Lim, K.-H. | Search bioRxiv

bioRxiv2025

Targeting Tumor-intrinsic TAK1 triggers anti-tumor immunity and sensitizes pancreatic cancer to checkpoint blockade

Background and AimsTargeting the Transforming Growth Factor-{beta} (TGF-{beta}) pathway to reverse the immunologically "cold" tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) remains clinically unsuccessful, warranting novel therapeutic strategies. MethodsWe developed a novel tumor-CD8 T cell co-culture to interrogate the TGF-{beta} signaling pathways that promotes T cell-mediated cytotoxicity. We performed multiplex immunohistochemistry (mIHC) on human PDAC samples to correlate cell-type specific TGF-{beta} pathway activation and CD8 T cell abundance. We employed specific pathway inhibitor and newly generated genetically-engineered mouse models (GEMMs) and confirmed our findings using single-cell RNA sequencing, flow cytometry and mIHC. We performed proteomics and various in vitro assays to establish the molecular mechanisms. ResultsWe identify TGF-{beta}-activated kinase 1 (TAK1 or MAP3K7) as an aberrantly activated kinase in human and mouse PDAC tissues that is associated with T cell dysfunction. Pharmacological inhibition of TAK1 with Takinib, or genetic deletion of MAP3K7 in autochthonous p48-Cre;TP53flox/flox;LSL-KRASG12DGEMM, enhances intratumoral CD4+ and CD8+ effector T cell infiltration and renders immune checkpoint blockade (ICB) effective. Mechanistically, TAK1 inhibition induces DNA damage and cytoplasmic DNA leakage, which activates the cyclic GMP-AMP synthase-Stimulator of Interferon Genes (cGAS-STING) DNA sensing pathway, triggering inflammatory responses that promote adaptive immune cell infiltration. At the molecular level, TAK1 phosphorylates Ephrin Receptor A2 (EphA2) at Serine 897, which in turn phosphorylates RAD51 at Tyrosine 315, a key DNA repair protein involved in homologous recombination. ConclusionsWe uncover TAK1 as a critical mediator in maintaining genomic integrity and highlights its potential as a therapeutic target to induce an inflamed TME that sensitizes PDAC to ICB.

cancer biology↗

bioRxiv2018

Conversion of a soluble protein into a potent chaperone in vivo

Protein-folding assistance and aggregation inhibition by cellular factors are largely understood in the context of molecular chaperones. As an alternative and complementary model, we previously proposed that, in general, soluble cellular macromolecules including chaperones with large excluded volume and surface charges exhibit the intrinsic chaperone activity to prevent aggregation of their connected polypeptides, irrespective of the connection types, and thus to aid productive protein folding. As a proof of concept, we here demonstrated that a model soluble protein with an inactive protease domain robustly exerted chaperone activity toward various proteins harboring a short protease-recognition tag of 7 residues in Escherichia coli. The chaperone activity of this protein was similar or even superior to that of representative E. coli chaperones in vivo. Furthermore, in vitro refolding experiments confirmed the in vivo results. Our findings revealed that a soluble protein exhibits the intrinsic chaperone activity, which is manifested, upon binding to aggregation-prone proteins. This study gives new insights into the ubiquitous chaperoning role of cellular macromolecules in protein-folding assistance and aggregation inhibition underlying the maintenance of protein solubility and proteostasis in vivo.

biochemistry↗