Over the last year, we have focused our investigations on the biology of the uterine epithelium and the regulation of the development of lung cancer using novel genetically engineered mouse models. With respect to the uterus, we investigated the role of the Progesterone Receptor (PGR), GATA binding protein 2 (GATA2), and Steroidogenic Factor 1 (SF1) in regulating uterine epithelial function. With respect to the lung, we investigated the role of mitogen inducible factor 6 (Mig-6) in the development of lung cancer. Below is our discussion on the progress on these investigations. Loss of PGR expression in the uterine epithelium during the preimplantation period is a marker for uterine receptivity and embryo attachment. We hypothesized that the decrease in PGR expression is necessary for successful embryo implantation. To test this hypothesis, PGR was constitutively expressed in the entire uterus and specifically in the uterine epithelium by generating the PGR (mPgrALsL/+) mouse. This mouse consists of PGR cDNA placed in a vector containing the hybrid chicken -actin cytomegalovirus promoter and a LoxP-STOP-LoxP cassette inserted into the murine ROSA26 locus. Expression of PGR (mPgrLsL/+) in the whole uterus (Pgr cre recombinase protein, Pgrcre) or uterine epithelium (wingless-type MMTV integration site family, member 7A, cre recombinase protein, Wnt7acre) resulted in infertility with defects in embryo attachment and stromal cell decidualization. Although uterine morphology appeared normal, the expression of forkhead box A2 (Foxa2), a marker for uterine glandular function, was decreased. Expression of critical PGRA target genes, Indian hedgehog (Ihh) and amphiregulin (Areg) were maintained through the window of receptivity while the estrogen receptor (Esr) target gene, leukemia inhibitory factor (Lif), a key regulator of embryo receptivity, was decreased. Transcriptomic and cistromic analysis of the mouse uterus at day 4.5 of pregnancy identified an altered group of genes regulating molecular transport proteins in the control of fluid and ion levels within the uterine interstitial space. Additionally, LIF and its receptor, LIFR, were discovered to be directly bound by PGRA in the inhibition of transcription. Therefore, downregulation of the PGRA isoform at the window of receptivity is necessary for a receptive environment for the attaching embryo. Altered progesterone responsiveness leads to female infertility and cancer, but the underlying mechanisms remain unclear. One transcription factor that is regulated by PGR is GATA2. Mice were generated with uterine-specific ablation of Gata2. These mice were infertile showing failures in embryo implantation, endometrial decidualization and uninhibited estrogen signaling. Gata2 deficiency results in reduced PGR expression and attenuated progesterone signaling, as evidenced by genome-wide expression profiling and chromatin immunoprecipitation. GATA2 not only occupies at and promotes expression of Pgr, but also regulates downstream progesterone responsive genes in conjunction with the PGR. Additionally, Gata2 knockout uteri exhibit abnormal luminal epithelia with ectopic transformation related protein 63 (TRP63) expressing squamous cells and a cancer related molecular profile in a progesterone independent manner. Lastly, we found a conserved GATA2-PGR regulatory network in both human and mouse, based on gene signature and path analyses using gene expression profiles of human endometrial tissues. In conclusion, uterine Gata2 regulates a key regulatory network of gene expression for progesterone signaling at the early pregnancy stage. Epigenetic silencing of SF1 is lost in endometriosis, potentially contributing to de novo local steroidogenesis favoring inflammation and growth of ectopic endometrial tissue. In this study, we examine the impact of SF1 expression in the eutopic uterus by a novel mouse model that conditionally expresses SF1 in endometrium. In vivo SF1 expression promoted the development of enlarged endometrial glands and attenuated estrogen and progesterone responsiveness. Endometriosis induction by auto-transplantation of uterine tissue to the mesenteric membrane resulted in the increase in size of ectopic lesions from SF1 expressing mice. By integrating the SF1-dependent transcriptome with the whole genome binding profile of SF1, we identified uterine specific SF1-regulated genes involved in wingless (Wnt) and Pgr-Hedgehog-COUP-TFII signaling for gland development and epithelium-stroma interaction, respectively. The present results indicate that SF1 directly contributes to the abnormal uterine gland morphogenesis, an inhibition of steroid hormone signaling, and activation of an immune response, in addition to previously postulated estrogen production. Mig-6 is a small adaptor protein modulating signaling in cells to regulate the growth and differentiation in multiple tissues. We have previously shown that Mig-6, is critical for lung development. Ablation of Mig-6 resulted in partial neonatal lethality with the surviving mice showing defects in pulmonary biology in as an adult. Decreased Mig-6 expression is associated with enhanced drug resistance in cells with mutation of the regulatory protein Kras. However, the in vivo interaction between Mig-6 and Kirsten rat sarcoma viral oncogene (Kras), the most frequently mutated gene in lung adenocarcinoma, remains unclear. Using Clara cell secretory protein-Cre (CCSPCre) to specifically activate expression of the oncogenic KrasG12D in lung, we found that Mig-6 expression is decreased in CCSPCreKrasG12D-induced lung tumors. Ablation of Mig-6 in the KrasG12D background leads to airway hyperplasia, enhanced tumorigenesis, and reduced life expectancy. The compound mutation also results in attenuated apoptosis, heightened inflammatory responses, and elevated phosphorylation of the epidermal growth factor receptor, erb-b2 receptor tyrosine kinase 4 (ERBB4). In summary, our findings indicate that Mig-6 deficiency facilitates KrasG12D-induced lung tumors through suppressing apoptosis and activating the ERBB4 pathway.
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