title: hPEBP4 resists TRAIL-induced apoptosis of human prostate cancer cells by activating Akt and deactivating ERK1/2 pathways.
abstract: The treatment options available for prostate cancer are limited because of its resistance to therapeutic agents. Thus, a better understanding of the underlying mechanisms of the resistance of prostate cancer will facilitate the discovery of more efficient treatment protocols. Human phosphatidylethanolamine-binding protein 4 (hPEBP4) is recently identified by us as an anti-apoptotic molecule and a potential candidate target for breast cancer treatment. Here we found the expression levels of hPEBP4 were positively correlated with the severity of clinical prostate cancer. Furthermore, hPEBP4 was not expressed in TRAIL-sensitive DU145 prostate cancer cells, but was highly expressed in TRAIL-resistant LNCaP cells, which show highly activated Akt. Interestingly, hPEBP4 overexpression in TRAIL-sensitive DU145 cells promoted Akt activation but inhibited ERK1/2 activation. The hPEBP4-overexpressing DU145 cells became resistant to TRAIL-induced apoptosis consequently, which could be reversed by PI3K inhibitors. In contrast, silencing of hPEBP4 in TRAIL-resistant LNCaP cells inhibited Akt activation but increased ERK1/2 activation, resulting in their sensitivity to TRAIL-induced apoptosis that was restored by the MEK1 inhibitor. Therefore, hPEBP4 expression in prostate cancer can activate Akt and deactivate ERK1/2 signaling, leading to TRAIL resistance. We also demonstrated that hPEBP4-mediated resistance to TRAIL-induced apoptosis occurred downstream of caspase-8 and at the level of BID cleavage via the regulation of Akt and ERK pathways, and that hPEBP4-regulated ERK deactivation was upstream of Akt activation in prostate cancer cells. Considering that hPEBP4 confers cellular resistance to TRAIL-induced apoptosis and is abundantly expressed in poorly differentiated prostate cancer, silencing of hPEBP4 suggests a promising approach for prostate cancer treatment.
authors.affiliation: Institute of Immunology, Zhejiang University, Hangzhou 310031, China.
authors.forename: Hongzhe
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Immunology, Tsinghua University School of Medicine, Beijing 100084, China, and the.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Immunology and National Key Laboratory of Medical Immunology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.affiliation: Institute of Immunology, Zhejiang University, Hangzhou 310031, China.
authors.forename: Jianming
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Institute of Immunology, Zhejiang University, Hangzhou 310031, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Immunology, Zhejiang University, Hangzhou 310031, China; Institute of Immunology, Tsinghua University School of Medicine, Beijing 100084, China, and the; Institute of Immunology and National Key Laboratory of Medical Immunology, Second Military Medical University, Shanghai 200433, China. Electronic address: caoxt@public3.sta.net.cn.
authors.forename: Xuetao
authors.initials: X
authors.lastname: Cao
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D053181:Caspase 8 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D053181:Caspase 8; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D053221:TNF-Related Apoptosis-Inducing Ligand; D014157:Transcription Factors; C505653:TNFSF10 protein, human; C055473:enhancer-binding protein AP-4