is a synthetic lethal interactor of in colonic epithelial cells.

Colorectal cancer (CRC) remains a leading cause of cancer mortality worldwide, with chromosome instability (CIN) present in approximately 85% of cases and associated with poor prognosis. Reduced expression of , a component of the SKP1-CUL1-F-box (SCF) E3 ubiquitin ligase complex, occurs in about one-third of CRCs and correlates with CIN, positioning as a potential therapeutic target. This study employed bioinformatics analyses, small interfering RNA (siRNA) screening, small molecule inhibition, and quantitative imaging (QuantIM) microscopy to identify synthetic lethal interactors of . Shallow deletions of in CRC patient samples was found to associate with decreased gene expression and adverse clinical outcomes. Targeted silencing or pharmacological inhibition of CHEK1 using Prexasertib significantly reduced proliferation in -deficient cells. Mechanistic studies revealed that Prexasertib treatment increased DNA double-strand breaks and apoptosis specifically in -deficient cells. Furthermore, combining Prexasertib with 5-fluorouracil, a standard chemotherapeutic agent, produced a synergistic killing effect. These findings establish a novel synthetic lethal relationship between and , suggesting that CHEK1 inhibition may provide a targeted therapeutic strategy for CRC patients with deficiencies, and highlighting the broader potential of exploiting SCF complex alterations in CRC therapy.