Bloom (BLM) helicase is a DNA unwinding enzyme important for DNA repair in the homologous recombination pathway. Mutations of the BLM gene result in reduced BLM helicase activity that is associated with the rare genetic disorder, Bloom’s Syndrome, and a predisposition to developing cancer. ML-216 is the first identified small molecule inhibitor of BLM helicase (IC50 = 1.8 μM) that is 28-fold selective against the related helicases RECQ1, RECQ5, and E. coli UvrD (IC50s ≥ 50 μM). At 25-50 μM, ML-216 has been shown to dose-dependently inhibit the proliferation of BLM-expressing PSNF5 fibroblast cells but not BLM-deficient PSNG13 fibroblast cells.
