The Regulation Of Estrogen Receptor And Mitogen-activated Protein Kinase Signaling In Endometrial Cancer

Endometrial cancer (EC) continues to be the most common malignancy of the female genital tract over the past years. Most of the EC is estrogen-related carcinoma and long-term estrogen stimulation without progesterone counteraction play an important role in the development of EC. Abnormal of the regulation of estrogen, estrogen receptor (ER), and ER related signaling result in the development and progression of EC. Mitogen-activated protein kinase (MAPK) is a key kinase regulating cell proliferation and apoptosis. It has been indicated that MAPK pathway was an important signal pathway mediating genome and nongenome reaction of ER. The deregulation of ER and MAPK signaling has been found in many tumors (such as breast cancer and EC). In this study, we use microarry to explore the differentially expressed genes between ER positive and ER negative EC. The expression of t-ERK1/2 and p-ERK1/2 in tissues of normal endometrium, hyperplasia endometrium and EC, as well as in the EC cell line RL95-2 and KLE were detected with immunohistochemistry and western blotting. Expression change of the t-ERK1/2 and p-ERK1/2 with estrogen, progesterone and tamoxifen treatment was also detected in RL95-2 and KLE with western blotting. The proliferation and apoptosis of RL95-2 and KLE after estrogen and tamoxifen treatment, as well as its relationship with MAPKs signaling were also analysed.The study was divided into three parts, as following:①Gene expression profiling analysis between ER positive EC and ER negative EC.②Investigation of the change for ERK1/2 singalling in EC.③The proliferation and apoptosis of EC cell lines and its relationship with MAPK signaling after estrogen and tamoxifen treatment.Part I Gene expression profiling analysis between ER positive and ER negative endotrial cancerObjective To identify the differentially expressed genes between ER positive EC and ER negative EC.Methods cDNA microarray was carried out in 32 endometrioid endometrial cancers. Differentially expressed genes were identified among EC tissues of ER positive and ER negative.Results Class comparison analysis between ER positive and ER negative endometrial cancer revealed 61 differentially expressed genes (P<0.001). Among them, five of the 61 genes belong to Mitogen-activated protein kinase singal pathway.Conclusion The cDNA microarray technique is a feasible way to generate gene expression profiles of endometrial cancer and identify the differentially expressed genes.Part II Investigation of the change for ERK1/2 singalling in endometrial cancerObjective To investigate the expression of t-ERK1/2 and p-ERK1/2 in endometrial cancer tissues and cell line, as well as expression change after estrogen, progesterone and tamoxifen treatment.Methods The expression of t-ERK1/2 and p-ERK1/2 in 20 normal endometrium, 13 hyperplasis endometrium and 30 endometrial cancer, as well as the endometrial cancer cell line RL95-2 and KLE were detected with IHC and western blot. The expression of t-ERK1/2 and p-ERK1/2 and its relationship to the clinical and pathologic factors of EC was also analysed. Expression change of the t-ERK1/2 and p-ERK1/2 after treating with estrogen, progesterone and tamoxifen was also detected in RL95-2 and KLE with western blotting.Results There was no difference for the expression of t-ERK1/2 and p-ERK1/2 among normal endometrium, hyperplasis endometrium and EC. The expression of t-ERK1/2 and p-ERK1/2 has no relation to FIGO stage, grade and myometrial invasion, lymph node metastasis(p>0.05).The expression of p-ERK1/2 was higher in ER positive EC(p<0.05).The expression of p-ERK1/2 was also higher in RL95-2 compared with KLE. The expression of p-ERK1/2 in RL95-2 and KLE were increased after estrogen treatment, and decreased after tamoxifen treatment.Conclusion The activation of ERK1/2 signaling was correlated with estrogen receptor status in endometrial cancer. The effects of estrogen and tamoxifen were mediated through ERK1/2 pathway.Part III The proliferation and apoptosis of endometrial cancer cell lines and its relationship with MAPKs signaling after treating with estrogen, progesterone and tamoxifenObjective To explore the proliferation and apoptosis of EC cell lines and its relationship with MAPKs signaling after treating with strogen and tamoxifen.Methods Endometrial cancer cell line RL95-2 and KLE were treated with estrogen and tamoxifen of various concentration. The proliferation and apoptosis of the cell lines were detected after 24h, 48h and 72h treatment. Results: Both of the 10nM~1μM estrogen can stimulate the proliferation of RL95-2和KLE. Tamoxifen (≥5μM) has the toxicity effect on RL95-2 and KLE. The ERK1/2 inhibitor U0126 could significantly suppress the proliferation effect of estrogen in RL95-2 and KLE. Tamoxifen could facilitate the apoptosis of KLE, but has no effect on RL95-2. The JNK signaling pathway took part in the apoptosis regulation of RL95-2 and KLE.Conclusion:The proliferation effect of estrogen on endometrial cancer cells has no relationship with the expression of estrogen receptor, which was mediated through ERK1/2 signaling pathway. The apoptosis effect of tamoxifen correlated with the expression of estrogen receptor. The apoptosis effect was mediated through JNK pathway, in endometrial cancer cell line RL95-2 and KLE.