With increasing use of plant-derived
cancer chemotherapeutic agents, exploring the antiproliferative effects of
phytochemicals has gained increasing momentum for anticancer drug design. The
dietary phytochemical quercetin, modulates several signal transduction pathways associated with cell proliferation and apoptosis. The present study was undertaken to examine the effect of
quercetin on cell viability, and to determine the molecular mechanism of
quercetin-induced cell death by investigating the expression of Bcl-2 family
proteins (Bcl-2, Bcl-xL, Mcl1, Bax, Bad, p-Bad),
cytochrome C, Apaf-1,
caspases, and
survivin as well as the
cell cycle regulatory proteins (p53, p21,
cyclin D1), and NF-κB family members (p50, p65, IκB, p-IκB-α, IKKβ and
ubiquitin ligase) in human
cervical cancer (HeLa) cells. The results demonstrate that
quercetin suppressed the viability of HeLa cells in a dose-dependent manner by inducing G2/M phase cell cycle arrest and mitochondrial apoptosis through a p53-dependent mechanism. This involved characteristic changes in nuclear morphology,
phosphatidylserine externalization, mitochondrial membrane depolarization, modulation of
cell cycle regulatory proteins and NF-κB family members, upregulation of proapoptotic Bcl-2 family
proteins,
cytochrome C, Apaf-1 and
caspases, and downregulation of antiapoptotic Bcl-2
proteins and
survivin.
Quercetin that exerts opposing effects on different signaling networks to inhibit
cancer progression is a classic candidate for anticancer drug design.