SIRT1 promotes epithelial-mesenchymal transition and metastasis in colorectal cancer by regulating Fra-1 expression

TFF3 facilitates dormancy of anti-estrogen treated ER+ mammary carcinoma

BACKGROUND

Tumor dormancy is a substantial clinical obstacle in treatment of estrogen receptor positive mammary carcinoma (ER+MC), contributing to drug resistance, metastatic outgrowth, relapse, and consequent mortality.

METHODS

Preclinical models mimicking clinical anti-estrogen-induced ER+MC dormancy were generated in vivo. Function and a mechanism-based combination treatment were determined in the generated dormancy-like models in vitro, ex vivo, and in vivo.

RESULTS

The dormancy models display molecular features of dormancy and tumor mass and cellular dormancy with associated clinical dormancy behavior. Both serum and cancer tissue expression of Trefoil factor 3 (TFF3) are identified as prognostic indicators of dormant ER+MC with TFF3 functioning as an epigenetically regulated driver of dormancy-associated behaviors. BCL2-dependent pro-survival functions of TFF3 coupled with enhanced attributes of stemness designates TFF3 as an actionable target. Moreover, combination screening of a TFF3 small-molecule-inhibitor (AMPC) with compounds used clinically to treat anti-estrogen-resistant ER+MC identifies strong synergism between AMPC and CDK4/6 inhibitors in the dormancy-like models. The combination results in concomitant suppression of CCND1 expression and CDK4/6 kinase activity to decrease RB phosphorylation, with reduced BCL2 expression, leading to both ER + MC cell cycle arrest and apoptosis. The combined TFF3-CDK4/6 inhibition impedes metastatic outgrowth and ameliorates host animal survival in the dormancy-like models, producing a complete response in a percentage of animals.

CONCLUSIONS

Hence, in vivo models of anti-estrogen induced dormancy of ER+MC generated herein, identify TFF3 as a driver of this process. The combined inhibition of TFF3 and CDK4/6 may potentially alleviate the clinical challenges posed by anti-estrogen-induced dormancy in ER+MC.

Long non-coding RNA NEAT1 promotes colorectal cancer progression via interacting with SIRT1

Nuclear-enriched abundant transcript 1 (NEAT1), a long noncoding RNA, is found to be significantly dysregulated in different types of cancer, including colorectal cancer (CRC). Nevertheless, there is still much to learn about the precise functions and processes of NEAT1 in the progression of CRC. Using The Cancer Genome Atlas (TCGA) database and 50 CRC specimens from the First Affiliated Hospital of Dali University, we assessed the expression of NEAT1 to determine its clinical impact. Through gene set enrichment analysis (GSEA), Cancer Single-cell State Atlas (CancerSEA), and immune infiltration studies, we elucidated key functions of NEAT1. We utilized Cell Counting Kit-8 (CCK8), wound healing, and Transwell assays to investigate the role of NEAT1 in the progression of CRC. Through the use of GSEA and immunohistochemistry, additional investigations were conducted to unveil the downstream targets of NEAT1 and gain insights into their regulatory dynamics. Our in vitro studies confirmed the regulatory role of NEAT1 in CRC. Findings indicate that increased NEAT1 expression correlates with adverse outcomes in colorectal tissues. In the CRC model, reduced levels of NEAT1 lead to reduced cell proliferation, invasion, and migration. Additionally, NEAT1 influenced immune cell infiltration in CRC and functioned as an oncogene by upregulating Sirtuin 1 (SIRT1) expression. This study demonstrates that NEAT1 promotes CRC progression and metastasis through a SIRT1-mediated mechanism, suggesting its potential as a prognostic biomarker and therapeutic target for CRC.

Metabolic-Immune Suppression Mediated by the SIRT1-CX3CL1 Axis Induces Functional Enhancement of Regulatory T Cells in Colorectal Carcinoma

Metabolic reprogramming of tumor cells dynamically reshapes the distribution of nutrients and signals in the tumor microenvironment (TME), affecting intercellular interactions and resulting in metabolic immune suppression. Increased glucose uptake and metabolism are characteristic of many tumors. Meanwhile, the progression of colorectal carcinoma (CRC) relies on lipid metabolism. Therefore, investigating the role of glucolipid metabolic reprogramming on tumor immunity contributes to identifying new targets for immune suppression intervention in CRC. Our previous work demonstrated that SIRT1 is the hub gene involved in glucolipid metabolic conversion in CRC. Here, it is found that upregulated SIRT1 in CRC cells increases Treg functionality by promoting the secretion of CX3CL1. The CX3CL1-CX3CR1 signaling activated transcription factors SATB1 and BTG2, promoting the differentiation of TCF7+ Treg cells into functionally enhanced TNFRSF9+ Treg cells. Multiplex immunofluorescence (mIHC) analysis of a CRC tissue microarray confirmed the promoting effect of CX3CL1 on Treg infiltration. Additionally, the therapeutic efficacy of CX3CR1 inhibitor monotherapy and combination therapy is validated with the PD-1 antibody in the humanized subcutaneous CRC mouse model. This study elucidates a potential mechanism that metabolic reprogramming of cancer cells collaborates with subsequent immunosuppression to promote CRC progression.

Comprehensive analysis of the prognostic, immunological, and diagnostic roles of SIRT1 in pan-cancer and its validation in KIRC

Background

Disturbances in DNA damage repair may lead to cancer. SIRT1, an NAD+-dependent deacetylase, plays a crucial role in maintaining cellular homeostasis through the regulation of processes such as histone posttranslational modifications, DNA repair, and cellular metabolism. However, a comprehensive exploration of SIRT1's involvement in pan-cancer remains lacking. Our study aimed to analyze the role of SIRT1 in pan-cancer to gain a more comprehensive understanding of its role in multiple malignancies.

Methods

We systematically examined the role of SIRT1 in pan-cancer by analyzing data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Various tools, including R, Cytoscape, HPA, Archs4, TISIDB, cBioPortal, STRING, GSCALite, and CancerSEA, were used to integrate and analyze SIRT1 gene expression, prognosis, protein interactions, signaling pathways, immune infiltration, and other relevant information. Furthermore, we validated the differential expression of SIRT1 in normal human kidney cells and kidney cancer cell lines via experimental verification.

Results

SIRT1 expression was significantly reduced in various cancers and was different across molecular and immune subtypes. SIRT1 is intricately linked to numerous cancer pathways. In most cancer types, increased SIRT1 expression is positively associated with eosinophils, helper T cells, central memory T cells, effector memory T cells, γδ T cells, and Th2 cells. SIRT1 expression is significantly correlated with immune regulatory factors across various cancer types. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot (WB) analyses confirmed that SIRT1 is differentially expressed in kidney renal clear cell carcinoma (KIRC).

Conclusions

Using an integrative approach involving bioinformatics analysis and experimental validation, we clarified the potential roles and mechanisms of SIRT1 in pan-cancer, providing a theoretical basis for the development of SIRT1-targeted therapies in clinical applications.

SIRT1: a novel regulator in colorectal cancer

The class-III histone deacetylase SIRT1 is the most extensively investigated sirtuin deacetylase. It is resistant to the broad deacetylase inhibitor trichostatin A and depends on oxidized nicotinamide adenine nucleotide (NAD+). SIRT1 plays a crucial role in the tumorigenesis of numerous types of cancers, including colorectal cancer (CRC). Accumulating evidence indicates that SIRT1 is a therapeutic target for CRC; however, the function and underlying mechanism of SIRT1 in CRC still need to be elucidated. Herein, we provide a detailed and updated review to illustrate that SIRT1 regulates many processes that go awry in CRC cells, such as apoptosis, autophagy, proliferation, migration, invasion, metastasis, oxidative stress, resistance to chemo-radio therapy, immune evasion, and metabolic reprogramming. Moreover, we closely link our review to the clinical practice of CRC treatment, summarizing the mechanisms and prospects of SIRT1 inhibitors in CRC therapy. SIRT1 inhibitors as monotherapy in CRC or in combination with chemotherapy, radiotherapy, and immune therapies are comprehensively discussed. From epigenetic regulation to its potential therapeutic effect, we hope to offer novel insights and a comprehensive understanding of SIRT1's role in CRC.

SIRT1 silencing ameliorates malignancy of non-small cell lung cancer via activating FOXO1

Non-small cell lung cancer (NSCLC), being the most prevalent and lethal malignancy affecting the lungs, poses a significant threat to human health. This research aims at illustrating the precise role and related mechanisms of silent information regulator type-1 (SIRT1) in NSCLC progression. The expression pattern of SIRT1 in NSCLC cell lines was examined using quantitative real-time polymerase chain reaction and western blotting. Functional assays in NSCLC cell lines validated the biological capabilities of SIRT1 on malignant phenotypes, and its impact on tumorigenicity was further evaluated in vivo. In addition, the FOXO1 inhibitor AS1842856 was applied to verify the role of SIRT1 on FOXO pathway in vitro. SIRT1 expression was prominently elevated in NSCLC cell lines. The depletion of SIRT1 retarded the capabilities of proliferation, migration and invasion, while enhancing apoptosis in NSCLC cells. Furthermore, SIRT1 silencing restricted the tumorigenesis of NSCLC in vivo. Additionally, AS1842856 treatment ameliorated the inhibitory effect of SIRT1 deficiency on malignant phenotypes in NSCLC cells. SIRT1 deletion exerted an anti-oncogenic role in NSCLC via activation of FOXO1.

Novel role of lncRNAs regulatory network in papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most common endocrine malignancy. The incidence of PTC has increased annually worldwide. Thus, PTC diagnosis and treatment attract more attention. Noncoding RNAs (lncRNAs) play crucial roles in PTC progression and act as prognostic biomarkers. Moreover, microRNAs (miRNAs) and epithelial-mesenchymal transition (EMT)-associated proteins have potential biomarkers for diagnosing and treating PTC. However, the correlation of lncRNAs with miRNAs and EMT-associated proteins needs further clarification. The present review highlights the recent advances of lncRNAs in PTC. We significantly summarized the two molecular regulatory mechanisms in PTC progress, including lncRNAs-miRNAs-protein signaling axes and lncRNAs-EMT pathways. This review will help our understanding of the association between lncRNAs and PTC and may assist us in evaluating the prognosis for PTC patients. Taken together, targeting the lncRNAs regulatory network has promising applications in diagnosing and treating PTC.

SIRT1 mediates breast cancer development and tumorigenesis controlled by estrogen-related receptor β

Silent mating type information regulation 2 homolog 1 (SIRT1) is a class III histone deacetylase (HDAC) that is NAD + dependent and essential for metabolism, senescence, and cell survival. SIRT1 is overexpressed in several cancers, including breast cancer. SIRT1 is a well-known target gene of the estrogen receptor alpha (ER alpha) and is closely related to ER alpha deacetylation. Transcription factor Estrogen-related receptors (ERRs) share sequence homology with ERs in the DNA-binding domain, therefore, the possibility of sharing target genes between them is high. Our current research aims to gain insight into the function of ERRβ in regulating the activity of SIRT1 during the progression of breast cancer. ER-positive (ER + ve) breast cancer cells and tissues had considerably enhanced SIRT1 expression. Six potential ERRE sites were identified by analysis of the 5' upstream region of SIRT1, and both in vitro and in vivo experiments supported their presence. We found SIRT1 to be up-regulated in ERRβ overexpressed ER + ve breast cancer cells. Furthermore, our findings suggested that ectopic production of ERR and PCAF would increase SIRT1 activity. Our findings also indicated that ectopic production of ERRβ and PCAF increased SIRT1 activity. With sufficient evidence demonstrating the substantial involvement of SIRT1 in cell proliferation, migration, and colony formation capability, we were also able to illustrate the tumorigenic role of SIRT1. Overall, our findings highlight SIRT1's tumorigenic influence on breast cancer and suggest that SIRT1 inhibitors might serve as potential therapeutic drugs for the treatment of breast cancer.

Circ_0000370 Plays an Oncogenic Role in Colorectal Cancer by Regulating the miR-502-5p/SIRT1 Axis

The importance of circular RNA has been reported in cancer development. However, the role and mechanism of circ_0000370 in CRC progression are still unclear. Quantitative real-time PCR and Western blot assay were performed to measure RNA and protein expression. Cell proliferation was assessed by cell colony formation assay and 5-Ethynyl-2'-deoxyuridine assay. Flow cytometry was used to measure cell apoptosis. Cell migration and invasion were detected by transwell assay. The intermolecular target relations between miR-502-5p and circ_0000370 or SIRT1 were confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. A xenograft tumor model was established to examine the role of circ_0000370 in tumor growth in vivo. As compared with controls, the expression of circ_0000370 was upregulated in CRC tissues and cells. Circ_0000370 depletion inhibited CRC cell proliferation, migration and invasion but induced cell apoptosis. Meanwhile, circ_0000370 depletion restrained tumor growth in vivo. In addition, miR-502-5p inhibitor partly reverted the impacts of circ_0000370 knockdown on CRC cells. Moreover, miR-502-5p mimic-caused effects on cell phenotypes were attenuated by SIRT1 overexpression. Circ_0000370 induced the proliferation and metastasis of CRC cells by sponging miR-502-5p and enhancing SIRT1 expression, which provided a possible target for CRC treatment.

SIRT1 promotes the progression and chemoresistance of colorectal cancer through the p53/miR-101/KPNA3 axis

INTRODUCTION

Sirtuin 1 (SIRT1) is a key modulator in several types of cancer, including colorectal cancer (CRC). Here, we probed into the molecular mechanism of SIRT1 regulating the development and chemoresistance of CRC.

METHODS

Differentially expressed genes related to the growth, metastasis and chemoresistance of CRC were identified by bioinformatics analysis. The expression of SIRT1 in clinical tissues from CRC patients and CRC cell lines was detected by RT-qPCR. Interactions among SIRT1, p53, miR-101 and KPNA3 were analyzed. The effect of SIRT1 on the cell viability, migration, invasion, epithelial-mesenchymal transformation and chemoresistance to 5-FU was evaluated using loss-function investigations in CRC cells. Finally, a xenograft model of CRC and a metastasis model were constructed for further exploration of the roles of SIRT1 in vivo.

RESULTS

SIRT1 was elevated in CRC tissues and cell lines. SIRT1 decreased p53 via deacetylation, and consequently downregulated the expression of miR-101 while increasing that of the miR-101 target gene KPNA3. By this mechanism, SIRT1 enhanced the proliferation, migration, invasion, epithelial-mesenchymal transformation, and resistance to 5-FU of CRC cells. In addition, in vivo data also showed that SIRT1 promoted the growth, metastasis and chemoresistance to 5-FU of CRC cells via regulation of the p53/miR-101/KPNA3 axis.

CONCLUSIONS

In conclusion, SIRT1 can function as an oncogene in CRC by accelerating the growth, metastasis and chemoresistance to 5-FU of CRC cells through the p53/miR-101/KPNA3 axis.

Emerging therapeutic strategy for mitigating cancer progression through inhibition of sirtuin-1 and epithelial-mesenchymal transition

With 8.8 million deaths worldwide, cancer is the major reason for the high rate of fatalities. Malignancy's commencement, progression, development, metastasis, and therapy resistance have all been correlated with the epithelial-to-mesenchymal transition (EMT) pathway. EMT promotes the cancer cells' metastatic spread and starts the development of treatment resistance. Sirtuin-1 (SIRT1) is a histone deacetylase that is important for signaling, cell persistence, and apoptosis. It does this by deacetylating important cell signaling molecules and proteins that are associated with apoptosis. The function of SIRT1 in EMT and cancer progression, as well as the emerging therapeutic strategy of treating cancer through the inhibition of SIRT1 and EMT will be discussed in detail.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

Propofol inhibits colon cancer cell stemness and epithelial-mesenchymal transition by regulating SIRT1, Wnt/β-catenin and PI3K/AKT/mTOR signaling pathways

BACKGROUND

Propofol is a common sedative-hypnotic drug used for general anesthesia. Recent studies have drawn attention to the antitumor effects of propofol, but the potential mechanism by which propofol suppresses colon cancer stemness and epithelial-mesenchymal transition (EMT) has not been fully elucidated.

METHODS

For the in vitro experiments, we used propofol to treat LOVO and SW480 cells and Cell Counting Kit-8 (CCK-8) to detect proliferation. Self-renewal capacity, cell invasion and migration, flow cytometry analysis, qPCR and Western blotting were performed to detect the suppression of propofol to colon cancer cells and the underlying mechanism. Tumorigenicity and immunohistochemistry experiments were performed to confirm the role of propofol in vivo.

RESULT

We observed that propofol could suppressed stem cell-like characteristics and EMT-related behaviors, including self-renewal capacity, cell invasion and migration in colon cancer cells, and even suppressed tumorigenicity in vivo. Furthermore, investigations of the underlying mechanism revealed that propofol treatment downregulated SIRT1. SIRT1 overexpression or knockdown affected the stemness and EMT of colon cancer cells. Additionally, propofol reversed stemness and EMT in cells with overexpressing SIRT1 and subsequently inhibited the Wnt/β-catenin and PI3K/AKT/mTOR signaling pathways. Wnt/β-catenin pathway inhibitor and PI3K/AKT/mTOR pathway inhibitor blocked the propofol-induced reduction of sphere-formation and cell invasion-migration.

CONCLUSION

Propofol inhibits LOVO and SW480 cell stemness and EMT by regulating SIRT1 and the Wnt/β-catenin and PI3K/AKT/mTOR signaling pathways. Our findings indicate that propofol inhibits SIRT1 in cancer and is advantageous in colon cancer surgical treatment of patients with high SIRT1 expression.

NAD+ supplementation limits triple-negative breast cancer metastasis via SIRT1-P66Shc signaling

NAD⁺ levels decline with age and in certain disease conditions. NAD⁺ precursors have been shown to stimulate NAD⁺ biosynthesis and ameliorate various age-associated diseases in mouse models. However, NAD⁺ metabolism is complicated in cancer and its role in triple-negative breast cancer (TNBC) remains elusive. Here, we show that NAD⁺ supplement suppresses tumor metastasis in a TNBC orthotopic patient-derived xenograft (PDX) model. Sirtuin1 lysine deacetylase (SIRT1) is required for the effects since SIRT1 knockdown blocks NAD⁺-suppressed tumor metastasis. Overexpression of SIRT1 effectively impairs the metastatic potential of TNBC. Importantly, the interaction between SIRT1 and p66Shc causes the deacetylation and functional inactivation of p66Shc, which inhibits epithelial-mesenchymal transition (EMT). Overall, we demonstrate that NAD⁺ supplementation executes its anti-tumor function via activating the SIRT1-p66Shc axis, which highlights the preventive and therapeutic potential of SIRT1 activators as effective interventions for TNBC.

PUS7 promotes the proliferation of colorectal cancer cells by directly stabilizing SIRT1 to activate the Wnt/β-catenin pathway

Pseudouridine synthase 7 (PUS7) may play key roles in cancer development. However, few studies have been conducted in this area. In the present study, we explored the function and potential mechanisms of PUS7 in colorectal cancer (CRC) progression. We found that PUS7 had higher expression in CRC tissues and cell lines. Clinically, high expression of PUS7 was associated with an unfavorable prognosis for CRC patients. Functionally, knockdown of PUS7 suppressed the proliferation of CRC cells in vitro and inhibited tumorigenicity in vivo. Mechanistically, RNA sequencing and coimmunoprecipitation (Co-IP) indicated that PUS7 exhibited oncogenic functions through the interaction of Sirtuin 1 (SIRT1) and activated the Wnt/β-catenin signaling pathway. Thus, our findings suggest that PUS7 promotes the proliferation of CRC cells by directly stabilizing SIRT1 to activate the Wnt/β-catenin pathway.

Airborne particulate matter (PM10) induces cell invasion through Aryl Hydrocarbon Receptor and Activator Protein 1 (AP-1) pathway deregulation in A549 lung epithelial cells

BACKGROUND

Particulate matter with an aerodynamic size ≤ 10 μm (PM₁₀) is a risk factor for lung cancer development, mainly because some components are highly toxic. Polycyclic aromatic hydrocarbons (PAHs) are present in PM₁₀, such as benzo[a]pyrene (BaP), which is a well-known genotoxic and carcinogenic compound to humans, capable of activating AP-1 transcription factor family genes through the Aryl Hydrocarbon Receptor (AhR). Because effects of BaP include metalloprotease 9 (MMP-9) activation, cell invasion, and other pathways related to carcinogenesis, we aimed to demonstrate that PM₁₀ (10 µg/cm²) exposure induces the activation of AP-1 family members as well as cell invasion in lung epithelial cells, through AhR pathway.

METHODS AND RESULTS

The role of the AhR gene in cells exposed to PM₁₀ (10 µg/cm²) and BaP (1µM) for 48 h was evaluated using AhR-targeted interference siRNA. Then, the AP-1 family members (c-Jun, Jun B, Jun D, Fos B, C-Fos, and Fra-1), the levels/activity of MMP-9, and cell invasion were analyzed. We found that PM₁₀ increased AhR levels and promoted its nuclear localization in A549 treated cells. Also, PM₁₀ and BaP deregulated the activity of AP-1 family members. Moreover, PM₁₀ upregulated the secretion and activity of MMP-9 through AhR, while BaP had no effect. Finally, we found that cell invasion in A549 cells exposed to PM₁₀ and BaP is modulated by AhR.

CONCLUSION

Our results demonstrated that PM₁₀ exposure induces upregulation of the c-Jun, Jun B, and Fra-1 activity, the expression/activity of MMP-9, and the cell invasion in lung epithelial cells, effects mediated through the AhR. Also, the Fos B and C-Fos activity were downregulated. In addition, the effects induced by PM₁₀ exposure were like those induced by BaP, which highlights the potentially toxic effects of the PM₁₀ mixture in lung epithelial cells.

Proteomics approaches to characterize the immune responses in cancer

Despite the dynamic development of cancer research, annually millions of people die of cancer. The human immune system is the major 'guard' against tumor development. Unfortunately, cancer cells have the ability to evade the immune system and continue to grow. The proper understanding of the intricate immune response in tumorigenesis remains the holy grail of cancer immunology and designing effective immunotherapy. To decode the immune responses in cancer, in recent years, proteomics studies have received considerable attention. Proteomics studies focus on the detection and quantification of proteins, which are the effectors of biological functions, and as such, are proven to reflect the cell state more accurately, in comparison to genomic or transcriptomic studies. In this review, we discuss the proteomics studies applied to characterize the immune responses in cancer and tumor immune microenvironment heterogeneity. Further, we describe emerging single-cell proteomics approaches that have the potential to be applied in cancer immunity studies.

Autophagy: A Versatile Player in the Progression of Colorectal Cancer and Drug Resistance

Colorectal cancer (CRC) is among the topmost malignancies for both genders. Despite the high incidence rate and advances in diagnostic tools, treatment in many cases is still ineffective. Most cancerous lesions in CRC begin as benign, followed by the development of invasive forms and metastases. The development of CRC has been linked to defects in autophagy, which plays both a pro-and anti-tumor role and is mainly context-dependent. Autophagy suppression could enhance apoptosis via p53 activation, or autophagy also promotes tumor progression by maintaining tumor growth and increasing resistance to chemotherapy. Autophagy promotes the invasion and metastasis of CRC cells via increased epithelial-mesenchymal transition (EMT). Moreover, dysbiosis of gut microbiota upregulated autophagy and metastasis markers. Autophagy responses may also modulate the tumor microenvironment (TME) via regulating the differentiation process of several innate immune cells. Treatments that promote tumor cell death by stimulating or inhibiting autophagy could be beneficial if used as an adjunct treatment, but the precise role of various autophagy-modulating drugs in CRC patients is needed to be explored. In this article, we present an overview of the autophagy process and its role in the pathogenesis and therapeutic resistance of CRC. Also, we focused on the current understanding of the role of the EMT and TME, including its relation to gut microbiota and immune cells, in autophagic manipulation of CRC. We believe that there is a potential link between autophagy, TME, EMT, and drug resistance, suggesting that further studies are needed to explore this aspect.

FRA-1: A key factor regulating signal transduction of tumor cells and a potential target molecule for tumor therapy

Fos-related antigen-1 (FRA-1) is a member of activator protein-1 (AP-1) transcription factor superfamily, and FRA-1 is highly expressed in colon cancer, breast cancer, gastric cancer, lung cancer, bladder cancer, and other tumors. The expression level of FRA-1 is closely related to the processes of tumor cell proliferation, apoptosis, transformation, migration, and invasion, which is a potential therapeutic target and prognostic factor for many tumors. Clarifying the detailed mechanism of action of FRA-1 could provide the theoretical basis for tumor diagnosis, treatment, and prognosis, and is of great significance for the study of tumor etiology and pathogenesis. In this paper, the expression levels and influencing factors of FRA-1 in various tumor tissues and cells are summarized, as well as the effect of FRA-1 expression level on the biological behavior of tumor cells and the signal transduction mechanism. At the same time, the signal transduction mechanism of FRA-1 in inflammation was expounded. In addition, the related metabolites, drugs and non-coding RNA that affect the expression and function of FRA-1 were summarized. Finally, it illustrates that FRA-1 may be taken as a key factor for tumor prognosis and a potential therapeutic target. This review provides a theoretical basis for the systematic understanding of the relationship between FRA-1 and tumors, its function, and possible mechanism.

The role of epigenetic modifications in Colorectal Cancer Metastasis

Distant metastasis is the major contributor to the high mortality rate of colorectal cancer (CRC). To overcome the poor prognosis caused by distant metastasis, the mechanisms of CRC metastasis should be further explored. Epigenetic events are the main mediators of gene regulation and further affect tumor progression. Recent studies have found that some epigenetic enzymes are often dysregulated or mutated in multiple tumor types, which prompted us to study the roles of these enzymes in CRC metastasis. In this review, we summarized the alteration of enzymes related to various modifications, including histone modification, nonhistone modification, DNA methylation, and RNA methylation, and their epigenetic mechanisms during the progression of CRC metastasis. Existing data suggest that targeting epigenetic enzymes is a promising strategy for the treatment of CRC metastasis.

Enhanced autophagy promotes radiosensitivity by mediating Sirt1 downregulation in RM-1 prostate cancer cells

Autophagy is a double-edged sword that affects tumor progression by promoting cell survival or death depending on different living contexts. The concrete mechanism by which autophagy modulates the efficacy of radiotherapy for prostate cancer (PC) remains unclear. We exposed RM-1 PC cells to X-ray and explored the role of autophagy in radiation injury. Our results showed increased apoptosis and autophagy levels in RM-1 cells after radiation. Pharmacological inhibition of autophagy by chloroquine significantly mitigated radiation-induced apoptosis, while the enhancement of autophagy by rapamycin aggravated apoptosis. Sirt1, a member of sirtuin family, deacetylates various transcription factors to trigger cell survival in response to radiation injury. We found that radiation led to Sirt1 downregulation, which was reversed by the inhibition of autophagy. On the contrary, enhanced autophagy further diminished protein level of Sirt1. Notably, overexpression of Sirt1 by plasmid significantly alleviated radiation-induced apoptosis, but silenced Sirt1 by siRNA further induced apoptosis, indicating the radioprotective effect of Sirt1 on RM-1 cells. In summary, our findings suggested that autophagy-mediated Sirt1 downregulation might be a promising therapeutic target for PC.

Trefoil factor 3 promotes pancreatic carcinoma progression via WNT pathway activation mediated by enhanced WNT ligand expression

Pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer-related mortality with a dismal prognosis that has changed little over the past few decades. Further understanding of the molecular pathology of PDAC progression is urgently required in order to improve the prognosis of patients with PDAC. Herein, it was observed that trefoil factor 3 (TFF3) expression was elevated in PDAC, and was positively correlated with a worse overall patient survival outcome. Forced expression of TFF3 promoted oncogenic functions of PDAC cells in vitro including cell proliferation, survival, foci formation, cancer stem cell-like behavior and invasion, ex vivo colony growth in 3D-Matrigel, and xenograft growth in vivo. Depletion or pharmacological inhibition of TFF3 inhibited these same processes. RNA-Seq analysis and subsequent mechanistic analyses demonstrated that TFF3 increased the expression of various WNT ligands to mediate WNT pathway activation required for TFF3-stimulated PDAC progression. Combined pharmacological inhibition of TFF3 and WNT signaling significantly attenuated PDAC xenograft growth and potentiated the therapeutic efficacy of gemcitabine in both ex vivo and in vivo models. Hence, a mechanistic basis for combined inhibition of pathways enhancing PDAC progression is provided and suggests that inhibition of TFF3 may assist to ameliorate outcomes in PDAC.

Melatonin Inhibits EMT and PD-L1 Expression through the ERK1/2/FOSL1 Pathway and Regulates Anti-Tumor Immunity in HNSCC

Melatonin is an endogenous hormone with various biological functions and possesses anti-tumor properties in multiple malignancies. Immune evasion is one of the most important hallmarks of head and neck squamous cell carcinoma (HNSCC) and is closely related to tumor progression. However, as an immune modulator under physiological conditions, the roles of melatonin in tumor immunity in HNSCC remains unclear. In this study, we found that the endogenous melatonin levels in HNSCC patients were lower than those in patients with benign tumors in head and neck. Importantly, lower melatonin levels were related to lymph node metastasis among HNSCC patients. Moreover, melatonin significantly suppressed programmed death-ligand 1 (PD-L1) expression and inhibited epithelial-mesenchymal transition (EMT) of HNSCC through the ERK1/2/FOSL1 pathway in vitro and vivo. In SCC7/C3H syngeneic mouse models, anti-programmed death-1 (PD-1) antibody combined with melatonin significantly inhibited tumor growth and modulated anti-tumor immunity by increasing CD8⁺ T cell infiltration and decreasing regulatory T cell (Treg) proportion in tumor microenvironment. Taken together, melatonin inhibited EMT and downregulated PD-L1 expression in HNSCC through the ERK1/2/FOSL1 pathway and exerted synergistic effects with anti-PD-1 antibody in vivo, which could provide promising strategies for HNSCC treatment.

NRG1 regulates Fra-1 transcription and metastasis of triple-negative breast cancer cells via the c-Myc ubiquitination as manipulated by ERK1/2-mediated Fbxw7 phosphorylation

Neuregulin 1 (NRG1), an EGF family member, is expressed in most breast cancers. It promotes breast cancer growth and metastasis in HER2 receptor expressing breast cancer. However, its role in triple-negative breast cancer (TNBC) has not been extensively investigated. In this study, we observed that NRG1 knockdown resulted in the suppression of TNBC cells (MDA-MB-231 cell and MDA-MB-468 cell) metastasis and downregulation of Fra-1 (FOS-like 1, AP-1 transcription factor subunit, which is an overexpressed transcription factor in TNBC and acts as a coordinator of metastasis). In addition, the transcriptional regulation of Fra-1 by NRG1 was mediated by ERK1/2-induced recruitment of c-Myc (MYC proto-oncogene, transcription factor) to the promoter of Fra-1. Furthermore, c-Myc was targeted by an E3 ligase Fbxw7 and its ubiquitination and degradation by Fbxw7 was regulated by NRG1 expression and ERK1/2-mediated Fbxw7 phosphorylation that results in the dissociation and nuclear import of c-Myc. Taken together, the results of our study demonstrated that NRG1 regulates the Fra-1 expression to coordinate the TNBC metastasis via the novel ERK1/2-Fbxw7-c-Myc pathway and targeting NRG1 expression could be a potential therapeutic strategy for TNBC.

LncRNA UCA1 mediates Cetuximab resistance in Colorectal Cancer via the MiR-495 and HGF/c-MET Pathways

Background: Cetuximab is one of the most widely used monoclonal antibodies to treat patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC). Unfortunately, cetuximab resistance often occurs during targeted therapy. However, the underlying epigenetic mechanisms remain unclear. Our previous study demonstrated that the exosomal transfer of urothelial carcinoma-associated 1 (UCA1) confers cetuximab resistance to CRC cells. The goal of this study was to elucidate the detailed role of UCA1 in cetuximab resistance in CRC and the underlying molecular mechanism.

Methods:In vitro and in vivo functional studies were performed to assess the role of UCA1 in cetuximab resistance in CRC cell lines and xenograft models. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to examine UCA1 localization and expression. Bioinformatics analysis was performed to predict the potential mechanism of UCA1, which was further validated by the dual-luciferase reporter assay and the RNA immunoprecipitation (RIP) assay. Cells treated with indicators were subjected to Cell Counting Kit-8 (CCK-8) and western blotting to investigate the role of hepatocyte growth factor (HGF)/c-mesenchymal-epithelial transition (c-MET) signalling in UCA1-mediated cetuximab resistance.

Results: We showed that UCA1 decreased CRC cell sensitivity to cetuximab by suppressing apoptosis. Mechanistic studies revealed that UCA1 promoted cetuximab resistance by competitively binding miR-495 to facilitate HGF and c-MET expression in CRC cells. Moreover, HGF was shown to attenuate the cetuximab-induced inhibition of cell proliferation by activating the HGF/c-MET pathway in CRC cells.

Conclusion: We provide the first evidence of a UCA1-miR-495-HGF/c-MET regulatory network involved in cetuximab resistance in CRC. Therefore, UCA1 has potential as a predictor and therapeutic target for cetuximab resistance.

Common Pathogenetic Mechanisms Underlying Aging and Tumor and Means of Interventions

Recently, there has been an increase in the incidence of malignant tumors among the older population. Moreover, there is an association between aging and cancer. During the process of senescence, the human body suffers from a series of imbalances, which have been shown to further accelerate aging, trigger tumorigenesis, and facilitate cancer progression. Therefore, exploring the junctions of aging and cancer and searching for novel methods to restore the junctions is of great importance to intervene against aging-related cancers. In this review, we have identified the underlying pathogenetic mechanisms of aging-related cancers by comparing alterations in the human body caused by aging and the factors that trigger cancers. We found that the common mechanisms of aging and cancer include cellular senescence, alterations in proteostasis, microbiota disorders (decreased probiotics and increased pernicious bacteria), persistent chronic inflammation, extensive immunosenescence, inordinate energy metabolism, altered material metabolism, endocrine disorders, altered genetic expression, and epigenetic modification. Furthermore, we have proposed that aging and cancer have common means of intervention, including novel uses of common medicine (metformin, resveratrol, and rapamycin), dietary restriction, and artificial microbiota intervention or selectively replenishing scarce metabolites. In addition, we have summarized the research progress of each intervention and revealed their bidirectional effects on cancer progression to compare their reliability and feasibility. Therefore, the study findings provide vital information for advanced research studies on age-related cancers. However, there is a need for further optimization of the described methods and more suitable methods for complicated clinical practices. In conclusion, targeting aging may have potential therapeutic effects on aging-related cancers.

Insight Into Nicotinamide Adenine Dinucleotide Homeostasis as a Targetable Metabolic Pathway in Colorectal Cancer

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H).

circ-SIRT1 Promotes Colorectal Cancer Proliferation and EMT by Recruiting and Binding to eIF4A3

Circular RNA (circRNA), a recently identified type of endogenous noncoding RNA, has been implicated in the occurrence and development of a variety of tumors; however, whether circ-SIRT1, derived from pre-mRNA of the parental SIRT1 gene, is involved in colorectal cancer (CRC) remains unknown, as do the potential underlying mechanisms. The expression of circ-SIRT1 in CRC cells and tissue was detected by RT-qPCR. Colony formation and Cell Counting Kit-8 assays were used to evaluate the effect of circ-SIRT1 knockdown on the proliferative ability of CRC cells. Wound healing and Transwell assays were used to assess the effect of circ-SIRT1 knockdown on the migratory and invasive capacity of CRC cells. RNA immunoprecipitation and RNA pull-down assays were employed to validate the binding of circ-SIRT1 to EIF4A3. Western blot was used to identify the changes in the expression of EIF4A3 and EMT-related proteins. The RT-qPCR results showed that circ-SIRT1 was highly expressed in CRC cells and tissue and was positively correlated with the depth of tumor invasion. Knocking down circ-SIRT1 inhibited the proliferation and invasion of CRC cells and EMT. We further found that EIF4A3 could bind to circ-SIRT1, and that overexpressing circ-SIRT1 decreased the abundance of EIF4A3 at the mRNAs of the EMT marker proteins N-cadherin and vimentin. Combined, our findings suggested that circ-SIRT1 regulates the expression of EMT-related proteins by preventing EIF4A3 recruitment to the respective mRNAs. Our results further indicate that circ-SIRT1 functions as an oncogene in CRC by promoting the proliferation, invasion, and EMT of CRC cells through the circ-SIRT1/EIF4A3/N-cadherin/vimentin pathway.

FBXW11 contributes to stem-cell-like features and liver metastasis through regulating HIC1-mediated SIRT1 transcription in colorectal cancer

Colorectal tumorigenesis is a heterogeneous disease driven by multiple genetic and epigenetic alterations. F-box and WD repeat domain containing 11 (FBXW11) is a member of the F-box protein family that regulates the ubiquitination of key factors associated with tumor growth and aggressiveness. Our study aimed to explore the role of FBXW11 in the development and metastasis of colorectal cancer (CRC). FBXW11 was overexpressed in colorectal tumor tissues and its overexpression was associated with a poor prognosis of CRC patients. The upregulation of FBXW11 not only promoted cell proliferation, invasion, and migration, but also contributed to maintaining stem-cell features in colorectal tumor cells. Further analysis revealed that FBXW11 targeted hypermethylated in cancer 1 (HIC1) and reduced its stability in CRC cells through ubiquitination. Moreover, the expression of sirtuin 1 (SIRT1), a deacetylase in tumor cells was upregulated by FBXW11 via regulating HIC1 expression. The mouse xenograft models of CRC confirmed that FBXW11 knockdown impeded colorectal tumor growth and liver metastasis in vivo. In summary, our study identified FBXW11 as an oncogenic factor that contributed to stem-cell-like properties and liver metastasis in CRC via regulating HIC1-mediated SIRT1 expression. These results provide a rationale for the development of FBXW11-targeting drugs for CRC patients.

Characterization of Histone Deacetylase Mechanisms in Cancer Development

Over decades of studies, accumulating evidence has suggested that epigenetic dysregulation is a hallmark of tumours. Post-translational modifications of histones are involved in tumour pathogenesis and development mainly by influencing a broad range of physiological processes. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are pivotal epigenetic modulators that regulate dynamic processes in the acetylation of histones at lysine residues, thereby influencing transcription of oncogenes and tumour suppressor genes. Moreover, HDACs mediate the deacetylation process of many nonhistone proteins and thus orchestrate a host of pathological processes, such as tumour pathogenesis. In this review, we elucidate the functions of HDACs in cancer.

BZD9L1 sirtuin inhibitor: Identification of key molecular targets and their biological functions in HCT 116 colorectal cancer cells

BZD9L1 was previously described as a SIRT1/2 inhibitor with anti-cancer activities in colorectal cancer (CRC), either as a standalone chemotherapy or in combination with 5-fluorouracil. BZD9L1 was reported to induce apoptosis in CRC cells; however, the network of intracellular pathways and crosstalk between molecular players mediated by BZD9L1 is not fully understood. This study aimed to uncover the mechanisms involved in BZD9L1-mediated cytotoxicity based on previous and new findings for the prediction and identification of related pathways and key molecular players. BZD9L1-regulated candidate targets (RCTs) were identified using a range of molecular, cell-based and biochemical techniques on the HCT 116 cell line. BZD9L1 regulated major cancer pathways including Notch, p53, cell cycle, NFκB, Myc/MAX, and MAPK/ERK signalling pathways. BZD9L1 also induced reactive oxygen species (ROS), regulated apoptosis-related proteins, and altered cell polarity and adhesion profiles. In silico analyses revealed that most RCTs were interconnected, and were involved in the modulation of catalytic activity, metabolism and transcription regulation, response to cytokines, and apoptosis signalling pathways. These RCTs were implicated in p53-dependent apoptosis pathway. This study provides the first assessment of possible associations of molecular players underlying the cytotoxic activity of BZD9L1, and establishes the links between RCTs and apoptosis through the p53 pathway.

Trending topics of SIRT1 in tumorigenicity

BACKGROUND

Carcinogenesis is governed by a series of genetic alterations and epigenetic changes that lead to aberrant patterns in neoplastic cells. Sirtuin-1(SIRT1), an NAD⁺-dependent protein deacetylase, is capable of deacetylating histones and non-histone substrates that regulate various physiological activities during tumorigenesis. Recent studies have identified the role of SIRT1 in different stages of cancer, including genome instability, tumor initiation, proliferation, metabolism, and therapeutic response. However, the action of SIRT1 has been reported to be both oncogenic and tumor suppressive during carcinogenesis. Consequently, the biological functions of SIRT1 in cancer remain controversial.

SCOPE OF REVIEW

We highlight the most recent findings on SIRT1 in different stages of tumorigenesis, and update the current status of SIRT1 small molecule modulators in clinical application of cancer treatment.

MAJOR CONCLUSION

By targeting both tumor suppressors and oncogenic proteins, SIRT1 has a bifunctional role at different stages of tumorigenesis. The impact of SIRT1 on tumorigenesis is also distinct at different stages and is dependent on its dosages. SIRT1 suppresses tumor initiation through its functions in promoting DNA repair, increasing genome stability, and inhibiting inflammation at the pre-cancer stage. However, SIRT1 enhances tumor proliferation, survival, and drug resistance through its roles in anti-apoptosis, pro-tumor metabolism, and anti-inflammation (inhibition of anti-tumor immunity) at the stages of tumor progression, metastasis, and relapse. Consequently, both SIRT1 inhibitors and activators have been explored for cancer treatment.

GENERAL SIGNIFICANCE

Better understanding the dose- and stage-dependent roles of SIRT1 in each cancer type can provide new avenues of exploration for therapy development.

Targeting Sirtuin 1 signaling pathway by ginsenosides

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng is a kind of traditional Chinese herbal medicine, known as "king of herbs" and widely used in China, South Korea, and other Asian countries. Ginsenosides are one of active components of Panax ginseng Meyer, which have many pharmacological effects, such as enhancing memory, improving immunity and cardiovascular system, delaying aging, and preventing cancer.

AIMS OF THE REVIEW

This review aims to summarize the recent findings for ginsenosides targeting Sirtuin 1 (SIRT1) signaling pathway for the prevention and treatment of a series of diseases.

MATERIALS AND METHODS

An up-to-August 2020 search was carried out in databases such as PubMed, ScienceDirect, Google Scholar, China National Knowledge Infrastructure, and classic books of traditional Chinese medicine using the keywords: "SIRT1", and/or paired with "ginseng", and "ginsenosides".

RESULTS

SIRT1 is a class-III histone deacetylase (HDAC), a nicotinamide adenine dinucleotide (NAD⁺)-dependent enzyme, which is deeply involved in a series of pathological processes. Based on specific intracellular localization, SIRT1 has various cytoplasmic and nuclear targets and plays a potential role in energy metabolism, oxidative stress, inflammation, tumorigenesis, and aging. Ginsenosides are generally classified into three groups and microbially transformed to final metabolites. Among of them, most ginsenosides have been reported as SIRT1 activators, especially those ginsenosides with two glucopyranosyl groups on the C-3 position. Importantly, many ginsenosides can be used to prevent and treat oxidative stress, inflammation, aging, tumorigenesis, depression, and others by targeting SIRT1 signaling pathway.

CONCLUSIONS

This paper reviews recent evidences of ginsenosides targeting SIRT1 for the first time, which could provide new insights on the preclinical and clinical researches for ginsenosides against multiple disorders.

Upregulation of mir-132 induces dopaminergic neuronal death via activating SIRT1/P53 pathway

For several neurodegenerative disorders, including Parkinson's Disease (PD) and Alzheimer's Disease (AD), microRNAs (miRNAs) have been known to play a crucial role. So, in this study miR-132 and its role in PD cell models was investigated. We wanted to investigate the survival or death pathway involved in PD. We observed the expression levels of miR-132 in MPP+ - treated SH-SY5Y cell line, which acted as a PD cell model, and found an increased expression of miR-132. Moreover, through the Dual-Luciferase® Reporter (DLR™) Assay, it was also revealed that miR-132 targets SIRT1 3'UTR, a histone deacetylase, and decreases its activity, which results in increased acetylation of p53, an apoptotic inducer. p53 acetylation leads to overexpression of other pro-apoptotic genes like Puma and Noxa, which eventually leads to cell death. Here, we show that the upregulation of miR-132 in SH-SY5Y cells can induce apoptosis through the SIRT1/p53 pathway.

MiR-140 Resensitizes Cisplatin-Resistant NSCLC Cells to Cisplatin Treatment Through the SIRT1/ROS/JNK Pathway

Background

Although cisplatin is an effective chemotherapeutic drug that is commonly used for non-small-cell lung cancer (NSCLC) treatment, the drug resistance usually occurs during the long-term use of it. It is urgent to develop strategies to reduce the resistance of NSCLC cells to cisplatin.

Methods

Cisplatin-resistant NSCLC cell lines (PC9/R and A549/R) were acquired through long-term exposure of PC9 and A549 cells to cisplatin. QRT-PCR analysis was performed to compare the expression of miR-140 between routine NSCLC cells and cisplatin-resistant NSCLC cells. CCK-8 assay was used to evaluate the effect of miR-140 on the sensitivity of PC9/R and A549/R to cisplatin. Western blot assay and luciferase reporter assay were used to confirm the regulation of miR-140 on SIRT1. Western blot and flow cytometry analysis were performed to evaluate the effect of miR-140 on the apoptosis pathway induced by cisplatin.

Results

PC9/R and A549/R exhibited obviously lower sensitivity compared to their parental PC9 and A549 cells, respectively. Furthermore, PC9/R and A549/R cells expressed significantly lower levels of miR-140 compared to their parental PC9 and A549 cells, respectively. However, transfection with miR-140 mimics significantly resensitized the PC9/R and A549/R to cisplatin-induced cytotoxicity. In the mechanism research, we confirmed that SIRT1 was overexpressed and was targeted by miR-140 in PC9/R and A549/R. Furthermore, overexpression of SIRT1 was responsible for the resistance to cisplatin in PC9/R and A549/R cells. Transfection with miR-140 was able to inhibit the expression of SIRT1 and thus inhibited the SIRT1/ROS/JNK pathway. As a result, the PC9/R and A549/R cells restored the sensitivity to cisplatin-induced apoptosis.

Conclusion

MiR-140 resensitizes cisplatin-resistant NSCLC cells to cisplatin treatment through the SIRT1/ROS/JNK pathway.

MiR-124 sensitizes cisplatin-induced cytotoxicity against CD133+ hepatocellular carcinoma cells by targeting SIRT1/ROS/JNK pathway

Drug resistance is still a major obstacle for efficient treatment of hepatocellular carcinoma (HCC) during the cisplatin-based chemotherapy. Recent studies have demonstrated that CD133 positive population of cancer cells are responsible for multiple drug resistance. We are supposed to take strategies to sensitize CD133⁺ HCC cells to cisplatin treatment. In the present study, CD133⁺ HCC cells showed significant cisplatin-resistance compared to the CD133^- HCC cells. Downregulation of miR-124 was observed in CD133⁺ HCC cells. However, enforced expression of miR-124 can increase the sensitivity of CD133⁺ HCC cells to cisplatin treatment in vitro and in vivo. Mechanically, overexpression of miR-124 was found to inhibit the expression of SIRT1 and thus promoted the generation of ROS and phosphorylation of JNK. As the results, overexpression of miR-124 expanded the apoptosis in cisplatin-treated CD133⁺ HCC cells. We then demonstrated that overexpression of miR-124 sensitized cisplatin-induced cytotoxicity against CD133⁺ hepatocellular carcinoma cells by targeting SIRT1/ROS/JNK pathway.

Natural SIRT1 modifiers as promising therapeutic agents for improving diabetic wound healing

BACKGROUND

The occurrence of chronic wounds, account for significant suffering of diabetic people, together with increasing healthcare burden. The chronic wounds associated with diabetes do not undergo the normal healing process rather stagnate into chronic proinflammatory phase as well as declined fibroblast function and impaired cell migration.

HYPOTHESIS

SIRT1, which is the most studied isoform of the sirtuin family in mammals, has now emerged as a crucial target for improving diabetic wound healing. It is an NAD+ dependent deacetylase, originally characterized to deacetylate histone proteins leading to heterochromatin formation and gene silencing. It is now known to regulate a number of cellular processes like cell proliferation, division, senescence, apoptosis, DNA repair, and metabolism.

METHODOLOGY

The retrieval of potentially relevant studies was done by systematically searching of three databases (Google Scholar, Web of science and PubMed) in December 2019. The keywords used as search terms were related to SIRT1 and wound healing. The systematic search retrieved 649 papers that were potentially relevant and after selection procedure, 73 studies were included this review and discussed below.

RESULTS

Many SIRT1 activating compounds (SACs) were found protective and improve diabetic wound healing through regulation of inflammation, cell migration, oxidative stress response and formation of granulation tissue at the wound site.

CONCLUSIONS

However, contradictory reports describe the opposing role of SACs on the regulation of cell migration and cancer incidence. SACs are therefore subjected to intense research for understanding the mechanisms responsible for controlling cell migration and therefore possess prospective to enter the clinical arena in the foreseeable future.

The nuclear oncoprotein Fra-1: a transcription factor knocking on therapeutic applications' door

Among the FOS-related members of the AP-1 dimeric complex, the transcription factor Fra-1, encoded by FOSL1, is crucially involved in human tumor progression and metastasis, thus representing a promising therapeutic target. Here we review the state of the art and discuss the emerging topics and perspectives on FOSL1 and its gene product. First, we summarize the present knowledge on the FOSL1 transcriptional and epigenetic controls, driving Fra-1 accumulation in a variety of human solid tumors. We also present a model on the regulatory interactions between Fra-1, p53, and miRNAs. Then, we outline the multiple roles of Fra-1 posttranslational modifications and transactivation mechanisms of select Fra-1 target genes. In addition to summarizing the Fra-1-dependent gene networks controlling proliferation, survival, and epithelial-mesenchymal transitions (EMT) in multiple cancer cell types, we highlight the roles played by Fra-1 in nonneoplastic cell populations recruited to the tumor microenvironment, and in mouse models of tumorigenesis. Next, we review the prognostic power of the Fra-1-associated gene signatures, and envisage potential strategies aimed at Fra-1 therapeutic inhibition. Finally, we discuss several recent reports showing the emerging roles of Fra-1 in the mechanisms of both resistance and addiction to targeted therapies.

Ubiquitination-mediated degradation of SIRT1 by SMURF2 suppresses CRC cell proliferation and tumorigenesis

The NAD-dependent deacetylase sirtuin 1 (SIRT1), a member of the mammalian sirtuin family, plays a pivotal role in deacetylating histone and nonhistone proteins. Recently, it has been reported that SIRT1 is upregulated in various kinds of tumors and is associated with cell growth and metastasis. However, the factors and molecular mechanism regulating its cellular levels remain to be clarified. Here, we reported that the E3 ubiquitin ligase SMURF2 interacts with SIRT1 and mediates its ubiquitination and degradation. Depletion of SMURF2 leads to SIRT1 upregulation and induces the tumor formation and growth of colorectal cancer in vitro and in vivo. Furthermore, we show a negative correlation between SIRT1 and SMURF2 expression in human colorectal cancer. Thus, we propose a novel mechanism of colorectal tumorigenesis via SIRT1 regulation by SMURF2, which could potentially give rise to a new strategy for the treatment of colorectal cancer.

Long noncoding RNA-GAS5 attenuates progression of glioma by eliminating microRNA-10b and Sirtuin 1 in U251 and A172 cells

Long noncoding RNA (lncRNA) growth arrest-specific 5 (GAS5) is implicated in several cancers via modulating microRNAs (miRs). However, little information is available about the correlation between GAS5 and miR-10b. Therefore, we sought out to investigate the biological role of GAS5-miR-10b node mainly in glioma cells. We artificially modulated GAS5 to explore its roles in viability assayed by cell counting kit-8 (CCK-8), motile activities by 24-Transwell assay, as well as apoptosis by a flow cytometer and Western blot assay. miR-10b and Sirtuin 1 (Sirt1) were quantified by qRT-PCR. After co-transfection, we analyzed the viability, migration, invasion, apoptosis, and Sirt1 expression. Western blot was implemented to detect the phosphorylated forms of PTEN, PI3K, AKT, MEK, and ERK. GAS5 inhibited proliferation and motile behaviors, and fortified apoptosis. As for the viability and motile activities, the property of GAS5 was reversed in miR-10b-replenished U251 and A172 cells, while maintained in miR-10b-deficient cells. Additionally, GAS5-induced apoptosis was abolished by miR-10b overexpression while fortified by miR-10b silence. Besides, GAS5 negatively modulated Sirt1 via miR-10b. Moreover, Sirt1 negatively modulated PTEN and positively mediated the abovementioned regulators. GAS5 represses the process of glioma cells by decreasing miR-10b, which as accompanied by Sirt1 silence-induced inactivation of PTEN/PI3K/AKT and MEK/ERK cascades.

The neuroprotective effects of SIRT1 in mice carrying the APP/PS1 double-transgenic mutation and in SH-SY5Y cells over-expressing human APP670/671 may involve elevated levels of α7 nicotinic acetylcholine receptors

The aim was to determine whether the neuroprotective effect of SIRT1 in Alzheimer’s disease (AD), due to inhibition of aggregation of the β-amyloid peptide (Aβ), involves activation of α7 nAChR. In present study, four-month-old APP/PS1 mice were administered resveratrol (RSV) or suramin once daily for two months, following which their spatial learning and memory were assessed using the Morris water maze test. Deposits of Aβ in vivo were detected by near-infrared imaging (NIRI) and confocal laser scanning. SH-SY5Y/APP_swe cells were treated with RSV, suramin, U0126 or methyllycaconitine (MLA). Levels of proteins and mRNA were determined by Western blotting and qRT-PCR, respectively. The results show that activation of SIRT1 improved their spatial learning and memory and reduced the production and aggregation of Aβ in the hippocampus and cerebral cortex; whereas inhibition of SIRT1 had the opposite effects. In addition, activation of SIRT1 increased the levels of both α7 nAChR and αAPP in the brains these animals. Finally, activation of SIRT1 elevated the levels of pERK1/2, while inhibition of ERK1/2 counteracted the increase in α7 nAChR caused by RSV. These findings indicate that neuroprotection by SIRT1 may involve increasing levels of α7 nAChR through activation of the MAPK/ERK1/2 signaling pathway.

Expression and function of FRA1 protein in tumors

AP-1 is a dimeric complex that is composed of JUN, FOS, ATF and MAF protein families. FOS-related antigen 1 (FRA1) which encoded by FOSL1 gene, belongs to the FOS protein family, and mainly forms an AP-1 complex with the protein of the JUN family to exert an effect. Regulation of FRA1 occurs at levels of transcription and post-translational modification, and phosphorylation is the major post-translational modification. FRA1 is mainly regulated by the mitogen-activated protein kinases signaling pathway and is degraded by ubiquitin-independent proteasomes. FRA1 can affect biological functions, such as tumor proliferation, differentiation, invasion and apoptosis. Studies have demonstrated that FRA1 is abnormally expressed in many tumors and plays a relevant role, but the specific condition varies from the target organs. FRA1 is overexpressed in breast cancer, lung cancer, colorectal cancer, prostate cancer, nasopharyngeal cancer, thyroid cancer and other tumors. However, the expression of FRA1 is decreased in cervical cancer, and the expression of FRA1 in ovarian cancer and oral squamous cell carcinoma is still controversial. In this review, we present a detailed description of the regulatory factors and functions of FRA1, also, the expression of FRA1 in various tumors and its function in relative tumor.

SIRT5 downregulation is associated with poor prognosis in glioblastoma

OBJECTIVE

Sirtuins (SIRT) are NAD+-dependent protein deacetylases that are involved in the regulation of cancer-associated pathways. However, the biological role of these deacetylases remains elusive in glioblastoma (GBM). Here, we evaluated the effects of 7 sirtuins regarding their occurrence and prognostic value for GBM.

METHODS

In this research, the effects of SIRT5 on the occurrence and prognosis of GBM were evaluated using integrative bioinformatics analyses.

RESULTS

Based on comprehensive analyses of data obtained from web-based bioinformatics platforms, the data demonstrate that only SIRT5 expression is statistically decreased in GBM tissues. The clinical relevance analysis shows that downregulation of SIRT5 is significantly correlated with a shorter survival time. Moreover, the expression levels of SIRT5 were confirmed to be negatively associated with DNA methylation status. In addition, a protein-protein interaction network was constructed to determine the relationship of genes coexpressed with SIRT5. Functional enrichment analysis revealed that SIRT5 was potentially involved in epithelial-mesenchymal transition and in regulating cell communications.

CONCLUSIONS

Collectively, our results indicate that SIRT5 acts as a potential suppresser during tumorigenesis, and suggest that SIRT5 may be a promising prognostic biomarker of GBM.

Metabolic Plasticity and Epithelial-Mesenchymal Transition

A major transcriptional and phenotypic reprogramming event during development is the establishment of the mesodermal layer from the ectoderm through epithelial-mesenchymal transition (EMT). EMT is employed in subsequent developmental events, and also in many physiological and pathological processes, such as the dissemination of cancer cells through metastasis, as a reversible transition between epithelial and mesenchymal states. The remarkable phenotypic remodeling accompanying these transitions is driven by characteristic transcription factors whose activities and/or activation depend upon signaling cues and co-factors, including intermediary metabolites. In this review, we summarize salient metabolic features that enable or instigate these transitions, as well as adaptations undergone by cells to meet the metabolic requirements of their new states, with an emphasis on the roles played by the metabolic regulation of epigenetic modifications, notably methylation and acetylation.

Prognostic significance of lymphovascular invasion in colorectal cancer and its association with genomic alterations

BACKGROUND

Lymphovascular invasion (LVI) is suggested to be an early and important step in tumor progression toward metastasis, but its prognostic value and genetic mechanisms in colorectal cancer (CRC) have not been well investigated.

AIM

To investigate the prognostic value of LVI in CRC and identify the associated genomic alterations.

METHODS

We performed a retrospective analysis of 1219 CRC patients and evaluated the prognostic value of LVI for overall survival by the Kaplan-Meier method and multivariate Cox regression analysis. We also performed an array-based comparative genomic hybridization analysis of 47 fresh CRC samples to examine the genomic alterations associated with LVI. A decision tree model was applied to identify special DNA copy number alterations (DCNAs) for differentiating between CRCs with and without LVI. Functional enrichment and protein-protein interaction network analyses were conducted to explore the potential molecular mechanisms of LVI.

RESULTS

LVI was detected in 150 (12.3%) of 1219 CRCs, and the presence was positively associated with higher histological grade and advanced tumor stage (both P < 0.001). Compared with the non-LVI group, the LVI group showed a 1.77-fold (95% confidence interval: 1.40-2.25, P < 0.001) increased risk of death and a significantly lower 5-year overall survival rate (P < 0.001). Based on the comparative genomic hybridization data, 184 DCNAs (105 gains and 79 losses) were identified to be significantly related to LVI (P < 0.05), and the majority were located at 22q, 17q, 10q, and 6q. We further constructed a decision tree classifier including seven special DCNAs, which could distinguish CRCs with LVI from those without it at an accuracy of 95.7%. Functional enrichment and protein-protein interaction network analyses revealed that the genomic alterations related to LVI were correlated with inflammation, epithelial-mesenchymal transition, angiogenesis, and matrix remodeling.

CONCLUSION

LVI is an independent predictor for survival in CRC, and its development may correlate with inflammation, epithelial-mesenchymal transition, angiogenesis, and matrix remodeling.

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.

Effects of SIRT1 silencing on viability, invasion and metastasis of human glioma cell lines

Silent information regulator 1 (SIRT1), a member of the sirtuin family, is involved in the development of various types of tumor. Previous studies have revealed that SIRT1 has dual functions, as a promoter and an inhibitor, in certain tumors. However, the role of SIRT1 in invasion and metastasis of glioma cells and its associated signaling pathway remain unclear. The aim of the present study was to determine the effects of SIRT1 on these processes and on the epithelial-mesenchymal transition (EMT) in human glioma and adjacent tissues, and in the human glioma cell lines U87 and U251. SIRT1 expression in tissues was investigated using the reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry. The U87 and U251 cell lines were divided into control and SIRT1-small interfering RNA (siRNA) groups. The Cell Counting Kit-8, cell invasion assays were used to evaluate the effects of SIRT1 silencing on cell viability, invasion and EMT. Results indicated that SIRT1 was highly expressed in glioma tissues compared with in adjacent brain tissues. In addition, SIRT1-siRNA significantly inhibited the viability and invasion of U87 and U251 cells. Furthermore, EMT analysis revealed that the expression levels of the mesenchymal markers fibronectin and vimentin were significantly lower in the SIRT1-siRNA group compared with in the control group. Conversely, expression levels of the epithelial markers epithelial cadherin and β-catenin were significantly higher in the SIRT1-siRNA group compared with in the control group. In conclusion, the results of the present study indicated that SIRT1 was positively associated with viability and invasion of U87 cells, potentially through EMT. These results suggested that SIRT1 may serve a crucial role in the proliferation and development of glioma.

SIRT1 knock-in mice preserve ovarian reserve resembling caloric restriction

Previous studies have proposed that caloric restriction (CR) regulates many cell functions and prolongs the lifespan of an organism. Our previous studies proposed that CR also prevents follicular activation and preserves the ovarian reserve in mice by activating SIRT1. To test if SIRT1 preserves the ovarian reserve and prolongs the ovarian longevity, we generated SIRT1 knock-in mice that can overexpress SIRT1 in oocytes of the mouse. Ovaries of the mice at ages 35 days and 15 months were collected, and the follicular development and follicular reserve were examined. The vaginal opening and onset of estrus of transgenic female mice (both the homozygous and heterozygous for SIRT1 overexpression) were later than that of wild-type mice. Both the homozygous and heterozygous SIRT1-overexpressing mice had a larger and stronger reproductive capacity than wild-type mice. Moreover, 35-day-old and 15-month-old homozygous and heterozygous SIRT1-overexpressing mice also had a higher mean number and percentage of healthy follicles, fewer atretic follicles than wild-type mice, and the mean number and percentage of primordial follicles in both the homozygous and heterozygous SIRT1-overexpressing mice were higher than wild-type mice at the same age. However, the phenotypes of heterozygous and homozygous transgenic mice came no difference. Immunohistochemistry showed increased expression of SIRT1 and FOXO3a, and decreased expression of mTOR in both the homozygous and heterozygous SIRT1-overexpressing mice compared with wild-type mice. Thus, oocyte-specific SIRT1-overexpressing mice continuously activate FOXO3a and suppress mTOR and have a larger reproductive capacity, larger follicle reserve and longer ovarian lifespan.