Systematic Screen Identifies miRNAs That Target RAD51 and RAD51D to Enhance Chemosensitivity

Abstract

Homologous recombination (HR) mediates error-free repair of DNA double-strand breaks (DSBs). RAD51 is an essential protein for catalyzing HR and its recruitment to DSBs is mediated by many factors including RAD51, its paralogs, and breast/ovarian cancer susceptibility gene products BRCA1/2. Deregulation of these factors leads to impaired DNA repair, genomic instability, and cellular sensitivity to chemotherapeutics like cisplatin and poly (ADP-ribose) polymerase (PARP) inhibitors. microRNAs (miRs) are short, non-coding RNAs that post-transcriptionally regulate gene expression; however, the contribution of miRs in the regulation of HR is not well understood. To address this, a library of human miR mimics was systematically screened to pinpoint several miRs that significantly reduce RAD51 foci formation in response to ionizing radiation (IR) in human osteosarcoma cells. Subsequent study focused on two of the strongest candidates, miR-103 and miR-107, as they are frequently deregulated in cancer. Consistent with the inhibition of RAD51 foci formation, miR-103 and miR-107 reduced homology-directed repair and sensitized cells to various DNA damaging agents, including cisplatin and a PARP inhibitor. Mechanistic analyses revealed that both miR-103 and miR-107 directly target and regulate RAD51 and RAD51D, which is critical for miR-103/107-mediated chemosensitization. Furthermore, endogenous regulation of RAD51D by miR-103/107 was observed in several tumor subtypes. Combined, these data show that miR-103 and miR-107 overexpression promotes genomic instability and may be used therapeutically to chemosensitize tumors. Implications These findings demonstrate a role for miR-103 and -107 in regulating DNA damage repair, thereby identifying new players in the progression of cancer and response to chemotherapy.

DNA damage responsive miR-33b-3p promoted lung cancer cells survival and cisplatin resistance by targeting p21WAF1/CIP1

“…26 miR-103 and miR-107 directly targeted RAD51, which was an essential protein for catalyzing HR repair of DNA double-strand breaks (DSBs). 27 Additionally, another critical component of non-homologous end joining (NHEJ) for DSBs repair-Ku80, was a direct target of miR-526b. Our data unraveled that A549 cells with miR-33b-3p overexpression exhibited lower levels of gH2A.X under cisplatin treatment, indicating that miR-33b-3p promoted DNA damage repair.…”

Quinazolinone derivatives as inhibitors of homologous recombinase RAD51

“…Depending on the availability of the building blocks, the cinnamide analogues (B) were also constructed by Heck coupling of the corresponding aromatic bromide with acrylamide C. After introducing motif 1 as an amine through amide coupling (D to E), the intermediates were cyclized under mild dehydration conditions with iodine and hexamethyldisilazine 18 to give the desired quinazolinone products (F). In this way, one series of compounds incorporated alkyl and cycloalkyl substituents (1)(2)(3)(4)(5)(6)(7)(8), and another series contained substituted aromatics with a variable spacer -(CH 2 )n-(n =0-2, 9-27). The latter series was designed to optimally target residues F195 and Y191 through piinteractions.…”

“…RAD51 has been recognized as a potential oncotarget due to its critical role in HR, and contributes to an aggressive cellular phenotype and resistance to therapeutics. Several small molecule RAD51 inhibitors have been discovered by high-throughput screening of compound libraries, notably B02 [5][6][7] , the RI series [8][9][10] and the IBR2 series 11,12 ( Figure 1). Alternatively, a fragmentbased screening approach at Cambridge identified another series of compounds 13,14 ( Figure 1).…”

Ovarian Cancer: Interplay of Vitamin D Signaling and miRNA Action

“…It has recently been shown that miR-22, miR-93, miR-106b, miR-451 were aberrantly expressed in the serum of ovarian cancer patients (Ji et al, 2014). There is rapidly accumulating evidence suggesting that miR-103 and miR-107 restore sensitivity of resistant ovarian cancer cells to chemotherapeutic drugs via targeting of RAD51 and RAD51D Huang et al (2013). It has previously been shown that enhancer of zeste 2 (EZH2) promoted cellular proliferation and enhanced invasive potential of epithelial ovarian cancer cells (Li et al, 2010).…”