Identification of Ras-degrading small molecules that inhibit the transformation of colorectal cancer cells independent of β-catenin signaling

Abstract

Although the development of drugs that control Ras is an emerging topic in cancer therapy, no clinically applicable drug is currently available. We have previously utilized knowledge of the Wnt/β-catenin signaling-dependent mechanism of Ras protein stability regulation to identify small molecules that inhibit the proliferation and transformation of various colorectal cancer (CRC) cells via degradation of both β-catenin and Ras. Due to the absence of Ras degradation in cells expressing a nondegradable mutant form of β-catenin and the need to determine an alternative mechanism of Ras degradation, we designed a cell-based system to screen compounds that degrade Ras independent of the Wnt/β-catenin signaling pathway. A cell-based high-content screening (HCS) system that monitors the levels of EGFP-K-RasG12V was established using HCT-116 cells harboring a nondegradable mutant CTNNB1 (ΔS45). Through HCS of a chemical library composed of 10,000 compounds and subsequent characterization of hits, we identified several compounds that degrade Ras without affecting the β-catenin levels. KY7749, one of the most effective compounds, inhibited the proliferation and transformation of CRC cells, especially KRAS-mutant cells that are resistant to the EGFR monoclonal antibody cetuximab. Small molecules that degrade Ras independent of β-catenin may able to be used in treatments for cancers caused by aberrant EGFR and Ras.

WDR76 degrades RAS and suppresses cancer stem cell activation in colorectal cancer

“…These results suggest RAS destabilization as a pathophysiologic strategy to overcome the limitations of treating oncogenic K-RAS-driven CRC [16]. The recent identification of a small molecule that degrades RAS independently of the Wnt/β-catenin pathway and suppresses the transformation and proliferation of CRC cells harboring non-degradable β-catenin indicates the existence of an alternative way for RAS stability regulation which plays important roles in CRC tumorigenesis [18]. Direct degradation of RAS to suppress oncogenic K-RAS-mediated enhancement of CSC activation may provide a novel approach to selectively target CSCs that contribute to cancer progression.…”

“…Nevertheless, the role of RAS stabilization in ISC and CSC activation has not been fully investigated. In addition to the regulation by Wnt/β-catenin signaling, a recent study revealed an alternative route to directly target RAS stability [18].…”

Droplet Combinations: A Scalable Microfluidic Platform for Biochemical Assays

“…A typical HTS system, PerkinElmer's Janus Automated Workstation is widely used in industry for drug screening. [29][30][31] The Janus typically produces CVs of 3.8% using the blowout method with VersaTip Fixed Tips (PerkinElmer), dispensing 1 μL of single-fluid deionized water. 32 The CV of 4.7% using the GST is inferior to the CV of the PerkinElmer technology, but the authors are confident that with technical improvements the GST can achieve similar if not better CVs.…”

Targeting KRAS in NSCLC: Old Failures and New Options for “Non-G12c” Patients

“…This study showed that both molecules cause RAS degradation, but K19 DARPins inhibit cell proliferation without interfering with wild-type KRAS cells. Moreover, Shin et al evaluated a novel RAS inhibitor, KY7749, that is able to degradate KRAS G12V in a beta-catenin-independent manner in in vitro colorectal cancer models [ 97 ].…”