RESUMO
Objective: To investigate the effect of overexpression of Twist1 on multidrug resistance( MDR) in colorectal cancer SW620 cells and its possible mechanism. Methods: The colorectal cancer SW620 cells were transfected with Twist1 overexpressing lentivirus and negative control virus, which were called experimental group ( SW620-Twist1) and control group ( SW620-NC) respectively. The protein and mRNA expression of Twist1、ABCB1 and ABCG2 in two groups were detected by Western blot and RT-qPCR, respectively. The growth inhibitory rate of 5-Fluorouracil(5-FU) and Oxaliplatin( OXA) at 24 ,48 and 72 h in two groups were determined by CCK8 assay. Cancer stem cell markers CD133,CD44 expression levels were detected by Flow cytometry. Results: The experimental group was compared with the control group, the expressions of Twsit1 gene mRNA and protein increased significantly( P<0. 01) ,Twist1 gene overexpressing SW620 cell line was successfully constructed. The inhibition rates of cell proliferation of the three chemotherapeutic drugs at 48 h and 72 h were significantly decreased ( 48 h, P<0. 05 ; 72 h, P<0. 01) . The mRNA and protein expression levels of ABCB1,ABCG2 were significantly increased( P<0. 01). The expression of CSCs markers CD133 and CD44 increased significantly (P<0. 01). Conclusion: Overexpression of Twist1 can promote the expression of ABCB1 and ABCG2 genes in SW620 cells and make the tumor cells acquire MDR. This phenomenon may be related to the promotion of stemness.
RESUMO
<p><b>AIM</b>To investigate apoptosis induced by 3,3'-diethyl-9-methylthia-carbocyanine iodide (DMTCCI), an inhibitor of DNA primase found in our previous study, and the mechanism of DMTCCI in human myelogenous leukemia HL-60 cells.</p><p><b>METHODS</b>HL-60 cells were cultured in RPMI-1640 medium and treated with different concentrations of DMTCCI. MTT assay was used to detect growth inhibition. Flow cytometry and DNA ladders were used to detect apoptosis. Western blotting was used to observe the expression of survivin, Bcl-xL, Bad, Bax, Bcl-2, caspase-9, caspase-3, caspase-6, PARP, DFF45 and lamin B protein. Caspase-3 activity was measured by ApoAlert Caspase-3 Assay Kit.</p><p><b>RESULTS</b>DMTCCI inhibited proliferation of human leukemia HL-60 cells with IC50 value of 0.24 micromol x L(-1). The results of flow cytometry and DNA ladders showed that DMTCCI could induce apoptosis of HL-60 cells. The expression levels of protein survivin and Bcl-xL were down-regulated, Bad and Bax were up-regulated, while Bcl-2 protein had no change in response to DMTCCI treatment in HL-60 cells. Treatment of HL-60 cells with DMTCCI induced the proteolytic cleavage of caspase-9, caspase-3, caspase-6, PARP, DFF45 and lamin B protein. Caspase-3 activity apparently increased at 3 h and reached a peak at 12 h after exposure to 1 micromol x L(-1) of DMTCCI in HL-60 cells.</p><p><b>CONCLUSION</b>DMTCCI inhibited proliferation and induced apoptosis of human leukemia HL-60 cells. Bcl-2 family proteins, survivin and caspases family proteins might play a role in the apoptosis process induced by DMTCCI.</p>