Cell experiment:

Human breast cancer cell lines MCF7, MDA-MB-231, MDA-MB-361, MDA-MB-435, MDA-MB468, Hs578-T, human osteosarcoma cell line U20S, human glioblastoma cell line T98G and human cervical adenocarcinoma cell line HeLa are used. Standard XTT assays with a four-day drug treatment procedure are performed to measure the dose dependent cytotoxicity of IBR analogs in cultured cells. In brief, cells are plated on 96-well dishes one day before the drug treatment, followed by drug (e.g., IBR2) treatment on day 2 and XTT assay on day 6 after drug addition by using a commercial cell proliferation kit . Triplicate sets are measured and compiled for final data presentation[1].

IBR2 is a specific RAD51 inhibitor.

IBR2 shows interesting RAD51 inhibition activities. RAD51 is rapidly degraded in IBR2-treated cancer cells, and the homologous recombination repair is impaired, subsequently leading to cell death. The IC50 values of the original IBR2 are in the range of 12-20 µM for most tested cancer cell lines. IBR2 can inhibit the growth of triple-negative human breast cancer cell line MBA-MD-468 with an IC50 of 14.8 µM[1].

[1]. Zhu J, et al. Synthesis, molecular modeling, and biological evaluation of novel RAD51 inhibitors. Eur J Med Chem. 2015;96:196-208.