Small-molecule c-Myc inhibitor, 10058-F4, inhibits proliferation, downregulates human telomerase reverse transcriptase and enhances chemosensitivity in human hepatocellular carcinoma cells

Targeting Metabolic-Redox Nexus to Regulate Drug Resistance: From Mechanism to Tumor Therapy

Drug resistance is currently one of the biggest challenges in cancer treatment. With the deepening understanding of drug resistance, various mechanisms have been revealed, including metabolic reprogramming and alterations of redox balance. Notably, metabolic reprogramming mediates the survival of tumor cells in harsh environments, thereby promoting the development of drug resistance. In addition, the changes during metabolic pattern shift trigger reactive oxygen species (ROS) production, which in turn regulates cellular metabolism, DNA repair, cell death, and drug metabolism in direct or indirect ways to influence the sensitivity of tumors to therapies. Therefore, the intersection of metabolism and ROS profoundly affects tumor drug resistance, and clarifying the entangled mechanisms may be beneficial for developing drugs and treatment methods to thwart drug resistance. In this review, we will summarize the regulatory mechanism of redox and metabolism on tumor drug resistance and highlight recent therapeutic strategies targeting metabolic-redox circuits, including dietary interventions, novel chemosynthetic drugs, drug combination regimens, and novel drug delivery systems.

C-Myc inhibition intensified the anti-leukemic properties of Imatinib in chronic myeloid leukemia cells

BACKGROUND

Due to its remarkable efficacy in producing hematologic, cytogenetic, and molecular remissions, the FDA approved Imatinib as the first-line treatment for newly diagnosed Chronic Myeloid Leukemia (CML) patients. However, in some patients, failure to completely eradicate leukemic cells and the escape of these cells from death will lead to the development of resistance to Imatinib, and many are concerned about the prospects of this Tyrosine Kinase Inhibitor (TKI). It has been documented that the compensatory overexpression of c-Myc is among the most critical mechanisms that promote drug efflux and resistance in CML stem cells.

METHODS

In order to examine the potential of c-Myc inhibition through the use of 10058-F4 to enhance the anti-leukemic properties of Imatinib, we conducted trypan blue and MTT assays. Additionally, we employed flow cytometric analysis and qRT-PCR to assess the effects of this combination on cell cycle progression and apoptosis.

RESULTS

The findings of our study indicate that the combination of 10058-F4 and Imatinib exhibited significantly stronger anti-survival and anti-proliferative effects on CML-derived-K562 cells in comparison to either agent administered alone. It is noteworthy that these results were also validated in the CML-derived NALM-1 cell line. Molecular analysis of this synergistic effect revealed that the inhibition of c-Myc augmented the efficacy of Imatinib by modulating the expression of genes related to cell cycle, apoptosis, autophagy, and proteasome.

CONCLUSIONS

Taken together, the findings of this investigation have demonstrated that the suppression of the c-Myc oncoprotein through the use of 10058-F4 has augmented the effectiveness of Imatinib, suggesting that this amalgamation could offer a fresh perspective on an adjunctive treatment for individuals with CML. Nevertheless, additional scrutiny, encompassing in-vivo examinations and clinical trials, is requisite.

MYC in liver cancer: mechanisms and targeted therapy opportunities

MYC, a major oncogenic transcription factor, regulates target genes involved in various pathways such as cell proliferation, metabolism and immune evasion, playing a critical role in the tumor initiation and development in multiple types of cancer. In liver cancer, MYC and its signaling pathways undergo significant changes, exerting a profound impact on liver cancer progression, including tumor proliferation, metastasis, dedifferentiation, metabolism, immune microenvironment, and resistance to comprehensive therapies. This makes MYC an appealing target, despite it being previously considered an undruggable protein. In this review, we discuss the role and mechanisms of MYC in liver physiology, chronic liver diseases, hepatocarcinogenesis, and liver cancer progression, providing a theoretical basis for targeting MYC as an ideal therapeutic target for liver cancer. We also summarize and prospect the strategies for targeting MYC, including direct and indirect approaches to abolish the oncogenic function of MYC in liver cancer.

Combination of Everolimus and Bortezomib Inhibits the Growth and Metastasis of Bone and Soft Tissue Sarcomas via JNK/p38/ERK MAPK and AKT Pathways

The combination of the mammalian target of rapamycin and proteasome inhibitors is a new treatment strategy for various tumors. Herein, we investigated the synergistic effect of everolimus and bortezomib on tumor growth and metastasis in bone and soft tissue sarcomas. The antitumor effects of everolimus and bortezomib were assessed in a human fibrosarcoma (FS) cell line (HT1080) and mouse osteosarcoma (OS) cell line (LM8) by MTS assays and Western blotting. The effects of everolimus and bortezomib on HT1080 and LM8 tumor growth in xenograft mouse models were evaluated using tumor volume and the number of metastatic nodes of the resected lungs. Immunohistochemistry was used to evaluate cleaved PARP expression. The combination therapy decreased FS and OS cell proliferation compared with either drug alone. This combination induced more intense p-p38, p-JNK, and p-ERK and activated apoptosis signals, such as caspase-3, compared with single-agent treatment. The combination treatment reduced p-AKT and MYC expression, decreased FS and OS tumor volumes, and suppressed lung metastases of OS. The combination therapy inhibited tumor growth in FS and OS and metastatic progression of OS via the JNK/p38/ERK MAPK and AKT pathways. These results could aid in the development of new therapeutic strategies for sarcomas.

Targeted downregulation of MYC mediated by a highly efficient lactobionic acid-based glycoplex to enhance chemosensitivity in human hepatocellular carcinoma cells

The chemosensitization of tumor cells by gene therapy represents a promising strategy for hepatocellular carcinoma (HCC) treatment. In this regard, HCC-specific and highly efficient gene delivery nanocarriers are urgently needed. For this purpose, novel lactobionic acid-based gene delivery nanosystems were developed to downregulate c-MYC expression and sensitize tumor cells to low concentration of sorafenib (SF). A library of tailor-made cationic glycopolymers, based on poly(2-aminoethyl methacrylate hydrochloride) (PAMA) and poly(2-lactobionamidoethyl methacrylate) (PLAMA) were synthesized by a straightforward activators regenerated by electron transfer atom transfer radical polymerization. The nanocarriers prepared with PAMA₁₁₄-co-PLAMA₂₀ glycopolymer were the most efficient for gene delivery. These glycoplexes specifically bound to the asialoglycoprotein receptor and were internalized through the clathrin-coated pit endocytic pathway. c-MYC expression was significantly downregulated by MYC short-hairpin RNA (MYC shRNA), resulting in efficient inhibition of tumor cells proliferation and a high levels apoptosis in 2D and 3D HCC-tumor models. Moreover, c-MYC silencing increased the sensitivity of HCC cells to SF (IC₅₀ for MYC shRNA+ SF 1.9 μM compared to 6.9 μM for control shRNA + SF). Overall, the data obtained demonstrated the great potential of PAMA₁₁₄-co-PLAMA₂₀/MYC shRNA nanosystems combined with low doses of SF for the treatment of HCC.

Pten associates with important gene regulatory network to fine-tune Müller glia-mediated zebrafish retina regeneration

Unlike mammals, zebrafish possess a remarkable ability to regenerate damaged retina after an acute injury. Retina regeneration in zebrafish involves the induction of Müller glia-derived progenitor cells (MGPCs) exhibiting stem cell-like characteristics, which are capable of restoring all retinal cell-types. The induction of MGPC through Müller glia-reprograming involves several cellular, genetic and biochemical events soon after a retinal injury. Despite the knowledge on the importance of Phosphatase and tensin homolog (Pten), which is a dual-specificity phosphatase and tumor suppressor in the maintaining of cellular homeostasis, its importance during retina regeneration remains unknown. Here, we explored the importance of Pten during zebrafish retina regeneration. The Pten gets downregulated upon retinal injury and is absent from the MGPCs, which is essential to trigger Akt-mediated cellular proliferation essential for retina regeneration. We found that the downregulation of Pten in the post-injury retina accelerates MGPCs formation, while its overexpression restricts the regenerative response. We observed that Pten regulates the proliferation of MGPCs not only through Akt pathway but also by Mmp9/Notch signaling. Mmp9-activity is essential to induce the proliferation of MGPCs in the absence of Pten. Lastly, we show that expression of Pten is fine-tuned through Mycb/histone deacetylase1 and Tgf-β signaling. The present study emphasizes on the stringent regulation of Pten and its crucial involvement during the zebrafish retina regeneration.

Noncanonical activation of GLI signaling in SOX2+ cells drives medulloblastoma relapse

SRY (sex determining region Y)-box 2 (SOX2)-labeled cells play key roles in chemoresistance and tumor relapse; thus, it is critical to elucidate the mechanisms propagating them. Single-cell transcriptomic analyses of the most common malignant pediatric brain tumor, medulloblastoma (MB), revealed the existence of astrocytic Sox2+ cells expressing sonic hedgehog (SHH) signaling biomarkers. Treatment with vismodegib, an SHH inhibitor that acts on Smoothened (Smo), led to increases in astrocyte-like Sox2+ cells. Using SOX2-enriched MB cultures, we observed that SOX2+ cells required SHH signaling to propagate, and unlike in the proliferative tumor bulk, the SHH pathway was activated in these cells downstream of Smo in an MYC-dependent manner. Functionally different GLI inhibitors depleted vismodegib-resistant SOX2+ cells from MB tissues, reduced their ability to further engraft in vivo, and increased symptom-free survival. Our results emphasize the promise of therapies targeting GLI to deplete SOX2+ cells and provide stable tumor remission.

Identification of a novel mechanism for reversal of doxorubicin-induced chemotherapy resistance by TXNIP in triple-negative breast cancer via promoting reactive oxygen-mediated DNA damage

Given that triple-negative breast cancer (TNBC) lacks specific receptors (estrogen and progesterone receptors and human epidermal growth factor receptor 2) and cannot be treated with endocrine therapy, chemotherapy has remained the mainstay of treatment. Drug resistance is reportedly the main obstacle to the clinical use of doxorubicin (DOX) in this patient population. Accordingly, screening molecules related to chemoresistance and studying their specific mechanisms has clinical significance for improving the efficacy of chemotherapy in TNBC patients. Thioredoxin-interacting protein (TXNIP) is a metabolism-related protein that plays a tumor suppressor role in various malignant tumors; however, the specific role of TXNIP in tumor chemoresistance has not been reported. In the present study, we explored the potential molecular mechanism of TXNIP in the chemoresistance of TNBC for the first time. The results showed that TXNIP inhibited the proliferation of TNBC drug-resistant cells and promoted apoptosis in vitro and in vivo. Furthermore, TXNIP promoted the synthesis of reactive oxygen species (ROS) and the accumulation of DNA damage caused by DOX and increased γ-H2AX levels in a time and dose-dependent manner. Moreover, ROS scavenger pretreatment could block DNA damage induced by TXNIP and restore the resistance of TNBC resistant cells to DOX to a certain extent. In addition, we found that the small molecule c-Myc inhibitor 10058-F4 promoted TXNIP expression, increased ROS synthesis in cells, and could enhance the cytotoxicity of chemotherapy drugs in vitro and in vivo when combined with DOX. These results indicated that c-Myc inhibitor 10058-F4 could induce TXNIP upregulation in TNBC drug-resistant cells, and the upregulated TXNIP increased the accumulation of ROS-dependent DNA damage, thereby decreasing chemotherapy resistance of TNBC. Our findings reveal a new mechanism of mediating drug resistance and provide a new drug combination strategy to overcome DOX resistance in TNBC.

Genetic and Epigenetic Signatures in Acute Promyelocytic Leukemia Treatment and Molecular Remission

Acute myeloid leukemia (AML) is an aggressive, heterogeneous group of malignancies with different clinical behaviors and different responses to therapy. For many types of cancer, finding cancer early makes it easier to treat. Identifying prognostic molecular markers and understanding their biology are the first steps toward developing novel diagnostic tools or therapies for patients with AML. In this study, we defined proteins and genes that can be used in the prognosis of different acute leukemia cases and found possible uses in diagnostics and therapy. We analyzed newly diagnosed acute leukemia cases positive for t (15; 17) (q22; q21) PML-RAR alpha, acute promyelocytic leukemia (APL). The samples of bone marrow cells were collected from patients at the diagnosis stage, as follow-up samples during standard treatment with all-trans retinoic acid, idarubicin, and mitoxantrone, and at the molecular remission. We determined changes in the expression of genes involved in leukemia cell growth, apoptosis, and differentiation. We observed that WT1, CALR, CAV1, and MYC genes’ expression in all APL patients with no relapse history was downregulated after treatment and could be potential markers associated with the pathology, thereby revealing the potential value of this approach for a better characterization of the prediction of APL outcomes.

Antitumor Effects of 10058-F4 and Curcumin in Combination Therapy for Pancreatic Cancer In Vitro and In Vivo

Background

Pancreatic cancer (PC) stands out as one of the most lethal cancers. Due to late diagnosis, only a fraction of patients can be resected. Although it still has significant adverse effects and poor results, the treatment is connected with better overall survival than the prior treatment. Thus, new alternative therapy for advanced PC is needed. Materials/Methods. The impact of 10058-F4 and curcumin combination therapy on apoptosis and cell growth in SW1990 pancreatic cancer cells were determined in vitro using the CCK-8 assay and flow cytometry of Annexin V-FITC/PI, and the in vivo antitumor effect was determined utilizing SW1990-bearing pancreatic tumor mouse models induced by subcutaneous implantation.

Results

At concentrations of (10 mol/L+2 mol/L), 10058-F4+curcumin obtained the highest rate of SW1990 cell death, and they had a beneficial effect on SW1990 pancreatic tumor-bearing animals. Furthermore, c-Myc, Akt phosphorylation, and the expression of apoptosis-related molecular were reduced, and the combination therapy modified the expression of apoptosis-related molecular.

Conclusions

In vitro and in vivo, the combination of 10058-F4 plus curcumin has antipancreatic cancer actions that are substantially effective.

WWP1 upregulation predicts poor prognosis and promotes tumor progression by regulating ubiquitination of NDFIP1 in intrahepatic cholangiocarcinoma

WW domain-containing E3 ubiquitin protein ligase1 (WWP1) is reported to be upregulated in many types of human cancers; however, its expression and function in intrahepatic cholangiocarcinoma (ICC) remain unknown. Here, in this study we investigated the expression pattern, clinical prognosis, tumor biological functions, and molecular mechanisms of WWP1 in ICC. The expression of WWP1 in patient tissues was detected by western blotting, immunohistochemistry (IHC), and immunofluorescence. CCK-8, colony formation, EdU, transwell, and xenograft models were used to explore the role of WWP1 in the proliferation and metastasis of ICC. Co-immunoprecipitation, mass spectrometry, chromatin immunoprecipitation, and immunofluorescence were performed to detect the potential mechanisms. Our study revealed that WWP1 was highly expressed in ICC, and high levels of WWP1 were associated with poor prognosis. Functionally, WWP1 overexpression enhanced the proliferation and metastasis of ICC cells and vice versa. Mechanistically, MYC could be enriched in the promoter region of WWP1 to facilitate its expression. Then, WWP1 targets Nedd4 family interacting protein1 (NDFIP1) and reduces NDFIP1 protein levels via ubiquitination. Downregulation of NDFIP1 in ICC cells rescued the effects of silenced WWP1 expression. WWP1 expression was also negatively correlated with the protein level of NDFIP1 in patient tissues. In conclusion, WWP1 upregulated by MYC promotes the progression of ICC via ubiquitination of NDFIP1, which reveals that WWP1 might be a potential therapeutic target for ICC.

The Wnt Signaling Pathway Inhibitors Improve the Therapeutic Activity of Glycolysis Modulators against Tongue Cancer Cells

Excessive glucose metabolism and disruptions in Wnt signaling are important molecular changes present in oral cancer cells. The aim of this study was to evaluate the effects of the combinatorial use of glycolysis and Wnt signaling inhibitors on viability, cytotoxicity, apoptosis induction, cell cycle distribution and the glycolytic activity of tongue carcinoma cells. CAL 27, SCC-25 and BICR 22 tongue cancer cell lines were used. Cells were treated with inhibitors of glycolysis (2-deoxyglucose and lonidamine) and of Wnt signaling (PRI-724 and IWP-O1). The effects of the compounds on cell viability and cytotoxicity were evaluated with MTS and CellTox Green tests, respectively. Apoptosis was evaluated by MitoPotential Dye staining and cell cycle distribution by staining with propidium iodide, followed by flow cytometric cell analysis. Glucose and lactate concentrations in a culture medium were evaluated luminometrically. Combinations of 2-deoxyglucose and lonidamine with Wnt pathway inhibitors were similarly effective in the impairment of oral cancer cells’ survival. However, the inhibition of the canonical Wnt pathway by PRI-724 was more beneficial, based on the glycolytic activity of the cells. The results point to the therapeutic potential of the combination of low concentrations of glycolytic modulators with Wnt pathway inhibitors in oral cancer cells.

Galactose-decorated liver tumor-specific nanoliposomes incorporating selective BRD4-targeted PROTAC for hepatocellular carcinoma therapy

This research deals with the development of asialoglycoprotein receptors (ASGPR) directed nanoliposomes incorporating a novel BRD4 (Bromodomain-containing protein 4) protein-targeted PROTAC (Proteolysis Targeting Chimera), ARV-825 (ARV) (GALARV), and to investigate the anticancer efficacy of GALARV for specific delivery in hepatocellular carcinoma. GALARV were prepared using the modified hydration method and characterized for their physicochemical properties as well as anticancer activity using 2D and 3D cell culture models. ARV and GALARV (93.83 ± 10.05 nm) showed significant in vitro cytotoxicity and apoptosis in hepatocellular carcinoma cells. GALARV also demonstrated a substantially higher intracellular concentration of ARV compared to non-targeted nanoliposomes (∼3 fold) and ARV alone (∼4.5 fold), showed good physical stability and negligible hemolysis. Immunoblotting results depicted substantial downregulation of target BRD4 protein, oncogenic c-Myc, apoptotic Bcl-2, and survivin proteins. Notably, GALARV treatment resulted in significant apoptosis and subsequent inhibition of the cell viability of 3D tumor spheroids of hepatocellular carcinoma. These results suggest that GALARV is a novel actively targeted PROTAC-based nanotherapeutic approach for hepatocellular carcinoma.

Inhibition of c-Myc using 10058-F4 induces anti-tumor effects in ovarian cancer cells via regulation of FOXO target genes

Ovarian cancer, characterized by rapid growth and asymptomatic development in the early stage, is the fifth common cancer in women. The deregulated expression of c-Myc in more than 50% of human tumors including ovarian cancer makes this oncogenic master transcription factor a potential therapeutic target for cancer treatment. In the present study, we evaluated the anti-tumor effects of 10058-F4, a small molecule c-Myc inhibitor, on ovarian cancer cells. We found that 10058-F4 not only inhibited the proliferation and clonal growth of ovarian cancer cells but also enhanced the cytotoxic effects of chemotherapeutic drugs. Our results also revealed that c-Myc inhibition using 10058-F4 increased the intracellular reactive oxygen species production coupled with suppressed expression of hTERT. RT-qPCR analysis indicated that 10058-F4 enhanced the mRNA levels of the forkhead box O (FOXO) family of transcription factors, including FOXO1, 3, and 4. Moreover, 10058-F4 induced G1 cell cycle arrest in 2008C13 ovarian cancer cells, along with increased expression of some key targets of FOXOs involved in the regulation of cell cycle such as p15, p21, p27, and GADD45A. The results of our study also showed that the 10058-F4-induced apoptosis in 2008C13 cell line was associated with the upregulation of FOXO downstream genes, including PUMA, Bim, and FasL. In conclusion, our results, for the first time, suggest that the anti-tumor effects of 10058-F4 in ovarian cancer cells might be mediated through upregulation of FOXO transcription factors and their key target genes involved in G1 cell cycle arrest, apoptosis, and autophagic cell death.

TAGLN Is Downregulated by TRAF6-Mediated Proteasomal Degradation in Prostate Cancer Cells

Transgelin (TAGLN, also named SM22) is an actin-associated protein and affects dynamics of actin filaments. Deregulation of TAGLN contributes to the development of different cancers, and it is commonly considered to be a tumor suppressor. TAGLN is usually downregulated in prostate cancer; however, the detailed functions of TAGLN in prostate cancer and how TAGLN is regulated remains unclear. In this study, we confirmed that TAGLN is downregulated in prostate cancer tissues and demonstrated that the downregulation of TAGLN occurs through proteasomal degradation. Next, we found that the expression level of TAGLN is inversely correlated with TRAF6. We screened more than 20 E2-E3 pairs by in vitro ubiquitination assay and found that the E2A-TRAF6 pair catalyzed mono ubiquitination of TAGLN. We then identified the ubiquitination sites of TAGLN to be on K89 or K108 residues and demonstrated that ubiquitination of TAGLN on K89/K108 are important for TRAF6-mediated proteasomal degradation. Furthermore, we investigated the function of TAGLN in prostate cancer cells. We found that ablation of TAGLN promoted prostate cancer cell proliferation and suppressed their migration via activation of NF-κB and Myc signaling pathways. Overall, our study provided new insights into the mechanisms underlying TAGLN expression and activity in prostate cancer. IMPLICATIONS: E3 ligase TRAF6 mediate mono-ubiquitination and degradation of TAGLN, which leads to activation of NF-κB and Myc signaling pathways in prostate cancer cells.

Nucleotide variation in histone H2BL drives crossalk of histone modification and promotes tumour cell proliferation by upregulating c-Myc

Gene mutations play important roles in tumour development. In this study, we identified a functional histone H2B mutation H2BL-T11C, causing an amino acid variation from Leu to Pro (L3P, H2BL-L3P). Cells overexpressing H2BL-L3P showed stronger proliferation, colony formation, tumourigenic abilities, and a different cell cycle distribution. Meanwhile, the c-Myc expression was elevated as evident by RNA-seq. We further revealed that an H2BK5ac-H2BK120ubi crosstalk which regulates gene transcription. Moreover, EdU staining demonstrated an important role of c-Myc in accelerating cell cycle progression through the G1/S checkpoint, while treatment with 10058-F4, an inhibitor of the c-Myc/MAX interaction, alleviated the abnormal cell proliferation and cell cycle distribution in vitro and partially inhibited tumour growth in vivo. The mutation of amino acid L3P is associated with tumour progression, suggesting patients carrying this SNP may have higher risk of tumour development.

Taking the Myc out of cancer: toward therapeutic strategies to directly inhibit c-Myc

c-Myc is a transcription factor that is constitutively and aberrantly expressed in over 70% of human cancers. Its direct inhibition has been shown to trigger rapid tumor regression in mice with only mild and fully reversible side effects, suggesting this to be a viable therapeutic strategy. Here we reassess the challenges of directly targeting c-Myc, evaluate lessons learned from current inhibitors, and explore how future strategies such as miniaturisation of Omomyc and targeting E-box binding could facilitate translation of c-Myc inhibitors into the clinic.

NF-κB-dependent Mechanism of Action of c-Myc Inhibitor 10058-F4: Highlighting a Promising Effect of c-Myc Inhibition in Leukemia Cells, Irrespective of p53 Status

Due to the frequent contribution in the pathogenesis of different human malignancies, c-Myc is among those transcription factors that are believed to be pharmacologically targeted for cancer therapeutic approaches. In the present study, we examined the anti-leukemic effect of a well-known c-Myc inhibitor 10058-F4 on a panel of hematologic malignant cells harboring either mutant or wild-type p53. Notably, we found that the suppression of c-Myc was coupled with the reduction in the survival of all the tested leukemic cells; however, as far as we are aware, this study suggests for the first time that the cytotoxic effect of 10058-F4 was not significantly affected by the molecular status of p53. Delving into the molecular mechanisms of the inhibitor in the most sensitive cell line revealed that 10058-F4 could induce apoptotic cell death in mutant p53-expressing NB4 cells through the suppression of NF-κB pathway coupled with a significant induction of intracellular reactive oxygen species (ROS). In addition, we found that the anti-leukemic effect of 10058-F4 was overshadowed, at least partially, through the compensatory activation of the PI3K signaling pathway; highlighting a plausible attenuating role of this axis on 10058-F4 cytotoxicity. In conclusion, the results of the present study shed light on the favorable anti-leukemic effect of 10058-F4, especially in combination with PI3K inhibitors in acute promyelocytic leukemia; however, further investigations should be accomplished to determine the efficacy of the inhibitor, either as a single agent or in a combined-modal strategy, in leukemia treatment.

Neuroblastoma-targeted nanoparticles and novel nanotechnology-based treatment methods

Neuroblastoma is a complicated pediatric tumor, originating from the neural crest, which is the most prevalent in adrenal glands, but may rarely be seen in some other tissues as well. Studies are focused on developing new strategies through novel chemo- and immuno-therapeutic drug targets. Different types of oncogenes such as MYCN, tumor suppressor genes such as p53, and some structural genes such as vascular endothelial growth factor are considered as targets for neuroblastoma therapy. The individual expression patterns in NB cells make them appropriate for this purpose. The combined effect of nano-drug delivery systems and specific drug targets will result in lower systemic side effects, prolonged therapeutic effects, and improvements in the pharmacokinetic properties of the drugs. Some of these novel drug delivery systems with a focus on liposomes as carriers are also discussed. In this review, genes and protein products that are beneficial as drug targets in the treatment of neuroblastoma have been discussed.

Emerging roles and the regulation of aerobic glycolysis in hepatocellular carcinoma

Liver cancer has become the sixth most diagnosed cancer and the fourth leading cause of cancer death worldwide. Hepatocellular carcinoma (HCC) is responsible for up to 75–85% of primary liver cancers, and sorafenib is the first targeted drug for advanced HCC treatment. However, sorafenib resistance is common because of the resultant enhancement of aerobic glycolysis and other molecular mechanisms. Aerobic glycolysis was firstly found in HCC, acts as a hallmark of liver cancer and is responsible for the regulation of proliferation, immune evasion, invasion, metastasis, angiogenesis, and drug resistance in HCC. The three rate-limiting enzymes in the glycolytic pathway, including hexokinase 2 (HK2), phosphofructokinase 1 (PFK1), and pyruvate kinases type M2 (PKM2) play an important role in the regulation of aerobic glycolysis in HCC and can be regulated by many mechanisms, such as the AMPK, PI3K/Akt pathway, HIF-1α, c-Myc and noncoding RNAs. Because of the importance of aerobic glycolysis in the progression of HCC, targeting key factors in its pathway such as the inhibition of HK2, PFK or PKM2, represent potential new therapeutic approaches for the treatment of HCC.

Assessment and Management of Platinum-Related Ototoxicity in Children Treated for Cancer

Platinum compounds are a group of chemotherapeutic agents included in many pediatric and adult oncologic treatment protocols. The main platinum compounds are cisplatin, carboplatin, and oxaliplatin. Their use in clinical practice has greatly improved long-term survival of pediatric patients, but they also cause some toxic effects: ototoxicity, myelosuppression, nephrotoxicity, and neurotoxicity. Hearing damage is one of the main toxic effects of platinum compounds, and it derives from the degeneration of hair cells of the ear, which, not having self-renewal capacity, cannot reconstitute themselves. Hearing loss from platinum exposure is typically bilateral, sensorineural, and permanent, and it is caused by the same mechanisms with which platinum acts on neoplastic cells. According to available data from the literature, the optimal timing for the audiological test during and after treatment with platinum compounds is not well defined. Moreover, no substances capable of preventing the onset of hearing loss have been identified.

Myc is a prognostic biomarker and potential therapeutic target in osteosarcoma

Background

Over the past four decades, outcomes for osteosarcoma patients have plateaued as there have been few emerging therapies showing clinical results. Thus, the identification of novel biomarkers and therapeutic strategies are urgently needed to address these primary obstacles in patient care. Although the Myc-oncogene has known roles in oncogenesis and cancer cell growth, its expression and function in osteosarcoma are largely unknown.

Methods

Expression of Myc was determined by Western blotting of osteosarcoma cell lines and patient tissues, and by immunohistochemistry of a unique osteosarcoma tissue microarray (TMA) constructed from 70 patient samples with extensive follow-up data. Myc specific siRNA and inhibitor 10058-F4 were applied to examine the effect of Myc inhibition on osteosarcoma cell proliferation. The clonogenicity and migration activity was determined by clonogenic and wound-healing assays. A mimic in vivo assay, three-dimensional (3D) cell culture model, was performed to further validate the effect of Myc inhibition on osteosarcoma cell tumorigenic markers.

Results

Myc was significantly overexpressed in human osteosarcoma cell lines compared with normal human osteoblasts, and also highly expressed in fresh osteosarcoma tissues. Higher Myc expression correlated significantly with metastasis and poor prognosis. Through the addition of Myc specific siRNA and inhibitor, we significantly reduced Myc protein expression, resulting in decreased osteosarcoma cell proliferation. Inhibition of Myc also suppressed the migration, clonogenicity, and spheroid growth of osteosarcoma cells.

Conclusion

Our results support Myc as an emerging prognostic biomarker and therapeutic target in osteosarcoma therapy.

Effect of CIP2A and its mechanism of action in the malignant biological behavior of colorectal cancer

Background

Increasing evidence has revealed a close correlation between cancerous inhibitor of protein phosphatase 2A (CIP2A) and cancer progression. CIP2A has been shown to participate in diverse biological processes, such as development, tumorigenic transformation and chemoresistance. However, the functions of CIP2A in colorectal cancer (CRC) and its underlying mechanisms of action are not yet completely understood. The purpose of this study was to explore its clinical significance, function and relevant pathways in CRC.

Methods

Quantitative RT-PCR (qRT-PCR), immunohistochemistry (IHC), western blotting and enzyme-linked immunosorbent assay (ELISA) were used to identify the expression of CIP2A in CRC tissues, sera and CRC cell lines. The association between the expressions of CIP2A and patient survival was analyzed using the Kaplan-Meier curves. Additionally, the functional role of CIP2A in the cell lines was identified through small interfering RNA (siRNA)-mediated depletion of the protein followed by analyses of proliferation and xenograft growth in vivo using short hairpin (sh) RNAs. Effects of the C-myc inhibitor 10,058-F4 on the expressions of C-myc, and CIP2A in CRC cell lines and its potential mechanisms of action were investigated. Finally, the potential molecular pathways associated with CIP2A were screened using the phosphokinase array and identified through western blotting.

Results

CIP2A mRNA and protein levels were upregulated in CRC tissues compared to those of the corresponding normal tissues. It can be used as an independent prognostic indicator to determine overall survival (OS) and disease-free survival (DFS). Depletion of CIP2A substantially suppressed the growth of CRC cells and colony formation in vitro, and inhibited the growth of xenograft tumors in vivo. Additionally, the levels of CIP2A in the sera of patients with CRC were higher than those of the control subjects. Multivariate analyses revealed that the levels of CIP2A in the sera were not independent prognostic indicators in patients with CRC. Moreover, 10,058-F4 could effectively inhibit the growth of CRC cells in vitro, which could be correlated with an inhibition in the expressions of C-myc, CIP2A and its downstream regulatory anti-apoptotic proteins. Furthermore, the Human Phosphokinase Antibody Array was used to gain insights into the CIP2A-dependent intermediary signaling pathways. The results revealed that several signaling pathways were affected and the protein levels of p-p53 (S392), p-STAT5a (Y694), Cyclin D1, p-ERK1/2 and p-AKT (T308) had decreased in CIP2A-shRNA group based on the results of the western blot analysis.

Conclusions

CIP2A could promote the development of CRC cells and predict poor prognosis in patients with CRC, suggesting that it may serve as a potential prognostic marker and therapeutic target against CRC.

Ototoxicity after platinum-based chemotherapy in the treatment of melanotic neuroectodermal tumour of infancy

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare infantile tumor that originates from mesenchymal-neuroectodermal cells, the treatment of which uses platinum derivatives that can affect hearing loss. The present study evaluated the long-term effects of ototoxicity following chemotherapy with cisplatin, vincristine, cyclophosphamide, teniposide and adriamycin in a 10-year-old patient after surgical removal of a MNTI tumor at the age of 8 months. Audiometric tests (high-frequency tonal audiometry, speech audiometry, speech acoustics, tympanometry and absorbance measurements) were performed during a 10-year follow-up after receiving chemotherapy. Hearing disorders in the high-frequency range (6,000 to 16,000 Hz range) were demonstrated for both ears, indicating that these may be the long-term effects of chemotherapy with use of platinum compounds during the treatment of infants.

Tumor-suppressive function and mechanism of HOXB13 in right-sided colon cancer

Right-sided colon cancer (RCC) and left-sided colon cancer (LCC) differ in their clinical and molecular features. An investigation of differentially expressed genes (DEGs) between RCC and LCC could contribute to targeted therapy for colon cancer, especially RCC, which has a poor prognosis. Here, we identified HOXB13, which was significantly less expressed in RCC than in LCC and associated with prognosis in RCC, by using 5 datasets from the Gene Expression Omnibus (GEO). Tissue sample analysis showed that HOXB13 was differentially expressed between normal and only RCC tumor tissues. HOXB13 inhibited colon cancer cell proliferation and induced apoptosis both in vitro and in vivo. Furthermore, we found that HOXB13 might be regulated by DNMT3B and suppress C-myc expression to exert antitumor effects via β-catenin/TCF4 signals in RCC. In conclusion, the current study is the first to demonstrate that HOXB13 has a tumor-suppressive effect in RCC. High expression levels of HOXB13 are associated with prolonged overall survival in patients with RCC. The DNMT3B-HOXB13-C-myc signaling axis might be a molecular target for the treatment of RCC.

Physiologically relevant orthogonal assays for the discovery of small-molecule modulators of WIP1 phosphatase in high-throughput screens

WT P53-Induced Phosphatase 1 (WIP1) is a member of the magnesium-dependent serine/threonine protein phosphatase (PPM) family and is induced by P53 in response to DNA damage. In several human cancers, the WIP1 protein is overexpressed, which is generally associated with a worse prognosis. Although WIP1 is an attractive therapeutic target, no potent, selective, and bioactive small-molecule modulator with favorable pharmacokinetics has been reported. Phosphatase enzymes are among the most challenging targets for small molecules because of the difficulty of achieving both modulator selectivity and bioavailability. Another major obstacle has been the availability of robust and physiologically relevant phosphatase assays that are suitable for high-throughput screening. Here, we describe orthogonal biochemical WIP1 activity assays that utilize phosphopeptides from native WIP1 substrates. We optimized an MS assay to quantify the enzymatically dephosphorylated peptide reaction product in a 384-well format. Additionally, a red-shifted fluorescence assay was optimized in a 1,536-well format to enable real-time WIP1 activity measurements through the detection of the orthogonal reaction product, P_i. We validated these two optimized assays by quantitative high-throughput screening against the National Center for Advancing Translational Sciences (NCATS) Pharmaceutical Collection and used secondary assays to confirm and evaluate inhibitors identified in the primary screen. Five inhibitors were further tested with an orthogonal WIP1 activity assay and surface plasmon resonance binding studies. Our results validate the application of miniaturized physiologically relevant and orthogonal WIP1 activity assays to discover small-molecule modulators from high-throughput screens.

Emerging Roles of C-Myc in Cancer Stem Cell-Related Signaling and Resistance to Cancer Chemotherapy: A Potential Therapeutic Target Against Colorectal Cancer

Myc is a nuclear transcription factor that mainly regulates cell growth, cell cycle, metabolism, and survival. Myc family proteins contain c-Myc, n-Myc, and l-Myc. Among them, c-Myc can become a promising therapeutic target molecule in cancer. Cancer stem cells (CSCs) are known to be responsible for the therapeutic resistance. In the previous study, we demonstrated that c-Myc mediates drug resistance of colorectal CSCs using a patient-derived primary three-dimensional (3D) organoid culture. In this review, we mainly focus on the roles of c-Myc-related signaling in the regulation of CSCs, chemotherapy resistance, and colorectal cancer organoids. Finally, we introduce the various types of c-Myc inhibitors and propose the possibility of c-Myc as a therapeutic target against colorectal cancer.

The peculiarities of cancer cell metabolism: A route to metastasization and a target for therapy

The last decade has witnessed the peculiarities of metabolic reprogramming in tumour onset and progression, and their relevance in cancer therapy. Also, it has been indicated that the metastatic process may depend on the metabolic rewiring and adaptation of cancer cells to the pressure of tumour microenvironment and limiting nutrient availability. The present review gatherers the existent knowledge on the influence of tumour microenvironment and metabolic routes driving metastasis. A focus will be given to glycolysis, fatty acid metabolism, glutaminolysis, and amino acid handling. In addition, the role of metabolic waste driving metastasization will be explored. Finally, we discuss the status of cancer treatment approaches targeting metabolism. This knowledge revision will highlight the critical metabolic targets in metastasis and the chemicals already used in preclinical studies and clinical trials, providing clues that would be further exploited in medicinal chemistry research.

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

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

Lipid nanoparticles that deliver IL-12 messenger RNA suppress tumorigenesis in MYC oncogene-driven hepatocellular carcinoma

Interleukin-12 (IL-12) is a promising candidate for cancer immunotherapy because of its ability to activate a number of host immune subsets that recognize and destroy cancer cells. We found that human hepatocellular carcinoma (HCC) patients with higher than median levels of IL-12 have significantly favorable clinical outcomes. Here, we report that a messenger RNA (mRNA) lipid nanoparticle delivering IL-12 (IL-12-LNP) slows down the progression of MYC oncogene-driven HCC. IL-12-LNP was well distributed within the HCC tumor and was not associated with significant animal toxicity. Treatment with IL-12-LNP significantly reduced liver tumor burden measured by dynamic magnetic resonance imaging (MRI), and increased survival of MYC-induced HCC transgenic mice in comparison to control mice. Importantly, IL-12-LNP exhibited no effect on transgenic MYC levels confirming that its therapeutic efficacy was not related to the downregulation of a driver oncogene. IL-12-LNP elicited marked infiltration of activated CD44⁺ CD3⁺ CD4⁺ T helper cells into the tumor, and increased the production of Interferon γ (IFNγ). Collectively, our findings suggest that IL-12-LNP administration may be an effective immunotherapy against HCC.

Identification of a novel c-Myc inhibitor with antitumor effects on multiple myeloma cells

Increasing evidence shows that c-Myc oncoprotein is tightly associated with multiple myeloma (MM) progression. Herein, we identified compound 7594-0035, which is a novel inhibitor that specifically targets c-Myc. It was identified from the ChemDiv compound database by molecular docking-based, high-throughput virtual screening. Compound 7594-0035 inhibited MM cell proliferation in vitro, induced cell cycle G₂-phase arrest, and triggered MM cell death by disturbing the stability of c-Myc protein. Additionally, we also found that compound 7594-0035 overcame bortezomib (BTZ) drug resistance and increased the killing effect on MM cells in combination with BTZ. The severe combined immune deficiency (SCID) mouse xenograft model revealed that compound 7594-0035 partially decreased the primary tumor growth of Roswell Park Memorial Institute (RPMI)-8226 cells in vivo The novel small molecular compound 7594-0035 described in the present study that targets c-Myc protein is likely to be a promising therapeutic agent for relapsed/refractory MM.

miR-137 mediates the functional link between c-Myc and EZH2 that regulates cisplatin resistance in ovarian cancer

Platinum drugs are used in first-line to treat ovarian cancer, but most of the patients eventually generate resistance after treatment with these drugs. Although both c-Myc and EZH2 have been implicated in regulating cisplatin resistance in ovarian cancer, the interplay between these two regulators is poorly understood. Using RNA sequence analysis (RNA-seq), for the first time we find that miR-137 level is extremely low in cisplatin resistant ovarian cancer cells, correlating with higher levels of c-Myc and EZH2 expression. Further analyses indicate that in resistant cells c-Myc enhances the expression of EZH2 by directly suppressing miR-137 that targets EZH2 mRNA, and increased expression of EZH2 activates cellular survival pathways, resulting in the resistance to cisplatin. Inhibition of c-Myc-miR-137-EZH2 pathway re-sensitizes resistant cells to cisplatin. Both in vivo and in vitro analyses indicate that cisplatin treatment activates c-Myc-miR-137-EZH2 pathway. Importantly, elevated c-Myc-miR-137-EZH2 pathway in resistant cells is sustained by dual oxidase maturation factor 1 (DUOXA1)-mediated production of reactive oxygen species (ROS). Significantly, clinical studies further confirm the activated c-Myc-miR-137-EZH2 pathway in platinum drug-resistant or recurrent ovarian cancer patients. Thus, our studies elucidate a novel role of miR-137 in regulating c-Myc-EZH2 axis that is crucial to the regulation of cisplatin resistance in ovarian cancer.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

Recent developments with rhodanine as a scaffold for drug discovery

INTRODUCTION

Rhodanines, as one of the 4-thiazolidinones subtypes, are recognized as privileged heterocycles in medicinal chemistry. The main achievements include the development of drug-like molecules with numerous biological activities as well as approved drugs. Among rhodanines, 5-ene-rhodanines are of special interest, and are often claimed as pan assay interference compounds due to Michael acceptor functionality. Areas covered: Herein, the synthetic protocols for rhodanines and their transformation are reviewed. Biological activity is briefly discussed as well as biotargets, mode of actions and optimization directions. Furthermore, the utilization of 5-ene-rhodanines in Michael additions are discussed while both pro and contra arguments have been outlined within medicinal chemistry application. Expert opinion: Rhodanines remain privileged heterocycles in drug discovery. They are accessible building blocks for optimization and transformation into related heterocycles, simplified analogues and fused heterocycles with a thiazolidine framework. Michael acceptor functionality, as well as the thesis about low selectivity towards biotargets of rhodanines, must be confirmed experimentally and it cannot be based on just the presence of conjugated α,β-unsaturated carbonyl. Moreover, the positive aspects of Michael acceptors must be considered as well as their multitarget properties. New criteria for target affinity must be found. In conclusion, rhodanines are generally not problematic per se.

RLIM suppresses hepatocellular carcinogenesis by up-regulating p15 and p21

Hepatocellular carcinogenesis results from dysregulation of oncogenes and tumor suppressors that influence cellular proliferation, differentiation and apoptosis. p15 and p21 are cyclin-dependent kinase inhibitors, which arrest cell proliferation and serve as critical tumor suppressors. Here we report that the E3 ubiquitin ligase RLIM expression is downregulated in hepatocellular carcinoma patients, and correlated with p15 and p21 expression in clinical progression. In addition, we showed that RLIM overexpression suppresses the cell growth and arrests cell cycle progression of hepatocellular carcinoma. Mechanistically, we found that RLIM directly binds to MIZ1, disrupting the interaction between c-MYC and MIZ1, and enhancing p15 and p21 transcription. Our results demonstrate that RLIM is an important suppressor in hepatocellular carcinogenesis.

De novo MYC addiction as an adaptive response of cancer cells to CDK4/6 inhibition

Cyclin‐dependent kinases (CDK) are rational cancer therapeutic targets fraught with the development of acquired resistance by tumor cells. Through metabolic and transcriptomic analyses, we show that the inhibition of CDK4/6 leads to a metabolic reprogramming associated with gene networks orchestrated by the MYC transcription factor. Upon inhibition of CDK4/6, an accumulation of MYC protein ensues which explains an increased glutamine metabolism, activation of the mTOR pathway and blunting of HIF‐1α‐mediated responses to hypoxia. These MYC‐driven adaptations to CDK4/6 inhibition render cancer cells highly sensitive to inhibitors of MYC, glutaminase or mTOR and to hypoxia, demonstrating that metabolic adaptations to antiproliferative drugs unveil new vulnerabilities that can be exploited to overcome acquired drug tolerance and resistance by cancer cells.

miR-181d and c-myc-mediated inhibition of CRY2 and FBXL3 reprograms metabolism in colorectal cancer

Colorectal cancer (CRC) is the second major cause of tumor-related deaths. MicroRNAs (miRNAs) have pivotal roles in CRC progression. Here, we describe the effect of miR-181d on CRC cell metabolism and underlying molecular mechanism. Our data firmly demonstrated that knockdown of miR-181d suppressed CRC cell proliferation, migration, and invasion by impairing glycolysis. Mechanistically, miR-181d stabilized c-myc through directly targeting the 3'-UTRs of CRY2 and FBXL3, which subsequently increased the glucose consumption and the lactate production. Inhibition of c-myc via siRNA or small molecular inhibitor abolished the oncogenic effects of miR-181d on the growth and metastasis of CRC cells. Furthermore, c-myc/HDAC3 transcriptional suppressor complex was found to co-localize on the CRY2 and FBXL3 promoters, epigenetically inhibit their transcription, and finally induce their downregulation in CRC cells. In addition, miR-181d expression could be directly induced by an activation of c-myc signaling. Together, our data indicate an oncogenic role of miR-181d in CRC by promoting glycolysis, and miR-181d/CRY2/FBXL3/c-myc feedback loop might be a therapeutic target for patients with CRC.

Regulation of glucose uptake in lymphoma cell lines by c-MYC- and PI3K-dependent signaling pathways and impact of glycolytic pathways on cell viability

BACKGROUND

Changes in glucose and energy metabolism contribute to the altered phenotype of cancer cells and are the basis for positron emission tomography with ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) to visualize tumors in vivo. The molecular background of the enhanced glucose uptake and its regulation in lymphoma cells is not fully clarified and may provide new possibilities to reverse the altered metabolism. Thus in this study we investigated regulation of glucose uptake by different signaling pathways. Furthermore, the effect of the glucose analog 2-deoxy-D-glucose (2-DG) alone and in combination with other inhibitors on cell survival was studied.

METHODS

An FDG uptake assay was established and uptake of FDG by lymphoma cells was determined after incubation with inhibitors of the c-MYC and the PI3K signalling pathways that are known to be activated in lymphoma cells and able to regulate glucose metabolism. Inhibitors of MAPK signalling pathways whose role in altered metabolism is still unclear were also investigated. Expression of mRNAs of the glucose transporter 1 (GLUT1), hexokinase 2 (HK2), glucose-6-phosphatase (G6Pase) and lactate dehydrogenase A (LDHA) and of the glucose metabolism-regulating micro RNAs (miRNA) miR21, -23a, -133a, -133b, -138-1 and -143 was determined by RT-PCR. Cell viability was analysed by MTT assay.

RESULTS

Treatment with the c-MYC inhibitor 10058-F4 and inhibitors of the PI3K/mTOR pathway diminished uptake of FDG in all three cell lines, while inhibition of MAPK pathways had no effect on glucose uptake. Expression of glycolysis-related genes and miRNAs were diminished, although to a variable degree in the three cell lines. The c-MYC inhibitor, the PI3K inhibitor LY294002, the mTOR inhibitor Rapamycin and 2-DG all diminished the number of viable cells. Interestingly, in combination with 2-DG, the c-MYC inhibitor, LY294002 and the p38 MAPK inhibitor SB203580 had synergistic effects on cell viability in all three cell lines.

CONCLUSIONS

c-MYC- and PI3K/mTOR-inhibitors decreased viability of the lymphoma cells and led to decreased glucose uptake, expression of glycolysis-associated genes, and glucose metabolism-regulating miRNAs. Inhibition of HK by 2-DG reduced cell numbers as a single agent and synergistically with inhibitors of other intracellular pathways. Thus, targeted inhibition of the pathways investigated here could be a strategy to suppress the glycolytic phenotype of lymphoma cells and reduce proliferation.

The Dual Roles of MYC in Genomic Instability and Cancer Chemoresistance

Cancer is associated with genomic instability and aging. Genomic instability stimulates tumorigenesis, whereas deregulation of oncogenes accelerates DNA replication and increases genomic instability. It is therefore reasonable to assume a positive feedback loop between genomic instability and oncogenic stress. Consistent with this premise, overexpression of the MYC transcription factor increases the phosphorylation of serine 139 in histone H2AX (member X of the core histone H2A family), which forms so-called γH2AX, the most widely recognized surrogate biomarker of double-stranded DNA breaks (DSBs). Paradoxically, oncogenic MYC can also promote the resistance of cancer cells to chemotherapeutic DNA-damaging agents such as cisplatin, clearly implying an antagonistic role of MYC in genomic instability. In this review, we summarize the underlying mechanisms of the conflicting functions of MYC in genomic instability and discuss when and how the oncoprotein exerts the contradictory roles in induction of DSBs and protection of cancer-cell genomes.

YPC-21661 and YPC-22026, novel small molecules, inhibit ZNF143 activity in vitro and in vivo

Zinc‐finger protein 143 (ZNF143) is a transcription factor that is involved in anticancer drug resistance and cancer cell survival. In the present study, we identified a novel small molecule N‐(5‐bromo‐2‐methoxyphenyl)‐3‐(pyridine‐3‐yl) propiolamide (YPC‐21661) that inhibited ZNF143 promoter activity and down‐regulated the expression of the ZNF143‐regulated genes, RAD51, PLK1, and Survivin, by inhibiting the binding of ZNF143 to DNA. In addition, YPC‐21661 was cytotoxic and induced apoptosis in the human colon cancer cell line, HCT116 and human prostate cancer cell line, PC‐3. 2‐(pyridine‐3‐ylethynyl)‐5‐(2‐(trifluoromethoxy)phenyl)‐1,3,4‐oxadiazole (YPC‐22026), a metabolically stable derivative of YPC‐21661, induced tumor regression accompanied by the suppression of ZNF143‐regulated genes in a mouse xenograft model. The present study revealed that the inhibition of ZNF143 activity by small molecules induced tumor regression in vitro and in vivo; therefore, ZNF143 is a promising target of cancer therapeutics.

c-MYC-Making Liver Sick: Role of c-MYC in Hepatic Cell Function, Homeostasis and Disease

Over 35 years ago, c-MYC, a highly pleiotropic transcription factor that regulates hepatic cell function, was identified. In recent years, a considerable increment in the number of publications has significantly shifted the way that the c-MYC function is perceived. Overexpression of c-MYC alters a wide range of roles including cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion and differentiation. The purpose of this review is to broaden the understanding of the general functions of c-MYC, to focus on c-MYC-driven pathogenesis in the liver, explain its mode of action under basal conditions and during disease, and discuss efforts to target c-MYC as a plausible therapy for liver disease.

E3 ubiquitin ligase FBW7α inhibits cholangiocarcinoma cell proliferation by downregulating c-Myc and cyclin E

FBW7 (F-box and WD repeat domain-containing 7), also known as CDC4, AGO and SEL10, is the substrate recognition component of an evolutionary conserved SCF (complex of SKP1, CUL1 and F-box protein)-type E3 ubiquitin ligase. It is a recognized tumor suppressor because it targets multiple oncoproteins for ubiquitination-mediated destruction and its mutations are frequently identified in a variety of human malignancies. However, the function of FBW7 in proliferation of cholangiocarcinoma (CCA) remains unknown. We found that overexpression of FBW7α induced CCA cell arrest in G1 phase of cell cycle and inhibited cell proliferation in vitro and CCA xenograft tumor growth, suggesting that FBW7α is a tumor suppressor in CCA progression. Overxpression of FBW7α resulted in the protein degradation of its substrates such as c-Myc and cyclin E which promote CCA cell proliferation. Restoration of the expression of c-Myc, but not cyclin E, rescued the proliferation of FBW7α-overexpression CCA cells. These results suggest that FBW7α plays an essential inhibitory role in CCA progression, indicating that targeting FBW7α substrate c-Myc may be a potential strategy for CCA treatment.

Induction of Transcriptional Gene Silencing by Expression of shRNA Directed to c-Myc P2 Promoter in Hepatocellular Carcinoma by Tissue-Specific Virosomal Delivery

Double-stranded RNA-mediated transcriptional gene silencing (TGS) has shown promising results over posttranscriptional gene silencing (PTGS) due to its long term and heritable nature. Various research groups have shed light on different mechanisms by which TGS operate. Some of these include histone modification, DNA methylation, or restriction of RNA polymerase binding onto the target gene's promoter. This serves as an added advantage since permanent c-Myc inactivation is critical for suppressing hepatocellular carcinoma (HCC). Inability to target cancer cells specifically, without affecting the normal cells, has been one of the biggest drawbacks of an effective cancer therapy. Therefore, we aimed to overcome this barrier by first generating tumor-specific transcriptional units expressing TGS inducing shRNAs against c-Myc's P2 promoter only in neoplastic liver cells. Secondly, we coupled this TGS inducing system with Sendai fusion virosomes for liver-specific delivery to minimize nonspecific side effects in vitro.

Krüppel-like factor 2 promotes cell proliferation in hepatocellular carcinoma through up-regulation of c-myc

Members of krüppel-like factor family have been shown to play critical roles in the development, metabolism and tumorigenesis. Our previous study demonstrated that up-regulationupregulation of KLF2 in livers from obese mice could promote hepatosteatosis. However, little is known about its effects in hepatocellular carcinogenesis. In the present study, we found that mRNA and protein expression of KLF2 was increased in primary HCC, when compared with that in adjacent normal liver. In vitro studies further showed that enforced overexpression of KLF2 expression enhanced, while its knockdown inhibited cell proliferation and invasion. At the molecular level, c-myc was a direct transcriptional target of KLF2 and a KLF2-binding site in the c-myc promoter bound specifically to KLF2 protein. Indeed, ablation of c-myc largely attenuated the proliferative roles of KLF2 in HCC cells. Therefore, our data highlight an important role for KLF2/c-myc pathway in HCC development and progression.