A novel podophyllotoxin derivative (YB-1EPN) induces apoptosis and down-regulates express of P-glycoprotein in multidrug resistance cell line KBV200.

Our group synthesized a new potent anti-tumor podophyllotoxin derivative, YB-1EPN. In our study, we found that it was more potent than etoposide (VP-16). Interestingly, we found that the KBV200 cell line and K562/A02 cell line were rendered resistant towards VP-16 but not towards YB-1EPN. In vitro, both the cytotoxicity of YB-1EPN and its ability to inhibit KBV200 and K562/A02 cells were determined by MTT assay and growth curve. The IC(50) value of YB-1EPN on KBV200 cell was (2.52+/-0.28)microM in contrast to VP-16 (10.1+/-0.220)microM. And YB-1EPN showed a dose-dependent and broad-spectrum antiproliferative activity. Inducing apoptosis by YB-1EPN in KBV200 was assessed by various morphological and biochemical characteristics, including cell shrinkage, chromatin condensation, membrane blebbing, formation of apoptotic bodies, and DNA ladder formation. Rates of apoptosis and cell cycle were also checked through flow cytometry. Reverse transcription-polymerase chain reaction(RT-PCR) was used to detect mdr-1,p53,bcl-2,and bax gene expression. Western-blot assay was used to assess P-glycoprotein (P-gp) expression. We found that YB-1EPN could down-regulate expression level of the mdr-1, bcl-2, and up-regulate expression level of p53, and bax mRNA, as compared to the control. These results suggest that YB-1EPN has the potentiality to overcome P-glycoprotein-mediated multidrug resistance in the KBV200 cell line.