Sp1 is involved in H2O2-induced PUMA gene expression and apoptosis in colorectal cancer cells.
BACKGROUND
Reactive oxygen species (ROS) are intricately involved in tumor progression through effects on proliferation, apoptosis and metastasis. But how ROS works is not well understood. In previous study, we found PUMA (p53-upregulated modulator of apoptosis) played an important role in oxaliplatin-induced apoptosis. In the present study, we detect the role of PUMA in H2O2-induced apoptosis in colorectal cancer cells and investigate the potential mechanism.


RESULTS
We showed that H2O2 stimulated the activity of a 493 PUMA promoter reporter gene construct. Suppressing the expression of PUMA abrogated H2O2-induced apoptosis. Deletion of the Sp1-binding sites also decreased the transactivation of PUMA promoter by H2O2. Furthermore, induction of PUMA promoter activity by H2O2 was abrogated by PFT-alpha (a p53 inhibitor) and Mithramycin A (a Sp1 inhibitor), as compared with PFT-alpha alone. To determine the effects of Sp1 on PUMA in H2O2-induced apoptosis, procaspase 3, procaspase 9 and procaspase 8 expression was assessed. Mithramycin A and PFT-alpha also reduced H2O2-induced apoptosis synergistically and abrogated the expression of procaspase 3 and procaspase 9.


CONCLUSIONS
Our findings suggest that PUMA plays a role in H2O2-induced apoptosis, and that Sp1 works together with p53 in the regulation of H2O2-induced PUMA expression and apoptosis in colorectal cancer cells. This study provides important regulatory insights in the mechanisms of ROS in colorectal cancer.
Wang
Xinying
X
Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, PR China. sunwingwxy@163.com
Wang
Jing
J
Lin
Shiyong
S
Geng
Yan
Y
Wang
Jide
J
Jiang
Bo
B
D017209:Apoptosis / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation
D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D016877:Oxidants; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D016329:Sp1 Transcription Factor; D016159:Tumor Suppressor Protein p53; D006861:Hydrogen Peroxide