| Summary: | <p>Abstract</p> <p>Background</p> <p>Multidrug resistance (MDR) is a phenomenon that is often associated with decreased intracellular drug accumulation in patient's tumor cells resulting from enhanced drug efflux. It is related to the overexpression of a membrane protein, P-glycoprotein (Pgp-170), thereby reducing drug cytotoxicity. A variety of studies have tried to find MDR modulators which increase drug accumulation in cancer cells.</p> <p>Methods</p> <p>In this study, natural curcuminoids, pure curcumin, demethoxycurcumin and bisdemethoxycurcumin, isolated from turmeric (<it>Curcuma longa </it>Linn), were compared for their potential ability to modulate the human <it>MDR-1 </it>gene expression in multidrug resistant human cervical carcinoma cell line, KB-V1 by Western blot analysis and RT-PCR.</p> <p>Results</p> <p>Western blot analysis and RT-PCR showed that all the three curcuminoids inhibited <it>MDR-1 </it>gene expression, and bisdemethoxycurcumin produced maximum effect. In additional studies we found that commercial grade curcuminoid (approximately 77% curcumin, 17% demethoxycurcumin and 3% bisdemthoxycurcumin) decreased <it>MDR-1 </it>gene expression in a dose dependent manner and had about the same potent inhibitory effect on <it>MDR-1 </it>gene expression as our natural curcuminoid mixtures.</p> <p>Conclusion</p> <p>These results indicate that bisdemethoxycurcumin is the most active of the curcuminoids present in turmeric for modulation of <it>MDR-1 </it>gene. Treatment of drug resistant KB-V1 cells with curcumin increased their sensitivity to vinblastine, which was consistent with a decreased <it>MDR-1 </it>gene product, a P-glycoprotein, on the cell plasma membrane. Although many drugs that prevent the P-glycoprotein function have been reported, this report describes the inhibition of MDR-1 expression by a phytochemical. The modulation of MDR-1 expression may be an attractive target for new chemosensitizing agents.</p>
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