OBJECTIVETo determine the enhancement effects of caffeine on chemotherapy of transplanted osteosarcoma in Fischer 344/N rats.

METHODSOsteosarcoma-bearing Fischer 344/N rats were treated with cisplatin 2.5 mg/kg (Group DDP), caffeine 90 mg/kg x 2 d (Group caffeine), and cisplatin 2.5 mg/kg plus caffeine 90 mg/kg x 2 d (Group DDP+caffeine), and the control group was treated with normal saline in the same volume. All drugs were given by intra-peritoneum injection with micro-pump, in the rate of 0.5 ml/h. The tumor volume was measured and evaluated. The tumors were stained in TUNEL, and PCNA was detected with immunohistochemistry. The tumor growth inhibition rate, PCNA index and apoptosis index were calculated, and the survival time were recorded.

RESULTSThe tumor inhibition rate was -0.5219 +/-0.1429 in control group, 0.0362 +/-0.0957 in Group DDP, -0.4193 +/-0.1345 in Group caffeine, and 0.3646 +/-0.1313 in Group DDP+caffeine (P <0.01). PCNA index was 0.4587 +/-0.1312 in control group, 0.1847+/-0.0535 in Group DDP, 0.4381 +/-0.0706 in Group caffeine, and 0.0314 +/-0.0231 in Group DDP+caffeine (P <0.01). Apoptosis index was 0.0008 +/-0.0005 in control group, 0.0077 +/-0.0060 in Group DDP, 0.0011 +/-0.0003 in Group caffeine, and 0.0295 +/-0.0069 in Group DDP+caffeine (P <0.01). And the survival time was (33.63 +/-4.63)d in control group, (52.13 +/-11.74)d in Group DDP, (35.63 +/-5.15)d in Group caffeine, and (55.13 +/-16.23)d in Group DDP+caffeine (P <0.01).

CONCLUSIONCaffeine could enhance the anti-tumor effect of cisplatin in rat osteosarcoma.