Cellular distribution, post-translational modification, and tumorigenic potential of human group III secreted phospholipase A(2).
Human group III secreted phospholipase A(2) (sPLA(2)-III) consists of a central group III sPLA(2) domain flanked by unique N- and C-terminal domains. We found that the sPLA(2) domain alone was sufficient for its catalytic activity and for its prostaglandin E(2) (PGE(2))-generating functions in various cell types. In several if not all cell types, the N- and C-terminal domains of sPLA(2)-III were proteolytically removed, leading to the production of the form containing only the sPLA(2) domain, which could be further N-glycosylated at two consensus sites. Immunohistochemistry demonstrated that sPLA(2)-III was preferentially expressed in the microvascular endothelium in human tissues with inflammation, ischemic injury, and cancer. In support of this, sPLA(2)-III was induced in cultured microvascular endothelial cells after stimulation with proinflammatory cytokines. Expression of sPLA(2)-III was also associated with various tumor cells, and colorectal cancer cells transfected with sPLA(2)-III exhibited enhanced PGE(2) production and cell proliferation, which required sPLA(2)-III catalytic activity. When implanted into nude mice, the sPLA(2)-III-transfected cells formed larger solid tumors with increased angiogenesis compared with control cells. Moreover, small interfering RNA for sPLA(2)-III significantly reduced PGE(2) production and proliferation of colorectal cancer cells. Taken together, these results reveal unique cell type-specific processing and N-glycosylation of sPLA(2)-III and the potential role of this enzyme in cancer development by stimulating tumor cell growth and angiogenesis.
Murakami
Makoto
M
Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. mako@pharm.showa-u.ac.jp
Masuda
Seiko
S
Shimbara
Satoko
S
Ishikawa
Yukio
Y
Ishii
Toshiharu
T
Kudo
Ichiro
I
D000256:Adenoviridae / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D016718:Arachidonic Acid / Q000737:chemistry; D001172:Arthritis, Rheumatoid / Q000473:pathology; D015152:Blotting, Northern; D020134:Catalytic Domain; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D054520:Group III Phospholipases A2; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation; D007511:Ischemia / Q000473:pathology; D016086:Lentivirus / Q000378:metabolism; D008168:Lung / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008833:Microcirculation; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009389:Neovascularization, Pathologic; D010741:Phospholipases A / Q000737:chemistry* / Q000502:physiology*; D017354:Point Mutation; D011453:Prostaglandins / Q000737:chemistry; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014594:Uterine Neoplasms / Q000473:pathology
D011453:Prostaglandins; D016718:Arachidonic Acid; D010741:Phospholipases A; D054520:Group III Phospholipases A2; C484163:PLA2G3 protein, human; D006026:Glycoside Hydrolases