Ube2v1-mediated ubiquitination and degradation of Sirt1 promotes metastasis of colorectal cancer by epigenetically suppressing autophagy

Sirtuins' control of autophagy and mitophagy in cancer

Mammalian cells use a specialized and complex machinery for the removal of altered proteins or dysfunctional organelles. Such machinery is part of a mechanism called autophagy. Moreover, when autophagy is specifically employed for the removal of dysfunctional mitochondria, it is called mitophagy. Autophagy and mitophagy have important physiological implications and roles associated with cellular differentiation, resistance to stresses such as starvation, metabolic control and adaptation to the changing microenvironment. Unfortunately, transformed cancer cells often exploit autophagy and mitophagy for sustaining their metabolic reprogramming and growth to a point that autophagy and mitophagy are recognized as promising targets for ongoing and future antitumoral therapies. Sirtuins are NAD+ dependent deacylases with a fundamental role in sensing and modulating cellular response to external stresses such as nutrients availability and therefore involved in aging, oxidative stress control, inflammation, differentiation and cancer. It is clear, therefore, that autophagy, mitophagy and sirtuins share many common aspects to a point that, recently, sirtuins have been linked to the control of autophagy and mitophagy. In the context of cancer, such a control is obtained by modulating transcription of autophagy and mitophagy genes, by post translational modification of proteins belonging to the autophagy and mitophagy machinery, by controlling ROS production or major metabolic pathways such as Krebs cycle or glutamine metabolism. The present review details current knowledge on the role of sirtuins, autophagy and mitophagy in cancer to then proceed to discuss how sirtuins can control autophagy and mitophagy in cancer cells. Finally, we discuss sirtuins role in the context of tumor progression and metastasis indicating glutamine metabolism as an example of how a concerted activation and/or inhibition of sirtuins in cancer cells can control autophagy and mitophagy by impinging on the metabolism of this fundamental amino acid.

Theoretical and in silico Analyses Reveal MYC as a Dynamic Network Biomarker in Colon and Rectal Cancer

In this article, we make a theoretical and in silico study for uncovering and evaluating biomarkers in colon and rectal cancer (CRC) by the dynamic network biomarker (DNB) theory. We propose a strategy to employ the theoretical concept of UICC TNM classification in CRC. To reveal the critical transition of CRC, the DNB algorithm was implemented to analyze the genome-wide dynamic network through temporal gene expression data. The relationship between gene sets and clinical features was evaluated by weighted gene co-expression network analysis. The results show that MYC was significantly associated with tumor amplification, tumor immune cells, and survival times. The candidate tumor suppressor genes were ZBTB16, MAL, LIFR, and SLIT2. Protein-protein interaction (PPI) analysis shows that these candidate tumor suppressor genes were significant in immune cells. Data from the Human Protein Atlas showed that a high expression of these candidate tumor suppressor genes was associated with favorable prognosis in TNM stages I-IV. In conclusion, this work provides significant and novel information regarding the TNM stage, cause, and consequences of elevated MYC expression in CRC. MYC expression levels had significant negative correlations with tumor suppressor genes and immune cells.

The Roles of ceRNAs-Mediated Autophagy in Cancer Chemoresistance and Metastasis

Simple Summary

Chemoresistance and metastasis are the main causes of treatment failure in cancers. Autophagy contribute to the survival and metastasis of cancer cells. Competing endogenous RNA (ceRNA), particularly long non-coding RNAs and circular RNA (circRNA), can bridge the interplay between autophagy and chemoresistance or metastasis in cancers via sponging miRNAs. This review aims to discuss on the function of ceRNA-mediated autophagy in the process of metastasis and chemoresistance in cancers. ceRNA network can sequester the targeted miRNA expression to indirectly upregulate the expression of autophagy-related genes, and thereof participate in autophagy-mediated chemoresistance and metastasis. Our clarification of the mechanism of autophagy regulation in metastasis and chemoresistance may greatly improve the efficacy of chemotherapy and survival in cancer patients. The combination of the tissue-specific miRNA delivery and selective autophagy inhibitors, such as hydroxychloroquine, is attractive to treat cancer patients in the future.

Abstract

Chemoresistance and metastasis are the main causes of treatment failure and unfavorable outcome in cancers. There is a pressing need to reveal their mechanisms and to discover novel therapy targets. Autophagy is composed of a cascade of steps controlled by different autophagy-related genes (ATGs). Accumulating evidence suggests that dysregulated autophagy contributes to chemoresistance and metastasis via competing endogenous RNA (ceRNA) networks including lncRNAs and circRNAs. ceRNAs sequester the targeted miRNA expression to indirectly upregulate ATGs expression, and thereof participate in autophagy-mediated chemoresistance and metastasis. Here, we attempt to summarize the roles of ceRNAs in cancer chemoresistance and metastasis through autophagy regulation.

Dexmedetomidine protects against lidocaine-induced neurotoxicity through SIRT1 downregulation-mediated activation of FOXO3a

Lidocaine, a typical local anesthetic, has been shown to directly induce neurotoxicity in clinical settings. Dexmedetomidine (DEX) is an alpha-2-adrenoreceptor agonist that has been used as anxiolytic, sedative, and analgesic agent which has recently found to protect against lidocaine-induced neurotoxicity. Nicotinamide adenine dinucleotide-dependent deacetylase sirtuin-1 (SIRT1)/forkhead box O3 (FOXO3a) signaling is critical for maintaining neuronal function and regulation of the apoptotic pathway. In the present study, we designed in vitro and in vivo models to investigate the potential effects of lidocaine and DEX on SIRT1 and FOXO3a and to verify whether SIRT1/FOXO3a-mediated regulation of apoptosis is involved in DEX-induced neuroprotective effects against lidocaine. We found that in both PC12 cells and brains of mice, lidocaine decreased SIRT1 level through promoting the degradation of SIRT1 protein. Lidocaine also increased FOXO3a protein level and increased the acetylation of SIRT1 through inhibiting SIRT1. Upregulation of SIRT1 or downregulation of FOXO3a significantly inhibited lidocaine-induced changes in both cell viability and apoptosis. DEX significantly inhibited the lidocaine-induced decrease of SIRT1 protein level and increase of FOXO3a protein level and acetylation of FOXO3a. Downregulation of SIRT1 or upregulation of FOXO3a suppressed DEX-induced neuroprotective effects against lidocaine. The data suggest that SIRT1/FOXO3a is a potential novel target for alleviating lidocaine-induced neurotoxicity and provide more theoretical support for the use of DEX as an effective adjunct to alleviate chronic neurotoxicity induced by lidocaine.

Genetic susceptibility may modify the association between cell phone use and thyroid cancer: A population-based case-control study in Connecticut

Emerging studies have provided evidence on the carcinogenicity of radiofrequency radiation (RFR) from cell phones. This study aims to test the genetic susceptibility on the association between cell phone use and thyroid cancer. Population-based case-control study was conducted in Connecticut between 2010 and 2011 including 440 thyroid cancer cases and 465 population-based controls with genotyping information for 823 single nucleotide polymorphisms (SNPs) in 176 DNA genes. We used multivariate unconditional logistic regression models to estimate the genotype-environment interaction between each SNP and cell phone use and to estimate the association with cell phone use in populations according to SNP variants. Ten SNPs had P < 0.01 for interaction in all thyroid cancers. In the common homozygote groups, no association with cell phone use was observed. In the variant group (heterozygotes and rare homozygotes), cell phone use was associated with an increased risk for rs11070256 (odds ratio (OR): 2.36, 95% confidence interval (CI): 1.30-4.30), rs1695147 (OR: 2.52, 95% CI: 1.30-4.90), rs6732673 (OR: 1.59, 95% CI: 1.01-2.49), rs396746 (OR: 2.53, 95% CI: 1.13-5.65), rs12204529 (OR: 2.62, 95% CI: 1.33-5.17), and rs3800537 (OR: 2.64, 95% CI: 1.30-5.36) with thyroid cancers. In small tumors, increased risk was observed for 5 SNPs (rs1063639, rs1695147, rs11070256, rs12204529 and rs3800537), In large tumors, increased risk was observed for 3 SNPs (rs11070256, rs1695147, and rs396746). Our result suggests that genetic susceptibilities modify the associations between cell phone use and risk of thyroid cancer. The findings provide more evidence for RFR carcinogenic group classification.

Folate inhibits miR-27a-3p expression during cervical carcinoma progression and oncogenic activity in human cervical cancer cells

BACKGROUND

Folate deficiency has been long implicated in cancer development. Although the role of folate in preventing cervical cancer is still unclear, emerging evidence shows that microRNAs (miRs) have great influence on tumor cell migration and invasion.

OBJECTIVES

The purpose of this study was to conduct an integrated analysis of miR expression in squamous cell carcinoma tissues with adequate or deficient serum folate. Further, study conducted tissue validation and functional analysis of miRs to uncover novel pathogenic mechanisms on the role of folate in squamous cell carcinoma (SCC).

MATERIALS AND METHODS

miR expression profiles were obtained from five paired primary SCC tumors with sufficient or deficient serum folate levels through Affymetrix GeneChip microRNA 4.0. This was followed by an integrated bioinformatics analysis and expanded sample size to verify core miRs by molecular biological validation. HeLa and SiHa cells with different concentrations of folate were used to clarify the roles of miR-27a on cell proliferation, migration, and invasion. MiR-27a expression was measured by the quantitative real-time polymerase chain reaction. Cell counting proliferation, wound healing, and transwell invasion assays were used to determine cell survival, proliferation, migration, and invasion abilities, respectively.

RESULTS

Our study found increasing miR-27a expression in serum of normal, high-grade squamous intraepithelial lesion (HSIL), and SCC tissues (in order of magnitude), which trend was negatively correlated with serum folate content. Further, there were significant differences in cellular miR-27a expression between 200 nM and 500 nM folate concentrations, with higher folate concentrations showing lower proliferation, migration, and invasion in SCC. Finally, miR-27a promoted proliferation and invasion in HeLa cells, whereas a miR-27a inhibitor blocked cell proliferation and invasion.

CONCLUSION

There is a significant association between miR-27a expression and folate during cervical carcinoma progression. Therefore, miR-27a could be used as a new biomarker for SCC diagnosis and prediction, suggesting a new therapeutic strategy for SCC treatment.

Blubber proteome response to repeated ACTH administration in a wild marine mammal

While the response to acute stress is adaptive in nature, repeated or chronic stress can impact an animal's fitness by depleting its energy stores and suppressing immune function and reproduction. This can be especially deleterious for species that rely on energy reserves to fuel key life history stages (e.g. reproduction), already experience physiological extremes (e.g. fasting), and/or have undergone significant population declines, such as many marine mammals. However, identifying chronically stressed individuals is difficult due to the practical challenges to sample collection from large aquatic animals and a paucity of information on downstream consequences of the stress response. We previously simulated repeated stress by ACTH administration in a model marine mammal, the northern elephant seal, and showed that changes in blubber gene expression, but not circulating cortisol levels, could distinguish between single and repeated responses to ACTH. Here, we profiled changes in the proteome of the same blubber cell population and identified a set of differentially expressed proteins that included extracellular matrix components, heat shock and mitochondrial proteins, metabolic enzymes, and metabolite transporters. Differentially expressed proteins and genes shared similar functions that suggest that repeated corticosteroid elevation may affect blubber tissue proteostasis, mitochondrial activity, adipogenesis, and metabolism in marine mammals. For marine mammal species from which blubber biopsies, but not blood can be obtained by remote sampling, measurement of abundance of such proteins may serve as a novel method for identifying chronically stressed animals.

UBE2C Is Upregulated by Estrogen and Promotes Epithelial-Mesenchymal Transition via p53 in Endometrial Cancer

Ubiquitin-conjugating enzyme E2C (UBE2C) plays important roles in tumor progression; nevertheless, its function in endometrial cancer remains unclear. This study elucidated the impact of UBE2C on endometrial cancer and its underlying mechanism. Human endometrial cancer and normal endometrial tissues were acquired from patients at Wuhan Union Hospital and UBE2C expression was detected by Western blotting and qRT-PCR. Endometrial cancer cells were transfected with a UBE2C overexpression plasmid or UBE2C-specific short hairpin RNA (shRNA) to up- or downregulate UBE2C expression, respectively. CCK8 and transwell assays were applied to assess the effects of UBE2C on cell proliferation, migration, and invasion. We found a significant elevation of UBE2C expression in patients with endometrial cancer, and that UBE2C upregulation was associated with advanced histologic grade, FIGO stage, recurrence, and shorter overall survival. UBE2C knockdown inhibited endometrial cancer cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT), whereas UBE2C overexpression exerted the opposite effects. UBE2C downregulation increased p53 and its downstream p21 expression, with p53 overexpression reversing the EMT-promoting effects of UBE2C. UBE2C enhanced p53 ubiquitination to facilitate its degradation in endometrial cancer cells. Estradiol (E2) induced UBE2C expression via estrogen receptor α, which binds directly to the UBE2C promoter element. Silencing of UBE2C inhibited E2-promoted migration, invasion, and EMT in vitro and in vivo. IMPLICATIONS: UBE2C-mediated tumor EMT promotion by estrogen is a novel mechanism for the progression of estrogen-induced endometrial cancer, which could offer new biomarkers for diagnosis and therapy of endometrial cancer in the future.

Crosstalk of intracellular post-translational modifications in cancer

Post-translational modifications (PTMs) have been reported to play pivotal roles in numerous cellular biochemical and physiological processes. Multiple PTMs can influence the actions of each other positively or negatively, termed as PTM crosstalk or PTM code. During recent years, development of identification strategies for PTMs co-occurrence has revealed abundant information of interplay between PTMs. Increasing evidence demonstrates that deregulation of PTMs crosstalk is involved in the genesis and development of various diseases. Insight into the complexity of PTMs crosstalk will help us better understand etiology and provide novel targets for drug therapy. In the present review, we will discuss the important functional roles of PTMs crosstalk in proteins associated with cancer diseases.

Ubiquitination status does not affect Vps34 degradation

Vps34 (vacuolar protein-sorting 34) plays important role in autophagy and endosomal trafficking. These processes are closely associated protein ubiquitination and degradation. We have hypothesized that Vps34 ubiquitination status would also control its degradation. Here, we report that our results did not support this assumption. In cells transiently transfected with ubiquitin (UB) constructs contained different lysine residues (Ks), Vps34 ubiquitination could occur regardless of the presence of any Ks in UB. However, Vps34 protein levels were not significantly altered in cells transiently transfected with these UB mutants. We further found that Vps34 protein was altered by pharmacological manipulation of E2/E3 activity; yet this effect was not significantly affected by UB overexpression. In vivo experiments revealed that in APP/PS1 mice, an animal model of Alzheimer's disease (AD), although ubiquitination of Vps34 was significantly reduced, Vps34 protein levels remained unchanged. Vps34 indeed was subjected to proteasomal or lysosomal degradation, as prolonged treatment of proteasomal inhibitor MG132 or lysosomal inhibitor chloroquine elevated Vps34 protein levels. We conclude that unlike most of other proteins, Vps34 ubiquitination is not closely associated with its degradation.

Hypoxia promotes colorectal cancer cell migration and invasion in a SIRT1-dependent manner

Background

Hypoxic microenvironments play a significant role in the progression of colorectal cancer (CRC). Silencing information regulator 1 (SIRT1), a class III histone deacetylase, modulates the multiple biological behaviors of cancer. However, its role in CRC remains unclear. This study aims to explore the role of SIRT1 in CRC migration and invasion under hypoxia.

Methods

SIRT1 protein and mRNA levels were detected by Western blotting and real-time PCR in CRC cells exposed to hypoxia (1% O₂). The migration and invasion abilities of SW480 and HCT116 cells with SIRT1 overexpression or knockdown were studied with transwell assays, and the results were confirmed by those of treatment with specific SIRT1 activator (SRT1720) and inhibitor (EX527). The dual-luciferase reporter systems with a series of SIRT1 promoter truncations were used to analyze their transcriptional activities, respectively. After a bioinformatic analysis of potential transcription factors, the direct interaction between the transcription factor and SIRT1 promoter was determined by chromatin immunoprecipitation (ChIP) assays. Western blot and real-time PCR assays were used to detect the activation and acetylation levels of the NF-κB pathway.

Results

The protein and mRNA levels of SIRT1 were significantly decreased under hypoxia, and these effects were replicated by cobalt chloride treatment. Hypoxia promoted cell migration and invasion, which were impeded by the overexpression or activation of SIRT1 and promoted by the knockdown or inhibition of SIRT1. The dual-luciferase reporter gene and ChIP analyses revealed that the core regulatory elements located 100 bp upstream of the SIRT1 promoter and early growth response factor 1 (EGR1) could interact with this DNA sequence. Subsequent rescue experiments suggested that EGR1 was essential for hypoxia-mediated SIRT1 transcriptional suppression. Western blot analyses demonstrated that SIRT1 overexpression eliminated the p65 acetylation induced by hypoxia along with the decreased MMP-2/-9, suggesting that NF-κB was a direct downstream target of SIRT1 and might regulate cell migration and invasion through MMP-2/-9.

Conclusions

Our results establish for the first time that EGR1 plays an important role in regulating SIRT1 expression under hypoxia. Hypoxia promotes CRC cell migration and invasion in a SIRT1-dependent manner. And a potential SIRT1/NF-κB/MMP-2/-9 axis modulates this process.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0819-9) contains supplementary material, which is available to authorized users.

Epigenetic-based therapy for colorectal cancer: Prospect and involved mechanisms

Epigenetic modifications are heritable variations in gene expression not encoded by the DNA sequence. According to reports, a large number of studies have been performed to characterize epigenetic modification during normal development and also in cancer. Epigenetics can be regarded more widely to contain all of the changes in expression of genes that make by adjusted interactions between the regulatory portions of DNA or messenger RNAs that lead to indirect variation in the DNA sequence. In the last decade, epigenetic modification importance in colorectal cancer (CRC) pathogenesis was demonstrated powerfully. Although developments in CRC therapy have been made in the last years, much work is required as it remains the second leading cause of cancer death. Nowadays, epigenetic programs and genetic change have pivotal roles in the CRC incidence as well as progression. While our knowledge about epigenetic mechanism in CRC is not comprehensive, selective histone modifications and resultant chromatin conformation together with DNA methylation most likely regulate CRC pathogenesis that involved genes expression. Undoubtedly, the advanced understanding of epigenetic-based gene expression regulation in the CRC is essential to make epigenetic drugs for CRC therapy. The major aim of this review is to deliver a summary of valuable results that represent evidence of principle for epigenetic-based therapeutic approaches employment in CRC with a focus on the advantages of epigenetic-based therapy in the inhibition of the CRC metastasis and proliferation.