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Updated: Jun 1, 2026
RNA Interference-based Investigation of the Function of Heat Shock Protein 27 during Corneal Epithelial Wound Healing
Published on: September 27, 2016
Coinduction of hsp27 phosphorylation and drug-resistance in chinese-hamster cells
Abstract:
Treatments of Chinese hamster fibroblasts with A23187, 2-deoxyglucose, tunicamycin, beta-mercaptoethanol or glucosamine induce an increase in cell resistance to doxorubicin and VM-26 that attains a maximum after 8 h of treatment. We tested the possibility that HSP27, a heat shock protein whose overexpression in cells was shown to confer thermoresistance and chemoresistance, might also be associated with this acquisition of drug resistance. [H-3]leucine incorporation and immunoblot analyses showed that the increased resistance was not accompanied by the synthesis or accumulation of HSP27 or other heat shock proteins. However, drug resistance promoting agents all stimulated protein kinase activities that phosphorylated HSP27 in vitro and stimulated incorporation of P-32 into HSP27 in vivo. HSP27 is thought to exert in unstressed cells functions linked with growth signal pathways. It is suggested that stimulation of HSP27 phosphorylation may modulate a protective function associated with the maintenance of signal transduction homeostasis.
Insights
Certain chemical treatments enhance Chinese hamster fibroblast resistance to chemotherapy drugs like doxorubicin. This drug resistance is linked to the phosphorylation of heat shock protein 27 (HSP27), not its increased synthesis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Heat shock proteins (HSPs), such as HSP27, are known to confer resistance to various cellular stresses, including thermoresistance and chemoresistance.
- Previous studies indicated that overexpression of HSP27 can lead to increased chemoresistance in cells.
Purpose of the Study:
- To investigate the potential role of HSP27 in acquired chemoresistance induced by specific chemical treatments in Chinese hamster fibroblasts.
- To determine if the increased drug resistance observed is associated with the synthesis or accumulation of HSP27 or other heat shock proteins.
Main Methods:
- Chinese hamster fibroblasts were treated with agents like A23187, 2-deoxyglucose, tunicamycin, beta-mercaptoethanol, and glucosamine.
- Cellular resistance to doxorubicin and VM-26 was assessed after 8 hours of treatment.
- [H-3]leucine incorporation and immunoblot analyses were performed to detect protein synthesis and accumulation.
- Protein kinase activity and in vivo/in vitro phosphorylation of HSP27 using P-32 were measured.
Main Results:
- Treatments with the specified agents increased fibroblast resistance to doxorubicin and VM-26.
- This acquired drug resistance was not correlated with increased synthesis or accumulation of HSP27 or other heat shock proteins.
- The drug resistance-inducing agents stimulated protein kinase activities that phosphorylated HSP27 both in vitro and in vivo.
Conclusions:
- The acquisition of chemoresistance in Chinese hamster fibroblasts is not mediated by HSP27 synthesis or accumulation.
- Stimulation of HSP27 phosphorylation by these agents suggests a role for post-translational modification in drug resistance.
- HSP27 phosphorylation may modulate protective functions related to signal transduction homeostasis, potentially influencing cell survival pathways.
