Inhibition Of MYC Research Articles

Crystal Structures and Nuclear Magnetic Resonance Studies of the Apo Form of the c-MYC:MAX bHLHZip Complex Reveal a Helical Basic Region in the Absence of DNA.

The c-MYC transcription factor is a master regulator of cell growth and proliferation and is an established target for cancer therapy. This basic helix–loop–helix Zip protein forms a heterodimer with its obligatory partner MAX, which binds to DNA via the basic region. Considerable research efforts are focused on targeting the heterodimerization interface and the interaction of the complex with DNA. The only available crystal structure is that of a c-MYC:MAX complex artificially tethered by an engineered disulfide linker and prebound to DNA. We have carried out a detailed structural analysis of the apo form of the c-MYC:MAX complex, with no artificial linker, both in solution using nuclear magnetic resonance (NMR) spectroscopy and by X-ray crystallography. We have obtained crystal structures in three different crystal forms, with resolutions between 1.35 and 2.2 Å, that show extensive helical structure in the basic region. Determination of the α-helical propensity using NMR chemical shift analysis shows that the basic region of c-MYC and, to a lesser extent, that of MAX populate helical conformations. We have also assigned the NMR spectra of the c-MYC basic helix–loop–helix Zip motif in the absence of MAX and showed that the basic region has an intrinsic helical propensity even in the absence of its dimerization partner. The presence of helical structure in the basic regions in the absence of DNA suggests that the molecular recognition occurs via a conformational selection rather than an induced fit. Our work provides both insight into the mechanism of DNA binding and structural information to aid in the development of MYC inhibitors.

Recurrent MSCE116K mutations in ALK-negative anaplastic large cell lymphoma

AbstractAnaplastic large cell lymphomas (ALCLs) represent a relatively common group of T-cell non-Hodgkin lymphomas (T-NHLs) that are unified by similar pathologic features but demonstrate marked genetic heterogeneity. ALCLs are broadly classified as being anaplastic lymphoma kinase (ALK)+ or ALK−, based on the presence or absence of ALK rearrangements. Exome sequencing of 62 T-NHLs identified a previously unreported recurrent mutation in the musculin gene, MSCE116K, exclusively in ALK− ALCLs. Additional sequencing for a total of 238 T-NHLs confirmed the specificity of MSCE116K for ALK− ALCL and further demonstrated that 14 of 15 mutated cases (93%) had coexisting DUSP22 rearrangements. Musculin is a basic helix-loop-helix (bHLH) transcription factor that heterodimerizes with other bHLH proteins to regulate lymphocyte development. The E116K mutation localized to the DNA binding domain of musculin and permitted formation of musculin–bHLH heterodimers but prevented their binding to authentic target sequence. Functional analysis showed MSCE116K acted in a dominant-negative fashion, reversing wild-type musculin-induced repression of MYC and cell cycle inhibition. Chromatin immunoprecipitation–sequencing and transcriptome analysis identified the cell cycle regulatory gene E2F2 as a direct transcriptional target of musculin. MSCE116K reversed E2F2-induced cell cycle arrest and promoted expression of the CD30–IRF4–MYC axis, whereas its expression was reciprocally induced by binding of IRF4 to the MSC promoter. Finally, ALCL cells expressing MSCE116K were preferentially targeted by the BET inhibitor JQ1. These findings identify a novel recurrent MSC mutation as a key driver of the CD30–IRF4–MYC axis and cell cycle progression in a unique subset of ALCLs.

Novel synthetic tosyl chloride-berbamine regresses lethal MYC-positive leukemia by targeting CaMKIIγ/Myc axis

Proto-oncogene Myc, a key transcription factor, is frequently deregulated in human leukemia with aggressive and poor clinical outcome, but the development of MYC inhibitors remains challenging due to MYC helix-loop-helix topology lacking druggable domains. Here we describe a novel oral active small molecule analog of berbamine, tosyl chloride-berbamine (TCB), that efficiently eliminates MYC-positive leukemia in vitro and in vivo. Mechanistically, TCB potently reduced MYC protein by inhibiting CaMKIIγ, a critical enzyme that stabilizes MYC protein, and induces apoptosis of MYC-positive leukemia cells. In vivo, oral administration of TCB markedly eliminated lethal MYC-positive acute lymphoblastic leukemia (ALL) with well tolerability in orthotopic mouse model. Our studies identify CaMKIIγ/Myc axis as a valid target for developing small molecule-based new therapies for treating MYC-mediated leukemia and demonstrate that TCB is an orally active analog of berbamine that kills MYC-positive leukemia cells.

Finding MYCure

ABSTRACTInhibiting the nuclear protein MYC involved in the majority of human cancers has long been considered an impossible mission and several technical challenges have discouraged the development of MYC inhibitory strategies. Nevertheless, in our recent publication in Science Translational Medicine “Intrinsic cell-penetrating activity propels Omomyc from proof of concept to viable anti-MYC therapy”, we demonstrate for the first time the feasibility of pharmacological MYC inhibition in vitro and in vivo using an Omomyc-based mini-protein.

The MAP3K13-TRIM25-FBXW7α axis affects c-Myc protein stability and tumor development.

c-Myc (Myc) is a master transcription factor that is often deregulated and highly expressed by at least 50% of cancers. In many cases, Myc protein levels correlate with resistance to therapy and poor prognosis. However, effective direct inhibition of Myc by pharmacologic approaches has remained unachievable. Here, we identify MAP3K13 as a positive regulator of Myc to promote tumor development. Our findings show that MAP3K13 upregulation is predictive of poor outcomes in patients with hepatocellular carcinoma (HCC). Mechanistically, MAP3K13 phosphorylates the E3 ubiquitin ligase TRIM25 at Ser12 to decrease its polyubiquitination and proteasomal degradation. This newly stabilized TRIM25 then directly ubiquitinates Lys412 of FBXW7α, a core subunit of the SKP1-Cullin-F-box (SCF) ubiquitin ligase complex involved in Myc ubiquitination, thereby stabilizing Myc. Together, these results reveal a novel regulatory pathway that supervises Myc protein stability via the MAP3K13-TRIM25-FBXW7α signaling axis. In addition, they provide a potential therapeutic target in Myc over-expressing human cancers.

Indenoisoquinoline Topoisomerase Inhibitors Strongly Bind and Stabilize the MYC Promoter G-Quadruplex and Downregulate MYC.

MYC is one of the most important oncogenes and is overexpressed in the majority of cancers. G-Quadruplexes are noncanonical four-stranded DNA secondary structures that have emerged as attractive cancer-specific molecular targets for drug development. The G-quadruplex formed in the proximal promoter region of the MYC oncogene (MycG4) has been shown to be a transcriptional silencer that is amenable to small-molecule targeting for MYC suppression. Indenoisoquinolines are human topoisomerase I inhibitors in clinical testing with improved physicochemical and biological properties as compared to the clinically used camptothecin anticancer drugs topotecan and irinotecan. However, some indenoisoquinolines with potent anticancer activity do not exhibit strong topoisomerase I inhibition, suggesting a separate mechanism of action. Here, we report that anticancer indenoisoquinolines strongly bind and stabilize MycG4 and lower MYC expression levels in cancer cells, using various biochemical, biophysical, computer modeling, and cell-based methods. Significantly, a large number of active indenoisoquinolines cause strong MYC downregulation in cancer cells. Structure-activity relationships of MycG4 recognition by indenoisoquinolines are investigated. In addition, the analysis of indenoisoquinoline analogues for their MYC-inhibitory activity, topoisomerase I-inhibitory activity, and anticancer activity reveals a synergistic effect of MYC inhibition and topoisomerase I inhibition on anticancer activity. Therefore, this study uncovers a novel mechanism of action of indenoisoquinolines as a new family of drugs targeting the MYC promoter G-quadruplex for MYC suppression. Furthermore, the study suggests that dual targeting of MYC and topoisomerase I may serve as a novel strategy for anticancer drug development.

PB1648 THE CLINICAL RELEVANCE OF INDIRECT MYC INHIBITORS FOR PERSONALIZED T‐ALL TREATMENT

Background:Therapy refractory and relapsed T cell lymphoblastic leukemia (T‐ALL) is still one of the most common reasons for cancer related death in children. The current therapy option is stem cell transplantation, which is associated with many complications and therefore, targeted therapies with low toxicity profiles are urgently needed. The oncogenic transcription factor MYC is excellently suited as a therapeutic target as it has proven to be a potent driver for T‐ALL development. So far, direct inhibition of MYC is not possible due to its undruggable structure. Hence, inhibition of MYC can be achieved indirectly or by targeting synergistic pathways.Aims:The aim of our study is to identify major key regulators in MYC driven T‐ALL. Targeting synergistic pathways of MYC like the PI3K/AKT signalling pathway seems to be a promising strategy to precisely eliminate tumour cells without affecting healthy cells.Methods:We profiled several T‐ALL and a T cell lymphoma cell line model with a specific interest for genes implicated in MYC regulation on mRNA and protein level including major MYC regulator pathways like Notch‐signaling, Raf‐MEK‐ERK cascade, BRD4, protein folding and PI3K/AKT/mTOR pathway. In parallel, we designed a leukemia specific compound library (n = 180) of diverse phase I ‐ III inhibitors including clinically available chemotherapeutics, diverse kinase‐, HSP90‐, proteasome‐, HDAC‐ and BET inhibitors. Synergy studies were performed with preselected compounds in an 11 × 11 matrix.Results:Protein and mRNA profiling displayed a varying distribution of MYC expression, including its associated downstream and upstream signaling pathways. PTEN loss of function mutants (PTEN mut) are described to have an increased pAKT level due to PI3K dysregulation which has a stabilising effect on MYC, and besides that it has also been associated with a poor outcome in T‐ALL patients. Interestingly, PTEN mut expressing T‐ALL cell lines (MOLT4, HPBALL, JURKAT and SUPT1) shown a simultaneous hyper AKT phosphorylation (pAKT), whereas, PTEN wildtype (wt) cell lines (TALL1, HSB2, DND41 and PEER) exhibit remarkably low pAKT. However MYC expression did not strongly correlate with the PTEN/pAKT status. Therefore, we stratified high and low MYC expressing cell lines according to their PTEN mutational status. Thus, we screened the T‐ALL cell lines on our compound library, which covered major MYC regulatory pathways. Remarkably, specific classes of drugs, including PI3K/AKT/mTOR and Aurora kinase A inhibitors exhibited a promising drug profile in PTEN mut models, while MEK and ERK1/2 inhibitors were particularly potent in PTEN wt. These results were corroborated in a (PTEN wt) low MYC expressing T‐ALL1 cell line model, which showed an increased sensitivity toward Aurora Kinase A inhibitors when MYC was overexpressed. Furthermore, combination studies of PI3K inhibitors with the established indirect MYC inhibitors, e.g. BRD4 or Aurora kinase A inhibitors revealed an synergistic effect in PTEN mut when compared to PTEN wt expressing cell lines.Summary/Conclusion:The source of MYC overexpression is very heterogeneous because its maintenance is highly dependent upon many regulatory pathways. Knocking down the oncogenic transcription factor MYC via synergistic pathways is a promising strategy for targeted therapies in the future.

MYC as a therapeutic target for the treatment of triple-negative breast cancer.

e12550 Background: Despite intensive efforts, a validated targeted therapy for triple-negative breast cancer (TNBC) remains elusive. One of the most frequent genetic alterations identified in TNBC is amplification of the MYC gene which is found in > 60% of samples. The aim of this study was therefore to investigate the potential value of targeting MYC activation with the recently identified selective and high-affinity low molecular weight MYC inhibitor MYCMI-6, for the treatment of TNBC. Methods: Cell viability was determined using the MTT assay and apoptosis by flow cytometry using annexin V-propidium iodide staining. Results: Based on a panel of 13 breast cancer cell lines, IC50 values for inhibition of proliferation by MYCMI-6 ranged from 1.2 to 96.7 μM. Significantly lower IC50 values were found for TNBC than for non-TNBC cell lines (p = 0.04), i.e., TN cell lines were more sensitive to MYCMI-6 than non-TN cell lines. IC50 values for MYCMI-6 were compared with 2 older MYC inhibitors, i.e., 10058-F4 and KJ Pyr 9. Of these 3 inhibitors, the lowest IC50 values were found for MYCMI-6, i.e., MYCMI-6 was the most sensitive of the 3 inhibitors investigated (p < 0.0001 for MYCMI-6 versus both 10058-F4 and KJ Pyr 9). In addition to inhibiting cell proliferation, MYCMI-6 was found to induce apoptosis in a time and concentration-dependent manner in multiple breast cancer cell lines. A significant correlation was found between MYCMI-6 IC50 and induction of apoptosis ((p = 0.0499, r 2= 0.9026, n = 4), i.e., the lower the IC50 value, the greater the number of apoptotic cells present. This finding suggests that MYCMI-6 decreases cell proliferation by inducing apoptosis. Conclusions: We conclude that the MYC targeting compound, MYCMI-6 is a potential new treatment for TNBC.

Effects of SM08502, a novel, oral small-molecule inhibitor of Wnt pathway signaling, on gene expression and antitumor activity in colorectal cancer (CRC) models.

e15185 Background: Aberrant activation of Wnt signaling contributing to tumorigenesis is most commonly associated with CRC (90% harbor Wnt pathway mutations). SM08502, a novel, oral Wnt signaling pathway inhibitor, was evaluated in preclinical CRC models. Methods: In vitro Wnt signaling: assessed using TOPflash β-catenin/TCF reporter assay in SW480 human CRC cells. In vitro Wnt pathway gene expression: measured by qRT-PCR in SW480 and Wnt3a-stimulated cells (HEK-293T, IEC-6), and with the Nanostring Wnt pathway array (180 genes) across a panel of 16 CRC cell lines. In vitro cell proliferation: 17 CRC cell lines were used to test cell viability following treatment. In vivo antitumor activity: Oral SM08502 was tested in CRC mouse xenografts (SW480, HCT 116) and a PDX model over 20-21 days (QD, QOD). 24-hr pharmacodynamic (PD) analysis of Wnt pathway gene expression was done in SW480 tumor explants from mice following one 25 mg/kg dose. Results: SM08502 inhibited Wnt pathway signaling (EC50 = 46 nM) in SW480 cells. Wnt pathway gene expression was inhibited by SM08502 (0.3-3 µM) in Wnt3a-stimulated cells ( AXIN2, LEF1) and SW480 ( AXIN2, CTNNB1, LEF1, MYC, TCF7, TCF7L2) at 24 hrs ( P < .05 vs. vehicle) . Corresponding effects on protein expression were confirmed for all genes except CTNNB1, suggesting SM08502 acted independently of β-catenin. Nanostring array screening identified inhibition of LRP5, DVL2, BTRC, and ERBB2 by SM08502. Cell proliferation was inhibited in all 17 lines (avg. EC50 = 177 nM). In vivo, SM08502 was well tolerated and induced dose-dependent antitumor effects in xenografts and PDX models. Tumor growth inhibition for 25 mg/kg QD (max dose) was 83%, 56%, and 70% in SW480, HCT 116, and PDX, respectively. PD analysis showed significant inhibition ( P< .05 vs. vehicle) of TCF7, MYC, LRP5, DVL2, and BTRC expression 8 hrs post treatment. Conclusions: In preclinical CRC models, SM08502 was a potent inhibitor of Wnt pathway signaling and gene expression. It showed strong antitumor activity in human tumor models with activating Wnt pathway mutations. The safety, tolerability, and PK of SM08502 are being evaluated in an ongoing phase 1 study (NCT03355066).

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

MYC modulators in cancer: a patent review

ABSTRACTIntroduction: The important role of MYC in tumorigenesis makes it particularly important to design MYC modulators. Over the past decade, researchers have raised a number of strategies for designing MYC modulators, some of which are already in clinical trials. This paper aims to review the patents of MYC modulators.Areas covered: The important biological relevance of c-MYC and the regulation pathways related to c-MYC are briefly introduced. Base on that, the MYC modulators reported in published patents and references primarily for cancer treatment are outlined, highlighting the structures and biological activities.Expert opinion: There has been a growing awareness of finding and designing MYC modulators as novel anticancer drugs over recent years. Patents involving the discovery, synthesis, and application of MYC modulators are particularly important for further development in this field. Although finding direct MYC inhibitors or binders is challenging, MYC cannot be simply defined as an undruggable target. There is still substantial evidence proving the concept that MYC modulators can benefit to the treatment of both human hematological malignancies and solid tumors. More efforts should be taken to improve the activity and specificity of MYC modulators.

Inhibition of MYC by the SMARCB1 tumor suppressor

SMARCB1 encodes the SNF5 subunit of the SWI/SNF chromatin remodeler. SNF5 also interacts with the oncoprotein transcription factor MYC and is proposed to stimulate MYC activity. The concept that SNF5 is a coactivator for MYC, however, is at odds with its role as a tumor-suppressor, and with observations that loss of SNF5 leads to activation of MYC target genes. Here, we reexamine the relationship between MYC and SNF5 using biochemical and genome-wide approaches. We show that SNF5 inhibits the DNA-binding ability of MYC and impedes target gene recognition by MYC in cells. We further show that MYC regulation by SNF5 is separable from its role in chromatin remodeling, and that reintroduction of SNF5 into SMARCB1-null cells mimics the primary transcriptional effects of MYC inhibition. These observations reveal that SNF5 antagonizes MYC and provide a mechanism to explain how loss of SNF5 can drive malignancy.

Long path to MYC inhibition approaches clinical trials.

Omomyc, a MYC dominant-negative gene product that is used to inhibit MYC for research purposes, can penetrate cancer cells in vitro and in vivo, bringing it closer to evaluation in the clinic.

Cytochrome c Deficiency Confers Apoptosome and Mitochondrial Dysfunction in African-American Men with Prostate Cancer.

Although African-American (AA) patients with prostate cancer tend to develop greater therapeutic resistance and faster prostate cancer recurrence compared with Caucasian-American (CA) men, the molecular mechanisms of this racial prostate cancer disparity remain undefined. In this study, we provide the first comprehensive evidence that cytochrome c deficiency in AA primary tumors and cancer cells abrogates apoptosome-mediated caspase activation and contributes to mitochondrial dysfunction, thereby promoting therapeutic resistance and prostate cancer aggressiveness in AA men. In AA prostate cancer cells, decreased nuclear accumulation of nuclear respiration factor 1 (Nrf1) and its subsequent loss of binding to the cytochrome c promoter mediated cytochrome c deficiency. The activation of cellular Myc (c-Myc) and NF-κB or inhibition of AKT prevented nuclear translocation of Nrf1. Genetic and pharmacologic inhibition of c-Myc and NF-κB or activation of AKT promoted Nrf1 binding to cytochrome c promoter, cytochrome c expression, caspase activation, and cell death. The lack of p-Drp1S616 in AA prostate cancer cells contributed to defective cytochrome c release and increased resistance to apoptosis, indicating that restoration of cytochrome c alone may be insufficient to induce effective apoptosis. Cytochrome c deficiency promoted the acquisition of glycolytic phenotypes and mitochondrial dysfunction, whereas cytochrome c restoration via inhibition of c-Myc and NF-κB or activation of AKT attenuated glycolysis in AA prostate cancer cells. Inhibition of c-Myc and NF-κB enhanced the efficacy of docetaxel in tumor xenografts. Therefore, restoring cytochrome c may overcome therapeutic resistance and prostate cancer aggressiveness in AA men. Overall, this study provides the first comprehensive experimental, mechanistic, and clinical evidence for apoptosome and mitochondrial dysfunction in prostate cancer racial disparity. SIGNIFICANCE: Mechanistic insights on prostate cancer health disparity among American men provide novel approaches to restore mitochondrial function, which can address therapeutic resistance and aggressiveness in African-American men with prostate cancer.

FGF2 induces breast cancer growth through ligand-independent activation and recruitment of ERα and PRBΔ4 isoform to MYC regulatory sequences.

Progression to hormone-independent growth leading to endocrine therapy resistance occurs in a high proportion of patients with estrogen receptor alpha (ERα) and progesterone receptors (PR) positive breast cancer. We and others have previously shown that estrogen- and progestin-induced tumor growth requires ERα and PR interaction at their target genes. Here, we show that fibroblast growth factor 2 (FGF2)-induces cell proliferation and tumor growth through hormone-independent ERα and PR activation and their interaction at the MYC enhancer and proximal promoter. MYC inhibitors, antiestrogens or antiprogestins reverted FGF2-induced effects. LC-MS/MS identified 700 canonical proteins recruited to MYC regulatory sequences after FGF2 stimulation, 397 of which required active ERα (ERα-dependent). We identified ERα-dependent proteins regulating transcription that, after FGF2 treatment, were recruited to the enhancer as well as proteins involved in transcription initiation that were recruited to the proximal promoter. Also, among the ERα-dependent and independent proteins detected at both sites, PR isoforms A and B as well as the novel protein product PRBΔ4 were found. PRBΔ4 lacks the hormone-binding domain and was able to induce reporter gene expression from estrogen-regulated elements and to increase cell proliferation when cells were stimulated with FGF2 but not by progestins. Analysis of the Cancer Genome Atlas data set revealed that PRBΔ4 expression is associated with worse overall survival in luminal breast cancer patients. This discovery provides a new mechanism by which growth factor signaling can engage nonclassical hormone receptor isoforms such as PRBΔ4, which interacts with growth-factor activated ERα and PR to stimulate MYC gene expression and hence progression to endocrine resistance.

Induction of GNMT by 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranoside through proteasome-independent MYC downregulation in hepatocellular carcinoma

Glycine-N-methyl transferase (GNMT) a tumor suppressor for hepatocellular carcinoma (HCC) plays a crucial role in liver homeostasis. Its expression is downregulated in almost all the tumor tissues of HCC while the mechanism of this downregulation is not yet fully understood. Recently, we identified 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranoside (PGG) as a GNMT promoter enhancer compound in HCC. In this study, we aimed to delineate the mechanism by which PGG enhances GNMT expression and to investigate its effect on GNMT suppression in HCC. Microarray and pathway enrichment analysis revealed that MYC was a major target of PGG. PGG suppressed MYC mRNA and protein expression in Huh7 and Hep G2 cells in a dose- and time-dependent fashion. Furthermore, MYC expression was also reduced in xenograft tumors in PGG treated mice. Moreover, shRNA-mediated knocked-down or pharmacological inhibition of MYC resulted in a significant induction of GNMT promoter activity and endogenous GNMT mRNA expression in Huh7 cells. In contrast, overexpression of MYC significantly inhibited GNMT promoter activity and endogenous GNMT protein expression. In addition, antibodies against MYC effectively precipitated the human GNMT promoter in a chromatin immunoprecipitation assay. Lastly, GNMT expression was negatively correlated with MYC expression in human HCC samples. Interestingly, PGG not only inhibited MYC gene expression but also promoted MYC protein degradation through proteasome-independent pathways. This work reveals a novel anticancer mechanism of PGG via downregulation of MYC expression and establishes a therapeutic rationale for treatment of MYC overexpressing cancers using PGG. Our data also provide a novel mechanistic understanding of GNMT regulation through MYC in the pathogenesis of HCC.

The splicing factor RBM25 controls MYC activity in acute myeloid leukemia

Cancer sequencing studies have implicated regulators of pre-mRNA splicing as important disease determinants in acute myeloid leukemia (AML), but the underlying mechanisms have remained elusive. We hypothesized that “non-mutated” splicing regulators may also play a role in AML biology and therefore conducted an in vivo shRNA screen in a mouse model of CEBPA mutant AML. This has led to the identification of the splicing regulator RBM25 as a novel tumor suppressor. In multiple human leukemic cell lines, knockdown of RBM25 promotes proliferation and decreases apoptosis. Mechanistically, we show that RBM25 controls the splicing of key genes, including those encoding the apoptotic regulator BCL-X and the MYC inhibitor BIN1. This mechanism is also operative in human AML patients where low RBM25 levels are associated with high MYC activity and poor outcome. Thus, we demonstrate that RBM25 acts as a regulator of MYC activity and sensitizes cells to increased MYC levels.

Inhibition of MYC attenuates tumor cell self-renewal and promotes senescence in SMARCB1-deficient Group 2 atypical teratoid rhabdoid tumors to suppress tumor growth in vivo.

Loss of SMARCB1 is the hallmark genetic event that characterizes rhabdoid tumors in children. Rhabdoid tumors of the brain (ATRT) occur in young children and are particularly challenging with poor long-term survival. SMARCB1 is a member of the SWI/SNF chromatin remodeling complex that is responsible for determining cellular pluripotency and lineage commitment. The mechanisms by which SMARCB1 deletion results in tumorigenesis remain unclear. Recent studies demonstrate that ATRT consists of 3 genomic subgroups with a subset of poor outcome tumors expressing high BMP and MYC pathway activation. Here we show that MYC occupies distinct promoter loci in ATRT compared to embryonic stem (ES) cells. Furthermore, using human ATRT cell lines, patient-derived cell culture, ex vivo patient-derived tumor, and orthotopic xenograft models, we show that MYC inhibition is a molecular vulnerability in SMARCB1-deleted tumors and that such inhibition effectively suppresses BMP and pluripotency-associated genomic programs, attenuates tumor cell self-renewal, promotes senescence, and inhibits ATRT tumor growth in vivo. Transgenic expression of Omomyc (a bona-fide MYC dominant negative) or chemical inhibition of MYC transcriptomic programs with the BET inhibitor JQ1 phenocopy genetic depletion of MYC, effectively restricting ATRT tumor growth and opening a promising therapeutic avenue for rhabdoid tumors in children.

Dual regulation of lin28a by Myc is necessary during zebrafish retina regeneration.

Cellular reprogramming leading to induction of Muller glia-derived progenitor cells (MGPCs) with stem cell characteristics is essential for zebrafish retina regeneration. Although several regeneration-specific genes are characterized, the significance of MGPC-associated Mycb induction remains unknown. Here, we show that early expression of Mycb induces expression of genes like ascl1a, a known activator of lin28a in MGPCs. Notably, mycb is simultaneously activated by Ascl1a and repressed by Insm1a in regenerating retina. Here, we unravel a dual role of Mycb in lin28a expression, both as an activator through Ascl1a in MGPCs and a repressor in combination with Hdac1 in neighboring cells. Myc inhibition reduces the number of MGPCs and abolishes normal regeneration. Myc in collaboration with Hdac1 inhibits her4.1, an effector of Delta-Notch signaling. Further, we also show the repressive role of Delta-Notch signaling on lin28a expression in post-injured retina. Our studies reveal mechanistic understanding of Myc pathway during zebrafish retina regeneration, which could pave way for therapeutic intervention during mammalian retina regeneration.

Identification of Prognostic Biomarkers and Drugs Targeting Them in Colon Adenocarcinoma: A Bioinformatic Analysis.

Objective: To identify prognostic biomarkers and drugs that target them in colon adenocarcinoma (COAD) based on the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. Methods: The TCGA dataset was used to identify the top 50 upregulated differentially expressed genes (DEGs), and Gene Expression Omnibus profiles were used for validation. Survival analyses were conducted with the TCGA dataset using the RTCGAToolbox package in the R software environment. Drugs targeting the candidate prognostic biomarkers were searched in the DrugBank and herbal databases. Results: Among the top 50 upregulated DEGs in patients with COAD in the TCGA dataset, the Wnt signaling pathway and cytokine-cytokine receptor interactions and pathways in cancer Kyoto Encyclopedia of Genes and Genomes pathway analysis were enriched in DEGs. Tissue development and regulation of cell proliferation were the main Gene Ontology biological processes associated with upregulated DEGs. MYC and KLK6 were overexpressed in tumors validated in the TCGA, GSE41328, and GSE113513 databases (all P < .001) and were significantly associated with overall survival in patients with COAD (P = .021 and P = .047). Nadroparin and benzamidine were identified as inhibitors of MYC and KLK6 in DrugBank, and 8 herbs targeting MYC, including Da Huang (Radix Rhei Et Rhizome), Hu Zhang (Polygoni Cuspidati Rhizoma Et Radix), Huang Lian (Coptidis Rhizoma), Ban Xia (Arum Ternatum Thunb), Tu Fu Ling (Smilacis Glabrae Rhixoma), Lei Gong Teng (Tripterygii Radix), Er Cha (Catechu), and Guang Zao (Choerospondiatis Fructus), were identified. Conclusion: MYC and KLK6 may serve as candidate prognostic predictors and therapeutic targets in patients with COAD.