BioProject

Ubiquitylation is pivotal in regulating cellular responses, with its aberration implicated in tumor immune evasion. More...

Ubiquitylation is pivotal in regulating cellular responses, with its aberration implicated in tumor immune evasion. However, the impact of ubiquitin-conjugating enzymes (E2s) on this evasion remains unclear. Here, we employ a systematic approach to demonstrate that in pancreatic ductal carcinoma (PDAC), the inflammatory microenvironment induces overexpression of the E2 enzyme UBE2D3, contributing to tumor progression through non-oncogene codependent disorders. Through gene expression analyses and functional investigations, we elucidate a mechanism wherein cancer cells evade T cell immune responses by UBE2D3 binding to the ubiquitin ligase KLHL13 to co-ubiquitinate TAP2. This K63-linkage ubiquitination at the lysine 245 site of TAP2 impedes antigenic peptide transport by the TAP1/TAP2 complex, hindering p-MHC assembly and presentation in cancer cells. We demonstrate that genetic inhibition of UBE2D3 enhances tumor-specific CD8+ T cell proliferation and extends effector-memory-like phenotypes. Building on this, we develop a small-molecule inhibitor, QX-6, targeting the active site of UBE2D3 to disrupt its function. Pharmacologic inhibition of UBE2D3 blocks the ubiquitylation of antigen presentation-related substrates, leading to increased p-MHC presentation by cancer cells and reduced T cell exhaustion. Using immunocompetent and humanized models, we elucidate the therapeutic efficacy of targeting UBE2D3. Furthermore, we evaluate the synergistic anti-tumor effects of QX-6 in combination with KRAS-targeted TCR-T cell immunotherapy. In summary, our study reveals a post-translational modification mechanism wherein the intracellular checkpoint UBE2D3 regulates the TAP2 switch to control cancer cell evasion of CTLs, presenting a potential immunotherapeutic strategy to improve PDAC treatment outcomes. Overall design: For single cell sequencing, C57/BL6 mice bearing KPC-shScramble or KPC-shUBE2D3-1 tumors for 30 d were euthanized. Three tumors from the same group were pooled to prepare single-cell suspension for isolating enough tumor-infiltrating CD8+ T cells. These cells were isolated by FCM, selecting live, single cells expressing CD45, CD3, and CD8. Less...