Iris L. Romero

Adipocytes promote ovarian cancer metastasis and provide energy for rapid tumor growth

Intra-abdominal tumors, such as ovarian cancer, have a clear predilection for metastasis to the omentum, an organ primarily composed of adipocytes. Currently, it is unclear why tumor cells preferentially home to and proliferate in the omentum, yet omental metastases typically represent the largest tumor in the abdominal cavities of women with ovarian cancer. We show here that primary human omental adipocytes promote homing, migration and invasion of ovarian cancer cells, and that adipokines including interleukin-8 (IL-8) mediate these activities. Adipocyte–ovarian cancer cell coculture led to the direct transfer of lipids from adipocytes to ovarian cancer cells and promoted in vitro and in vivo tumor growth. Furthermore, coculture induced lipolysis in adipocytes and β-oxidation in cancer cells, suggesting adipocytes act as an energy source for the cancer cells. A protein array identified upregulation of fatty acid–binding protein 4 (FABP4, also known as aP2) in omental metastases as compared to primary ovarian tumors, and FABP4 expression was detected in ovarian cancer cells at the adipocyte-tumor cell interface. FABP4 deficiency substantially impaired metastatic tumor growth in mice, indicating that FABP4 has a key role in ovarian cancer metastasis. These data indicate adipocytes provide fatty acids for rapid tumor growth, identifying lipid metabolism and transport as new targets for the treatment of cancers where adipocytes are a major component of the microenvironment.

CD95 promotes tumour growth

CD95 (also called Fas and APO-1) is a prototypical death receptor that regulates tissue homeostasis mainly in the immune system through the induction of apoptosis. During cancer progression CD95 is frequently downregulated or cells are rendered apoptosis resistant, raising the possibility that loss of CD95 is part of a mechanism for tumour evasion. However, complete loss of CD95 is rarely seen in human cancers and many cancer cells express large quantities of CD95 and are highly sensitive to CD95-mediated apoptosis in vitro. Furthermore, cancer patients frequently have elevated levels of the physiological ligand for CD95, CD95L. These data raise the possibility that CD95 could actually promote the growth of tumours through its non-apoptotic activities. Here we show that cancer cells in general, regardless of their CD95 apoptosis sensitivity, depend on constitutive activity of CD95, stimulated by cancer-produced CD95L, for optimal growth. Consistently, loss of CD95 in mouse models of ovarian cancer and liver cancer reduces cancer incidence as well as the size of the tumours. The tumorigenic activity of CD95 is mediated by a pathway involving JNK and Jun. These results demonstrate that CD95 has a growth-promoting role during tumorigenesis and indicate that efforts to inhibit its activity rather than to enhance it should be considered during cancer therapy.

Adipose tissue and adipocytes support tumorigenesis and metastasis.

Adipose tissue influences tumor development in two major ways. First, obese individuals have a higher risk of developing certain cancers (endometrial, esophageal, and renal cell cancer). However, the risk of developing other cancers (melanoma, rectal, and ovarian) is not altered by body mass. In obesity, hypertrophied adipose tissue depots are characterized by a state of low grade inflammation. In this activated state, adipocytes and inflammatory cells secrete adipokines and cytokines which are known to promote tumor development. In addition, the adipocyte mediated conversion of androgens to estrogen specifically contributes to the development of endometrial cancer, which shows the greatest relative risk (6.3-fold) increase between lean and obese individuals. Second, many tumor types (gastric, breast, colon, renal, and ovarian) grow in the anatomical vicinity of adipose tissue. During their interaction with cancer cells, adipocytes dedifferentiate into pre-adipocytes or are reprogrammed into cancer-associated adipocytes (CAA). CAA secrete adipokines which stimulate the adhesion, migration, and invasion of tumor cells. Cancer cells and CAA also engage in a dynamic exchange of metabolites. Specifically, CAA release fatty acids through lipolysis which are then transferred to cancer cells and used for energy production through β-oxidation. The abundant availability of lipids from adipocytes in the tumor microenvironment, supports tumor progression and uncontrolled growth. Given that adipocytes are a major source of adipokines and energy for the cancer cell, understanding the mechanisms of metabolic symbiosis between cancer cells and adipocytes, should reveal new therapeutic possibilities. This article is part of a Special Issue entitled Lipid Metabolism in Cancer.

Foretinib (GSK1363089), an Orally Available Multikinase Inhibitor of c-Met and VEGFR-2, Blocks Proliferation, Induces Anoikis, and Impairs Ovarian Cancer Metastasis

Purpose: Currently, there are no approved targeted therapies for the treatment of ovarian cancer, despite the fact that it is the most lethal gynecological malignancy. One proposed target is c-Met, which has been shown to be an important prognostic indicator in a number of malignancies, including ovarian cancer. The objective of this study was to determine whether an orally available multikinase inhibitor of c-Met and vascular endothelial growth factor receptor-2 (foretinib, GSK1363089) blocks ovarian cancer growth. Experimental Design: The effect of foretinib was tested in a genetic mouse model of endometrioid ovarian cancer, several ovarian cancer cell lines, and an organotypic 3D model of the human omentum. Results: In the genetic mouse model, treatment with foretinib prevented the progression of primary tumors to invasive adenocarcinoma. Invasion through the basement membrane was completely blocked in treated mice, whereas in control mice, invasive tumors entirely replaced the normal ovary. In 2 xenograft mouse models using human ovarian cancer cell lines, the inhibitor reduced overall tumor burden (86% inhibition, P < 0.0001) and metastasis (67% inhibition, P < 0.0001). The mechanism of inhibition by foretinib involved (a) inhibition of c-Met activation and downstream signaling, (b) reduction of ovarian cancer cell adhesion, (c) a block in migration and invasion, (d) reduced proliferation mediated by a G2–M cell-cycle arrest, and (e) induction of anoikis. Conclusions: This study shows that foretinib blocks tumorigenesis and reduces invasive tumor growth in different models of ovarian cancer by affecting several critical tumor functions. We believe that it provides a rationale for the further clinical development of foretinib for the treatment of ovarian cancer. Clin Cancer Res; 17(12); 4042–51. ©2011 AACR.

Molecular Pathways: Trafficking of Metabolic Resources in the Tumor Microenvironment

A model of tumor metabolism is proposed that describes how the complementary metabolic functions of the local stroma and the tumor cells contribute to cancer progression. Cancer cells alter the metabolism of cancer-associated fibroblasts to obtain lactate and amino acids, which are utilized for energy production, rapid growth, and resistance to chemotherapy drugs. Cancer cells use glutamine supplied by cancer-associated fibroblasts to replenish tricarboxylic acid cycle intermediates and as a nitrogen source for nucleotide synthesis. Moreover, adipocytes in the microenvironment attract cancer cells through the secretion of inflammatory cytokines and proteases. The cancer cells then induce metabolic changes in the adipocytes to acquire free fatty acids that are oxidized by cancer cells to generate energy for proliferation. Increasing knowledge about the metabolic symbiosis within the tumor has led to novel therapeutic strategies designed to restrict metabolic adaptation, including inhibiting lactate transporters and repurposing antidiabetic drugs (thiazolidinediones, metformin). Clin Cancer Res; 21(4); 680–6. ©2015 AACR.

Statin therapy is associated with improved survival in patients with non-serous-papillary epithelial ovarian cancer: a retrospective cohort analysis.

Aim To determine whether statin use is associated with improved epithelial ovarian cancer (OvCa) survival. Methods This is a single-institution retrospective cohort review of patients treated for OvCa between 1992 and 2013. Inclusion criteria were International Federation of Gynecology and Obstetrics (FIGO) stage I–IV OvCa. The primary exposures analyzed were hyperlipidemia and statin use. The primary outcomes were progression-free survival (PFS) and disease-specific survival (DSS). Results 442 patients met inclusion criteria. The cohort was divided into three groups: patients with hyperlipidemia who used statins (n = 68), patients with hyperlipidemia who did not use statins (n = 28), and patients without hyperlipidemia (n = 346). OvCa outcomes were evaluated. When we analyzed the entire cohort, we found no significant differences in PFS or DSS among the groups. The median PFS for hyperlipidemics using statins, hyperlipidemics not using statins, and non-hyperlipidemics was 21.7, 13.6, and 14.7 months, respectively (p = 0.69). Median DSS for hyperlipidemics using statins, hyperlipidemics not using statins, and non-hyperlipidemics was 44.2, 75.7, and 41.5 months, respectively (p = 0.43). These findings did not change after controlling for confounders. However, a secondary analysis revealed that, among patients with non-serous-papillary subtypes of OvCa, statin use was associated with a decrease in hazards of both disease recurrence (adjusted HR = 0.23, p = 0.02) and disease-specific death (adjusted HR = 0.23, p = 0.04). To augment the findings in the retrospective cohort, the histology-specific effects of statins were also evaluated in vitro using proliferation assays. Here, statin treatment of cell lines resulted in a variable level of cytotoxicity. Conclusion Statin use among patients with non-serous-papillary OvCa was associated with improvement in both PFS and DSS.

Effects of Oral Contraceptives or a Gonadotropin-Releasing Hormone Agonist on Ovarian Carcinogenesis in Genetically Engineered Mice

Although epidemiologic evidence for the ability of combined oral contraception (OC) to reduce the risk of ovarian cancer (OvCa) is convincing, the biological mechanisms underlying this effect are largely unknown. We conducted the present study to determine if OC also influences ovarian carcinogenesis in a genetic mouse model and, if so, to investigate the mechanism underlying the protective effect. LSL-K-rasG12D/+PtenloxP/loxP mice were treated with ethinyl estradiol plus norethindrone, contraceptive hormones commonly used in combined OC, or norethindrone alone, or a gonadotropin-releasing hormone agonist. The combined OC had a 29% reduction in mean total tumor weight compared with placebo (epithelial tumor weight, −80%). Norethindrone alone reduced mean total tumor weight by 42% (epithelial tumor weight, −46%), and the gonadotropin-releasing hormone agonist increased mean total tumor weight by 71% (epithelial tumor weight, +150%). Large variations in tumor size affected the P values for these changes, which were not statistically significant. Nonetheless, the OC reductions are consistent with the epidemiologic data indicating a protective effect of OC. Matrix metalloproteinase-2 activity was decreased in association with OC, indicating that OC may affect ovarian carcinogenesis by decreasing proteolytic activity, an important early event in the pathogenesis of OvCa. In contrast, OC increased invasion in a K-ras/Pten OvCa cell line established from the mouse tumors, suggesting that OC hormones, particularly estrogen, may have a detrimental effect after the disease process is under way. Our study results support further investigation of OC effects and mechanisms for OvCa prevention.

Association of Metformin Use with Outcomes in Advanced Endometrial Cancer Treated with Chemotherapy.

There is increasing evidence that metformin, a commonly used treatment for diabetes, might have the potential to be repurposed as an economical and safe cancer therapeutic. The aim of this study was to determine whether stage III-IV or recurrent endometrial cancer patients who are using metformin during treatment with chemotherapy have improved survival. To test this we analyzed a retrospective cohort of subjects at two independent institutions who received chemotherapy for stage III-IV or recurrent endometrial cancer from 1992 to 2011. Diagnosis of diabetes, metformin use, demographics, endometrial cancer clinico-pathologic parameters, and survival duration were abstracted. The primary outcome was overall survival. The final cohort included 349 patients, 31 (8.9%) had diabetes and used metformin, 28 (8.0%) had diabetes but did not use metformin, and 291 (83.4%) did not have diabetes. The results demonstrate that the median overall survival was 45.6 months for patients with diabetes who used metformin compared to 12.5 months for patients with diabetes who did not use metformin and 28.5 months for patients without diabetes (log-rank test comparing the three groups P = 0.006). In a model adjusted for confounders, the difference in survival between the three groups remained statistically significant (P = 0.023). The improvement in survival among metformin users was not explained by better baseline health status or more aggressive use of chemotherapy. Overall, the findings in this retrospective cohort of endometrial cancer patients with stage III-IV or recurrent disease treated with chemotherapy indicate that patients with diabetes who were concurrently treated with metformin survived longer than patients with diabetes who did not use metformin.

The effects of 17β-estradiol and a selective estrogen receptor modulator, bazedoxifene, on ovarian carcinogenesis

OBJECTIVE To test if estrogen promotes carcinogenesis in vitro and in a genetic mouse model of ovarian cancer and whether its effects can be inhibited by a novel selective estrogen receptor modulator (SERM), bazedoxifene. METHODS Bazedoxifene was synthesized and it was confirmed that the drug abrogated the uterine stimulatory effect of 17β-estradiol in mice. To determine if hormones alter tumorigenesis in vivo LSL-K-ras(G12D/+)Pten(loxP/loxP) mice were treated with vehicle control, 17β-estradiol or bazedoxifene. Hormone receptor status of a cell line established from LSL-K-ras(G12D/+)Pten(loxP/loxP) mouse ovarian tumors was characterized using Western blotting and immunohistochemistry. The cell line was treated with hormones and invasion assays were performed using Boyden chambers and proliferation was assessed using MTT assays. RESULTS In vitro 17β-estradiol increased both the invasion and proliferation of ovarian cancer cells and bazedoxifene reversed these effects. However, in the genetic mouse model neither treatment with 17β-estradiol nor bazedoxifene changed mean tumor burden when compared to treatment with placebo. The mice in all treatment groups had similar tumor incidence, metastatic nodules and ascites. CONCLUSION While 17β-estradiol increases the invasion and proliferation of ovarian cancer cells, these effects do not translate into increased tumor burden in a genetic mouse model of endometrioid ovarian cancer. Likewise, while the SERM reversed the detrimental effects of estrogen in vitro, there was no change in tumor burden in mice treated with bazedoxifene. These findings demonstrate the complex interplay between hormones and ovarian carcinogenesis.

Lesbian Pregnancy: Care and Considerations

&NA; The constructs and the provision of preconception and obstetrical care have historically been based on the assumption of heterosexuality, and have often excluded lesbian women. However, due to significant strides in lesbian, gay, bisexual, transgender, and queer (LGBTQ) civil rights, more lesbian women desire to create and expand their families, and lesbian parented families are increasing. This places obstetrical care providers at the forefront of the movement to build inclusive health care environments. Therefore, it is incumbent upon those of us who work in obstetrics to understand, recognize, and respect the unique cultural considerations that pertain to lesbian women and couples seeking parenthood. This review seeks to provide culturally sensitive guidance on the specific concerns and challenges lesbians face, from preconception care to postpartum care, and briefly addresses legal issues and considerations for the nonbiologic mother. The recommendations outlined here are drawn from studies of the experiences of lesbian women with pregnancy. However, the scientific literature is very limited, and there is a clear need for additional obstetrical research focused on this patient group. As professionals committed to assuring optimal outcomes for all obstetrical patients, it is crucial that we promote the inclusion of sexual minority women in our clinical practices and research endeavors.