Heat shock proteins increase resistance to apoptosis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Heat shock treatment enhances cell survival and resistance to apoptosis.
• The development of this resistance correlates with the synthesis of heat shock proteins (hsps).

Purpose of the Study:

• To investigate the role of heat shock proteins (hsps) 27 and 70 in cellular resistance to apoptosis.
• To determine if increased cellular levels of hsps confer protection against apoptosis-inducing agents.

Main Methods:

• U937 and Wehi-s cells were subjected to heat shock (1 hour at 42°C) to induce hsps synthesis.
• Cells were subsequently exposed to apoptosis-inducing agents (actinomycin-D, camptothecin, etoposide).
• Apoptosis was assessed via DNA fragmentation, flow cytometry, and MTT assays. Transfected cells overexpressing hsp 27 or 70 were also analyzed.

Main Results:

• Heat-shocked cells exhibited reduced apoptosis compared to control cultures when exposed to apoptosis-inducing stimuli.
• Wehi-s cells stably overexpressing hsp 27 or 70 showed increased resistance to drug-induced cell death.
• Parental cell lines displayed typical apoptosis features, including cell shrinkage and DNA breaks.

Conclusions:

• Increased cellular levels of hsp 27 or 70, achieved through heat shock or stable transfection, significantly enhance resistance to apoptosis.
• Heat shock proteins play a crucial role in protecting cells from programmed cell death.
• These findings highlight the potential of hsps as therapeutic targets for diseases involving excessive apoptosis.