Hyperthermia enhances CD95-ligand gene expression in T lymphocytes

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• Hyperthermia is a potential cancer treatment that modulates immune responses.
• The Fas/Fas ligand (FasL) system is crucial for T cell-mediated apoptosis and immune regulation.
• Understanding hyperthermia's impact on FasL in T cells is key for its therapeutic application.

Purpose of the Study:

• To investigate the effect of hyperthermia on the activation of the fas-L gene in T lymphocytes.
• To elucidate the molecular mechanisms underlying hyperthermia-induced FasL expression and cytotoxicity.

Main Methods:

• Assessed hyperthermia's impact on FasL-mediated cytotoxicity and fas-L mRNA expression in activated T cell lines.
• Analyzed the activity of transcription factors AP-1, NF-kappaB, and heat shock factor-1 (HSF-1) on the fas-L promoter.
• Utilized dominant-negative mutants of HSF-1 and protein kinase C (PKC) isoforms (PKCepsilon, PKCtheta) to probe regulatory pathways.

Main Results:

• Hyperthermia significantly enhanced FasL-mediated cytotoxicity, fas-L mRNA expression, and promoter activity in activated T cells.
• Heat treatment increased transcriptional activity of AP-1 and NF-kappaB, correlating with their expression and nuclear translocation.
• HSF-1 was identified as a transactivator of the fas-L promoter, and PKCepsilon/PKCtheta activity was critical for hyperthermia's enhancing effect.

Conclusions:

• Hyperthermia upregulates fas-L gene expression and enhances T cell-mediated cytotoxicity through AP-1, NF-kappaB, and HSF-1 pathways.
• Modulation of PKC activity plays a significant role in hyperthermia's immunomodulatory effects on T cells.
• These findings support hyperthermia's potential as an adjuvant therapy for cancer by enhancing anti-tumor immune responses.