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Metastasis-suppressor KAI1/CD82 induces homotypic aggregation of human prostate cancer cells through Src-dependent
Bokeun Jee1, Kideok Jin, Jang-Hee Hahn
1Vascular System Research Center, Division of Life Sciences, College of Natural Sciences, Kangwon National University, Chunchon 200-701, Korea.
Abstract:
To investigate the functional role of KAI1/CD82, a metastasis suppressor for human prostate cancer, in the regulation of homotypic cell adhesion, we transfected KAI1 cDNA into DU 145 human prostate cancer cells and established stable transfectant clones with high KAI1/CD82 expression. The KAI1 transfectant cells exhibited significantly increased homotypic cell aggregation in comparison with the control transfectant cells. This aggregation of the KAI1 transfectants was further enhanced upon exposure to anti-CD82 antibody, suggesting that KAI1/CD82 may be involved in the intracellular signaling for the cell adhesion. Among several signal pathway inhibitors tested, PP1, an inhibitor of Src family kinases, significantly suppressed homotypic aggregation of the KAI1 transfectant cells. Ligation of KAI1/CD82 with anti-CD82 antibody increased endogenous Src kinase activity of the KAI1 transfectant cells. When different types of src expression constructs were retransfected into the KAI1-transfected DU 145 cells, kinase-negative mutant src transfectant cells exhibited much lower homotypic aggregation than the mock cells transfected with an empty vector. Moreover, homotypic aggregation of the mutant src transfectant cells was not enhanced by KAI1/CD82 ligation with anti- CD82 antibody. These results suggest that Src mediates the intracellular signaling pathway of KAI1/CD82 for the induction of homotypic adhesion of human prostate cancer cells.
Insights
KAI1/CD82 enhances prostate cancer cell adhesion by activating Src kinases. This discovery reveals a new signaling pathway for metastasis suppression, crucial for understanding cancer progression.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- KAI1/CD82 is a known metastasis suppressor in human prostate cancer.
- Understanding the molecular mechanisms of KAI1/CD82 in cell adhesion is critical for cancer research.
Purpose of the Study:
- To investigate the role of KAI1/CD82 in regulating homotypic cell adhesion in prostate cancer.
- To elucidate the intracellular signaling pathways involved in KAI1/CD82-mediated cell adhesion.
Main Methods:
- Transfection of KAI1 cDNA into DU 145 prostate cancer cells.
- Assessing homotypic cell aggregation with and without anti-CD82 antibody.
- Utilizing signal pathway inhibitors (e.g., PP1) and Src kinase activity assays.
- Retransfection with different Src expression constructs, including kinase-negative mutants.
Main Results:
- KAI1/CD82 expression significantly increased homotypic cell aggregation.
- Src family kinases, specifically Src, mediate KAI1/CD82's effect on cell adhesion.
- Ligation of KAI1/CD82 activates Src kinase activity, essential for enhanced aggregation.
Conclusions:
- Src kinase acts as a crucial mediator in the KAI1/CD82 signaling pathway for inducing homotypic adhesion in prostate cancer cells.
- This finding provides insights into the anti-metastatic function of KAI1/CD82 and potential therapeutic targets.