Rac Gene Expression In Hematologic Malignancies And Its Effects On The Proliferation And Apoptosis In HL-60 Cells

AIM: The Rac guanosine triphosphatases (GTPases) are members of the Rho superfamily which regulate many different cellular processes such as actin assembly, adhesion, motility, proliferation and Apoptosis. It is becoming more evident that Rac GTPases may play the specific roles in tumor initiation, progression and metastasis.But there are few studies about Rac in Hematologic Malignancies. There are no reports about Racl, Rac2 expression in different hematologic malignancies and the direct effects of Racl on the cell cycle progression and apoptosis in HL-60 cells. In order to find the relation between Racl , Rac2 and hematopoietic cells proliferation and multidrug resistance , the study was to investigate the mRNA level of Racl and Rac2 in human nomal peripheral blood mononuclear cells(PBMC), leukemia cells , lymphoma cells, myeloma cells and multidrug resistance cell line HL-60/VCR cells. In addition, we used Racl antisense oligodeoxynucleotide (ASODN) to observe the role of Racl in the regulation of HL-60 cells morphous ,cycle progression, proliferation and apoptosis.METHODS: The mRNA expression of Racl and Rac2 in human PBMCs, leukemia cell lines (HL-60, K562, U937, NB4 cells), lymphoma cell line(Raji cells), myeloma cell line( RPMI8226 cells) and multidrug resistance cell line (HL-60/VCR cells) were examined by semi-quantitative RT-PCR. After transfection of HL-60 cells with different concentrations of Racl ASODN by means of FuGENE6, the effect of transfection was examined by semi-quantitative RT-PCR, the survival, cell cycle, apoptosis of HL-60 cells were observed by MTT assay, FCM test , Wright-Giemsa, Acridine Orange/ethidium bromide(AO/EB) and Annexin V - FITC/PI staining test, respectively.RESULTS: 1.The semi-quantitative RT-PCR showed that there were expressions of Racl and Rac2 in HL-60, U937, K562, NB4, Raji, RPMI8226 cells, the mean mRNA expressions of Racl(Racl/GAPDH) and Rac2(Rac2/GAPDH), compared with the normal PBMCs, were upregulated(P <0.01) , but there was no difference among those cell lines.2. There was no difiference in the mean mRNA expression levels of Racl and Rac2 between HL-60 cells and multidrug resistance cell line HL-60/VCR cells.3. Compared with HL-60 cells exposured to sense oligodeoxynucleotide (SODN), the viability of HL-60 cells exposured to ASODN decreased( P<0.01), furthermore , the viability decreased accordingly with the concentration of ASODN increasing, the proportion of G1 cells increased [ (52.1±6.8) %vs(32.8±3.9) % ,P<0.01], the percentage of AnnexinV+/PI- cells increased [ (9.4±2.1) % vs (2.3±1.7)%, P<0.01] , and formation of apoptotic bodies were observed in HL-60 cells .CONCLUSIONS: 1. The mean mRNA expressions of Racl and Rac2...