Anti-tumor Effect of Combined Betacarotene with X-irradiation in the Mouse Fibrosarcoma : Cytotoxicity and Tumor Growth Delay

Kwon, Hyoung Cheol; Yang, Moon Sik

Abstract

PURPOSE
To investigate whether combined beta-carotene with X-irradiation has more enhanced radition response than X-irradiation or not, we performed a experiment about in vitro cytotoxicity of beta-carotene and/or X-irradiation in the fibrosarcoma cells, tumor growth delay of combined beta-caroten with/or X-irradiation in the mouse fibrosarcoma.
MATERIALS AND METHODS
2% emulsion of beta-carotene was serially diluted and used. X-irradiation was given by 6 MeV linear accelerator. The cytotoxicity of beta-carotene in vitro was evaluated from clonogenic assay. To compare the cytotoxicity between combined beta-carotene with X-irradiation and X-irradiation group, 2 mg/ml of beta-carotene was contacted to fibrosarcoma (FSaII) cells for 1 hour before X-irradiation. For the tumor growth delay, single 20 Gy was given to FSaII tumor bearing C3H/N mice whic was classified as beta-crotene with X-irradiation group (n=6) and X-irradiation alone group (n=5). 0.2 ml of 20 mg/kg of beta-carotene were i.p. injected to mice 30 minute before X-irradiation in the beta-crotene with X-irradiation group. The tumor growth delay defined as the time which reach to 1,000 mm3 of tumor volume. RESULT: (1) Cytotoxicity in vitro; 1) survival fraction at beta-carotene concentration of 0.002, 0.02, 0.2 and 2 mg/ml were 0.69+/-0.07, 0.59+/-0.08, 0.08+/-0.008 and 0.02+/-0.006, respectively. 2) each survival fraction at 2, 4, 6 and 8 Gy in the 2 mg/ml of beta-carotene + X-irradiation group were 0.13+/-0.05, 0.03+/-0.005, 0.01+/-0.002 and 0.009+/-0.0008, respectively. But each survival fraction at same irradiation dose in the X- irradiation group were 0.66+/-0.05, 0.40+/-0.04, 0.11+/-0.01 and 0.03+/-0.006, respectively( p<0.05). (2) The time which reach to 1,000 mm3 of tumor volume of beta-carotene + X-irradiation group and X-irradiation alone group were 18, 19 days, respectively( p>0.05).
CONCLUSION
The contact of beta-caroten to FSaII cells showed mild cytotoxicity which was increased according to concentration. The cytotoxicity of combined beta-carotene with X-irradiation more increased than that of X-irradiation, additionaly. And there was significant difference of cytotoxicity between two groups. But there were no significant difference of the growth delay of fibrosarcoma between two groups.