Differences in gynecologic tumor development in Amhr2-Cre mice with KRAS G12D or KRAS G12V mutations

How different KRAS variants impact tumor initiation and progression in vivo has not been thoroughly examined. We hypothesize that the ability of either KRAS G12D or KRAS G12V mutations to initiate tumor formation is context dependent. Amhr2-Cre mice express Cre recombinase in tissues that develop into the fallopian tubes, uterus, and ovaries. We used these mice to conditionally express either the KRAS G12V/ + or KRAS G12D/ + mutation. Mice with the genotype Amhr2-Cre Pten (fl/fl) Kras G12D/ + (G12D mice) had abnormal follicle structures and developed low-grade serous ovarian carcinomas with 100% penetrance within 18 weeks. In contrast, mice with the genotype Amhr2-Cre Pten (fl/fl) Kras G12V/ + (G12V mice) had normal follicle structures, and about 90% of them developed uterine tumors with diverse histological features resembling those of leiomyoma and leiomyosarcoma. Granulosa cell tumors also developed in G12V mice. Differences in cell-signaling pathways in the uterine tissues of G12D and G12V mice were identified using RNA sequencing and reverse-phase protein array analyses. We found that CTNNB1, IL1A, IL1B, TNF, TGFB1, APP, and IL6 had the higher activity in G12V mice than in G12D mice. These mouse models will be useful for studying the differences in signaling pathways driven by Kras G12V/ + or Kras G12D/ + mutations to aid development of targeted therapies for specific KRAS mutant variants. Our leiomyoma model driven by the Kras G12V/ + mutation will also be useful in deciphering the malignant progression from leiomyoma to leiomyosarcoma.