Dihydropyrano[2,3-c]pyrazole-induced apoptosis in lung cancer cells is associated with ROS generation and activation of p38/JNK pathway

Purpose: To investigate the effect of 2,4-dihydropyrano[2,3-c]pyrazole (DHPP) on lung cancer cells, and the associated mechanism. Methods: The effect of DHPP on cell proliferation was measured using sulphorhodamine B (SRB) assay. Apoptosis of cells was determined using Olympus 1x71 inverted microscope connected to FITC and rhodamine filters. Results: DHPP significantly suppressed the proliferation of A549 and H1299 cells at doses of 0.5-8.0 mu M, but did not affect normal cells (MRC5 and BEAS-2B). In DHPP-treated A549 and H1299 cells, caspase-3 activity was markedly enhanced. At 24 h of treatment with 8.0 mu M DUPP, apoptosis in A549 and H1299 cells was increased to 67.89 and 61.35 %, respectively. Phosphorylation levels of JNK-1/2 and p38 in DHPP-treated A549 and H1299 cells were markedly enhanced. The p-ERK-1/2 expressions in DHPP-treated A549 and H1299 cells were suppressed significantly at 24 h. In DHPP-treated A549 and H1299 cells, DCF-fluorescence was increased 10 folds and 8.5 folds, respectively. Pretreatment with FeTMPyP, an antioxidant, effectively alleviated DHPP-induced increase in expressions of p-p38 and p-JNK, and suppression of expression of p-ERK-1/2. In FeTMPyP-pre-treated cells, the DHPP-induced increase in caspase-3 activity was markedly reduced. Conclusion: DHPP selectively inhibits lung cancer cell growth via oxidative stress which subsequently causes cell apoptosis. Moreover, it activates caspase-3 protein and p38/JNK signaling, with simultaneous inactivation of ERK-1/2. Therefore, DHPP has a potential to be developed for the treatment of lung cancer. However; more studies are required to confirm these findings.