Abstract: Background and purpose: The expression and role of zinc finger protein ZIC2 are tissue-specific in various types of cancers, and its abnormal expression is closely related to the prognosis of tumors. However, there is no corresponding research on the expression and role of ZIC2 in prostate cancer. This study aimed to detect the expression of ZIC2 protein in prostate cancer tissues and cells, and to determine the relationship between ZIC2 abnormalities and pathological parameters and the effects on proliferation and apoptosis of prostate cancer cells. Methods: The expression of ZIC2 was detected using immunohistochemical SP method in the specimens from 31 cases of prostate cancer diagnosed by biopsy and 35 cases of benign prostatic hyperplasia (BPH) by transurethral resection of the prostate (TURP). The relationship between abnormal expression and clinicopathological parameters was analyzed. ZIC2 gene was treated with small interfering RNA (siRNA) in prostate cancer cells DU145, and protein expression of ZIC2 was verified by Western blot. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT). Cell cycle and apoptosis of prostate cancer cells were detected by flow cytometry. Results: The positive rates of ZIC2 expression in prostate cancer tissues and BPH were 90.32% (28/31) and 20.00% (7/35), respectively (χ²=32.639, P=0.000). The positive rate of ZIC2 expression was closely related to the Gleason score in prostate cancer specimens (χ²=9.753, P=0.003), while there was no exact correlation between prostate-specific antigen (PSA) and invasion depth of tumor (P>0.05). Due to ZIC2 being interfered by siRNA, the protein of ZIC2 was significantly decreased in prostate cancer cells. The results of MTT showed that the tumor growth was significantly slower following RNA interference, and the results of flow cytometry showed that ZIC2 could effectively inhibit the proliferation and promote apoptosis of prostate cancer cells. Conclusion: ZIC2 has increased expression in prostate cancer, and acts as an oncogene. ZIC2 expression is closely related to the Gleason score. Suppression of ZIC2 expression effectively inhibits proliferation of prostate cells and induces apoptosis.

Key words: Zinc finger protein ZIC2, Cell proliferation and apoptosis, Prostate cancer