The preventive effect of salvianolic acid B on malignant transformation of DMBA-induced oral premalignant lesion in hamsters

Salvia miltiorrhiza (SM) has been used clinically in Asian countries to improve the microcirculation in the human body. Salvianolic acid B (Sal B), a pure compound extracted from SM, has been reported to be effective against fibrosis and ischemia-reperfusion injury, possibly through its anti-lipid peroxidation action. But the effect of Sal B on oral premalignant lesion and oral carcinogenesis remains unexplored. It is our interest to investigate the chemopreventive effect of Sal B on 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral carcinogenesis in hamsters with respect to angiogenesis. Seventy male Syrian golden hamsters were randomly divided into five groups, with two of 20 and three of 10. DMBA solution (0.5% in acetone) was applied topically to the left cheek pouch of male Syrian golden hamsters in Groups A and B, while animals in Group C were painted with acetone, three times a week for 6 weeks. For the next 18 weeks, animals in Groups B and D received Sal B daily (10 mg/kg body wt/day) by gavage, animals in Groups A and C received same volume of saline. Animals in Group E received no treatment and served as blank control. At the end of the experiment, animals were killed and tissue samples were collected for histopathological and immunohistochemical examinations. The results showed that Sal B significantly decreased the squamous cell carcinoma (SCC) incidence from 64.7 (11/17) to 16.7% (3/18) P = 0.004); angiogenesis was inhibited in dysplasia and SCC (P < 0.01), with a simultaneous decrease in the immunostaining of hypoxia-inducible factor 1_α and vascular endothelium growth factor protein (P < 0.05). The results suggested that Sal B had inhibitory effect against the malignant transformation of oral precancerous lesion and such inhibition may be related to the inhibition of angiogenesis.