Curcumin Regulates Colon Cancer by Inhibiting P-Glycoprotein in In-situ Cancerous Colon Perfusion Rat Model

Studies on p-glycoprotein was carried out world vide with cell lines like Caco2, MDR1-LLC-PK1 and MDR1-MDCK in-vitro, but most of the results were failed to produce similar results in-vivo. In the present study curcumin inhibitory action on p-glycoprotein increased permeability of irinotecan, so in the colon cancer it would be beneficial if curcumin used as add on therapy.

Intra-rectal administered of N-Nitroso N-methyl urea (2 mg/Kg) induced colon cancer. Single pass whole length of colon in-situ perfusion was carried out in rats with irinotecan to study the influence of p-glycoprotein modulators like verapamil and curcumin. The rats were divided in to 5 groups (n=6), Group I served as control perfused with 30 μg/ml of irinotecan, propronolol and phenol red. Group II was cancerous group, induced by N-methyl N-nitroso urea. Group III was perfused with irinotican in cancerous rats. Group IV, perfused with irinotican in presence of verapamil and group V was pre-treated with curcumin and then perfused with irinotican and was estimated by HPLC-UV to effective permeability coefficient.

Our qRT-PCR and Western blot results confirmed that about 15-fold decreases in the expression of p-glycoprotein (P-gp) in curcumin treated colon cancer cells. Irinotecan was increased to 0.00066 cm/s and about 11-fold increase in verapamil-coperfused group, where curcumin pre-treated group irinotecan was increases 0.00006 cm/s to 0.00042 cm/s that is about 7-fold increase p-glycoprotein inhibitory activity by verapamil and curcumin found to be significantly enhanced the cancerous colon permeability of irinotecan.

Any safe suitable p-glycoprotein inhibitors along with irinotecan will enhance the therapeutic benefit in the treatment of the colon cancer.