Pyruvate kinase M2 promotes pancreatic ductal adenocarcinoma invasion and metastasis through phosphorylation and stabilization of PAK2 protein

Abstract

Pyruvate kinase muscle isozymes (PKMs) have crucial roles in regulating metabolic changes during carcinogenesis. A switch from PKM1 to PKM2 isoform was thought to lead to aerobic glycolysis promoting carcinogenesis, and was considered as one of the cancer signatures. However, recent evidence has argued against the existence of PKM isoform switch and related metabolic effects during cancer progression. We compared the effects of PKM1 and PKM2 in cell invasiveness and metastasis of pancreatic ductal adenocarcinoma (PDAC). Both PKM1 and PKM2 expression affected cell migration and invasion abilities of PDAC cells, but only knockdown of PKM2 suppressed metastasis in a xenograft model. By comparing the established PKM2 mutants in the regulation of cell invasion, we found that PKM2 may control cell mobility through its protein kinase and phopho-peptide binding abilities. Further survey for PKM2-associated proteins identified PAK2 as a possible phosphorylation target in PDAC. In vitro binding and kinase assays revealed that PKM2 directly phosphorylated PAK2 at Ser20, Ser141, and Ser192/197. Knockdown of PKM2 decreased PAK2 protein half-life by increasing ubiquitin-dependent proteasomal degradation. Moreover, we identified PAK2 as an HSP90 client protein and the mutation at Ser192/197 of PAK2 reduced PAK2-HSP90 association. Knockdown of PAK2 diminished in vitro cell mobility and in vivo metastatic ability of PKM2 overexpressed PDAC cells. PKM2 and PAK2 protein expression also positively correlated with each other in PDAC tissues. Our findings indicate that PKM2-PAK2 regulation is critical for developing metastasis in PDAC, and suggest that targeting the PKM2/HSP90/PAK2 complex has a potential therapeutic value in this deadly disease.

Identification of novel genes associated with a poor prognosis in pancreatic ductal adenocarcinoma via a bioinformatics analysis

“…Pyruvate kinase muscle isozymes (PKMs) play an important role in adjusting metabolic changes during carcinogenesis. Cheng et al (2018) [59] revealed that the increased expression of PKM1 and PKM2 affected cell invasion and migration in PDAC cells. Lu et al (2018) [60] analyzed the related microarray datasets (GSE15471, GSE62452, GSE102238, GSE62165, and GSE16515) and identified the top 21 genes with high connectivity degrees; among them, PLAU is a plasminogen activator, ITGA3 plays a vital function in EMT, and the high expression of PLAU and ITGA3 is related to poor survival, consistent with the current research.…”

Pyruvate kinase M2 regulates homologous recombination-mediated DNA double-strand break repair

“… 31 PKM2 has also been reported to phosphorylate STAT3 at Y705, thereby enhancing its transcriptional activity. 16 More recently, PKM2 has been found to phosphorylate H2AX, 32 PAK2, 33 and SNAP-23. 34 While the ability of PKM2 to directly phosphorylate proteins has been challenged, 35 unbiased proteomic screens have identified over 900 substrates for PKM2.…”

Cutting off the fuel supply to calcium pumps in pancreatic cancer cells: role of pyruvate kinase-M2 (PKM2)

“…Pyruvate kinase-M2 (PKM2) is a major oncogenic ATPgenerating glycolytic enzyme and is particularly overexpressed in pancreatic cancer. [12][13][14][15][16][17] PKM2 has a low catalytic activity, producing a bottleneck at the terminal end of glycolysis. 12,18 This is advantageous to cancer cells as it results in the buildup of glycolytic intermediates, which are then utilised in nucleotide and lipid biosynthesis to aid rapid proliferation.…”