GPER Overexpression in Cervical Cancer Versus Premalignant Lesions: Its Activation Induces Different Forms of Cell Death.

BACKGROUND: The effect of estrogen has been traditionally studied through the modulation of its alpha and beta nuclear receptors; however, the G Protein-Coupled Estrogen Receptor (GPER) has been recently involved in the pathology of numerous tumors. Although the study of GPER in cervical cancer has begun, its contribution still remains to be completely evaluated. OBJECTIVE: The purpose of this work was to determine the expression of this receptor in different degrees of cervical lesions and whether the stimulation with its specific agonist (G-1) modulated mechanisms of cell survival or cell death in cervical cancer cells. METHODS: Sections of 44 formalin-fixed paraffin-embedded blocks from patients were analyzed by automated immunohistochemistry. After the stimulation with G-1, proliferation was evaluated by the xCELLigence technology, the integrity of the mitochondrial membrane permeability by MitoCaptureTM fluorescence staining, apoptosis by flow cytometry, and senescence by the senescence-associated ß-galactosidase kit. RESULTS: GPER was widely expressed in cervical cancer but not in its precursor lesions. The staining was predominantly cytoplasmic, although it was also important in the nucleus of the epithelial cells. G-1 inhibited proliferation, decreased the mitochondrial permeability, and increased the percentage of apoptosis in SiHa, HeLa, and C-33A. Only in C-33A, an increase of the cells in necrosis was observed, whereas SiHa was the only cell line in which senescence was evidenced. CONCLUSION: GPER is a receptor associated with cervical cancer that inhibits the growth and induces different mechanisms of death in cells derived from uterine cervical cancer. It suggests that GPER can be considered a pharmacological target that prevents the development of cervical carcinogenesis.

Effects of 60 kDa prolactin and estradiol on metabolism and cell survival in cervical cancer: Co­expression of their hormonal receptors during cancer progression.

Estrogens and estrogen receptors (ERs), such as ERα and ERß, prolactin (PRL) and prolactin receptor (PRLR) have been reported to be involved in the physiopathology of uterine cervical cancer (UCC). The 60 kDa PRL is an isoform of PRL, which is produced by UCC­derived cells. The present study aimed to evaluate the expression of hormonal receptors in different degrees of cervical lesions, and to determine whether 60 kDa PRL and 17ß­estradiol (E2) modulated cell survival and metabolism in UCC cells, and in HaCaT cells transduced with human papillomavirus (HPV) 16 and 18 E6/E7 oncogenes. ERα, ERß, PRLR, Ki67 and B­cell lymphoma 2 expression levels were analyzed in biopsies of precursor lesions and UCC using immunohistochemistry. In addition, HeLa, SiHa and C33A cells, and transduced HaCaT cells, were stimulated with 60 kDa PRL, E2 or a combination of both. Proliferation was evaluated using the xCELLigence platform, apoptosis was analyzed by flow cytometry and cell metabolism was determined using the MTT assay. The results revealed that ERα, ERß, PRLR and Ki67 expression levels were increased during the progression of cancer. In vitro, 60 kDa PRL alone significantly increased proliferation of SiHa cells. Furthermore, E2 alone or in combination with 60 kDa PRL increased the sensitivity of SiHa cells to cisplatin and increased the percentage of apoptosis; in HaCaT cells, these treatment strategies had the opposite effect on cisplatin sensitivity. Treatment with E2 increased mitochondrial activity in HeLa and SiHa cells, and in HaCaT cells transduced with HPV 16 E6/E7 and HPV 18 E6 oncogenes. PRL had a similar effect on HeLa cells, and on HaCaT cells transduced with HPV 18 E6 and HPV 16 E7. The co­expression of these receptors demonstrated the hormonal dependence of UCC. In addition, E2 and the 60 kDa PRL significantly impacted the metabolism, but not the survival, of cells.