CD9-mediated activation of the p46 Shc isoform leads to apoptosis in cancer cells.
CD9, a member of the tetraspanin family, has been shown to be involved in a range of cellular activities, including migration, proliferation and adhesion, but the molecular mechanisms by which it mediates such events is unclear. Here, we found that anti-CD9 monoclonal antibody ALB6 inhibited cell proliferation, reduced cell viability and induced not only morphological changes specific to apoptosis but also molecular changes, as evidenced by TUNEL and annexin-V staining. For the possible mechanism of ALB6-induced apoptosis, ALB6 activated the c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 mitogen-activated-protein kinase (MAPK) within 5-15 minutes, as well as caspase-3 within 24-48 hours. It is noteworthy that ALB6 induced tyrosine phosphorylation of the p46 Shc isoform specifically and that the overexpression of its dominant-negative form completely suppressed the ALB6-induced activation of JNK/SAPK, p38 MAPK and caspase-3, resulting in the inhibition of apoptotic cell death. These results suggest that CD9 might regulate apoptosis through the specialized signals in human cancer cell lines.
Murayama
Yoko
Y
Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, 2-2 B5, Yamadaoka, Suita 565-0871, Japan. yokom@imed2.med.osaka-u.ac.jp
Miyagawa
Jun-ichiro
J
Oritani
Kenji
K
Yoshida
Hitoshi
H
Yamamoto
Katsumi
K
Kishida
Osamu
O
Miyazaki
Tamana
T
Tsutsui
Shusaku
S
Kiyohara
Tatsuya
T
Miyazaki
Yoshiji
Y
Higashiyama
Shigeki
S
Matsuzawa
Yuji
Y
Shinomura
Yasuhisa
Y
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry*; D017304:Annexin A5 / Q000494:pharmacology; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000378:metabolism / Q000502:physiology*; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D004396:Coloring Agents / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D020287:In Situ Nick-End Labeling; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D008856:Microscopy, Fluorescence; D009369:Neoplasms / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D060245:Tetraspanin 29; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D017304:Annexin A5; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554869:CD9 protein, human; D004396:Coloring Agents; D008562:Membrane Glycoproteins; D020033:Protein Isoforms; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D060245:Tetraspanin 29; D048051:p38 Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D013936:Thymidine