Effect of garlic on tumor invasion and metastatic potential in induced colon carcinogenesis in rats: histopathological and immunohistochemical study

ABSTRACT

Preventive intervention of colorectal cancer has become essential as a major portion of the population may develop the disease at some points during their lives. Diet and nutrition play an important role during this multi-step colon carcinogenic process. Inhibitory activity of garlic was tested on Dimethylhydrasin [DMH] induced colon carcinogenesis in Sprague-Dawley rats. Experimental study was done to investigate the mechanism of garlic action on occurrence of colon neoplasia and liver metastasis as well as the expression of cyclooxygenase-2 [COX-2], matrix metalloproteinase [MMP-2] and CD34 was analyzed in the colonic mucosa. On histopathological examination of colon and liver of the investigated animals, the first [normal control] as well as the fourth group [receiving garlic only] revealed no pathological lesions. In the 2nd group [taking DMH only], colon neoplasia was detected in 21/21 [100%] of animals and liver metastasis in 10/21 [47.6%] while, in the 3rd group [receiving DMH and garlic], the tumor occurrence was detected in 16/32 [50%] of animals with no liver metastasis. Following treatment with garlic, significant suppression of COX-2, MMP-2 expressions [p<0.01] was detected with respect to the carcinogen group. As regards angiogenesis in DMH treated animals, CD34 expression was mostly of grades III and IV compared to grades 1 and II in combined DMH and garlic treated group. It could be concluded that the observed modulatory influences of garlic at the level of suppression of COX-2, MMP-2 and CD34 during DMH induced colon carcinogenesis suggest that the dietary intake of garlic has a chemopreventive and inhibitory effects through the multi-step carcinogenesis