Document Detail

Expression of the integrin alpha5 subunit and its mediated cell adhesion in hepatocellular carcinoma.
MedLine Citation:
PMID:  9292706     Owner:  NLM     Status:  MEDLINE    
Tumor invasion and metastasis are complex processes, requiring the ability of tumor cells to interact with proteins of the extracellular matrix through cell-adhesion molecules on the cell surface. Integrins are heterodimeric membrane glycoproteins, consisting of alpha and beta subunits, which enable cells to recognize adhesive substrates in the extracellular matrix. The roles of the integrin alpha5beta1 in tumor invasion are highlighted by finding that some tumor cells have lost or reduced alpha5beta1 expression. It therefore functions as a negative signaling regulator. Expression of alpha5beta1 and its mediation of cell adhesion in hepatocellular carcinoma (HCC) have not been elucidated. In surgical specimens of HCC we found, by immunohistochemistry and Northern blot analysis, that the alpha5-positive rates in cancerous tissues were lower than the corresponding rates in non-cancerous tissues. Reduced expression of the integrin alpha5 occurred more frequently in HCC with more malignant phenotypes, such as poor differentiation, large size (more than 10-cm in diameter), absence of capsule and high invasion. Reverse transcription/polymerase chain reaction, a more sensitive assay, was used to detect the alpha5 mRNA level in LCID20, a highly metastatic model of human HCC, and LCID35, a low-metastasis model. The results showed that integrin alpha5 was negative in the former and positive in the latter. Cell adhesion assays showed the maximal percentage inhibition of anti-alpha5 mAb on SMMC 7721 cell adhesion to fibronectin to be 68.9 +/- 4.9% at the saturation concentrations of each antibody (200 microg/ml). If anti-alpha5 mAb was combined with anti-beta1 mAb, the inhibition was 74.1 +/- 11.1%. It is concluded that reduced expression of the integrin alpha5 subunit is correlated with more malignant phenotypes of human HCC. Any change in the adhesion of hepatocellular carcinoma cells to fibronectin is mainly dependent upon the function of the integrin alpha5beta1.
M Yao; X D Zhou; X L Zha; D R Shi; J Fu; J Y He; H F Lu; Z Y Tang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cancer research and clinical oncology     Volume:  123     ISSN:  0171-5216     ISO Abbreviation:  J. Cancer Res. Clin. Oncol.     Publication Date:  1997  
Date Detail:
Created Date:  1997-09-30     Completed Date:  1997-09-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7902060     Medline TA:  J Cancer Res Clin Oncol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  435-40     Citation Subset:  IM    
Liver Cancer Institute, Zhong Shan Hospital, Shanghai Medical University, P.R. China.
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MeSH Terms
Antigens, CD / biosynthesis*,  metabolism,  physiology*
Carcinoma, Hepatocellular / metabolism*,  pathology*
Cell Adhesion / physiology
Fibronectins / metabolism
Integrin alpha5
Liver Neoplasms / metabolism*,  pathology*
Neoplasm Metastasis
Polymerase Chain Reaction
RNA, Messenger / metabolism
Receptors, Fibronectin / biosynthesis,  metabolism,  physiology
Tumor Cells, Cultured
Reg. No./Substance:
0/Antigens, CD; 0/Fibronectins; 0/Integrin alpha5; 0/RNA, Messenger; 0/Receptors, Fibronectin

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