Design, synthesis and interaction of BRC4 analogous peptides with RAD51(241–260)

Design, synthesis and properties of peptide inhibitors based on BRCA1856-871

Overexpression of RAD51 protein was found to increase drug resistance in breast cancer cells. Breast cancer susceptibility gene 1 (BRCA1) protein can specifically bind to RAD51 protein and regulate the expression level of RAD51 protein. Based on previous studies, eight modified peptides were obtained by modifying the N-terminus of the key peptide segment 856-871 of BRCA1 with nicotinic acid (NA) and its derivatives. The interaction of BRCA1^856-871 and modified peptides with the RAD51^158-180 target peptide was investigated by fluorescence and circular dichroism spectroscopies. The results showed that the binding ability of 2-TFM-NA-PP to RAD51^158-180 was significantly enhanced. BRCA1^856-871 and modified peptides were studied by in vitro cell experiments. The results showed that the antitumor activity of 5-TFM-NA-PP was significantly enhanced compared with BRCA1^856-871.

Understanding the DNA double-strand break repair and its therapeutic implications

Repair of DNA double-strand breaks (DSBs) and its regulation are tightly integrated inside cells. Homologous recombination, nonhomologous end joining and microhomology mediated end joining are three major DSB repair pathways in mammalian cells. Targeting proteins associated with these repair pathways using small molecule inhibitors can prove effective in tumors, especially those with deregulated repair. Sensitization of cancer to current age therapy including radio and chemotherapy, using small molecule inhibitors is promising and warrant further development. Although several are under clinical trial, till date no repair inhibitor is approved for commercial use in cancer patients, with the exception of PARP inhibitors targeting single-strand break repair. Based on molecular profiling of repair proteins, better prognostic and therapeutic output can be achieved in patients. In the present review, we highlight the different mechanisms of DSB repair, chromatin dynamics to provide repair accessibility and modulation of inhibitors in association with molecular profiling and current gold standard treatment modalities for cancer.