title: p38 MAPK activation, JNK inhibition, neoplastic growth inhibition, and increased gap junction communication in human lung carcinoma and Ras-transformed cells by 4-phenyl-3-butenoic acid.
abstract: Human lung neoplasms frequently express mutations that down-regulate expression of various tumor suppressor molecules, including mitogen-activated protein kinases such as p38 MAPK. Conversely, activation of p38 MAPK in tumor cells results in cancer cell cycle inhibition or apoptosis initiated by chemotherapeutic agents such as retinoids or cisplatin, and is therefore an attractive approach for experimental anti-tumor therapies. We now report that 4-phenyl-3-butenoic acid (PBA), an experimental compound that reverses the transformed phenotype at non-cytotoxic concentrations, activates p38 MAPK in tumorigenic cells at concentrations and treatment times that correlate with decreased cell growth and increased cell-cell communication. H2009 human lung carcinoma cells and ras-transformed rat liver epithelial cells treated with PBA showed increased activation of p38 MAPK and its downstream effectors which occurred after 4 h and lasted beyond 48 h. Untransformed plasmid control cells showed low activation of p38 MAPK compared to ras-transformed and H2009 carcinoma cells, which correlates with the reduced effect of PBA on untransformed cell growth. The p38 MAPK inhibitor, SB203580, negated PBA's activation of p38 MAPK downstream effectors. PBA also increased cell-cell communication and connexin 43 phosphorylation in ras-transformed cells, which were prevented by SB203580. In addition, PBA decreased activation of JNK, which is upregulated in many cancers. Taken together, these results suggest that PBA exerts its growth regulatory effect in tumorigenic cells by concomitant up-regulation of p38 MAPK activity, altered connexin 43 expression, and down-regulation of JNK activity. PBA may therefore be an effective therapeutic agent in human cancers that exhibit down-regulated p38 MAPK activity and/or activated JNK and altered cell-cell communication.
authors: Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Mercer University, Atlanta, Georgia 30341, USA. matesic_df@mercer.edu
authors: Diane F
authors: DF
authors: Matesic
authors: Tatyana S
authors: TS
authors: Sidorova
authors: Timothy J
authors: TJ
authors: Burns
authors: Allison M
authors: AM
authors: Bell
authors: Paul L
authors: PL
authors: Tran
authors: Randall J
authors: RJ
authors: Ruch
authors: Sheldon W
authors: SW
authors: May
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002450:Cell Communication / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018031:Connexin 43 / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D017629:Gap Junctions / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D018031:Connexin 43; D005229:Fatty Acids, Monounsaturated; D007093:Imidazoles; D011725:Pyridines; C064180:4-phenyl-3-butenoic acid; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580