Ectopic HCG In Endometrial Carcinoma And Its Effect On COX-2 Expression

Background:Since 1960s, ectopic human chorionic gonadotrophin (ehCG) has been observed in many malignant tumors, which is related to the initiation, progression, malignisation and metastasis of tumors. But ehCG in endometrial carcinoma is rarely reported. Physiological hCG plays an important role in normal development of the fetus, which promotes both cell proliferation and angiogenesis for implantation. Simultaneously, increased cyclooxygenase-2 (COX-2) expression in endometrial carcinoma has the same effect on cell proliferation and angiogenesis. It was reported that hCG promotes both cell proliferation and angiogenesis for implantation by upregnlating the expression of COX-2 in endometrium. In order to study the significance of ectopic hCG., we investigate the effect of hCG on COX-2 expression in endometrial carcinoma.Objective:To elucidate the ectopic human chorionic gonadotrophin (ehCG) expression in malignant tumor cells and the effect of exogenous hCG on endometrial carcinogenesis, as well as the significance of hCG in diagnosing and treating endometrial carcinoma, we studied the autocrine of ehCG in endometrial carcinoma cell lines, and the presence of ahCG,βhCG and COX-2 in endometrial carcinoma tissues. Furthermore, we also observed the effect of exogenous hCG on nude mice transplanted tumors and investigated the effect of hCG on COX-2 expression in endometrial carcinoma. Methods:1. The well-differentiated and moderately differentiated human endometrial carcinoma cell line EAC and JEC, human MCF-7 breast cancer cell line were investigated. 1.5×10⁵ cells of each cell line were cultured with serum free RPMI1640 medium in a humidified 5% CO₂ atmosphere at 37℃. After incubation for 24h, 48h and 72h, the supernatant was collected, respectively, for hCG detection by radioimmunoassay (RIA).2. A series of atypical hyperplasia of endometrium group 30 cases and endometrial carcinoma group 20 cases have been examined immunohistochemically for protein level of ahCG,βhCG and COX-2.3. Human endometrial carcinoma xenograft tumor in nude mice was established. After hCG was injected to the nude mice intraperitoneally, the effect of hCG on xenografts growth was evaluated by tumorigenecity and xenografts weights, as well as the expression Ki-67 was determined by immunohistochemistry. Moreover, we applied H&E staining to observe the morphologic changes and measure the area of necrosis. In addition, we evaluated the effect of hCG on fibrosis with Masson staining.4. The effect of hCG on the cell viability and the inhibition of selective COX-2 inhibitor NS398 on the cell line JEC was studied by MTT assay. The hCG inducing COX-2 expression was detected by Western blotting.Results:1. Ectopic hCG increased both in EAC and JEC cell lines, especially in JEC cell line, when the culture time prolonged. After the cells were cultured for 24h, 48h and 72h, the quantities of ectopic hCG in JEC were 1.83 IU/L, 10.20 IU/L and 28.94 IU/L, and in EAC were 3.35 IU/L, 4.06 IU/L and 10.34 IU/L, respectively. The quantities of ectopic hCG in both call lines were in accordance with linear regression (F=4.329, P=0.076). The quantity of ectopic hCG secretion was higher in the moderately differentiated endometrical carcinoma cell line than in the well differentiated.2. The rate of the ahCG expression in endometrial carcinoma group and the atypical hyperplasia of endometrium group were 50% and 0%. There was no expression ofβhCG in these two groups. The positive rates of the COX-2 expression in the two groups were 80% and 100%, respectively.3. In contrast to the control group, the xenografts cells in the hCG treatment group have the tendency to form glandular structure stained by H&E. There was no statistical significance in other index.4. HCG promoted the cell viability of JEC cell line through upregulating the COX-2 protein and increased the inhibitory effect of selective COX-2 inhibitor NS398 on JEC cell line.Conclusions:1. The cell lines of endometrial carcinoma had potential autocdne function of ectopicβhCG, especially in the poorer differentiated one. It suggested that the level ofhCG secretion is closely associated with malignancy.2. The expression of ahCG was detected not in endometrial atypical hyperplasia tissues but in endometrial carcinoma ones, which suggest that ahCG may act as one of the differential diagnosis index between endometrial carcinoma and atypical hyperplasia of endometrium.3. HCG promoted the differentiation of the endometrial carcinoma cells in vivo.4. The ectopic hCG in JEC endometrial carcinoma cell line increases cell proliferation, which may be mediated by upregulating the expression of COX-2 protein. The presence of ectopic hCG is speculated associated with dedifferentiation in malignant.