Expression of cell adhesion molecules and connexins in gap junctional intercellular communication deficient human mesothelioma tumour cell lines and communication competent primary mesothelial cells

Our plain-English summary of Expression of cell adhesion molecules and connexins in gap junctional intercellular communication deficient human mesothelioma tumour cell lines and communication competent primary mesothelial cells, by K. Pelin, A. Hirvonen, K. Linnainmaa (Carcinogenesis, 1994).

The study

• Authors: K. Pelin, A. Hirvonen, K. Linnainmaa
• Journal: Carcinogenesis
• Published: 1994;15(11):2673-5
• Cited by: 50 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Gap junctional intercellular communication (GJIC) has been reported to be markedly reduced in human mesothelioma tumour cell lines compared with primary mesothelial cells. Immunofluorescence stainings have shown that the gap junction protein connexin43 (Cx43) is expressed in both malignant and normal mesothelial cells. In this study the mRNA expression of Cx43 and three different connexins--Cx37, Cx40 and Cx45, which are highly expressed in lung tissue--was investigated in eight human mesothelioma cell lines, and in human primary mesothelial cells from several donors. The expression of the intercellular adhesion molecules A-CAM (N-cadherin) and L-CAM (E-cadherin) was studied at the protein level. No mRNA expression of Cx37, Cx40 or Cx45 in either mesothelioma tumour cells or the primary mesothelial cells was detected. Cx43 was expressed at both the mRNA and the protein level, in seven out of eight mesothelioma cell lines, as well as in all the primary mesothelial cell cultures. The well as in all the primary mesothelial cell cultures. The intercellular adhesion molecule A-CAM was expressed at the cell-cell borders in six out of seven mesothelioma cell lines, as well as in normal mesothelial cells. No expression of L-CAM was observed in these cells. The results suggest that Cx43 and A-CAM are the major proteins in gap and adherens junctions respectively in human mesothelial cells. Most mesothelioma tumour cell lines with markedly reduced GJIC still express both Cx43 and A-CAM. Only one of our mesothelioma tumour cell lines severely deficient in GJIC lacks both the gap junction protein Cx43 and the cell adhesion molecule A-CAM.

In plain English

This short report studied cultured human cells, not patients. The authors had earlier found that mesothelioma cell lines communicate poorly through cell-to-cell channels called gap junctions, and looked for reasons. They measured mRNA for four gap junction proteins (connexins) in eight mesothelioma lines and normal mesothelial cells from non-cancerous donors, and stained cells for two adhesion molecules. No mRNA for Cx37, Cx40 or Cx45, connexins common in lung tissue, was detected in any of these cells. Cx43 was found at mRNA and protein level in seven of eight mesothelioma lines and in the normal cells. Of seven mesothelioma lines with adhesion results, six showed A-CAM (N-cadherin) at cell borders, as did normal cells. E-cadherin was not seen. Only one line, M33K, lacked both Cx43 and A-CAM. The authors concluded that Cx43 is the major gap junction protein in these cultured cells and that missing proteins explain poor communication in only one line. No cells were exposed to asbestos. The authors said the role of asbestos fibres remains unsolved and that cultured cells may differ from cells in the body.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study of cultured human cells (short communication), measuring connexin mRNA by RNA blotting and adhesion proteins by immunofluorescence staining
• Who was studied: Eight human mesothelioma tumour cell lines (described in earlier work), GJIC-competent primary mesothelial cells from pleural effusions of non-cancerous donors (five donors for A-CAM staining), and the immortalized human mesothelial cell line MeT-5A; Finnish Institute of Occupational Health, Helsinki
• Exposure: No asbestos exposure was tested in this study. It compared expression of connexins (Cx37, Cx40, Cx45, Cx43) and cadherins (A-CAM/N-cadherin, E-cadherin/L-CAM) between tumour and normal mesothelial cells.
• Main results:
  • No mRNA for Cx37, Cx40 or Cx45 was detected in any of the eight mesothelioma cell lines or in the primary mesothelial cells
  • Cx43 was expressed at mRNA and protein level in seven of eight mesothelioma cell lines, in the primary mesothelial cells and in MeT-5A
  • E-cadherin was not observed in the seven mesothelioma cell lines tested, in MeT-5A, or in the primary mesothelial cells
  • A-CAM was clearly expressed at cell membrane borders in six mesothelioma cell lines, in MeT-5A, and in primary mesothelial cells from five non-cancerous patients
  • Only one mesothelioma line, M33K, which lacked functional GJIC, expressed neither Cx43 nor A-CAM
  • M33K was the only line established from primary tumour tissue of a patient with stage IV disease
• The authors' conclusion: The authors concluded that Cx43 is the major gap junction protein in cultured human mesothelial and mesothelioma cells, and that lack of both Cx43 and A-CAM explains the reduced cell communication in only one mesothelioma line. In their view the role of asbestos fibres remains to be solved.
• Limitations the authors state:
  • Connexin expression in cultured cells may differ from that in the body, because culture conditions can switch connexins on or off
  • The cause of poor communication in lines that express Cx43 and A-CAM, and the role of asbestos, were not established

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Mesothelial Cells.

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