PPME1, also known as protein phosphatase methylesterase 1, is a PP2A-specific methyl esterase. It negatively regulates PP2A through demethylation at its carboxy-terminal leucine 309 residue [4]. This regulation is involved in multiple biological processes and is associated with various signaling pathways, potentially having an impact on cell growth, apoptosis, and differentiation.

In pancreatic cancer, hsa_circ_0050102 binds to miR-218-5p, which in turn regulates the expression of PPME1. Elevated PPME1 levels, promoted by hsa_circ_0050102, accelerate pancreatic cancer development [1]. In thyroid carcinoma, HOTAIR sponges miR-761, which directly targets PPME1. HOTAIR promotes cell proliferation and inhibits apoptosis by regulating PPME1 expression [2]. In pancreatic carcinoma, DNAH17-AS1 down-regulates miR-432-5p, which normally targets PPME1, thus increasing PPME1 expression and promoting tumorigenesis [3]. In gastric and lung cancer, PPME1 gene amplification is identified, and knockdown of PPME1 in amplified cell lines inhibits cell proliferation and induces apoptosis [4]. In choriocarcinoma, IMP1 promotes cell migration and invasion, potentially through regulating RSK2 and PPME1 [6]. In skeletal muscle, inhibition of Ppme1 using ABL127 or AMZ30 affects MAP kinase signaling and attenuates muscle cell differentiation [5].

In conclusion, PPME1 is a crucial regulator in multiple biological processes and disease conditions. Studies, including those using gene-knockdown models, have revealed its significance in cancer development such as in pancreatic, thyroid, gastric, lung, and choriocarcinoma, as well as in muscle cell differentiation. Understanding PPME1 provides insights into disease mechanisms and potential therapeutic targets.