[Expression of glucosylceramide synthase mRNA in vincristine-resistant KBV200 cell line in association with multidrug resistance].

OBJECTIVE: To investigate the relationship between the expression of glucosylceramide synthase (GCS) mRNA in vincristine-resistant KBV(200) human cancer cell line and multidrug resistance (MDR) of the cancer cells.

METHODS: Reverse transcriptional polymerase chain reaction (RT-PCR) was employed to analyze the differential expression of GCS mRNA between KBV(200) and KB cell lines and the changes in the mRNA expressions of GCS and mdr1 gene in KBV(200) cells after reversion of MDR. The effects of de-phenyl-z-palmaitoylamino-3-morpholine-1-propanol (DL-PPMP) and verapamil in reversing MDR of the cells were evaluated by MTT assay.

RESULTS: KBV(200) cells exhibited significantly increased expressions of GCS and mdr1 gene, whereas mdr1 gene failed to be detected in the parental KB cells. DL-PPMP within the concentrations ranging from 5 to 25 micromol/L could inhibit the expression of GCS gene, with the maximum inhibition achieved at 25 micromol/L. Verapamil at the concentration of 10 micromol/L was already sufficient to induce inhibition of GCS expression in KVB(200) cells, which was more manifest with the concentration of 15 micromol/L. DL-PPMP and verapamil were found to inhibit mdr1 gene expression in KBV(200) cells at the mRNA level, and complete inhibition occurred after a 48-hour DL-PPMP treatment at 25 micromol/L.

CONCLUSION: The inhibition of GCS and mdr1 gene expressions is positively correlated with the concentrations of DL-PPMP and verapamil, which can reverse MDR by inhibiting synthesis of GCS and mdr1 gene, indicating the positive correlation between the expression of GCS gene and MDR in KBV(200) cells. GCS gene might play an important role in MDR during tumor progression.