Induction of anoikis by sodium arsenite in rat hepatoma FGC4 cells: comparison with cadmium chloride and implications for assessment of regulation of heat shock protein 70

Abstract

Context: Arsenic, a toxic metalloid with major health concerns, elicits upregulation of heat shock protein 70 (HSP70) in rat hepatoma FGC4 cells, together with evidence of detachment of viable cells from the growth substratum.

Objective: To determine if this cell detachment was linked to anoikis, and the impact of this on measurement of HSP70 expression.

Materials and methods: FGC4 cells were exposed to sodium arsenite, and detached and attached cells were taken for assessment of cell viability, activation of procaspase-3, and expression of HSP70.

Results: Exposure to sodium arsenite led to loss of viable cells from the substratum, associated with apoptosis in detached, but not attached, cells. Upregulation of HSP70 of a similar magnitude was demonstrated in both cell populations. Exposure of cells to cadmium chloride, a toxic metal, also of major environmental concern and believed to act by an oxidative stress mechanism, produced very little release of viable cells from the culture substratum, was not associated with apoptosis, but did elicit a modest upregulation of HSP70 in both cell populations.

Discussion: Exposure of FGC4 cells to sodium arsenite elicits anoikis, a form of anchorage-dependent apoptosis, and assessment of the level of HSP70 upregulation in such cells should take account of the detached cell population. Further, the data suggest that this phenomenon is selective to sodium arsenite, rather than to another toxic element that shares a similar mechanism of toxicity.

Keywords::

• Cleavage of pro-caspase 3
• cadmium chloride
• cell detachment
• rat hepatoma cells