Targeting Kinase Suppressor of Ras 1 (KSR1) for Cancer Therapy.

Carcinogenesis is driven by aberrant activation of molecular signaling pathways governing cell proliferation, apoptosis, and differentiation. Among these, the RAS/RAF/MEK/ERK (RAS/MAPK) cascade is one of the most frequently dysregulated oncogenic pathways, driving tumor initiation and progression across diverse cancer types. Although inhibitors of BRAF and MEK have achieved clinical success in selected malignancies, adaptive resistance often undermines therapeutic durability. This has spurred interest in alternative nodes within the pathway. The kinase suppressor of Ras (KSR) is a scaffold protein that organizes RAF, MEK, and ERK into functional complexes, ensuring efficient and sustained signal transmission. Once regarded as a passive structural component, KSR1 is now recognized as an active regulator of pathway dynamics. Emerging evidence indicates that KSR1 overexpression promotes cancer cell proliferation and survival, while genetic or pharmacologic inhibition of KSR1 attenuates RAS/MAPK signaling and suppresses tumor growth in preclinical models. In this review, we provide a comprehensive overview of accessory and scaffold proteins modulating the RAS/MAPK pathway, with a particular focus on KSR1. We highlight its structural and functional properties, summarize preclinical evidence for KSR1-targeted interventions, and discuss its therapeutic potential in cancer, with emphasis on hepatocellular carcinoma (HCC).