Objective: Prostate cancer is one of the most frequently diagnosed cancer in men and ranks as the second most common cause of cancer-related deaths in developed countries. HN1 is a highly expressed gene in prostate cancer and controls the levels of several cell cycle regulatory proteins including Cyclin B1. Cyclin B1 is a cell cycle control protein but is also involved in Docetaxel and 2-Methoxyestradiol induced apoptosis. Since Cyclin B1 level may affect chemotherapy success and HN1-Cyclin B1 negative correlation has already been shown, so in this study, we investigated the possible role of HN1 in chemotherapeutic resistance in prostate cancer cells.
Methods: Androgen-dependent and independent prostate cancer cells were used in the study. A full-length human HN1 cDNA fragment was cloned to a mammalian expression vector and this construct was used for overexpression experiments. A siRNA that specifically targets HN1 was used for HN1 depletion experiments. Evaluation of apoptosis was performed by the level of PARP cleavage and an apoptosis kit that measure Caspase 3 activity.
Results: The HN1 protein level is decreased in the Docetaxel or 2-Methoxyestradiol treated LNCaP and PC-3 PCa cells whereas the Cyclin B1 level is increased. HN1 overexpression inhibited Docetaxel and 2-Methoxyestradiol induced apoptosis. In concordance, its depletion further stimulated apoptosis in drug-treated cells. However, silencing of Cyclin B1 along with HN1 abolished the increased apoptotic response induced by silencing of HN1 in Docetaxel or 2-Methoxyestradiol treated cells.
Conclusion: HN1 is an anti-apoptotic molecule and inhibits Docetaxel and 2-Methoxyestradiol induced apoptosis by targeting Cyclin B1.
Keywords: 2-Methoxyestradiol; Apoptosis; Cyclin B1; Docetaxel; HN1.
© 2022 by the Association of Clinical Scientists, Inc.