Lysine-52 stabilizes the MYC oncoprotein through an SCFFbxw7-independent mechanism

Control of protein stability by post-translational modifications

Post-translational modifications (PTMs) can occur on specific amino acids localized within regulatory domains of target proteins, which control a protein's stability. These regions, called degrons, are often controlled by PTMs, which act as signals to expedite protein degradation (PTM-activated degrons) or to forestall degradation and stabilize a protein (PTM-inactivated degrons). We summarize current knowledge of the regulation of protein stability by various PTMs. We aim to display the variety and breadth of known mechanisms of regulation as well as highlight common themes in PTM-regulated degrons to enhance potential for identifying novel drug targets where druggable targets are currently lacking.

Therapeutic targeting of "undruggable" MYC

c-MYC controls global gene expression and regulates cell proliferation, cell differentiation, cell cycle, metabolism and apoptosis. According to some estimates, MYC is dysregulated in ≈70% of human cancers and strong evidence implicates aberrantly expressed MYC in both tumor initiation and maintenance. In vivo studies show that MYC inhibition elicits a prominent anti-proliferative effect and sustained tumor regression while any alteration on healthy tissue remains reversible. This opens an exploitable window for treatment that makes MYC one of the most appealing therapeutic targets for cancer drug development. This review describes the main functional and structural features of the protein structure of MYC and provides a general overview of the most relevant or recently identified interactors that modulate MYC oncogenic activity. This review also summarizes the different approaches aiming to abrogate MYC oncogenic function, with a particular focus on the prototype inhibitors designed for the direct and indirect targeting of MYC.

Targeting Myc Interacting Proteins as a Winding Path in Cancer Therapy

MYC, as a well-known oncogene, plays essential roles in promoting tumor occurrence, development, invasion and metastasis in many kinds of solid tumors and hematologic neoplasms. In tumors, the low expression and the short half-life of Myc are reversed, cause tumorigenesis. And proteins that directly interact with different Myc domains have exerted a significant impact in the process of Myc-driven carcinogenesis. Apart from affecting the transcription of Myc target genes, Myc interaction proteins also regulate the stability of Myc through acetylation, methylation, phosphorylation and other post-translational modifications, as well as competitive combination with Myc. In this review, we summarize a series of Myc interacting proteins and recent advances in the related inhibitors, hoping that can provide new opportunities for Myc-driven cancer treatment.

MYC, MYCL, and MYCN as therapeutic targets in lung cancer

Introduction: Lung cancer is the leading cause of cancer-related mortality globally. Despite recent advances with personalized therapies and immunotherapy, the prognosis remains dire and recurrence is frequent. Myc is an oncogene deregulated in human cancers, including lung cancer, where it supports tumorigenic processes and progression. Elevated Myc levels have also been associated with resistance to therapy.Areas covered: This article summarizes the genomic and transcriptomic studies that compile evidence for (i) MYC, MYCN, and MYCL amplification and overexpression in lung cancer patients, and (ii) their prognostic significance. We collected the most recent literature regarding the development of Myc inhibitors where the emphasis is on those inhibitors tested in lung cancer experimental models and their potential for future clinical application.Expert opinion: The targeting of Myc in lung cancer is potentially an unprecedented opportunity for inhibiting a key player in tumor progression and maintenance and therapeutic resistance. Myc inhibitory strategies are on the path to their clinical application but further work is necessary for the assessment of their use in combination with standard treatment approaches. Given the role of Myc in immune suppression, a significant opportunity may exist in the combination of Myc inhibitors with immunotherapies.

Sublytic C5b-9 induces proliferation of glomerular mesangial cells via ERK5/MZF1/RGC-32 axis activated by FBXO28-TRAF6 complex

Mesangioproliferative glomerulonephritis (MsPGN) is characterized by the proliferation of glomerular mesangial cells (GMCs) and accumulation of extracellular matrix (ECM), followed by glomerulosclerosis and renal failure of patients. Although our previous studies have demonstrated that sublytic C5b‐9 complex formed on the GMC membrane could trigger GMC proliferation and ECM expansion of rat Thy‐1 nephritis (Thy‐1N) as an animal model of MsPGN, their mechanisms are still not fully elucidated. In the present studies, we found that the levels of response gene to complement 32 (RGC‐32), myeloid zinc finger 1 (MZF1), phosphorylated extracellular signal‐regulated kinase 5 (phosphorylated ERK5, p‐ERK5), F‐box only protein 28 (FBXO28) and TNF receptor‐associated factor 6 (TRAF6) were all markedly up‐regulated both in the renal tissues of rats with Thy‐1N (in vivo) and in the GMCs upon sublytic C5b‐9 stimulation (in vitro). Further in vitro experiments revealed that up‐regulated FBXO28 and TRAF6 could form protein complex binding to ERK5 and enhance ERK5 K63‐ubiquitination and subsequent phosphorylation. Subsequently, ERK5 activation contributed to MZF1 expression and MZF1‐dependent RGC‐32 up‐regulation, finally resulting in GMC proliferative response. Furthermore, the MZF1‐binding element within RGC‐32 promoter and the functions of FBXO28 domains were identified. Additionally, knockdown of renal FBXO28, TRAF6, ERK5, MZF1 and RGC‐32 genes respectively markedly reduced GMC proliferation and ECM production in Thy‐1N rats. Together, these findings indicate that sublytic C5b‐9 induces GMC proliferative changes in rat Thy‐1N through ERK5/MZF1/RGC‐32 axis activated by the FBXO28‐TRAF6 complex, which might provide a new insight into MsPGN pathogenesis.