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Retroviral transduction of intercellular adhesion molecule-1 enhances endothelial attachment of bladder cancer
K Tanabe1, J P Alexander, F Steinbach
1The Cleveland Clinic Foundation, Department of Urology, OH 44195, USA.
Abstract:
An intercellular adhesion molecule-1 (ICAM-1)-negative RT4 transitional cell carcinoma (TCC) cell line was transduced with full-length ICAM-1 cDNA via a retroviral vector. Flow cytometry showed that a sense-oriented clone (S20) highly expressed ICAM-1 while an anti-sense clone (AS6) did not. Both S20 and AS6 bound with equal frequency (30 +/- 8.7% vs 30 +/- 9.4%) to unstimulated human umbilical vein endothelial cells (HUVECs) in cell attachment assays. However, when phorbol myristate acetate (PMA)-activated T lymphocytes, which express lymphocyte function-associated antigen-1 (LFA-1), were cocultured with tumor cells, attachment of S20 increased twofold (60 +/- 11.9%) but AS6 showed no change (32 +/- 11%). Blocking studies with anti-LFA-1 and anti-ICAM-1 monoclonal antibodies caused an inhibition of the attachment to baseline levels, demonstrating that the enhancement of S20 attachment was dependent upon the LFA-1/ICAM-1 interaction. Enhanced attachment of S20 was not inhibited by the addition of isotypic immunoglobulin G. These results suggest that LFA-1-expressing leukocytes may act as a bridge between the endothelium and tumor cells which express ICAM-1 and, thereby, enhance the potential for hematogenous metastasis.
Insights
Leukocytes expressing lymphocyte function-associated antigen-1 (LFA-1) may bridge endothelial cells and tumor cells expressing intercellular adhesion molecule-1 (ICAM-1). This interaction enhances tumor cell attachment, potentially increasing hematogenous metastasis risk.
Area of Science:
- Oncology
- Immunology
- Cell Biology
Background:
- Transitional cell carcinoma (TCC) metastasis involves complex cell interactions.
- Intercellular adhesion molecule-1 (ICAM-1) plays a role in cell adhesion.
- Lymphocyte function-associated antigen-1 (LFA-1) on leukocytes mediates immune cell interactions.
Purpose of the Study:
- To investigate the role of ICAM-1 expression in TCC cell attachment to endothelial cells via leukocyte bridging.
- To elucidate the mechanism of ICAM-1 mediated tumor cell adhesion.
Main Methods:
- Retroviral transduction of ICAM-1 into TCC cells.
- Flow cytometry to confirm ICAM-1 expression.
- Cell attachment assays using tumor cells, endothelial cells, and activated T lymphocytes.
- Blocking studies with monoclonal antibodies against LFA-1 and ICAM-1.
Main Results:
- ICAM-1 expressing TCC cells (S20) showed significantly increased attachment to activated T lymphocytes compared to ICAM-1 negative cells (AS6).
- This enhanced attachment was mediated by the LFA-1/ICAM-1 interaction, as confirmed by blocking antibody studies.
- Leukocyte attachment to tumor cells was specific and not due to non-specific immunoglobulin binding.
Conclusions:
- Leukocytes expressing LFA-1 can act as bridges between ICAM-1 expressing tumor cells and the endothelium.
- The LFA-1/ICAM-1 interaction enhances tumor cell adhesion, suggesting a mechanism for increased hematogenous metastasis.
- Targeting ICAM-1 or LFA-1 interactions could potentially inhibit TCC metastasis.