The IC_(50) of YIQIJIEDU Tablets (Chinese Herbs)killing NPC cells with MTT assay were measured,and the NPC cells was treated under several
concentration as 10 IC_(50), IC_(50) and 0. 1 IC_(50) for 12h, 24h, 48h, 72h and 96h with the herbs. Telomerase and
telomerase RNA in these cells were assaied. The results showed that YIQIJIEDU Tablets at high concentration (10 IC_(50))inhibited
Telomerase activity and telomerase RNA expression in NPC cells, and it was tile same as cyclophosphamide; Under lower concentration, it also inhibited telomerase activity, but its
effect was less significant than at high concentration; Although the lowest concontration YIQIJEIDU Tablets used in the experiment could not inhibit telomerase activity and telomerase RNA expression in NPC cells, the telomerase activity level of target cells was lower than that of blank control. The findings suggest that the anticancer effect of the. Chinese herbs link with their inhibitory effects on telomerase and telomerase RNA .