ABL127 is a selective and covalent inhibitor of protein methylesterase 1 (PME-1). In HEK293T and MDA-MB-231 cells, the IC50s values are 6.4 nM and 4.2 nM , respectively.

PME-1 (HEK293T):6.4 nM, PME-1 (MDA-MB-231):4.2 nM

Three described PME-1 inhibitors are tested in this assay and a thermal shift with 100 μM ABL127 is detected. Using 25 or 50 μM ABL127 also shows a shift in protein melting temperature. It is found that treatment of Ishikawa cells with ABL127 and AMZ-30 significantly decreases cell proliferation similarly to depletion of PME-1 with shRNA. It is also found that treatment of ECC-1 cells with ABL127 or AMZ-30 affects cell invasion in a dose-dependent manner. The treatment of EC cells with ABL127 leads to a significant ~45 % increase in protein phosphatase 2A (PP2A) activity, while treatment with AMZ-30 leads to a modest ~10 % increase in PP2A activity[1].

No significant decrease in tumor burden can be assessed in these pilot studies[1]. Gel-based profiles indicate that brain PME-1 is inactivated by ABL127, but overlapping serine hydrolase activities preclude a confident assessment of the extent of inactivation[2].