Effects of Gamma-rays, Proton and Alfa Particles Irradiation on Ionic Currents in Human Glioblastoma Multiform Cell Line

Many types of ionizing radiation (IR), such as X-rays, gamma rays and charged particles, can be used to locally control a wide range of tumors. In order to assess efficient radiotherapy and avoid side effects such as radiation-induced second cancer or normal cells death, an increasing number of studies are focused on doses, energy and source of radiation [1,2]. Biological tissues operate through cell membrane to coordinate cell functions against constant exposure to an array of potentially toxic agents, exogenously from the environment and endogenously from signaling and metabolism. It is well known that cell membranes are a significant target of IR by affecting membrane structures and leading to expression of intracellular damages [3]. The transduction pathway by which IR affects cells functionality remains still unclear. Mammalian non-excitable cells express a wide range of potassium (K+) channels, such as voltage–dependent (Kv), large-conductance Ca2+-dependent (BKCa) and ATP-dependet (KATP). These channels are specifically involved in many physiological functions such as volume regulation and mobility (implicated in cell division, migration and invasiveness), hormonal secretion, cell proliferation and apoptosis [4-6]. A malfunction of these processes is a hallmark of neoplastic progression and tumorigenic phenotype establishment [7]. In the present work we evaluated the effects of three types of IR (gamma rays, protons and helium-4 ions) at different doses (from 0.25 to 2 Gy) on whole-cell K+ currents (IK) recorded from a human glioblastoma multiform cell line (T98G).