Nearly 50% of human malignancies exhibit unregulated RAS-ERK signaling; inhibiting it is a valid strategy for antineoplastic intervention. Upon activation, ERK dimerize, which is essential for ERK extranuclear, but not for nuclear, signaling. Here, we describe a small molecule inhibitor for ERK dimerization that, without affecting ERK phosphorylation, forestalls tumorigenesis driven by RAS-ERK pathway oncogenes. This compound is unaffected by resistance mechanisms that hamper classical RAS-ERK pathway inhibitors. Thus, ERK dimerization inhibitors provide the proof of principle for two understudied concepts in cancer therapy: (1) the blockade of sub-localization-specific sub-signals, rather than total signals, as a means of impeding oncogenic RAS-ERK signaling and (2) targeting regulatory protein-protein interactions, rather than catalytic activities, as an approach for producing effective antitumor agents.

Recurrence appears to be more frequent and earlier after TSS in patients with USP8 mutant corticotroph tumours.

Lysine methylation has been traditionally associated with histones and epigenetics. Recently, lysine methyltransferases and demethylases – which are involved in methylation of non‐histone substrates – have been frequently found deregulated in human tumours. In this realm, a new discovery has unveiled the methyltransferase SMYD3 as an enhancer of Ras‐driven cancer. SMYD3 is up‐regulated in different types of tumours. SMYD3‐mediated methylation of MAP3K2 increases mutant K‐Ras‐induced activation of ERK1/2. Methylation of MAP3K2 prevents it from binding to the phosphatase PP2A, thereby impeding the impact of this negative regulator on Ras‐ERK1/2 signals, leading to the formation of lung and pancreatic adenocarcinomas. Furthermore, depletion of SMYD3 synergises with a MEK inhibitor, currently in clinical trials, to block Ras‐driven pancreatic neoplasia. These results underscore the importance of lysine methylation in the regulation of signalling pathways relevant for tumourigenesis and endorse the development of drugs targeting unregulated lysine methylation as therapeutic agents in the struggle against cancer.