Frequent PIK3CA mutations in eutopic endometrium of patients with ovarian clear cell carcinoma

Kosuke Murakami, Akiko Kanto, Kazuko Sakai, Chiho Miyagawa, Hisamitsu Takaya, Hidekatsu Nakai, Yasushi Kotani, Kazuto Nishio, Noriomi Matsumura
In: bioRxiv · 2021 · doi:10.1101/2021.02.25.432943 · W3130949224
preprint OA: green CC0
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⚙ AI-generated summary by claude@2026-06, 2026-06-09 ⓘ

Frequent *PIK3CA* hotspot mutations were found in eutopic endometrial glands of ovarian cancer and endometriosis patients, often appearing as multiple mutations within single glands and suggesting passenger rather than driver roles.

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Abstract

Abstract Recent studies have reported cancer-associated mutations in normal endometrium. Mutations in eutopic endometrium may lead to endometriosis and endometriosis-associated ovarian cancer. We investigated PIK3CA mutations ( PIK3CA m) for three hotspots (E542K, E545K, H1047R) in eutopic endometrium in patients with ovarian cancer and endometriosis from formalin-fixed paraffin-embedded specimens by laser-capture microdissection and droplet digital PCR. The presence of PIK3CA m in eutopic endometrial glands with mutant allele frequency ≥15% were as follows: ovarian clear cell carcinoma (OCCC) with PIK3CA m in tumors, 20/300 hotspots in 11/14 cases; OCCC without PIK3CA m, 42/78 hotspots in 11/12 cases; high-grade serous ovarian carcinoma, 8/45 hotspots in 3/5 cases; and endometriotic cysts, 5/63 hotspots in 5/6 cases. These rates were more frequent than in non-cancer non-endometriosis controls (7/309 hotspots in 5/17 cases). In OCCC without PIK3CA m, 7/12 (58%) cases showed multiple hotspot mutations in the same eutopic endometrial glands. In 3/54 (5.6%) cases, PIK3CA m was found in eutopic endometrial stroma. Multi-sampling of the OCCC tumors with PIK3CA m showed intratumor heterogeneity in three of eight cases. In two cases, PIK3CA m was detected in the stromal component of the tumor. Homogenous PIK3CA m in the epithelial component of the tumor matched the mutation in eutopic endometrial glands in only one case. Eutopic endometrial glands in ovarian cancer and endometriosis show high frequency of PIK3CA m that is not consistent with tumors, and multiple hotspot mutations are often found in the same glands. Our results suggest that most PIK3CA m in eutopic endometrial glands are passenger rather than driver mutations.

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Condition tags

endometriosis

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References (77)

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