Crotoxin induces apoptosis and autophagy in human lung carcinoma cells n vitro via activation of the p38MAPK signaling pathway
Abstract
Rong HAN#, Hui LIANG#, Zheng-hong QIN, Chun-yu LIU*
College of Pharmaceutical Science, Soochow University, Suzhou 215123, China
Aim: Crotoxin (CrTX) is the primary toxin in South American rattlesnake (Crotalus durissus terrificus) venom, and exhibits antitumor and other pharmacological actions in vivo and in vitro. Here, we investigated the molecular mechanisms of the antitumor action of CrTX in human lung carcinoma cells in vitro.
Methods: Human lung squamous carcinoma SK-MES-1 cells were tested. The cytotoxicity of CrTX was evaluated in both MTT and colony formation assays. Cell cycle was investigated with flow cytometry. Cell apoptosis was studied with Hoechst 33258 and Annexin V-FITC staining. The levels of relevant proteins were analyzed using Western blot assays.
Results: CrTX (25, 50, 100 μmol/L) inhibited the growth and colony formation of SK-MES-1 cells in dose- and time-dependent manners. CrTX increased the proportion of S phase cells and dose-dependently induced cell apoptosis, accompanied by down-regulating the expression of proliferating cell nuclear antigen (PCNA), and increasing the level of cleaved caspase-3. Furthermore, CrTX dose-dependently increased the expression of autophagy-related proteins LC3-II and beclin 1, and decreased the level of p62 in the cells. Moreover, CrTX (50 μmol/L) significantly increased p38MAPK phosphorylation in the cells. Pretreatment of the cells with SB203580, a specific inhibitor of p38MAPK, blocked the inhibition of CrTX on cell proliferation, as well as CrTX-induced apoptosis and cleaved caspase-3 expression.
Conclusion: The p38MAPK signaling pathway mediates CrTX-induced apoptosis and autophagy of human lung carcinoma SK-MES-1 cells in vitro.
Keywords: human lung carcinoma; snake venom; crotoxin; cell cycle arrest; apoptosis; autophagy; caspase-3; proliferating cell nuclear antigen; p38 MAPK; SB203580
This study was funded by the project of the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)and Suzhou Science and Technology Plan Projects in 2012 (No SYS201205).
# The two authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail liuchunyu@suda.edu.cn
Received 2014-03-09 Accepted 2014-06-05
Keywords:
College of Pharmaceutical Science, Soochow University, Suzhou 215123, China
Aim: Crotoxin (CrTX) is the primary toxin in South American rattlesnake (Crotalus durissus terrificus) venom, and exhibits antitumor and other pharmacological actions in vivo and in vitro. Here, we investigated the molecular mechanisms of the antitumor action of CrTX in human lung carcinoma cells in vitro.
Methods: Human lung squamous carcinoma SK-MES-1 cells were tested. The cytotoxicity of CrTX was evaluated in both MTT and colony formation assays. Cell cycle was investigated with flow cytometry. Cell apoptosis was studied with Hoechst 33258 and Annexin V-FITC staining. The levels of relevant proteins were analyzed using Western blot assays.
Results: CrTX (25, 50, 100 μmol/L) inhibited the growth and colony formation of SK-MES-1 cells in dose- and time-dependent manners. CrTX increased the proportion of S phase cells and dose-dependently induced cell apoptosis, accompanied by down-regulating the expression of proliferating cell nuclear antigen (PCNA), and increasing the level of cleaved caspase-3. Furthermore, CrTX dose-dependently increased the expression of autophagy-related proteins LC3-II and beclin 1, and decreased the level of p62 in the cells. Moreover, CrTX (50 μmol/L) significantly increased p38MAPK phosphorylation in the cells. Pretreatment of the cells with SB203580, a specific inhibitor of p38MAPK, blocked the inhibition of CrTX on cell proliferation, as well as CrTX-induced apoptosis and cleaved caspase-3 expression.
Conclusion: The p38MAPK signaling pathway mediates CrTX-induced apoptosis and autophagy of human lung carcinoma SK-MES-1 cells in vitro.
Keywords: human lung carcinoma; snake venom; crotoxin; cell cycle arrest; apoptosis; autophagy; caspase-3; proliferating cell nuclear antigen; p38 MAPK; SB203580
This study was funded by the project of the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)and Suzhou Science and Technology Plan Projects in 2012 (No SYS201205).
# The two authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail liuchunyu@suda.edu.cn
Received 2014-03-09 Accepted 2014-06-05