01.03.2013 | Original Paper | Ausgabe 1/2013
Sensitization of lung cancer cells to cisplatin by β-elemene is mediated through blockade of cell cycle progression: antitumor efficacies of β-elemene and its synthetic analogs
- Q. Quentin Li, Gangduo Wang, Furong Huang, Jueli M. Li, Christopher F. Cuff, Eddie Reed
The development of effective agents for overcoming platinum chemoresistance in lung carcinoma continues to have high priority. We have demonstrated recently that β-elemene, a novel antitumor compound, enhances cisplatin activity by triggering lung cancer cell death via apoptosis. Here, we investigated whether β-elemene acts synergistically with cisplatin to inhibit non-small cell lung cancer (NSCLC) cell proliferation by blocking cell cycle progression. β-Elemene substantially increased the suppressive effect of cisplatin on cell growth and proliferation in the NSCLC cell lines H460 and A549. Furthermore, β-elemene augmented cisplatin in the cell cycle arrest of NSCLC cells at G2/M. This was associated with upregulated checkpoint kinase (CHK2) expression and reduced CDC2 activity (i.e., increased phosphorylation of CDC2 on Tyr-15 and decreased phosphorylation of CDC2 on Thr-161). Moreover, β-elemene and cisplatin in combination clearly decreased the protein levels of cyclin B1 and CDC25C and increased the levels of p21Cip1/Waf1, p27Kip1, and GADD45 in these cells, compared with the effects of either agent alone at the same concentration. These results suggest that the β-elemene-enhanced inhibitory effect of cisplatin on lung carcinoma cell proliferation is regulated by a CHK2-mediated CDC25C/CDC2/cyclin B1 signaling pathway and leads to the blockade of cell cycle progression at G2/M. A comparison of the cytotoxic efficacies of β-elemene and three synthetic analogs (β-elemenol, β-elemenal, and β-elemene fluoride) in the two lung cancer cell lines revealed that β-elemenol and β-elemene fluoride had the same antitumor efficacy as β-elemene, whereas β-elemenal was appreciably more potent than β-elemene. Thus, although all three synthetic analogs of β-elemene considerably suppressed NSCLC cell growth and proliferation, β-elemenal may have greater potential as an anticancer alternative to β-elemene in treating lung cancer and other tumors.