Colocalization of the p185HER2 oncoprotein and integrin α6β4 in Calu-3 lung carcinoma cells
✍ Scribed by Manuela Campiglio; Elda Tagliabue; Uppugunduri Srinivas; Rita Pellegrini; Stefania Martignone; Sylvie Ménard; Maria Ines Colnaghi; Luciano Lombardi; Pier Carlo Marchisio
- Book ID
- 102877697
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 926 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Anti-pl 85HERZ monoclonal antibodies often show intense reactivity with the basement membrane of tumor cells that overexpress the HER2/neu gene product ( p l 85HERZ). To evaluate a possible interaction between p l 85HERZ and adhesion molecules or their receptors, the polarity of p l 85HERZ was tested in lung carcinoma cell line Calu-3, which overexpresses this protein, in cultures grown as confluent monolayers or as aggregates. MAb immunostaining patterns indicated that ~1 8 5 ~~~ is concentrated on the baso-lateral membrane of cells and that it colocalizes with the integrin a6P4 at the cell-cell junctions where laminin is also found. The same membrane region showed intense reactivity with antiphosphotyrosine antibodies. Furthermore, integrin clustering induced by the specific antibody was accompanied by the clustering of p l 85HERZ, as indicated by immunoelectron microscopy, and by a subsequent increase in p l 85HEU tyrosine phosphorylation. Treatment with exogenous laminin also resulted in increased basal levels of p l 85HER2 phosphorylation. These data suggest a physical interaction between the integrin and the oncoprotein that might be functionally relevant in directly controlling the tyrosine phosphorylation of the catalytic domain of p l 85HER2. D 1994 WiIey-Liss, Inc.