Preliminary Study On Anticancer Activities Of Gecko Alcohol Extract

OBJECTIVE: To investigate the proliferation inhibitory effects of Gecko alcohol extract (GAE) and its antitumor mechanism on human esophageal squamous carcinoma EC9706 cells in vitro. To observe the antitumor effects of GAE and its synergism and attenuation effects on CTX in vivo. METHODS: MTT assay was used to analyze the proliferation inhibition effects of the GAE on EC9706 cells. The change of cell morphology was observed through inverted microscope. Morphological change of apoptotic cell was observed by Hoechst33258 fluorescence staining and apoptosis induced by GAE was evaluated in TUNEL assay. The expression of apoptosis protein Bax and Bcl-2 in EC9706 cells was investigated by immunohistochemistry. In vivo, the inhibitory effect of GAE on tumor growth was examined on transplanted model of mice S180. S180-bearing mice were given GAE via intravenous injection, the tumor inhibitory rate and the levels of serum TNF–αof mice were detected. After inoculation of S180 tumor, the synergism and attenuation effects of GAE on CTX were observed. After 12 days of treatment, the tumor inhibitory rate, the count of peripheral white blood cells, index of thymus and spleen were calculated. RESULTS: After GAE (6mg/mL, 6.5mg/mL, 7mg/mL, 7.5mg/mL, 8mg/mL) treatment for 24h, 48h, and 72h, separately, EC9706 cell proliferation was significantly inhibited in both reagent dose- and treatment time-dependent manner (P < 0. 01). The inhibitory rates (6mg/mL,6.5 mg/mL, 7mg/mL, 7.5mg/mL, 8mg/mL) on EC9706 cell were 13%, 23%, 40%, 68%, 76% in 24h, 37%, 56%, 77%, 86%, 88% in 48h, 54%, 71%, 83%, 92%, 93% in 72h. Cell apoptosis in GAE-treated group (6mg/mL, 7mg/mL) was significantly higher than that in control group [(12.73±3.84 , 19.80±2.32) % vs (5.87±2.54) % , P < 0. 05,P < 0. 01] . Although the level of Bcl-2 did not change significantly, the expression of Bax was remarkably up-regulated in GAE-treated group. GAE inhibited the growth of S180 sarcoma in Kun-ming mice at all doses (0.6g/kg, 1.2g/kg, 2.4g/kg) administered. The average tumor inhibitory rates were 44.88%, 63.94% and 69.53%, respectively. However, the levels of serum TNF-αof mice were no change. The tumor inhibitory rates of intravenous administration of GAE(0.6g/kg, 1.2g/kg, 2.4g/kg) combined with CTX (20mg/kg) were 56.93%, 67.15%and 70.24%, which were higher than that of CTX administration alone (41.71%). Compared with those in CTX group, the count of WBC (P<0.01), the index of thymus and spleen (P<0.05) were significantly elevated in all GAE and CTX combination groups. CONCLUSION: In tumor inhibitory test, it is shown that GAE may possess significantly inhibitory effect in vitro and in vivo. Antitumor mechanism of GAE on EC9706 cells can induce cell apoptosis which may be associated with the increased Bax/Bcl-2 ratio in EC9706 cells. GAE has synergism and attenuation effects on CTX.