Profilin 2 regulates pyruvate kinase M2 nuclear translocation and potentiates tumor angiogenesis in non-small cell lung cancer

Abstract

Abstract Profilin 2 (PFN2) is an actin-binding protein important for cancer initiation and progression. However, the function and precise role of PFN2 in non-small cell lung cancer (NSCLC) remain unclear. Here, we assessed the expression levels of PFN2 in tissue from patients with NSCLC; identified binding partners using mass spectrometry, co-immunoprecipitations, and molecular modeling; and studied the angiogenic-promoting function of PFN2 using 3D droplet cultures and tube-formation assays. We found that upregulated PFN2 expression is associated with poor prognosis in patients with NSCLC. Knockdown of PFN2 significantly impaired the proliferation and angiogenesis of NSCLC cells, both in vivo and in vitro. Mechanistically, PFN2 physically interacts with pyruvate kinase M2 (PKM2) and modulates extracellular-signal regulated kinase 1/2 (ERK1/2)-mediated phosphorylation of PKM2 at S37, which substantially increases its nuclear translocation. PFN2 knockdown lead to reduced expression of PKM2, p65-NF-κB, and hypoxia-inducible factor (HIF)-1α and inhibited the nuclear translocation of PKM2. This resulted in impaired formation of the PKM2-HIF-1α-p65-NF-κB transcription complex, leading to decreased expression of its downstream target genes VEGFA, CCND1, and MAP2K5. Moreover, mutations in PFN2 at Y134 or S138 impaired its binding to PKM2, nuclear translocation of PKM2, and functionally inhibited angiogenesis in lung cancer cells. Overall, our data provide insights into the role of PFN2 in the regulation of lung cancer angiogenesis and indicate that PFN2 may serve as a therapeutic target against NSCLC.