BACKGROUND AND OBJECTIVELetrozole is an aromatase inhibitor that is used in the treatment of estrogen-sensitive tumors such as endometrial carcinoma, however, its therapeutic effect is still to be further improved. It is reported that curcumin has antitumor capability and can enhance the sensitivity of tumor cells to anticancer agents. This study was to investigate the inhibitory effect of letrozole combination with curcumin on the implanted endometrial tumor growth.

METHODSNude mice were implanted with endometrial carcinoma RL-952 cells. All tumor-bearing mice were randomly divided into 5 groups: control(without treatment), Let(1) (letrozole, 1 microg/d), Let(10) (letrozole, 10 microg/d), Cur [ curcumin, 300 mg/kg.d)], and Let + Cur group [10microg/d letrozole + 50mg/ (kg.d) curcumin]. The tumor growth was monitored. Tumor cells apoptosis was detected in both control and treated groups. The expressions of bcl-2 mRNA and bcl-2 protein were detected using RT-PCR and Western blot, respectively.

RESULTSFifty mice were successfully implanted with the endometrial tumor. Treatment with letrozole markedly inhibited tumor growth; the inhibitory effect was further enhanced by the combination of letrozole and curcumin. The inhibitory rates in Let (1), Let (10), the Cur, and the Let + Cur groups were 15.95%, 22.49%, 21.57%, and 35.89%, respectively. Treatment with curcumin inhibited the expression of bcl-2 in tumor cells at the mRNA and protein levels. The apoptosis rates in the control group and the four experimental groups mentioned above were 16.97%, 32.90%, 35.80%, 34.16%, and 47.24%, respectively. Tumor cells apoptosis were observed in mice treated with either letrozole or curcumin; however, combination of letrozole and curcumin further enhanced the inhibitory rate in tumor growth.

CONCLUSIONSTreatment with letrozole or curcumin could inhibit the xenografted endometrial tumor growth by inducing apoptosis in tumor cells. Combination of letrozole and curcumin further enhanced the inhibitory effect of tumor growth.