Tag Archives: ionizing radiation

The effect of ionizing radiation with low dose rate on the state of electron transfer chain of enterocyte mitochondria of rat small intestine

L. V. Grubska1, V. M. Voitsitskiy2, S. V. Khyzhnayk3

1Іnstitute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kyiv;
2National University of Life and Environmental Sciences of Ukraine, Kyiv;
3Taras Shevchenko Kyiv National University, Ukraine;
е-mail: hsv@univ.kiev.ua

The influence of ionizing radiation with low absorbed dose rate (55 mGy·min-1) in 1, 12 and 24 hours after irradiation in doses of 0.1; 0.5 and 1.0 Gy on functional state of the electron transfer  chain of the rat small intestine mitochondria was investigated by assessment of the oxygen consumption rate. The uncoupling of oxidation and phosphorylation, a decrease of phosphorylation rate and inhibition of ATP hydrolysis reactions were established in mitochondria in dependence on the irradiation dose and time interval after irradiation. The functional peculiarities of the oxidation-phosphorylation coupling sites of the mitochondrial electron transfer chain were detected.

Biochemical effects of combined action of γ-irradiation and paclitaxel on anaplastic thyroid cancer cells

V. M. Pushkarev, O. I. Kovzun, V. V. Pushkarev, M. D. Tronko

State Institution V. P. Komisarenko Institute of Endocrinology and Metabolism,
National Academy of Medical Sciences of Ukraine, Kyiv;
e-mail: pushkarev.vm@gmail.com

The aim of the paper was to describe the biochemical effects of Paclitaxel (Ptx), γ-irradiation (IR) and their combination in undifferentiated thyroid cancer cells (ATC). IR activated common DNA damage-induced signaling and manifested certain mitogenic effect by inactivation of retinoblastoma protein (pRb). There was clear antagonism between Ptx and IR relative to cell cycle regulators – tumor suppressor p53, pRb, CHK2 and c-Abl as well as proapoptotic Bax expression, but combined action of both agents enhanced caspase-3 and, especially, caspase-8 activation. The Ptx at low (1-25 nM) concentrations caused noticeable radioprotective effect.
Thus, in ATC cells the ionizing radiation and Ptx exhibited competitive effects upon phosphorylation of cell cycle controllers: p53, pRb, CHK2, cAbl and expression of Вах. At the same time, the combined effect of radiation and Ptx enhanced antiapoptotic Bcl-2 phosphorylation, caspases activation and survivin expression. The net effect of these events during the first 48-72 h of cells incubation can be considered as antiapoptotic – Ptx attenuated cytotoxic effect of IR.