Regulation of Akt by EGF-R inhibitors, a possible mechanism of EGF-R inhibitor-enhanced TRAIL-induced apoptosis.
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a type II transmembrane cytokine and a potent inducer of apoptosis. Epidermal growth factor (EGF) signaling is well known to involve in tumor survival and overexpression of EGF receptor (EGF-R) attributes to decreased responsiveness to many available therapies in cancer treatment. We investigated whether EGF-R inhibitors enhance TRAIL-induced apoptosis. We exposed A549 cells to Genistein, PD153035, and PD158780 for 12h and then treated with recombinant TRAIL protein. TRAIL alone induced 25% cell death after a 3-h treatment, but in cells pretreated with EGF-R inhibitors, TRAIL induced cell death to more than 70% after 3h treatment. Genistein enhanced TRAIL-induced apoptosis in a time- and dose-dependent manner. Western blot analyses showed that pretreatment with Genistein down-regulated the protein levels of total Akt and phosphorylated active Akt. Genistein also decreased the protein level of Bcl-XL that is regulated by Akt. These molecules are well characterized to act against induction of apoptotic cell death. Therefore, our data suggest that EGF-R inhibitor may sensitize A549 cells to TRAIL-induced apoptosis by regulating expression of these proteins. EGF-R inhibitors may play an important role in the anti-cancer activity of TRAIL protein, especially in TRAIL-resistant tumors that arise by expressing constitutively active Akt.
Park
Sang-Youel
SY
Department of Surgery, University of Pittsburgh School of Medicine, BST W1513, Pittsburgh, PA 15261, USA.
Seol
Dai-Wu
DW
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D002460:Cell Line; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D019833:Genistein / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000502:physiology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects* / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt; D011743:Pyrimidines / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
C107875:6-(methylamino)pyrido(3,4-d)pyrimidine; D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; D011799:Quinazolines; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha; D019833:Genistein; D066246:ErbB Receptors; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C088860:4-((3-bromophenyl)amino)-6,7-dimethoxyquinazoline