Aim: Endometriosis-related ovarian neoplasms (ERONs) have recently attracted considerable attention; however, the prevalence and patterns of ARID1A and POLE mutations in ERONs have not been studied in detail. The aim of this study was to investigate not only the carcinogenesis of ERONs, but also the prognostic significance of several gene mutations in this cohort. We used DNA purified from only tumor epithelial cells, from which fibroblasts were removed, using a specific method we called "liquid microdissection".
Methods: Tissue samples from 22 ovarian carcinomas (13 endometrioid, and nine clear cell) were used. Tumor cells were isolated using a cell sorting system and DNA was purified from tumor epithelial cells. Nucleotide sequencing was conducted to analyze the mutational status of ARID1A, p53, PTEN, POLE, PIK3CA, and KRAS.
Results: In ERONs, the frequencies of somatic mutations in ARID1A, p53, POLE, PTEN, PIK3CA, and KRAS were 19/20 (95.0%), 7/19 (36.8%), 9/22 (40.9%), 13/19 (68.4%), 3/19 (15.8%), and 1/9 (11.1%). The frequency of ARID1A mutations was significantly higher than that reported previously. Kaplan-Meier survival analysis revealed that mutations in all genes, including POLE, were not associated with patient prognosis in our Japanese cohort.
Conclusions: Our results suggest that the frequency of ARID1A mutations in ERONs may be higher than that previously reported. In addition, the "liquid microdissection" method that we chose for DNA purification could be used to obtain high-quality sequencing results. The findings suggest that ARID1A mutations represent the basis of ERON carcinogenesis; other subsequent gene mutations may result in the progression of carcinogenesis.
Keywords: ARID1A; POLE; liquid microdissection; ovarian clear cell carcinoma; ovarian endometrioid carcinoma.