Transcriptional regulation and transformation by Myc proteins

Targeting processive transcription for Myc-driven circuitry in medulloblastoma

Background

Medulloblastoma is the most common malignant brain tumor of childhood. The highest-risk tumors are driven by recurrent Myc amplifications (Myc-MB) and experience poorer outcomes despite intensive multimodal therapy. The Myc transcription factor defines core regulatory circuitry for these tumors and acts to broadly amplify downstream pro-survival transcriptional programs. Therapeutic targeting of Myc directly has proven elusive, but inhibiting transcriptional cofactors may present an indirect means of drugging the oncogenic transcriptional circuitry sustaining Myc-MB.

Methods

Independent CRISPR-Cas9 screens were pooled to identify conserved dependencies in Myc-MB. We performed chromatin conformation capture (Hi-C) from primary patient Myc-MB samples to map enhancer-promoter interactions. We then treated in vitro and xenograft models with CDK9/7 inhibitors to evaluate effect on Myc-driven programs and tumor growth.

Results

Eight CRISPR-Cas9 screens performed across three independent labs identify CDK9 as a conserved dependency in Myc-MB. Myc-MB cells are susceptible to CDK9 inhibition, which is synergistic with concurrent inhibition of CDK7. Inhibition of transcriptional CDKs disrupts enhancer-promoter activity in Myc-MB and downregulates Myc-driven transcriptional programs, exerting potent anti-tumor effect.

Conclusions

Our findings identify CDK9 inhibition as a translationally promising strategy for the treatment of Myc-MB.

K ey P oints

CDK9 is an intrinsic dependency in Myc-driven medulloblastomaDual CDK9/7 inhibition disrupts Myc-driven transcriptional circuitryCDK9 inhibitors should be developed as pharmaceutical agents for Myc-MB.

I mportance of the S tudy

Medulloblastoma is the most common malignant brain tumor of childhood, and outcomes for high-risk subgroups remain unsatisfactory despite intensive multimodal therapy. In this study, we pool multiple independent CRISPR-Cas9 screens to identify transcriptional cofactors such as CDK9 as conserved dependencies in Myc-MB. Using Hi-C from primary patient samples, we map Myc enhancer-promoter interactions and show that they can be disrupted using inhibition of transcriptional CDKs. CDK9 inhibitor treatment depletes Myc-driven transcriptional programs, leading to potent anti-tumor effect in vitro and prolongation of xenograft survival in vivo . With a large number of CDK9 inhibitory compounds now in clinical development, this study highlights the opportunity for clinical translation of these for children diagnosed with Myc-MB.

Ribosome specialization by cancer-associated ribosomal protein mutations: progress made and open questions

Congenital mutations in ribosomal proteins (RPs) cause Diamond-Blackfan anaemia (DBA) syndrome. Whereas DBA patients suffer from anaemia and disease symptoms owing to a lack of cell proliferation (hypo-proliferation) early in life, they have a significantly elevated risk of developing cancer (a disease of hyper-proliferation) at a later age. The association between ribosome defects and cancer is further underscored by animal models in which heterozygous RP loss promotes tumourigenesis, as well as by a variety of somatic RP mutations that have been described in haematological and solid malignancies. As discussed in this article, we have gained deeper insight into molecular mechanisms by which RP mutations can be associated with hypo- followed by hyper-proliferation phenotypes. Factors such as oxidative stress and DNA damage, onco-ribosome specialization with hyper-translation of oncogenes and altered extra-ribosomal functions seem essential. However, many questions still remain and more research is needed to explore to what extent different cancer-associated RP mutations can structurally and functionally specialize ribosomes into onco-ribosomes, and what opportunities this can provide to develop innovative cancer therapies.This article is part of the discussion meeting issue 'Ribosome diversity and its impact on protein synthesis, development and disease'.

MAL2 and rab17 selectively redistribute invadopodia proteins to laterally-induced protrusions in hepatocellular carcinoma cells

MAL2 (myelin and lymphocyte protein 2) and rab17 have been identified as hepatocellular carcinoma tumor suppressors. However, little is known how their functions in hepatic polarized protein sorting/trafficking translate into how they function in the epithelial-to-mesenchymal transition and/or the mesenchymal-to-epithelial transition in metastases. To investigate this, we expressed MAL2 and rab17 alone or together in hepatoma-derived Clone 9 cells (that lack endogenous MAL2 and rab17). Like MAL2, we found that rab17 expression led to the formation of actin- and cholesterol-dependent protrusions that correlated to its anti-oncogenic properties. MAL2 or rab17 selectively promoted the redistribution of invadopodia proteins to the protrusion tips that correlated with decreased matrix degradation. MAL2-mediated redistribution required a putative EVH1 recognition motif whereas rab17-mediated redistribution was GTP dependent. We also determined that MAL2 and rab17 interaction was GTP dependent, but not dependent on the MAL2 EVH1 recognition motifs, and that protrusions formed by their combined expression shared features of those induced by either alone. Finally, we report that MAL2 or rab17 can redirect trafficking of newly synthesized membrane proteins from the Golgi to the induced protrusions and that the EVH1 recognition motif was required in MAL2 and that rab17-mediated trafficking was GTP dependent.

Ornithine decarboxylase and its role in cancer

Cancer is among the leading causes of death worldwide. The effectiveness of conventional chemotherapy has some drawbacks, therefore, there is an urgency to develop novel strategies to fight this disease. Ornithine decarboxylase (ODC) is the most finely tuned enzyme of the polyamine (PA) biosynthesis pathway as it is regulated at different levels: transcriptional, translational, post-translational, and by feedback inhibition. In cancer, this enzyme is overexpressed due to its regulation by the protooncogene c-Myc, thus it has been proposed as a drug target against this disease. This review describes information regarding the biochemistry and regulation of the ODC at different levels and its role in cancer. Moreover, we discuss the molecules aiming on the inhibition of the ODC activity that have been tested as therapeutic options. ODC remains as a therapeutic opportunity that needs to be more explored.

Targeting the MYCN-MDM2 pathways for cancer therapy: Are they druggable?

Targeting oncogenes and their interactive partners is an effective approach to developing novel targeted therapies for cancer and other chronic diseases. We and others have long suggested the MDM2 oncogene being an excellent target for cancer therapy, based on its p53-dependent and -independent oncogenic activities in a variety of cancers. The MYC family proteins are transcription factors that also regulate diverse biological functions. Dysregulation of MYC, such as amplification of MYCN, is associated with tumorigenesis, especially for neuroblastoma. Although the general survival rate of neuroblastoma patients has significantly improved over the past few decades, high-risk neuroblastoma still presents a poor prognosis. Therefore, innovative and more potent therapeutic strategies are needed to eradicate these aggressive neoplasms. This review focuses on the oncogenic properties of MYCN and its molecular regulation and summarizes the major therapeutic strategies being developed based on preclinical findings. We also highlight the potential benefits of targeting both the MYCN and MDM2 oncogenes, providing preclinical evidence of the efficacy and safety of this approach. In conclusion, the development of effective small molecules that inhibit both MYCN and MDM2 represents a promising new strategy for the treatment of neuroblastoma and other cancers.

GCIP and SIRT6 cooperatively suppress ITGAV gene expression by modulating c-myc transcription ability

Grap2 and CyclinD1 interacting protein (GCIP) has been suggested to function as a tumor suppressor and acts as a transcriptional regulator that negatively controls cancer cell growth, invasion, and migration. Knockdown of GCIP reportedly enhances cancer cell migration and invasion, but no previous study has examined the mechanism(s) by which GCIP suppresses migration/invasion in cancer cells. Here, we report that cDNA microarray-based expression profiling of A549 cells without and with knockdown of GCIP reveals that the expression levels of ITGAV and ICAM-1 are negatively regulated by GCIP. In vitro co-immunoprecipitation and in vivo proximity ligation assays reveal that GCIP interacts with c-Myc. Sequence analyses reveal the presence of two c-Myc regulatory motifs (E-boxes) within the ITGAV promoter. Luciferase reporter and ChIP assays indicate that GCIP represses ITGAV transcription by interacting with c-Myc on the E-box binding sites of the ITGAV promoter region. Furthermore, GCIP interacts with SIRT6 in vitro and in vivo and cooperates with SIRT6, thereby linking its activity, to negatively regulate transcription at the E-box by modulating c-Myc transcription ability. Taken together, these findings contribute to our understanding of GCIP in tumorigenesis and identify a previously unrecognized function of GCIP: It can interact with c-Myc and SIRT6 at E-box binding sites of the ITGAV promoter region. Our data collectively reveal a regulatory network involving GCIP, SIRT6, c-Myc, and ITGAV, and suggest that the SIRT6-GCIP complex negatively regulates the oncogenic function of c-Myc in cell proliferation and migration.

Targeting N-Myc in neuroblastoma with selective Aurora kinase A degraders

The N-Myc transcription factor, encoded by MYCN, is a mechanistically validated, yet challenging, target for neuroblastoma (NB) therapy development. In normal neuronal progenitors, N-Myc undergoes rapid degradation, while, in MYCN-amplified NB cells, Aurora kinase A (Aurora-A) binds to and stabilizes N-Myc, resulting in elevated protein levels. Here, we demonstrate that targeted protein degradation of Aurora-A decreases N-Myc levels. A potent Aurora-A degrader, HLB-0532259 (compound 4), was developed from an Aurora-A-binding ligand that engages the Aurora-A/N-Myc complex. HLB-0532259 promotes the degradation of Aurora-A, which elicits concomitant N-Myc degradation, with nanomolar potency and excellent selectivity. HLB-0532259 surpasses the cellular efficacy of established allosteric Aurora-A inhibitors, exhibits favorable pharmacokinetic properties, and elicits tumor reduction in a murine xenograft NB model. This study broadly delineates a strategy for targeting "undruggable" proteins that are reliant on accessory proteins for cellular stabilization.

Targeting MYCN upregulates L1CAM tumor antigen in MYCN-dysregulated neuroblastoma to increase CAR T cell efficacy

Current treatment protocols have limited success against MYCN-amplified neuroblastoma. Adoptive T cell therapy presents an innovative strategy to improve cure rates. However, L1CAM-targeting CAR T cells achieved only limited response against refractory/relapsed neuroblastoma so far. We investigated how oncogenic MYCN levels influence tumor cell response to CAR T cells, as one possible factor limiting clinical success. A MYCN-inducible neuroblastoma cell model was created. L1CAM-CAR T cell effector function was assessed (activation markers, cytokine release, tumor cytotoxicity) after coculture with the model or MYCN-amplified neuroblastoma cell lines. RNA sequencing datasets characterizing the model were compared to publicly available RNA/proteomic datasets. MYCN-directed L1CAM regulation was explored using public ChIP-sequencing datasets. Synergism between CAR T cells and the indirect MYCN inhibitor, MLN8237, was assessed in vitro using the Bliss model and in vivo in an immunocompromised mouse model. Inducing high MYCN levels in the neuroblastoma cell model reduced L1CAM expression and, consequently, L1CAM-CAR T cell effector function in vitro. Primary neuroblastomas possessing high MYCN levels expressed lower levels of both the L1CAM transcript and L1CAM tumor antigen. MLN8237 treatment restored L1CAM tumor expression and L1CAM-CAR T cell effector function. Combining MLN8237 and L1CAM-CAR T cell treatment synergistically enhanced MYCN-overexpressing tumor cytotoxicity in vitro and in vivo concomitant with severe in vivo toxicity. We identify target antigen downregulation as source of resistance against L1CAM-CAR T cells in MYCN-driven neuroblastoma cells. These data suggest that L1CAM-CAR T cell therapy combined with pharmacological MYCN inhibition may benefit patients with MYCN-amplified neuroblastoma.

Beyond small molecules: advancing MYC-targeted cancer therapies through protein engineering

Protein engineering has emerged as a powerful approach toward the development of novel therapeutics targeting the MYC/MAX/E-box network, an active driver of >70% of cancers. The MYC/MAX heterodimer regulates numerous genes in our cells by binding the Enhancer box (E-box) DNA site and activating the transcription of downstream genes. Traditional small molecules that inhibit MYC face significant limitations that include toxic effects, drug delivery challenges, and resistance. Recent advances in protein engineering offer promising alternatives by creating protein-based drugs that directly disrupt the MYC/MAX dimerization interface and/or MYC/MAX's binding to specific DNA targets. Designed DNA binding proteins like Omomyc, DuoMyc, ME47, MEF, and Mad inhibit MYC activity through specific dimerization, sequestration, and DNA-binding mechanisms. Compared to small molecules, these engineered proteins can offer superior specificity and efficacy and provide a potential pathway for overcoming the limitations of traditional cancer therapies. The success of these protein therapeutics highlights the importance of protein engineering in developing cancer treatments.

Conditional Activation of c-MYC in Distinct Catecholaminergic Cells Drives Development of Neuroblastoma or Somatostatinoma

c-MYC is an important driver of high-risk neuroblastoma. A lack of c-MYC-driven genetically engineered mouse models (GEMM) has hampered the ability to better understand mechanisms of neuroblastoma oncogenesis and to develop effective therapies. In this study, we showed that conditional c-MYC induction via Cre recombinase driven by a tyrosine hydroxylase promoter led to a preponderance of PDX1+ somatostatinoma, a type of pancreatic neuroendocrine tumor. However, c-MYC activation via an improved Cre recombinase driven by a dopamine β-hydroxylase promoter resulted in neuroblastoma development. The c-MYC murine neuroblastoma tumors recapitulated the pathologic and genetic features of human neuroblastoma and responded to anti-GD2 immunotherapy and difluoromethylornithine, an FDA-approved inhibitor targeting the MYC transcriptional target ODC1. Thus, c-MYC overexpression results in different but related tumor types depending on the targeted cell. The GEMMs represent valuable tools for testing immunotherapies and targeted therapies for these diseases. Significance: The development of c-MYC-driven genetically engineered neuroblastoma and somatostatinoma mouse models provides useful tools for understanding the tumor cell origin and investigating treatment strategies.

Transcriptomic analysis reinforces the implication of spatacsin in neuroinflammation and neurodevelopment

Hereditary spastic paraplegia (HSP) encompasses a group of rare genetic diseases primarily affecting motor neurons. Among these, spastic paraplegia type 11 (SPG11) represents a complex form of HSP caused by deleterious variants in the SPG11 gene, which encodes the spatacsin protein. Previous studies have described several potential roles for spatacsin, including its involvement in lysosome and autophagy mechanisms, neuronal and neurites development or mitochondria function. Despite these findings, the precise function of the spatacsin protein remains elusive. To elucidate its function, we conducted an extensive RNA sequencing (RNAseq) experiment and transcriptomic analysis in three distinct neural structures (cerebellum, cortex and hippocampus) and at three different ages (6 weeks, 4 months and 8 months) in both wild type and Spg11-/- mice. Our functional analysis of differentially expressed genes (DEGs) and Gene Set Enrichment Analysis (GSEA) revealed dysregulation in pathways related to inflammation, RNA metabolism and neuronal and neurite development, factors frequently implicated in neurodegenerative disorders. Notably, we also observed early deregulation in cellular pathways related to cell proliferation. Our results represent a significant step towards a better understanding of the functions of spatacsin in the cell and the underlying cellular mechanisms disrupted by its absence.

c-Myc, AKT, Hsc70, and the T-Box Transcription Factor TBX3 Form an Important Oncogenic Signaling Axis in Breast Cancer

Breast cancer is the second leading cause of death in women globally, and it remains a health burden due to poor therapy response, cancer cell drug resistance, and the debilitating side effects associated with most therapies. One approach to addressing the need to improve breast cancer therapies has been to elucidate the mechanism(s) underpinning this disease to identify key drivers that can be targeted in molecular therapies. The T-box transcription factor, TBX3, is upregulated in breast cancer, in which it contributes to important oncogenic processes, and it has been validated as a potential therapeutic target. Here, we investigated the molecular mechanisms that upregulate TBX3 in breast cancer, and we show that it involves transcriptional activation by c-Myc, post-translational modification by AKT1 and AKT3, and interaction with the molecular chaperone Hsc70. Together, the results from this study provide evidence that c-Myc, AKT, Hsc70, and TBX3 form part of an important oncogenic pathway in breast cancer and thus reveal versatile ways of interfering with the oncogenic activity of TBX3 for the treatment of this neoplasm. Implications: Targeting the c-Myc/AKT/TBX3/Hsc70 signaling axis may be an effective treatment strategy for TBX3-driven breast cancer.

Advances in the approaches used to repurpose drugs for neuroblastoma

INTRODUCTION

Neuroblastoma (NB) remains a challenging pediatric malignancy with limited treatment options, particularly for high-risk cases. Drug repurposing offers a convenient and cost-effective strategy for treating rare diseases like NB. Using existing drugs with known safety profiles accelerates the availability of new treatments, reduces development costs, and mitigates risks, offering hope for improved patient outcomes in challenging conditions.

AREAS COVERED

This review provides an overview of the advances in approaches used to repurpose drugs for NB therapy. The authors discuss strategies employed in drug repurposing, including computational and experimental methods, and rational drug design, highlighting key examples of repurposed drugs with promising clinical results. Additionally, the authors examine the challenges and opportunities associated with drug repurposing in NB and discuss future directions and potential areas for further research.

EXPERT OPINION

The fact that only one new drug has been approved in the last 30 years for the treatment of neuroblastoma plus a significant proportion of high-risk NB patients that remain uncurable, evidences the need for new fast and cost-effective alternatives. Drug repurposing may accelerate the treatment development process while reducing expenses and risks. This approach can swiftly bring effective NB therapies to market, enhancing survival rates and patient quality of life.

Chromosome 8q24 amplification associated with human hepatocellular carcinoma predicts MYC/ZEB1/MIZ1 transcriptional regulation

Genomic instability is associated with late stage carcinomas and the epithelial mesenchymal transition (EMT). Of note is chromosome 8q24 amplification that has been documented in many epithelial-derived carcinomas. On this amplified region is the potent oncogene, c-myc. Not only does MYC overexpression activate targets that promote cell proliferation, it also activates transcription factors that drive EMT, including ZEB1. Further reinforcing EMT, overexpressed MYC also represses tumor suppressors involved in promoting the epithelial phenotype, including MIZ1. We predict that as carcinomas progress, chromosome 8q24 is amplified leading to high MYC levels that leads to ZEB1 expression and MIZ1 repression driving cells through EMT. To interrogate this clinically, limited cohorts of human epithelial-derived carcinomas were examined for MYC/ZEB1/MIZ1 expression patterns across increasing carcinoma grades. Interestingly, the predicted temporal patterns were only observed in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinomas. Yet MIZ1 proved to be an excellent marker to assess carcinoma progression across types. We expanded the HCC cohort and determined that c-myc amplification was restricted to grade III/IV HCC that also exhibited increased MYC and ZEB1 nuclear expression whereas cytosolic MIZ1 expression was lost and only nuclear expression retained. These same resections were obtained from only individuals who had histories of alcohol consumption that were also diagnosed with cirrhosis, metastasis and had viral hepatitis suggesting etiology-specific mechanisms of cancer progression. Finally, analysis performed in Hep3B cells determined that alterations in MYC expression promoted the predicted changes in ZEB1 and MIZ1 expression and/or distributions and in markers for EMT further suggesting a relationship among these three transcription factors in HCC and their correlation to driving EMT.

Circulating non-coding RNA biomarkers of endocrine tumours

Circulating non-coding RNA (ncRNA) molecules are being investigated as biomarkers of malignancy, prognosis and follow-up in several neoplasms, including endocrine tumours of the pituitary, parathyroid, pancreas and adrenal glands. Most of these tumours are classified as neuroendocrine neoplasms (comprised of neuroendocrine tumours and neuroendocrine carcinomas) and include tumours of variable aggressivity. We consider them together here in this Review owing to similarities in their clinical presentation, pathomechanism and genetic background. No preoperative biomarkers of malignancy are available for several forms of these endocrine tumours. Moreover, biomarkers are also needed for the follow-up of tumour progression (especially in hormonally inactive tumours), prognosis and treatment efficacy monitoring. Circulating blood-borne ncRNAs show promising utility as biomarkers. These ncRNAs, including microRNAs, long non-coding RNAs and circular RNAs, are involved in several aspects of gene expression regulation, and their stability and tissue-specific expression could make them ideal biomarkers. However, no circulating ncRNA biomarkers have yet been introduced into routine clinical practice, which is mostly owing to methodological and standardization problems. In this Review, following a brief synopsis of these endocrine tumours and the biology of ncRNAs, the major research findings, pathomechanisms and methodological questions are discussed along with an outlook for future studies.

HSPA12A promotes c-Myc lactylation-mediated proliferation of tubular epithelial cells to facilitate renal functional recovery from kidney ischemia/reperfusion injury

Proliferation of renal tubular epithelial cells (TEC) is essential for restoring tubular integrity and thereby to support renal functional recovery from kidney ischemia/reperfusion (KI/R) injury. Activation of transcriptional factor c-Myc promotes TEC proliferation following KI/R; however, the mechanism regarding c-Myc activation in TEC is incompletely known. Heat shock protein A12A (HSPA12A) is an atypic member of HSP70 family. In this study, we found that KI/R decreased HSPA12A expression in mouse kidneys and TEC, while ablation of HSPA12A in mice impaired TEC proliferation and renal functional recovery following KI/R. Gain-of-functional studies demonstrated that HSPA12A promoted TEC proliferation upon hypoxia/reoxygenation (H/R) through directly interacting with c-Myc and enhancing its nuclear localization to upregulate expression of its target genes related to TEC proliferation. Notably, c-Myc was lactylated in TEC after H/R, and this lactylation was enhanced by HSPA12A overexpression. Importantly, inhibition of c-Myc lactylation attenuated the HSPA12A-induced increases of c-Myc nuclear localization, proliferation-related gene expression, and TEC proliferation. Further experiments revealed that HSPA12A promoted c-Myc lactylation via increasing the glycolysis-derived lactate generation in a Hif1α-dependent manner. The results unraveled a role of HSPA12A in promoting TEC proliferation and facilitating renal recovery following KI/R, and this role of HSPA12A was achieved through increasing lactylation-mediated c-Myc activation. Therefore, targeting HSPA12A in TEC might be a viable strategy to promote renal functional recovery from KI/R injury in patients.

Dysfunction of Calcyphosine-Like gene impairs retinal angiogenesis through the MYC axis and is associated with familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a severe genetic disorder characterized by incomplete vascularization of the peripheral retina and associated symptoms that can lead to vision loss. However, the underlying genetic causes of approximately 50% of FEVR cases remain unknown. Here, we report two heterozygous variants in calcyphosine-like gene (CAPSL) that is associated with FEVR. Both variants exhibited compromised CAPSL protein expression. Vascular endothelial cell (EC)-specific inactivation of Capsl resulted in delayed radial/vertical vascular progression, compromised endothelial proliferation/migration, recapitulating the human FEVR phenotypes. CAPSL-depleted human retinal microvascular endothelial cells (HRECs) exhibited impaired tube formation, decreased cell proliferation, disrupted cell polarity establishment, and filopodia/lamellipodia formation, as well as disrupted collective cell migration. Transcriptomic and proteomic profiling revealed that CAPSL abolition inhibited the MYC signaling axis, in which the expression of core MYC targeted genes were profoundly decreased. Furthermore, a combined analysis of CAPSL-depleted HRECs and c-MYC-depleted human umbilical vein endothelial cells uncovered similar transcription patterns. Collectively, this study reports a novel FEVR-associated candidate gene, CAPSL, which provides valuable information for genetic counseling of FEVR. This study also reveals that compromised CAPSL function may cause FEVR through MYC axis, shedding light on the potential involvement of MYC signaling in the pathogenesis of FEVR.

Metastatic extraneural glioblastoma diagnosed with molecular testing

Glioblastoma, the most common malignant brain tumor in adults, is associated with a median overall survival duration of less than 2 years. Extraneural metastases occur in less than 1% of all patients with glioblastoma. The mechanism of extraneural metastasis is unclear. We present a case of extensive extraneural, extraosseous, epidural, and soft-tissue metastasis of glioblastoma. The diagnosis of metastatic glioblastoma was made only after next-generation sequencing (NGS) of the metastatic paraspinal lesions was completed. The CDK4, pTERT, PTEN, and TP53 molecular alterations seen in the initial intracranial glioblastoma were found in the paraspinal tumor, along with the addition of MYC, which is implicated in angiogenesis and epidermal-to-mesenchymal transition. Immunohistochemical stains showed that neoplastic cells were negative for GFAP. In conclusion, this case raises awareness about the role of NGS in the diagnosis of extraneural glioblastoma. This diagnosis was not possible with histology alone and only became evident after molecular profiling of the metastatic lesions and its comparison to the original tumor.

Mechanistic Insights into the c-MYC G-Quadruplex and Berberine Binding inside an Aqueous Two-Phase System Mimicking Biomolecular Condensates

We investigated the binding between the c-MYC G-quadruplex (GQ) and berberine chloride (BCl) in an aqueous two-phase system (ATPS) with 12.3 wt % polyethylene glycol and 5.6 wt % dextran, mimicking the highly crowded intracellular biomolecular condensates formed via liquid-liquid phase separation. We found that in the ATPS, complex formation is significantly altered, leading to an increase in affinity and a change in the stoichiometry of the complex with respect to neat buffer conditions. Thermodynamic studies reveal that binding becomes more thermodynamically favorable in the ATPS due to entropic effects, as the strong excluded volume effect inside ATPS droplets reduces the entropic penalty associated with binding. Finally, the binding affinity of BCl for the c-MYC GQ is higher than those for other DNA structures, indicating potential specific interactions. Overall, these findings will be helpful in the design of potential drugs targeting the c-MYC GQ structures in cancer-related biocondensates.

Using microRNAs Networks to Understand Pancreatic Cancer-A Literature Review

Pancreatic cancer is a severe disease, challenging to diagnose and treat, and thereby characterized by a poor prognosis and a high mortality rate. Pancreatic ductal adenocarcinoma (PDAC) represents approximately 90% of pancreatic cancer cases, while other cases include neuroendocrine carcinoma. Despite the growing knowledge of the pathophysiology of this cancer, the mortality rate caused by it has not been effectively reduced. Recently, microRNAs have aroused great interest among scientists and clinicians, as they are negative regulators of gene expression, which participate in many processes, including those related to the development of pancreatic cancer. The aim of this review is to show how microRNAs (miRNAs) affect key signaling pathways and related cellular processes in pancreatic cancer development, progression, diagnosis and treatment. We included the results of in vitro studies, animal model of pancreatic cancer and those performed on blood, saliva and tumor tissue isolated from patients suffering from PDAC. Our investigation identified numerous dysregulated miRNAs involved in KRAS, JAK/STAT, PI3/AKT, Wnt/β-catenin and TGF-β signaling pathways participating in cell cycle control, proliferation, differentiation, apoptosis and metastasis. Moreover, some miRNAs (miRNA-23a, miRNA-24, miRNA-29c, miRNA-216a) seem to be engaged in a crosstalk between signaling pathways. Evidence concerning the utility of microRNAs in the diagnosis and therapy of this cancer is poor. Therefore, despite growing knowledge of the involvement of miRNAs in several processes associated with pancreatic cancer, we are beginning to recognize and understand their role and usefulness in clinical practice.

Exploring Myc puzzle: Insights into cancer, stem cell biology, and PPI networks

"The grand orchestrator," "Universal Amplifier," "double-edged sword," and "Undruggable" are just some of the Myc oncogene so-called names. It has been around 40 years since the discovery of the Myc, and it remains in the mainstream of cancer treatment drugs. Myc is part of basic helix-loop-helix leucine zipper (bHLH-LZ) superfamily proteins, and its dysregulation can be seen in many malignant human tumors. It dysregulates critical pathways in cells that are connected to each other, such as proliferation, growth, cell cycle, and cell adhesion, impacts miRNAs action, intercellular metabolism, DNA replication, differentiation, microenvironment regulation, angiogenesis, and metastasis. Myc, surprisingly, is used in stem cell research too. Its family includes three members, MYC, MYCN, and MYCL, and each dysfunction was observed in different cancer types. This review aims to introduce Myc and its function in the body. Besides, Myc deregulatory mechanisms in cancer cells, their intricate aspects will be discussed. We will look at promising drugs and Myc-based therapies. Finally, Myc and its role in stemness, Myc pathways based on PPI network analysis, and future insights will be explained.

Analysis of the Skin and Brain Transcriptome of Normally Pigmented and Pseudo-Albino Southern Flounder (Paralichthys lethostigma) Juveniles to Study the Molecular Mechanisms of Hypopigmentation and Its Implications for Species Survival in the Natural Environment

Southern flounder skin pigmentation is a critical phenotypic characteristic for this species' survival in the natural environment. Normal pigmentation allows rapid changes of color for concealment to capture prey and UV light protection. In contrast, highly visible hypopigmented pseudo-albinos exhibit a compromised immune system and are vulnerable to predation, sensitive to UV exposure, and likely have poor survival in the wild. Skin and brain tissue samples from normally pigmented and hypopigmented individuals were analyzed with next-generation RNA sequencing. A total of 1,589,613 transcripts were used to identify 952,825 genes to assemble a de novo transcriptome, with 99.43% of genes mapped to the assembly. Differential gene expression and gene enrichment analysis of contrasting tissues and phenotypes revealed that pseudo-albino individuals appeared more susceptible to environmental stress, UV light exposure, hypoxia, and osmotic stress. The pseudo-albinos' restricted immune response showed upregulated genes linked to cancer development, signaling and response, skin tissue formation, regeneration, and healing. The data indicate that a modified skin collagen structure likely affects melanocyte differentiation and distribution, generating the pseudo-albino phenotype. In addition, the comparison of the brain transcriptome revealed changes in myelination and melanocyte stem cell activity, which may indicate modified brain function, reduced melanocyte migration, and impaired vision.

Suppression of interferon α and γ response by Huwe1-mediated Miz1 degradation promotes SARS-CoV-2 replication

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been demonstrated to limit the host interferon response; however, the underlying mechanism remains unclear. Here, we found that SARS-CoV-2 infection upregulated the E3 ubiquitin ligase Huwe1, which in turn facilitated the degradation of the transcription factor Miz1. The degradation of Miz1 hampered interferon alpha and gamma responses, consequently fostering viral replication and impeding viral clearance. Conversely, silencing or inhibiting Huwe1 enhanced the interferon responses, effectively curbing viral replication. Consistently, overexpressing Miz1 augmented the interferon responses and limited viral replication, whereas silencing Miz1 had the opposite effect. Targeting Huwe1 or overexpressing Miz1 elicited transcriptomic alterations characterized by enriched functions associated with bolstered antiviral response and diminished virus replication. Further study revealed Miz1 exerted epigenetic control over the transcription of specific interferon signaling molecules, which acted as common upstream regulators responsible for the observed transcriptomic changes following Huwe1 or Miz1 targeting. These findings underscore the critical role of the Huwe1-Miz1 axis in governing the host antiviral response, with its dysregulation contributing to the impaired interferon response observed during COVID-19.

In silico identification of a novel Cdc2-like kinase 2 (CLK2) inhibitor in triple negative breast cancer

Dysregulation of RNA splicing processes is intricately linked to tumorigenesis in various cancers, especially breast cancer. Cdc2-like kinase 2 (CLK2), an oncogenic RNA-splicing kinase pivotal in breast cancer, plays a significant role, particularly in the context of triple-negative breast cancer (TNBC), a subtype marked by substantial medical challenges due to its low survival rates. In this study, we employed a structure-based virtual screening (SBVS) method to identify potential CLK2 inhibitors with novel chemical structures for treating TNBC. Compound 670551 emerged as a novel CLK2 inhibitor with a 50% inhibitory concentration (IC50) value of 619.7 nM. Importantly, Compound 670551 exhibited high selectivity for CLK2 over other protein kinases. Functionally, this compound significantly reduced the survival and proliferation of TNBC cells. Results from a cell-based assay demonstrated that this inhibitor led to a decrease in RNA splicing proteins, such as SRSF4 and SRSF6, resulting in cell apoptosis. In summary, we identified a novel CLK2 inhibitor as a promising potential treatment for TNBC therapy.

Conditional c-MYC activation in catecholaminergic cells drives distinct neuroendocrine tumors: neuroblastoma vs somatostatinoma

The MYC proto-oncogenes (c-MYC, MYCN , MYCL ) are among the most deregulated oncogenic drivers in human malignancies including high-risk neuroblastoma, 50% of which are MYCN -amplified. Genetically engineered mouse models (GEMMs) based on the MYCN transgene have greatly expanded the understanding of neuroblastoma biology and are powerful tools for testing new therapies. However, a lack of c-MYC-driven GEMMs has hampered the ability to better understand mechanisms of neuroblastoma oncogenesis and therapy development given that c-MYC is also an important driver of many high-risk neuroblastomas. In this study, we report two transgenic murine neuroendocrine models driven by conditional c-MYC induction in tyrosine hydroxylase (Th) and dopamine β-hydroxylase (Dbh)-expressing cells. c-MYC induction in Th-expressing cells leads to a preponderance of Pdx1 + somatostatinomas, a type of pancreatic neuroendocrine tumor (PNET), resembling human somatostatinoma with highly expressed gene signatures of δ cells and potassium channels. In contrast, c-MYC induction in Dbh-expressing cells leads to onset of neuroblastomas, showing a better transforming capacity than MYCN in a comparable C57BL/6 genetic background. The c-MYC murine neuroblastoma tumors recapitulate the pathologic and genetic features of human neuroblastoma, express GD2, and respond to anti-GD2 immunotherapy. This model also responds to DFMO, an FDA-approved inhibitor targeting ODC1, which is a known MYC transcriptional target. Thus, establishing c-MYC-overexpressing GEMMs resulted in different but related tumor types depending on the targeted cell and provide useful tools for testing immunotherapies and targeted therapies for these diseases.

MYC the oncogene from hell: Novel opportunities for cancer therapy

Cancer comprises a heterogeneous disease, characterized by diverse features such as constitutive expression of oncogenes and/or downregulation of tumor suppressor genes. MYC constitutes a master transcriptional regulator, involved in many cellular functions and is aberrantly expressed in more than 70 % of human cancers. The Myc protein belongs to a family of transcription factors whose structural pattern is referred to as basic helix-loop-helix-leucine zipper. Myc binds to its partner, a smaller protein called Max, forming an Myc:Max heterodimeric complex that interacts with specific DNA recognition sequences (E-boxes) and regulates the expression of downstream target genes. Myc protein plays a fundamental role for the life of a cell, as it is involved in many physiological functions such as proliferation, growth and development since it controls the expression of a very large percentage of genes (∼15 %). However, despite the strict control of MYC expression in normal cells, MYC is often deregulated in cancer, exhibiting a key role in stimulating oncogenic process affecting features such as aberrant proliferation, differentiation, angiogenesis, genomic instability and oncogenic transformation. In this review we aim to meticulously describe the fundamental role of MYC in tumorigenesis and highlight its importance as an anticancer drug target. We focus mainly on the different categories of novel small molecules that act as inhibitors of Myc function in diverse ways hence offering great opportunities for an efficient cancer therapy. This knowledge will provide significant information for the development of novel Myc inhibitors and assist to the design of treatments that would effectively act against Myc-dependent cancers.

Targeting MYC at the intersection between cancer metabolism and oncoimmunology

MYC activation is a known hallmark of cancer as it governs the gene targets involved in various facets of cancer progression. Of interest, MYC governs oncometabolism through the interactions with its partners and cofactors, as well as cancer immunity via its gene targets. Recent investigations have taken interest in characterizing these interactions through multi-Omic approaches, to better understand the vastness of the MYC network. Of the several gene targets of MYC involved in either oncometabolism or oncoimmunology, few of them overlap in function. Prominent interactions have been observed with MYC and HIF-1α, in promoting glucose and glutamine metabolism and activation of antigen presentation on regulatory T cells, and its subsequent metabolic reprogramming. This review explores existing knowledge of the role of MYC in oncometabolism and oncoimmunology. It also unravels how MYC governs transcription and influences cellular metabolism to facilitate the induction of pro- or anti-tumoral immunity. Moreover, considering the significant roles MYC holds in cancer development, the present study discusses effective direct or indirect therapeutic strategies to combat MYC-driven cancer progression.

DOT1L stimulates MYC/Mondo transcription factor activity by promoting its degradation cycle on chromatin

The proto-oncogene c-MYC is a key representative of the MYC transcription factor network regulating growth and metabolism. MML-1 (Myc- and Mondo-like) is its homolog in C. elegans. The functional and molecular cooperation between c-MYC and H3 lysine 79 methyltransferase DOT1L was demonstrated in several human cancer types, and we have earlier discovered the connection between C. elegans MML-1 and DOT-1.1. Here, we demonstrate the critical role of DOT1L/DOT-1.1 in regulating c-MYC/MML-1 target genes genome-wide by ensuring the removal of "spent" transcription factors from chromatin by the nuclear proteasome. Moreover, we uncover a previously unrecognized proteolytic activity of DOT1L, which may facilitate c-MYC turnover. This new mechanism of c-MYC regulation by DOT1L may lead to the development of new approaches for cancer treatment.

Hypoxia-inducible factor in cancer: from pathway regulation to therapeutic opportunity

Cancer remains one of the most formidable challenges in modern medicine, due to its complex and dynamic nature, which demands innovative therapeutic approaches. One major challenge to cancer treatment is the tumour microenvironment and in particular tumour hypoxia (low oxygen levels), which contributes to tumour progression and immune evasion. At the cellular level, this is primarily governed by hypoxia-inducible factor (HIF). HIF is a transcription factor that orchestrates cellular responses to low oxygen levels, driving angiogenesis, metabolic adaptation and immune regulation. HIF's dysregulation is frequently observed in various cancer types and correlates with increased aggressiveness, metastasis, resistance to therapy and poor patient prognosis. Consequently, understanding the cellular mechanisms underlying HIF activation and its downstream effects has become crucial to developing targeted cancer therapies for improving cancer patient outcomes and represents a key step towards precision medicine. Recent advancements in drug development have led to the emergence of HIF inhibitors, which aim to disrupt HIF-driven processes in cancer providing therapeutic benefit. Here, we provide a review of the molecular mechanisms through which HIF promotes tumour growth and resistance, emphasising the potential clinical benefits of HIF-targeted therapies. This review will discuss the challenges and opportunities associated with translating HIF inhibition into clinical practice, including ongoing clinical trials and future directions in the development of HIF-based cancer treatments.

Intrinsically Disordered Regions in the Transcription Factor MYC:MAX Modulate DNA Binding via Intramolecular Interactions

The basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factor (TF) MYC is in large part an intrinsically disordered oncoprotein. In complex with its obligate heterodimerization partner MAX, MYC preferentially binds E-Box DNA sequences (CANNTG). At promoters containing these sequence motifs, MYC controls fundamental cellular processes such as cell cycle progression, metabolism, and apoptosis. A vast network of proteins in turn regulates MYC function via intermolecular interactions. In this work, we establish another layer of MYC regulation by intramolecular interactions. We used nuclear magnetic resonance (NMR) spectroscopy to identify and map multiple binding sites for the C-terminal MYC:MAX DNA-binding domain (DBD) on the intrinsically disordered regions (IDRs) in the MYC N-terminus. We find that these binding events in trans are driven by electrostatic attraction, that they have distinct affinities, and that they are competitive with DNA binding. Thereby, we observe the strongest effects for the N-terminal MYC box 0 (Mb0), a conserved motif involved in MYC transactivation and target gene induction. We prepared recombinant full-length MYC:MAX complex and demonstrate that the interactions identified in this work are also relevant in cis, i.e., as intramolecular interactions. These findings are supported by surface plasmon resonance (SPR) experiments, which revealed that intramolecular IDR:DBD interactions in MYC decelerate the association of MYC:MAX complexes to DNA. Our work offers new insights into how bHLH-LZ TFs are regulated by intramolecular interactions, which open up new possibilities for drug discovery.

USP43 stabilizes c-Myc to promote glycolysis and metastasis in bladder cancer

A hallmark of tumor cells, including bladder cancer (BLCA) cells, is metabolic reprogramming toward aerobic glycolysis (Warburg effect). The classical oncogene MYC, which is crucial in regulating glycolysis, is amplified and activated in BLCA. However, direct targeting of the c-Myc oncoprotein, which regulates glycolytic metabolism, presents great challenges and necessitates the discovery of a more clarified regulatory mechanism to develop selective targeted therapy. In this study, a siRNA library targeting deubiquitinases identified a candidate enzyme named USP43, which may regulate glycolytic metabolism and c-Myc transcriptional activity. Further investigation using functional assays and molecular studies revealed a USP43/c-Myc positive feedback loop that contributes to the progression of BLCA. Moreover, USP43 stabilizes c-Myc by deubiquitinating c-Myc at K148 and K289 primarily through deubiquitinase activity. Additionally, upregulation of USP43 protein in BLCA increased the chance of interaction with c-Myc and interfered with FBXW7 access and degradation of c-Myc. These findings suggest that USP43 is a potential therapeutic target for indirectly targeting glycolytic metabolism and the c-Myc oncoprotein consequently enhancing the efficacy of bladder cancer treatment.

Mechanism-centric regulatory network identifies NME2 and MYC programs as markers of Enzalutamide resistance in CRPC

Heterogeneous response to Enzalutamide, a second-generation androgen receptor signaling inhibitor, is a central problem in castration-resistant prostate cancer (CRPC) management. Genome-wide systems investigation of mechanisms that govern Enzalutamide resistance promise to elucidate markers of heterogeneous treatment response and salvage therapies for CRPC patients. Focusing on the de novo role of MYC as a marker of Enzalutamide resistance, here we reconstruct a CRPC-specific mechanism-centric regulatory network, connecting molecular pathways with their upstream transcriptional regulatory programs. Mining this network with signatures of Enzalutamide response identifies NME2 as an upstream regulatory partner of MYC in CRPC and demonstrates that NME2-MYC increased activities can predict patients at risk of resistance to Enzalutamide, independent of co-variates. Furthermore, our experimental investigations demonstrate that targeting MYC and its partner NME2 is beneficial in Enzalutamide-resistant conditions and could provide an effective strategy for patients at risk of Enzalutamide resistance and/or for patients who failed Enzalutamide treatment.

Ecdysone and gene expressions for chromatin remodeling, histone modification, and Broad Complex in relation to pupal commitment in Bombyx mori

In the present study, we tried to clarify when and how pupal commitment (PT) better to use PC occurs and what is involved in the PT of Bombyx mori. To clarify this, we examined the responsiveness of a wing disc to ecdysone, referring to metamorphosis-related BR-C, development-related Myc and Wnt, and chromatin remodeling-related genes at around the predicted PT stage of the Bombyx wing disc. Wing disc responsiveness to juvenile hormone (JH) and ecdysone was examined using Methoprene and 20-hydroxyecdysone (20E) in vitro. The body weight of B. mori increased after the last larval ecdysis, peaked at Day 5 of the fifth larval instar (D5L5), and then decreased. The responsiveness of the wing disc to JH decreased after the last larval ecdysis up to D3L5. Bmbr-c (the Broad Complex of B. mori) showed enhanced expression in D4L5 wing discs with 20E treatment. Some chromatin remodeler and histone modifier genes (Bmsnr1, Bmutx, and Bmtip60) showed upregulation after being cultured with 20E in D4L5 wing discs. A low concentration of 20E is suggested to induce responsiveness to 20E in D4L5 wing discs. Bmbr-c, Bmsnr1, Bmutx, and Bmtip60 were upregulated after being cultured with a low concentration of 20E in D4L5 wing discs. The expression of Bmmyc and Bmwnt1 did not show a change after being cultured with or without 20E in D4L5 wing discs, while enhanced expression was observed with 20E in D5L5 wing discs. From the present results, we concluded that PT of the wing disc of B. mori occurred beginning on D4L5 with the secretion of low concentrations of ecdysteroids. Bmsnr1, Bmutx, Bmtip60, and BR-C are also involved.

BRD4 as a potential target for human papillomaviruses associated cancer

Around 99% of cervical cancer and 5%-10% of human cancer are associated with human papillomaviruses (HPV). Notably, the life-cycle of HPV begins by low-level infection of the basal cells of the stratified epithelium, where the viral genomes are replicated and passed on to the daughter proliferating basal cells. The production of new viral particles remains restricted to eventually differentiated cells. HPVs support their persistent infectious cycle by hijacking pivotal pathways and cellular processes. Bromodomain-containing protein 4 (BRD4) is one of the essential cellular factors involved in multiple stages of viral transcription and replication. In this review, we demonstrate the role of BRD4 in the multiple stages of HPV infectious cycle. Also, we provide an overview of the intense research about the cellular functions of BRD4, the mechanism of action of bromodomain and extra terminal inhibitors, and how it could lead to the development of antiviral/anticancer therapies.

Targeting c-MYC: a potential non-hormonal therapeutic approach for endometriosis treatment

Endometriosis is a benign gynecological disease in which eutopic endometrial tissue composed of glands and stroma grow within the pelvic cavity. The disease affects females of reproductive age and is characterized by pelvic pain, infertility and reduced quality of life. The majority of pharmacologic treatment modalities for endometriosis focus on suppression of estradiol production and/or action; an approach associated with adverse side effects. c-MYC is elevated in eutopic endometrium and endometriotic lesion tissue in patients with endometriosis and the disease shares many similar pathological characteristics with that of endometrial carcinoma. While targeting of c-MYC with Omomyc has recently gained substantial interest in the field of cancer research, there has been no recent attempt to evaluate the potential utility in targeting c-MYC for endometriosis treatment. The following perspective article compares the similarities between endometriosis and endometrial cancer and presents preliminary data suggesting that targeting c-MYC with Omomyc reduces endometriotic cell proliferation and viability in vitro. Future application of targeting c-MYC in endometriosis treatment and potential pros and cons are then discussed.

G-quadruplexes in cancer-related gene promoters: from identification to therapeutic targeting

INTRODUCTION

Guanine-rich DNA sequences can fold into four-stranded noncanonical secondary structures called G-quadruplexes (G4s) which are widely distributed in functional regions of the human genome, such as telomeres and gene promoter regions. Compelling evidence suggests their involvement in key genome functions such as gene expression and genome stability. Notably, the abundance of G4-forming sequences near transcription start sites suggests their potential involvement in regulating oncogenes.

AREAS COVERED

This review provides an overview of current knowledge on G4s in human oncogene promoters. The most representative G4-binding ligands have also been documented. The objective of this work is to present a comprehensive overview of the most promising targets for the development of novel and highly specific anticancer drugs capable of selectively impacting the expression of individual or a limited number of genes.

EXPERT OPINION

Modulation of G4 formation by specific ligands has been proposed as a powerful new tool to treat cancer through the control of oncogene expression. Actually, most of G4-binding small molecules seem to simultaneously target a range of gene promoter G4s, potentially influencing several critical driver genes in cancer, thus producing significant therapeutic benefits.

Computational completion of the Aurora interaction region of N-Myc in the Aurora a kinase complex

Inhibiting protein-protein interactions of the Myc family is a viable pharmacological strategy for modulation of the levels of Myc oncoproteins in cancer. Aurora A kinase (AurA) and N-Myc interaction is one of the most attractive targets of this strategy because formation of this complex blocks proteasomal degradation of N-Myc in neuroblastoma. Two crystallization studies have captured this complex (PDB IDs: 5g1x, 7ztl), partially resolving the AurA interaction region (AIR) of N-Myc. Prompted by the missing N-Myc fragment in these crystal structures, we modeled the complete structure between AurA and N-Myc, and comprehensively analyzed how the incomplete and complete N-Myc behave in complex by molecular dynamics simulations. Molecular dynamics simulations of the incomplete PDB complex (5g1x) repeatedly showed partial dissociation of the short N-Myc fragment (61-89) from the kinase. The missing N-Myc (19-60) fragment was modeled utilizing the N-terminal lobe of AurA as the protein-protein interaction surface, wherein TPX2, a well-known partner of AurA, also binds. Binding free energy calculations along with flexibility analysis confirmed that the complete AIR of N-Myc stabilizes the complex, accentuating the N-terminal lobe of AurA as a binding site for the missing N-Myc fragment (19-60). We further generated additional models consisting of only the missing N-Myc (19-60), and the fused form of TPX2 (7-43) and N-Myc (61-89). These partners also formed more stable interactions with the N-terminal lobe of AurA than did the incomplete N-Myc fragment (61-89) in the 5g1x complex. Altogether, this study provides structural insights into the involvement of the N-terminus of the AIR of N-Myc and the N-terminal lobe of AurA in formation of a stable complex, reflecting its potential for effective targeting of N-Myc.

MYC function and regulation in physiological perspective

MYC, a key member of the Myc-proto-oncogene family, is a universal transcription amplifier that regulates almost every physiological process in a cell including cell cycle, proliferation, metabolism, differentiation, and apoptosis. MYC interacts with several cofactors, chromatin modifiers, and regulators to direct gene expression. MYC levels are tightly regulated, and deregulation of MYC has been associated with numerous diseases including cancer. Understanding the comprehensive biology of MYC under physiological conditions is an utmost necessity to demark biological functions of MYC from its pathological functions. Here we review the recent advances in biological mechanisms, functions, and regulation of MYC. We also emphasize the role of MYC as a global transcription amplifier.

Transcriptome analysis of divergent residual feed intake phenotypes in the M. longissimus thoracis et lumborum of Wannan Yellow rabbits

Introduction: Feed efficiency is an important economic trait in rabbit meat production. The identification of molecular mechanisms and candidate genes for feed efficiency may improve the economic and environmental benefits of the rabbit meat industry. As an alternative to the conventional feed conversion ratio, residual feed intake (RFI) can be used as an accurate indicator of feed efficiency. Methods: RNA sequencing was used to identify the differentially expressed genes (DEGs) in the M. longissimus thoracis et lumborum of eight Wannan Yellow rabbits with excessively high or low RFIs (HRFI or LRFI, respectively). Thereafter, Gene Ontology (GO) analysis, enrichment using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, gene set enrichment analysis (GSEA), and protein-protein interaction (PPI) network analysis was conducted. Results: In total, 445 DEGs were identified in the M. longissimus thoracis et lumborum of rabbits with high and low RFIs. The significantly enriched GO terms identified in these two groups were primarily involved in energy and mitochondrial metabolism and oxidation-reduction processes. KEGG analysis identified 11 significantly enriched pathways, including oxidative phosphorylation, PI3K-Akt signaling, and extracellular matrix-receptor interaction pathways. According to GSEA, the expressions of genes and pathways related to mitochondrial function were upregulated in HRFI rabbits, whereas genes with upregulated expressions in LRFI rabbits were related to immune response and energy metabolism. Additionally, PPI network analysis revealed five potential candidate genetic markers. Conclusion: Comparative analysis of the M. longissimus thoracis et lumborum transcriptomes in HRFI and LRFI rabbits revealed FOS, MYC, PRKACB, ITGA2, and FN1 as potential candidate genes that affect feed efficiency in rabbits. In addition, key signaling pathways involved in oxidative phosphorylation and PI3K-Akt and ECM-receptor interaction signaling impact rabbit feed efficiency. These findings will aid in breeding programs to improve feed efficiency and optimize RFI selection of rabbits for meat production.

Overexpression of deubiquitinase (usp 36) in oral squamous cell carcinoma

Aim

Oral cancer is one of the top three types of cancer and is of significant public health importance in India. A common post-translational modification in cells is ubiquitination/deubiquitination, and its dysregulation is closely associated with the development of cancer. Studies on the role of ubiquitination in oral squamous cell carcinoma (OSCC) are lacking. Increased expression of usp36 has been observed in various types of cancer, and this study aimed to check the gene expression of usp36 in OSCC patients. In this study, we analyzed the expression of ubiquitin-specific proteases (USPs) 36 in OSCC.

Materials and Methods

A total of 15 OSCC patients at different stages of tumor differentiation and age- and sex-matched controls were recruited for the study. The patients were categorized based on their differentiation patterns. RNA was extracted from the tissues, and usp36 gene expression was checked in these samples using a quantitative real-time PCR technique.

Results

Our study showed increased expression of usp36 gene in OSCC patients. The usp36 mRNA was 231.8 ± 137.94 folds higher in well-differentiated squamous cell carcinoma patients, 38.18 ± 3.77 folds higher in moderately differentiated squamous cell carcinoma patients, and 25.49 ± 7.30 folds higher in poorly differentiated squamous cell carcinoma patients compared to control tissues.

Conclusion

Our study reports, for the first time, an increased gene expression of usp36 in OSCC tissues.

Role of HNF4alpha-cMyc interaction in liver regeneration and recovery after acetaminophen-induced acute liver injury

BACKGROUND AND AIMS

Overdose of acetaminophen (APAP) is the major cause of acute liver failure in the western world. We report a novel signaling interaction between hepatocyte nuclear factor 4 alpha (HNF4α) cMyc and nuclear factor erythroid 2-related factor 2 (Nrf2) during liver injury and regeneration after APAP overdose.

APPROACH AND RESULTS

APAP-induced liver injury and regeneration were studied in male C57BL/6J (WT) mice, hepatocyte-specific HNF4α knockout mice (HNF4α-KO), and HNF4α-cMyc double knockout mice (DKO). C57BL/6J mice treated with 300 mg/kg maintained nuclear HNF4α expression and exhibited liver regeneration, resulting in recovery. However, treatment with 600-mg/kg APAP, where liver regeneration was inhibited and recovery was delayed, showed a rapid decline in HNF4α expression. HNF4α-KO mice developed significantly higher liver injury due to delayed glutathione recovery after APAP overdose. HNF4α-KO mice also exhibited significant induction of cMyc, and the deletion of cMyc in HNF4α-KO mice (DKO mice) reduced the APAP-induced liver injury. The DKO mice had significantly faster glutathione replenishment due to rapid induction in Gclc and Gclm genes. Coimmunoprecipitation and ChIP analyses revealed that HNF4α interacts with Nrf2 and affects its DNA binding. Furthermore, DKO mice showed significantly faster initiation of cell proliferation resulting in rapid liver regeneration and recovery.

CONCLUSIONS

These data show that HNF4α interacts with Nrf2 and promotes glutathione replenishment aiding in recovery from APAP-induced liver injury, a process inhibited by cMyc. These studies indicate that maintaining the HNF4α function is critical for regeneration and recovery after APAP overdose.

Unraveling MYC's Role in Orchestrating Tumor Intrinsic and Tumor Microenvironment Interactions Driving Tumorigenesis and Drug Resistance

The transcription factor MYC plays a pivotal role in regulating various cellular processes and has been implicated in tumorigenesis across multiple cancer types. MYC has emerged as a master regulator governing tumor intrinsic and tumor microenvironment interactions, supporting tumor progression and driving drug resistance. This review paper aims to provide an overview and discussion of the intricate mechanisms through which MYC influences tumorigenesis and therapeutic resistance in cancer. We delve into the signaling pathways and molecular networks orchestrated by MYC in the context of tumor intrinsic characteristics, such as proliferation, replication stress and DNA repair. Furthermore, we explore the impact of MYC on the tumor microenvironment, including immune evasion, angiogenesis and cancer-associated fibroblast remodeling. Understanding MYC's multifaceted role in driving drug resistance and tumor progression is crucial for developing targeted therapies and combination treatments that may effectively combat this devastating disease. Through an analysis of the current literature, this review's goal is to shed light on the complexities of MYC-driven oncogenesis and its potential as a promising therapeutic target.

Role of c-Myc in lung cancer: Progress, challenges, and prospects

Lung cancer remains the leading cause of cancer-related deaths worldwide. Despite the recent advances in cancer therapies, the 5-year survival of non-small cell lung cancer (NSCLC) patients hovers around 20%. Inherent and acquired resistance to therapies (including radiation, chemotherapies, targeted drugs, and combination therapies) has become a significant obstacle in the successful treatment of NSCLC. c-Myc, one of the critical oncoproteins, has been shown to be heavily associated with the malignant cancer phenotype, including rapid proliferation, metastasis, and chemoresistance across multiple cancer types. The c-Myc proto-oncogene is amplified in small cell lung cancers (SCLCs) and overexpressed in over 50% of NSCLCs. c-Myc is known to actively regulate the transcription of cancer stemness genes that are recognized as major contributors to tumor progression and therapeutic resistance; thus, targeting c-Myc either directly or indirectly in mitigation of the cancer stemness phenotype becomes a promising approach for development of a new strategy against drug resistant lung cancers. This review will summarize what is currently known about the mechanisms underlying c-Myc regulation of cancer stemness and its involvement in drug resistance and offer an overview on the current progress and future prospects in therapeutically targeting c-Myc in both SCLC and NSCLC.

The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics

Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.

Induced pluripotent stem cells for cardiovascular therapeutics: Progress and perspectives

The discovery of methods for reprogramming adult somatic cells into induced pluripotent stem cells (iPSCs) opens up prospects of developing personalized cell-based therapy options for a variety of human diseases as well as disease modeling and new drug discovery. Like embryonic stem cells, iPSCs can give rise to various cell types of the human body and are amenable to genetic correction. This allows usage of iPSCs in the development of modern therapies for many virtually incurable human diseases. The review summarizes progress in iPSC research in the context of application in the cardiovascular field including modeling cardiovascular disease, drug study, tissue engineering, and perspectives for personalized cardiovascular medicine.

Practical Use of Immortalized Cells in Medicine: Current Advances and Future Perspectives

In modern science, immortalized cells are not only a convenient tool in fundamental research, but they are also increasingly used in practical medicine. This happens due to their advantages compared to the primary cells, such as the possibility to produce larger amounts of cells and to use them for longer periods of time, the convenience of genetic modification, the absence of donor-to-donor variability when comparing the results of different experiments, etc. On the other hand, immortalization comes with drawbacks: possibilities of malignant transformation and/or major phenotype change due to genetic modification itself or upon long-term cultivation appear. At first glance, such issues are huge hurdles in the way of immortalized cells translation into medicine. However, there are certain ways to overcome such barriers that we describe in this review. We determined four major areas of usage of immortalized cells for practical medicinal purposes, and each has its own means to negate the drawbacks associated with immortalization. Moreover, here we describe specific fields of application of immortalized cells in which these problems are of much lesser concern, for example, in some cases where the possibility of malignant growth is not there at all. In general, we can conclude that immortalized cells have their niches in certain areas of practical medicine where they can successfully compete with other therapeutic approaches, and more preclinical and clinical trials with them should be expected.

PPARγ agonist inhibits c-Myc-mediated colorectal cancer tumor immune escape

As a master transcription factor, c-Myc plays an important role in promoting tumor immune escape. In addition, PPARγ (peroxisome proliferator-activated receptor γ) regulates cell metabolism, inflammation, and tumor progression, while the effect of PPARγ on c-Myc-mediated tumor immune escape is still unclear. Here we found that cells treated with PPARγ agonist pioglitazone (PIOG) reduced c-Myc protein expression in a PPARγ-dependent manner. qPCR analysis showed that PIOG had no significant effect on c-Myc gene levels. Further analysis showed that PIOG decreased c-Myc protein half-life. Moreover, PIOG increased the binding of c-Myc to PPARγ, and induced c-Myc ubiquitination and degradation. Importantly, c-Myc increased PD-L1 and CD47 immune checkpoint protein expression and promoted tumor immune escape, while PIOG inhibited this event. These findings suggest that PPARγ agonist inhibited c-Myc-mediated tumor immune escape by inducing its ubiquitination and degradation.

Super-enhancer-driven MLX mediates redox balance maintenance via SLC7A11 in osteosarcoma

Osteosarcoma (OS) is a common type of bone tumor for which there has been limited therapeutic progress over the past three decades. The prevalence of transcriptional addiction in cancer cells emphasizes the biological significance and clinical relevance of super-enhancers. In this study, we found that Max-like protein X (MLX), a member of the Myc-MLX network, is driven by super-enhancers. Upregulation of MLX predicts a poor prognosis in osteosarcoma. Knockdown of MLX impairs growth and metastasis of osteosarcoma in vivo and in vitro. Transcriptomic sequencing has revealed that MLX is involved in various metabolic pathways (e.g., lipid metabolism) and can induce metabolic reprogramming. Furthermore, knockdown of MLX results in disturbed transport and storage of ferrous iron, leading to an increase in the level of cellular ferrous iron and subsequent induction of ferroptosis. Mechanistically, MLX regulates the glutamate/cystine antiporter SLC7A11 to promote extracellular cysteine uptake required for the biosynthesis of the essential antioxidant GSH, thereby detoxifying reactive oxygen species (ROS) and maintaining the redox balance of osteosarcoma cells. Importantly, sulfasalazine, an FDA-approved anti-inflammatory drug, can inhibit SLC7A11, disrupt redox balance, and induce massive ferroptosis, leading to impaired tumor growth in vivo. Taken together, this study reveals a novel mechanism in which super-enhancer-driven MLX positively regulates SLC7A11 to meet the alleviated demand for cystine and maintain the redox balance, highlighting the feasibility and clinical promise of targeting SLC7A11 in osteosarcoma.

MYC overrides HIF-1α to regulate proliferating primary cell metabolism in hypoxia

Hypoxia requires metabolic adaptations to sustain energetically demanding cellular activities. While the metabolic consequences of hypoxia have been studied extensively in cancer cell models, comparatively little is known about how primary cell metabolism responds to hypoxia. Thus, we developed metabolic flux models for human lung fibroblast and pulmonary artery smooth muscle cells proliferating in hypoxia. Unexpectedly, we found that hypoxia decreased glycolysis despite activation of hypoxia-inducible factor 1α (HIF-1α) and increased glycolytic enzyme expression. While HIF-1α activation in normoxia by prolyl hydroxylase (PHD) inhibition did increase glycolysis, hypoxia blocked this effect. Multi-omic profiling revealed distinct molecular responses to hypoxia and PHD inhibition, and suggested a critical role for MYC in modulating HIF-1α responses to hypoxia. Consistent with this hypothesis, MYC knockdown in hypoxia increased glycolysis and MYC over-expression in normoxia decreased glycolysis stimulated by PHD inhibition. These data suggest that MYC signaling in hypoxia uncouples an increase in HIF-dependent glycolytic gene transcription from glycolytic flux.

Divergence in cell cycle progression is associated with shifted phenology in a multivoltine moth: the European corn borer, Ostrinia nubilalis

Evolutionary change in diapause timing can be an adaptive response to changing seasonality, and even result in ecological speciation. However, the molecular and cellular mechanisms regulating shifts in diapause timing remain poorly understood. One of the hallmarks of diapause is a massive slowdown in the cell cycle of target organs such as the brain and primordial imaginal structures, and resumption of cell cycle proliferation is an indication of diapause termination and resumption of development. Characterizing cell cycle parameters between lineages differing in diapause life history timing may help identify molecular mechanisms associated with alterations of diapause timing. We tested the extent to which progression of the cell cycle differs across diapause between two genetically distinct European corn borer strains that differ in their seasonal diapause timing. We show the cell cycle slows down during larval diapause with a significant decrease in the proportion of cells in S phase. Brain-subesophageal complex cells slow primarily in G0/G1 phase whereas most wing disc cells are in G2 phase. Diapausing larvae of the earlier emerging, bivoltine E-strain (BE) suppressed cell cycle progression less than the later emerging, univoltine Z-strain (UZ) individuals, with a greater proportion of cells in S phase across both tissues during diapause. Additionally, resumption of cell cycle proliferation occurred earlier in the BE strain than in the UZ strain after exposure to diapause-terminating conditions. We propose that regulation of cell cycle progression rates ultimately drives differences in larval diapause termination, and adult emergence timing, between early- and late-emerging European corn borer strains.