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Increased gap junctional intercellular communication in Syrian hamster embryo cells treated with oxidative agents
1Laboratory for Environmental and Occupational Cancer, Norwegian Radium Hospital, Oslo.
Carcinogenesis
|February 1, 1994
Summary
Oxidative agents, including hydrogen peroxide (H2O2), significantly increase gap junctional intercellular communication (GJIC) in cells. This enhancement is reversible and does not involve the cAMP/protein kinase A pathway, suggesting novel signaling mechanisms for GJIC regulation.
Area of Science:
- Cell Biology
- Molecular Signaling
- Toxicology
Background:
- Gap junctional intercellular communication (GJIC) is crucial for cell-to-cell signaling.
- The 12-O-tetradecanoylphorbol-13-acetate (TPA)-sensitive Syrian hamster embryo (SHE) cell line BPNi is a model for studying GJIC.
- The cAMP/protein kinase A (PKA) system is a known regulator of GJIC.
Purpose of the Study:
- To investigate the effects of various oxidative agents and UV light on GJIC in BPNi cells.
- To elucidate the signaling pathways involved in the modulation of GJIC by hydrogen peroxide (H2O2).
Main Methods:
- Exposure of BPNi cells to K2CrO4, H2O2, benzoyl peroxide, menadione, KBrO3, and UV365nm.
- Measurement of GJIC levels using established assays.
- Investigation of the role of hydroxyl radicals, catalase, and the cAMP/PKA pathway using specific inhibitors and scavengers.
Main Results:
- All tested agents increased GJIC by 50-100%.
- H2O2 reversed TPA-induced decreases in GJIC and its enhancement was partially dependent on hydroxyl radicals and catalase.
- H2O2 did not significantly alter cAMP levels, and its GJIC enhancement was less sensitive to PKA inhibitors compared to forskolin.
Conclusions:
- Oxidative agents effectively enhance GJIC in SHE cells.
- The mechanism of H2O2-induced GJIC enhancement appears to be independent of the cAMP/PKA signaling pathway.
- Novel signaling pathways may regulate GJIC in response to oxidative stress.