JG-98 is an allosteric Hsp70 inhibitor, displays high active against the breast cancer cell lines MDA-MB-231 and MCF-7 (EC50s: 0.4/0.7 μM).

JG-98 had a potency of 0.4 ± 0.03 μM against MDA-MB-231 cells and an EC50 value of 0.7 ± 0.2 μM for MCF7 cells. In MDA-MB-231 cells, the treatment of JG-98 activated apoptotic mediators (caspase-3 and PARP). Treatment of both MDA-MB-231 and MCF7 cells with JG-98 strongly affected autophagic flux [1]. JG-98 has antiproliferative activity (EC50 values between 0.3 and 4 μmol/L) across cancer cell lines from multiple origins. JG-98 destabilized FoxM1 and relieved suppression of downstream effectors, including p21 and p27 [2].

JG-98 (3 mg/kg) suppressed tumor growth in a HeLa xenograft model, though somewhat less effective [2].

Cell viability was determined using an MTT colorimetric assay with the following modifications. Briefly, cells (5 x 10^3 ) were plated into 96-well assay plates in 0.1 ml media and allowed to attach overnight. Cells were then treated with compound at various concentrations in 0.2 mL media. After the 72-hour incubation period, cells were washed in PBS (3 x 100 μL), and 10 μL MTT reagent was added with 100 μL fresh media. Cells were then incubated for 4 hr in a humidified chamber at 37 oC with 5% CO2. Insoluble formazan crystals were solubilized by addition of 0.1 mL detergent solution (4 hr at room temp., dark). Resulting colored solutions were then quantified at an absorbance of 570 nm [1].

Briefly, one million MCF7 or HeLa cells in Matrigel were subcutaneously injected bilaterally into 6 week old NCR mice. Once tumors were established, JG-98 (3 mg/kg; n=5) or vehicle control (1:1 PBS: DMSO; n=5) was introduced interperitoneally on days 2, 4 and 6. Tumor growth (10 tumors/5 mice) was measured by caliper every other day [2].