CPNE3 promotes migration and invasion in non-small cell lung cancer by interacting with RACK1 via FAK signaling activation

Approximately 90% of patients diagnosed with non-small cell lung cancer (NSCLC) die due to distant metastases. However, the complicated molecular and cellular mechanisms involved in lung cancer metastasis remain poorly understood. Copine III (CPNE3), a member of a Ca(2+)-dependent phospholipid-binding protein family, was identified as a novel metastasis-associated protein in NSCLC in our previous study, however, its function in metastasis remains unclear. Here, we found that CPNE3 was expressed at high levels in NSCLC tissues and advanced TNM stages and was significantly associated with poor prognosis. In addition, CPNE3 interacted with phosphorylated erb-b2 receptor tyrosine kinase 2 (pErbB2) and receptor of activated protein C kinase 1 (RACK1) and activated the focal adhesion (FA) signaling pathway in NSCLC cells. Moreover, knockdown of RACK1 inhibited cell motility in the CPNE3-overexpressed NSCLC cells. These findings offer mechanistic insights into the oncogenic roles of CPNE3 and the pivotal effects of CPNE3 as a biomarker and therapeutic target for NSCLC metastasis.