# Unraveling the Impact of KRAS Accessory Proteins on Oncogenic Signaling Pathways

## TL;DR

This study identifies key proteins that regulate KRAS signaling in cancer cells, offering new therapeutic strategies to improve treatment effectiveness.

## Contribution

The study reveals distinct, non-redundant roles of KRAS accessory proteins in oncogenic signaling, suggesting novel drug targets.

## Key findings

- Knocking out GAL3 and PDEδ significantly reduced MAPK and PI3K-AKT signaling and cancer cell proliferation.
- SHOC2 selectively disrupted the MAPK pathway, while IQGAP1 knockout increased PI3K-AKT signaling.
- Targeting GAL3 and PDEδ could overcome resistance to current KRAS inhibitors by suppressing compensatory signaling.

## Abstract

What are the main findings?
Target Potency: Knocking out GAL3 and PDEδ significantly impaired MAPK signaling and reduced AKT-related signaling. GAL3 primarily impacted the mTORC2-AKT pathway, and PDEδ inhibited the mTORC2-AKT and PI3K-AKT pathways. This led to a substantial reduction in cancer cell proliferation.Pathway Specificity: SHOC2 selectively disrupted the MAPK pathway, and IQGAP1 knockout increased PI3K-AKT signaling. These results demonstrate that these accessory proteins have distinct, non-redundant roles in KRAS regulation.

Target Potency: Knocking out GAL3 and PDEδ significantly impaired MAPK signaling and reduced AKT-related signaling. GAL3 primarily impacted the mTORC2-AKT pathway, and PDEδ inhibited the mTORC2-AKT and PI3K-AKT pathways. This led to a substantial reduction in cancer cell proliferation.

Pathway Specificity: SHOC2 selectively disrupted the MAPK pathway, and IQGAP1 knockout increased PI3K-AKT signaling. These results demonstrate that these accessory proteins have distinct, non-redundant roles in KRAS regulation.

What is the implication of the main finding?
New Therapeutic Avenues: GAL3 and PDEδ are promising candidates for combinatorial drug development and could overcome the limitations of current direct KRAS inhibitors.Overcoming Resistance: Targeting these modulators could suppress the compensatory signaling that contributes to resistance to KRAS-targeted therapies.

New Therapeutic Avenues: GAL3 and PDEδ are promising candidates for combinatorial drug development and could overcome the limitations of current direct KRAS inhibitors.

Overcoming Resistance: Targeting these modulators could suppress the compensatory signaling that contributes to resistance to KRAS-targeted therapies.

The oncogene KRAS drives tumor growth by activating pathways such as MAPK and PI3K-AKT in a constitutive manner. Although direct KRAS inhibitors exist, they are often limited in clinical use due to therapeutic resistance and toxicity. Therefore, alternative combinatorial therapeutic strategies are urgently needed. This study examined the knockout of five KRAS-related proteins—galectin-3 (GAL3), phosphodiesterase delta (PDEδ), nucleophosmin (NPM1), IQ motif-containing GTPase-activating protein 1 (IQGAP1), and SHOC2—using CRISPR-Cas9 in adenocarcinoma cell lines harboring the KRAS(G12V) oncogenic mutation, as well as in the noncancerous HEK-293 cell line. These proteins act as critical modulators that regulate KRAS activity, cellular localization, and that of its downstream signaling components. We analyzed the downstream activation of ERK and AKT kinases and evaluated subsequent cancer cell proliferation. Knockout of GAL3 and PDEδ was highly effective, significantly reducing MAPK and PI3K-AKT pathway activity and substantially impairing cell proliferation. SHOC2 knockout selectively and potently disrupted MAPK activation, while NPM1 knockout resulted in the complex, reciprocal modulation of the two major pathways. Notably, knocking out IQGAP1 enhanced PI3K–AKT and mTORC2–AKT signaling without affecting the MAPK pathway. These distinct modulatory roles highlight the non-redundant functions of the accessory proteins. In conclusion, our findings establish GAL3 and PDEδ, two KRAS-associated proteins, as promising combinatorial drug targets. Targeting these modulators provides an effective alternative strategy to overcome resistance mechanisms and enhance the clinical utility of existing KRAS inhibitors.