Title: Differential activation of signalling factors following low and high dose of gamma radiation in vivo

Authors: Anirban K. Mitra, Rakesh K. Singh, Himanshi Narang, M. Krishna, Sanjeev K. Maurya

Addresses: Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay Mumbai 400 085, India. ' Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay Mumbai 400 085, India. ' Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay Mumbai 400 085, India. ' Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay Mumbai 400 085, India. ' Department of Biotechnology, V.B.S. Purvanchal University, Jaunpur, UP, India

Abstract: The activation of signalling molecules that contribute to the development of radioresistance following radiotherapy was investigated following irradiation with very low doses (0.1 and 0.5 Gy) and high dose (1 and 3 Gy) of γ radiation. Expression of protein kinase C (PKC) was isoform specific. There was a marked difference in the response of ERK 44/42, which is known to confer radioresistance on the tumour cell. The expression at low dose was persistent till 24 hrs with a reappearance at 7 days, while the response at high dose (3 Gy) was transient, an activation at 4 hrs with a return to normal values at the subsequent time periods. These studies indicate that data obtained at high doses should not be extrapolated to low doses. The response of each signalling factor is different at different doses. Since radioadaptation and the development of radioresistance is a low dose phenomenon, ERK 44/42 seems to be the most relevant among the signalling factors.

Keywords: low dose irradiation; gamma radiation; radioresistance; radiotherapy; signalling; tumor cells; ionising radiation.

DOI: 10.1504/IJLR.2004.005435

International Journal of Low Radiation, 2004 Vol.1 No.3, pp.358 - 367

Available online: 01 Oct 2004 *

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