas high BMP8B and ATP13A4 were associated with improved progression-free survival (P = 0.004 and P = 0.02). GAB2 overexpression and copy number gain were enriched in the AOCS C4 subgroup. High GAB2 expression correlated with enhanced sensitivity in vitro to the dual PI3K/mTOR inhibitor PF-04691502 and could be used as a genomic marker for identifying patients who will respond to treatments inhibiting PI3K signaling.
Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Cystadenocarcinoma, Serous/genetics , Gene Expression Regulation, Neoplastic , Ovarian Neoplasms/genetics , Phosphoinositide-3 Kinase Inhibitors , Pyridones/pharmacology , Pyrimidines/pharmacology , Adaptor Proteins, Signal Transducing/metabolism , Adult , Aged , Aged, 80 and over , Cell Line, Tumor , Cell Survival/drug effects , Cell Survival/genetics , Cystadenocarcinoma, Serous/metabolism , Cystadenocarcinoma, Serous/therapy , DNA Copy Number Variations , Disease-Free Survival , Female , Gene Amplification , Gene Expression Profiling , Gene Regulatory Networks , Humans , Kaplan-Meier Estimate , Middle Aged , Multivariate Analysis , Neoplasm Grading , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/therapy , Young AdultABSTRACT
PURPOSE: Ovarian cancer has the highest mortality rate of all the gynecologic malignancies and is responsible for approximately 140,000 deaths annually worldwide. Copy number amplification is frequently associated with the activation of oncogenic drivers in this tumor type, but their cytogenetic complexity and heterogeneity has made it difficult to determine which gene(s) within an amplicon represent(s) the genuine oncogenic driver. We sought to identify amplicon targets by conducting a comprehensive functional analysis of genes located in the regions of amplification in high-grade serous and endometrioid ovarian tumors. EXPERIMENTAL DESIGN: High-throughput siRNA screening technology was used to systematically assess all genes within regions commonly amplified in high-grade serous and endometrioid cancer. We describe the results from a boutique siRNA screen of 272 genes in a panel of 18 ovarian cell lines. Hits identified by the functional viability screen were further interrogated in primary tumor cohorts to determine the clinical outcomes associated with amplification and gene overexpression. RESULTS: We identified a number of genes as critical for cellular viability when amplified, including URI1, PAK4, GAB2, and DYRK1B. Integration of primary tumor gene expression and outcome data provided further evidence for the therapeutic use of such genes, particularly URI1 and GAB2, which were significantly associated with survival in 2 independent tumor cohorts. CONCLUSION: By taking this integrative approach to target discovery, we have streamlined the translation of high-resolution genomic data into preclinical in vitro studies, resulting in the identification of a number of genes that may be specifically targeted for the treatment of advanced ovarian tumors.