Negative regulation of Sirtuin 1 by AMP-activated protein kinase promotes metformin-induced senescence in hepatocellular carcinoma xenografts

Recent advances in caspase-3, breast cancer, and traditional Chinese medicine: a review

Caspases (cysteinyl aspartate-specific proteinases) are a group of structurally similar proteases in the cytoplasm that can be involved in cell differentiation, programmed death, proliferation, and inflammatory generation. Experts have found that caspase-3 can serve as a terminal splicing enzyme in apoptosis and participate in the mechanism by which cytotoxic drugs kill cancer cells. Breast cancer (BC) has become the most common cancer among women worldwide, posing a severe threat to their lives. Finding new therapeutic targets for BC is the primary task of contemporary physicians. Numerous studies have revealed the close association between caspase-3 expression and BC. Caspase-3 is essential in BC's occurrence, invasion, and metastasis. In addition, Caspase-3 exerts anticancer effects by regulating cell death mechanisms. Traditional Chinese medicine acting through caspase-3 expression is increasingly used in clinical treatment. This review summarizes the biological mechanism of caspase-3 and research progress on BC. It introduces a variety of traditional Chinese medicine related to caspase-3 to provide new ideas for the clinical treatment of BC.

Metformin: A Dual-Role Player in Cancer Treatment and Prevention

Cancer continues to pose a significant global health challenge, as evidenced by the increasing incidence rates and high mortality rates, despite the advancements made in chemotherapy. The emergence of chemoresistance further complicates the effectiveness of treatment. However, there is growing interest in the potential of metformin, a commonly prescribed drug for type 2 diabetes mellitus (T2DM), as an adjuvant chemotherapy agent in cancer treatment. Although the precise mechanism of action of metformin in cancer therapy is not fully understood, it has been found to have pleiotropic effects, including the modulation of metabolic pathways, reduction in inflammation, and the regulation of cellular proliferation. This comprehensive review examines the anticancer properties of metformin, drawing insights from various studies conducted in vitro and in vivo, as well as from clinical trials and observational research. This review discusses the mechanisms of action involving both insulin-dependent and independent pathways, shedding light on the potential of metformin as a therapeutic agent for different types of cancer. Despite promising findings, there are challenges that need to be addressed, such as conflicting outcomes in clinical trials, considerations regarding dosing, and the development of resistance. These challenges highlight the importance of further research to fully harness the therapeutic potential of metformin in cancer treatment. The aims of this review are to provide a contemporary understanding of the role of metformin in cancer therapy and identify areas for future exploration in the pursuit of effective anticancer strategies.

Metformin and cancer hallmarks: shedding new lights on therapeutic repurposing

Metformin is a well-known anti-diabetic drug that has been repurposed for several emerging applications, including as an anti-cancer agent. It boasts the distinct advantages of an excellent safety and tolerability profile and high cost-effectiveness at less than one US dollar per daily dose. Epidemiological evidence reveals that metformin reduces the risk of cancer and decreases cancer-related mortality in patients with diabetes; however, the exact mechanisms are not well understood. Energy metabolism may be central to the mechanism of action. Based on altering whole-body energy metabolism or cellular state, metformin's modes of action can be divided into two broad, non-mutually exclusive categories: "direct effects", which induce a direct effect on cancer cells, independent of blood glucose and insulin levels, and "indirect effects" that arise from systemic metabolic changes depending on blood glucose and insulin levels. In this review, we summarize an updated account of the current knowledge on metformin antitumor action, elaborate on the underlying mechanisms in terms of the hallmarks of cancer, and propose potential applications for repurposing metformin for cancer therapeutics.

Role of metformin in inflammation

BACKGROUND

Metformin has good anti-hyperglycemic effectiveness, but does not induce hypoglycemia，is very safe, and has become the preferred drug for the treatment of type 2 diabetes. Recently, the other effects of metformin, such as being anti-inflammatory and delaying aging, have also attracted increased attention.

METHODS AND RESULTS

The relevant literatures on pubmed and other websites for reading, classification and sorting, and did not involve any animal experiments.

CONCLUSION

Metformin has anti-inflammatory effects through multiple routes, which provides potential therapeutic targets for certain inflammatory diseases, such as neuroinflammation and rheumatoid arthritis. In addition, inflammation is a key component of tumor occurrence and development ; thus, targeted inflammatory intervention is a significant benefit for both cancer prevention and treatment. Therefore, metformin may have further potential for inflammation-related disease prevention and treatmen. However, the inflammatory mechanism is complex; various molecules are connected and influence each other. For example, metformin significantly inhibits p65 nuclear translocation, but pretreatment with compound C, an AMPK inhibitor, abolishes this effect, and silencing of HMGB1 inhibits NF-κB activation . SIRT1 deacetylates FoxO, increasing its transcriptional activity . mTOR in dendritic cells regulates FoxO1 via AKT. The interactions among various molecules should be further explored to clarify their specific mechanisms and provide more direction for the treatment of inflammatory diseases, as well as cancer.

Applications and mechanisms of the cyclin-dependent kinase 4/6 inhibitor, PD-0332991, in solid tumors

Abnormal CDK4/6-Rb-E2F signal transduction is a common finding in tumors and is a driving factor for the excessive proliferation of various tumor cells. PD-0332991, a highly specific, small molecule inhibitor for CDK4 and 6, has been shown to inhibit tumor growth by abrogating the phosphorylating capacity of CDK4/6 and suppressing Rb phosphorylation. It has been promoted for the treatment of breast cancer and potentially for other tumor types such as liver cancers, lung cancers and sarcomas. Due to the risk of monotherapy resistance, PD-0332991 is commonly used in combination with other drugs. Such combination treatments have proved able to inhibit tumor proliferation more effectively, induce stronger senescence and apoptosis, and enhance the efficiency of immunotherapy. Therefore, tumor cells with senescence induced by PD-0332991 are now used as ideal screening tools of cytolytic drugs with more efficient and thorough anti-tumor properties. With more extensive understandings about the branching points between senescence and apoptosis, it is possible to refine the dosage of PD-0332991. Better characterization of resistant cells, of inhibitors and of adverse effects such as leukopenia are needed to overcome obstacles in the use of PD-0332991. In this review of PD-0332991 research, we hope to provide guidance of transitions from laboratory findings to clinical applications of PD-0332991 and to facilitate PD-0332991-based multi-inhibitor combination therapies for various tumors.

Anticancer effects of metformin in experimental animal models of different types of cancer: a systematic review and meta-analysis

To systematically evaluate the effects of metformin on tumors in experimental animal models of different types of cancer. Pubmed, Embase, Cochrane, and Web of Science databases were searched for studies on metformin used in various experimental animal tumor models from 2008 to 2022. Meta-analysis was performed using STATA 16.0 software after screening literature extraction data and methodological quality evaluation by inclusion and exclusion criteria. A total of 24 studies with 1108 model animals were included. Meta-analysis results showed that this study used meta-analysis for quantitative synthesis of study results and found that tumor model animals of different species showed different degrees of reduction in tumor volume, weight, and number after metformin intervention.

Metabolism-Associated Epigenetic and Immunoepigenetic Reprogramming in Liver Cancer

Metabolic reprogramming and epigenetic changes have been characterized as hallmarks of liver cancer. Independently of etiology, oncogenic pathways as well as the availability of different energetic substrates critically influence cellular metabolism, and the resulting perturbations often cause aberrant epigenetic alterations, not only in cancer cells but also in the hepatic tumor microenvironment. Metabolic intermediates serve as crucial substrates for various epigenetic modulations, from post-translational modification of histones to DNA methylation. In turn, epigenetic changes can alter the expression of metabolic genes supporting on the one hand, the increased energetic demand of cancer cells and, on the other hand, influence the activity of tumor-associated immune cell populations. In this review, we will illustrate the most recent findings about metabolic reprogramming in liver cancer. We will focus on the metabolic changes characterizing the tumor microenvironment and on how these alterations impact on epigenetic mechanisms involved in the malignant progression. Furthermore, we will report our current knowledge about the influence of cancer-specific metabolites on epigenetic reprogramming of immune cells and we will highlight how this favors a tumor-permissive immune environment. Finally, we will review the current strategies to target metabolic and epigenetic pathways and their therapeutic potential in liver cancer, alone or in combinatorial approaches.

High lymphocyte‑to‑monocyte ratio is associated with low α‑fetoprotein expression in patients with hepatitis B virus‑associated hepatocellular carcinoma

The association of the peripheral lymphocyte‑to‑monocyte ratio (LMR) with α‑fetoprotein (AFP) status in patients with AFP‑positive and AFP‑negative hepatocellular carcinoma (HCC) has not been investigated in detail. The aim of the present study was to examine the association between the LMR and AFP status in these patients. The samples were obtained from patients with a hepatitis B virus (HBV) infection, who were negative for non‑HBV hepatitis viruses and who did not suffer from autoimmune hepatitis. These patients were retrospectively reviewed and the differences of test indicators in the AFP‑negative and AFP‑positive groups were assessed. Flow cytometry was used to detect the expression levels of CD4, CD8 and programmed cell death protein 1 (PD‑1), and ELISAs were used to analyze the expression levels of interleukin (IL)‑10 and transforming growth factor (TGF)‑β1. In addition, luciferase reporter assays were used to assess binding of the IL‑10 promoter to the glucocorticoid receptor (GR) gene. Receiver operating characteristic curve and Spearman correlation analyses demonstrated that the AFP‑negative HCC group exhibited a higher LMR, lower D‑dimer and lower fibrin degradation products compared with the AFP‑positive HCC group. The cut‑off value of the LMR was 2.01 for AFP detection, with a sensitivity of 68.6% and a specificity of 75%. The high LMR noted in the AFP‑negative HCC group was accompanied by a lower proportion of CD4+ T lymphocytes and CD8‑PD‑1 expression compared with the corresponding levels of these parameters in the AFP‑positive HCC group. Furthermore, the high levels of IL‑10 and low levels of TGF‑β1 were expressed in the AFP‑positive HCC group. The data indicated that the IL‑10‑592 promoter exhibited a potent induction of luciferase activity in 293T cells cotransfected with a GR‑overexpressing vector compared with the control cells. However, the relative luciferase activity was not altered following a mutation or polymorphism in the IL‑10 gene. These results suggested that a high LMR was indicative of low AFP expression in HBV‑associated HCC patients.

Loss of SIRT4 promotes the self-renewal of Breast Cancer Stem Cells

Rationale: It has been proposed that cancer stem/progenitor cells (or tumor-initiating cells, TICs) account for breast cancer initiation and progression. Sirtuins are nicotinamide adenine dinucleotide (NAD+)-dependent class-III histone deacetylases and mediate various basic biological processes, including metabolic homeostasis. However, interplay and cross-regulation among the sirtuin family are not fully understood. As one of the least studied sirtuin family members, the mitochondrial sirtuin SIRT4 is a tumor suppressor gene in various cancers. However, its role in cancer stemness, as well as initiation and progression of breast cancer, remains unknown. Methods: The expression of SIRT4 in breast cancer was analyzed using the TCGA breast cancer database and 3 GSEA data. Normal breast epithelial cells MCF10A and breast cancer cell lines MCF-7, MDA-MB-231, BT549, MDA-MB-468 were used to establish SIRT4 gene knockdown and corresponding overexpression cells. Identified MTT cytotoxicity assays, cell invasion and motility assay, sorting of SP, confocal immunofluorescence microscopy, mouse mammary stem cell analysis, glutamine and glucose production, clonogenic and sphere-formation assay, mass spectrometric metabolomics analysis and ChIP-seq to further explore SIRT4 biological role in breast cancer. Results: We elucidated a novel role for SIRT4 in the negative regulation of mammary gland development and stemness, which is related to the mammary tumorigenesis. We also uncovered an inverse correlation between SIRT4 and SIRT1. Most importantly, SIRT4 negatively regulates SIRT1 expression via repressing glutamine metabolism. Besides, we identified H4K16ac and BRCA1 as new prime targets of SIRT4 in breast cancer. Conclusions: These results demonstrate that SIRT4 exerts its tumor-suppressive activity via modulating SIRT1 expression in breast cancer and provide a novel cross-talk between mitochondrial and nuclear sirtuins.

MiRNA-12129 Suppresses Cell Proliferation and Block Cell Cycle Progression by Targeting SIRT1 in GASTRIC Cancer

Gastric cancer is the most commonly occurring cancer with a rapidly increasing incidence rate worldwide. The underlying molecular mechanisms of gastric cancer require further investigation. MicroRNAs exhibit tissue sensitivity as tumor biomarkers that play a role by promoting tumor growth as oncogenes or tumor suppressor genes. We evaluated the effects of microRNA-12129 on gastric cancer and identified the underlying mechanisms of microRNA-12129. Quantitative real-time polymerase chain reaction was conducted to determine the expression levels of microRNA-12129 and sirtuin 1 in vivo and in vitro, and Western blot analysis was performed to detect sirtuin 1 at the protein level in gastric cancer cell lines. Cell proliferation and cell cycle progression were detected by Cell Counting Kit-8 assay and flow cytometry analysis, respectively. The potential targets of microRNA-12129 were predicted by bioinformatics analysis. The targets of microRNA-12129 were confirmed by luciferase reporter assay and rescue assay. We found that microRNA-12129 was downregulated in gastric cancer tissues and gastric cancer cell lines and was significantly associated with the prognosis of patients with gastric cancer. In addition, microRNA-12129 overexpression suppressed tumor cell proliferation and blocked cell cycle progression. Bioinformatics analysis and luciferase reporter assay suggested that sirtuin 1 was a target of microRNA-12129, and sirtuin 1 expression was negatively related to microRNA-12129. Restoration of sirtuin 1 partly reduced the inhibition of cell proliferation and cell cycle progression induced by microRNA-144. Our results collectively suggested that microRNA-12129 suppressed cell proliferation and cell cycle progression in gastric cancer by targeting sirtuin 1. These findings indicated that manipulation of microRNA-12129 expression could help develop a novel therapeutic strategy for gastric cancer.

Large-scale analyses identify a cluster of novel long noncoding RNAs as potential competitive endogenous RNAs in progression of hepatocellular carcinoma

The abnormal expression of noncoding RNAs has attracted increasing interest in the field of hepatocellular carcinoma progression. However, the underlying molecular mechanisms mediated by noncoding RNAs in these processes are unclear. Here, we obtained the expression profiles of long noncoding RNAs, microRNAs, and mRNAs from the Gene Expression Omnibus database and identified hepatocarcinogenesis-specific differentially expressed transcripts. Next, we identified significant Gene Ontology and pathway terms that the differentially expressed transcripts involved in. Using functional analysis and target prediction, we constructed a hepatocellular carcinoma-associated deregulated competitive endogenous RNA network to reveal the potential mechanisms underlying tumor progression. By analyzing The Cancer Genome Atlas dataset, six key long noncoding RNAs showed significant association with overall survival as well as strong correlation with some microRNAs and mRNAs in the competitive endogenous RNA network. We further validated the above results and determined their diagnostic and prognostic value in clinical samples. Importantly, by large-scale analyses, we identified a cluster of long noncoding RNAs, GBAP1, MCM3AP-AS1, SLC16A1-AS1, C3P1, DIO3OS, and HNF4A-AS1 as candidate biomarkers for the diagnosis and prognosis of hepatocellular carcinoma, which will improve our understanding of competitive endogenous RNA-mediated regulatory mechanisms underlying hepatocellular carcinoma development and will provide novel therapeutic targets in the future.

SIRT1 in the Development and Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Current treatment options for inoperable HCCs have decreased therapeutic efficacy and are associated with systemic toxicity and chemoresistance. Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide–dependent enzyme that is frequently overexpressed in HCC, where it promotes tumorigenicity, metastasis, and chemoresistance. SIRT1 also maintains the tumorigenic and self-renewal proprieties of liver cancer stem cells. Multiple tumor-suppressive microRNAs (miRNAs) are downregulated in HCC and, as a consequence, permit SIRT1-induced tumorigenicity. However, either directly targeting SIRT1, combining conventional chemotherapy with SIRT1 inhibitors, or upregulating tumor-suppressive miRNAs may improve therapeutic efficacy and patient outcomes. Here, we present the interaction between SIRT1, miRNAs, and liver cancer stem cells and discuss the consequences of their interplay for the development and treatment of HCC.

Negative regulation of AMPKα1 by PIM2 promotes aerobic glycolysis and tumorigenesis in endometrial cancer

Endometrial cancer (EC) is one of the most common gynecologic malignancies. However, the molecular mechanisms underlying the development and progression of EC remain unclear. Here, we demonstrated that the protein proviral insertion in murine lymphomas 2 (PIM2) was necessary for maintaining EC tumorigenesis in vivo and in vitro, and could inhibit AMPKα1 kinase activity in EC cells. Specifically, we found that PIM2 bound to AMPKα1, and directly phosphorylated it on Thr467. Phosphorylation of AMPKα1 by PIM2 led to decreasing AMPKα1 kinase activity, which in turn promoted aerobic glycolysis and tumor growth. In addition, PIM2 expression positively correlated with AMPKα1 Thr467 phosphorylation in EC tissues. Further, treatment with a combination of the PIM2 inhibitor SMI-4a and the AMPKα1 activator AICAR could effectively inhibit tumor growth. Thus, our findings provide insight into the role of PIM2 and AMPKα1 in EC and suggest that combination targeting of these proteins may represent a new strategy for EC treatment.

Metformin induces human esophageal carcinoma cell pyroptosis by targeting the miR-497/PELP1 axis

Evasion of apoptosis is a major contributing factor to the development of chemo- and radiotherapy resistance. Therefore, activation of non-apoptotic programmed cell death (PCD) could be an effective alternative against apoptosis-resistant cancers. In this study, we demonstrated in vitro and in vivo that metformin can induce pyroptosis, a non-apoptotic PCD, in esophageal squamous cell carcinoma (ESCC), a commonly known chemo-refractory cancer, especially at its advanced stages. Proline-, glutamic acid- and leucine-rich protein-1 (PELP1) is a scaffolding oncogene and upregulated PELP1 in advanced stages of ESCC is highly associated with cancer progression and patient outcomes. Intriguingly, metformin treatment leads to gasdermin D (GSDMD)-mediated pyroptosis, which is abrogated by forced expression of PELP1. Mechanistically, metformin induces pyroptosis of ESCC by targeting miR-497/PELP1 axis. Our findings suggest that metformin and any other pyroptosis-inducing reagents could serve as alternative treatments for chemo- and radiotherapy refractory ESCC or other cancers sharing the same pyroptosis mechanisms.

The Role of AMP-Activated Protein Kinase as a Potential Target of Treatment of Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide with a very high recurrence rate and very dismal prognosis. Diagnosis and treatment in HCC remain difficult, and the identification of new therapeutic targets is necessary for a better outcome of HCC treatment. AMP-Activated Protein Kinase (AMPK) is an essential intracellular energy sensor that plays multiple roles in cellular physiology and the pathological development of chronic diseases. Recent studies have highlighted the important regulation of AMPK in HCC. This review aims to comprehensively and critically summarize the role of AMPK in HCC. Methods: Original studies were retrieved from NCBI database with keywords including AMPK and HCC, which were analyzed with extensive reading. Results: Dysregulation of the kinase activity and expression of AMPK was observed in HCC, which was correlated with survival of the patients. Loss of AMPK in HCC cells may proceed cell cycle progression, proliferation, survival, migration, and invasion through different oncogenic molecules and pathways. Conclusions: We identified several AMPK activators which may possess potential anti-HCC function, and discussed the clinical perspective on the use of AMPK activators for HCC therapy.

Treatment with metformin is associated with a prolonged survival in patients with hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most lethal cancers. Nutrition- and life style-associated risk factors are increasingly prevalent. Metformin, the mainstay of type 2 diabetes mellitus (T2DM)-treatment, reduces the risk of hepatocarcinogenesis. However, its influence on the prognosis of patients with HCC has not been investigated on a large scale, yet.

METHODS

Five thousand and ninety-three patients treated for HCC between 2000 and 2016 at three referral centres were included in this retrospective multicentre study. The aim of this study was to assess whether treatment with metformin for T2DM is associated with a prolonged overall survival (OS) in patients diagnosed with HCC.

RESULTS

Among 5093 patients with HCC, 1917 patients (37.6%) were diagnosed with T2DM, of which 338 (17.6%) received treatment with metformin. Compared to diabetic patients not treated with metformin, patients on metformin had a significantly better hepatic function (Child-Pugh-Score A: 69.2% vs 47.4%, P < 0.001) and underwent significantly more often tumour resection (22.1% vs 16.5%, P = 0.024). Patients on metformin had a significantly longer median OS (mOS) compared to diabetic patients not treated with metformin (22 vs 15 months, P = 0.019). The prolongation of survival was most significant in patients treated with surgery. Using a propensity score match (PSM), patients were adjusted for hepatic function and initial therapy. In the matched cohorts, mOS remained significantly longer in metformin-treated patients (22 vs 16 months, P = 0.021). Co-treatment of metformin and sorafenib was associated with a survival disadvantage.

CONCLUSION

Treatment with metformin was associated with an improved survival in patients with T2DM and HCC. This effect was most pronounced in patients at potentially curative tumour stages.

SIRT1 in Secretory Organ Cancer

Mammalian silent information regulator 1 (SIRT1) is reported to play a role in cancers of the secretory organs, including thyroid, pancreatic endocrine, and ovarian tumors [1, 2, 3, 4]. A recent meta-analysis conducted on 37 selected studies of human cancers analyzed the correlations of overall survival (OS), disease-free survival (DFS) and relapse-free survival (RFS) with SIRT1 expression [5]. This study reported that SIRT1 overexpression was associated with a worse OS in liver and lung cancers, while it was not correlated with OS in breast cancer, colorectal cancer, or gastric carcinoma. Collectively, the meta-analysis revealed that an unfavorable OS was associated with SIRT1 expression for solid malignancies. Given the growing importance of this class of lysine/histone deacetylases in human endocrine malignancies, a rational and focused literature assessment is desirable in light of future clinical translations.