# KRAS mutation-selective requirement for ACSS2 in colorectal adenoma formation

## TL;DR

This study shows that different KRAS mutations in colorectal cancer affect cholesterol and lipid pathways differently, with G12V mutations relying on ACSS2 for tumor growth.

## Contribution

The study reveals a mutation-selective requirement for ACSS2 in G12V KRAS-driven colorectal adenoma formation.

## Key findings

- Transcriptomic and proteomic analyses show distinct signaling properties between KRAS mutants, particularly in cholesterol and lipid regulation.
- G12V mutant cells exhibit increased SREBP1 and mTORC1 activation, leading to upregulated lipid metabolism.
- ACSS2 inhibition sensitizes G12V cells to MEK inhibition and is critical for early tumor development in G12V mutants.

## Abstract

Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and are associated with poor prognosis and resistance to therapy. There is a substantial diversity of KRAS mutant alleles observed in CRC. Emerging clinical and experimental analysis of common KRAS mutations suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although there is some evidence to suggest biological differences between mutant KRAS alleles, these are yet to be fully elucidated. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous Kras mutants. Here, we generated Kras isogenic Apc−/− mouse colon epithelial cell lines using CRISPR-driven genome editing by altering the original G12D Kras allele to G12V, G12R, or G13D. We utilized these cell lines to perform transcriptomic and proteomic analysis to compare different signaling properties between these mutants. Both screens indicate significant differences in pathways relating to cholesterol and lipid regulation that we validated with targeted metabolomic measurements and isotope tracing. We found that these processes are upregulated in G12V lines through increased expression of nuclear SREBP1 and higher activation of mTORC1. G12V cells showed higher expression of ACSS2 and ACSS2 inhibition sensitized G12V cells to MEK inhibition. Finally, we found that ACSS2 plays a crucial role early in the development of G12V mutant tumors, in contrast to G12D mutant tumors. These observations highlight differences between KRAS mutant cell lines in their signaling properties. Further exploration of these pathways may prove to be valuable for understanding how specific KRAS mutants function, and identification of novel therapeutic opportunities in CRC.