Lankai Guo

Prolonging the female reproductive lifespan and improving egg quality with dietary omega-3 fatty acids.

Women approaching advanced maternal age have extremely poor outcomes with both natural and assisted fertility. Moreover, the incidence of chromosomal abnormalities and birth defects increases with age. As of yet, there is no effective and practical strategy for delaying ovarian aging or improving oocyte quality. We demonstrate that the lifelong consumption of a diet rich in omega‐3 fatty acids prolongs murine reproductive function into advanced maternal age, while a diet rich in omega‐6 fatty acids is associated with very poor reproductive success at advanced maternal age. Furthermore, even short‐term dietary treatment with a diet rich in omega‐3 fatty acids initiated at the time of the normal age‐related rapid decline in murine reproductive function is associated with improved oocyte quality, while short‐term dietary treatment with omega‐6 fatty acids results in very poor oocyte quality. Thus, omega‐3 fatty acids may provide an effective and practical avenue for delaying ovarian aging and improving oocyte quality at advanced maternal age.

Inhibitors of SCF-Skp2/Cks1 E3 Ligase Block Estrogen-Induced Growth Stimulation and Degradation of Nuclear p27kip1: Therapeutic Potential for Endometrial Cancer

In many human cancers, the tumor suppressor, p27(kip1) (p27), a cyclin-dependent kinase inhibitor critical to cell cycle arrest, undergoes perpetual ubiquitin-mediated proteasomal degradation by the E3 ligase complex SCF-Skp2/Cks1 and/or cytoplasmic mislocalization. Lack of nuclear p27 causes aberrant cell cycle progression, and cytoplasmic p27 mediates cell migration/metastasis. We previously showed that mitogenic 17-β-estradiol (E2) induces degradation of p27 by the E3 ligase Skp1-Cullin1-F-Box- S phase kinase-associated protein2/cyclin dependent kinase regulatory subunit 1 in primary endometrial epithelial cells and endometrial carcinoma (ECA) cell lines, suggesting a pathogenic mechanism for type I ECA, an E2-induced cancer. The current studies show that treatment of endometrial carcinoma cells-1 (ECC-1) with small molecule inhibitors of Skp2/Cks1 E3 ligase activity (Skp2E3LIs) stabilizes p27 in the nucleus, decreases p27 in the cytoplasm, and prevents E2-induced proliferation and degradation of p27 in endometrial carcinoma cells-1 and primary ECA cells. Furthermore, Skp2E3LIs increase p27 half-life by 6 hours, inhibit cell proliferation (IC50, 14.3μM), block retinoblastoma protein (pRB) phosphorylation, induce G1 phase block, and are not cytotoxic. Similarly, using super resolution fluorescence localization microscopy and quantification, Skp2E3LIs increase p27 protein in the nucleus by 1.8-fold. In vivo, injection of Skp2E3LIs significantly increases nuclear p27 and reduces proliferation of endometrial epithelial cells by 42%-62% in ovariectomized E2-primed mice. Skp2E3LIs are specific inhibitors of proteolytic degradation that pharmacologically target the binding interaction between the E3 ligase, SCF-Skp2/Cks1, and p27 to stabilize nuclear p27 and prevent cell cycle progression. These targeted inhibitors have the potential to be an important therapeutic advance over general proteasome inhibitors for cancers characterized by SCF-Skp2/Cks1-mediated destruction of nuclear p27.

Cables1 protects p63 from proteasomal degradation to ensure deletion of cells after genotoxic stress

The p63 gene product regulates epithelial morphogenesis and female germline integrity. In this study, we show that cyclin‐dependent kinase 5 and Abl enzyme substrate 1 (Cables1) interacts with the trans‐activating (TA) p63α isoform to protect it from proteasomal degradation. Using the female germline of Cables1‐null mice as an in vivo model, we demonstrate further that oocytes lacking Cables1 exhibit lower basal levels of TAp63α and reduced accumulation of phosphorylated TAp63α in response to genotoxic stress. This in turn enhances the survival of these cells after ionizing radiation exposure. Thus, Cables1 modulates p63 protein stability and function during genotoxic stress.

Upregulation of MUC4 in cervical squamous cell carcinoma: pathologic significance.

MUC4 is a transmembrane glycoprotein more highly expressed in cervical dysplasia than benign cervical epithelium. We sought to determine whether MUC4 expression differs between benign and malignant cervical tissue. Fifty-eight patients with benign, dysplastic, or malignant cervical pathology were identified retrospectively, and representative sections were stained with a mouse monoclonal anti-MUC4 antibody. Semiquantitative analysis was performed on benign, dysplastic, and malignant regions by scoring staining intensity (0: negative, 1: weak, 2: moderate, and 3: strong) and distribution (focal <10%, multifocal=10%–60%, diffuse ≥60%). In samples with benign glycogenated squamous epithelium, only the parabasal cells had MUC4 staining, and 48.5% had an intensity of 2 or 3. All samples with immature squamous metaplasia were positive through the entire epithelial thickness. Cervical intraepithelial neoplasia (CIN) 1 samples had variable staining with an intensity similar to glycogenated squamous epithelium but distribution similar to squamous metaplasia. All CIN 3 (n=21) and invasive squamous cell carcinomas (n=17) had increased MUC4 staining intensity (P<0.001 and P<0.001) and increased diffuse staining (P<0.001 and P<0.001) compared with the limited staining in glycogenated squamous epithelium. In contrast, no differences in staining were observed between benign endocervical glands, adenocarcinoma in situ, and invasive adenocarcinoma. These expression patterns suggest that MUC4 is a lineage marker in benign cervical tissue that may have aberrant expression in squamous dysplasia and carcinoma. Further studies may elucidate the role of MUC4 in the development of squamous cell cervical cancer.

Metformin Therapy in a Hyperandrogenic Anovulatory Mutant Murine Model with Polycystic Ovarian Syndrome Characteristics Improves Oocyte Maturity during Superovulation

BackgroundMetformin, an oral biguanide traditionally used for the treatment of type 2 diabetes, is widely used for the management of polycystic ovary syndrome (PCOS)-related anovulation. Because of the significant prevalence of insulin resistance and glucose intolerance in PCOS patients, and their putative role in ovulatory dysfunction, the use of metformin was touted as a means to improve ovulatory function and reproductive outcomes in PCOS patients. To date, there has been inconsistent evidence to demonstrate a favorable effect of metformin on oocyte quality and competence in women with PCOS. Given the heterogeneous nature of this disorder, we hypothesized that metformin may be beneficial in mice with aberrant metabolic characteristics similar to a significant number of PCOS patients. The aim of this study was to gain insight into the in vitro and in vivo effects of metformin on oocyte development and ovulatory function.MethodsWe utilized metformin treatment in the transgenic ob/ob and db/db mutant murine models which demonstrate metabolic and reproductive characteristics similar to women with PCOS. Results: Metformin did not improve in vitro oocyte maturation nor did it have an appreciable effect on in vitro granulosa cell luteinization ( progesterone production) in any genotype studied. Although both mutant strains have evidence of hyperandrogenemia, anovulation, and hyperinsulinemia, only db/db mice treated with metformin had a greater number of mature oocytes and total overall oocytes compared to control. There was no observed impact on body mass, or serum glucose and androgens in any genotype.ConclusionsOur data provide evidence to suggest that metformin may optimize ovulatory performance in mice with a specific reproductive and metabolic phenotype shared by women with PCOS. The only obvious difference between the mutant murine models is that the db/db mice have elevated leptin levels raising the questions of whether their response to metformin is related to elevated leptin levels and/or if a subset of PCOS women with hyperleptinemia may be responsive to metformin therapy. Further study is needed to better define a subset of women with PCOS that may be responsive to metformin.

Mechanisms of Cables 1 gene inactivation in human ovarian cancer development

Cables 1, a cyclin-dependent kinase binding protein, is primarily involved in cell cycle regulation. Loss of nuclear Cables 1 expression is observed in human colon, lung and endometrial cancers. We previously reported that loss of nuclear Cables 1 expression was also observed with high frequency in a limited sample set of human ovarian carcinomas, although the mechanisms underlying loss of nuclear Cables 1 expression remained unknown. Our present objective was to examine Cables 1 expression in ovarian cancer in greater detail, and determine the predominant mechanisms of Cables 1 loss. We assessed potential genetic and epigenetic modifications of the Cables 1 locus through analyses of mutation, polymorphisms, loss of heterozygosity and DNA methylation. We observed a marked loss of nuclear Cables 1 expression in serous and endometrioid ovarian carcinomas that correlated with decreased Cables 1 mRNA levels. Although we detected no Cables 1 mutations, there was evidence of LOH at the Cables 1 locus and epigenetic modification of the Cables 1 promoter region in a subset of ovarian carcinomas and established cancer cell lines. From a functional perspective, over-expression of Cables 1 induced apoptosis, whereas, knockdown of Cables 1 negated this effect. Together these findings suggest that multiple mechanisms underlie the loss of Cables 1 expression in ovarian cancer cells, supporting the hypothesis that Cables 1 is a tumor suppressor in human ovarian cancer.

Identification of LMX1B as a novel oncogene in human ovarian cancer

Ovarian cancers are thought to result from the accumulation of multiple genetic aberrations that transform ovarian and/or fallopian tube surface epithelial cells, allowing for their abnormal growth, proliferation and metastasis. In the report presented here, we carried out genome-wide copy-number analysis using comparative genomic hybridization on a panel of mouse ovarian cancer (OVCA) cell lines previously established in our laboratory. We identified a recurrent focal amplification on mouse chromosomal region 2qB, which contains the LIM-homeodomain-containing transcription factor 1B (Lmx1b) gene. LMX1B is not expressed in normal human ovary, but is expressed in many human OVCA cell lines and primary tumors. High expression of LMX1B correlates with poor outcome. To clarify the role of LMX1B in ovarian carcinogenesis, we transduced LMX1B into a panel of mouse and human OVCA cell lines and demonstrated that LMX1B strongly promotes migration of cancer cells in culture and promotes xenograft growth in nude mice. Conversely, knockdown of LMX1B in a human cell line with endogenous high expression of LMX1B inhibits cell migration in vitro and tumor growth in vivo. Microarray analysis of cells overexpressing LMX1B identified the nuclear factor (NF)-κB pathway as a potential mediator of tumor progression and subsequent treatment of NFκB inhibitor decreased the migratory capacity of these cells. Thus, our data demonstrate that LMX1B is a novel oncogene in OVCA pathogenesis.

MicroRNA-15b regulates reversion-inducing cysteine-rich protein with Kazal motifs (RECK) expression in human uterine leiomyoma

BackgroundHuman uterine leiomyoma (fibroids; LYO) are the most common benign neoplasms in reproductive-aged women. Dysregulated extracellular matrix and irregular LYO reversion-inducing cysteine-rich protein with Kazal motifs (RECK) expression are thought to be mediated by aberrant microRNA (miR) expression. The relationship of miR-15b and RECK expression in LYO has not been studied.MethodsThe expression levels of miR-15b and RECK were determined by quantitative RT-PCR, Western blot, and immunohistochemistry in cultures derived from commercial primary leiomyoma (cpLYO) and myometrial (cpMYO) cell lines and leiomyoma (pLYO) and myometrium (pMYO) tissue from surgical samples respectively. The relationship between miR-15b and RECK expression in cpLYO and pLYO (compared to their respective myometrial controls) was evaluated following transfection of cell cultures with either miR-15b mimic or inhibitor.ResultsElevated levels of miR-15b were observed in cpLYO (2.82-fold; p = 0.04) and pLYO cell (1.30-fold; p = 0.0001) cultures respectively compared to corresponding MYO cell controls. Following transfection with miR-15b mimic, cpLYO cells (0.62-fold; p < 0.0001) and pLYO cells (0.68-fold; p < 0.0001) demonstrated reduced RECK protein expression. Following transfection with miR-15b inhibitor, cpLYO cells (1.20-fold; p < 0.0001) and pLYO cells (1.31-fold; p = 0.0007) demonstrated elevated RECK protein expression. RECK protein expression was reduced in pLYO tissues (0.73-fold; p < 0.0001) and pLYO (0.47-fold; p = 0.047) cells when compared to the corresponding MYO tissue controls.ConclusionOur findings suggest that miR-15b negatively regulates RECK expression in LYO, and increased miR-15b and decreased RECK expression may contribute to the pathobiology of LYO. The functional significance of miR-15b and RECK expression warrants further investigation as potential therapeutic targets for the treatment of human LYO.

Effect of sunitinib on functional reproductive outcome in a rabbit model.

OBJECTIVE To determine the effect of sunitinib (Sutent; SU11248; Pfizer), a US Food and Drug Administration-approved receptor tyrosine kinase inhibitor previously shown to reduce de novo pelvic adhesion formation, on reproductive function after surgical uterine abrasion in a rabbit model. DESIGN Randomized placebo-controlled study. SETTING Large animal facility within an academic hospital. ANIMAL(S) Thirty New Zealand White adult female rabbits (2.2-3.0 kg). INTERVENTION(S) Administration of 11 doses (one preoperative and 10 postoperative) of oral sunitinib (10 mg/kg/d) or placebo. MAIN OUTCOME MEASURE(S) Effect of short-term postoperative sunitinib administration on reproductive function after surgical uterine abrasion. RESULT(S) All animals were impregnated and survived until designated euthanasia. Sunitinib-treated animals had a larger average litter size (7.7 ± 1.9 vs. 5.6 ± 2.7 kits) and offspring viability (7.1 ± 2.7 vs. 3.5 ± 3.2 kits) compared with placebo-treated animals. There was no difference in gestational length or aberration in the maintenance of fertility. There were no gross abnormalities, detectable birth defects, or growth disparity in offspring from sunitinib versus placebo-treated mothers. The adhesion burden identified at euthanasia after parturition was lower in sunitinib compared with placebo-treated animals (N = 10/group). CONCLUSION(S) Sunitinib ameliorated adhesion-induced reproductive aberrations after surgical uterine abrasion and may be an efficacious strategy to reduce postoperative pelvic adhesions.

Abstract 1534: Identification of LMX1B as a novel oncogene in human ovarian cancer

Ovarian cancers are thought to result from the accumulation of multiple genetic aberrations that transform ovarian and/or fallopian tube surface epithelial cells, allowing for their abnormal growth, proliferation and metastasis. We carried out genome-wide copy-number analysis using array comparative genomic hybridization on a panel of mouse ovarian cancer (OVCA) cell lines previously established in our laboratory. We identified a recurrent focal amplification on mouse chromosomal region 2qB, which contains the LIM homeodomain containing transcription factor 1B (Lmx1b) gene. LMX1B is not expressed in normal human ovary, but is expressed in many human OVCA cell lines and primary tumors. High expression of LMX1B correlates with poor outcome. To clarify the role of LMX1B in ovarian carcinogenesis, we transduced LMX1B into a panel of mouse and human OVCA cell lines and demonstrated that LMX1B strongly promotes migration of cancer cells in culture and accelerates xenograft growth in nude mice. Conversely, knockdown of LMX1B in a human cell line with endogenous high expression of LMX1B inhibits cell migration in vitro and tumor growth in vivo. Microarray analysis of cells overexpressing LMX1B identified NF-κB pathway as a potential mediator of tumor progression and subsequent treatment of NF-κB inhibitor decreased the migratory capacity of these cells. Thus, our data demonstrate that LMX1B functions as an oncogene in OVCA pathogenesis. Citation Format: Gayatry Mohapatra, Lei He, Lankai Guo, Vinod Vathipadiekal, Petra Sergent, Whitfield Growdon, Bo Rueda, David Engler, Sandra Orsulic, Michael Birrer. Identification of LMX1B as a novel oncogene in human ovarian cancer. [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 1534. doi:10.1158/1538-7445.AM2014-1534