Abstract: Objective The Objective of this study was to explore the role and mechanism of long non-coding RNA(lncRNA)HCP5 in triple-negative breast cancer. Methods The mRNA content of HCP5 in breast cancer cell lines and normal breast cell lines was analyzed by qPCR,and the RNA Scope method was used to analyze the expression of HCP5 in breast tissues and breast cancer tissues.The effect of knocking-down HCP5 on the proliferation of triple negative breast cancer cells was analyzed by CCK-8 and cell survival/death experiments.The effect of knockdown HCP5 on the proliferative ability of breast cancer cells was analyzed in nude mice.Antibody microarray technique was used to analyze the effect of knockdown HCP5 on the expression of BIRC3 and caspase-3 proteins in the apoptotic pathway. Results Compared with normal breast cells and other types of breast cancer cells,HCP5 was up-regulated in triple negative breast cancer cell lines(P＜0.05).Compared with normal breast tissues and other subtypes of breast cancers,HCP5 in triple negative breast cancer tissues were up-regulated(P＜0.05).Compared with the control group,triple-negative breast cancer cells in the HCP5 knockdown group were decreased proliferation,increased apoptosis of triple negative breast cancer cells,and inhibited the growth of orthotopic tumor in nude mice(P＜0.01).Knockdown of HCP5 caused a decrease expression of apoptotic inhibitor BIRC3 and an increase expression of Caspase-3 in the apoptotic pathway,the difference was statistically significant(P＜0.05).There was no difference in the effect on the MAPK signaling pathway protein between wild and HCP5 knockdown groups. Conclusion lncRNA HCP5 promotes the malignant progression of triple negative breast cancer through regulating the apoptotic pathway.

Key words: lncRNA, HCP5, Triple negative breast cancer