Background: Multidrug Resistance (MDR) is a serious hindrance to cancer chemotherapy
and profoundly influences the clinical findings. Many Traditional Chinese Medicines (TCM) have
been tested with the aim of developing effective resistance modulators or anticancer drugs to overcome
the MDR of human cancers.
Methods: The anticancer effect of baicalin on multidrug-resistant MC3/5FU (5-fluorouracil) cells
was investigated by MTT test and xenografts in nude mice. Cell apoptosis was studied by transmission
electron microscopy, Hoechst-33342 staining, DNA fragmentation detection, and flow cytometry.
RT-PCR and Rhodamine 123 efflux assay was also used to detect its effect on ABC drug transporter
proteins, ABCB1 (P-glycoprotein, P-gp) and ABCC1 (multidrug resistance protein 1, MRP1).
Results: The results indicate that there was no significant effect of baicalin on ABC transporters
expression or efflux function, although it induced potent growth inhibition in MC3/5FU cells. Flow
cytometry, Hoechst 33342 staining and transmission electron microscope revealed that baicalin
caused MC3/5FU cell death through the induction of apoptosis. It is demonstrated that baicalininduced
apoptosis could be mediated by up-regulation of Bax and caspase-3 protein levels and downregulation
of Bcl-2 protein levels. In addition, daily intraperitoneal injection of baicalin (100 and 200
mg/kg) for 2 weeks significantly inhibited the growth of MC3/5FU cells xenografts in nude mice.
Conclusions: Our results suggest that baicalin possesses considerable cytotoxic activity in multidrug
resistance MC3/5FU cells in vitro and in vivo.