Sanguinarine, derived from the root of Sanguinaria canadensis and other poppy fumaria species, possesses strong antimicrobial, anti-inflammatory, and
antioxidant properties. We earlier showed that
sanguinarine kills human
epidermoid carcinoma A431 cells via an induction of apoptosis [N. Ahmad et al., Clin.
Cancer Res., 6: 1524-1528, 2000]. In this study, using immortalized human keratinocytes (HaCaT cells), we provide information about mechanism of the antiproliferative effect of
sanguinarine.
Sanguinarine [0.1 (M-2 (M)] treatment to HaCaT cells was found to inhibit in a dose-dependent manner the cell proliferation and induce apoptosis, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide assay and ELISA, respectively.
Sanguinarine treatment also resulted in a significant cleavage of
poly(ADP-ribose) polymerase in HaCaT cells. Because mitochondrial pathway is critical for the regulation of apoptosis, we studied the involvement and regulation of mitochondrial events in
sanguinarine-mediated apoptosis of HaCaT cells. As shown by the immunoblot analysis, our data clearly demonstrated that
sanguinarine treatment to HaCaT cells resulted in a dose-dependent (a) increase in the level of Bax with a concomitant decrease in Bcl-2 levels and (b) increase in Bax/Bcl-2 ratio.
Sanguinarine also resulted in significant increases in the proapoptotic members of Bcl-2 family
proteins, i.e., Bak and Bid. This was accompanied by increase in (a)
protein expression of
cytochrome c and
apoptotic protease-activating factor-1 and (b) activity and
protein expression of
caspase-3,
caspase-7,
caspase-8, and
caspase-9. Taken together, our data showed the involvement of mitochondrial pathway and Bcl-2 family
proteins during
sanguinarine-mediated apoptosis of immortalized keratinocytes. We suggest that
sanguinarine could be developed as a drug for the management of hyperproliferative skin disorders, including
skin cancer.