Multidrug resistance is one of the main impediments to the successful treatment of colon cancer. Glucosylceramide synthase (GCS) which is related to multidrug resistance (MDR) can reduce the level of ceramide and can help cells escape from the ceramide-induced cell apoptosis. However, the underlying mechanism is still unclear.

The cell proliferation and cell toxicity were measured with Cell Counting Kit-8 (CCK-8). The mRNA levels of GCS and MDR1 were detected by semiquantitative reverse transcription-PCR amplification, the protein levels of GCS, caspase-3 and P-gp proteins were indicated by Western blotting. The apoptosis rates of cells were measured with flow cytometry.

The relative mRNA levels of GCS in HCT-8, HCT-8/VCR, HCT-8/VCR- sh-mock and HCT-8/VCR-sh-GCS were 71.4 +/- 1.1%, 95.1 +/- 1.2%, 98.2 +/- 1.5%, and 66.6 +/- 2.1% respectively. The mRNA levels of MDR1 were respectively 61.3 +/- 1.1%, 90.5 +/- 1.4%, 97.6 +/- 2.2% and 56.1 +/- 1.2%. The IC50 of Cisplatin complexes were respectively 69.070 +/- 0.253mug/ml, 312.050 +/- 1.46mug/ml, 328.741 +/- 5.648mug/ml, 150.792 +/- 0.967mug/ml in HCT-8, HCT-8/VCR, HCT-8/VCR-sh-mock and HCT-8/VCR-sh-GCS. The protein levels of caspase-3 were 34.2 +/- o.6%, 93.0 +/- 0.7%, 109.09 +/- 0.7%, 42.7 +/- 1.3% respectively. The apoptosis rates of cells were 8.77 +/- 0.14%, 12.75 +/- 0.54%, 15.39 +/- 0.41% and 8.49 +/- 0.23% respectively.

In conclusion, our research indicated that suppression of GCS restores the sensitivity of multidrug resistance colon cancer cells to drug treatment.

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