Effects Of Two Variants Of The HCAP1 Gene On Proliferation And Apoptosis In Lymphoma/Leukemia Cell Lines

Objective: HCAPI (Hepatocelluar carcinoma-associated protein 1) gene wasmapped at chromosome 17p13,3, a region with a high frequency of loss of heterzygosity (LOH). Two haplotypes, HCAP1-N (with common alleles at 5 SNP site) and HCAP1-M (with minor alleles at 5 SNP site) have been isolated. This study was designed to investigate the effects of both variants of HCAPI gene on cell proliferation and apoptosis in Raji and Jurkat lymphoma/leukemia cell lines, and the effects on the expression of p53 and p21 proteins, which are known to been related with the regulation of cell cycle checkpoint and apoptosis.Methods: The two variants of HCAPI gene were separately transfected into Rajiand Jurkat cells by medium with liposome, the overexpression of exogenous HCAPI gene was detected using Western blot assay. Cell viability was assessed using trypan blue dye exclusion test. The ratio of S-phase was measured using BrdU (5-bromo- 2'-deoxy-uridine) labeling and detection assay. The cell apoptosis was measured using TUNEL Assay. The expression of p53 and p21 proteins was examined using Western blot assay.Results: Compared with the control cells transfected with empty vectors or withoutany transfection, (1)Raji and Jurkat cell transfected with HCAP1N or HCAP1M displayed suppressed cell viability and reduced percentage of BrdU incorporating cells, which is lower in the cells tranfected with HCAP1N than that in the cells tranfected with HCAPlM;(2)Raji cells tranfected with HCAP1N or HCAP1M displayed increased percentage of apoptotic cells, which is higher in the cells tranfected with HCAP1N than that in the cells tranfected with HCAP1M; (3)Raji cells tranfected with HCAP1N or HCAP1M exhibited increased expression levels of the p53 and the p21 proteins. The p53 protein level is higher in the cells transfected with HCAP1N than that in cells tranfectedwith HCAPIM. However, the p21 protein level is similar between the two subtypes of cells tranfected with different variants of HCAPl gene.Summary: Overexpression of both variants of HCAPl (HCAPIN and HCAPIM)could obviously inhibit proliferation in Raji and Jurkat cells and induce apoptosis in Raji cells. However, the effect of HCAPIN was stronger than that of HCAPIM. Overexpression of both variants in Raji cell could significantly upregulate the expression of the p53 and the p21 proteins. However, the up-regulation of the HCAPIN on the p53 protein expression is stronger than that of HCAPIM, the up-regulation of both variants of HCAPl on the p21 protein expression is similar.