Objective: To investigate the mechanisms and reversal effects of Jianpi Jiedu formula on human colon carcinoma multidrug resistance（MDR） in HCT8/V cells.Method: Human colon carcinoma MDR cells were cultured conventionally.The concentration of Jianpi Jiedu formula（5%） combined with chemotherapy drugs and the reversal effect of multidrug resistance（MDR） in HCT8/V cells was evaluated by the MTT assay.The variation of intracellular concentration of vincristine（VCR） in HCT8/V cells was evaluated by the HPLC

and the effects of Jianpi Jiedu formula on 5-Fu induced apoptosis and cell cycle were evaluated by flow cytometry（FCM）.Result: Jianpi Jiedu formula could increase the sensitivity of HCT8/V cells to VCR

DDP

5-Fu

THP.The IC50 value of VCR decreased from（191.08±18.18） mg·L-1 to（90.13±6.33） mg·L-1

DDP was from（290.79±28.38） mg·L-1 to（22.16±1.82） mg·L-1

5-Fu was from（23.12±1.99） mg·L-1 to（9.88±0.86） mg·L-1

and THP was from（26.40±2.92） mg·L-1 to（19.41±1.48） mg·L-1.HPLC results showed that Jianpi Jiedu formula increased the concentration of drugs in HCT8/V cells in a dose-dependent manner after treatment for 48 h.Flow cytometry assay result verified that the inhibited effects of Jianpi Jiedu formula combined with 5-Fu on the proliferation of HCT8/V cells was closely related to the arrest in G1 phase and increasing of apoptosis.Conclusion: Jianpi Jiedu formula can reverse MDR in HCT8/V cell

which possibly through inhibiting cell proliferation

inducing cell-apoptosis

ultimately affect the concentration of drugs inside the cells.