pATM and γH2AX are effective radiation biomarkers in assessing the radiosensitivity of 12C6+ in human tumor cells

Abstract

BackgroundTumour radiosensitivity would be particularly useful in optimizing the radiation dose during radiotherapy. The aim of the current study was to evaluate the potential value of phosphorylated H2AX (γH2AX) and ATM (pATM) in assessing 12C6+ radiosensitivity of tumour cells.MethodsHuman cervical carcinoma HeLa cells, hepatoma HepG2 cells, and mucoepidermoid carcinoma MEC-1 cells were irradiated with different doses of 12C6+. The survival fraction was assayed with clonogenic survival method and the foci of γH2AX and pATM was visualized using immunocytochemical methods. Flow cytometry was used to assay γH2AX, pATM and the cell cycle.ResultsThe survival fraction decreased immediately in dose-dependent manner, but in turn, significantly increased during 24 h after 12C6+ irradiation. Both γH2AX and pATM foci accumulated linearly with doses and with a maximum induction at 0.5 h for γH2AX and 0.5 or 4 h for pATM, respectively, and a fraction foci kept for 24 h. The expression of γH2AX and pATM was in relation to cell cycle. The G0/G1 phase cells had the highest expression of γH2AX after 0.5 h irradiation and then decreased to a lower level at 24 h after irradiation. An obvious increase of pATM in G2/M phase was shown after 24 h of 2 and 4 Gy irradiation. The significant G2/M phase arrest was shown. There was a close relationship between the clonogenic survival and γH2AX and pATM expression both in timing and dose in response to 12C6+.ConclusionsThe rate of γH2AX and pATM formation and loss may be an important factor in the response of cells to 12C6+. pATM and γH2AX are effective radiation biomarkers in assessing the radiosensitivity of 12C6+ in human tumor cells.

Acquired resistance to tyrosine kinase inhibitors may be linked with the decreased sensitivity to X-ray irradiation

“…The number of the residual foci of the DSB-binding proteins, such as the phosphorylated histone H2AX (γH2AX), is known to correlate with the cell survival after IR and is used as the marker of radioresistance in cell populations [ 35 – 38 ]. Recently, more accurate assays have been developed that use quantization of both H2AX foci and foci of serine 1981-phosphorylated active ATM (Ataxia Telangiectasia Mutation) kinase (pATM) [ 39 ]. This kinase may be activated activated in response to DSB and, in turn, phosphorylates histone H2AX [ 40 ].…”

Residual γH2AX foci induced by low dose x-ray radiation in bone marrow mesenchymal stem cells do not cause accelerated senescence in the progeny of irradiated cells

“…АТМ protein (ataxia-telangiectasia mutated) is the major kinase that phosphorylates histone Н2AX in response to the IR-induced DNA DSB formation [ 40 ], and the slow phase of the IR-induced DSB repair is believed to be ATM-mediated [ 39 ]. We next performed a comparative analysis of γH2AX and phosphorylated ATM (pATM) localization in response to either low or intermediate dose of X-rays (Fig.…”

Harnessing the targeting potential of differential radiobiological effects of photon versus particle radiation for cancer treatment

“…Remarkably, protons are usually low‐LET radiation, and their biological effects are approximately identical to photons (the RBE is 1.1; Saager et al, 2018), whereas the biological effects of carbon ions are more pronounced than protons (the RBE is ∼2.3; Si et al, 2019). Unlike low‐LET IR, which produces sparse ionising events randomly distributed throughout the cell to eventually induce less complex DNA damage (Lorat, Timm, Jakob, Taucher‐Scholz, & Rübe, 2016), high‐LET IR predominantly deposits a high energy density at the end of the range (the Bragg Peak), causing more extensive damage, and often, fateful biological consequences (Liu et al, 2018; Zhao et al, 2017). High‐LET radiation contributes to clustered DNA damage, a DNA lesion complex that includes two or more individual lesions within a few helical DNA turns, which is largely responsible for the deleterious effects of high energy IR (Park, Peoples, Madugundu, Sanche, & Wagner, 2013; Q. Zhang et al, 2016).…”