CIP2A Regulates Cell Proliferation Via the AKT Signaling Pathway in Human Lung Cancer

Cancerous inhibitor of PP2A (CIP2A) is an intracellular endogenous protein phosphatase 2A (PP2A) inhibitor with oncogenic activities. Initially identified as a tumor-associated antigen (TAA) in gastric and liver cancer patients, CIP2A was overexpressed in a variety of cancer types. The overexpression of CIP2A in cancer cells is associated with increased cell proliferation. However, the mechanism of CIP2A in cancer cell proliferation remains poorly understood. In the present study, we reported that CIP2A can regulate AKT phosphorylation at S473 under growth factor stimulation and our results also showed that CIP2A may promote cell proliferation through the AKT signaling pathway. Notably, depletion of CIP2A did not induce a global change of AKT phosphatase activity, which indicated that CIP2A may recognize specific AKT targets and play certain roles in the signaling pathway. In addition, we detected that CIP2A expression was associated with mTOR phosphorylation. Our further analysis corroborated the relationship between CIP2A and AKT-mTOR signaling pathway. Therefore, our study addressed a novel role of CIP2A in mediating cancer progression through interacting with the AKT-mTOR signaling pathway.