Multiple ovulations, ovarian epithelial inclusion cysts, and it'Smad two!

Protective Effect of Progesterone during Pregnancy against Ovarian Cancer

There have been several epidemiologic studies supporting the protective role of pregnancy, although the mechanism is not clear. High level of progesterone, which is crucial in maintaining pregnancy, has been supposed to be one of the causative factors. Progesterone is produced at the corpus luteum in the early pregnancy and the placenta in the late pregnancy period. In several experimental studies, progesterone was reported to induce apoptosis of ovarian cancer cells through intrinsic and extrinsic pathways. In addition, progesterone has been shown to exert its anticancer effect through genomic and non-genomic action. The objective of this review is to discuss the protective mechanism of pregnancy against ovarian cancer focusing on the steroid hormone, progesterone.

Conditional inactivation of p53 in mouse ovarian surface epithelium does not alter MIS driven Smad2-dominant negative epithelium-lined inclusion cysts or teratomas

Epithelial ovarian cancer is the most lethal gynecological malignancy among US women. The etiology of this disease, although poorly understood, may involve the ovarian surface epithelium or the epithelium of the fallopian tube fimbriae as the progenitor cell. Disruptions in the transforming growth factor beta (TGFβ) pathway and p53 are frequently found in chemotherapy-resistant serous ovarian tumors. Transgenic mice expressing a dominant negative form of Smad2 (Smad2DN), a downstream transcription factor of the TGFβ signaling pathway, targeted to tissues of the reproductive tract were created on a FVB background. These mice developed epithelium-lined inclusion cysts, a potential precursor lesion to ovarian cancer, which morphologically resembled oviductal epithelium but exhibited protein expression more closely resembling the ovarian surface epithelium. An additional genetic “hit” of p53 deletion was predicted to result in ovarian tumors. Tissue specific deletion of p53 in the ovaries and oviducts alone was attempted through intrabursal or intraoviductal injection of Cre-recombinase expressing adenovirus (AdCreGFP) into p53^flox/flox mice. Ovarian bursal cysts were detected in some mice 6 months after intrabursal injection. No pathological abnormalities were detected in mice with intraoviductal injections, which may be related to decreased infectivity of the oviductal epithelium with adenovirus as compared to the ovarian surface epithelium. Bitransgenic mice, expressing both the Smad2DN transgene and p53^flox/flox, were then exposed to AdCreGFP in the bursa and oviductal lumen. These mice did not develop any additional phenotypes. Exposure to AdCreGFP is not an effective methodology for conditional deletion of floxed genes in oviductal epithelium and tissue specific promoters should be employed in future mouse models of the disease. In addition, a novel phenotype was observed in mice with high expression of the Smad2DN transgene as validated through qPCR analysis, characterized by teratoma-like lesions implicating Smad signaling in teratoma development.