RESUMO
Endometriosis is found in 5-15% of women of reproductive age and is more frequent in relatives of women with the disease. Activation of KRAS results in de novo endometriosis in mice, however, activating KRAS mutations have not been identified in women. We screened 150 women with endometriosis for a polymorphism in a let-7 microRNA (miRNA) binding site in the 3'-UTR of KRAS and detected a KRAS variant allele in 31% of women with endometriosis as opposed to 5% of a large diverse control population. KRAS mRNA and protein expression were increased in cultured endometrial stromal cells of women with the KRAS variant. Increased KRAS protein was due to altered miRNA binding as demonstrated in reporter assays. Endometrial stromal cells from women with the KRAS variant showed increased proliferation and invasion. In a murine model, endometrial xenografts containing the KRAS variant demonstrated increased proliferation and decreased progesterone receptor levels. These findings suggest that an inherited polymorphism of a let-7 miRNA binding site in KRAS leads to abnormal endometrial growth and endometriosis. The LCS6 polymorphism is the first described genetic marker of endometriosis risk.
Assuntos
Endometriose/genética , MicroRNAs/metabolismo , Polimorfismo de Nucleotídeo Único , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Adulto , Alelos , Animais , Sítios de Ligação , Endometriose/metabolismo , Feminino , Humanos , Camundongos , Camundongos SCID , MicroRNAs/genética , Mutação , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas p21(ras) , Células Estromais/metabolismo , Adulto Jovem , Proteínas ras/química , Proteínas ras/metabolismoRESUMO
CONTEXT: Homeo box A10 (HOXA10) regulates endometrial receptivity and its expression is decreased in women with endometriosis. Although sex steroids regulate HOXA10, these hormones are unaltered in endometriosis. We hypothesized a role for microRNA in the regulation of HOXA10. OBJECTIVE: MicroRNA 135a and -b are small noncoding RNA with predicted targets that include HOXA10. We evaluated miR135a/b expression and HOXA10 regulation in endometrium from subjects with and without endometriosis. DESIGN: The design of the study was the measurement of miR135a/b expression by quantitative PCR and in vitro analysis of HOXA10 regulation. SETTING: The study was conducted at a university medical center. PATIENTS: Patients included 50 controls and 32 women with endometriosis. INTERVENTIONS: Study interventions included endometrial biopsies and in vitro transfection. MAIN OUTCOME MEASURES: miR135a/b and HOXA10 expression were measured in the study. RESULTS: All endometrial samples expressed miR135a and -b. miR135a expression in controls was increased during the proliferative phase, decreased at the time of ovulation, and increased during the luteal phase. Subjects with endometriosis had 3-fold higher expression of miR135a in the proliferative phase than controls. miR135b showed less variation across the menstrual cycle; however, it was significantly increased in women with endometriosis in the proliferative and secretory phases. HOXA10 expression was simultaneously repressed in the endometrium of women with endometriosis. Transfection of endometrial stromal cells with mir135a/b or miR135a/b inhibitors resulted in the altered expression of HOXA10 mRNA and protein. miR135a or -b decreased luciferase expression driven by the HOXA10 3' untranslated region containing the miR135 binding site. miR135a regulation of HOXA10 was absent in MCF-7 cells, demonstrating cell specificity. CONCLUSIONS: HOXA10 was aberrantly regulated in the endometrium of women with endometriosis by both miR135a and miR135b. Increased microRNA expression likely suppresses genes required for implantation.