Abstract 3674: MIG-6 suppresses epithelial cell proliferation via inhibiting AKT phosphorylation during endometrial tumorigenesis

Endometrial cancer is the most frequently diagnosed malignancy of the female genital tract. Hysterectomy is typically the first line therapeutic strategy for endometrial cancer. However, there is an increasing demand for nonsurgical approaches for endometrial cancer, especially for women of reproductive age with endometrial cancer who wish to preserve their fertility. Most endometrial cancers are characterized by actively proliferating epithelial cells, increased AKT signaling and association with prolonged, unopposed E2 exposure.

Mitogen-inducible gene 6 (Mig-6) is an important mediator of progesterone receptor action in the murine uterus. As P4 achieves the inhibition of proliferation by coordinating stromal-epithelial cross-talk, we generated a mouse model in which we specifically ablate epithelial endometrial Mig-6 using Sprr2f-cre mice (Sprr2fcre+Mig-6f/f) to understand the role of epithelial Mig-6 in the uterus. Sprr2fcre+Mig-6f/f mice displayed endometrial hyperplasia upon 10 weeks of age and develop endometrial cancer by E2 treatment for 3 months. The levels of epithelial proliferation by Ki67 staining were significantly increased in epithelial cells of Sprr2fcre+Mig-6f/f mice at 10 weeks of age. The levels of phospho-AKT and phospho-S6, downstream of AKT, were remarkably higher in Sprr2fcre+Mig-6f/f mice. Interestingly, the hyperplasia exhibited by Sprr2fcre+Mig-6f/f mice was prevented by P4 treatment for 1 week in morphological and histological analysis. Aberrant activation of proliferation as well as AKT signaling was decreased in the epithelium of Sprr2fcre+Mig-6f/f mice by P4 treatment. Furthermore, we identified that MIG-6 inhibits AKT phosphorylation in human endometrial cancer cells. These data suggest that stromal P4 signaling including Mig-6 is critical in regulation of epithelial cell proliferation via regulating AKT phosphorylation during endometrial cancer development and progression.

(This work was supported by American Cancer Society Research Grant, RSG-12-084-01-TBG to J.W.J.)

Citation Format: Tae Hoon Kim, Jung-Yoon Yoo, Jae Hee Lee, Byung Gak Kim, Russell R. Broaddus, Jae-Wook Jeong. MIG-6 suppresses epithelial cell proliferation via inhibiting AKT phosphorylation during endometrial tumorigenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3674.

Protein Inhibitor of Activated STAT3 (PIAS3) Is Down-Regulated in Eutopic Endometrium of Women with Endometriosis

Endometriosis is a major cause of chronic pelvic pain and infertility. Activation of STAT3 appears central to the inflammatory phenotype of eutopic endometrium in women with endometriosis. However, the molecular mechanism by which this occurs remains unknown. Our objective is to determine how STAT3 activity is regulated in endometriosis. Protein inhibitor of activated STAT3 (PIAS3) is a negative regulator of STAT3 activity. We examined the levels of PIAS3 in endometrium from women with and without endometriosis using Western blot analysis and immunohistochemistry. Levels of PIAS3 are significantly lower, in contrast with phosphorylation of STAT3, in women with endometriosis compared to women without endometriosis. Furthermore, induction of endometriosis in the baboon showed a significant reduction of PIAS3 expression during the progression of the disease. Interferon-γ (INFγ) reduces PIAS3 protein levels and increases phospho-STAT3 levels through CXCL10 in endometrial cells, Ishikawa, and 12Z cells. These results suggest that attenuation of PIAS3 causes aberrant activation of STAT3 in endometriosis, leading to inflammatory changes that may impair fertility or cause pain.

Local and systemic factors and implantation: what is the evidence?

Significant progress has been made in the understanding of embryonic competence and endometrial receptivity since the inception of assisted reproductive technology. The endometrium is a highly dynamic tissue that plays a crucial role in the establishment and maintenance of normal pregnancy. In response to steroid sex hormones, the endometrium undergoes marked changes during the menstrual cycle that are critical for acceptance of the nascent embryo. There is also a wide body of literature on systemic factors that impact assisted reproductive technology outcomes. Patient prognosis is impacted by an array of factors that tip the scales in her favor or against success. Recognizing the local and systemic factors will allow clinicians to better understand and optimize the maternal environment at the time of implantation. This review will address the current literature on endometrial and systemic factors related to impaired implantation and highlight recent advances in this area of reproductive medicine.

Role of Mig-6 in hepatic glucose metabolism

BACKGROUND

Mitogen-inducible gene 6 (Mig-6) has an important role in the regulation of cholesterol homeostasis and bile acid synthesis. However, the physiological functions of Mig-6 in the liver remain poorly understood.

METHODS

To investigate Mig-6 functioning in the liver, we used conditionally ablated Mig-6 using the Albumin-Cre mouse model (Alb(cre/+) Mig-6(f/f) ; Mig-6(d/d) ). Male mice were killed after a 24-h fast and refed after 24 h fasting. Fasting glucose and insulin levels were measured and western blot analyses were performed to determine epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK) 1/2, AKT, mammalian target of rapamycin (mTOR), c-Jun N-terminal kinase (JNK), and Insulin receptor substrate-1 (IRS-1) in liver tissue samples. In addition, human hepatocellular carcinoma HepG2 cells were transfected with Mig-6 short interference (si) RNA before western blot analysis.

RESULTS

Serum fasting glucose levels were significantly higher in Mig-6(d/d) versus Mig-6(f/f) mice. On an insulin tolerance test, insulin sensitivity was decreased in Mig-6(d/d) versus Mig-6(f/f) mice. Furthermore, hepatic expression of the glucokinase (Gck), glucose-6-phosphatase (G6pc), and phosphoenolpyruvate carboxykinase 1 (Pck1) genes was decreased significantly in Mig-6(d/d) mice. Phosphorylation of EGFR, ERK1/2, AKT, mTOR, JNK, and IRS-1 was increased in Mig-6(d/d) compared with Mig-6(f/f) mice.

CONCLUSION

Liver-specific ablation of Mig-6 caused hyperglycemia by hepatic insulin resistance. Increased EGFR signaling following Mig-6 ablation activated JNK and eventually induced insulin resistance by increasing phosphorylation of IRS-1 at serine 307. This is the first report of Mig-6 involvement in hepatic insulin resistance and a new mechanism that explains hepatic insulin resistance.

Field Effect and Strongly Localized Carriers in the Metal-Insulator Transition Material VO(2)

The intrinsic field effect, the change in surface conductance with an applied transverse electric field, of prototypal strongly correlated VO(2) has remained elusive. Here we report its measurement enabled by epitaxial VO(2) and atomic layer deposited high-κ dielectrics. Oxygen migration, joule heating, and the linked field-induced phase transition are precluded. The field effect can be understood in terms of field-induced carriers with densities up to ∼5×10(13)  cm(-2) which are trongly localized, as shown by their low, thermally activated mobility (∼1×10(-3)  cm(2)/V s at 300 K). These carriers show behavior consistent with that of Holstein polarons and strongly impact the (opto)electronics of VO(2).

ARID1A Is Essential for Endometrial Function during Early Pregnancy

AT-rich interactive domain 1A gene (ARID1A) loss is a frequent event in endometriosis-associated ovarian carcinomas. Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside the uterus, and 50% of women with endometriosis are infertile. ARID1A protein levels were significantly lower in the eutopic endometrium of women with endometriosis compared to women without endometriosis. However, an understanding of the physiological effects of ARID1A loss remains quite poor, and the function of Arid1a in the female reproductive tract has remained elusive. In order to understand the role of Arid1a in the uterus, we have generated mice with conditional ablation of Arid1a in the PGR positive cells (Pgrcre/+Arid1af/f; Arid1ad/d). Ovarian function and uterine development of Arid1ad/d mice were normal. However, Arid1ad/d mice were sterile due to defective embryo implantation and decidualization. The epithelial proliferation was significantly increased in Arid1ad/d mice compared to control mice. Enhanced epithelial estrogen activity and reduced epithelial PGR expression, which impedes maturation of the receptive uterus, was observed in Arid1ad/d mice at the peri-implantation period. The microarray analysis revealed that ARID1A represses the genes related to cell cycle and DNA replication. We showed that ARID1A positively regulates Klf15 expression with PGR to inhibit epithelial proliferation at peri-implantation. Our results suggest that Arid1a has a critical role in modulating epithelial proliferation which is a critical requisite for fertility. This finding provides a new signaling pathway for steroid hormone regulation in female reproductive biology and furthers our understanding of the molecular mechanisms that underlie dysregulation of hormonal signaling in human reproductive disorders such as endometriosis.

Altered expression of microRNA-451 in eutopic endometrium of baboons (Papio anubis) with endometriosis

STUDY QUESTION

Are microRNAs (miRs) altered in the eutopic endometrium (EuE) of baboons following the induction of endometriosis?

SUMMARY ANSWER

Induction of endometriosis causes significant changes in the expression of eight miRs, including miR-451, in the baboon endometrium as early as 3 months following induction of the disease.

WHAT IS KNOWN ALREADY

Endometriosis is one of the most common gynecological disorders and causes chronic pelvic pain and infertility in women of reproductive age. Altered expression of miRs has been reported in women and has been suggested to play an important role in the pathophysiology of several gynecological disorders including endometriosis.

STUDY DESIGN, SIZE, DURATION

EuE was obtained from the same group of baboons before and 3 months after the induction of endometriosis. The altered expression of miR-451 was validated in the eutopic and ectopic endometrium of additional baboons between 3 and 15 months following disease induction. Timed endometrial biopsies from women with and without endometriosis were also used to validate the expression of miR-451.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total RNA was extracted from EuE samples before and after the induction of endometriosis, and miRNA expression was analyzed using a 8 × 15 K miR microarray. Microarray signal data were preprocessed by AgiMiRna software, and an empirical Bayes model was used to estimate the changes. The present study focused on quantitative RT-PCR validation of the microarray data, specifically on miR-451 and its target genes in both baboons (n = 3) and women [control (n = 7) and endometriosis (n = 19)]. Descriptive and correlative analysis of miR-451 and target gene expression was conducted using in situ hybridization and immunohistochemistry, while functional analysis utilized an in vitro 3' untranslated region (UTR) luciferase assay and overexpression of miR-451 in human endometrial and endometriotic cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

Induction of endometriosis results in the altered expression of miR-451, -141, -29c, -21, -424, -19b, -200a and -181a in the baboon endometrium. In the baboon, induction of endometriosis significantly decreased the expression of miR-451 at 3 months (P < 0.001), which was also associated with increased expression of its target gene YWHAZ (14.3.3ζ). A similar significant (P < 0.0001) decrease in miR-451 expression was observed in women with endometriosis. The 3' UTR luciferase assay confirmed the regulation of YWHAZ expression by miR-451. Furthermore, overexpression of miR-451 in 12Z cells (immortalized human endometriotic epithelial cell line) led to the decreased expression of its target YWHAZ and this was correlated with decreased cell proliferation.

LIMITATIONS, REASONS FOR CAUTION

The study focused only on miR-451 and one of its targets, namely YWHAZ. A single miR could target number of genes and a single gene could also be regulated by number of miRs; hence, it is possible that other miRs and their regulated genes may contribute to the pathophysiology of endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that the presence of ectopic lesions in baboon causes changes in EuE miR expression as early as 3 months postinduction of the disease, and some of these changes may persist throughout the course of the disease. We propose that the marked down-regulation of miR-451 in both baboons and women with endometriosis increases the expression of multiple target genes. Increased expression of one of the target genes, YWHAZ, increases proliferation, likely contributing to the pathophysiology of the disease.

A role for site-specific phosphorylation of mouse progesterone receptor at serine 191 in vivo

Progesterone receptors (PRs) are phosphorylated on multiple sites, and a variety of roles for phosphorylation have been suggested by cell-based studies. Previous studies using PR-null mice have shown that PR plays an important role in female fertility, regulation of uterine growth, the uterine decidualization response, and proliferation as well as ductal side-branching and alveologenesis in the mammary gland. To study the role of PR phosphorylation in vivo, a mouse was engineered with homozygous replacement of PR with a PR serine-to-alanine mutation at amino acid 191. No overt phenotypes were observed in the mammary glands or uteri of PR S191A treated with progesterone (P4). In contrast, although PR S191A mice were fertile, litters were 19% smaller than wild type and the estrous cycle was lengthened slightly. Moreover, P4-dependent gene regulation in primary mammary epithelial cells (MECs) was altered in a gene-selective manner. MECs derived from wild type and PR S191A mice were grown in a three-dimensional culture. Both formed acinar structures that were morphologically similar, and proliferation was stimulated equally by P4. However, P4 induction of receptor activator of nuclear factor-κB ligand and calcitonin was selectively reduced in S191A cultures. These differences were confirmed in freshly isolated MECs. Chromatin immunoprecipitation analysis showed that the binding of S191A PR to some of the receptor activator of nuclear factor-κB ligand enhancers and a calcitonin enhancer was substantially reduced. Thus, the elimination of a single phosphorylation site is sufficient to modulate PR activity in vivo. PR contains many phosphorylation sites, and the coordinate regulation of multiple sites is a potential mechanism for selective modulation of PR function.

DNAJB1 negatively regulates MIG6 to promote epidermal growth factor receptor signaling

Mitogen-inducible gene 6 (MIG6) is a tumor suppressor implicated in the development of human cancers; however, the regulatory mechanisms of MIG6 remain unknown. Here, using a yeast two-hybrid screen, we identified DnaJ homolog subfamily B member I (DNAJB1) as a novel MIG6-interacting protein. We found that DNAJB1 binds to and decreases MIG6 protein, but not mRNA, levels. DNAJB1 overexpression dosage-dependently decreased MIG6 protein levels. Conversely, DNAJB1 knockdown increased MIG6 protein levels. DNAJB1 destabilizes MIG6 by enhancing K48-linked ubiquitination of MIG6. However, knocking-down of DNAJB1 reduced the ubiquitination of MIG6. DNAJB1 positively regulates the epidermal growth factor receptors (EGFR) signaling pathway via destabilization of MIG6; however, DNAJB1 knockdown diminishes activation of EGFR signaling as well as elevation of MIG6. Importantly, the increased levels of MIG6 by DNAJB1 knockdown greatly enhanced the gefitinib sensitivity in A549 cells. Thus, our study provides a new molecular mechanism to regulate EGFR signaling through modulation of MIG6 by DNAJB1 as a negative regulator.

Abstract 2069: Stromal-epithelial crosstalk of Mig-6 has an important role for tumor suppression via progesterone in endometrial cancer

Endometrial cancer is the most common malignancy of the female genital tract. This disease is commonly caused by an imbalance of progesterone (P4) and estrogen (E2) action that E2 stimulates proliferation of uterine epithelial cells while P4 is inhibitory to estrogen-mediated proliferation of the epithelium. Endometrial hyperplasia is also associated with endometrial cancer, which is a proliferative process in epithelium by E2. Responsiveness of progesterone is required to treat endometrial cancer and preserve the fertility of patients. Furthermore, PR expression in the uteri of patients with endometrial cancer has been used as an indicator for a first-rate prognosis. However, more than 30% of patients do not respond to progesterone treatment as a result of progesterone resistance and the mechanism of progesterone resistance is still unknown. Thus, identifying the mechanism of progesterone in endometrial cancer is essential to improve the therapy of this disease. Mitogen-inducible gene 6 (Mig-6) is an important mediator of progesterone receptor (PR) action in the murine uterus. As P4 achieves the inhibition of proliferation by coordinating stromal-epithelial cross-talk, we generated a mouse model in which we specifically ablate epithelial endometrial Mig-6 using Sprr2f-cre mice (Sprr2fcre+ Mig-6f/f) to understand the role of epithelial Mig-6 in the uterus. Sprr2fcre+ Mig-6f/f mice displayed endometrial hyperplasia upon 10 weeks of age and develop endometrial cancer by E2 treatment for 3 months. Interestingly, the hyperplasia exhibited by Sprr2fcre+ Mig-6f/f mice was prevented by P4 treatment for 1 week in morphological and histological analysis. Proliferation decreased in the glandular epithelium of Sprr2fcre+ Mig-6f/f mice by P4, and apoptotic signal was also reduced. The expressions of stromal PR and its target genes were induced in Sprr2fcre+ Mig-6f/f mice after P4 treatment, indicating that P4-induced stromal Mig-6 can prevent the hyperplasia via regulating steroid hormonal signaling. This study suggested that stromal-epithelial communication of Mig-6 is critical in tumor suppressor function via regulating steroid hormonal signaling by progesterone. (This work was supported by American Cancer Society Research Grant, RSG-12-084-01-TBG to J.W.J.)

Citation Format: Tae Hoon Kim, Byung Gak Kim, Jung-Yoon Yoo, Jae Hee Lee, Diego H. Castrillon, Jae-Wook Jeong. Stromal-epithelial crosstalk of Mig-6 has an important role for tumor suppression via progesterone in endometrial cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2069. doi:10.1158/1538-7445.AM2015-2069

Programmed cell death 5 mediates HDAC3 decay to promote genotoxic stress response

The inhibition of p53 activity by histone deacetylase 3 (HDAC3) has been reported, but the precise molecular mechanism is unknown. Here we show that programmed cell death 5 (PDCD5) selectively mediates HDAC3 dissociation from p53, which induces HDAC3 cleavage and ubiquitin-dependent proteasomal degradation. Casein kinase 2 alpha phosphorylates PDCD5 at Ser-119 to enhance its stability and importin 13-mediated nuclear translocation of PDCD5. Genetic deletion of PDCD5 abrogates etoposide (ET)-induced p53 stabilization and HDAC3 cleavage, indicating an essential role of PDCD5 in p53 activation. Restoration of PDCD5^WT in PDCD5^−/− MEFs restores ET-induced HDAC3 cleavage. Reduction of both PDCD5 and p53, but not reduction of either protein alone, significantly enhances in vivo tumorigenicity of AGS gastric cancer cells and correlates with poor prognosis in gastric cancer patients. Our results define a mechanism for p53 activation via PDCD5-dependent HDAC3 decay under genotoxic stress conditions.

The tumour suppressor p53 is known to be inhibited by histone deacetylase 3 but the molecular mechanism is poorly understood. Here Choi et al. show regulation by programmed cell death 5 and an essential role in activating p53 following DNA damage.

Aberrant activation of signal transducer and activator of transcription-3 (STAT3) signaling in endometriosis

STUDY QUESTION

Are STAT3 signaling molecules differentially expressed in endometriosis?

SUMMARY ANSWER

Levels of phospho-STAT3 and HIF1A, its downstream signaling molecule, are significantly higher in eutopic endometrium from women with endometriosis when compared with women without the disease.

WHAT IS KNOWN ALREADY

Endometriosis is an estrogen-dependent inflammatory condition. Interleukin 6 (IL-6) is an inflammatory survival cytokine known to induce prolonged activation of STAT3 via association with the IL-6 receptor.

STUDY DESIGN, SIZE, DURATION

Cross-sectional measurements of STAT3 and HIF1A protein levels in eutopic endometrium from women with endometriosis versus those without.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Levels of phospho-STAT3 (pSTAT3) and HIF1A were examined in the endometrium of patients with and without endometriosis as well as in a non-human primate animal model using western blot and immunohistochemical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Levels of pSTAT3 were significantly higher in the eutopic endometrium from women with endometriosis when compared with women without the disease in both the proliferative and secretory phases. HIF1A is known to be stabilized by STAT3 and IL-6. Our immunohistochemistry results show abundant HIF1A expression within the eutopic endometrial epithelial cells of women with endometriosis. Furthermore, pSTAT3 and HIF1A proteins are co-localized in endometriosis. This aberrant activation of pSTAT3 and HIF1A is confirmed by sequential analysis of eutopic endometrium using a baboon animal model of induced endometriosis. Lastly, we confirmed this IL-6 induction of both STAT3 phosphorylation and HIF1A mRNA expression in Ishikawa human endometrial adenocarcinoma cell line.

LIMITATIONS, REASONS FOR CAUTION

Ishikawa cancer cell line was used to study a benign disease. The peritoneal fluid contains various inflammatory cytokines in addition to IL-6 and so it is possible that other cytokines may affect the activity and expression of STAT3 signaling molecules.

WIDER IMPLICATIONS OF THE FINDINGS

Our results imply that aberrant activation of STAT3 signaling plays an important role in the pathogenesis of endometriosis. Our findings could progress in our understanding of the etiology and pathophysiology of endometriosis and potential therapeutic interventions by targeted pharmacological.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIH R01 HD067721 (to S.L.Y and B.A.L) and NIH R01 HD057873 and American Cancer Society Research Grant RSG-12-084-01-TBG (to J.-W.J.). There are no conflicts of interest.

Decreased Notch pathway signaling in the endometrium of women with endometriosis impairs decidualization

CONTEXT

Endometriosis is a common gynecological disease affecting one in 10 women of reproductive age and is a major cause of pelvic pain and impaired fertility. Endometrial stromal cells of women with endometriosis exhibit a reduced response to in vitro decidualization. NOTCH1 is critical for decidualization of both mouse and human uterine stromal cells.

OBJECTIVE

This study aimed to determine whether decidualization failure in women with endometriosis is a consequence of impaired Notch signaling.

SETTING AND DESIGN

We investigated expression levels of Notch signaling components in the endometrium of women and baboons with or without endometriosis. We identified NOTCH1-regulated genes during decidualization of human uterine fibroblast (HuF) cells by microarray and quantified their expression levels in in vitro-decidualized endometrial stromal cells isolated from women with or without endometriosis.

RESULTS

Notch signaling receptors NOTCH1 and NOTCH4, ligands JAGGED2 and DLL4, as well as direct target genes HES5 and HEY1 were decreased in the eutopic endometrium of women and baboons with endometriosis. Notch signaling was decreased in stromal cells isolated from women with endometriosis, which was associated with impaired in vitro decidualization. Genes that were down-regulated by NOTCH1 silencing in decidualized HuF cells were also decreased in decidualized endometrial stromal cells of women with endometriosis. FOXO1 acts as a downstream target of Notch signaling and endometriosis is associated with decreased expression of NOTCH1-regulated, FOXO1-responsive genes during decidualization.

CONCLUSIONS

Decreased Notch signaling is associated with endometriosis and contributes to impaired decidualization through the down-regulation of FOXO1.

Mig-6 suppresses endometrial cancer associated with Pten deficiency and ERK activation

PTEN mutations are the most common genetic alterations in endometrial cancer. Loss of PTEN and subsequent AKT activation stimulate estrogen receptor α-dependent pathways that play an important role in endometrial tumorigenesis. The major pathologic phenomenon of endometrial cancer is the loss of ovarian steroid hormone control over uterine epithelial cell proliferation and apoptosis. However, the precise mechanism of PTEN/AKT signaling in endometrial cancer remains poorly understood. The progesterone signaling mediator MIG-6 suppresses estrogen signaling and it has been implicated previously as a tumor suppressor in endometrial cancer. In this study, we show that MIG-6 also acts as a tumor suppressor in endometrial cancers associated with PTEN deficiency. Transgenic mice, where Mig-6 was overexpressed in progesterone receptor-expressing cells, exhibited a relative reduction in uterine tumorigenesis caused by Pten deficiency. ERK1/2 was phosphorylated in uterine tumors and administration of an ERK1/2 inhibitor suppressed cancer progression in PR(cre/+)Pten(f/f) mice. In clinical specimens of endometrial cancer, MIG-6 expression correlated inversely with ERK1/2 phosphorylation during progression. Taken together, our findings suggest that Mig-6 regulates ERK1/2 phosphorylation and that it is crucial for progression of PTEN-mutant endometrial cancers, providing a mechanistic rationale for the evaluation of ERK1/2 inhibitors as a therapeutic treatment in human endometrial cancer.

Amelioration of hypercholesterolemia by an EGFR tyrosine kinase inhibitor in mice with liver-specific knockout of Mig-6

Mitogen-inducible gene 6 (Mig-6) is a negative feedback inhibitor of epidermal growth factor receptor (EGFR) signaling. We previously found that Mig-6 plays a critical role in the regulation of cholesterol homeostasis and in bile acid synthesis. In this study, we investigated the effects of EGFR inhibition to identify a potential new treatment target for hypercholesterolemia. We used a mouse model with conditional ablation of the Mig-6 gene in the liver (Alb^cre/+Mig-6^f/f; Mig-6^d/d) to effectively investigate the role of Mig-6 in the regulation of liver function. Mig-6^d/d mice were treated with either the EGFR inhibitor gefitinib or statin for 6 weeks after administration of a high-fat or standard diet. We then compared lipid profiles and other parameters among each group of mice. After a high-fat diet, Mig-6^d/d mice showed elevated serum levels of total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides and glucose, characteristics resembling hypercholesterolemia in diabetic patients. We observed decreases in serum levels of lipids and glucose in high-fat-diet-fed Mig-6^d/d mice after 6 weeks of treatment with gefitinib or statin. Furthermore gefitinib-treated mice showed significantly greater decreases in serum levels of total, HDL and LDL cholesterol compared with statin-treated mice. Taken together, these results suggest that EGFR inhibition is effective for the treatment of hypercholesterolemia in high-fat-diet-fed Mig-6^d/d mice, and our findings provide new insights into the development of possible treatment targets for hypercholesterolemia via modulation of EGFR inhibition.

Disturbed cartilage and joint homeostasis resulting from a loss of mitogen-inducible gene 6 in a mouse model of joint dysfunction

OBJECTIVE

Mitogen-inducible gene 6 (MIG-6) regulates epidermal growth factor receptor (EGFR) signaling in synovial joint tissues. Whole-body knockout of the Mig6 gene in mice has been shown to induce osteoarthritis and joint degeneration. To evaluate the role of chondrocytes in this process, Mig6 was conditionally deleted from Col2a1-expressing cell types in the cartilage of mice.

METHODS

Bone and cartilage in the synovial joints of cartilage-specific Mig6-deleted (knockout [KO]) mice and control littermates were compared. Histologic staining and immunohistochemical analyses were used to evaluate joint pathology as well as the expression of key extracellular matrix and regulatory proteins. Calcified tissue in synovial joints was assessed by micro-computed tomography (micro-CT) and whole-skeleton staining.

RESULTS

Formation of long bones was found to be normal in KO animals. Cartilage thickness and proteoglycan staining of articular cartilage in the knee joints of 12-week-old KO mice were increased as compared to controls, with higher cellularity throughout the tissue. Radiopaque chondro-osseous nodules appeared in the knees of KO animals by 12 weeks of age and progressed to calcified bone-like tissue by 36 weeks of age. Nodules were also observed in the spine of 36-week-old animals. Erosion of bone at ligament entheses was evident by 12 weeks of age, by both histologic and micro-CT assessment.

CONCLUSION

MIG-6 expression in chondrocytes is important for the maintenance of cartilage and joint homeostasis. Dysregulation of EGFR signaling in chondrocytes results in anabolic activity in cartilage, but erosion of ligament entheses and the formation of ectopic chondro-osseous nodules severely disturb joint physiology.

Transient anabolic effects accompany epidermal growth factor receptor signal activation in articular cartilage in vivo

Introduction

Signals from the epidermal growth factor receptor (EGFR) have typically been considered to provide catabolic activities in articular cartilage, and accordingly have been suggested to have a causal role in osteoarthritis progression. The aim of this study was to determine in vivo roles for endogenous EGFR signal activation in articular cartilage.

Methods

Transgenic mice with conditional, limb-targeted deletion of the endogenous intracellular EGFR inhibitor Mig-6 were generated using CreLoxP (Mig-6-flox; Prx1Cre) recombination. Histology, histochemical staining and immunohistochemistry were used to confirm activation of EGFR signaling in the articular cartilage and joints, and to analyze phenotypic consequences of Mig-6 loss on articular cartilage morphology, proliferation, expression of progenitor cell markers, presence of chondrocyte hypertrophy and degradation of articular cartilage matrix.

Results

The articular cartilage of Mig-6-conditional knockout (Mig-6-cko) mice was dramatically and significantly thicker than normal articular cartilage at 6 and 12 weeks of age. Mig-6-cko articular cartilage contained a population of chondrocytes in which EGFR signaling was activated, and which were three to four times more proliferative than normal Mig-6-flox articular chondrocytes. These cells expressed high levels of the master chondrogenic regulatory factor Sox9, as well as high levels of putative progenitor cell markers including superficial zone protein (SZP), growth and differentiation factor-5 (GDF-5) and Notch1. Expression levels were also high for activated β-catenin and the transforming growth factor beta (TGF-β) mediators phospho-Smad2/3 (pSmad2/3). Anabolic effects of EGFR activation in articular cartilage were followed by catabolic events, including matrix degradation, as determined by accumulation of aggrecan cleavage fragments, and onset of hypertrophy as determined by type × collagen expression. By 16 weeks of age, the articular cartilage of Mig-6-cko knees was no longer thickened and was degenerating.

Conclusions

These results demonstrate unexpected anabolic effects of EGFR signal activation in articular cartilage, and suggest the hypothesis that these effects may promote the expansion and/or activity of an endogenous EGFR-responsive cell population within the articular cartilage.

Steroid hormone intervenes in the endometrial tumorigenesis of pten ablation

Background:

Endometrial cancer, the most common gynecological cancer, is closely associated with endometrial hyperplasia, unopposed estrogen exposure, and genetic alterations. Phosphatase and tensin homologue (PTEN) is a tumor suppressor genes completely lost or mutated in >50% of primary endometrioid endometrial cancers. Estrogen-dependent endometrioid carcinoma is the most common type of endometrial cancer. Progesterone is a hormone that antagonizes the growth-promoting properties of estrogen in the uterus. Progestin is used as a conservative endocrine treatment of early endometrial cancer in order to preserve fertility as well as a palliative measure for advanced-stage patients. Progesterone therapy has been shown to be effective in preventing endometrial cancer as well as controlling growth of the endometrium. However, the effectiveness of progestin for women with endometrial cancer is less clear.

Methods:

In order to understand the effect of steroid hormone on endometrial cancer progression, we used a mouse endometrial cancer model with conditional loss of Pten in the mouse uterus (PR^cre/+Pten^f/f, Pten^d/d). To assess the effect of steroid hormones, ovariectomized Pten^f/f and Pten^d/d mice were treated with estrogen or progesterone over a period of three month.

Results:

Uterine weight gain was significantly decreased in ovariectomized PR^cre/+Pten^f/f mice compared to intact PR^cre/+Pten^f/f mice. Ovariectomized PR^cre/+Pten^f/f mice treated with P4 or vehicle also exhibited decreased uterine cancer size compared with intact PR^cre/+Pten^f/f mice. Proliferation of ovariectomized PR^cre/+Pten^f/f mice treated with P4 is highly decreased compared to other groups. The levels of stromal progesterone receptor were highly increased in ovariectomized PR^cre/+Pten^f/f mice treated with P4 which resulted in decreased epithelial proliferation.

Conclusions:

These results suggest that P4 treatment significantly reduces tumor mass but does not affect cancer progression in PR^cre/+Pten^f/f mice.

Abstract 94: The role of Pik3ca in uterine gland morphogenesis and fertility in mice

Pik3ca mutations are frequently observed in endometrial carcinomas. Inappropriate activation of PI3Kα-mediated signaling results in increased AKT-dependent or AKT-independent signaling. The PI3K/AKT signaling pathway plays a critical role in the maintenance of equilibrium between cell survival and apoptosis. In order to investigate the role of Pik3ca in uterine function and tumorigenesis, we generated a mouse model in which Pik3ca gene expression is ablated specifically in the PR-expressing cells (PRcre/+ Pik3caf/f). Ablation of Pik3ca was confirmed by real time PCR, western blot, and immunohistochemical analysis of the uteri. PRcre/+ Pik3caf/f mice were subfertile due to defective uterine development. PRcre/+ Pik3caf/f mice showed significantly decreased uterine weight compared Pik3caf/f mice at 2 months of age. Interestingly, PRcre/+ Pik3caf/f mice exhibited a defect of endometrial gland development. Number of glandular epithelia were significantly decreased in PRcre/+ Pik3caf/f mice compared to control Pik3caf/f mice. The expression of Foxa2, a specific glandular epithelial marker, was significantly decreased in PRcre/+ Pik3caf/f mice and apoptosis was significantly increased in the luminal epithelium of PRcre/+ Pik3caf/f mice. These results indicate that Pik3ca plays a role in female fertility and uterine development.

(This work was supported by NIH U54 HD007495 to J.P.L, Basic Science Research Program (2010-0009047) funded by the MEST, Korea to U-H.H., and NIH R01 HD057873 and American Cancer Society Research Grant RSG-12-084-01-TBG to J.W.J.)

Citation Format: Heesung Shin, Tae Hoon Kim, Jung-Yoon Yoo, Jean J. Zhao, John P. Lydon, Un-Hwan Ha, Jae-Wook Jeong. The role of Pik3ca in uterine gland morphogenesis and fertility in mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 94. doi:10.1158/1538-7445.AM2014-94

Abstract 3473: Identification of progesterone-dependent genes regulated by ablation of mitogen-inducible gene-6 (Mig-6) in the murine uterus

Mitogen-inducible gene-6 (Mig-6) is an important mediator of progesterone signaling to inhibit estrogen signaling in the uterus. Ablation of Mig-6 in the murine uterus leads to the development of endometrial hyperplasia and estrogen-induced endometrial cancer. Although Mig-6 is an important tumor suppressor in endometrial cancer, relatively little is known about the molecular mechanisms of Mig-6 in endometrial cancer. To identify the molecular pathways regulated by Mig-6 in a steroid-hormone dependent manner, we performed microarray analysis on the uterus of ovariectomized PRcre/+Mig-6f/f (Mig-6d/d) mice treated with progesterone for 6 hours. In the analysis of GeneChip® Mouse Genome 430 2.0 Array, 2,034 genes, 1,062 genes were up-regulated and 972 genes were down-regulated, were altered by P4 treatment. To determine which pathways are regulated by P4 treatment, we performed pathway analysis using Ingenuity Systems Software. Genes that involved in Estrogen Receptor, IGF-1, PI3K/AKT, JAK/Stat, ERK/MAPK, ILK, p53, PTEN, and Wnt/β-catenin signaling were found to be P4 response. In addition, genes that regulated the molecular mechanisms of cancer were disproportionated. And in microarray, 2,236 genes, 1,883 genes were up-regulated and 356 genes were down-regulated, were regulated by Mig-6 ablation on P4 treatment. Genes involved in ILK, p53, PTEN, PI3K/AKT, and Wnt/β-catenin signaling were found to be deregulated upon Mig-6 ablation on P4 response. Furthermore 324 genes of the 2,034 genes were regulated by P4 treatment were dys-regulated in Mig-6d/d mice treated with P4 compared to Mig-6f/f control mice. These results showed that gene expression pattern was altered by the deletion of Mig-6 and the change of these genes was dependent on P4 in uterus. Thus the further investigation should be completed to identify molecules associated with Mig-6 and the identification of relation between these responsive genes will contribute to define the molecular pathways regulated by Mig-6 in uterine biology.

(This work was supported by NIH, R01 HD057873 and American Cancer Society Research Grant, RSG-12-084-01-TBG to J.W.J.)

Citation Format: Tae Hoon Kim, Jung-Yoon Yoo, Jae-Wook Jeong. Identification of progesterone-dependent genes regulated by ablation of mitogen-inducible gene-6 (Mig-6) in the murine uterus. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3473. doi:10.1158/1538-7445.AM2014-3473

Abstract 60: Mig-6 suppresses development and progression of endometrial cancer by inhibiting ERK2 phosphorylation

Endometrial cancer is the most common cancer of the female reproductive system. PTEN is mutated or absent in more than half of human endometrial cancers. The major pathologic phenomenon of endometrial cancer is the loss of ovarian steroid hormone control over uterine epithelial cell proliferation and apoptosis. Mig-6 suppresses estrogen signaling. Here, we show the significance of MIG-6 in human endometrial cancer through sample analysis, where MIG-6 expression is inversely associated with ERK phosphorylation; this relationship is tightly correlated with endometrial cancer progression. To determine the tumor suppressor function of Mig-6 in the development of endometrial cancer, we generated Mig-6 conditional overexpression mice (R26Mig-6LSL). To assess the effects of Mig-6 on the PTEN/PI3K/AKT signaling pathway in uterine tumorigenesis, mice with Pten floxed (Ptenf/f) and R26Mig-6LSL were bred to the PRCre mouse model to generate overexpression of Mig-6 and ablation of Pten in the uterus (PRcre/+ R26Mig-6LSL Ptenf/f). PRcre/+ R26Mig-6LSL Ptenf/f showed significantly increased survival time and uterine weight compared to PRcre/+ Ptenf/f mice. Gross morphology and histological analysis displayed dramatically suppressed development of endometrial cancer in double mutant mice compared to ablation of Pten alone. Immunohistochemical analysis showed significantly increased apoptosis and decreased proliferation in epithelial cells of PRcre/+ R26Mig-6LSL Ptenf/f mice compared to PRcre/+ Ptenf/f mice. Interestingly, the expression of pERK1/2 was significantly decreased in PRcre/+ R26Mig-6LSL Ptenf/f mice compared to PRcre/+ Ptenf/f mice. To examine whether inhibition of ERK phosphorylation suppresses tumor progression in endometrial cancer, PRcre/+Ptenf/f mice were treated with U0126, an effective inhibitor of MAPK/ERK kinase. PRcre/+Ptenf/f mice treated with U0126 exhibited a significant reduction in uterine weight. Histopathological analysis of the entire animal cohort showed that inhibition of ERK phosphorylation suppressed endometrial cancer progression in PRcre/+ Ptenf/f mice, as reflected by the arrest of tumors at the hyperplastic or normal stage, whereas tumors from PRcre/+Ptenf/f mice treated with vehicle advanced to endometrial cancer. These results demonstrate that activation of ERK signaling is critical for endometrial cancer development and progression in Pten mutation. Our findings highlight a crucial tumor suppressor role for MIG-6 in progression of PTEN-null endometrial cancer by inhibiting ERK phosphorylation. As MIG-6 is a mediator of progesterone signaling, the activity of which can suppress unopposed-estrogen signaling, our studies provide a potential new drug target for the intervention of metastatic human endometrial cancer.

(This work was supported by NIH, U54 HD007495 to J.P.L, NIH, R01 HD057873 and American Cancer Society Research Grant, RSG-12-084-01-TBG to J.W.J.)

Citation Format: Jung-Yoon Yoo, Tae Hoon Kim, Hong Im Kim, Jane Li, Gordon B. Mills, Russell R. Broaddus, John P. Lydon, Ho-Geun Yoon, Jae-Wook Jeong. Mig-6 suppresses development and progression of endometrial cancer by inhibiting ERK2 phosphorylation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 60. doi:10.1158/1538-7445.AM2014-60

The co-injection of somatic cells with embryonic stem cells affects teratoma formation and the properties of teratoma-derived stem cell-like cells

The aim of this study was to assess the biological reactions triggered by stem cell transplantation related to phenotypic alteration, host-to-cell response, chromosomal stability, transcriptional alteration, and stem cell-like cell re-expansion. B6CBAF1 mouse embryonic stem cells (ESCs) were injected subcutaneously into homologous or heterologous (B6D2F1) recipients, and heterologous injections were performed with or without co-injection of B6D2F1 fetal fibroblasts. All homologous injections resulted in teratoma formation, whereas a sharp decrease in formation was detected after heterologous injection (100 vs. 14%; p<0.05). The co-injection of somatic cells in heterologous injections enhanced teratoma formation significantly (14 vs. 75%; p<0.05). Next, ESC-like cell colonies with the same genotype as parental ESCs were formed by culturing teratoma-dissociated cells. Compared with parental ESCs, teratoma-derived ESC-like cells exhibited significantly increased aneuploidy, regardless of homologous or heterologous injections. Repopulation of the parental ESCs was the main factor that induced chromosomal instability, whereas the co-injection of somatic cells did not restore chromosomal normality. Different genes were expressed in the parental ESCs and teratoma-derived ESC-like cells; the difference was larger with parental vs. heterologous than parental vs. homologous co-injections. The co-injection of somatic cells decreased this difference further. In conclusion, the host-to-cell interactions triggered by ESC transplantation could be modulated by co-injection with somatic cells. A mouse model using homologous or heterologous transplantation of stem cells could help monitor cell adaptability and gene expression after injection.

The LIF-mediated molecular signature regulating murine embryo implantation

The establishment of a receptive uterus is the prime requirement for embryo implantation. In mice, the E2-induced cytokine leukemia inhibitory factor (LIF) is essential in switching the uterine luminal epithelium (LE) from a nonreceptive to a receptive state. Here we define the LIF-mediated switch using array analysis and informatics to identify LIF-induced changes in gene expression and annotated signaling pathways specific to the LE. We compare gene expression profiles at 0, 1, 3, and 6 h, following LIF treatment. During the first hour, the JAK-STAT signaling pathway is activated and the expression of 54 genes declines, primarily affecting LE cytoskeletal and chromatin organization as well as a transient reduction in the progesterone, TGFbetaR1, and ACVR1 receptors. Simultaneously 256 genes increase expression, of which 42 are transcription factors, including Sox, Kfl, Hes, Hey, and Hox families. Within 3 h, the expression of 3987 genes belonging to more than 25 biological process pathways was altered. We confirmed the mRNA and protein distribution of key genes from 10 pathways, including the Igf-1, Vegf, Toll-like receptors, actin cytoskeleton, ephrin, integrins, TGFbeta, Wnt, and Notch pathways. These data identify novel LIF-activated pathways in the LE and define the molecular basis between the refractory and receptive uterine phases. More broadly, these findings highlight the staggering capacity of a single cytokine to induce a dynamic and complex network of changes in a simple epithelium essential to mammalian reproduction and provide a basis for identifying new routes to regulating female reproduction.

CRISPLD2 is a target of progesterone receptor and its expression is decreased in women with endometriosis

Endometriosis, defined as the presence of endometrial cells outside of the uterine cavity, is a major cause of infertility and pelvic pain, afflicting more than 10% of reproductive age women. Endometriosis is a chronic inflammatory disease and lipopolysaccharide promotes the proliferation and invasion of endometriotic stromal cells. Cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) has high affinity for lipopolysaccharide and plays a critical role in defense against endotoxin shock. However, the function of CRISPLD2 has not been studied in endometriosis and uterine biology. Herein, we examined the expression of CRISPLD2 in endometrium from patients with and without endometriosis using immunohistochemistry. The expression of CRISPLD2 was higher in the secretory phase in human menstrual cycle compared to proliferative phase. The expression of CRISPLD2 was significantly decreased in the endometrium of women with endometriosis in the early secretory phase compared to women without endometriosis. The increase of CRISPLD2 expression at the early secretory and dysregulation of its expression in endometriosis suggest progesterone (P4) regulation of CRISPLD2. To investigate whether CRISPLD2 is regulated by P4, we examined the expression of the CRISPLD2 in the uteri of wild-type and progesterone receptor knock out (PRKO) mice. The expression of CRISPLD2 was significantly increased after P4 treatment in the wild-type mice. However, CRISPLD2 expression was significantly decreased in the (PRKO) mice treated with P4. During early pregnancy, the expression of CRISPLD2 was increased in decidua of implantation and post-implantation stages. CRISPLD2 levels were also increased in cultured human endometrial stromal cells during in vitro decidualization. These results suggest that the CRISPLD2 is a target of the progesterone receptor and may play an important role in pathogenesis of endometriosis.