Mandy L. King

Cdh1 Is Essential for Endometrial Differentiation, Gland Development, and Adult Function in the Mouse Uterus

ABSTRACT CDH1 is a cell-cell adhesion molecule expressed in the epithelium to coordinate key morphogenetic processes, establish cell polarity, and regulate epithelial differentiation and proliferation. To determine the role of CDH1 in the mouse uterus, Cdh1 was conditionally ablated by crossing Pgr-Cre and Cdh1-flox mice, and the phenotype was characterized. We found that loss of Cdh1 results in a disorganized cellular structure of the epithelium and ablation of endometrial glands in the neonatal uterus. Cdh1d/d mice lost adherens junctions (CTNNB1 and CTNNA1) and tight junctions (claudin, occludin, and ZO-1 proteins) in the neonatal uterus, leading to loss of epithelial cell-cell interaction. Ablation of Cdh1 induced abnormal epithelial proliferation and massive apoptosis, and disrupted Wnt and Hox gene expression in the neonatal uterus. Although the uteri of Cdh1d/d mice did not show any myometrial defects, ablation of Cdh1 inhibited expression of epithelial (cytokeratin 8) and stromal (CD10) markers. Cdh1d/d mice were infertile because of defects during implantation and decidualization. Furthermore, we showed in the model of conditional ablation of both Cdh1 and Trp53 in the uterus that interrupting cell cycle regulation through the loss of Cdh1 leads to abnormal uterine development. The uteri of Cdh1d/d Trp53d/d mice exhibited histological features of endometrial carcinomas with myometrial invasion. Collectively, these findings suggest that CDH1 has an important role in structural and functional development of the uterus as well as adult uterine function. CDH1 has a capacity to control cell fate by altering directional cell proliferation and apoptosis.

WNT7A regulates tumor growth and progression in ovarian cancer through the WNT/β-catenin pathway.

Abnormal activation the WNT/β-catenin signaling pathway has been associated with ovarian carcinomas, but a specific WNT ligand and pertinent downstream mechanisms are not fully understood. In this study, we found abundant WNT7A in the epithelium of serous ovarian carcinomas, but not detected in borderline and benign tumors, normal ovary, or endometrioid carcinomas. To characterize the role of WNT7A in ovarian tumor growth and progression, nude mice were injected either intraperitoneally or subcutaneously with WNT7A knocked down SKOV3.ip1 and overexpressed SKOV3 cells. In the intraperitoneal group, mice receiving SKOV3.ip1 cells with reduced WNT7A expression developed significantly fewer tumor lesions. Gross and histologic examination revealed greatly reduced invasion of WNT7A knockdown cells into intestinal mesentery and serosa compared with the control cells. Tumor growth was regulated by loss or overexpression of WNT7A in mice receiving subcutaneous injection as well. In vitro analysis of cell function revealed that cell proliferation, adhesion, and invasion were regulated by WNT7A. The activity of the T-cell factor/lymphoid enhancer factor (TCF/LEF) reporter was stimulated by overexpression of WNT7A in ovarian cancer cells. Cotransfection with WNT7A and FZD5 receptor further increased activity, and this effect was inhibited by cotransfection with SFRP2 or dominant negative TCF4. Overexpression of WNT7A stimulated matrix metalloproteinase 7 (MMP7) promoter, and mutation of TCF-binding sites in MMP7 promoter confirmed that activation of MMP7 promoter by WNT7A was mediated by β-catenin/TCF signaling. Collectively, these results suggest that reexpression of WNT7A during malignant transformation of ovarian epithelial cells plays a critical role in ovarian cancer progression mediated by WNT/β-catenin signaling pathway. Mol Cancer Res; 10(3); 469–82. ©2012 AACR.

WNT7A/β-catenin signaling induces FGF1 and influences sensitivity to niclosamide in ovarian cancer

We previously characterized the link between WNT7A and the progression of ovarian cancer. Other groups have identified FGF1 as a relevant risk factor in ovarian cancer. Here, we show a linkage between these two signaling pathways that may be exploited to improve treatment and prognosis of patients with ovarian cancer. High expression of WNT7A and FGF1 are correlated in ovarian carcinomas and poor overall patient survival. A chromatin immunoprecipitation assay demonstrated that WNT7A/β-catenin signaling directly regulates FGF1 expression via TCF binding elements in the FGF1-1C promoter locus. In vitro gene manipulation studies revealed that FGF1 is sufficient to drive the tumor-promoting effects of WNT7A. In vivo xenograft studies confirmed that the stable overexpression of WNT7A or FGF1 induced a significant increase in tumor incidence, whereas FGF1 knockdown in WNT7A overexpressing cells caused a significant reduction in tumor size. Niclosamide most efficiently abrogated WNT7A/β-catenin signaling in our model, inhibited β-catenin transcriptional activity and cell viability, and increased cell death. Furthermore, niclosamide decreased cell migration following an increase in E-cadherin subsequent to decreased levels of SLUG. The effects of niclosamide on cell functions were more potent in WNT7A-overexpressing cells. Oral niclosamide inhibited tumor growth and progression in an intraperitoneal xenograft mouse model representative of human ovarian cancer. Collectively, these results indicate that FGF1 is a direct downstream target of WNT7A/β-catenin signaling and this pathway has potential as a therapeutic target in ovarian cancer. Moreover, niclosamide is a promising inhibitor of this pathway and may have clinical relevance.

Extraction-Dependent Effects of American Ginseng (Panax quinquefolium) on Human Breast Cancer Cell Proliferation and Estrogen Receptor Activation

Hypothesis: Ginseng root extracts and the biologically active ginsenosides have been shown to inhibit proliferation of human cancer cell lines, including breast cancer. However, there are conflicting data that suggest that ginseng extracts (GEs) may or may not have estrogenic action, which might be contraindicated in individuals with estrogen-dependent cancers. The current study was designed to address the hypothesis that the extraction method of American ginseng ( Panax quinquefolium ) root will dictate its ability to produce an estrogenic response using the estrogen receptor (ER)-positive MCF-7 human breast cancer cell model. Methods: MCF-7 cells were treated with a wide concentration range of either methanol-(alc-GE) or water-extracted (w-GE) ginseng root for 6 days. Cells were grown in media containing either normal or charcoal-stripped fetal calf serum to limit exposure to exogenous estrogen. Thus, an increase in MCF-7 cell proliferation by GE indicated potential estrogenicity. This was confirmed by blocking GE-induced MCF-7 cell proliferation with ER antagonists ICI 182,780 (1 nM) and 4-hydroxytamoxifen (0.1 μM). Furthermore, the ability of GE to bind ERα or ERβ and stimulate estrogen-responsive genes was examined. Results: Alc-GE, but not w-GE, was able to increase MCF-7 cell proliferation at low concentrations (5-100 μg/mL) when cells were maintained under low-estrogen conditions. The stimulatory effect of alc-GE on MCF-7 cell proliferation was blocked by the ER antagonists ICI 182,780 or 4-hydroxyta-moxifen. At higher concentrations of GE, both extracts inhibited MCF-7 and ER-negative MDA-MB-231 cell proliferation regardless of media conditions. Binding assays demonstrated that alc-GE, but not w-GE, was able to bind ERα and ERβ. Alc-GE (50 μg/mL) also induced an approximate 2.5-fold increase in expression of the estrogen-responsive pS2 gene, as well as progesterone receptor (PgR) gene expression, whereas w-GE was without effect. Conclusion: These data indicate that low concentrations of alc-GE, but not w-GE, elicit estrogenic effects, as evidenced by increased MCF-7 cell proliferation, in a manner antagonized by ER antagonists, interactions of alc-GE with estrogen receptors, and increased expression of estrogen-responsive genes by alc-GE. Thus, discrepant results between different laboratories may be due to the type of GE being analyzed for estrogenic activity.

Loss of Cdh1 and Pten Accelerates Cellular Invasiveness and Angiogenesis in the Mouse Uterus

ABSTRACT E-cadherin (CDH1) is a cell adhesion molecule that coordinates key morphogenetic processes regulating cell growth, cell proliferation, and apoptosis. Loss of CDH1 is a trademark of the cellular event epithelial to mesenchymal transition, which increases the metastatic potential of malignant cells. PTEN is a tumor-suppressor gene commonly mutated in many human cancers, including endometrial cancer. In the mouse uterus, ablation of Pten induces epithelial hyperplasia, leading to endometrial carcinomas. However, loss of Pten alone does not affect longevity until around 5 mo. Similarly, conditional ablation of Cdh1 alone does not predispose mice to cancer. In this study, we characterized the impact of dual Cdh1 and Pten ablation (Cdh1d/d Ptend/d) in the mouse uterus. We observed that Cdh1d/d Ptend/d mice died at Postnatal Days 15–19 with massive blood loss. Their uteri were abnormally structured with curly horns, disorganized epithelial structure, and increased cell proliferation. Co-immunostaining of KRT8 and ACTA2 showed invasion of epithelial cells into the myometrium. Further, the uteri of Cdh1d/d Ptend/d mice had prevalent vascularization in both the endometrium and myometrium. We also observed reduced expression of estrogen and progesterone receptors, loss of cell adherens, and tight junction molecules (CTNNB1 and claudin), as well as activation of AKT in the uteri of Cdh1d/d Ptend/d mice. However, complex hyperplasia was not found in the uteri of Cdh1d/d Ptend/d mice. Collectively, these findings suggest that ablation of Pten with Cdh1 in the uterus accelerates cellular invasiveness and angiogenesis and causes early death.

WNT7A Regulation by miR-15b in Ovarian Cancer.

WNT signaling is well known to play an important role in the regulation of development, cell proliferation and cell differentiation in a wide variety of normal and cancerous tissues. Despite the wealth of knowledge concerning when and where various WNT genes are expressed and downstream events under their control, there is surprisingly little published evidence of how they are regulated. We have recently reported that aberrant WNT7A is observed in serous ovarian carcinomas, and WNT7A is the sole ligand accelerating ovarian tumor progression through CTNNB1 (β-catenin)/TCF signaling in the absence of CTNNB1 mutations. In the present study, we report that WNT7A is a direct target of miR-15b in ovarian cancer. We showed that a luciferase reporter containing the putative binding site of miR-15b in the WNT7A 3’-UTR was significantly repressed by miR-15b. Mutation of the putative binding site of miR-15b in the WNT7A 3’-UTR restored luciferase activity. Furthermore, miR-15b was able to repress increased levels of TOPFLASH activity by WNT7A, but not those induced by S33Y. Additionally, miR-15b dose-dependently decreased WNT7A expression. When we evaluated the prognostic impact of WNT7A and miR-15b expression using TCGA datasets, a significant inverse correlation in which high-expression of WNT7A and low-expression of miR-15b was associated with reduced survival rates of ovarian cancer patients. Treatment with decitabine dose-dependently increased miR-15b expression, and silencing of DNMT1 significantly increased miR-15b expression. These results suggest that WNT7A is post-transcriptionally regulated by miR-15b, which could be down-regulated by promoter hypermethylation, potentially via DNMT1, in ovarian cancer.

Loss of Cdh1 and Trp53 in the uterus induces chronic inflammation with modification of tumor microenvironment

Type II endometrial carcinomas (ECs) are estrogen independent, poorly differentiated tumors that behave in an aggressive manner. As TP53 mutation and CDH1 inactivation occur in 80% of human endometrial type II carcinomas, we hypothesized that mouse uteri lacking both Trp53 and Cdh1 would exhibit a phenotype indicative of neoplastic transformation. Mice with conditional ablation of Cdh1 and Trp53 (Cdh1d/dTrp53d/d) clearly demonstrate architectural features characteristic of type II ECs, including focal areas of papillary differentiation, protruding cytoplasm into the lumen (hobnailing) and severe nuclear atypia at 6 months of age. Further, Cdh1d/dTrp53d/d tumors in 12-month-old mice were highly aggressive, and metastasized to nearby and distant organs within the peritoneal cavity, such as abdominal lymph nodes, mesentery and peri-intestinal adipose tissues, demonstrating that tumorigenesis in this model proceeds through the universally recognized morphological intermediates associated with type II endometrial neoplasia. We also observed abundant cell proliferation and complex angiogenesis in the uteri of Cdh1d/dTrp53d/d mice. Our microarray analysis found that most of the genes differentially regulated in the uteri of Cdh1d/dTrp53d/d mice were involved in inflammatory responses. CD163 and Arg1, markers for tumor-associated macrophages, were also detected and increased in the uteri of Cdh1d/dTrp53d/d mice, suggesting that an inflammatory tumor microenvironment with immune cell recruitment is augmenting tumor development in Cdh1d/dTrp53d/d uteri. Further, inflammatory mediators secreted from CDH1-negative, TP53 mutant endometrial cancer cells induced normal macrophages to express inflammatory-related genes through activation of nuclear factor-κB signaling. These results indicate that absence of CDH1 and TP53 in endometrial cells initiates chronic inflammation, promotes tumor microenvironment development following the recruitment of macrophages and promotes aggressive ECs.