Finding MYCure

Identification of 5-Thiocyanatothiazol-2-amines Disrupting WDR5-MYC Protein-Protein Interactions

MYC amplification is frequently observed in approximately 50% of human cancers, rendering it a highly desired anticancer target. Given the challenge of direct pharmacological inhibiting of MYC, impairing the interaction of MYC and its key cofactor WDR5 has been proposed as a promising strategy for MYC-driven cancer treatment. Herein, we report the discovery of 5-thiocyanatothiazol-2-amines that disrupt the WDR5-MYC interaction. Hit fragments were initially identified in a fluorescence polarization (FP)-based screening of an in-house library, and structural-activity relationship exploration resulted in the lead compounds 4m and 4o with potent inhibitory activities on WDR5-MYC interaction (K i = 2.4 μM for 4m; K i = 1.0 μM for 4o). These compounds were further validated via differential scanning fluorimetry (DSF) and coimmunoprecipitation (Co-IP). Moreover, 4m and 4o exhibited good cellular activities with the IC50 values at the micromolar level (IC50 = 0.71-7.40 μM) against multiple MYC-driven cancer cell lines. Our findings afforded a potential small molecule blocking the WDR5-MYC interaction.

Modes of Action of a Novel c-MYC Inhibiting 1,2,4-Oxadiazole Derivative in Leukemia and Breast Cancer Cells

The c-MYC oncogene regulates multiple cellular activities and is a potent driver of many highly aggressive human cancers, such as leukemia and triple-negative breast cancer. The oxadiazole class of compounds has gained increasing interest for its anticancer activities. The aim of this study was to investigate the molecular modes of action of a 1,2,4-oxadiazole derivative (ZINC15675948) as a c-MYC inhibitor. ZINC15675948 displayed profound cytotoxicity at the nanomolar range in CCRF-CEM leukemia and MDA-MB-231-pcDNA3 breast cancer cells. Multidrug-resistant sublines thereof (i.e., CEM/ADR5000 and MDA-MB-231-BCRP) were moderately cross-resistant to this compound (<10-fold). Molecular docking and microscale thermophoresis revealed a strong binding of ZINC15675948 to c-MYC by interacting close to the c-MYC/MAX interface. A c-MYC reporter assay demonstrated that ZINC15675948 inhibited c-MYC activity. Western blotting and qRT-PCR showed that c-MYC expression was downregulated by ZINC15675948. Applying microarray hybridization and signaling pathway analyses, ZINC15675948 affected signaling routes downstream of c-MYC in both leukemia and breast cancer cells as demonstrated by the induction of DNA damage using single cell gel electrophoresis (alkaline comet assay) and induction of apoptosis using flow cytometry. ZINC15675948 also caused G2/M phase and S phase arrest in CCRF-CEM cells and MDA-MB-231-pcDNA3 cells, respectively, accompanied by the downregulation of CDK1 and p-CDK2 expression using western blotting. Autophagy induction was observed in CCRF-CEM cells but not MDA-MB-231-pcDNA3 cells. Furthermore, microarray-based mRNA expression profiling indicated that ZINC15675948 may target c-MYC-regulated ubiquitination, since the novel ubiquitin ligase (ELL2) was upregulated in the absence of c-MYC expression. We propose that ZINC15675948 is a promising natural product-derived compound targeting c-MYC in c-MYC-driven cancers through DNA damage, cell cycle arrest, and apoptosis.

MYC Inhibition Halts Metastatic Breast Cancer Progression by Blocking Growth, Invasion, and Seeding

MYC's role in promoting tumorigenesis is beyond doubt, but its function in the metastatic process is still controversial. Omomyc is a MYC dominant negative that has shown potent antitumor activity in multiple cancer cell lines and mouse models, regardless of their tissue of origin or driver mutations, by impacting on several of the hallmarks of cancer. However, its therapeutic efficacy against metastasis has not been elucidated yet. Here we demonstrate for the first time that MYC inhibition by transgenic Omomyc is efficacious against all breast cancer molecular subtypes, including triple-negative breast cancer, where it displays potent antimetastatic properties both in vitro and in vivo. Importantly, pharmacologic treatment with the recombinantly produced Omomyc miniprotein, recently entering a clinical trial in solid tumors, recapitulates several key features of expression of the Omomyc transgene, confirming its clinical applicability to metastatic breast cancer, including advanced triple-negative breast cancer, a disease in urgent need of better therapeutic options.

Significance

While MYC role in metastasis has been long controversial, this manuscript demonstrates that MYC inhibition by either transgenic expression or pharmacologic use of the recombinantly produced Omomyc miniprotein exerts antitumor and antimetastatic activity in breast cancer models in vitro and in vivo, suggesting its clinical applicability.

Cell-penetrating peptides in protein mimicry and cancer therapeutics

Extensive research has been undertaken in the pursuit of anticancer therapeutics. Many anticancer drugs require specificity of delivery to cancer cells, whilst sparing healthy tissue. Cell-penetrating peptides (CPPs), now well established as facilitators of intracellular delivery, have in recent years advanced to incorporate target specificity and thus possess great potential for the targeted delivery of anticancer cargoes. Though none have yet been approved for clinical use, this novel technology has already entered clinical trials. In this review we present CPPs, discuss their classification, mechanisms of cargo internalization and highlight strategies for conjugation to anticancer moieties including their incorporation into therapeutic proteins. As the mainstay of this review, strategies to build specificity into tumor targeting CPP constructs through exploitation of the tumor microenvironment and the use of tumor homing peptides are discussed, whilst acknowledging the extensive contribution made by CPP constructs to target specific protein-protein interactions integral to intracellular signaling pathways associated with tumor cell survival and progression. Finally, antibody/antigen CPP conjugates and their potential roles in cancer immunotherapy and diagnostics are considered. In summary, this review aims to harness the potential of CPP-aided drug delivery for future cancer therapies and diagnostics whilst highlighting some of the most recent achievements in selective delivery of anticancer drugs, including cytostatic drugs, to a range of tumor cells both in vitro and in vivo.

The long journey to bring a Myc inhibitor to the clinic

The oncogene Myc is deregulated in the majority of human tumors and drives numerous hallmarks of cancer. Despite its indisputable role in cancer development and maintenance, Myc is still undrugged. Developing a clinical inhibitor for Myc has been particularly challenging owing to its intrinsically disordered nature and lack of a binding pocket, coupled with concerns regarding potentially deleterious side effects in normal proliferating tissues. However, major breakthroughs in the development of Myc inhibitors have arisen in the last couple of years. Notably, the direct Myc inhibitor that we developed has just entered clinical trials. Celebrating this milestone, with this Perspective, we pay homage to the different strategies developed so far against Myc and all of the researchers focused on developing treatments for a target long deemed undruggable.

An "-omycs" Toolbox to Work with MYC

The MYC transcription factor coordinates a wide range of intra- and extracellular processes associated with tissue proliferation and regeneration. While these processes are typically tightly regulated in physiological conditions, they become deregulated in cancer, where MYC is oncogenically activated.The last decade has seen MYC progress from a renowned undruggable target to a hot topic in the cancer therapy field, as proof emerged from mouse models that its inhibition constitutes an effective and broadly applicable approach to fight cancer. However, there are several aspects of MYC biology that still appear to be elusive and maintain the interest in further studying this intriguing protein. Since MYC's discovery, more than four decades ago, multiple strategies have been developed to study it, related to the many and varied facets of its biology. This new version of The Myc gene: Methods and Protocols provides valuable tips from key "inhabitants of the MYC world," which significantly increase the reach of our investigative tools to shed light on the mysteries still surrounding MYC.