This result indicated these two proteins have some relations. This result is consistent with the recently published work by liu et al. [21]. We also found that the protein level of caspase-3 was higher in insensitive cells than in sensitive cells. Our research

also found that the expression of GCS protein was much higher in HCT-8/VCR than that in HCT-8. And so was the protein level of P-gp. When the HCT-8/VCR was transfected with UGCG shRNA Plasmid, the protein levels of GCS and P-gp were decreased. The results indicated that there may be a relation between GCS and P-gp proteins. Cytotoxity results demonstrated that HCT-8/VCR needs a much higher drug concentration to get 50% inhibition of cell growth. The needed drug concentration decreased when HCT-8/VCR was transfected with UGCG shRNA Plasmid. This result OICR-9429 concentration indicated that drug resistance SIS3 cost in HCT-8/VCR was reversed. The higher level of the apoptotic gene in the insensitive cells may contribute to the result. Although the drugs can induce apoptosis, the cells with high level GCS may be better able to adapt to the new circumstances, while the sensitive cells may not. The apoptosis rate was higher in insensitive cells than sensitive cells.

The result is different with the other DZNeP solubility dmso researchers. The reason may be the coactions of many apoptotic and anti-apoptotic proteins. In conclusion, our research demonstrated that GCS play an important role in multidrug resistance mechanisms of colon cancer cells with high expression of GCS gene. The up-regulation of GCS could affect the expression of MDR1 in colon cancer cells. They may cooperate with each other in the formation of multidrug resistance. Acknowledgements We appreciate the assistances that have been provided by Department of Human Anatomy, Zhengzhou University. We would like to express our thanks to Dr Glutamate dehydrogenase Fred Bogott for critically reading this manuscript and

giving good suggestions. References 1. Patwardhan G, Gupta V, Huang J, Gu X, Liu YY: Direct assessment of P-glycoprotein efflux to determine tumor response to chemotherapy. Biochem Pharmacol 2010, 80:72–79.PubMedCrossRef 2. Baguley BC: Multiple drug resistance mechanisms in cancer. Mol Biotechnol 2010, 46:308–316.PubMedCrossRef 3. Gouaze V, Yu JY, Bleicher RJ, Han TY, Liu YY, Wang H, et al.: Overexpression of glucosylceramide synthase and P-glycoprotein in cancer cells selected for resistance to natural product chemotherapy. Mol Cancer Ther 2004, 3:633–639.PubMed 4. Chen T: Overcoming drug resistance by regulating nuclear receptors. Adv Drug Deliv Rev 2010, 62:1257–1264.PubMedCrossRef 5. Zhang X, Li J, Qiu Z, Gao P, Wu X, Zhou G: Co-suppression of MDR1 (multidrug resistance 1) and GCS (glucosylceramide synthase) restores sensitivity to multidrug resistance breast cancer cells by RNA interference (RNAi). Cancer Biol Ther 2009, 8:1117–1121.PubMedCrossRef 6. Liu Y, Xie KM, Yang GQ, Bai XM, Shi YP, Mu HJ, et al.

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