Genomic characterization of Chinese ovarian clear cell carcinoma identifies driver genes by whole exome sequencing

Background: Little is known about the genetic alterations characteristic of ovarian clear cell carcinoma (OCCC). Our aim was to identify targetable genomic alterations in this type of cancer. Methods: Forty-two OCCC formalin-fixed, paraffin-embedded (FFPE) tissue samples were analyzed by whole-exome sequencing (WES), and 74 FFPE tissue samples underwent targeted sequencing (TS) to confirm the relevant driver mutations. Cell proliferation was assessed by cell counting kit-8 (CCK8) assays. Findings: In the 42 samples, ARID1A (64.3%) and PIK3CA (28.5%) were frequently mutated, as were PPP2R1A (11.9%), PTEN (7.1%) and KRAS (4.8%), which have been reported in previous OCCC studies. We also detected mutations in MUC4 (28.6%), MAGEE1 (19%), and ARID3A (16.7%); associations with these genes have not been previously reported. The functional protein-activated pathways were associated with proliferation and survival (including the PI3K/AKT, TP53, and ERBB2 pathways) in 83% of OCCCs and with chromatin remodeling in 71% of OCCCs. Patients with alterations in MAGEE1 (64% in the targeted sequencing cohort) had worse clinical outcomes (log-rank p < 0.05). A functional study revealed that two MAGEE1 mutants, one lacking two MAGE domains and the other containing two MAGE domains, significantly decreased the proliferative capacity of OCCC cells. Funding: We successfully identified novel genetic alterations in OCCC using whole-exome sequencing and targeted sequencing of OCCC patient samples and potential therapeutic targets for the treatment of this malignancy. Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: The use of samples and medical records was approved by the research ethics committees of Shanghai University of Medicine & Health Sciences Affiliated with Sixth People’s Hospital South Campus (approval number: 2017-KY-01), Fujian Provincial Maternity and Children's Hospital (approval number: 2017049), Nanjing Medical University Affiliated with Changzhou Maternal and Child Health Care Hospital (approval number: 2017005), Nanjing Medical University Affiliated with Changzhou No. 2 People’s Hospital (approval number: 2016-017-01), and Nanjing Medical University Affiliated with Suzhou Municipal Hospital (approval number: L2017003).