Pyrimidine tract-binding protein 1 mediates pyruvate kinase M2-dependent phosphorylation of signal transducer and activator of transcription 3 and oncogenesis in anaplastic large cell lymphoma

Abstract

PKM2 (pyruvate kinase M2), a critical regulator of glycolysis, is phosphorylated by numerous growth factor receptors and oncogenic tyrosine kinases including NPM-ALK which is expressed in a subset of aggressive T-cell non-Hodgkin lymphomas known as anaplastic large cell lymphoma, ALK-positive. Our previous work demonstrated that phosphorylation of Y105-PKM2 by NPM-ALK regulates a major metabolic shift to promote lymphomagenesis. In addition to its role in metabolism, recent studies have shown that PKM2 promotes oncogenesis by phosphorylating nuclear STAT3 (signal transducer and activator of transcription 3) and regulating transcription of genes involved in cell survival and proliferation. We hypothesized that identification of novel PKM2 interactors could provide additional insights into its expanding functional role in cancer. To this end, immunocomplexes of FLAG-tagged PKM2 were isolated from NPM-ALK-positive ALCL (anaplastic large cell lymphoma) cells and subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS) which led to the identification of polypyrimidine tract-binding protein (PTBP1) as a novel interactor of PKM2. The interaction between PTBP1 and PKM2 was restricted to the nucleus and was dependent on NPM-ALK mediated Y105 phosphorylation of PKM2. Stable shRNA-mediated silencing of PTBP1 resulted in a marked decrease in pY105-PKM2 and pY705-STAT3 which led to decreased ALCL cell proliferation and colony formation. Overall, our data demonstrate that PTBP1 interacts with PKM2 and promotes ALCL oncogenesis by facilitating PKM2-dependent activation of STAT3 within the nucleus.

Protein kinase function of pyruvate kinase M2 and cancer

“…Nuclear PKM2 has been demonstrated to phosphorylate STAT3 at Tyr705 using a phosphate group from PEP, subsequently activating transcription of MEK5 [ 20 , 73 ] and HIF-1α [ 15 ]. The interaction of polypyrimidine tract-binding protein (PTBP1) and PKM2 facilitates phosphorylation of STAT3 Tyr705 and promotes oncogenesis in lymphoma [ 74 ]. PKM2-mediated STAT3 phosphorylation promotes progression of esophagus cancer via TGF-β1-mediated EMT [ 75 ].…”

18F-FDG PET/CT imaging findings in anaplastic large cell lymphoma, a rare subtype of lymphoma

“…The intensity of 18 F-FDG uptake in ALCL tumours may not be an indicator of treatment response and prognosis because ALK-positive ALCL was always reported to have a better prognosis than ALK-negative ALCL [1,[5][6][7]30]. Experimental results reported by McDonnell SR may explain why ALK-positive ALCL had a higher 18 F-FDG uptake [31]. Their study demonstrated that NPM-ALK induced a metabolic shift towards aerobic glycolysis.…”

Roles of PTBP1 in alternative splicing, glycolysis, and oncogensis

“…3.2.1 Glycolysis PTBP1 acts as an alternative splicing repressor of the PKM1, leading to the expression of the PKM2 (Shinohara et al, 2016). PTBP1 increases the transformation of PKM1 to PKM2, and the upregulation of PTBP1 is associated with the proliferation, invasion, and migration of human breast cancer, clear-cell renal cell carcinoma (ccRCC), and anaplastic large cell lymphoma (ALCL) (He et al, 2014;Hwang et al, 2017;Jiang et al, 2017). The modulation of PKM alternative splicing and the upregulation of PTBP1 in pancreatic ductal adenocarcinoma (PDAC) cells confers drug resistance, which leads to the transition to drug-resistant PDAC (DR-PDAC) (Calabretta et al, 2016).…”

“…PKM2 functions as an essential gene for the Warburg effect, a cancer-specific energy metabolism state that is regulated by the alternative splicing of PTBP1 (Hwang et al, 2017;Taniguchi et al, 2018). PTBP1 is a splicer of PKM mRNA and a positive regulator of the Warburg effect.…”