MicroRNA-138 Modulates DNA Damage Response by Repressing Histone H2AX Expression

Abstract

Precise regulation of DNA damage response is crucial for cellular survival after DNA damage, and its abrogation often results in genomic instability in cancer. Phosphorylated histone H2AX (γH2AX) forms nuclear foci at sites of DNA damage and facilitates DNA damage response and repair. MicroRNAs are short, non-protein-encoding RNA molecules, which post-transcriptionally regulate gene expression by repressing translation of and/or degrading mRNA. How microRNAs modulate DNA damage response is largely unknown. In this study, we developed a cell-based screening assay utilizing ionizing radiation-induced γH2AX foci formation in a human osteosarcoma cell line, U2OS, as the readout. By screening a library of human microRNA mimics, we identified several microRNAs that inhibited γH2AX foci formation. Among them, miR-138 directly targeted the histone H2AX 3′-UTR, reduced histone H2AX expression and induced chromosomal instability after DNA damage. Overexpression of miR-138 inhibited homologous recombination and enhanced cellular sensitivity to multiple DNA damaging agents (cisplatin, camptothecin, and ionizing radiation). Reintroduction of histone H2AX in miR-138 overexpressing cells attenuated miR-138-mediated sensitization to cisplatin and camptothecin. Our study suggests that miR-138 is an important regulator of genomic stability and a potential therapeutic agent to improve the efficacy of radiotherapy and chemotherapy with DNA damaging agents.

Hsa-let-7g miRNA regulates the anti-tumor effects of gastric cancer cells under oxidative stress through the expression of DDR genes

“…Cancer cells often display significant modification at the DDR-associated factors and develop inhibition to DNA damage-inducing agents (Tessitore et al, 2014). In the last decade, it has been documented that miRNAs were involved in the regulation of DNA damage/repair process in some cancers (Hu et al, 2010;Wang et al, 2011;Crosby et al, 2009). We have found some miRNAs possess the regulatory effects on radiosensitivity of cancer (Zhao et al, 2012).…”

“…3′-UTR of H2AX (position -19 to 1046) and Chk1 was amplifed by PCR and cloned into pGL3 (Promega) to obtain pGL3-H2AXUTR plasmid and pGL3-Chk1UTR plasmid (Lezina et al, 2013;Wang et al, 2011). The luciferase-UTR reporter plasmid that contains ATM 3′-UTR carrying a putative let-7g miRNA binding site (2210-2569) was constructed and inserted into pGL3-Luc vector named as pUTR .…”

microRNA s (9, 138, 181A, 221, and 222) and mesial temporal lobe epilepsy in developing brains

“…MiR-138 also modulates DNA damage and is an important regulator of the genomic stability [11]. Very recently, downregulation of miR-138 has been found to contribute to the constitutive activation of NF-κB [12].…”

microRNA Expression and Biogenesis in Cellular Response to Ionizing Radiation

“…Inhibition of ATM or DNA-PKcs by miR-101, miR-100, and miR-421 causes increased cellular sensitivity to IR Ng et al, 2010;Yan et al, 2010). Inhibition of H2AX expression by either miR-24 (Lal et al, 2009b) or miR-138 (Wang et al, 2011b) promotes cellular sensitivity to IR. Several other IR-responsive miRNAs, such as miR34s (Balca-Silva et al, 2012;Maki et al, 2012;Duan et al, 2013), miR-181a , miR-449a (Liu et al, 2013), let-7 (Oh et al, 2010), and miR-7 (Lee et al, 2011), can also modulate radiosensitivity by targeting the DDR, cell cycle checkpoint, or apoptosis genes.…”