Objective   To study inhibitory effects of gallic acid (GA) on human neuroblastoma xenograft model

and its synergistic effect with chemotherapy.    Methods   A total of 40 3-week-old immuno-competent C57BL/6j mice were transplanted with SK-N-SH cells to established xenograft model

and then randomly divided into 4 groups

10 of each

PBS control group (0.5 ml PBS

i.p

as a negative control)

GA group (250 mg/kg

i.p.

every other day

for 2 continuous weeks)

cyclophosphamide (CP) group (75 mg/kg

i.p.

twice a week

for 2 weeks

as a positive control)

and CP plus GA group (GA and CP were independently administered with same dose and time as above). The relative tumor volume (RTV) was monitored weekly with growth curves. The average weight of the imsplanted tumors and the tumor inhibitory rate (IR) were tested at 21st day after transplantation. Tumor cell proliferation was detected by bromouracil deoxyriboside labeling (BrdU).    Results   The average weight of the transplanted tumors in the GA

CP

and CP plus GA groups were 4 559.0±677.7

2 117.0±749.6

and 637.7±319.6 mg respectively

and the average IR were 36.94%

70.72%

and 91.18%

respectively. Significant difference was observed in average tumor weight in these 3 groups compareel with the PBS group (P0.01)

and between the CP plus GA group and the CP group (P0.01). Tumor proliferation index (LI) were 0.122 9±0.021 9

0.107 6±0.015 6

and 0.041 3±0.013 0

respectively in the tumor tissues of GA

CP

and CP plus GA groups

significant higher than that of the PBS group (0.230 8±0.075 9

P0.01). LI of the mice with CP plus GA treatment was significantly smaller than that treated by CP or GA (P0.01).    Conclusion   GA can inhibit tumor proliferation

and exert synergistic effect with CP to suppress the growth of human neuroblastoma xenograft.