Kinase suppressor of ras 1 (KSR1) regulates PGC1α and estrogen-related receptor α to promote oncogenic ras-dependent anchorage-independent growth

Kinase suppressGrowthor of ras 1 (KSR1) is a molecular scaffold of the Raf/MEK/extracellular signal-regulated kinase (ERK) cascade that enhances oncogenic Ras signaling. Here we show KSR1-dependent, but ERKindependent, regulation of metabolic capacity is mediated through the expression of peroxisome proliferatoractivated receptor gamma coactivator 1α (PGC1α) and estrogen-related receptor α (ERRα). This KSR1-regulated pathway is essential for the transformation of cells by oncogenic Ras. In mouse embryo fibroblasts (MEFs) expressing H-Ras^V12, ectopic PGC1α was sufficient to rescue ERRα expression, metabolic capacity, and anchorage-independent growth in the absence of KSR1. The ability of PGC1α to promote anchorageindependent growth required interaction with ERRα, and treatment with an inhibitor of ERRα impeded anchorage-independent growth. In contrast to PGC1α, the expression of constitutively active ERRα (CAERR α) was sufficient to enhance metabolic capacity but not anchorage-independent growth in the absence of KSR1. These data reveal KSR1-dependent control of PGC1α- and ERRα-dependent pathways that are necessary and sufficient for signaling by oncogenic H-Ras^V12 to regulate metabolism and anchorage-independent growth, providing novel targets for therapeutic intervention.