Inhibition Of C-myc Expression Research Articles

Androgen receptor monomers and dimers regulate opposing biological processes in prostate cancer cells.

Most prostate cancers express the androgen receptor (AR), and tumor growth and progression are facilitated by exceptionally low levels of systemic or intratumorally produced androgens. Thus, absolute inhibition of the androgen signaling axis remains the goal of current therapeutic approaches to treat prostate cancer (PCa). Paradoxically, high dose androgens also exhibit considerable efficacy as a treatment modality in patients with late-stage metastatic PCa. Here we show that low levels of androgens, functioning through an AR monomer, facilitate a non-genomic activation of the mTOR signaling pathway to drive proliferation. Conversely, high dose androgens facilitate the formation of AR dimers/oligomers to suppress c-MYC expression, inhibit proliferation and drive a transcriptional program associated with a differentiated phenotype. These findings highlight the inherent liabilities in current approaches used to inhibit AR action in PCa and are instructive as to strategies that can be used to develop new therapeutics for this disease and other androgenopathies.

Anti-Leukemic Effects of Small Molecule Inhibitor of c-Myc (10058-F4) on Chronic Myeloid Leukemia Cells.

As one of the main molecules in BCR-ABL signaling, c-Myc acts as a pivotal key in disease progression and disruption of long-term remission in patients with CML. To clarify the effects of c-Myc inhibition in CML, we examined the anti-tumor property of a well-known small molecule inhibitor of c-Myc 10058-F4 on K562 cell line. This experimental study was conducted in K562 cell line for evaluation of cytotoxic activity of 10058-F4 using Trypan blue and MTT assays. Flow cytometry and Quantitative RT-PCR analysis were also conducted to determine its mechanism of action. Additionally, Annexin/PI staining was performed for apoptosis assessment. The results of Trypan blue and MTT assay demonstrated that inhibition of c-Myc, as shown by suppression of c-Myc expression and its associated genes PP2A, CIP2A, and hTERT, could decrease viability and metabolic activity of K562 cells, respectively. Moreover, a robust elevation in cell population in G1-phase coupled with up-regulation of p21 and p27 expression shows that 10058-F4 could hamper cell proliferation, at least partly, through induction of G1 arrest. Accordingly, we found that 10058-F4 induced apoptosis via increasing Bax and Bad; In contrast, no significant alterations were observed NF-KB pathway-targeted anti-apoptotic genes in the mRNA levels. Notably, disruption of the NF-κB pathway with bortezomib as a common proteasome inhibitor sensitized K562 cells to the cytotoxic effect of 10058-F4, substantiating the fact that the NF-κB axis functions probably attenuate the K562 cells sensitivity to c-Myc inhibition. It can be concluded from the results of this study that inhibition of c-Myc induces anti-neoplastic effects on CML-derived K562 cells as well as increases the efficacy of imatinib. For further insight into the safety and effectiveness of 10058-F4 in CML, in vivo studies will be required.

ULK1-dependent phosphorylation of PKM2 antagonizes O-GlcNAcylation and regulates the Warburg effect in breast cancer.

Pyruvate kinase M2 (PKM2) is a central metabolic enzyme driving the Warburg effect in tumor growth. Previous investigations have demonstrated that PKM2 is subject to O-linked β-N-acetylglucosamine (O-GlcNAc) modification, which is a nutrient-sensitive post-translational modification. Here we found that unc-51 like autophagy activating kinase 1 (ULK1), a glucose-sensitive kinase, interacts with PKM2 and phosphorylates PKM2 at Ser333. Ser333 phosphorylation antagonizes PKM2 O-GlcNAcylation, promotes its tetramer formation and enzymatic activity, and decreases its nuclear localization. As PKM2 is known to have a nuclear role in regulating c-Myc, we also show that PKM2-S333 phosphorylation inhibits c-Myc expression. By downregulating glucose consumption and lactate production, PKM2 pS333 attenuates the Warburg effect. Through mouse xenograft assays, we demonstrate that the phospho-deficient PKM2-S333A mutant promotes tumor growth in vivo. In conclusion, we identified a ULK1-PKM2-c-Myc axis in inhibiting breast cancer, and a glucose-sensitive phosphorylation of PKM2 in modulating the Warburg effect.

Abstract 728: Oral TGF-beta receptor1 inhibitor vactosertib promotes osteosarcoma regression by targeting tumor proliferation and enhancing anti-tumor immunity

Abstract Osteosarcoma (OS) is an aggressive malignant bone cancer, with the lung as the most frequent site of metastasis. Unresectable pulmonary metastasis remains a significant challenge with a survival rate of less than 20%. Identification of novel therapeutic strategies are desperately needed. Transforming growth factor-β1 (TGF-β) is a potent immune suppressive cytokine in OS tumor microenvironment (TME). TGF-β1 expression is increased in the sera and tumor tissues of OS patients and this increase is associated with high-grade OS and lung metastases. Therefore, blocking TGF-β1 signaling may be a novel therapy for OS treatment. In this study, we show that blocking TGF-β1 signaling using the orally bioavailable small molecule TGF-βR1 inhibitor, Vactosertib, significantly inhibited OS proliferation in vitro and in vivo. Notably, Vactosertib inhibits c-Myc expression in the OS cells and oral administration of Vactosertib significantly reduces OS growth in vivo. Vactosertib increased immune effectors (e.g., IFNγ+CD8+ cells and NK cells) and inhibited immune suppressors (e.g., M2-like TAM, MDSC) in the OS TME. Our results suggest that inhibition of TGF-β1 signaling is an effective therapeutic strategy against OS through a multi-pronged approach that targets tumor intrinsic and extrinsic factors to achieve optimal immune-effector functions and maximal clinical response. Citation Format: Sung Hee Choi, Jay Myers, Suzanne Tomchuck, Melissa Bonner, Saada Eid, Daniel Kingsley, Kristen VanHeyst, Seong-Jin Kim, Byung-Gyu Kim, Alex Y. Huang. Oral TGF-beta receptor1 inhibitor vactosertib promotes osteosarcoma regression by targeting tumor proliferation and enhancing anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 728.

Mature microRNA-binding protein QKI promotes microRNA-mediated gene silencing

ABSTRACT Although Argonaute (AGO) proteins have been the focus of microRNA (miRNA) studies, we observed AGO-free mature miRNAs directly interacting with RNA-binding proteins, implying the sophisticated nature of fine-tuning gene regulation by miRNAs. To investigate microRNA-binding proteins (miRBPs) globally, we analyzed PAR-CLIP data sets to identify RBP quaking (QKI) as a novel miRBP for let-7b. Potential existence of AGO-free miRNAs were further verified by measuring miRNA levels in genetically engineered AGO-depleted human and mouse cells. We have shown that QKI regulates miRNA-mediated gene silencing at multiple steps, and collectively serves as an auxiliary factor empowering AGO2/let-7b-mediated gene silencing. Depletion of QKI decreases interaction of AGO2 with let-7b and target mRNA, consequently controlling target mRNA decay. This finding indicates that QKI is a complementary factor in miRNA-mediated mRNA decay. QKI, however, also suppresses the dissociation of let-7b from AGO2, and slows the assembly of AGO2/miRNA/target mRNA complexes at the single-molecule level. We also revealed that QKI overexpression suppresses cMYC expression at post-transcriptional level, and decreases proliferation and migration of HeLa cells, demonstrating that QKI is a tumour suppressor gene by in part augmenting let-7b activity. Our data show that QKI is a new type of RBP implicated in the versatile regulation of miRNA-mediated gene silencing.

Acetylcorynoline Induces Apoptosis and G2/M Phase Arrest through the c-Myc Signaling Pathway in Colon Cancer Cells.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide, and despite advances in treatment, survival rates are still low; therefore, the development of novel drugs is imperative. Acetylcorynoline (ACN) is derived from Corydalis ambigua Cham. et Schltdl tubers. The effect of ACN on colon cancer is still unknown. Therefore, we investigated its potential effects. Our data showed that ACN inhibited cell viability and proliferation. Moreover, ACN induced apoptosis and cell cycle arrest by inhibiting cell growth. In the present study, we hypothesized that ACN regulates c-Myc through CNOT2 or MID1IP1. ACN reduced the protein expression of oncogenic genes, decreased c-Myc half-life, and rapidly inhibited the serum stimulation response. Moreover, knockdown of CNOT2 and MID1IP1 with ACN increased apoptosis and further reduced the expression of oncogenes. In addition, ACN exhibited a synergistic effect with low-dose 5-fluorouracil (5-FU) and doxorubicin (Dox). Collectively, our data demonstrate that ACN inhibited c-Myc expression through CNOT2 and MID1IP1, and induced apoptosis. These findings indicate the potential of ACN as a therapeutic agent against colon cancer.

Selinexor Synergizes CX4945 on Anti-Tumor Effect By Targeting XPO1/Ikros/c-Myc Signaling in T-Cell Acute Lymphoblastic Leukemia

Background Acute lymphocytic leukemia (ALL) is an aggressive hematologic malignancy with poor outcomes. The IKZF1 (Ikaros) gene plays a crucial role in normal hematopoiesis as well as acts as a leukemia suppressor in ALL. Casein kinase II (CK2) inhibitor, CX4945, has shown potential function in restoring Ikaros on transcriptional repression of target genes in ALL. Exportin-1 (XPO1) is a critical mediator of nuclear export, which is essential for regulating the cell cycle and proliferation of normal and malignant tissues. Increased expression of XPO1 has been observed in various types of cancer, including ALL. In this study, we investigated the combined effects of Selinexor and CX4945 in T-cell ALL (T-ALL) and explored the underlying mechanisms. Methods Cell Counting Kit-8(CCK-8) was used for cell viability assay, and Annexin-V/PI staining following flow cytometry analysis for apoptosis. qPCR was used for gene expression in CEM and Molt4 T-ALL cell lines. CalcuSyn analysis was performed for a synergistic effect. Results Treatment of CX4945 or Selinexor significantly led to cell proliferation arrest of CEM and Molt4 cells in a dose-dependent manner. The combination of Selinexor with CX4945 significantly enhanced the cell proliferation arrest of CEM and Molt4 cells versus the single drug controls, and CalcuSyn analysis exhibited a synergistic effect of the two drugs in the cells (Fig.1A, B). The combination also significantly increased the apoptotic cells compared to the single-drug controls (Fig.1C). c-Myc oncogene plays an essential role in human cancers. Our results showed that c-Myc mRNA level was significantly higher expressed in the cohort of T-ALL patients compared to that of normal bone marrow controls (Fig.1D). To gain insight into the underlying mechanism of the synergy, we observed the effect of the drugs on the expression of c-Myc. Results showed that the combination of Selinexor with CX4945 significantly down-regulated the expression of c-Myc compared to the single-drug controls in CEM and Molt4 cells (Fig.1E). Moreover, the combination of Selinexor with CX4945 significantly enhanced the cell growth arrest in primary cells from T-ALL patients compared to single drug controls (Fig.1F). Taken together, our data indicated the synergistic effect of Selinexor with CX4945 on cell proliferation arrest and apoptosis by down-regulation of c-Myc expression. We previously reported that Ikaros directly regulates c-Myc transcription in ALL and CX4945 suppresses c-Myc expression in a Ikaros-dependent manner. Also, c-Myc is the cargo of XPO1. Thus, our results in this study reveal a model that treatment with XPO1 inhibitor, Selinexor prevents the nuclear transport of c-Myc and leads to its nuclear accumulation and down-regulation of c-Myc expression. The combination of Selinexor and CX4945 showed the synergistic anti-tumor effect by suppressing c-Myc expression in both transcriptional and post-transcriptional levels. The mechanism model is summarized in Fig.1G. ConclusionsThe combination of Selinexor and CX4945 has synergistic effects on cell proliferation arrest and apoptosis in T-ALL by targeting the XPO1/IKROS/c-Myc signaling. Our results also provide experimental evidence for the new combination of Selinexor and CX4945 as a new potential therapeutic option for T-ALL patients.

Involvement of cardiac glycosides targeting Na/K-ATPase in their inhibitory effects on c-Myc expression via its transcription, translation and proteasomal degradation.

Cardiac glycosides (CGs) have been used for decades to treat heart failure and arrhythmic diseases. Recent non-clinical and epidemiological findings have suggested that CGs exhibit anti-tumor activities. Therefore, CGs may be repositioned as drugs for the treatment of cancer. A detailed understanding of the anti-cancer mechanisms of CGs is essential for their application to the treatment of targetable cancer types. To elucidate the factors associated with the anti-tumor effects of CGs, we performed transcriptome profiling on human multiple myeloma AMO1 cells treated with periplocin, one of the CGs. Periplocin significantly down-regulated the transcription of MYC (c-Myc), a well-established oncogene. Periplocin also suppressed c-Myc expression at the protein levels. This repression of c-Myc was also observed in several cell lines. To identify target proteins for the inhibition of c-Myc, we generated CG-resistant (C9) cells using a sustained treatment with digoxin. We confirmed that C9 cells acquired resistance to the inhibition of c-Myc expression and cell proliferation by CGs. Moreover, the sequencing of genomic DNA in C9 cells revealed the mutation of D128N in α1-Na/K-ATPase, indicating the target protein. These results suggest that CGs suppress c-Myc expression in cancer cells via α1-Na/K-ATPase, which provides further support for the anti-tumor activities of CGs.

SHMT2 regulates esophageal cancer cell progression and immune Escape by mediating m6A modification of c-myc

BackgroundIn recent years, the role of altered cellular metabolism in tumor progression has attracted widespread attention. Related metabolic enzymes have also been considered as potential cancer therapeutic targets. Serine hydroxymethyltransferase 2 (SHMT2) has been reported to be upregulated in several cancers and associated with poor prognosis. However, there are few studies of SHMT2 in esophageal cancer (EC), and the related functions and mechanisms also need to be further explored.MethodsIn this study, we first analyzed SHMT2 expression in EC by online database and clinical samples. Then, the biological functions of SHMT2 in EC were investigated by cell and animal experiments. The intracellular m6A methylation modification levels were also evaluated by MeRIP. Linked genes and mechanisms of SHMT2 were analyzed by bioinformatics and rescue experiments.ResultsWe found that SHMT2 expression was abnormally upregulated in EC and associated with poor prognosis. Functionally, SHMT2 silencing suppressed c-myc expression in an m6A-dependent manner, thereby blocking the proliferation, migration, invasion and immune escape abilities of EC cells. Mechanistically, SHMT2 encouraged the accumulation of methyl donor SAM through a one-carbon metabolic network, thereby regulating the m6A modification and stability of c-myc mRNA in a METTL3/FTO/ALKBH5/IGF2BP2-dependent way. In vivo animal experiments also demonstrated that SHMT2 mediated MYC expression by m6A-methylation modification, thus boosting EC tumorigenesis.ConclusionIn conclusion, our data illustrated that SHMT2 regulated malignant progression and immune escape of EC cell through c-myc m6A modification. These revealed mechanisms related to SHMT2 in EC and maybe offer promise for the development of new therapeutic approaches.

A Phase 2 Study of Fedratinib in Patients with MDS/MPN and Chronic Neutrophilic Leukemia

Introduction MDS/MPNs are clinically and molecularly complex diseases that exhibit proliferative symptoms and aggressive clinical courses. Evaluation of mutational patterns and gene expression profiles suggest these diseases should be viewed as a spectrum rather than distinct disease entities. Treatment options are limited and poorly defined as patients (pts) are often excluded from clinical trials. The JAK1/JAK2 inhibitor, ruxolitinib, has shown clinical benefit in pts with MDS/MPN and pts harboring CSF3R mutations. The experience of JAK2 inhibitors in myelofibrosis (MF) has shown that non-JAK2 kinase targets of JAK inhibitors may result in unique profiles of clinical benefit. Fedratinib is a JAK2 inhibitor approved for higher-risk MF. Compared to ruxolitinib, it has a broader kinase inhibition profile which may convey enhanced efficacy in high-risk, molecularly complex disease. Fedratinib potently inhibits FLT3 and BRD4 and potently suppresses c-Myc expression which may have biologic relevance in MDS/MPN. Study Design This is a phase 2, multi-institutional, investigator-initiated clinical trial (NCT05177211) assessing the efficacy of fedratinib in pts with atypical chronic myeloid leukemia (aCML), chronic neutrophilic leukemia (CNL), MDS/MPN-unclassifiable (MDS/MPN-U), and MDS/MPN-ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) per 2016 WHO classification. Inclusion criteria included splenomegaly (≥ 5 cm below left costal margin or ≥ 450 cc) and/or significant disease-related symptoms (MPN TSS ≥ 10). Pts with a platelet count < 35 x 10 9/L or peripheral/marrow blasts > 10% were excluded. There was no exclusion based on prior treatment. The primary endpoint of this ongoing study is overall response rate defined as complete or partial response or clinical benefit at 24 weeks per proposed MDS/MPN IWG response criteria. C-Myc (a potential biomarker for response) was stained in the bone marrow collected at baseline and week 24. C-Myc expression product was scored by multiplying % positive cells by intensity (0 = none, 1 = mild, 2 = moderate, 3 = marked). Fedratinib was given at a dose of 400 mg daily. Planned enrollment is 25 pts with an interim analysis completed after 9 pts are evaluable for efficacy. Results At time of data cut-off, 10 pts have been enrolled with a median follow-up of 5 months. Eight pts remain on treatment. Baseline demographics, genetic makeup, and treatment history are shown in table 1. Enrolled pts include 1 with aCML, 4 with CNL, 4 with MDS/MPN-RS-T, and 1 with MDS/MPN-U. Three or more mutations were present in 7 (70%) pts. Three of 5 (60%) evaluable pts responded at week 24. This included 3 (75%) symptom responses and 1 (20%) spleen response (1 pt with both). Six pts have completed 12 weeks of treatment with 1 spleen response and 2 symptoms responses (Figure 1). Among 6 pts with baseline splenomegaly who received 12 weeks of treatment, spleen volume decreased in 5 (83%) by an average of -23% (+5% to -71%). Among 5 pts with significant baseline symptom burden who received 12 weeks of treatment, 4 (80%) experienced an improvement in symptom burden by an average of -43% (range 0% to -76%). One pt who discontinued treatment prior to week 8 for reasons unrelated to disease or treatment was considered a spleen and symptom non-responder despite experiencing a 48% symptom improvement at week 4. At baseline, C-Myc expression was demonstrated by IHC staining in a median of 10% of cells (5-15%). Average baseline c-Myc expression product (% positive cells * staining intensity) was 26.5 (range 10-37.5). In pts with paired samples (n = 4), c-Myc expression product decreased in all cases by an average of 51% (25%-85%), p = 0.02. Ten pts were evaluable for safety. The most common AEs occurring in >2 pts were anemia, platelet count decrease, diarrhea, nausea, muscle cramp, and constipation. Grade ≥3 AEs were anemia (40%) and neutropenia (10%). There were no grade ≥ 3 non-hematologic AEs. Two pts discontinued study treatment: one due to disease progression after initial response and one due to pt decision unrelated to disease or treatment. Conclusion: Fedratinib demonstrates promising clinical efficacy in MDS/MPN and CNL pts with proliferative features. The safety profile is consistent with prior experience. Fedratinib's unique kinase inhibition profile may provide a mechanism for enhanced effectiveness in this pt population. Updated results will be presented at the meeting.

UPR-Induced miR-616 Inhibits Human Breast Cancer Cell Growth and Migration by Targeting c-MYC.

C/EBP homologous protein (CHOP), also known as growth arrest and DNA damage-inducible protein 153 (GADD153), belongs to the CCAAT/enhancer-binding protein (C/EBP) family. CHOP expression is induced by unfolded protein response (UPR), and sustained CHOP activation acts as a pivotal trigger for ER stress-induced apoptosis. MicroRNA-616 is located within an intron of the CHOP gene. However, the regulation of miR-616 expression during UPR and its function in breast cancer is not clearly understood. Here we show that the expression of miR-616 and CHOP (host gene of miR-616) is downregulated in human breast cancer. Both miR-5p/-3p arms of miR-616 are expressed with levels of the 5p arm higher than the 3p arm. During conditions of ER stress, the expression of miR-616-5p and miR-616-3p arms was concordantly increased primarily through the PERK pathway. Our results show that ectopic expression of miR-616 significantly suppressed cell proliferation and colony formation, whereas knockout of miR-616 increased it. We found that miR-616 represses c-MYC expression via binding sites located in its protein coding region. Furthermore, we show that miR-616 exerted growth inhibitory effects on cells by suppressing c-MYC expression. Our results establish a new role for the CHOP locus by providing evidence that miR-616 can inhibit cell proliferation by targeting c-MYC. In summary, our results suggest a dual function for the CHOP locus, where CHOP protein and miR-616 can cooperate to inhibit cancer progression.

Non-fused imidazole-biphenyl analogs repress triple-negative breast cancer growth by mainly stabilizing the c-MYC G-quadruplex via a multi-site binding mode

As oncogene c-MYC is abnormally expressed during TNBC pathogenesis, stabilizing its promoter G-quadruplex (G4), which may thus inhibit c-MYC expression and promote DNA damage, may be a potential anti-TNBC strategy. However, large quantities of potential G4-forming sites exist in the human genome, which represents a potential drug selectivity problem. In order to achieve better recognition for c-MYC G4, we herein presented a new approach of designing small-molecule ligands by linking tandem aromatic rings with the c-MYC G4 selective binding motifs. Thus, a series of non-fused, conformation-tunable imidazole-biphenyl analogs were designed and synthesized. Among them, the optimal ligand appeared more effective on stabilizing c-MYC G4 than other types of G4s possibly through an adaptive, multi-site binding mode involved of end-stacking, groove-binding and loop-interacting. Then, the optimal ligand exerted good inhibitory activity on c-MYC expression and induced remarkable DNA damage, leading to the occurrence of G2/M phase arrest, apoptosis and autophagy. Furthermore, the optimal ligand exhibited potent antitumor effects in a TNBC xenograft tumor model. To sum up, this work offers new insights for the development of selective c-MYC G4 ligands against TNBC.

SNHG18 inhibits bladder cancer cell proliferation by increasing p21 transcription through destabilizing c-Myc protein

BackgroundLong non-coding RNAs (lncRNAs) have been confirmed to play important roles in various cancers including bladder cancer (BC). The precise expression pattern of lncRNA small nucleolar RNA host gene 18 (SNHG18) in BC and its mechanisms of action have not been fully explored.Materials and methodsThe expression of SNHG18 was evaluated by RT-qPCR in bladder cancer clinical samples and human bladder cancer cell lines, and stable cell lines overexpressing SNHG18 were constructed. The effect of SNHG18 on the proliferation of bladder cancer cells was detected by soft agar colony formation test, ATP activity test and subcutaneous tumorigenesis model in nude mice. The specific mechanism of SNHG18 inhibition of bladder cancer proliferation was studied by flow cytometry, western blotting, dual luciferase reporter gene assay and protein degradation assay.ResultsWe found that SNHG18 is significantly downregulated in BC tissues and cell lines. Kaplan–Meier analysis showed that SNHG18 expression is positively correlated with survival in BC patients. Ectopic overexpression of SNHG18 significantly inhibited the proliferation of BC cells in vitro and in vivo. Further mechanistic investigations demonstrated that SNHG18 inhibited c-Myc expression by modulating the ubiquitination-proteasome pathway and that c-Myc is the critical transcription factor that mediates SNHG18 inhibition of BC growth by directly binding to the p21 promoter, which was attributed with significant p21 accumulation.ConclusionsSNHG18 promotes the transcription and expression of p21 by inhibiting c-Myc expression, leading to G0-G1 arrest and inhibiting the proliferation of bladder cancer cells. These findings highlight a novel cell cycle regulatory mechanism involving the SNHG18/c-Myc/p21 pathway in BC pathogenesis and could potentially lead to new lncRNA-based diagnostics and/or therapeutics for BC.

Potent bromodomain and extraterminal domain inhibitor JAB-8263 suppresses MYC expression and exerts anti-tumor activity in colorectal cancer models.

The overexpression of the MYC gene plays an important role in the occurrence, development and evolution of colorectal cancer (CRC). Bromodomain and extraterminal domain (BET) inhibitors can decrease the function BET by recognizing acetylated lysine residues, thereby downregulating the expression of MYC. To investigate the inhibitory effect and mechanism of a BET inhibitor on CRC cells. The effect of the BET inhibitor JAB-8263 on the proliferation of various CRC cell lines was studied by CellTiter-Glo method and colony formation assay. The effect of JAB-8263 on the cell cycle and apoptosis of CRC cells was studied by propidium iodide staining and Annexin V/propidium iodide flow assay, respectively. The effect of JAB-8263 on the expression of c-MYC, p21 and p16 in CRC cells was detected by western blotting assay. The anti-tumor effect of JAB-8263 on CRC cells in vivo and evaluation of the safety of the compound was predicted by constructing a CRC cell animal tumor model. JAB-8263 dose-dependently suppressed CRC cell proliferation and colony formation in vitro. The MYC signaling pathway was dose-dependently inhibited by JAB-8263 in human CRC cell lines. JAB-8263 dose-dependently induced cell cycle arrest and apoptosis in the MC38 cell line. SW837 xenograft model was treated with JAB-8263 (0.3 mg/kg for 29 d), and the average tumor volume was significantly decreased compared to the vehicle control group (P < 0.001). The MC38 syngeneic murine model was treated with JAB-8263 (0.2 mg/kg for 29 d), and the average tumor volume was significantly decreased compared to the vehicle control group (P = 0.003). BET could be a potential effective drug target for suppressing CRC growth, and the BET inhibitor JAB-8263 can effectively suppress c-MYC expression and exert anti-tumor activity in CRC models.

AXL upregulates c‑Myc expression through AKT and ERK signaling pathways in breast cancers.

Breast cancer (BC) is common worldwide. c-Myc and AXL are both overexpressed in BC, promoting its progression. The present study aimed to investigate the role of AXL in c-Myc expression in BC. Overexpression of AXL increased c-Myc expression while knockdown of AXL decreased c-Myc expression as determined by western blot analysis. Pharmaceutical inhibition of AXL also suppressed c-Myc expression. AKT and ERK inhibitor LY294002 and U0126 suppressed c-Myc expression, respectively. AXL overexpression which activates AKT and ERK signaling, upregulates c-Myc expression, while kinase-dead AXL which cannot activate AKT and ERK signaling, does not upregulate c-Myc expression, emphasizing the important role of these two signaling pathways in c-Myc upregulation. Finally, expression data of BC tissues from The Cancer Proteome Atlas displayed an association between AXL and c-Myc. Taken together, the present study revealed that AXL upregulates c-Myc expression through AKT and ERK signaling pathways in BC.

Tasquinimod suppresses tumor cell growth and bone resorption by targeting immunosuppressive myeloid cells and inhibiting c-MYC expression in multiple myeloma

BackgroundImmunotherapy emerged as a promising treatment option for multiple myeloma (MM) patients. However, therapeutic efficacy can be hampered by the presence of an immunosuppressive bone marrow microenvironment including myeloid cells....

Ophiopogonin D increase apoptosis by activating p53 via ribosomal protein L5 and L11 and inhibiting the expression of c-Myc via CNOT2.

Ophiopogonin D (OP-D), which is extracted from the root tuber of Ophiopogon japonicus, is well known for its anti-inflammatory, anti-oxidant, and anti-cancer effects. It is also therapeutic for various diseases such as diabetic myocardial injuries, obesity, atopic dermatitis, and osteoporosis. However, there are insufficient reports on the anti-cancer effects and molecular mechanisms of OP-D in colorectal cancer. Therefore, this study aimed to investigate the anti-cancer-modulating effect of OP-D on colorectal cancer. The study proved that OP-D (20-40 uM) has significant cell viability inhibition and anti-proliferative effects in Cell Counting Kit-8 (CCK-8) assay and colony formation assay. In addition, our immunofluorescence analysis data showed that OP-D (40 uM) inhibited the expression of Ki67, a cell proliferation marker, and confirmed that OP-D could induce nucleolar stress by depletion of IPO7 and XPO1. Furthermore, our western blot data showed that OP-D induced p53 expression via ribosomal protein (RP) L5 or L11 and inhibited c-Myc expression through CNOT2 in a dose-dependent manner. Additionally, OP-D regulated cyclin D1 and CDK4, which are well known as cell cycle regulatory proteins. OP-D consistently inhibited the phosphorylation of AKT expression in a dose-dependent manner. Furthermore, OP-D shortened c-Myc's half-life in a time-dependent manner. Furthermore, CNOT2 knockdown enhanced the inhibitory effect of OP-D on c-Myc in colon cancer cells. Besides that, we confirmed that OP-D has a combinational anti-cancer effect of 5-FU or doxorubicin to reduce cell viability and induce apoptosis through p53 and c-Myc regulation. Altogether, our results suggest that OP-D regulates colon cancer cell proliferation and induces apoptosis by inhibiting c-Myc expression via activation of p53 and CNOT2 regulation. The study demonstrated that OP-D may be a promising natural anti-cancer agent for the treatment of colorectal cancer.

A new inhibitor of human peptide deformylase suppresses cell proliferation and induces cell apoptosis and autophagy in cancers.

Human peptide deformylase (hsPDF) has been found overexpressed in many cancer cells and its inhibitors exhibit antitumor activity. Studies were performed to validate that hsPDF is a good antitumor target. The inhibitory effect of PDF64 on hsPDF enzymatic activity was measured and confirmed by computation analysis. Antiproliferation activity was determined and in-vivo antitumor activity were analyzed in HCT116 and HL60 nude mice xenografts. Mitochondrial membrane potential (MMP), cell apoptosis, and autophagic cell death were analyzed by flow cytometry. ATP level was quantified using an ATP assay kit. Protein expression and kinase phosphorylation were determined by western blotting. A new hsPDF inhibitor PDF64 was identified. It showed evident antiproliferation activity in 10 cancer cells and significantly suppressed tumor growth in HCT116 and HL60 xenografts. It induced an obvious decrease in MMP and caused apparent cell apoptosis and autophagy in HCT116 and Jurkat cells. PDF64 treatment also led to an evident decrease in cellular ATP levels in these cells. Moreover, PDF64 downregulated c-Myc expression and had some effects on extracellular regulated protein kinases (ERK) and protein kinase B (Akt)/ mammalian target of rapamycin (mTOR) pathways. PDF64 exhibited good antitumor effects both in vivo and in vitro . It caused cell apoptosis and autophagic death in HCT116 and Jurkat cells. The effects may be mediated by inhibiting c-Myc expression and ERK or PI3K-Akt-mTOR pathway. Therefore, PDF64 may be a promising reagent for antitumor drug development, which further supports that hsPDF is a good antitumor drug target.

Cordycepin inhibited the retinoblastoma cell proliferation, migration, and invasion as well as lung metastasis via modulating c-Myc/cyclin D1 pathway.

This study aims to investigate cordycepin's effects on the proliferation, migration, and invasion of retinoblastoma (RB) cells and its regulatory mechanism. In this study, it was found that cordycepin inhibited RB cell proliferation, migration, and invasion in vitro, and pulmonary metastasis in vivo. c-Myc was a downstream target of cordycepin, and cordycepin significantly suppressed c-Myc expression, and c-Myc overexpression markedly counteracted the impacts of cordycepin on RB cell proliferation, migration, and invasion. c-Myc was positively correlated with the cell cycle pathway. Cordycepin restrained cyclin D1 expression, and c-Myc overexpression rescued this effect. In conclusion, cordycepin targets the c-Myc/cyclin D1 pathway, thereby suppressing the malignant biological behaviors of RB cells.

The Antitumor Effect of Timosaponin A3 through c-Myc Inhibition in Colorectal Cancer Cells and Combined Treatment Effect with 5-FU or Doxorubicin.

Timosaponin A3 (TA3), extracted from the rhizome of Anemarrhena asphodeloides Bunge, has been reported to affect various diseases, such as cancer, Alzheimer’s disease, and allergies. However, the underlying molecular mechanisms and impacts are largely unknown. In the present study, we hypothesized that TA3 induces apoptosis through the inhibition of c-Myc expression via CNOT2 or MID1IP1 in HCT116. An MTT assay and colony formation assay were used to measure cell viability and proliferation. The protein expression of apoptotic markers and oncogenes was measured using immunoblotting and immunofluorescence assays. The interaction between MID1IP1 and c-Myc was confirmed by performing an immunoprecipitation assay. TA3 markedly inhibited colon cancer cell proliferation. Consistently, TA3 regulated the apoptotic proteins pro-PARP and caspase 3. TA3 inhibited the half-life of c-Myc and suppressed its expression in response to serum stimulation. In addition, TA3 enhanced the apoptotic effects of doxorubicin and 5-FU in colon cancer cells. Altogether, our results reveal a mechanism by which TA3 induces apoptosis through inhibiting c-Myc expression via CNOT2 or MID1IP1 in HCT116, which may help in the development of new therapies for colon cancer based on TA3 in the future.