Related Articles Reciprocal paracrine interactions between normal human epithelial and mesenchymal cells protect cellular DNA from radiation-induced damage. Int J Radiat Oncol Biol Phys. 2008 Jun 1;71(2):567-77 Authors: Nakazawa Y, Saenko V, Rogounovitch T, Suzuki K, Mitsutake N, Matsuse M, Yamashita S PURPOSE: To explore whether interactions between normal epithelial and mesenchymal cells can modulate the extent of radiation-induced DNA damage in one or both types of cells. METHODS AND MATERIALS: Human primary thyrocytes (PT), diploid fibroblasts BJ, MRC-5, and WI-38, normal human mammary epithelial cells (HMEC), and endothelial human umbilical cord vein endothelial cells (HUV-EC-C), cultured either individually or in co-cultures or after conditioned medium transfer, were irradiated with 0.25 to 5 Gy of gamma-rays and assayed for the extent of DNA damage. RESULTS: The number of gamma-H2AX foci in co-cultures of PT and BJ fibroblasts was approximately 25% lower than in individual cultures at 1 Gy in both types of cells. Reciprocal conditioned medium transfer to individual cultures before irradiation resulted in approximately a 35% reduction of the number gamma-H2AX foci at 1 Gy in both types of cells, demonstrating the role of paracrine soluble factors. The DNA-protected state of cells was achieved within 15 min after conditioned medium transfer; it was reproducible and reciprocal in several lines of epithelial cells and fibroblasts, f ...
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