Ovarian insufficiency and CTNNB1 mutations drive malignant transformation of endometrial hyperplasia with altered PTEN/PI3K activities.

Endometrioid endometrial carcinomas (EECs) carry multiple driver mutations even when they are low grade. However, the biological significance of these concurrent mutations is unknown. We explored the interactions among three signature EEC mutations: loss-of-function (LOF) mutations in PTEN, gain-of-function (GOF) mutations of phosphoinositide 3-kinase (PI3K), and CTNNB1 exon 3 mutations, utilizing in vivo mutagenesis of the mouse uterine epithelium. While epithelial cells with a monoallelic mutation in any one of three genes failed to propagate in the endometrium, any combination of two or more mutant alleles promoted the growth of epithelium, causing simple hyperplasia, in a dose-dependent manner. Notably, Ctnnb1 exon 3 deletion significantly increased the size of hyperplastic lesions by promoting the growth of PTEN LOF and/or PI3K GOF mutant cells through the activation of neoadenogenesis pathways. Although these three mutations were insufficient to cause EEC in intact female mice, castration triggered malignant transformation, leading to myometrial invasion and serosal metastasis. Treatment of castrated mice with progesterone or estradiol attenuated the neoplastic transformation. This study demonstrates that multiple driver mutations are required for premalignant cells to break the growth-repressing field effect of normal endometrium maintained by ovarian steroids and that CTNNB1 exon 3 mutations play critical roles in the growth of preneoplastic cells within the endometrium of premenopausal women and in the myometrial invasion of EECs in menopausal women.

Patient-derived xenograft model for uterine leiomyoma by sub-renal capsule grafting.

Uterine leiomyoma (UL) or fibroid is a benign smooth muscle tumor of the myometrium with a lifetime incidence of approximately 70%. ULs often require medical intervention due to severe symptoms such as heavy menstrual bleeding and abdominal pain. Although the most common and effective management of ULs is surgical removal, the invasive surgical procedure imposes physical and psychological burdens on the patients. Moreover, the economic burden of UL on health care system is enormous due to the high cost of surgeries. Thus, therapeutic options with long-term efficacy to replace surgical management are urgently needed. For the development of such medical options, reliable preclinical research models are imperative. Ex vivo culture of UL cells has been the primary research model for decades. However, recent studies demonstrated that primary cell culture is not a suitable model for UL research, as primary cultures of ULs mostly consist of non-tumor fibroblasts. Here we describe the protocol for patient-derived xenograft of UL, which faithfully replicates the phenotypes of human UL in situ.

Cell autonomous phosphoinositide 3-kinase activation in oocytes disrupts normal ovarian function through promoting survival and overgrowth of ovarian follicles.

In this study, we explored the effects of oocytic phosphoinositide 3-kinase (PI3K) activation on folliculogensis by generating transgenic mice, in which the oocyte-specific Cre-recombinase induces the expression of constitutively active mutant PI3K during the formation of primordial follicles. The ovaries of neonatal transgenic (Cre+) mice showed significantly reduced apoptosis in follicles, which resulted in an excess number of follicles per ovary. Thus, the elevation of phosphatidylinositol (3,4,5)-trisphosphate levels within oocytes promotes the survival of follicles during neonatal development. Despite the increase in AKT phosphorylation, primordial follicles in neonatal Cre+ mice remained dormant demonstrating a nuclear accumulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). These primordial follicles containing a high level of nuclear PTEN persisted in postpubertal females, suggesting that PTEN is the dominant factor in the maintenance of female reproductive lifespan through the regulation of primordial follicle recruitment. Although the oocytic PI3K activity and PTEN levels were elevated, the activation of primordial follicles and the subsequent accumulation of antral follicles with developmentally competent oocytes progressed normally in prepubertal Cre+ mice. However, mature Cre+ female mice were anovulatory. Because postnatal day 50 Cre+ mice released cumulus-oocyte complexes with developmentally competent oocytes in response to super-ovulation treatment, the anovulatory phenotype was not due to follicular defects but rather endocrine abnormalities, which were likely caused by the excess number of overgrown follicles. Our current study has elucidated the critical role of oocytic PI3K activity in follicular function, as well as the presence of a PTEN-mediated mechanism in the prevention of immature follicle activation.

Anti-miR182 reduces ovarian cancer burden, invasion, and metastasis: an in vivo study in orthotopic xenografts of nude mice.

High-grade serous ovarian carcinoma (HGSOC) is a fatal disease, and its grave outcome is largely because of widespread metastasis at the time of diagnosis. Current chemotherapies reduce tumor burden, but they do not provide long-term benefits for patients with cancer. The aggressive tumor growth and metastatic behavior characteristic of these tumors demand novel treatment options such as anti-microRNA treatment, which is emerging as a potential modality for cancer therapy. MicroRNA-182 (miR182) overexpression contributes to aggressive ovarian cancer, largely by its negative regulation of multiple tumor suppressor genes involved in tumor growth, invasion, metastasis, and DNA instability. In this study, we examined the therapeutic potential of anti-miR182 utilizing the animal orthotopic model to mimic human ovarian cancer using ovarian cancer cells SKOV3 (intrabursal xenografts) and OVCAR3 (intraperitoneal injection). These models provide a valuable model system for the investigation of ovarian cancer therapy in vivo. Through a combination of imaging, histological, and molecular analyses, we found that anti-miR182 treatment can significantly reduce tumor burden (size), local invasion, and distant metastasis compared with its control in both models. The bases of anti-miR182 treatment are mainly through the restoration of miR182 target expression, including but not limited to BRCA1, FOXO3a, HMGA2, and MTSS1. Overall, our results strongly suggest that anti-miR182 can potentially be used as a therapeutic modality in treating HGSOC.

Down-regulation of miR-29b is essential for pathogenesis of uterine leiomyoma.

Uterine leiomyomata (LMs) are the most common tumor affecting the female reproductive organs. The most notable pathophysiologic feature of this tumor is the excessive accumulation of rigid extracellular matrix (ECM) composed mainly of collagen types I and III. It is believed that the rigidity of the collagen-rich ECM causes symptoms such as abnormal bleeding and pelvic pain/pressure. However, the molecular pathogenesis for this ECM-rich tumor has yet to be elucidated. We have established that miR-29b was consistently down-regulated in LM compared with myometrium (MM). Hence, the function of miR-29b in LM was examined in vivo using adult female ovariectomized NOD-scid IL2Rγ(null) mice for subrenal xenograft models. In LM xenografts, restoring miR-29b inhibited the accumulation of ECM and the development of solid tumors. Although the miR-29b knockdown in MM cells increased the expression of collagens, it did not transform MM cells into tumorigenic, indicating that the down-regulation of miR-29b is essential but not sufficient for LM tumorigenesis. In addition, 17ß-estradiol and progesterone down-regulated miR-29b and up-regulated mRNAs for multiple collagens in LM xenografts. Thus, we conclude that ECM production in LMs is regulated by steroid hormones via down-regulation of miR-29b, which is one of the mechanisms underlying the excessive accumulation of ECM.

Paracrine activation of WNT/ß-catenin pathway in uterine leiomyoma stem cells promotes tumor growth.

Uterine leiomyomas are extremely common estrogen and progesterone-dependent tumors of the myometrium and cause irregular uterine bleeding, severe anemia, and recurrent pregnancy loss in 15-30% of reproductive-age women. Each leiomyoma is thought to arise from a single mutated myometrial smooth muscle stem cell. Leiomyoma side-population (LMSP) cells comprising 1% of all tumor cells and displaying tumor-initiating stem cell characteristics are essential for estrogen- and progesterone-dependent in vivo growth of tumors, although they have remarkably lower estrogen/progesterone receptor levels than mature myometrial or leiomyoma cells. However, how estrogen/progesterone regulates the growth of LMSP cells via mature neighboring cells is unknown. Here, we demonstrate a critical paracrine role of the wingless-type (WNT)/ß-catenin pathway in estrogen/progesterone-dependent tumorigenesis, involving LMSP and differentiated myometrial or leiomyoma cells. Estrogen/progesterone treatment of mature myometrial cells induced expression of WNT11 and WNT16, which remained constitutively elevated in leiomyoma tissues. In LMSP cells cocultured with mature myometrial cells, estrogen-progesterone selectively induced nuclear translocation of ß-catenin and induced transcriptional activity of its heterodimeric partner T-cell factor and their target gene AXIN2, leading to the proliferation of LMSP cells. This effect could be blocked by a WNT antagonist. Ectopic expression of inhibitor of ß-catenin and T-cell factor 4 in LMSP cells, but not in mature leiomyoma cells, blocked the estrogen/progesterone-dependent growth of human tumors in vivo. We uncovered a paracrine role of the WNT/ß-catenin pathway that enables mature myometrial or leiomyoma cells to send mitogenic signals to neighboring tissue stem cells in response to estrogen and progesterone, leading to the growth of uterine leiomyomas.

Role of stem cells in human uterine leiomyoma growth.

BACKGROUND: Uterine leiomyoma is the most common benign tumor in reproductive-age women. Each leiomyoma is thought to be a benign monoclonal tumor arising from a single transformed myometrial smooth muscle cell; however, it is not known what leiomyoma cell type is responsible for tumor growth. Thus, we tested the hypothesis that a distinct stem/reservoir cell-enriched population, designated as the leiomyoma-derived side population (LMSP), is responsible for cell proliferation and tumor growth. PRINCIPAL FINDINGS: LMSP comprised approximately 1% of all leiomyoma and 2% of all myometrium-derived cells. All LMSP and leiomyoma-derived main population (LMMP) but none of the side or main population cells isolated from adjacent myometrium carried a mediator complex subunit 12 mutation, a genetic marker of neoplastic transformation. Messenger RNA levels for estrogen receptor-α, progesterone receptor and smooth muscle cell markers were barely detectable and significantly lower in the LMSP compared with the LMMP. LMSP alone did not attach or survive in monolayer culture in the presence or absence of estradiol and progestin, whereas LMMP readily grew under these conditions. LMSP did attach and survive when directly mixed with unsorted myometrial cells in monolayer culture. After resorting and reculturing, LMSP gained full potential of proliferation. Intriguingly, xenografts comprised of LMSP and unsorted myometrial smooth muscle cells grew into relatively large tumors (3.67 ± 1.07 mm(3)), whereas xenografts comprised of LMMP and unsorted myometrial smooth muscle cells produced smaller tumors (0.54 ± 0.20 mm(3), p<0.05, n = 10 paired patient samples). LMSP xenografts displayed significantly higher proliferative activity compared with LMMP xenografts (p<0.05). CONCLUSIONS: Our data suggest that LMSP, which have stem/reservoir cell characteristics, are necessary for in vivo growth of leiomyoma xenograft tumors. Lower estrogen and progesterone receptor levels in LMSP suggests an indirect paracrine effect of steroid hormones on stem cells via the mature neighboring cells.

ΔNp63 knockout mice reveal its indispensable role as a master regulator of epithelial development and differentiation.

The transcription factor p63 is important in the development of the skin as p63-null mice exhibit striking defects in embryonic epidermal morphogenesis. Understanding the mechanisms that underlie this phenotype is complicated by the existence of multiple p63 isoforms, including TAp63 and ΔNp63. To investigate the role of ΔNp63 in epidermal morphogenesis we generated ΔNp63 knock-in mice in which the ΔNp63-specific exon is replaced by GFP. Homozygous ΔNp63(gfp/gfp) animals exhibit severe developmental anomalies including truncated forelimbs and the absence of hind limbs, largely phenocopying existing knockouts in which all p63 isoforms are deleted. ΔNp63-null animals show a poorly developed stratified epidermis comprising isolated clusters of disorganized epithelial cells. Despite the failure to develop a mature stratified epidermis, the patches of ΔNp63-null keratinocytes are able to stratify and undergo a program of terminal differentiation. However, we observe premature expression of markers associated with terminal differentiation, which is unique to ΔNp63-null animals and not evident in the skin of mice lacking all p63 isoforms. We posit that the dysregulated and accelerated keratinocyte differentiation phenotype is driven by significant alterations in the expression of key components of the Notch signaling pathway, some of which are direct transcriptional targets of ΔNp63 as demonstrated by ChIP experiments. The analysis of ΔNp63(gfp/gfp) knockout mice reaffirms the indispensable role of the ΔN isoform of p63 in epithelial biology and confirms that ΔNp63-null keratinocytes are capable of committing to an epidermal cell lineage, but are likely to suffer from diminished renewal capacity and an altered differentiation fate.

Progesterone is essential for maintenance and growth of uterine leiomyoma.

Uterine leiomyomata (ULs) represent the most common tumor in women and can cause abnormal uterine bleeding, large pelvic masses, and recurrent pregnancy loss. Although the dependency of UL growth on ovarian steroids is well established, the relative contributions of 17beta-estradiol and progesterone are yet to be clarified. Conventionally, estradiol has been considered the primary stimulus for UL growth, and studies with cell culture and animal models support this concept. In contrast, no research model has clearly demonstrated a requirement of progesterone in UL growth despite accumulating clinical evidence for the essential role of progesterone in this tumor. To elucidate the functions of ovarian steroids in UL, we established a xenograft model reflecting characteristics of these tumors by grafting human UL tissue beneath the renal capsule of immunodeficient mice. Leiomyoma xenografts increased in size in response to estradiol plus progesterone through cell proliferation and volume increase in cellular and extracellular components. The xenograft growth induced by estradiol plus progesterone was blocked by the antiprogestin RU486. Furthermore, the volume of established UL xenografts decreased significantly after progesterone withdrawal. Surprisingly, treatment with estradiol alone neither increased nor maintained the tumor size. Although not mitogenic by itself, estradiol induced expression of progesterone receptor and supported progesterone action on leiomyoma xenografts. Taken together, our findings define that volume maintenance and growth of human UL are progesterone dependent.