Serum withdrawal-induced apoptosis in thyroid cells is caused by loss of fibronectin-integrin interaction

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Anoikis, a form of apoptosis, is triggered by the loss of cell adhesion to the extracellular matrix in certain cell types.
• Serum withdrawal can induce programmed cell death in various thyroid cell lines.
• The role of the extracellular matrix in serum withdrawal-induced apoptosis in normal human thyroid cells requires investigation.

Purpose of the Study:

• To determine the role of the extracellular matrix in serum withdrawal-induced apoptosis in normal human thyroid cells in primary culture.
• To investigate the mechanism by which serum withdrawal affects cell-matrix adhesion and subsequent apoptosis.

Main Methods:

• Primary human thyroid cells were cultured under serum-stimulated and serum-deprived conditions.
• Production and deposition of insoluble fibronectin (FN) were assessed.
• Cell adhesion was evaluated based on integrin-FN interactions.
• Apoptosis was quantified using DNA fragmentation and annexin V staining.
• The effect of exogenous immobilized FN on apoptosis was examined.

Main Results:

• Serum stimulation induced selective production and deposition of insoluble fibronectin (FN) by thyroid cells.
• Cell adhesion in the presence of serum relied on integrin-FN interactions.
• Serum withdrawal led to degradation of deposited FN and cell detachment.
• Cells undergoing detachment and FN degradation exhibited anoikis, confirmed by DNA fragmentation and annexin V staining.
• Supplementation with exogenous immobilized FN prevented serum withdrawal-induced apoptosis.

Conclusions:

• Serum withdrawal triggers apoptosis in normal human thyroid cells.
• This apoptosis is mediated by the degradation of fibronectin and subsequent loss of cell-matrix adhesion.
• Fibronectin plays a crucial role in maintaining thyroid cell survival under serum-deprived conditions.