Objective: To investigate the reversal effect of nitidine chloride(NC) on human oral squamous cell carcinoma KB/adriamycin(ADM). Method: The KB/ADM cells were cultured conventionally to 1×106

randomly divided into five groups:KB/ADM cells group

positive control verapamil group(VRP

5 μmol·L-1)

low dose group of NC(0.375 mg·L-1)

middle dose group of NC(0.75 mg·L-1)

high dose group of NC(1.5 mg·L-1)

3 parallel samples each.These groups were respectively added to the same volume of culture medium

5 μmol·L-1 VRP

0.375

0.75

1.5 mg·L-1 NC for 48 h.The cell sensitivity to chemotherapeutic drugs was demonstrated by MTT. The effect of NC on p-glyco protein(P-gp) expression was analyzed by flow cytometry. Multidrug resistance gene-1(MDR-1) expression was detected by RT-PCR. Result: Compared with KB/ADM cells group

the IC50 value of positive control VRP group

low dose

middle dose and high dose group of NC to ADM

vincristine(VCR)

estoposide(VP-16)

hydroxycamptothecin(HCPT) were decreased significantly(P<0.01

P<0.05). The P-gp expressions in VRP group

low

middle and high dose group with NC were respectively (10.60±1.11)%

(68.57±2.56)%

(28.29±1.98)%

(8.03±1.46)%

compared with KB/ADM cells group(97.33±1.61)%

all of them were decreased significantly(P<0.01).The MDR1-mRNA expressions of positive VRP group

low dose

middle dose and high dose group with NC decreased by 39%

22%

46%

69%(P<0.01)compared with KB/ADM cells group. Conclusion: NC can reverse the multidrug resistance of KB/ADM.