Abstract: Objective: To investigate the effects of hematopoietic progenitor kinase 1 (HPK1) overexpression by construction of lentiviral vector on the proliferation and apoptosis of breast cancer MCF-7 and MDA-MB-231 cells, and to elucidate its possible mechanism. Methods: The cells were infected with the lentivirus overxpressing HPK1,and the MCF-7-HPK1 and MDA-MB-231-HPK1 cell lines were stably expressed HPK1;each cell line was divided into three experimental groups:blank group (untreated), control group(empty vector) and HPK1-overexpression group. The expression levels of HPK1 mRNA and protein in breast cancer cells in each group were detected by RT-PCR and Western blotting methods, respectively. The cell proliferation rate was detected by MTT assay. The cell cycle and apoptotic rate were detected by flow cytometry. Transwell assay was used to analyze the cell migration ability. Western blotting method was used to measure the expression levels of caspase 3, PTEN, MMP-9,MMP-2, Ki-67and HPK1 proteins. Results: Compared with blank groups and control groups, the expression levels of HPK1 mRNA and protein in the both cell lines in HPK1 overexpression groups were significantly up-regulated(P<0.05), the proliferation rates were significantly decreased(P<0.05) and the apoptotic rates were significantly increased(P<0.05), the number of cells crossing matrigel was significantly reduced(P<0.05), the cell cycle of MCF-7 was blocked in G1 phase(P<0.05), the expression levels of caspase 3 and PTEN proteins in HPK1 overexpression group were significantly increased(P<0.05), and the expression levels of MMP-2 and MMP-9 proteins were significantly decreased (P<0.05). Conclusion: HPK1 overexpression can inhibit the proliferation and migration of MCF-7 and MDA-MB-231 cells and induce apoptosis, which may be related to the up-regulation of caspase 3 and PTEN and down-regulation of MMP-9, MMP-2 and Ki-67.

Key words: hematopoietic progenitor kinase 1, breast cell lines, cell proliferation, apoptosis