Ubiquitination-Driven Reprogramming of Proteostasis in Metastasis.

Metastasis, the leading cause of cancer-related mortality, poses a fundamental proteostatic challenge, requiring rapid and precise proteome remodeling in response to stress. While ubiquitination is linked to protein degradation, our recent work uncovered a non-canonical, metastasis-promoting mechanism centered on DCAF12, a substrate receptor of the Cullin 4-RING ubiquitin ligase complex. DCAF12 mediates non-degradative ubiquitination of TRiC/CCT chaperonin subunits, allosterically activating the chaperonin to enhance its assembly, stability, and folding capacity. This ubiquitination-dependent activation circuit enables metastatic cells to efficiently fold and stabilize diverse pro-metastatic proteins, thereby facilitating dynamic proteome reprogramming. Herein, we present the DCAF12-TRiC/CCT axis as a central regulatory component of this adaptive response, explore its evolutionary basis, and propose DCAF12 as a prototype for a broader class of "DCAFome" regulators of chaperone function. This mechanistic understanding establishes a direct rationale for therapeutically targeting this axis to disrupt adaptive proteostasis. Moreover, we outline a therapeutic paradigm termed "proteostatic stress creation." This framework encompasses a spectrum of strategies, from precision protein-protein interaction inhibitors to state-selective degraders of DCAF12 or its ubiquitinated chaperonin subunits. These approaches can potentially disrupt the DCAF12-TRiC/CCT axis, thereby undermining the proteostatic resilience that sustains advanced cancers.