DPY30 Sticks a Fork in PDAC Immunity.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, with limited therapeutic options and poor responsiveness to immune checkpoint blockade (ICB). Emerging evidence links genome instability and replication stress to the activation of cyclic GMP-AMP synthase (cGAS)/STING-mediated antitumor immunity, suggesting that regulators of replication stress may modulate immunotherapeutic outcomes. In this issue of Cancer Research, Citron and colleagues identify dumpy-30 (DPY30), a component of the WRAD complex within SET1/MLL family histone H3 lysine 4 (H3K4) methyltransferases, as a suppressor of replication stress-induced immune activation in PDAC. DPY30 loss compromises replication fork protection, leading to DNA damage and robust cGAS/STING activation. Consequently, DPY30-deficient PDAC tumors show enhanced immune cell infiltration, increased sensitivity to T cell-mediated killing, and an improved ICB response. Mechanistically, DPY30 localizes to replication forks where it promotes H3K4 and H3K9 methylation. How these changes protect from replication stress is yet to be determined, and additional WRAD- and/or methylation-independent functions remain possible. Unlike the depletion of other WRAD members, loss of DPY30 does not disrupt global chromatin regulation, positioning DPY30 as a replication fork-specific chromatin effector, inhibition of which may amplify antitumor immunity while sparing essential transcriptional programs. Targeting DPY30 thus presents a promising strategy to potentiate immunotherapy responses in PDAC and potentially other malignancies. See related article by Citron et al., p. 2837.