ADAM28 is overexpressed in human breast carcinomas: implications for carcinoma cell proliferation through cleavage of insulin-like growth factor binding protein-3.
A disintegrin and metalloproteinases (ADAMs) are involved in various biological events including cell adhesion, cell fusion, membrane protein shedding, and proteolysis. In the present study, our reverse transcription-PCR analysis showed that among the 12 different ADAM species with a putative metalloproteinase motif, prototype membrane-anchored ADAM28m and secreted-type ADAM28s are selectively expressed in human breast carcinoma tissues. By real-time quantitative PCR, their expression levels were significantly higher in carcinomas than in nonneoplastic breast tissues. In situ hybridization, immunohistochemistry, and immunoblotting analyses indicated that ADAM28 is predominantly expressed in an active form by carcinoma cells within carcinoma tissues. A direct correlation was observed between mRNA expression levels and proliferative activity of the carcinoma cells. Treatment of ADAM28-expressing breast carcinoma cells (MDA-MB231) with insulin-like growth factor-I (IGF-I) increased cell proliferation, cleavage of IGF binding protein (IGFBP)-3, as well as IGF-I cell signaling; these processes were all significantly inhibited by treatment with ADAM inhibitor or anti-ADAM28 antibody. Down-regulation of ADAM28 expression in MDA-MB231 cells with small interfering RNA significantly reduced cell proliferation, IGFBP-3 cleavage, and growth of xenografts in mice. In addition, cleavage of IGFBP-3 in breast carcinoma tissues was correlated with ADAM28 expression levels and inhibited by treatment with ADAM inhibitor or anti-ADAM28 antibody. These results show that ADAM28 is overexpressed in an activated form in human breast carcinoma cells and suggest that ADAM28 is involved in cell proliferation through enhanced bioavailability of IGF-I released from the IGF-I/IGFBP-3 complex by selective IGFBP-3 cleavage in human breast carcinomas.
Mitsui
Yoko
Y
Department of Pathology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan.
Mochizuki
Satsuki
S
Kodama
Takahide
T
Shimoda
Masayuki
M
Ohtsuka
Takashi
T
Shiomi
Takayuki
T
Chijiiwa
Miyuki
M
Ikeda
Tadashi
T
Kitajima
Masaki
M
Okada
Yasunori
Y
D051722:ADAM Proteins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014183:Transplantation, Heterologous
D018972:Insulin-Like Growth Factor Binding Protein 3; D019394:Ki-67 Antigen; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D007334:Insulin-Like Growth Factor I; D051722:ADAM Proteins; C410224:ADAM28 protein, human