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

ABSTRACT

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. 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. 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. 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.