A review on Liquid-Liquid Phase Separation (LLPS) as a Druggable Phenomenon: Small-Molecule Modulators of Oncogenic Biomolecular Condensates

Abstract

Liquid-liquid phase separation is a key biological mechanism used to facilitate subcellular compartmentation leading to the formation of membrane-less compartments. Cancer cells, in malignant conditions, recruit this thermodynamic process to form “onco-condensates” – dense, multicomponent, macromolecular hubs that concentrate onco-genic transcription factors (e.g., c-Myc, EWS-FLI1, mutant ENL), sequester tumor suppressors (e.g., p53) and hyper-activate super-enhancer-driven transcriptional circuitry. Conventional medicinal chemistry strategies, which are deeply entrenched in the “lock-and-key” paradigm of targeting rigid (and predominantly hydrophobic) binding pockets on proteins, have historically failed to hit the intrinsically disordered regions (IDRs) of proteins, leading to their classification of major oncogenic drivers as “undruggable.” The current review attempts to integrate the biophysical “chemical grammar” of phase boundaries with the rational development of small molecules that selectively modulate these droplets via hit-and-run mechanisms. We analyze the intermolecular forces—such as π-π stacking, cation- π interactions, and transient electrostatic networks—that determine the partitioning coefficient (Kp) of synthetic molecules into the dense phase. Moreover, we classify maximal therapeutic strategies into 3 further chemical actions either condensate disrupter, hardener (liquid-to-solid), selective partitioners (droplet drugging). Ultimately, we offer an analytical description of the basic screening tools that are required with respect to Fluorescence Recovery After Photobleaching (FRAP) kinetics, in vitro turbidity assays. This multidisciplinary manuscript combines cellular signaling networks with coordination and natural product medicinal chemistry in a modern roadmap to drug the un-enveloped proteome to avoid acquired chemotherapy resistance.