Is there a relationship between hypoxia, contact resistance, and intercellular communication?

Area of Science:

• Radiobiology
• Cellular communication
• Tumor microenvironment

Background:

• Radiation survival curves are crucial for understanding cell response to ionizing radiation.
• Multicell spheroids mimic solid tumor structures, offering a model to study cellular interactions.
• Hypoxic cells within tumors often exhibit radioresistance, complicating radiation therapy.

Purpose of the Study:

• To investigate the influence of intercellular communication on radiation survival curves in multicellular spheroids.
• To determine the role of hypoxia and the 'contact effect' in spheroid radiobiology.
• To explore the potential implications for solid tumor radiation response.

Main Methods:

• Culturing of multicellular spheroids from cells with and without gap-junction communication.
• Analysis of radiation survival curves for both communicating and non-communicating spheroids.
• Comparison of spheroid survival data with corresponding monolayer cultures.

Main Results:

• Communicating spheroids exhibited survival curves lacking a radioresistant hypoxic fraction.
• A uniform increase in radioresistance, attributed to the 'contact effect', was observed in communicating spheroids compared to monolayers.
• Non-communicating spheroids displayed biphasic survival curves, indicating the presence of hypoxic cells and the absence of a contact effect.

Conclusions:

• Intercellular communication via gap junctions significantly alters radiation survival curves by mitigating the radioresistance of hypoxic cells.
• The 'contact effect' enhances overall radioresistance in communicating spheroids.
• Findings suggest that intercellular communication and its impact on hypoxia may be relevant to the radiation response of solid tumors.