The MYC oncogene is a global regulator of the immune response

Porcine epidemic diarrhea virus infection blocks cell cycle and induces apoptosis in pig intestinal epithelial cells

Porcine epidemic diarrhea virus (PEDV) is responsible for the acute infectious swine disease porcine epidemic diarrhea (PED). PED causes damage to the intestine, including villus atrophy and shedding, leading to serious economic losses to the pig industry worldwide. We carried out an in vitro study to investigate cell apoptosis and the cell cycle in a PEDV-infected host using transcriptomic shotgun sequencing (RNA-Seq) to study gene responses to PEDV infection. Results revealed that the PEDV infection reduced proliferation activity, blocked the cell cycle at S-phase and induced apoptosis in IPEC-J2 cells. The expression of gene levels related to ribosome proteins and oxidative phosphorylation were significantly up-regulated post-PEDV infection. Although the significantly down-regulated on PI3K/Akt signaling pathway post-PEDV infection, the regulator-related genes of mTOR signaling pathway exerted significantly up-regulated or down-regulated in IPEC-J2 cells. These results indicated that ribosome proteins and oxidative phosphorylation process were widely involved in the pathological changes and regulation of host cells caused by PEDV infection, and PI3K/AKT and mTOR signaling pathways played a vital role in antiviral regulation in IPEC-J2 cells. These data might provide new insights into the specific pathogenesis of PEDV infection and pave the way for the development of effective therapeutic strategies.

Insights about MYC and Apoptosis in B-Lymphomagenesis: An Update from Murine Models

The balance between cell survival and cell death represents an essential part of human tissue homeostasis, while altered apoptosis contributes to several pathologies and can affect the treatment efficacy. Impaired apoptosis is one of the main cancer hallmarks and some types of lymphomas harbor mutations that directly affect key regulators of cell death (such as BCL-2 family members). The development of novel techniques in the field of immunology and new animal models has greatly accelerated our understanding of oncogenic mechanisms in MYC-associated lymphomas. Mouse models are a powerful tool to reveal multiple genes implicated in the genesis of lymphoma and are extensively used to clarify the molecular mechanism of lymphoma, validating the gene function. Key features of MYC-induced apoptosis will be discussed here along with more recent studies on MYC direct and indirect interactors, including their cooperative action in lymphomagenesis. We review our current knowledge about the role of MYC-induced apoptosis in B-cell malignancies, discussing the transcriptional regulation network of MYC and regulatory feedback action of miRs during MYC-driven lymphomagenesis. More importantly, the finding of new modulators of apoptosis now enabling researchers to translate the discoveries that have been made in the laboratory into clinical practice to positively impact human health.

The core SWI/SNF catalytic subunit Brg1 regulates nephron progenitor cell proliferation and differentiation

Chromatin-remodeling complexes play critical roles in establishing gene expression patterns in response to developmental signals. How these epigenetic regulators determine the fate of progenitor cells during development of specific organs is not well understood. We found that genetic deletion of Brg1 (Smarca4), the core enzymatic protein in SWI/SNF, in nephron progenitor cells leads to severe renal hypoplasia. Nephron progenitor cells were depleted in Six2-Cre, Brg1^flx/flx mice due to reduced cell proliferation. This defect in self-renewal, together with impaired differentiation resulted in a profound nephron deficit in Brg1 mutant kidneys. Sall1, a transcription factor that is required for expansion and maintenance of nephron progenitors, associates with SWI/SNF. Brg1 and Sall1 bind promoters of many progenitor cell genes and regulate expression of key targets that promote their proliferation.

Analysis of DNA methylation patterns in the tumor immune microenvironment of metastatic melanoma

The presence of immune cells in the tumor microenvironment has been associated with response to immunotherapies across several cancer types, including melanoma. Despite its therapeutic relevance, characterization of the melanoma immune microenvironments remains insufficiently explored. To distinguish the immune microenvironment in a cohort of 180 metastatic melanoma clinical specimens, we developed a method using promoter CpG methylation of immune cell type-specific genes extracted from genome-wide methylation arrays. Unsupervised clustering identified three immune methylation clusters with varying levels of immune CpG methylation that are related to patient survival. Matching protein and gene expression data further corroborated the identified epigenetic characterization. Exploration of the possible immune exclusion mechanisms at play revealed likely dependency on MITF protein level and PTEN loss-of-function events for melanomas unresponsive to immunotherapies (immune-low). To understand whether melanoma tumors resemble other solid tumors in terms of immune methylation characteristics, we explored 15 different solid tumor cohorts from TCGA. Low-dimensional projection based on immune cell type-specific methylation revealed grouping of the solid tumors in line with melanoma immune methylation clusters rather than tumor types. Association of survival outcome with immune cell type-specific methylation differed across tumor and cell types. However, in melanomas immune cell type-specific methylation was associated with inferior patient survival. Exploration of the immune methylation patterns in a pan-cancer context suggested that specific immune microenvironments might occur across the cancer spectrum. Together, our findings underscore the existence of diverse immune microenvironments, which may be informative for future immunotherapeutic applications.

Deep and Prolonged Response to Aurora A Kinase Inhibitor and Subsequently to Nivolumab in MYCL1-Driven Small-Cell Lung Cancer: Case Report and Literature Review

Small-cell lung carcinoma (SCLC) is one of the most aggressive solid tumors, and the prognosis has not improved significantly in 25 years. Despite a recent understanding of the genomic aberrations seen in SCLC, these insights have not led to any breakthroughs in treatment. We present a patient with SCLC harboring a novel MYCL1 fusion protein who experienced a prolonged disease course due to the use of Aurora A kinase inhibitor and subsequently nivolumab. MYC family genes are master regulators of several cellular pathways including proliferation, differentiation, and apoptosis and recently have been shown to be involved in tumor immune evasion. Large studies have shown that a significant proportion of patients with SCLC have amplification or overexpression of MYC family genes. Preclinical data have exposed vulnerability of MYC-driven tumors to Aurora kinase inhibitors, bromodomain and extraterminal domain inhibitors, and recently to immune checkpoint blockers. Further studies using these agents with selective enrolling of patients with MYC-altered tumors are warranted to exploit these vulnerabilities.

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

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

A detailed smoking history and determination of MYC status predict response to checkpoint inhibitors in advanced non-small cell lung cancer

Background

Although many studies have determined that PD-L1 expression by immunohistochemistry can be somewhat predictive of a response to checkpoint inhibitor the impact of specific genomic changes and smoking history in the context of PD-L1 expression is limited. This single-center study examined clinical and genomic factors beyond STK11 and EGFR in patients with advanced non-small cell lung cancer (NSCLC) to determine which patients benefit from therapy with immune checkpoint inhibitors (ICIs).

Methods

Clinical and genomic features of patients with NSCLC treated with immunotherapy were compiled into a database. Genomic information collected included gene mutations via next generation sequencing, tumor mutation burden (TMB), and PD-L1 tumor proportional scores.

Results

A total of 131 patients with advanced NSCLC treated with ICIs were examined. Race was not associated with response. A positive response to immunotherapy was associated with smoke year increase (P=0.042). KRAS mutation and MYC amplification were associated with a positive response to immunotherapy while EGFR, RB1, and NF1 mutations were associated with a lack of response. KRAS mutation (P=0.007) and high TMB (P=0.070) were positively associated with smoking history. EGFR mutation was negatively associated with smoking history (P=0.002) . In multivariate analysis controlling for age and smoking history, MYC amplification continued to be the only predictive genomic marker with a trend toward response to therapy (P=0.092) beyond the smoking history.

Conclusions

Among the clinical and genomic factors examined in this study, smoking status is the most predictive of response to ICIs. Only MYC amplification continued to predict a trend toward response to immunotherapy when controlling for smoking history. Other genomic predictors such as EGFR and KRAS simply reflect their association with smoking. Detailed smoking history and MYC amplification alone can predict response to ICI.

Construction of the gene regulatory network identifies MYC as a transcriptional regulator of SWI/SNF complex

Precise positioning of nucleosomes at the gene regulatory elements mediated by the SWI/SNF family of remodelling complex is important for the transcriptional regulation of genes. A wide set of genes are either positively or negatively regulated by SWI/SNF. In higher eukaryotes, around thirty genes were found to code for SWI/SNF subunits. The construction of a gene regulatory network of SWI/SNF subunits identifies MYC as a common regulator for many of the SWI/SNF subunit genes. A meta-analysis study was conducted to investigate the MYC dependent regulation of SWI/SNF remodelling complex. Subunit information and the promoter sequences of the subunit genes were used to find the canonical E-box motif and its variants. Detailed analysis of mouse and human ChIP-Seq at the SWI/SNF subunit loci indicates the presence of MYC binding peaks overlapping with E-boxes. The co-expression correlation and the differential expression analysis of wt vs. MYC perturbed MEFs indicate the MYC dependent regulation of some of the SWI/SNF subunits. The extension of the analysis was done on MYC proficient and MYC deficient embryonic fibroblast cell lines, TGR1 and HO15, and in one of the MYC amplified cancer types, Medulloblastoma. A transcriptional regulatory feedback loop between MYC and SWI/SNF could be a major factor contributing to the aggressiveness of MYC dependent cancers.

WNT Signaling in Tumors: The Way to Evade Drugs and Immunity

WNT/β-catenin signaling is involved in many physiological processes. Its implication in embryonic development, cell migration, and polarization has been shown. Nevertheless, alterations in this signaling have also been related with pathological events such as sustaining and proliferating the cancer stem cell (CSC) subset present in the tumor bulk. Related with this, WNT signaling has been associated with the maintenance, expansion, and epithelial-mesenchymal transition of stem cells, and furthermore with two distinctive features of this tumor population: therapeutic resistance (MDR, multidrug resistance) and immune escape. These mechanisms are developed and maintained by WNT activation through the transcriptional control of the genes involved in such processes. This review focuses on the description of the best known WNT pathways and the molecules involved in them. Special attention is given to the WNT cascade proteins deregulated in tumors, which have a decisive role in tumor survival. Some of these proteins function as extrusion pumps that, in the course of chemotherapy, expel the drugs from the cells; others help the tumoral cells hide from the immune effector mechanisms. Among the WNT targets involved in drug resistance, the drug extrusion pump MDR-1 (P-GP, ABCB1) and the cell adhesion molecules from the CD44 family are highlighted. The chemokine CCL4 and the immune checkpoint proteins CD47 and PD-L1 are included in the list of WNT target molecules with a role in immunity escape. This pathway should be a main target in cancer therapy as WNT signaling activation is essential for tumor progression and survival, even in the presence of the anti-tumoral immune response and/or antineoplastic drugs. The appropriate design and combination of anti-tumoral strategies, based on the modulation of WNT mediators and/or protein targets, could negatively affect the growth of tumoral cells, improving the efficacy of these types of therapies.

Small-Molecule MYC Inhibitors Suppress Tumor Growth and Enhance Immunotherapy

Small molecules that directly target MYC and are also well tolerated in vivo will provide invaluable chemical probes and potential anti-cancer therapeutic agents. We developed a series of small-molecule MYC inhibitors that engage MYC inside cells, disrupt MYC/MAX dimers, and impair MYC-driven gene expression. The compounds enhance MYC phosphorylation on threonine-58, consequently increasing proteasome-mediated MYC degradation. The initial lead, MYC inhibitor 361 (MYCi361), suppressed in vivo tumor growth in mice, increased tumor immune cell infiltration, upregulated PD-L1 on tumors, and sensitized tumors to anti-PD1 immunotherapy. However, 361 demonstrated a narrow therapeutic index. An improved analog, MYCi975 showed better tolerability. These findings suggest the potential of small-molecule MYC inhibitors as chemical probes and possible anti-cancer therapeutic agents.

CD5+MYC+ predicts worse prognosis in diffuse large B-cell lymphoma

The dual expression of CD5 and MYC protein (DECM) on B-lymphocytes may arise at a specific stage of de novo diffuse large B-cell lymphoma (DLBCL). This study retrospectively reviewed 210 patients with de novo DLBCL at the Affiliated Hospital of Jiangnan University between 2006 and 2017. DECM was significantly correlated with a worse prognosis than that in either the CD5⁺ or MYC⁺ or CD5^-MYC^- patients. Furthermore, patients with DECM showed a similar outcome to MYC⁺BCL2⁺ lymphoma patients who have extremely poor survival rates. Multivariate analysis demonstrated that DECM was a significant independent predictor for overall survival (P < .0001) and progression-free survival (P < .0001) in DLBCL. DLBCL patients with DECM showed significantly inferior clinical outcomes compared to the CD5⁺, MYC⁺ or CD5^-MYC^- patients. Combinational therapeutic modalities might be a candidate approach to improve the prognosis of these patients.

Combining the wisdoms of traditional medicine with cutting-edge science and technology at the forefront of medical sciences

BACKGROUND

A central topic is to bring traditional medicine to a new horizon by integrating the latest advances in genomic, metabolomic, and system biological approaches, in order to re-examine the wisdom and knowledge of traditional Chinese medicine (TCM) and other traditional medicines.

PURPOSE

A new consortium has been formed at a conference of the Harvard Medical School, Boston, on October 29-30, 2018. The main goal was to build a collaborative platform for the scientific investigation of traditional medicine with cutting edge sciences and technologies at the forefront of biomedicine.

RESULTS

Traditional medicines are largely experience-based, but the scientific basis is largely non-satisfactory. Therefore, the transformation from experience-based to evidence-based medicine would be an important step forward. The consortium covers three main fields: TCM diagnostics, acupuncture and TCM pharmacology. Diseases occur because of regulatory imbalances of holistic physiological display and genetic information/expression related to systems biology and energy consumption/release (e.g. cold and hot) within body. As organs are interconnected by meridians, affecting the meridians by acupuncture and medicinal herbs restores healthy organ function and body balance. There are two concepts in herbal medicine: The traditional way is based on complex herbal mixtures. The second concept is related to Western pharmacological drug development including the isolation of bioactive phytochemicals, which are subjected to preclinical and clinical investigations.

CONCLUSION

Development of collaborative scientific project to integrate the best of both worlds - Western and Eastern medicine into a "One World Integrative Medicine" for the sake of patients worldwide.

High Incidence and Clinical Significance of MYC Rearrangements in Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) and primary cutaneous follicle center lymphoma (PCFCL) are cutaneous B-cell lymphomas (CBCL) with different clinical characteristics and behavior. PCDLBCL-LT is the most aggressive CBCL with a relatively poor prognosis. In nodal diffuse large B-cell lymphoma (DLBCL), rearrangements of the MYC gene, especially in combination with a second hit in BCL2 and/or BCL6, and double protein expression of MYC and BCL2 (DE) are adverse prognostic factors. As the clinical significance of these factors in CBCL is largely unknown, we studied the frequency and prognostic value of MYC rearrangements and DE in a cohort of 44 patients with PCDLBCL-LT and 17 patients with PCFCL. Compared with nodal DLBCL (9% to 14%), the PCDLBCL-LT patients had a high incidence of MYC rearrangements (32%), but only 2 patients (4%) had a second hit, both with BCL6. PCDLBCL-LT patients with a MYC rearrangement showed an inferior disease-specific survival (Log-rank, P=0.036) and disease-free survival (Log-rank, P=0.028), but no significant adverse effect on overall survival (Log-rank, P=0.157) at 5 years compared with patients without a MYC rearrangement. DE, present in 65% of the PCDLBCL-LT patients, was not associated with reduced survival. In the PCFCL group, MYC rearrangements and DE were not detected. In conclusion, this study identifies a high incidence of MYC rearrangements in PCDLBCL-LT compared to nodal DLBCL and further shows that a MYC rearrangement is an inferior prognostic marker in these patients. Therefore, our data suggest that it is useful to perform MYC-FISH in all newly diagnosed PCDLBCL-LT patients.

The MYC Oncogene Cooperates with Sterol-Regulated Element-Binding Protein to Regulate Lipogenesis Essential for Neoplastic Growth

Lipid metabolism is frequently perturbed in cancers, but the underlying mechanism is unclear. We present comprehensive evidence that oncogene MYC, in collaboration with transcription factor sterol-regulated element-binding protein (SREBP1), regulates lipogenesis to promote tumorigenesis. We used human and mouse tumor-derived cell lines, tumor xenografts, and four conditional transgenic mouse models of MYC-induced tumors to show that MYC regulates lipogenesis genes, enzymes, and metabolites. We found that MYC induces SREBP1, and they collaborate to activate fatty acid (FA) synthesis and drive FA chain elongation from glucose and glutamine. Further, by employing desorption electrospray ionization mass spectrometry imaging (DESI-MSI), we observed in vivo lipidomic changes upon MYC induction across different cancers, for example, a global increase in glycerophosphoglycerols. After inhibition of FA synthesis, tumorigenesis was blocked, and tumors regressed in both xenograft and primary transgenic mouse models, revealing the vulnerability of MYC-induced tumors to the inhibition of lipogenesis.

Deciphering GRINA/Lifeguard1: Nuclear Location, Ca2+ Homeostasis and Vesicle Transport

The Glutamate Receptor Ionotropic NMDA-Associated Protein 1 (GRINA) belongs to the Lifeguard family and is involved in calcium homeostasis, which governs key processes, such as cell survival or the release of neurotransmitters. GRINA is mainly associated with membranes of the endoplasmic reticulum, Golgi, endosome, and the cell surface, but its presence in the nucleus has not been explained yet. Here we dissect, with the help of different software tools, the potential roles of GRINA in the cell and how they may be altered in diseases, such as schizophrenia or celiac disease. We describe for the first time that the cytoplasmic N-terminal half of GRINA (which spans a Proline-rich domain) contains a potential DNA-binding sequence, in addition to cleavage target sites and probable PY-nuclear localization sequences, that may enable it to be released from the rest of the protein and enter the nucleus under suitable conditions, where it could participate in the transcription, alternative splicing, and mRNA export of a subset of genes likely involved in lipid and sterol synthesis, ribosome biogenesis, or cell cycle progression. To support these findings, we include additional evidence based on an exhaustive review of the literature and our preliminary data of the protein–protein interaction network of GRINA.

Metformin mediates induction of miR-708 to inhibit self-renewal and chemoresistance of breast cancer stem cells through targeting CD47

Breast cancer stem cells (BCSCs) have been considered responsible for cancer progression, recurrence, metastasis and drug resistance. However, the mechanisms by which cells acquire self-renewal and chemoresistance properties are remaining largely unclear. Herein, we evaluated the role of miR-708 and metformin in BCSCs, and found that the expression of miR-708 is significantly down-regulated in BCSCs and tumour tissues, and correlates with chemotherapy response and prognosis. Moreover, miR-708 markedly inhibits sphere formation, CD44⁺ /CD24^- ratio, and tumour initiation and increases chemosensitivity of BCSCs. Mechanistically, miR-708 directly binds to cluster of differentiation 47 (CD47), and regulates tumour-associated macrophage-mediated phagocytosis. On the other hand, CD47 is essential for self-renewal, tumour initiation and chemoresistance of BCSCs, and correlates with the prognosis of breast cancer patients. In addition, the anti-type II diabetes drug metformin are found to be involved in the miR-708/CD47 signalling pathway. Therefore, our study demonstrated that miR-708 plays an important tumour suppressor role in BCSCs self-renewal and chemoresistance, and the miR-708/CD47 regulatory axis may represent a novel therapeutic mechanism of metformin in BCSCs.

Functional and Mechanistic Interrogation of BET Bromodomain Degraders for the Treatment of Metastatic Castration-resistant Prostate Cancer

PURPOSE

The bromodomain and extraterminal (BET)-containing proteins (BRD2/3/4) are essential epigenetic coregulators for prostate cancer growth. BRD inhibitors have shown promise for treatment of metastatic castration-resistant prostate cancer (mCRPC), and have been shown to function even in the context of resistance to next-generation AR-targeted therapies such as enzalutamide and abiraterone. Their clinical translation, however, has been limited by off-target effects, toxicity, and rapid resistance.

EXPERIMENTAL DESIGN

We have developed a series of molecules that target BET bromodomain proteins through their proteasomal degradation, improving efficacy and specificity of standard inhibitors. We tested their efficacy by utilizing prostate cancer cell lines and patient-derived xenografts, as well as several techniques including RNA-sequencing, mass spectroscopic proteomics, and lipidomics.

RESULTS

BET degraders function in vitro and in vivo to suppress prostate cancer growth. These drugs preferentially affect AR-positive prostate cancer cells (22Rv1, LNCaP, VCaP) over AR-negative cells (PC3 and DU145), and proteomic and genomic mechanistic studies confirm disruption of oncogenic AR and MYC signaling at lower concentrations than BET inhibitors. We also identified increases in polyunsaturated fatty acids (PUFA) and thioredoxin-interacting protein (TXNIP) as potential pharmacodynamics biomarkers for targeting BET proteins.

CONCLUSIONS

Compounds inducing the pharmacologic degradation of BET proteins effectively target the major oncogenic drivers of prostate cancer, and ultimately present a potential advance in the treatment of mCRPC. In particular, our compound dBET-3, is most suited for further clinical development.

Abnormal Expression of c-Myc Oncogene in NK Cells in Patients with Cancer

Natural killer (NK) cells have received a lot of attention in recent years for the roles they play in immunity and particularly in antitumor immune responses. Although defects in NK cell functions are recognized as important mechanisms for immune evasion of malignant cells, molecular pathways regulating NK cell dysfunction and exhaustion in cancer are largely unknown. Here we tested whether the c-myc proto-oncogene, known to promote cell proliferation, growth, differentiation, and apoptosis by regulating the expression of numerous target genes, may be involved in the mechanism of NK cell abnormalities in patients with lung and gastric cancer. Analysis of c-myc mRNA and protein expression in peripheral blood NK cells, mitogen-activated protein kinase (MAPK) activity, cell cycle, and cell longevity revealed a significantly decreased expression of c-myc mRNA and protein and mitotic arrest of NK cells in different phases of cell cycle. In addition, a significant decrease of NK cell death was also detected. These data allow the suggestion that defects of NK cell-mediated tumor surveillance may be associated with disturbed c-myc expression in NK cells in cancer patients. A better understanding of the mechanisms of NK cell dysfunction in cancer will help in the NK cell-mediated therapeutic eradication of primary and metastatic cancer cells and prolong patient survival.

Lentiviral vector-mediated IL-9 overexpression stimulates cell proliferation by targeting c-myc and cyclin D1 in colitis-associated cancer

Colorectal cancer caused by inflammatory bowel disease is referred as colitis-associated cancer (CAC). The mechanism underling CAC is not fully understood. In the present study, the role of interleukin-9 (IL-9) in CAC was examined. The current study included 12 colorectal tissue specimens and matched adjacent tissues from CAC. The expression of IL-9 protein was examined using immunohistochemical staining. The expression of IL-9 in cancer tissues was markedly higher compared with that in adjacent tissues. Furthermore, IL-9 gene overexpression lentiviral vectors were constructed to overexpress IL-9 in RKO and Caco-2 cell lines. The role of IL-9 in cell proliferation was investigated using a Cell Counting Kit-8 assay, and MYC proto-oncogene bHLH transcription factor (c-Myc) and cyclinD1 expression levels were detected by reverse transcription-quantitative polymerase chain reaction. Notably, IL-9 overexpression promoted the proliferation of colonic epithelial cells by upregulating of the expression of c-Myc and cyclinD1. In conclusion, the present results suggested that IL-9 may exhibit an essential role in the pathogenesis of CAC, and IL-9 promotes the proliferation of colonic epithelial RKO and Caco2 cells, partially via the upregulation of c-Myc and cyclinD1 expression.