Knockdown of c-Myc inhibits cell proliferation by negatively regulating the Cdk/Rb/E2F pathway in nasopharyngeal carcinoma cells

Analysis of Promoter Methylation of the Bovine FOXO1 Gene and Its Effect on Proliferation and Differentiation of Myoblasts

This study aimed to explore the regulatory role of FOXO1 promoter methylation on its transcriptional level and unravel the effect of FOXO1 on the proliferation and differentiation of bovine myoblasts. Bisulfite sequencing polymerase chain reaction (BSP) and real-time quantitative PCR were performed to determine the methylation status and transcript levels of the FOXO1 promoter region at different growth stages. BSP results showed that the methylation level in the calf bovine (CB) group was significantly higher than that in the adult bovine (AB) group (p < 0.05). On the other hand, qRT-PCR results indicated that the mRNA expression level in the AB group was significantly higher than that in the CB group (p < 0.05), suggesting a significant decrease in gene expression at high levels of DNA methylation. CCK-8 and flow cytometry were applied to determine the effect of silencing the FOXO1 gene on the proliferation of bovine myoblasts. Furthermore, qRT-PCR and Western blot were conducted to analyze the expression of genes associated with the proliferation and differentiation of bovine myoblasts. Results from CCK-8 revealed that the short hairpin FOXO1 (shFOXO1) group significantly promoted the proliferation of myoblasts compared to the short-hairpin negative control (shNC) group (p < 0.05). Flow cytometry results showed a significant decrease in the number of the G1 phase cells (p < 0.05) and a significant increase in the number of the S phase cells (p < 0.05) in the shFOXO1 group compared to the shNC group. In addition, the expression of key genes for myoblast proliferation (CDK2, PCNA, and CCND1) and differentiation (MYOG, MYOD, and MYHC) was significantly increased at both mRNA and protein levels (p < 0.05). In summary, this study has demonstrated that FOXO1 transcription is regulated by methylation in the promoter region and that silencing FOXO1 promotes the proliferation and differentiation of bovine myoblasts. Overall, our findings lay the foundation for further studies on the regulatory role of epigenetics in the development of bovine myoblasts.

Curcumin arrests G-quadruplex in the nuclear hyper-sensitive III1 element of c-MYC oncogene leading to apoptosis in metastatic breast cancer cells

c-MYC is deregulated in triple negative breast cancer (TNBC) pointing to be a promising biomarker for breast cancer treatment. Precise level of MYC expression is important in the control of cellular growth and proliferation. Designing of c-MYC-targeted antidotes to restore its basal level of cellular expression holds an optimistic approach towards anti-cancer treatment. MYC transcription is dominantly controlled by Nuclear Hypersensitive Element III-1 (NHE_III1) upstream of the promoter region possessing G-Quadruplex silencer element (Pu-27). We have investigated the selective binding-interaction profile of a natural phytophenolic compound Curcumin with native MYC G-quadruplex by conducting an array of biophysical experiments and in silico based Molecular Docking and Molecular Dynamic (MDs) simulation studies. Curcumin possesses immense anti-cancerous properties. We have observed significantly increased stability of MYC-G Quadruplex and thermodynamic spontaneity of Curcumin-MYC GQ binding with negative ΔG value. Transcription of MYC is tightly regulated by a complex mechanism involving promoters, enhancers and multiple transcription factors. We have used Curcumin as a model drug to understand the innate mechanism of controlling deregulated MYC back to its basal expression level. We have checked MYC-expression at transcriptional and translational level and proceeded for Chromatin Immuno-Precipitation assay (ChIP) to study the occupancy level of SP1, Heterogeneous nuclear ribonucleoprotein K (hnRNPK), Nucleoside Diphosphate Kinase 2 (NM23-H2) and Nucleolin at NHE_III1 upon Curcumin treatment of MDA-MB-231 cells. We have concluded that Curcumin binding tends to drive the equilibrium towards stable G-quadruplex formation repressing MYC back to its threshold-level. On retrospection of the synergistic effect of upregulated c-MYC and BCL-2 in cancer, we have also reported a new pathway [MYC-E2F-1-BCL-2-axis] through which Curcumin trigger apoptosis in cancer cells.Communicated by Ramaswamy H. Sarma.

The pro-tumorigenic activity of p38γ overexpression in nasopharyngeal carcinoma

It is urgent to identify and validate biomarkers for early diagnosis and efficient treatment of nasopharyngeal carcinoma (NPC). Recent studies have proposed p38 gamma (p38γ) as a cyclin-dependent kinase (CDK)-like kinase that phosphorylates retinoblastoma (Rb) to promote cyclins expression and tumorigenesis. Here the Gene Expression Profiling Interactive Analysis (GEPIA) database and results from the local NPC tissues demonstrate that p38γ is significantly upregulated in NPC tissues, correlating with poor overall survival. Furthermore, p38γ mRNA and protein expression is elevated in established NPC cell lines (CNE-1 HONE-1 and CNE-2) and primary human NPC cells, but low expression detected in human nasal epithelial cells. In established and primary NPC cells, p38γ depletion, using the shRNA strategy or the CRISPR/Cas9 gene-editing method, largely inhibited cell growth, proliferation and migration, and induced significant apoptosis activation. Contrarily, ectopic p38γ overexpression exerted opposite activity and promoted NPC cell proliferation and migration. Retinoblastoma (Rb) phosphorylation and cyclin E1/A expression were decreased in NPC cells with p38γ silencing or knockout, but increased after p38γ overexpression. Moreover, mitochondrial subcellular p38γ localization was detected in NPC cells. Significantly, p38γ depletion disrupted mitochondrial functions, causing mitochondrial depolarization, reactive oxygen species production, oxidative injury and ATP depletion in NPC cells. In vivo, intratumoral injection of adeno-associated virus-packed p38γ shRNA potently inhibited primary human NPC xenograft growth in nude mice. In p38γ shRNA virus-injected NPC xenograft tissues, p38γ expression, Rb phosphorylation, cyclin E1/A expression and ATP levels were dramatically decreased. Taken together, we conclude that p38γ overexpression is required for NPC cell growth, acting as a promising therapeutic target of NPC.

Splicing factor derived circular RNA circCAMSAP1 accelerates nasopharyngeal carcinoma tumorigenesis via a SERPINH1/c-Myc positive feedback loop

Background

Circular RNAs play an important role in tumor genesis and progression, but they have not been sufficiently studied in patients with nasopharyngeal carcinoma (NPC).

Methods

The circular RNA, circCAMSAP1, was screened in NPC cells by RNA sequencing analysis. The expression of circCAMSAP1 in NPC tissues was examined by real-time quantitative polymerase chain reaction (RT-qPCR) and in situ hybridization. Wound-healing, transwell, MTT and flow cytometry assays, and nude mouse tumor models were used to explore the effect of circCAMSAP1 on proliferation and metastasis of NPC in vitro or in vivo. The downstream proteins regulated by circCAMSAP1 were screened using mass spectrometry. The interaction between circCAMSAP1 and the SERPINH1 mRNA was identified using the circular RNA immunoprecipitation method and the luciferase reporter assay. The interaction between SERPINH1 and transcription factor c-Myc was verified through Co-immunoprecipitation (Co-IP) and immunofluorescence. The effect of c-Myc on the generation of circCAMSAP1 was examined through RT-qPCR and chromatin immunoprecipitation. Finally, the splicing factors that promote the production of circCAMSAP1 were explored by RT-qPCR and RNA immunoprecipitation (RIP).

Results

We found that circCAMSAP1 was highly expressed in NPC tissues and promoted NPC proliferation and metastasis. Additionally, circCAMSAP1 promoted SERPINH1 expression through improved SERPINH1 mRNA stability by binding to the 3′-untranslated region (3’UTR) of SERPINH1. Highly expressed SERPINH1 reduced the ubiquitination-degradation rate of c-Myc, causing increased tumorigenesis. Meanwhile, c-Myc, cooperating with splicing factor 10 (SRSF10), could also promote CAMSAP1 pre-mRNA transcription and back-splicing, forming a positive feedback of circCAMSAP1 production, resulting in the proliferation and metastasis of NPC.

Conclusions

Our findings revealed that circCAMSAP1 promotes NPC proliferation and metastasis by binding to the 3’UTR of SERPINH1, suggesting that the positive feedback of circCAMSAP1-SERPINH1-c-Myc may serve as a prognostic biomarker or therapeutic target in patients with NPC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01502-2.

Autoantibody Signatures as a Biomarker Panel for the Detection of Nasopharyngeal Carcinoma

OBJECTIVE

The early symptoms of nasopharyngeal carcinoma (NPC) are not obvious, and it is difficult to make early diagnosis. A case-control study was conducted to identify potential biomarkers and established a diagnosis model for nasopharyngeal carcinoma.

METHODS

Plasma samples of 131 cases of NPC and 132 cases of healthy individuals were incubated with the Ray Biotech Human Lung Cancer IgG Autoantibody Detection Array G1, and signal values were used to develop a risk prediction model for NPC diagnosis.

RESULTS

Of the 30 autoantibodies, high expression of MAGE-A4, NY-ESO-1, HuD, Survivin, IMDH2, Ubiquilin-1, IMP1, PGP9.5, IMP3, C-Myc and low expression of Cyclin B1 were potential biomarkers for NPC diagnosis (p <0.05), among which Survivin, MAGE-A4 and IMP3 shows higher AUC of 0.674, 0.652 and 0.650 respectively, the specificity of them was 89.39% (95% CI: 82.85-94.08%), 90.15% (95% CI: 83.75-94.65%) and 88.64% (81.95-93.50%).The risk probability analysis for NPC diagnosis based on the panel of Cyclin B1, NY-ESO-1, Survivin, and IMP3 displayed the best diagnosis performance with an AUC of 0.779, p (Yi = 1) = 1/(1+EXP[8.316+1.672*CyclinB1-1.152*NY-ESO-1-2.052*Survivin-0.950*IMP3]), the specificity of that was 86.36% (95% CI: 79.31-91.71%).

CONCLUSIONS

Our findings demonstrated that the panel of Cyclin B1, NY-ESO-1, Survivin, and IMP3 has a good performance in the detection of NPC, and all 11 autoantibodies may also have a certain significance for the prognosis of NPC.

The Role of Non-Coding RNAs in the Regulation of the Proto-Oncogene MYC in Different Types of Cancer

Alterations in the expression level of the MYC gene are often found in the cells of various malignant tumors. Overexpressed MYC has been shown to stimulate the main processes of oncogenesis: uncontrolled growth, unlimited cell divisions, avoidance of apoptosis and immune response, changes in cellular metabolism, genomic instability, metastasis, and angiogenesis. Thus, controlling the expression of MYC is considered as an approach for targeted cancer treatment. Since c-Myc is also a crucial regulator of many cellular processes in healthy cells, it is necessary to find ways for selective regulation of MYC expression in tumor cells. Many recent studies have demonstrated that non-coding RNAs play an important role in the regulation of the transcription and translation of this gene and some RNAs directly interact with the c-Myc protein, affecting its stability. In this review, we summarize current data on the regulation of MYC by various non-coding RNAs that can potentially be targeted in specific tumor types.

Glutamine Metabolism in Cancer

Metabolism is a fundamental process for all cellular functions. For decades, there has been growing evidence of a relationship between metabolism and malignant cell proliferation. Unlike normal differentiated cells, cancer cells have reprogrammed metabolism in order to fulfill their energy requirements. These cells display crucial modifications in many metabolic pathways, such as glycolysis and glutaminolysis, which include the tricarboxylic acid (TCA) cycle, the electron transport chain (ETC), and the pentose phosphate pathway (PPP) [1]. Since the discovery of the Warburg effect, it has been shown that the metabolism of cancer cells plays a critical role in cancer survival and growth. More recent research suggests that the involvement of glutamine in cancer metabolism is more significant than previously thought. Glutamine, a nonessential amino acid with both amine and amide functional groups, is the most abundant amino acid circulating in the bloodstream [2]. This chapter discusses the characteristic features of glutamine metabolism in cancers and the therapeutic options to target glutamine metabolism for cancer treatment.

BRD7 Promotes Cell Proliferation and Tumor Growth Through Stabilization of c-Myc in Colorectal Cancer

BRD7 functions as a crucial tumor suppressor in numerous malignancies. However, the effects of BRD7 on colorectal cancer (CRC) progression are still unknown. Here, based on the BRD7 knockout (BRD7^-/-) and BRD7 ^flox/flox (BRD7^+/+) mouse models constructed in our previous work, we established an azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse model. BRD7^+/+ mice were found to be highly susceptible to AOM/DSS-induced colitis-associated CRC, and BRD7 significantly promoted cell proliferation and cell cycle G1/S transition but showed no significant effect on cell apoptosis. Furthermore, BRD7 interacted with c-Myc and stabilized c-Myc by inhibiting its ubiquitin-proteasome-dependent degradation. Moreover, restoring the expression of c-Myc in BRD7-silenced CRC cells restored cell proliferation, cell cycle progression, and tumor growth in vitro and in vivo. In addition, BRD7 and c-Myc were both significantly upregulated in CRC patients, and high expression of these proteins was associated with clinical stage and poor prognosis in CRC patients. Collectively, BRD7 functions as an oncogene and promotes CRC progression by regulating the ubiquitin-proteasome-dependent stabilization of c-Myc protein. Targeting the BRD7/c-Myc axis could be a potential therapeutic strategy for CRC.

c-Myc-induced circ-NOTCH1 promotes aggressive phenotypes of nasopharyngeal carcinoma cells by regulating the miR-34c-5p/c-Myc axis

Nasopharyngeal carcinoma (NPC) is the subclass of head and neck cancer with the highest incidence among otolaryngology malignancies. A growing amount of evidence has proven that circular RNAs (circRNAs) play key roles in the progression of multiple cancers. It has been reported that circ-NOTCH1 is a novel circRNA and functions as an oncogene in gastric cancer, while the regulatory mechanism of circ-NOTCH1 in NPC remains unknown. In the present research, our findings revealed that circ-NOTCH1 was overexpressed in NPC tissues and cells. Circ-NOTCH1 knockdown suppressed NPC cell proliferation, invasion, and migration. Subsequently, we discovered that c-Myc can activate circ-NOTCH1 by binding to the NOTCH1 promoter. c-Myc functioned as a tumor promoter in NPC cells. Mechanistically, circ-NOTCH1 served as a competitive endogenous RNA to modulate c-Myc expression by sponging miR-34c-5p. Additionally, overexpression of c-Myc reversed the circ-NOTCH1 knockdown-mediated inhibition of NPC cellular progression. Overall, this study suggested that c-Myc-induced circ-NOTCH1 promoted malignant phenotypes of NPC cells by regulating the miR-34c-5p/c-Myc axis.

Bridging the Metabolic Parallels Between Neurological Diseases and Cancer

Despite the many recent breakthroughs in cancer research, oncology has traditionally been seen as a distinct field from other diseases. Recently, more attention has been paid to repurposing established therapeutic strategies and targets of other diseases towards cancer treatment, with some of these attempts generating promising outcomes [1, 2]. Recent studies using advanced metabolomics technologies [3] have shown evidence of close metabolic similarities between cancer and neurological diseases. These studies have unveiled several metabolic characteristics shared by these two categories of diseases, including metabolism of glutamine, gamma-aminobutyric acid (GABA), and N-acetyl-aspartyl-glutamate (NAAG) [4-6]. The striking metabolic overlap between cancer and neurological diseases sheds light on novel therapeutic strategies for cancer treatment. For example, 2-(phosphonomethyl) pentanedioic acid (2-PMPA), one of the glutamate carboxypeptidase II (GCP II) inhibitors that prevent the conversion of NAAG to glutamate, has been shown to suppress cancer growth [6, 7]. These promising results have led to an increased interest in integrating this metabolic overlap between cancer and neurological diseases into the study of cancer metabolism. The advantages of studying this metabolic overlap include not only drug repurposing but also translating existing knowledge from neurological diseases to the field of cancer research. This chapter discusses the specific overlapping metabolic features between cancer and neurological diseases, focusing on glutamine, GABA, and NAAG metabolisms. Understanding the interconnections between cancer and neurological diseases will guide researchers and clinicians to find more effective cancer treatments.

An Integrated Analysis of mRNAs and miRNAs Microarray Profiles to Screen miRNA Signatures Involved in Nasopharyngeal Carcinoma

OBJECTIVE

We aim to identify several microRNAs (miRNAs/miRs)-messenger RNAs (mRNAs) biomarkers correlated to nasopharyngeal carcinoma (NPC) based on an integrated analysis of miRNA and mRNAs microarray expression profiles.

METHODS

The available mRNA and miRNA microarray datasets were retrieved from Gene Expression Omnibus (GEO) database according to pre-determined screening criteria. Differentially expressed miRNA and mRNAs (DEmiRNAs and DEmRNAs) were extracted between NPC and noncancerous nasopharyngeal tissues. The target genes of DEmiRNAs were predicted with miRTarBase followed by the construction of DEmiRNAs-target DEmRNAs network, and functional analyses were performed. The DEmiRNAs expressions were validated and the performance of these DEmiRNAs was assessed by the area under the curve (AUC) values. Finally, the correlations between DEmiRNAs and specific clinical factors were analyzed.

RESULTS

There were 1140 interaction pairs (including let-7d/f-MYC/HMGA2 and miR-452-ITGA9) in DEmiRNAs-target DEmRNAs network. The GO annotation analysis showed that several genes such as MYC, HMGA2 and ITGA9 primarily participated in cellular process. KEGG analysis showed that these targets were associated with cell cycle and cancer-related pathways. Down-regulated let-7(-d and -f) and up-regulated miR-452 were verified in datasets. The AUC values of these 3 DEmiRNAs (let-7d, let-7-f and miR-452) was 0.803, 0.835 and 0.735, respectively. Besides, miR-452 was significantly related to survival rate of NPC patients.

CONCLUSION

The findings implied let-7d/f-MYC/HMGA2 and miR-452-ITGA9 might be promising targets for the detection and treatment of NPC.

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.

Transcriptional regulation of the bovine FGFR1 gene facilitates myoblast proliferation under hypomethylation of the promoter

DNA methylation, which can affect the expression level of genes, is one of the most vital epigenetic modifications in mammals. Fibroblast growth factor receptor 1 (FGFR1) plays an important role in muscle development; however, DNA methylation of the FGFR1 promoter has not been studied to date in cattle. Our study focused on methylation of the FGFR1 promoter and its effect on bovine myoblast proliferation and differentiation. We identified the FGFR1 core promoter by using luciferase reporter assays; we then studied FGFR1 expression by reverse transcription quantitative polymerase chain reaction, and the methylation pattern in the FGFR1 core promoter by bisulfite sequencing polymerase chain reaction in bovine muscle tissue at three different developmental stages. We used RNAi strategy to investigate the function of FGFR1 in myoblast proliferation and differentiation. Results showed that the FGFR1 core promoters were located at the R2 (-509 to ~-202 bp) and R4 (-1295 to ~-794 bp) regions upstream of the FGFR1 gene. FGFR1 expression level was negatively associated with the degree of methylation of the FGFR1 core promoter during the developmental process. In addition, we found that FGFR1 can promote myoblast proliferation, but had no effect on myoblast differentiation. In conclusion, our results suggest that FGFR1 can promote myoblast proliferation and its transcription can be regulated by the methylation level of the core promoter. Our findings provide a mechanistic basis for the improvement of animal breeding.

Generation of novel affibody molecules targeting the EBV LMP2A N-terminal domain with inhibiting effects on the proliferation of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) induced by latent infection with Epstein-Barr virus (EBV) remains the most common head and neck cancer in Southeast Asia, especially in the southern part of China. It is well known that persistent expression of two EBV latent membrane proteins (LMP1/LMP2A) plays a key role in nasopharyngeal carcinogenesis. Therefore, the therapeutic approach of targeting the LMP1/LMP2A protein and subsequently blocking the LMP1/LMP2A-mediated signalling pathway has been considered for treating patients with NPC. Recently, affibody molecules, a new class of small (~6.5 kDa) affinity proteins, have been confirmed to be powerful generalisable tools for developing imaging or therapeutic agents by targeting specific molecules. In this study, three EBV LMP2A N-terminal domain-binding affibody molecules (Z_LMP2A-N85, Z_LMP2A-N110 and Z_LMP2A-N252) were identified by screening a phage-displayed peptide library, and their high affinity and specificity for the EBV LMP2A N-terminal domain were confirmed by surface plasmon resonance (SPR), indirect immunofluorescence, co-immunoprecipitation and near-infrared small animal fluorescence imaging in vitro and in vivo. Moreover, affibody molecules targeting the EBV LMP2A N-terminal domain significantly reduced the viability of the EBV-positive cell lines C666-1, CNE-2Z and B95-8. Further investigations showed that affibody Z_LMP2A-N110 could inhibit the phosphorylation of AKT, GSK-3β and β-catenin signalling proteins, leading to suppression of β-catenin nuclear translocation and subsequent inhibition of c-Myc oncogene expression, which may be responsible for the reduced viability of NPC-derived cell lines. In conclusion, our findings provide a strong evidence that three novel EBV LMP2A N-terminal domain-binding affibody molecules have great potential for utilisation and development as agents for both molecular imaging and targeted therapy of EBV-related NPC.

Expression and Significance of LncRNA-MINCR and CDK2 mRNA in Primary Hepatocellular Carcinoma

OBJECTIVE

To investigate the expression of long-chain non-coding RNA MINCR (LncRNAMINCR) and Cyclin-Dependent Kinase 2 (CDK2) mRNA in primary hepatocellular carcinoma, and to analyze the relationship between its expression and clinical pathological parameters and prognosis of hepatocellular carcinoma.

METHODS

Seventy-five surgically resected primary hepatocellular carcinoma tissues and paracancerous tissues were selected. Real-time PCR was used to detect the expression of LncRNA-MINCR and CDK2 mRNA in hepatocellular carcinoma tissues and adjacent tissues. The relationship of clinicopathological parameters and prognosis between hepatocellular carcinoma and LncRNA-MINCR and CDK2 mRNA were analyzed. Pearson correlation coefficient describes the correlation between LncRNA-MINCR and CDK2 mRNA.

RESULTS

The expression of LncRNA-MINCR and CDK2 mRNA in primary hepatocellular carcinoma tissues was higher than that in the adjacent tissues [(5.51±0.62) vs (1.62±0.51), (4.52±0.73) vs (1.85±0.95), P<0.05]. The expression of LncRNA-MINCR in the primary hepatocellular carcinoma group was positively correlated with CDK2 mRNA (r=0.352, P<0.05), and the expression of LncRNA-MINCR in the paracancerous tissue group was not correlated with CDK2 mRNA (r=0.024, P>0.05). LncRNA-MINCR expression was associated with TNM staging, lymph node metastasis, and cirrhosis (P<0.05). CDK2 mRNA expression was associated with tumor diameter, TNM stage, lymph node metastasis, and serum alpha-fetoprotein levels (P<0.05). The 3-year survival rate of patients with high expression of LncRNAMINCR was lower than that of LncRNA-MINCR low expression group [53.49% vs 77.38%, 2=13.024, P<0.05). The 3-year survival rate of patients with high CDK2 mRNA expression was lower than that of CDK2 mRNA low expression group [51.29] % vs 80.38%, 2 = 10.15, P < 0.05].

CONCLUSION

The expression of LncRNA-MINCR and CDK2 mRNA in primary hepatocellular carcinoma tissues increased significantly. The two play a synergistic role in the invasion, invasion and metastasis of hepatocarcinoma cells. High expression of LncRNA-MINCR and CDK2 mRNA indicates poor prognosis in patients with hepatocellular carcinoma.

JQ1 inhibits tumour growth in combination with cisplatin and suppresses JAK/STAT signalling pathway in ovarian cancer

BACKGROUND

Overexpression of c-Myc is commonly seen in human ovarian cancers, and this could be a potentially novel therapeutic target for this disease. JQ1, a selective small-molecule BET (Bromodomain and extraterminal domain family) bromodomain (BRDs) inhibitor, has been found to suppress tumour progression in several cancer cell types.

RESULTS

Using a panel of ovarian cancer cell lines and primary cell cultures from human ovarian cancer ascites, we demonstrated that JQ1 significantly suppressed cell proliferation and induced apoptosis in an ovarian cancer cell by targeting BRD4 and c-Μyc. In addition, JQ1 sensitized ovarian cancer cells to cisplatin, the most commonly used chemotherapeutic agent in ovarian cancer. Importantly, this effect was observed in ovarian cells, which exhibited resistance to cisplatin alone. Finally, we show that JQ1 interacts with the JAK-STAT signalling pathway, a pathway important in supporting ovarian cancer cell survival by suppressing or inducing genes involved in cell survival and apoptosis, respectively.

CONCLUSION

Our data, taken together, suggest that JQ1 is an attractive antitumour candidate for further investigation in the treatment of ovarian cancer, as it associates with cell proliferation, apoptosis, and alterations in the JAK-STAT signalling pathway, especially in patients with a platinum-resistant profile or in patients with relapsed disease.

The combination of lonafarnib and sorafenib induces cyclin D1 degradation via ATG3-mediated autophagic flux in hepatocellular carcinoma cells

Combination treatment is a promising strategy to improve prognosis of hepatocellular carcinoma (HCC). Sorafenib is a traditional first-line agent approved for the treatment of advanced HCC, though with limited efficacy. Previously, we reported that lonafarnib, an orally bioavailable non-peptide inhibitor targeting farnesyltransferase, synergizes with sorafenib against the growth of HCC cells. In the present study, we aim to clarify the underlying mechanism of this combination strategy. Initially, using in vitro HCC cell model, we confirmed that synergistic treatment of lonafarnib and sorafenib suppressed cell viability and colony formation, and induced cell death. We then found conversion of LC3-I to LC3-II via combination the treatment and observed formation of autophagosomes by electron microscopy. Knockdown of ATG3 inhibited the autophagic flux induced by the combination treatment. Furthermore, we demonstrated that drug-eliciting autophagy selectively promoted the degradation of cyclin D1 in a lysosome-dependent manner and subsequently inhibited DNA synthesis through downregulating the phosphorylation of Rb protein. In conclusion, our results provide a deeper insight into the mechanism for the combination treatment of lonafarnib and sorafenib in HCC therapy.

Aberrant MFN2 transcription facilitates homocysteine-induced VSMCs proliferation via the increased binding of c-Myc to DNMT1 in atherosclerosis

It is well‐established that homocysteine (Hcy) is an independent risk factor for atherosclerosis. Hcy can promote vascular smooth muscle cell (VSMC) proliferation, it plays a key role in neointimal formation and thus contribute to arteriosclerosis. However, the molecular mechanism on VSMCs proliferation underlying atherosclerosis is not well elucidated. Mitofusin‐2 (MFN2) is an important transmembrane GTPase in the mitochondrial outer membrane and it can block cells in the G0/G1 stage of the cell cycle. To investigate the contribution of aberrant MFN2 transcription in Hcy‐induced VSMCs proliferation and the underlying mechanisms. Cell cycle analysis revealed a decreased proportion of VSMCs in G0/G1 and an increased proportion in S phase in atherosclerotic plaque of APOE^−/− mice with hyperhomocystinaemia (HHcy) as well as in VSMCs exposed to Hcy in vitro. The DNA methylation level of MFN2 promoter was obviously increased in VSMCs treated with Hcy, leading to suppressed promoter activity and low expression of MFN2. In addition, we found that the expression of c‐Myc was increased in atherosclerotic plaque and VSMCs treated with Hcy. Further study showed that c‐Myc indirectly regulates MFN2 expression is duo to the binding of c‐Myc to DNMT1 promoter up‐regulates DNMT1 expression leading to DNA hypermethylation of MFN2 promoter, thereby inhibits MFN2 expression in VSMCs treated with Hcy. In conclusion, our study demonstrated that Hcy‐induced hypermethylation of MFN2 promoter inhibits the transcription of MFN2, leading to VSMCs proliferation in plaque formation, and the increased binding of c‐Myc to DNMT1 promoter is a new and relevant molecular mechanism.

Wnt/β-Catenin Signaling Pathway-Related Proteins (DKK-3, β-Catenin, and c-MYC) Are Involved in Prognosis of Nasopharyngeal Carcinoma

The Wnt/β-catenin signaling pathway is one of the highly conserved signaling pathway widely reported to play essential roles in the development of various tumors and human cancers, thus serving as a potential target for anticancer therapy. However, the specific effects of the related proteins in the Wnt/β-catenin signaling pathway in nasopharyngeal carcinoma (NPC) still remain elusive. Thus, this study was performed to uncover the correlation between the Wnt/β-catenin signaling pathway-related proteins and the clinical characteristics and prognosis of NPC. NPC tissues were revealed to present high expression of β-catenin and v-myc myelocytomatosis viral oncogene homolog (c-MYC) but low expression of Dickkopf-3 (DKK-3). Immunohistochemical staining revealed that DKK-3 was positively linked to but β-catenin and c-MYC were negatively linked to differentiation, tumor-node-metastasis (TNM) stage and lymph node metastasis of patients with NPC. In addition, c-MYC was identified to be positively correlated to DKK-3 in NPC tissues. The positive expression of β-catenin and c-MYC had negative relations with and that of DKK-3 had positive relations with survival rate of patients with NPC, which was analyzed by Kaplan-Meier method. Moreover, it was shown that later TNM stage and positive expression of β-catenin were risk factors for NPC-related death. These findings provide evidence that the proteins related to the Wnt/β-catenin signaling pathway (DKK-3, β-catenin, and c-MYC) participate in the development of NPC and positive expression of DKK-3 and negative expression of β-catenin, and c-MYC can serve as essential prognostic biomarkers, shedding new light on the prognosis and treatment of NPC.

X chromosome-linked long noncoding RNA lnc-XLEC1 regulates c-Myc-dependent cell growth by collaborating with MBP-1 in endometrial cancer

LncRNAs (long noncoding RNAs) are noncoding transcripts that are more than 200 nt long and have been described as the largest subclass in the noncoding transcriptome in humans. Although studies of lncRNAs in cancer have been continuing for a long time, no much has been known about X chromosome-linked lncRNAs. Here, by using RNA-seq we report the identification of a new X chromosome-linked lncRNA (lnc-XLEC1) that is aberrantly downregulated during the development of endometrial carcinoma (EC). The overexpression of lnc-XLEC1 reduces the migration and proliferation of EC cells. Flow cytometry analysis indicated that lnc-XLEC1 overexpression resulted in a substantial accumulation of EC cells in the G1 phase. In addition, lnc-XLEC1 had inhibitive effects that may result from its collaboration with MBP-1 during the suppression of the c-Myc expression and the negative regulating of the Cdk/Rb/E2F pathway. The anti-tumor effects of lnc-XLEC1 on EC progression suggest that lnc-XLEC1 has some potential value in anti-carcinoma therapies and deserves further investigation. Our study reported for the first time that the lnc-XLEC1 might be related to the incidence and prognosis of EC. Moreover, we discovered that this process might be related to somatic X dosage compensation and skewed X chromosome inactivation (SXCI).

Zinc-finger protein YY1 suppresses tumor growth of human nasopharyngeal carcinoma by inactivating c-Myc-mediated microRNA-141 transcription

Yin Yang 1 (YY1) is a zinc-finger protein that plays critical roles in various biological processes by interacting with DNA and numerous protein partners. YY1 has been reported to play dual biological functions as either an oncogene or tumor suppressor in the development and progression of multiple cancers, but its role in human nasopharyngeal carcinoma (NPC) has not yet been revealed. In this study, we found that YY1 overexpression significantly inhibits cell proliferation and cell-cycle progression from G₁ to S and promotes apoptosis in NPC cells. Moreover, we identified YY1 as a component of the c-Myc complex and observed that ectopic expression of YY1 inhibits c-Myc transcriptional activity, as well as the promoter activity and expression of the c-Myc target gene microRNA-141 (miR-141). Furthermore, restoring miR-141 expression could at least partially reverse the inhibitory effect of YY1 on cell proliferation and tumor growth and on the expression of some critical c-Myc targets, such as PTEN/AKT pathway components both in vitro and in vivo We also found that YY1 expression is reduced in NPC tissues, negatively correlates with miR-141 expression and clinical stages in NPC patients, and positively correlates with survival prognosis. Our results reveal a previously unappreciated mechanism in which the YY1/c-Myc/miR-141 axis plays a critical role in NPC progression and may provide some potential and valuable targets for the diagnosis and treatment of NPC.

Stevioside inhibits experimental fibrosis by down-regulating profibrotic Smad pathways and blocking hepatic stellate cell activation

Liver cirrhosis is associated with increased morbidity and mortality with important health and social consequences; however, an effective treatment has not been found yet. Previous reports have shown some beneficial effects of stevioside (SVT) in different diseases, but the ability of SVT to inhibit liver cirrhosis has not been reported. Therefore, we studied the potential of this diterpenoid to inhibit liver cirrhosis induced by thioacetamide, a model that shares many similarities with the human disease, and investigated the possible underlying molecular mechanism using in vivo and in vitro approaches. Cirrhosis was induced in male Wistar rats by chronic thioacetamide administration (200 mg/kg) intraperitoneally three times per week. Rats received saline or SVT (20 mg/kg) two times daily intraperitoneally. In addition, co-cultures were incubated with either lipopolysaccharide or ethanol. Liver fibrosis, hepatic stellate cells activation, metalloproteinases activity, canonical and non-canonical Smads pathway and expression of several profibrogenic genes were evaluated. Thioacetamide activated hepatic stellate cells and distorted the liver parenchyma with the presence of abundant thick bands of collagen. In addition, thioacetamide up-regulated the protein expression of α-smooth muscle actin, transforming growth factor-β1, metalloproteinases-9,-2 and -13 and overstimulate the canonical and non-canonical Smad pathways. SVT administration inhibited all of these changes. In vitro, SVT inhibited the up-regulation of several genes implicated in cirrhosis when cells were exposed to lipopolysaccharides or ethanol. We conclude that SVT inhibited liver damage by blocking hepatic stellate cells activation, down-regulating canonical and non-canonical profibrotic Smad pathways.

A Functional 5'-UTR Polymorphism of MYC Contributes to Nasopharyngeal Carcinoma Susceptibility and Chemoradiotherapy Induced Toxicities

MYC is a transcription factor acting as a pivotal regulator of genes involved in cell cycle progression, apoptosis, differentiation and metabolism. In this study, we evaluated the association of MYC polymorphisms with nasopharyngeal carcinoma (NPC) risk and chemoradiotherapy induced toxicities among Chinese population. By using bioinformatic tools, five potential functional single nucleotide polymorphisms of MYC were genotyped in a case-control study with 684 NPC patients and 823 healthy controls. We found two SNPs rs4645948 (C>T) and rs2071346 (G>T) were significantly associated with increased risk of developing NPC (TT+CT vs CC, OR=1.557, P=3.34×10^-4; TT+GT vs GG, OR=1.361, P=0.007, respectively). In addition, rs4645948 (C>T) was conferred with increased risk of anemia (CT vs CC, OR=2.152, P=0.001) and severe leukopenia (CT vs CC, OR=1.893, P=0.034) for NPC patients receiving chemoradiotherapy. We also found rs2071346 (G>T) variant genotype carriers were subjected to higher risk of anemia (GT vs GG, OR=1.665, P=0.022) and thrombocytopenia (GT vs GG, OR=1.685, P=0.035). Our results demonstrated that the relative expression of MYC was dramatically higher in NPC tissues compared to rhinitis tissues. Over-expression of MYC was positively correlated with advanced T stage, N stage, and late clinical stage. Notably, the expression of MYC in rs4645948 CT and TT genotypes carriers were significantly higher than CC genotype carriers. Luciferase reporter assay indicated that the T allele of rs4645948 led to significantly higher transcription activity of MYC compared to the C allele. These findings suggested that individual carrying the rs4645948 T allele may be at greater risk for NPC due to an increase of MYC transcriptional activity and an augment of MYC expression.

The anticancer mechanism investigation of Tanshinone IIA by pharmacological clustering in protein network

BACKGROUND

Cancer is the second most common cause of death globally. The anticancer effects of Tanshinone II_A (Tan II_A) has been confirmed by numerous researches. However, the underlying mechanism remained to be integrated in systematic format. Systems biology embraced the complexity of cancer; therefore, a system study approach was proposed in the present study to explore the anticancer mechanism of Tan II_A based on network pharmacology.

METHOD

Agilent Literature Search (ALS), a text-mining tool, was used to pull protein targets of Tan II_A. Then, pharmacological clustering was applied to classify obtained hits, the anticancer module was analysed further. The top ten essential nodes in the anticancer module were obtained by ClusterONE. Functional units in the anticancer module were catalogued and validated by Gene Ontology (GO) analysis. Meanwhile, KEGG and Cell Signalling Technology Pathway were employed to provide pathway data for potential anticancer pathways construction. Finally, the pathways were plotted using Cytoscape 3.5.1. Furthermore, in vitro experiments with five carcinoma cell lines were conducted.

RESULTS

A total of 258 proteins regulated by Tan II_A were identified through ALS and were visualized by protein network. Pharmacological clustering further sorted 68 proteins that intimately involved in cancer pathogenesis based on Gene Ontology. Subsequently, pathways on anticancer effect of Tan II_A were delineated. Five functional units were clarified according to literature: including regulation on apoptosis, proliferation, sustained angiogenesis, autophagic cell death, and cell cycle. The GO analysis confirmed the classification was statistically significant. The inhibiting influence of Tan II_A on p70 S6K/mTOR pathway was revealed for the first time. The in vitro experiments displayed the selectivity of Tan II_A on HeLa, MDA-MB-231, HepG2, A549, and ACHN cell lines, the IC₅₀ values were 0.54 μM, 4.63 μM, 1.42 μM, 17.30 μM and 204.00 μM, respectively. This result further reinforced the anticancer effect of Tan II_A treatment.

CONCLUSIONS

The current study provides a systematic methodology for discovering the coordination of the anticancer pathways regulated by Tan II_A via protein network. And it also offers a valuable guidance for systematic study on the therapeutic values of other herbs and their active compounds.

The nucleolus, an ally, and an enemy of cancer cells

The rates of ribosome production by a nucleolus and of protein biosynthesis by ribosomes are tightly correlated with the rate of cell growth and proliferation. All these processes must be matched and appropriately regulated to provide optimal cell functioning. Deregulation of certain factors, including oncogenes, controlling these processes, especially ribosome biosynthesis, can lead to cell transformation. Cancer cells are characterized by intense ribosome biosynthesis which is advantageous for their growth and proliferation. On the other hand, this feature can be engaged as an anticancer strategy. Numerous nucleolar factors such as nucleolar and ribosomal proteins as well as different RNAs, in addition to their role in ribosome biosynthesis, have other functions, including those associated with cancer biology. Some of them can contribute to cell transformation and cancer development. Others, under stress evoked by different factors which often hamper function of nucleoli and thus induce nucleolar/ribosomal stress, can participate in combating cancer cells. In this sense, intentional application of therapeutic agents affecting ribosome biosynthesis can cause either release of these molecules from nucleoli or their de novo biosynthesis to mediate the activation of pathways leading to elimination of harmful cells. This review underlines the role of a nucleolus not only as a ribosome constituting apparatus but also as a hub of both positive and negative control of cancer development. The article is mainly based on original papers concerning mechanisms in which the nucleolus is implicated directly or indirectly in processes associated with neoplasia.

BRD7 expression and c-Myc activation forms a double-negative feedback loop that controls the cell proliferation and tumor growth of nasopharyngeal carcinoma by targeting oncogenic miR-141

Background

miR-141 is up-regulated and plays crucial roles in nasopharyngeal carcinoma (NPC). However, the molecular mechanism underlying the dysregulation of miR-141 is still obscure.

Methods

Thus, the ChIP-PCR was performed to identify the c-Myc-binding sites in miR-141 and BRD7. qRT-PCR, western blot and immunohistochemistry assays were used to detect the expression of miR-141 and its up/down stream molecules. The rescue experiments on the c-Myc/miR-141 axis were performed in vitro and in vivo.

Results

Our results showed that the levels of mature miR-141, pre-miR-141 and pri-miR-141 were downregulated in c-Myc knockdown NPC cells. Meanwhile, c-Myc transactivates the expression of miR-141 by binding its promoter region. Moreover, BRD7 was identified as a co-factor of c-Myc to negatively regulate the activation of c-Myc/miR-141 axis, as well as a direct target of c-Myc. Moreover, restoration of miR-141 in c-Myc knockdown NPC cells notably rescued the effect of c-Myc on cell proliferation and tumor growth, as well as the blocking of PTEN/AKT pathway. Additionally, the expression of c-Myc was positively correlated with that of miR-141 and the clinical stages of NPC patients and negatively associated with the expression of BRD7. Our findings demonstrated that BRD7 expression and c-Myc activation forms a negative feedback loop to control the cell proliferation and tumor growth by targeting miR-141.

Conclusions

These observations provide new mechanistic insights into the dysregulation of miR-141 expression and a promising therapeutic option for NPC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0734-2) contains supplementary material, which is available to authorized users.

Effects of Klf4 and c-Myc Knockdown on Pluripotency Maintenance in Porcine Induced Pluripotent Stem Cell

Objective

The importance of Oct4 and Sox2 in maintaining pluripotency and self-renewal is well-understood, but the functions of Klf4 and c-Myc has not been fully investigated. In the present study, we attempted to determine the roles of Klf4 and c-Myc on pluripotency maintenance of porcine induced pluripotent stem (piPS) cells.

Materials and Methods

In this experimental study, we performed short hairpin RNA (shRNA) to knock down the Klf4 and c-Myc functions of piPS cells and examined pluripotency markers and teratoma formation to evaluate piPS cell pluripotency. The shRNA-Klf4 and shRNA-c-Myc vectors containing a reporter gene, TagFP635, were transfected into piPS cells by lentivirus infection. The piPS cells fully expressing infrared fluorescence were selected to confirm gene knockdown of Klf4 and c-Myc reverse transcription-polymerase chain reaction (RT-PCR). Next, for pluripotency evaluation, expression of pluripotency markers was detected by immunocytochemical staining, and capability of teratoma formation was investigated by piPS cell transplantation into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice.

Results

Our findings indicated that Klf4 and c-Myc functions of piPS cells were knocked down by shRNA transfection, and knockdown of Klf4 and c-Myc functions impaired expression of pluripotency markers such as Oct4, AP, SSEA-3, SSEA-4, TRA-1-6, and TRA-1-81. Furthermore, piPS cells without Klf4 and c-Myc expression failed to form teratomas.

Conclusion

The pluripotency of piPS cells are crucially dependent upon Klf4 and c-Myc expression. These findings, suggesting potential mechanisms of Klf4 and c-Myc contribution to piPS cell formation, have important implications for application, regulation, and tumorigenesis of piPS cells.

HN1 contributes to migration, invasion, and tumorigenesis of breast cancer by enhancing MYC activity

BACKGROUND

Hematological and neurological expressed 1 (HN1) is upregulated in many tumors, but the role of HN1 in breast cancer progression and its regulatory mechanism have not been well understood.

METHODS

To study the role of HN1 in the initiation and progression of breast cancer, we examined HN1 levels in breast cancer cells and tissues and analyzed the relationship between HN1 levels and patient survival. We used mammosphere formation assay, side population analysis, wound healing assay, transwell assay, soft agar formation assay, and xenografted tumor model to determine the effect of HN1 on the expansion of breast cancer stem cells, and the migration, invasion and tumorigenesis of breast cancer. To determine whether HN1 regulates MYC, we used quantitative real-time PCR and Western blot analysis to assess the expression of MYC and their targeted genes to determine the phenotype caused by knockdown of MYC in breast cancer cell with HN1 overexpression.

RESULTS

In this study, we found that HN1 was upregulated in breast cancer tissues. Patients with high levels of HN1 expression had significantly shorter survival than those with low HN1 expression. In breast cancer cell line, ectopic overexpression of HN1 not only promoted the expansion of breast cancer stem cells, but also promoted cell migration, invasion, and tumorigenesis, while knockdown of HN1 reduced these effects. Furthermore, there was a positive correlation between MYC (also known as c-MYC) level and HN1 level, mechanism analysis suggested HN1 promoted the expression of MYC and its targeted genes like CDK4, CCND1, p21, CAV1, and SFRP1. Downregulation of MYC abrogated the effect of HN1 overexpression in breast cancer cell lines.

CONCLUSION

Taken together, these data reveal that HN1 promotes the progression of breast cancer by upregulating MYC expression, and might be a therapeutic target for breast cancer.

TRIM24 promotes the aggression of gastric cancer via the Wnt/β-catenin signaling pathway

Tripartite motif-containing 24 (TRIM24) is important in tumor development and progression. However, the role of TRIM24 in gastric cancer (GC) and the mechanisms underlying the dysregulated expression of TRIM24 remain to be fully elucidated. In the present study, it was found that TRIM24 was frequently overexpressed in GC cell lines and tissues compared with normal controls, as determined by western blotting and immunohistochemical staining. The high nuclear expression of TRIM24 was correlated with the depth of invasion (P=0.007), tumor-node-metastasis stage (P=0.005), and lymph node metastasis (P=0.027), and shorter overall survival rates (P=0.010) in patients with GC. Small interfering RNA-mediated knockdown of TRIM24 inhibited cell proliferation, colony formation, migration, invasion and the nuclear accumulation of β-catenin, and it delayed cell cycle progression and induced apoptosis. In addition, the expression of TRIM24 was positively correlated with that of β-catenin in GC tissues. TRIM24 knockdown decreased the expression of Wnt/β-catenin target genes, whereas the activation of Wnt/β-catenin signaling by lithium chloride reversed the effects of TRIM24 knockdown. Taken together, these data suggested that TRIM24 was a prognostic or potential therapeutic target for patients with GC and was important in the activation of the Wnt/β-catenin pathway during the progression of GC.

Effects of alcohol on c-Myc protein in the brain

Alcoholism is a disorder categorized by significant impairment that is directly related to persistent and extreme use of alcohol. The effects of alcoholism on c-Myc protein expression in the brain have been scarcely studied. This is the first study to investigate the role different characteristics of alcoholism have on c-Myc protein in the brain. We analyzed c-Myc protein in the hypothalamus and amygdala from five different animal models of alcohol abuse. c-Myc protein was increased following acute ethanol exposure in a mouse knockout model and following chronic ethanol consumption in vervet monkeys. We also observed increases in c-Myc protein exposure in animals that are genetically predisposed to alcohol and methamphetamine abuse. Lastly, c-Myc protein was increased in animals that were acutely exposed to methamphetamine when compared to control treated animals. These results suggest that in substance abuse c-Myc plays an important role in the brain's response.

PFK15, a Small Molecule Inhibitor of PFKFB3, Induces Cell Cycle Arrest, Apoptosis and Inhibits Invasion in Gastric Cancer

PFKFB3 (6-phosphofructo-2-kinase) synthesizes fructose 2,6-bisphosphate (F2,6P₂), which is an allosteric activator of 6-phosphofructo-1-kinase (PFK-1), the rate-limiting enzyme of glycolysis. Overexpression of the PFKFB3 enzyme leads to high glycolytic metabolism, which is required for cancer cells to survive in the harsh tumor microenvironment. The objective of this study was to investigate the antitumor activity of PFK15 (1-(4-pyridinyl)-3-(2-quinolinyl)-2-propen-1-one), a small molecule inhibitor of PFKFB3, against gastric cancer and to explore its potential mechanisms. The effects of PFK15 on proliferation, apoptosis and cell cycle progression in gastric cancer cells were evaluated by cytotoxicity and apoptosis assays, flow cytometry, and western blotting. In addition, the invasion inhibition effects of PFK15 were measured by transwell invasion assay and western blot analysis, and a xenograft tumor model was used to verify the therapeutic effect of PFK15 in vivo. Results showed that PFK15 inhibited the proliferation, caused cell cycle arrest in G0/G1 phase by blocking the Cyclin-CDKs/Rb/E2F signaling pathway, and induced apoptosis through mitochondria in gastric cancer cells. Tumor volume and weight were also significantly reduced upon intraperitoneal injection with PFK15 at 25 mg/kg. In addition, PFK15 inhibited the invasion of gastric cancer cells by downregulating focal adhesion kinase (FAK) expression and upregulating E-cadherin expression. Taken together, our findings indicate that PFK15 is a promising anticancer drug for treating gastric cancer.

The adenoviral E1A N-terminal domain represses MYC transcription in human cancer cells by targeting both p300 and TRRAP and inhibiting MYC promoter acetylation of H3K18 and H4K16

Human cancers frequently arise from increased expression of proto-oncogenes, such as MYC and HER2. Understanding the cellular pathways regulating the transcription and expression of proto-oncogenes is important for targeted therapies for cancer treatment. Adenoviral (Ad) E1A 243R (243 aa residues) is a viral oncoprotein that interacts with key regulators of gene transcription and cell proliferation. We have shown previously that the 80 amino acid N-terminal transcriptional repression domain of E1A 243R (E1A 1-80) can target the histone acetyltransferase (HAT) p300 and repress HER2 in the HER2-overexpressing human breast cancer cell line SKBR3. Expression of E1A 1-80 induces death of SKBR3 and other cancer cell lines. In this study, we performed total cell RNA sequence analysis and identified MYC as the regulatory gene for cellular proliferation most strongly repressed by E1A 1-80. By RT-quantitative PCR analysis we show that repression of MYC in SKBR3 cells occurs early after expression of E1A 1-80, suggesting that MYC may be an early responder of E1A 1-80-mediated transcriptional repression. Of interest, while E1A 1-80 repression of MYC occurs in all eight human cancer cell lines examined, repression of HER2 is cell-type dependent. We demonstrate by ChIP analysis that MYC transcriptional repression by E1A 1-80 is associated with inhibition of acetylation of H3K18 and H4K16 on the MYC promoter, as well as inhibition of RNA Pol II binding to the MYC promoter. Deletion mutant analysis of E1A 1-80 suggests that both p300/CBP and TRRAP are involved in E1A 1-80 repression of MYC transcription. Further, E1A 1-80 interaction with p300/CBP and TRRAP is correlated with inhibition of H3K18 and H4K16 acetylation on the MYC promoter, respectively. Our results indicate that E1A 1-80 may target two important pathways for histone modification to repress transcription in human cancer cells.

Downregulation of SATB1 increases the invasiveness of Jurkat cell via activation of the WNT/β-catenin signaling pathway in vitro

Special AT-rich sequence-binding protein-1 (SATB1) is critical for genome organizer that reprograms chromatin organization and transcription profiles, and associated with tumor growth and metastasis in several cancer types. Many studies suggest that SATB1 overexpression is an indicator of poor prognosis in various cancers, such as breast cancer, malignant cutaneous melanoma, and liver cancer. However, their expression patterns and function values for adult T cell leukemia (ATL) are still largely unknown. The aim of this study is to examine the levels of SATB1 in ATL and to explore its function and mechanisms in Jurkat cell line. Here, we reported that SATB1 expressions were decreased in ATL cells (p < 0.001) compared with normal controls. Knockdown of SATB1 expression significantly enhanced invasion of Jurkat cell in vitro. Furthermore, knockdown of SATB1 gene enhances β-catenin nuclear accumulation and transcriptional activity and thus may increase the invasiveness of Jurkat cell through the activation of Wnt/β-catenin signaling pathway in vitro.

Triphala Extract Suppresses Proliferation and Induces Apoptosis in Human Colon Cancer Stem Cells via Suppressing c-Myc/Cyclin D1 and Elevation of Bax/Bcl-2 Ratio

Colon cancer is the second leading cause of cancer related deaths in the USA. Cancer stem cells (CSCs) have the ability to drive continued expansion of the population of malignant cells. Therefore, strategies that target CSCs could be effective against colon cancer and in reducing the risk of relapse and metastasis. In this study, we evaluated the antiproliferative and proapoptotic effects of triphala, a widely used formulation in Indian traditional medicine, on HCT116 colon cancer cells and human colon cancer stem cells (HCCSCs). The total phenolic content, antioxidant activity, and phytochemical composition (LC-MS-MS) of methanol extract of triphala (MET) were also measured. We observed that MET contains a variety of phenolics including naringin, quercetin, homoorientin, and isorhamnetin. MET suppressed proliferation independent of p53 status in HCT116 and in HCCSCs. MET also induced p53-independent apoptosis in HCCSCs as indicated by elevated levels of cleaved PARP. Western blotting data suggested that MET suppressed protein levels of c-Myc and cyclin D1, key proteins involved in proliferation, and induced apoptosis through elevation of Bax/Bcl-2 ratio. Furthermore, MET inhibited HCCSCs colony formation, a measure of CSCs self-renewal ability. Anticancer effects of triphala observed in our study warrant future studies to determine its efficacy in vivo.