OBJECTIVETo investigate the inhibitory effects of CaMKIIN on acute myeloid leukemia cell line HL-60 to explore a novel therapeutic target of leukemia.

METHODSHuman CaMK II N gene expression vector pcDNA3.1/hCaMKIIN or empty vector pcDNA3.1/myc-His (-) B was transfected into HL-60 cells by Lipofectamine 2000. Human CaMK II N proteins of transfected cells were detected by Western blot. Cell proliferation affected by human CaMKIIN was determined by MTT. Colony-forming assay was performed by soft agar growth system. The cells transfected with CaMKIIN were stained with Hoechst 33342 to detect the apoptotic proportion under fluorescence microscopy. Cell cycle was analyzed by flow cytometry.

RESULTSHuman CaMKIIN was stably transfected into HL-60 cells, and overexpression of human CaMKIIN inhibited the proliferation of HL-60/CaMKIIN cells compared to HL-60/mock cells and HL-60 cells [(0.44 ± 0.03) vs (0.94 ± 0.05) vs (0.94 ± 0.04), P<0.01]. The colony formation of HL-60/CaMKIIN was also markedly smaller[(21.00 ± 3.05)/500] than that of mock-transfected [(111.00±4.58)/500]] and control cells [(119.00±6.09)/500] (P<0.01). After 72 hrs-culture, the apoptotic proportion in cells transfected with CaMK II N was obviously higher than of cells transfected with mock DNA or control [(22.49 ± 2.15)% vs (7.17 ± 0.72)% vs (6.40 ± 0.55)%, P<0.01]. Up to (82.97 ± 2.90)% human CaMKIIN/HL-60 cells were arrested at G0/G1 phase, which was more than mock-transfected [(40.53 ± 2.38)%] and control cells [(41.63 ± 2.27)%] (P<0.05). Human CaMKIIN could down-regulate expression of Bcl-2 in transfected cells.

CONCLUSIONCaMK IIN up-regulation could inhibit proliferation and induce apoptosis of human acute myeloid leukemia cell HL-60.