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Alterations in cell surface carbohydrate composition of a human colon carcinoma cell line affect adhesion to
W Kemmner1, J Morgenthaler, R Brossmer
1Institut für Biochemie II, Universität Heidelberg, Germany.
Abstract:
The adhesion of HT29 human colon adenocarcinoma cells to different extracellular matrix components was studied. While treatment of the cells with sialidase had no detectable effect on binding to laminin and fibronectin, attachment to collagen IV was decreased. However, additional removal of beta-(1-4)-bound galactose led to significantly reduced binding to all of the substrates, including fibronectin and laminin. Tunicamycin treatment, monitored by lectin-induced aggregation, drastically diminished cell adhesion to laminin and fibronectin, whereas cell binding to collagen IV was not affected. Arg-Gly-Asp (RGD)-related peptides were used to study the adhesion to collagen IV. The results show that a serine-containing RGD-related peptide GRGDSP has virtually no effect on colon carcinoma cell adhesion to type IV collagen. In contrast, when serine was substituted for threonine (GRGDTP) adhesion to collagen IV was strongly inhibited. After incubation of sialidase-treated cells with the threonine-containing peptide adhesion was almost totally blocked. These results demonstrate the existence of both RGD-dependent and carbohydrate-based mechanisms for metastatic human HT29 cell binding to collagen IV.
Insights
Human colon cancer cell adhesion to extracellular matrix involves both carbohydrate interactions and RGD-dependent mechanisms, particularly for collagen IV binding. These findings are crucial for understanding cancer cell metastasis.
Area of Science:
- Cell Biology
- Biochemistry
- Oncology
Background:
- Cell adhesion to the extracellular matrix (ECM) is critical for cellular functions, including cancer metastasis.
- The HT29 human colon adenocarcinoma cell line serves as a model for studying cancer cell-ECM interactions.
Purpose of the Study:
- To investigate the mechanisms underlying HT29 cell adhesion to ECM components like laminin, fibronectin, and collagen IV.
- To elucidate the roles of specific molecular interactions, including carbohydrate moieties and Arg-Gly-Asp (RGD) motifs, in cell adhesion.
Main Methods:
- Treatment of HT29 cells with enzymes (sialidase, tunicamycin) and specific peptides (RGD variants) to probe adhesion mechanisms.
- Assessment of cell binding to immobilized ECM proteins (laminin, fibronectin, collagen IV).
- Monitoring cell aggregation using lectin-induced aggregation assays.
Main Results:
- Sialidase treatment reduced HT29 cell binding to collagen IV but not laminin or fibronectin.
- Removal of beta-(1-4)-bound galactose significantly decreased adhesion to all tested ECM components.
- Tunicamycin treatment inhibited adhesion to laminin and fibronectin but not collagen IV.
- Adhesion to collagen IV was inhibited by a specific RGD peptide (GRGDTP) but not GRGDSP, suggesting RGD-dependent interactions.
- Combined sialidase treatment and GRGDTP peptide incubation almost completely blocked collagen IV adhesion.
Conclusions:
- HT29 cell adhesion to collagen IV involves both RGD-dependent and carbohydrate-mediated mechanisms.
- Distinct adhesion mechanisms are employed for different ECM components, highlighting the complexity of cell-matrix interactions in colon cancer.
- These findings provide insights into the molecular basis of colon cancer cell adhesion and potential therapeutic targets.