Clinicopathological significance of increased ZIC1 expression in human endometrial cancer

Zinc finger of the cerebellum (ZIC1), one of ZIC family genes, has been shown to play important roles in many cancers such as gastric cancer and breast cancer. However, there is little known about the expression and significance of ZIC1 in endometrial cancer. The aim of this study was to determine the expression pattern and clinicopathological significance of ZIC1 in endometrial cancer. The mRNA and protein expression of ZIC1 in endometrial cancer tissues was detected using the reverse-transcription polymerase chain reaction and Western blotting, respectively. Immunostaining of ZIC1 in 99 endometrial cancer samples was examined and its associations with clinicopathological parameters were analyzed. Hec-1-B cells were transfected with ZIC1-shRNA or sc-shRNA, and cell proliferation was assayed. Hec-1-B cells stably transfected with ZIC1-shRNA or sc-shRNA were subcutaneously inoculated into nude mice, and the tumor weight was measured. A significantly increased expression of ZIC1 mRNA and protein was observed in endometrial cancer tissues compared to that in normal endometrial tissues (P<0.05). Immunohistochemical analysis showed that strong cytoplasmic immunostaining of ZIC1 was observed in almost all endometrial cancer samples (90/99) while light and moderate immunostaining of ZIC1 was only detected in 17 of 30 (56.7%) normal tissues. Moreover, up-regulation of ZIC1 was significantly correlated with age, disease stage, TNM stage and FIGO stage (P<0.05). The down-regulated expression of ZIC1 contributed to the inhibition of cell proliferation, and inhibited the growth of tumor. It was concluded that ZIC1 is over-expressed in endometrial cancer tissue but not in normal tissue, and positively correlated to the malignant biological behavior of endometrial carcinogenesis.