Endogenous Retrovirus Activation as a Key Mechanism of Anti-Tumor Immune Response in Radiotherapy.

Endogenous Retrovirus Activation as a Key Mechanism of Anti-Tumor Immune Response in Radiotherapy. Radiat Res. 2020 Feb 19;: Authors: Lee AK, Pan D, Bao X, Hu M, Li F, Li CY Abstract The generation of DNA double-strand breaks has historically been taught as the mechanism through which radiotherapy kills cancer cells. Recently, radiation-induced cytosolic DNA release and activation of the cGAS/STING pathway, with ensuing induction of interferon secretion and immune activation, have been recognized as important mechanisms for radiation-mediated anti-tumor efficacy. Here we demonstrate that radiation-induced activation of endogenous retroviruses (ERVs) also plays a major role in regulating the anti-tumor immune response during irradiation. Radiation-induced ERV-associated dsRNA transcription and subsequent activation of the innate antiviral MDA5/MAVS/TBK1 pathway led to downstream transcription of interferon-stimulated genes. Additionally, genetic knockout of KAP1, a chromatin modulator responsible for suppressing ERV transcription sites within the genome, enhanced the effect of radiation-induced anti-tumor response in vivo in two different tumor models. This anti-tumor response was immune-mediated and required an intact host immune system. Our findings indicate that radiation-induced ERV-dsRNA expression and subsequent immune response play critical roles in clinical radiotherapy, and manipulation of epigenetic regulators and the dsRNA-...
Source: Radiation Research - Category: Physics Authors: Tags: Radiat Res Source Type: research