As2O3-induced c-Src/EGFR/ERK signaling is via Sp1 binding sites to stimulate p21WAF1/CIP1 expression in human epidermoid carcinoma A431 cells.
Arsenic has been effectively used to treat acute promyelocytic leukemia, and can induce cell cycle arrest or apoptosis in human solid tumors. Previously, we have demonstrated that As2O3 can induce p21WAF1/CIP1 (p21) expression in A431 cells and then due to cellular cytotoxicity. Presently, we have clarified these signaling events and compared them with EGF. Using reporter assay, RT-PCR and Western blotting, we show that c-Src activation might be a prerequisite for As2O3-induced EGFR/Ras/Raf/ERK signaling. Furthermore, with the aids of 5'-deletion and site-directed mutagenesis, we demonstrate that Sp1 binding sites, ranging from -64 to -84 bp, are essential for As2O3- or EGF-regulated p21 expression. Finally, our experiments utilizing cycloheximide prompt the suggestion that the stability of mRNA or protein also contributes to As2O3- or EGF-induced p21 expression. Taken together, we conclude that the Sp1 binding sites are required for As2O3-induced p21 gene transcription through c-Src/EGFR/Ras/Raf/ERK pathway. Furthermore, post-transcriptional or post-translational stabilization mechanism is also essential for As2O3-induced p21 expression. EGF-induced p21 expression may involve similar mechanisms as those that operate in the As2O3-mediated reactions in A431 cells.
Liu
Zi-Miao
ZM
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Huang
Huei-Sheng
HS
D000970:Antineoplastic Agents / Q000494:pharmacology*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001665:Binding Sites; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D010087:Oxides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D015533:Transcriptional Activation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000970:Antineoplastic Agents; D001152:Arsenicals; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D010087:Oxides; D016329:Sp1 Transcription Factor; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D016392:Proto-Oncogene Proteins pp60(c-src); D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048055:Mitogen-Activated Protein Kinase 8; D048051:p38 Mitogen-Activated Protein Kinases; D000077237:Arsenic Trioxide