Hypoxia-induced changes in radiation sensitivity in human melanoma cells: importance of oxygen-regulated proteins, adenylate energy charge and cell cycle distribution.

Abstract

BACKGROUND AND PURPOSE:

The effects of transient hypoxia on the radiation sensitivity of human tumour cells have so far been investigated only to a limited extent, and only up to 12 h after reoxygenation. We irradiated cells shortly after reoxygenation (<1 h) or at prolonged times after reoxygenation (24 h and 48 h) in order to examine possible relationships between changes in radiation sensitivity on the one hand and changes in rates of synthesis of oxygen-regulated proteins, changes in energy metabolism and changes in cell cycle distribution on the other.

MATERIALS AND METHODS:

Four human melanoma cell lines (A-07, D-12, R-18 and U-25) were included in the study. After hypoxia treatment (4 h or 16 h) and reoxygenation, cells were either irradiated as monolayers at a dose rate of 2.0 cGy/min or prepared for protein analysis, energy charge measurements or flow cytometric measurements of DNA.

RESULTS:

U-25 was the only line that showed increased radiation sensitivity shortly after reoxygenation, possibly because of extensive energy depletion. A-07 was the only line that showed increased radiation sensitivity at prolonged times after reoxygenation, possibly because of hypoxia-induced changes in the cell cycle distribution. The rates of synthesis of oxygen-regulated proteins (GRP78, GRP94, HSP70 and HSP90) were transiently perturbed to a similar extent in all lines after hypoxia treatment.

CONCLUSION:

The radiation sensitivity of the human melanoma cell lines was changed only to a minor extent by transient exposure to hypoxia.

• Authors: T Danielsen, R Skøyum, E K Rofstad
• Journal: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology (Radiother Oncol) Vol. 44 Issue 2 Pg. 177-82 (Aug 1997) ISSN: 0167-8140 [Print] Ireland
• PMID: 9288847 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carrier Proteins
• Endoplasmic Reticulum Chaperone BiP
• HSP70 Heat-Shock Proteins
• HSPA5 protein, human
• Heat-Shock Proteins
• Membrane Proteins
• Molecular Chaperones
• glucose-regulated proteins

Topics

• Carrier Proteins (biosynthesis)
• Cell Cycle
• Cell Hypoxia
• Endoplasmic Reticulum Chaperone BiP
• Energy Metabolism
• HSP70 Heat-Shock Proteins (biosynthesis)
• Heat-Shock Proteins
• Humans
• Melanoma (metabolism, pathology, radiotherapy)
• Membrane Proteins (biosynthesis)
• Molecular Chaperones (biosynthesis)
• Radiation Tolerance
• Tumor Cells, Cultured