Background: Oral cancer constitutes approximately 25% of all cancer types. 7, 12-dimethylbenz (a) anthracene (DMBA) has been widely used as an active chemical inducer for mammary carcinogenesis. COX-2 enzyme is frequently found in certain types of cancer, including colon, lung, breast, pancreas, head, and neck cancers and is usually associated with poor prognosis and short survival. Mushrooms contain polysaccharides that are thought to inhibit tumor growth and viral infection by stimulating immune cells.
Objective: The present work aimed to investigate the effect of mushroom extract on DMBA-induced lip carcinogenesis in albino rats and correlate the results with COX-2 tissue expression.
Materials and methods: Thirty-six adult female albino ratswere divided into three groups as follows (twelve rats each); Group 1: (–ve control group in which each rat was given 1 ml sesame oil via gastric gavage as a single weekly dose for 6 weeks). Group 2: DMBA (+ve control group in which each rat was given DMBA emulsion via gastric gavage as a single weekly dose for 6 weeks). Group 3: DMBA+M (Experimental group in which each rat was given DMBA emulsion for 3 weeks and was co-administered with mushroom extract (dissolved in distilled water) for the following 3 weeks via gastric gavage. Lip specimens were processed for hematoxylin and eosin staining and immunohistochemically prepared for COX-2 expression. The area fraction expressed by COX-2 was calculated histomorphometrically. The data was expressed statistically as mean ± standard deviation (S.D.).
Results: Both mucous membrane and skin side of Group 2 specimens showed signs of basement membrane rupture as well as hyperchromatic, pleomorphic and dysplastic epithelial cells. Connective tissue showed invasionwith dysplastic epithelial cells, dilated and congested blood vessels with many inflammatory cells. However, the mucous membrane side Group 3 exhibited almost intact basement membrane and only few hyperchromatic epithelial cells. The connective tissue displayed less inflammatory cell infiltration with almost absent invasion while, skin side of Group 3 presented some epithelial areas with intracellular edema but apparently minimal invasion of epithelial cells in the dermal connective tissue.
The immunoexpression pattern of COX-2 in both mucous membrane and skin side of Group 2 was clear and strongly positive in epithelial and connective tissue cells. However, Group 3 showed down regulated expression of COX-2.Statistical results presented a significantly reduced expression of COX-2 in Group 1 followed by Group 3, while the highest expression was shown in Group 2.
Conclusion: Mushroom extract is a possible natural source that may limit the carcinogenic effect of a known carcinogenic agent by suppressingits inflammatory reaction and invasive power.