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Protein kinase C-alpha activity inversely modulates invasion and growth of intestinal cells
E Batlle1, J Verdú, D Domínguez
1Unitat de Biologia Cel.lular i Molecular, Institut Municipal d'Investigació Mèdica, Calle Dr. Aiguader 80, 08003 Barcelona, Spain.
Abstract:
The phorbol ester phorbol 12-myristate 13-acetate induces remarkable phenotypic changes in intestinal HT-29 M6 cells; these changes consist of loss of homotypic adhesion and inactivation of E-cadherin. In parallel, cell growth is retarded. We have transfected HT-29 M6 cells with an activated form of the conventional protein kinase Calpha (cPK-Calpha). Expression of this isoform induced the acquisition of a scattered phenotype, similar to that adopted by cells after addition of phorbol 12-myristate 13-acetate, with very low cell-to-cell aggregation and undetectable levels of functional E-cadherin. These cell clones were highly motile and rapidly invaded embryonic chick heart fragments. Furthermore, cells expressing activated-cPK-Calpha showed decreased proliferation in comparison to control clones. We have also studied how these two apparently antagonistic changes affect the tumorigenic ability of HT-29 M6 cells. When the different cell clones were xenografted into athymic mice, the effect on cell growth seemed to predominate. Expression of activated-cPK-Calpha significantly reduced the size of the tumors; the cells with the highest level of expression did not even form subcutaneous tumors. Besides their smaller size, the morphology of these tumors was clearly different from those originated by HT-29 M6 cells, and they could be defined as infiltrative on anatomo-pathological basis. These results indicate that cPK-Calpha controls both cell-to-cell adhesion and proliferation of intestinal cells.
Insights
Protein kinase Calpha (cPK-Calpha) activation in intestinal cells disrupts cell adhesion and reduces tumor growth. This protein kinase controls both cell-to-cell adhesion and proliferation in intestinal cells, impacting their tumorigenic potential.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Phorbol ester (phorbol 12-myristate 13-acetate) induces phenotypic changes in HT-29 M6 intestinal cells, including loss of cell adhesion and E-cadherin inactivation.
- These changes are accompanied by a retardation in cell growth.
Purpose of the Study:
- To investigate the role of activated protein kinase Calpha (cPK-Calpha) in modulating intestinal cell phenotype, adhesion, proliferation, and tumorigenicity.
- To understand how cPK-Calpha influences cell-to-cell adhesion and growth in HT-29 M6 cells.
Main Methods:
- Transfection of HT-29 M6 cells with an activated form of cPK-Calpha.
- Assessment of cell phenotype, cell-to-cell aggregation, E-cadherin levels, cell motility, and invasion assays.
- Xenotransplantation of transfected cells into athymic mice to evaluate tumorigenic potential.
Main Results:
- Expression of activated cPK-Calpha induced a scattered cell phenotype, reduced cell aggregation, and undetectable E-cadherin levels, similar to phorbol ester treatment.
- Cells expressing activated cPK-Calpha exhibited increased motility and invasiveness.
- Tumorigenicity studies showed that activated cPK-Calpha significantly reduced tumor size, with high expression levels preventing tumor formation.
- Tumors derived from cPK-Calpha expressing cells were smaller and infiltrative in nature.
Conclusions:
- Activated cPK-Calpha plays a critical role in controlling both cell-to-cell adhesion and proliferation of intestinal cells.
- cPK-Calpha influences the metastatic potential and tumorigenicity of intestinal cells, with reduced proliferation and altered adhesion contributing to decreased tumor growth.