# Genetic and Pharmacological Manipulation of KSR in KRAS-driven Cancer

> **NIH NIH F30** · ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI · 2021 · $51,036

## Abstract

Project Summary: KRAS mutations are drivers of oncogenesis, and historically have been considered
“undruggable.” Consequentially, therapeutic approaches have focused on downstream effectors of the
mitogen-activated protein kinase (MAPK) pathway, including RAF, MEK, and ERK–though no approach has
led to an effective drug for KRAS-driven disease. However, genetic studies strongly support that the MAPK
signaling pathway is a critical dependency in KRAS-mutant cancers; so why do current MAPK drugs fail?
Recent studies suggest that these drugs are effective inhibitors of MAPK enzyme activity, yet fail due to
feedback mechanisms that rely on protein-protein interactions (PPIs) to maintain MAPK signaling even in the
presence of drug. My overarching hypothesis is that current MAPK inhibitors are limited by their inability to
effectively regulate critical PPIs among MAPK components. To test this hypothesis, I will alter critical PPIs by
modulating a MAPK scaffold termed Kinase Suppresor of Ras (KSR). In contrast to previous MAPK targets,
KSR is a pseudokinase that lacks catalytic activity, but serves as a scaffold protein to promote RAF and MEK
binding. Our group showed that a lead compound termed APS-2-79 binds to KSR2 at the ATP binding site
and synergizes with MEK inhibitors (MEKi) in KRAS-driven cell lines by impeding KSR’s interaction with RAF.
While useful as a tool for biochemical studies, APS-2-79 has several limitations including modest affinity and
selectivity for KSR. Moreover, the mechanism of KSR inhibitor (KSRi) synergy with MEKi in KRAS mutant cell
lines is not known, and may be the consequence of off target kinase inhibition instead of direct KSR targeting.
 To investigate the mechanism of KSRi synergy with MEK inhibitors, I aim to test the dependence of
KSRi synergy in KRAS mutant cells on KSR using genetic tools. I hypothesize that the synergy observed
between MEKi and KSRi in KRAS mutant cells is dependent on the availability of KSR’s ATP-binding pocket.
To test this hypothesis, I will use lentiviral vectors to overexpress KSR, +/- mutations in the ATP binding pocket
known to prevent compound binding. To further explore the importance of KSR in mediating RAS-MAPK
signaling, I also aim to induce targeted KSR degradation with small-molecule PROteolysis TArgeting
Chimeras (PROTACs) These small molecule tools simultaneously bind their protein targets and E3 ubiquitin
ligases, allowing for ubiquitination of the target and downstream proteolysis. I hypothesize that PROTAC
mediated KSR1 degradation will mimic genetic deletion studies supporting the importance of KSR1 for
oncogenic KRAS. My aims outline genetic and pharmacological approaches to investigate KSR inactivation as
a mechanism to exploit crucial PPIs within the KRAS-driven MAPK signaling pathway. Critical to this study are
the development of potent and specific next-generation KSRi analogs and precise genetic tools for target
validation. Ultimately this training proposal nurtures ski...

## Key facts

- **NIH application ID:** 10207543
- **Project number:** 5F30CA232454-04
- **Recipient organization:** ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
- **Principal Investigator:** Alexander Real
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $51,036
- **Award type:** 5
- **Project period:** 2018-07-02 → 2022-07-01

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10207543

## Citation

> US National Institutes of Health, RePORTER application 10207543, Genetic and Pharmacological Manipulation of KSR in KRAS-driven Cancer (5F30CA232454-04). Retrieved via AI Analytics 2026-06-01 from https://api.ai-analytics.org/grant/nih/10207543. Licensed CC0.

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