DHHC7 palmitoylates KRAS4A and promotes mutant KRAS-driven pancreatic cancers

Abstract

KRAS mutations underlie many human cancers. While inhibitors such as Sotorasib and Adagrasib targeting KRAS mutants have shown promise, additional strategies are required to address the broader spectrum of KRAS-driven cancers, particularly those displaying drug resistance. Thus, there is a need to better understand KRAS signaling and develop new therapeutic strategies. Here we show that KRAS4A is palmitoylated on Cys180 by a palmitoyl transferase, DHHC7 (gene name ZDHHC7). Palmitoylation promotes KRAS4A plasma membrane localization, and more importantly, nanoclustering. This in turn promotes the activation of ARAF and RAF1, but not BRAF. DHHC7 and KRAS4A Cys180 palmitoylation are important for the normal and anchorage independent growth of pancreatic cancer cell lines. Depletion of ZDHHC7 dramatically inhibits pancreatic tumor growth in mouse xenograft models. These studies provide new understandings about how palmitoylation regulates KRAS4A activity and suggest DHHC7 as a promising new target for KRAS mutant cancers.