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Purpose: The mechanisms underlying the effects of estrogen on endometrial cancer remain undefined. Although the classical mechanism of the action of estrogen involves binding to the estrogen receptors α and β, and transduction of the signal into the cell, G protein-coupled receptor (GPR) 30 has been shown to mediate nongenomic estrogen signaling. The goal of this study was to determine the role of GPR30 signal in the basic process such as invasion and carcinogenesis of endometrial cancer., Methods: We downregulated the expression of GPR30 in endometrial cancer cell line RL95-2 by transfection with shGPR30-pGFP-V-RS, a GPR30 antisense expression vector. The cells were then subjected to an MTT assay and a Transwell(®) migration assay. And an animal model was also used to investigate the influence of downregulation of GPR30 on oncogenesis., Results: Downregulation of GPR30 led to reduced growth and invasion by cells treated with 17β-estradiol. And the capacity of transfected RL95-2 cells to promote tumorigenesis was weakened in vivo., Conclusions: Our data suggest that, for the endometrial cancer cell line RL95-2, GPR30 plays important roles in mediating the proliferative and invasive effects of estrogen and in tumorigenesis.

Objective: The objectives of the study were to evaluate the role of mitogen-activated protein kinase (MAPK) signaling in normal, hyperplastic, and neoplastic endometrium in relation to estrogen receptor (ER) status and to investigate whether 17β-estradiol (E2) and tamoxifen (TAM) mediate the proliferation and apoptosis of endometrial cancer cells through the MAPK pathway., Methods: The expressions of phosphorylated and total extracellular signal-regulated kinases 1/2 (phosphorylated extracellular signal-regulated kinase 1/2 [p-ERK1/2] and total ERK1/2 [t-ERK1/2]) were analyzed with immunohistochemistry in normal, hyperplastic, and neoplastic endometrium. The expression levels of p-ERK1/2 and t-ERK1/2 in RL95-2 and KLE after stimulation by E2, progesterone (P), and TAM were detected by Western blotting. The effects of E2 and TAM in combination with MAPK pathway inhibitors on the growth and apoptosis of endometrial cancer cells were examined by the MTS assay and flow cytometry analysis., Results: The expression level of p-ERK1/2 was significantly associated with the International Federation of Gynecology and Obstetrics stage (P = 0.0072). The ratio of phosphorylated/total ERK1/2 was higher in ER-positive endometrial cancer tissues and cells (P < 0.05). 17β-Estradiol increased ERK1/2 phosphorylation, and TAM decreased ERK1/2 phosphorylation in endometrial cancer cell lines within 30 minutes (P < 0.05). The MEK1/2 inhibitor, U0126, and the stress-activated protein kinase/c-Jun NH2-terminal kinase inhibitor, SP600125, significantly suppressed the proliferation of human endometrial cancer cell lines RL95-2 and KLE induced by E2 (P < 0.05). The level of TAM-induced apoptosis was greater in KLE than in RL95-2 cells, and the p38 cascade was involved in the TAM-induced apoptosis of both cell lines (P < 0.05)., Conclusions: The cross-talk between MAPK signaling and ER status might exert a key role in progression of endometrial cancer. Furthermore, the effects of E2 or TAM on the proliferation or apoptosis of ER-positive and ER-negative endometrial cancer cells were mediated through distinct MAPK pathways. These mechanisms might contribute to ER-specific differences in MAPK activation for molecular-target therapies in endometrial carcinoma.

Objective: The aim of this study was to investigate the expression of kallikrein 4 (KLK4) and the potential signal pathway through which estrogen up-regulates KLK4 in endometrial cancer., Methods: The expression of KLK4 was analyzed in 15 human normal endometrium, 13 hyperplasia endometrium, and 68 endometrioid adenocarcinoma by immunohistochemistry. After exposure to 17beta-estradiol and/or to the mitogen-activated protein kinase (MAPK) inhibitor U0126 and to the PI3K inhibitor LY294002, the expression of KLK4 in the endometrial cancer cell lines KLE and RL95-2 was detected with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot., Results: The expression of KLK4 protein was higher in endometroid endometrial cancer than in hyperplasia or normal endometrium (P < 0.001). Immunohistochemical staining revealed that 92.6% (63/68) of endometrial adenocarcinoma, 61.5% (8/13) of hyperplasia endometrium, and 26.7% (4/15) of normal endometrium were positive for KLK4 protein. The expression of KLK4 was significantly associated with tumor grade (P = 0.004), but not with ER status (P = 0.532). Quantitative reverse transcriptase PCR and Western blot analysis showed that estrogen can up-regulate the expression of KLK4 in endometrial cancer cell lines KLE and RL95-2, and the up-regulation effect of 17beta-estradiol on KLK4 can be inhibited by U0126 in the 2 endometrial cancer cell lines but not by LY294002., Conclusions: Kallikrein 4 is a new nuclear protein, and estrogen up-regulates the expression of KLK4 by activating the MAPK pathway in endometrial cancer cell lines, which may play an important role in the development of endometrial cancer.

The regulatory mechanism of endometrial carcinoma and the signal transduction pathways involved in hormone action are poorly defined. It has become apparent that the G protein-coupled receptor (GPR) 30 mediates the non-genomic signaling of 17beta-estradiol (E2). Here we show that GPR30 is highly expressed in endometrial cancer tissues and cancer cell lines and positively regulates cell proliferation and invasion. GPR30 expression was detected in 50 human endometrial carcinomas. The transcription level of GPR30 was significantly higher in the tissue of endometrial carcinoma than in normal endometrium (P < 0.05). Immunohistochemical assays revealed that the positive expression rate of GPR30 protein in endometrial carcinoma tissue (35/50, 70%) was statistically higher than in normal endometrium tissue (8/30, 26.67%) (chi2 = 14.16, P = 0.0002). GPR30 overexpression was correlated with high-grade endometrial carcinoma. GPR30 expression was also found in two human endometrial cancer cell lines: RL95-2 (estrogen receptor positive) and KLE (estrogen receptor negative). The roles of GPR30 in proliferative and invasive responses to E2 and G1, a non-steroidal GPR30-specific agonist, in RL95-2 and KLE cell lines were then explored. We showed that E2 and G1 could initiate the MAPK/ERK mitogen-activated protein kinase pathway in both cell lines. What's more, E2 and G1 promoted KLE and RL95-2 proliferation and stimulated matrix metalloproteinase production and activity via the GPR30-mediated MEK/ERK mitogen-activated protein kinase pathway, as well as increased interleukin-6 secretion. These findings suggest that GPR30-mediated non-genomic signaling could play an important role in endometrial cancer.

Objective: To study the gene expression profile of different stage endometrial cancer and identify genes related to the progression and metastasis of endometrial cancer., Methods: cDNA microarray was used to analyze the differentially expressed genes between different stage endometrial cancers. The hierarchical cluster analysis was applied to the gene expression profile of 32 endometrial cancers., Results: Twelve differentially expressed genes were identified between different stage endometrial cancers. The conformity rate was 66% between the result of hierarchical cluster analysis and the operative-histological stages of International Federation of Gynecology and Obstetrics (FIGO)., Conclusion: Genes related to the endometrial cancer progression and metastasis can be identified by differential gene expression profile with cDNA microarray and high-risk endometrial cancer may be distinguished before surgery by hierarchical cluster analysis.