Expression of sirtuin 1 and 2 is associated with poor prognosis in non-small cell lung cancer patients

Emerging role of sirtuins in non‑small cell lung cancer (Review)

Non‑small cell lung cancer (NSCLC) is a highly prevalent lung malignancy characterized by insidious onset, rapid progression and advanced stage at the time of diagnosis, making radical surgery impossible. Sirtuin (SIRT) is a histone deacetylase that relies on NAD+ for its function, regulating the aging process through modifications in protein activity and stability. It is intricately linked to various processes, including glycolipid metabolism, inflammation, lifespan regulation, tumor formation and stress response. An increasing number of studies indicate that SIRTs significantly contribute to the progression of NSCLC by regulating pathophysiological processes such as energy metabolism, autophagy and apoptosis in tumor cells through the deacetylation of histones or non‑histone proteins. The present review elaborates on the roles of different SIRTs and their mechanisms in NSCLC, while also summarizing novel therapeutic agents based on SIRTs. It aims to present new ideas and a theoretical basis for NSCLC treatment.

Spinal sirtuin 2 attenuates bone cancer pain by deacetylating FoxO3a

Bone cancer pain (BCP) is refractory to currently used analgesics. Recently, sirtuin 2 (SIRT2) was reported to play a vital role in neuropathic pain but its role in BCP remains unknown. It was hypothesized that spinal SIRT2 attenuates BCP by deacetylating FoxO3a and suppressing oxidative stress. The mouse model of BCP established by injecting tumor cells into the intramedullary space of the femur demonstrated that spinal SIRT2 and FoxO3a were downregulated in BCP development. Intrathecal administration of LV-SIRT2 reduced pain hypersensitivity (mechanical and thermal nociception) in BCP mice. Spinal SIRT2 overexpression upregulated FoxO3a and antioxidant genes (SOD2 and catalase) and inhibited FoxO3a acetylation, phosphorylation, and ubiquitination. Moreover, intrathecal administration of SIRT2 shRNA induced pain hypersensitivity in normal mice. Spinal SIRT2 knockdown downregulated FoxO3a and antioxidant genes and increased FoxO3a acetylation, phosphorylation, and ubiquitination. In summary, spinal SIRT2 increases FoxO3a expression in BCP mice and inhibits oxidative stress by deacetylating FoxO3a and further reducing FoxO3a phosphorylation, ubiquitination, and degradation, leading to BCP relief.

SIRT1 ISGylation accelerates tumor progression by unleashing SIRT1 from the inactive state to promote its deacetylase activity

ISG15 is an interferon-stimulated ubiquitin-like protein (UBL) with multifaceted roles as a posttranslational modifier in ISG15 conjugation (ISGylation). However, the mechanistic consequences of ISGylation in cancer have not been fully elucidated, largely due to a lack of knowledge on the ISG15 target repertoire. Here, we identified SIRT1, a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, as a new target for ISGylation. SIRT1 ISGylation impairs the association of SIRT1 with its negative regulator, deleted in breast cancer 1 (DBC1), which unleashes SIRT1 from its inactive state and leads to an increase in its deacetylase activity. Importantly, SIRT1 ISGylation promoted lung cancer progression and limited lung cancer cell sensitivity to DNA damage-based therapeutics in vivo and in vitro models. The levels of ISG15 mRNA and protein were significantly higher in lung cancer tissues than in adjacent normal tissues. Accordingly, elevated expression of SIRT1 and ISG15 was associated with poor prognosis in lung cancer patients, a finding that could be translated for lung cancer patient stratification and disease outcome evaluation. Taken together, our findings provide a mechanistic understanding of the regulatory effect of SIRT1 ISGylation on tumor progression and therapeutic efficacy in lung cancer.

Rhabdomyosarcoma: Current Therapy, Challenges, and Future Approaches to Treatment Strategies

Rhabdomyosarcoma is a rare cancer arising in skeletal muscle that typically impacts children and young adults. It is a worldwide challenge in child health as treatment outcomes for metastatic and recurrent disease still pose a major concern for both basic and clinical scientists. The treatment strategies for rhabdomyosarcoma include multi-agent chemotherapies after surgical resection with or without ionization radiotherapy. In this comprehensive review, we first provide a detailed clinical understanding of rhabdomyosarcoma including its classification and subtypes, diagnosis, and treatment strategies. Later, we focus on chemotherapy strategies for this childhood sarcoma and discuss the impact of three mechanisms that are involved in the chemotherapy response including apoptosis, macro-autophagy, and the unfolded protein response. Finally, we discuss in vivo mouse and zebrafish models and in vitro three-dimensional bioengineering models of rhabdomyosarcoma to screen future therapeutic approaches and promote muscle regeneration.

Oncogenic KRAS mutation confers chemoresistance by upregulating SIRT1 in non-small cell lung cancer

Kirsten rat sarcoma viral oncogene homologue (KRAS) is a frequent oncogenic driver of solid tumors, including non-small cell lung cancer (NSCLC). The treatment and outcomes of KRAS-mutant cancers have not been dramatically revolutionized by direct KRAS-targeted therapies because of the lack of deep binding pockets for specific small molecule inhibitors. Here, we demonstrated that the mRNA and protein levels of the class III histone deacetylase SIRT1 were upregulated by the KRASMut-Raf-MEK-c-Myc axis in KRASMut lung cancer cells and in lung tumors of a mouse model with spontaneous KrasG12D expression. KRASMut-induced SIRT1 bound to KRASMut and stably deacetylated KRASMut at lysine 104, which increased KRASMut activity. SIRT1 knockdown (K/D) or the SIRT1H363Y mutation increased KRASMut acetylation, which decreased KRASMut activity and sensitized tumors to the anticancer effects of cisplatin and erlotinib. Furthermore, in KrasG12D/+;Sirt1co/co mice, treatment with cisplatin and erlotinib robustly reduced the tumor burden and increased survival rates compared with those in spontaneous LSL-KrasG12D/+;Sirt1+/+ mice and mice in each single-drug treatment group. Then, we identified p300 as a KRASMut acetyltransferase that reinforced KRASMut lysine 104 acetylation and robustly decreased KRASMut activity. KRASMut lysine 104 acetylation by p300 and deacetylation by SIRT1 were confirmed by LC‒MS/MS. Consistent with this finding, the SIRT1 inhibitor EX527 suppressed KRASMut activity, which synergistically abolished cell proliferation and colony formation, as well as the tumor burden in KRASMut mice, when combined with cisplatin or erlotinib. Our data reveal a novel pathway critical for the regulation of KRASMut lung cancer progression and provide important evidence for the potential application of SIRT1 inhibitors and p300 activators for the combination treatment of KRASMut lung cancer patients.

Sirtuin 1 inhibition: a promising avenue to suppress cancer progression through small inhibitors design

SIRT1 is a protein associated with vital cell functions such as gene regulation, metabolism, ageing, and cellular energy restoration. Its association with the tumor suppressor protein p53 is essential for controlling the growth of cells, apoptosis, and response to DNA damage. By raising p53 acetylation, encouraging apoptosis, and reducing cell proliferation, inhibiting SIRT1's catalytic domain, which interacts with p53, shows potential as a cancer treatment. The aim of the study is to find compounds that could inhibit SIRT1 and thus lower the proliferation of cancer cells. Employing molecular docking techniques, a virtual screening of ∼900 compounds (isolated from medicinal plants and derivatives) gave us 13 active compounds with good binding affinity. Additional evaluation of pharmacokinetic and pharmacodynamic properties led to the selection of eight compounds with desirable properties. Docking analysis confirmed stable interactions between the final eight compounds (C1-C8) and the SIRT1 catalytic domain. Molecular dynamics simulations show overall stability and moderate changes in protein structure upon compound binding. The compactness of the protein indicated the protein's tight packing upon the inhibitors binding. Binding free energy calculations revealed that compounds C2 (-49.96 ± 0.073 kcal/mol and C1 (-44.79 ± 0.077 kcal/mol) exhibited the highest energy, indicating strong binding affinity to the SIRT1 catalytic domain. These compounds, along with C8, C5, C6, C3, C4 and C7, showed promising potential as SIRT1 inhibitors. Based on their ability to reduce SIRT1 activity and increase apoptosis, the eight chemicals discovered in this work may be useful in treating cancer.Communicated by Ramaswamy H. Sarma.

Evaluating the iron chelator function of sirtinol in non-small cell lung cancer

A distinctive feature of cancer is the upregulation of sirtuin proteins. Sirtuins are class III NAD+-dependent deacetylases involved in cellular processes such as proliferation and protection against oxidative stress. SIRTs 1 and 2 are also overexpressed in several types of cancers including non-small cell lung cancer (NSCLC). Sirtinol, a sirtuin (SIRT) 1 and 2 specific inhibitor, is a recent anti-cancer agent that is cytotoxic against several types of cancers including NSCLC. Thus, sirtuins 1 and 2 represent valuable targets for cancer therapy. Recent studies show that sirtinol functions as a tridentate iron chelator by binding Fe3+ with 3:1 stoichiometry. However, the biological consequences of this function remain unexplored. Consistent with preliminary literature, we show that sirtinol can deplete intracellular labile iron pools in both A549 and H1299 non-small cell lung cancer cells acutely. Interestingly, a temporal adaptive response occurs in A549 cells as sirtinol enhances transferrin receptor stability and represses ferritin heavy chain translation through impaired aconitase activity and apparent IRP1 activation. This effect was not observed in H1299 cells. Holo-transferrin supplementation significantly enhanced colony formation in A549 cells while increasing sirtinol toxicity. This effect was not observed in H1299 cells. The results highlight the fundamental genetic differences that may exist between H1299 and A549 cells and offer a novel mechanism of how sirtinol kills NSCLC cells.

Unraveling the Post-Translational Modifications and therapeutical approach in NSCLC pathogenesis

Non-Small Cell Lung Cancer (NSCLC) is the most prevalent kind of lung cancer with around 85% of total lung cancer cases. Despite vast therapies being available, the survival rate is low (5 year survival rate is 15%) making it essential to comprehend the mechanism for NSCLC cell survival and progression. The plethora of evidences suggests that the Post Translational Modification (PTM) such as phosphorylation, methylation, acetylation, glycosylation, ubiquitination and SUMOylation are involved in various types of cancer progression and metastasis including NSCLC. Indeed, an in-depth understanding of PTM associated with NSCLC biology will provide novel therapeutic targets and insight into the current sophisticated therapeutic paradigm. Herein, we reviewed the key PTMs, epigenetic modulation, PTMs crosstalk along with proteogenomics to analyze PTMs in NSCLC and also, highlighted how epi‑miRNA, miRNA and PTM inhibitors are key modulators and serve as promising therapeutics.

Promotion of Lung Cancer Metastasis by SIRT2-Mediated Extracellular Protein Deacetylation

Acetylation of extracellular proteins has been observed in many independent studies where particular attention has been given to the dynamic change of the microenvironmental protein post-translational modifications. While extracellular proteins can be acetylated within the cells prior to their micro-environmental distribution, their deacetylation in a tumor microenvironment remains elusive. Here it is described that multiple acetyl-vWA domain-carrying proteins including integrin β3 (ITGB3) and collagen 6A (COL6A) are deacetylated by Sirtuin family member SIRT2 in extracellular space. SIRT2 is secreted by macrophages following toll-like receptor (TLR) family member TLR4 or TLR2 activation. TLR-activated SIRT2 undergoes autophagosome translocation. TNF receptor associated factor 6 (TRAF6)-mediated autophagy flux in response to TLR2/4 activation can then pump SIRT2 into the microenvironment to function as extracellular SIRT2 (eSIRT2). In the extracellular space, eSIRT2 deacetylates ITGB3 on aK416 involved in cell attachment and migration, leading to a promotion of cancer cell metastasis. In lung cancer patients, significantly increased serum eSIRT2 level correlates with dramatically decreased ITGB3-K416 acetylation in cancer cells. Thus, the extracellular space is a subcellular organelle-like arena where eSIRT2 promotes cancer cell metastasis via catalyzing extracellular protein deacetylation.

Shedding light on structure, function and regulation of human sirtuins: a comprehensive review

Sirtuins play an important role in signalling pathways associated with various metabolic regulations. They possess mono-ADP-ribosyltransferase or deacylase activity like demalonylase, deacetylase, depalmitoylase, demyristoylase and desuccinylase activity. Sirtuins are histone deacetylases which depends upon nicotinamide adenine dinucleotide (NAD) that deacetylate lysine residues. There are a total of seven human sirtuins that have been identified namely, SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7. The subcellular location of mammalian sirtuins, SIRT1, SIRT6, and SIRT7 are in the nucleus; SIRT3, SIRT4, and SIRT5 are in mitochondria, and SIRT2 is in cytoplasm. Structurally sirtuins contains a N-terminal, a C-terminal and a Zn+ binding domain. The sirtuin family has been found to be crucial for maintaining lipid and glucose homeostasis, and also for regulating insulin secretion and sensitivity, DNA repair pathways, neurogenesis, inflammation, and ageing. Based on the literature, sirtuins are overexpressed and play an important role in tumorigenicity in various types of cancer such as non-small cell lung cancer, colorectal cancer, etc. In this review, we have discussed about the different types of human sirtuins along with their structural and functional features. We have also discussed about the various natural and synthetic regulators of sirtuin activities like resveratrol. Our overall study shows that the correct regulation of sirtuins can be a good target for preventing and treating various diseases for improving the human lifespan. To investigate the true therapeutic potential of sirtuin proteins and their efficacy in a variety of pathological diseases, a better knowledge of the link between the structure and function of sirtuin proteins would be necessary.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Role of Sirtuins in the Pathobiology of Onco-Hematological Diseases: A PROSPERO-Registered Study and In Silico Analysis

Simple Summary

The aging of the hematological system can cause physiological disorders such as anemia, reduced immunity, and the increased incidence of blood cancer. Patients diagnosed with hematologic malignancies comprise nearly 10% of all cancer deaths identified in international epidemiologic studies. Therefore, it is considered a public health problem worldwide. Scientific evidence demonstrates the important involvement of sirtuins (SIRTs) in the pathogenesis of several types of solid tumors. However, the role of SIRTs in the pathobiology of malignant hematological diseases has not yet been systematically reviewed. In this systematic review, we highlight the role of different SIRTs in the pathogenesis of acute and chronic leukemias, lymphoma and myeloma. Also, we performed a bioinformatic analysis to identify whether the expression of SIRTs is altered in onco-hematological diseases, such as lymphomas and leukemias. The advent of new applicability of SIRTs in the process of aging and hematological carcinogenesis may allow the development of new diagnostic and therapeutic approaches for these diseases.

Abstract

The sirtuins (SIRT) gene family (SIRT1 to SIRT7) contains the targets implicated in cellular and organismal aging. The role of SIRTs expression in the pathogenesis and overall survival of patients diagnosed with solid tumors has been widely discussed. However, studies that seek to explain the role of these pathways in the hematopoietic aging process and the consequences of their instability in the pathogenesis of different onco-hematological diseases are still scarce. Therefore, we performed a systematic review (registered in PROSPERO database #CRD42022310079) and in silico analysis (based on GEPIA database) to discuss the role of SIRTs in the advancement of pathogenesis and/or prognosis for different hematological cancer types. In summary, given recent available scientific evidence and in silico gene expression analysis that supports the role of SIRTs in pathobiology of hematological malignances, such as leukemias, lymphomas and myeloma, it is clear the need for further high-quality research and clinical trials that expands the SIRT inhibition knowledge and its effect on controlling clonal progression caused by genomic instability characteristics of these diseases. Finally, SIRTs represent potential molecular targets in the control of the effects caused by aging on the failures of the hematopoietic system that can lead to the involvement of hematological neoplasms.

SIRT1 suppresses pituitary tumor progression by downregulating PTTG1 expression

Although pituitary tumors are among the most common types of brain tumor, the underlying molecular mechanism of this disease remains obscure. To this end, the role of sirtuin 1 (SIRT1) in pituitary tumors was reported. The results of reverse transcription‑quantitative PCR and immunohistochemistry revealed that sirtuin 1 (SIRT1) expression was downregulated in the tumor tissues of patients with pituitary tumors. In vitro experiments of the present study demonstrated that SIRT1 upregulation suppressed pituitary tumor cell line growth, while SIRT1 downregulation demonstrated the opposite effect. Additionally, it was determined that the enzymatic activity of SIRT1 was required for its cellular function. A mechanistic experiment determined that SIRT1 negatively regulated pituitary tumor‑transforming gene 1 (PTTG1) expression through the deacetylation of histone (H)3 lysine (K)9ac at the promoter region of PTTG1. Moreover, H3K9ac levels at the PTTG1 promoter were determined to be an essential regulatory element for PTTG1 expression. Thus, it was concluded that the SIRT1/H3K9ac/PTTG1 axis contributed to pituitary tumor formation and may represent a potential therapeutic strategy.

Expression Landscape and Functional Roles of HOXA4 and HOXA5 in Lung Adenocarcinoma

BACKGROUND

The role of HOXA family genes in the occurrence and progression of a variety of human cancers has been scatteredly reported. However, there is no systematic study on the differential expression, prognostic significance and potential molecular mechanism of HOXA4 and HOXA5 in LUAD.

METHODS

In-house immunohistochemistry (IHC), multi-center microarrays, RT-qPCR and RNA-seq data were incorporated for comprehensively evaluating the expression and prognostic value of HOXA4 and HOXA5 in LUAD. The mechanism of HOXA4 and HOXA5 in the formation and development of LUAD was analyzed from multiple aspects of immune correlations, upstream transcriptional regulation, functional states of single cells and co-expressed gene network. The functional roles of HOXA4 and HOXA5 in LUAD were validated by in vitro experiments.

RESULTS

As a result, in 3201 LUAD samples and 2494 non-cancer lung samples, HOXA4 and HOXA5 were significantly downexpressed (P < 0.05). The aberrant expression of HOXA5 was significantly correlated with the clinical progression of LUAD (P < 0.05). HOXA5 showed remarkable prognostic value for LUAD patients (P < 0.05). The expression of HOXA4 and HOXA5 in LUAD were negatively correlated with tumor purity and positively correlated with the infiltration of various immune cells such as B cells, T cells and macrophages. HOXA4 and HOXA5 overexpression had notable inhibitory effect on the proliferation, migration and invasion of LUAD cells.

CONCLUSIONS

In conclusion, the identified downexpressed HOXA4 and HOXA5 had significant distinguishing ability for LUAD samples and affected the cellular functions of LUAD cells. The low expression of HOXA5 indicated worse overall survival of LUAD patients. Therefore, the two HOXA family genes especially HOXA5 may serve as potential biomarkers for LUAD.

MicroRNA-326 impairs chemotherapy resistance in non small cell lung cancer by suppressing histone deacetylase SIRT1-mediated HIF1α and elevating VEGFA

Compelling evidence has implicated the role of microRNAs (miRs or miRNAs) in lung cancer. Sirtuin-1 (SIRT1) is key contributor to the progression of non small cell lung cancer (NSCLC). This study was intended to investigate whether miR-326 affected NSCLC associated with SIRT1. miR-326 and SIRT1 expression in H460 cells and chemoresistant cells H460-R was measured by RT-qPCR. Dual luciferase reporter gene assay and RIP assay were used to identify and validate the relationship between miR-326 and SIRT1. Using gain- and loss-of-function approaches, we evaluated their effects on the chemoresistance of NSCLC cells. ChIP assay was used to detect binding of SIRT1 to the promoter of HIF1α gene, and the binding H3K9Ac to HIF1α, binding of H3K9Ac and HIF1α after silencing SIRT1, and binding HIF1α to VEGFA promoter. In vivo experiments were performed to validate the in vitro findings. MiR-326 expression was decreased while SIRT1 expression was increased in NSCLC cells. SIRT1 was a target of miR-326. MiR-326 inhibited the proliferation of chemotherapy-resistant NSCLC cells and promoted their apoptosis by suppressing SIRT1. In addition, SIRT1 promoted chemoresistance of NSCLC cell by elevating VEGFA expression. Through this mechanism, miR-326 reduced the chemoresistance, which was validated in vivo. Taken together, miR-326 represses SIRT1 through impeding HIF1α expression, thus hindering chemotherapy resistance in lung cancer. These findings provide an exquisite therapeutic target for NSCLC.

Emerging role of SIRT2 in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the most devastating cancer types, accounting for >80% of lung cancer cases. The median relative survival time of patients with NSCLC is <1 year. Lysine acetylation is a major post-translational modification that is required for various biological processes, and abnormal protein acetylation is associated with various diseases, including NSCLC. Protein deacetylases are currently considered cancer permissive partly due to malignant cells being sensitive to deacetylase inhibition. Sirtuin 2 (SIRT2), a primarily cytosolic nicotinamide adenine dinucleotide-dependent class III protein deacetylase, has been shown to catalyze the removal of acetyl groups from a wide range of proteins, including tubulin, ribonucleotide reductase regulatory subunit M2 and glucose-6-phosphate dehydrogenase. In addition, SIRT2 is also known to possess lysine fatty deacylation activity. Physiologically, SIRT2 serves as a regulator of the cell cycle and of cellular metabolism. It has been shown to play important roles in proliferation, migration and invasion during carcinogenesis. It is notable that both oncogenic and tumor suppressive functions of SIRT2 have been described in NSCLC and other cancer types, suggesting a context-specific role of SIRT2 in cancer progression. In addition, inhibition of SIRT2 exhibits a broad anticancer effect, indicating its potential as a therapeutic for NSCLC tumors with high expression of SIRT2. However, due to the diverse molecular and genetic characteristics of NSCLC, the context-specific function of SIRT2 remains to be determined. The current review investigated the functions of SIRT2 during NSCLC progression with regard to its regulation of metabolism, stem cell-like features and autophagy.

SIRT1/PGC-1α/PPAR-γ Correlate With Hypoxia-Induced Chemoresistance in Non-Small Cell Lung Cancer

Resistance is the major cause of treatment failure and disease progression in non-small cell lung cancer (NSCLC). There is evidence that hypoxia is a key microenvironmental stress associated with resistance to cisplatin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and immunotherapy in solid NSCLCs. Numerous studies have contributed to delineating the mechanisms underlying drug resistance in NSCLC; nevertheless, the mechanisms involved in the resistance associated with hypoxia-induced molecular metabolic adaptations in the microenvironment of NSCLC remain unclear. Studies have highlighted the importance of posttranslational regulation of molecular mediators in the control of mitochondrial function in response to hypoxia-induced metabolic adaptations. Hypoxia can upregulate the expression of sirtuin 1 (SIRT1) in a hypoxia-inducible factor (HIF)-dependent manner. SIRT1 is a stress-dependent metabolic sensor that can deacetylate some key transcriptional factors in both metabolism dependent and independent metabolic pathways such as HIF-1α, peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-gamma coactivator 1-alpha (PGC-1α) to affect mitochondrial function and biogenesis, which has a role in hypoxia-induced chemoresistance in NSCLC. Moreover, SIRT1 and HIF-1α can regulate both innate and adaptive immune responses through metabolism-dependent and -independent ways. The objective of this review is to delineate a possible SIRT1/PGC-1α/PPAR-γ signaling-related molecular metabolic mechanism underlying hypoxia-induced chemotherapy resistance in the NSCLC microenvironment. Targeting hypoxia-related metabolic adaptation may be an attractive therapeutic strategy for overcoming chemoresistance in NSCLC.

Serum Levels of Sirtuin-1 in Patients with Lung Cancer and its Association with Karnofsky Performance Status

Background:

Lung cancer is a major cause of cancer-related deaths worldwide. There are conflicting results regarding the role of sirtuin-1 in cancer. This study aimed to evaluate the serum sirtuin-1 levels in patients with lung cancer and its relationship with the quality of life based on Karnofsky performance statue scale (KPS).

Methods:

Serum sirtuin-1 levels were measured in 30 male patients with lung cancer and 50 healthy men. The two groups were matched for age. The difference between the serum levels of sirtuin-1 between the two groups and its relationship with KPS and other clinical parameters were evaluated. Data were analyzed by independent t-test and Pearson correlation, and P < 0.05 was considered as significant.

Results:

Sirtuin-1 levels were significantly lower in the patients in comparison with healthy subjects (P < 0.001). There was also a significant relationship between the serum level of sirtuin-1 with KPS (P < 0.001, r = 0.634), arterial oxygen saturation (P < 0.01, r = 0.470), and smoking history (P < 0.01, r = -0.330). In addition, the serum sirtuin-1 levels were significantly lower in adenocarcinoma than that in squamous cell carcinoma or small cell lung cancer (p < 0.001 and P < 0.05, respectively).

Conclusion:

The serum levels of sirtuin-1 were lower in patients with lung cancer. In addition, there was a significant correlation between serum levels of sirtuin-1 and KPS, O2 saturation, and smoking history. Further serological and histological studies seem to be necessary due to the existence of conflicting reports regarding sirtuin-1.

Molecular docking and anticancer activity determination of 5,10-dihydro-7,8-dimethyl alloxazine derived from lumichrome of riboflavin

 Cancer is accountable for the demise of numerous lives worldwide annually. In this research a derivative of lumichrome, 5,10-dihydro-7,8-dimethyl alloxazine was assessed for its anticancer property through docking study. It was appraised after performing molecular docking study of the 5,10-dihydro-7,8-dimethyl alloxazine, there was a strong interaction between multiple oncogenic target proteins like CDK2/CCNE2 (–8.5 kcal/mol), TDP2 (–8 kcal/mol), NAD-SIRT2 (–10.9 kcal/mol) and lung cancer and acute lymphoblastic leukemia (ALL). Additionally, according to ADMET analysis, the synthesized compound 5,10-dihydro-7,8-dimethyl alloxazine also has good physicochemical characteristics to be a drug candidate. Consequently, these verdicts will assist the development of a novel anti-lung cancer and anti-leukemic agent which will eventually improve the endurance of cancer patients.

MicroRNA-217 inhibits the proliferation and invasion, and promotes apoptosis of non-small cell lung cancer cells by targeting sirtuin 1

Non-small cell lung cancer (NSCLC) is a common malignancy worldwide. MicroRNA (miR)-217 and sirtuin 1 (SIRT1) have been reported to play significant roles in different types of cancer, such as osteosarcoma and prostate cancer; however, the association between miR-217 and SIRT1 in the cell proliferation, apoptosis and invasion of NSCLC remain unknown. Thus, the present study aimed to investigate the roles of miR-217 and SIRT1 in NSCLC. The expression levels of miR-217 and SIRT1 were detected via reverse transcription-quantitative (RT-q)PCR and western blot analyses. The effect of miR-217 on A549 and H1299 cell proliferation, apoptosis and invasion was assessed via the Cell Counting Kit-8, flow cytometry and Transwell assays, respectively. In addition, the association between SIRT1 and miR-217 was predicted using the TargetScan database, and verified via the dual-luciferase reporter assay, and RT-qPCR and western blot analyses. The results demonstrated that miR-217 expression was significantly downregulated, while SIRT1 expression was significantly upregulated in A549 and H1299 cells compared with the human bronchial epithelial cells. Furthermore, transfection with miR-217 mimic significantly inhibited A549 and H1299 cell proliferation and invasion, and induced A549 and H1299 cell apoptosis. The results of the dual-luciferase reporter assay and western blot analysis confirmed that SIRT1 is a target gene of miR-217. In addition, miR-217 inhibited the activation of AMP-activated protein kinase (AMPK) and mTOR signaling. Taken together, the results of the present study suggest that miR-217 inhibits A549 and H1299 cell proliferation and invasion, and induces A549 and H1299 cell apoptosis by targeting SIRT1 and inactivating the SIRT1-mediated AMPK/mTOR signaling pathway. Thus, miR-217 may be used as a potential therapeutic target for the treatment of patients with NSCLC.

Circular and linear: a tale of aptamer selection for the activation of SIRT1 to induce death in cancer cells

It is a challenge to select the right target to treat conditions without affecting non-diseased cells. Cancer belongs to the top 10 causes of death in the world and it remains difficult to treat. Amongst cancer emerging targets, silent information regulator 1 (SIRT1) - a histone deacetylase - has shown many roles in cancer, ageing and metabolism. Here we report novel SIRT1 ligands that bind and modulate the activity of SIRT1 within cells and enhance its enzymatic activity. We developed a modified aptamer capable of binding to and forming a complex with SIRT1. Our ligands are aptamers, they can be made of DNA or RNA oligonucleotides, their binding domain can recognise a target with very high affinity and specificity. We used the systematic evolution of ligands by exponential enrichment (SELEX) technique to develop circular and linear aptamers selectively binding to SIRT1. Cellular consequences of the interaction were monitored by fluorescence microscopy, cell viability assay, stability and enzymatic assays. Our results indicate that from our pool of aptamers, circular AC3 penetrates cancerous cells and is recruited to modulate the SIRT1 activity. This modulation of SIRT1 resulted in anticancer activity on different cancer cell lines. Furthermore, this modified aptamer showed no toxicity on one non-cancerous cell line and was stable in human plasma. We have demonstrated that aptamers are efficient tools for localisation of internal cell targets, and in this particular case, anticancer activity through modulation of SIRT1.

ROS-Induced SIRT2 Upregulation Contributes to Cisplatin Sensitivity in Ovarian Cancer

Cisplatin resistance remains a significant obstacle for improving the clinical outcome of ovarian cancer patients. Recent studies have demonstrated that cisplatin is an important inducer of intracellullar reactive oxygen species (ROS), triggering cancer cell death. Sirtuin 2 (SIRT2), a member of class III NAD⁺ dependent histone deacetylases (HDACs), has been reported to be involved in regulating cancer hallmarks including drug response. In this study, we aimed to identify the role of SIRT2 in oxidative stress and cisplatin response in cancer. Two ovarian cancer cell lines featuring different sensitivities to cisplatin were used in this study. We found different expression patterns of SIRT2 in cisplatin-sensitive (A2780/S) and cisplatin-resistant (A2780/CP) cancer cells with cisplatin treatment, where SIRT2 expression was augmented only in A2780/S cells. Furthermore, cisplatin-induced ROS generation was responsible for the upregulation of SIRT2 in A2780/S cells, whereas overexpression of SIRT2 significantly enhanced the sensitivity of cisplatin-resistant counterpart cells to cisplatin. Our study proposes that targeting SIRT2 may provide new strategies to potentiate platinum-based chemotherapy in ovarian cancer patients.

The Clinical Significance of SIRT2 in Malignancies: A Tumor Suppressor or an Oncogene?

Sirtuin 2 (SIRT2) is a member of the sirtuin protein family. It is a Class III histone deacetylase (HDACs) and predominantly localized to the cytosol. SIRT2 deacetylates histones and a number of non-histone proteins and plays a pivotal role in various physiologic processes. Previously, SIRT2 has been considered indispensable during carcinogenesis; however, there is now a significant controversy regarding whether SIRT2 is an oncogene or a tumor suppressor. The purpose of this review is to summarize the physiological functions of SIRT2 and its mechanisms in cancer. We will focus on five malignancies (breast cancer, non-small cell lung cancer, hepatocellular carcinoma, colorectal cancer, and glioma) to describe the current status of SIRT2 research and discuss the clinical evaluation of SIRT2 expression and the use of SIRT2 inhibitors.

Cytoplasm-localized SIRT1 downregulation attenuates apoptosis and cell cycle arrest in cisplatin-resistant lung cancer A549 cells

Objective: We propose that sirtuin (SIRT) may induce a pro-apoptotic effect by deacetylating transcription factors in A549 cells: depletion of sirtuin-1 (SIRT1) induced cell cycle arrest in cisplatin-resistant A549 (A549/CADD) cells.

Methods: Protein and mRNA levels of SIRT1 were investigated using western blot and RT-PCR. In A549 and A549/CADD cells, the cytotoxicity of cisplatin administration was evaluated by MTT assay, proliferation was measured by ECIS, and the cell cycle distribution was analyzed using FACS. Cells were transfected with pcDNA3.1-Myc-SIRT1 or pcDNA3.1-Myc-Control vectors to analyze the impact of SIRT-1 on cisplatin induced drug resistance. SIRT1 localization was studied using immunofluorescence analysis. In addition, immunoprecipitation and 20S proteasome activity assay were performed to examine the relationship of SIRT1 with the proteasome complex.

Results: A549/CADD cells exhibited a mesenchymal-like cell characteristic. SIRT1 expression was markedly decreased in A549/CADD cells. We observed that cisplatin regulates p53 stability through the depletion of ubiquitination following SIRT1 downregulation. Furthermore, cisplatin treatment increased proteasomal activity and significantly decreased cytoplasmic SIRT1 protein levels in A549/CADD cells.

Conclusion: In this study, we found SIRT1 to be depleted in A549/CADD cells and also determined the underlying resistance mechanism which may act as novel therapeutic targets in overcoming drug resistance.

Impact of Sirtuin Enzymes on the Altered Metabolic Phenotype of Malignantly Transformed Cells

Sirtuins compose a unique collection of histone deacetylase enzymes that have a wide variety of enzymatic activities and regulate diverse cell functions such as cellular metabolism, longevity and energy homeostasis, mitochondrial function, and biogenesis. Impaired sirtuin functions or alterations of their expression levels may result in several pathological conditions and contribute to the altered metabolic phenotype of malignantly transformed cells in a significant manner. In the twenty-first century, principles of personalized anticancer treatment need to involve not only the evaluation of changes of the genetic material, but also the mapping of epigenetic and metabolic alterations, to both of which the contribution of sirtuin enzymes is fundamental. Since sirtuins are central players in the maintenance of cellular energy and metabolic homeostasis, they are key elements in the development of metabolic transformation of cancer cells referred to as the Warburg effect. Although its most well-known features are enhanced glycolysis and excessive lactate production, Warburg effect has several aspects involving both carbohydrate, lipid, and amino acid metabolism, among which different tumor types have different preferences. Therefore, energy supply of cancer cells can be impaired by a growing number of antimetabolite agents, for which appropriate vectors are strongly needed. However, data are controversial about their tumor suppressor or oncogenic properties, the biological effects of sirtuin enzymes strongly depend on the tissue microenvironment (TME) in which they are expressed. Immune cells are regarded as key players of TME. Sirtuins regulate the survival, activation, metabolism, and mitochondrial function of these cells, therefore, they are not only single elements, but key regulators of the network that determines anticancer immunity. Altered metabolism of tumor cells induces changes in the gene expression pattern of cells in TME, due to altered concentrations of metabolite cofactors of epigenetic modifiers including sirtuins. In summary, epigenetic and metabolic alterations in malignant diseases are influenced by sirtuins in a significant manner, and should be treated in a personalized approach. Since they often develop in early stages of cancer, broad examination of these alterations is required at time of the diagnosis in order to provide a personalized combination of distinct therapeutic agents.

SIRT2: Controversy and multiple roles in disease and physiology

Sirtuin 2 (SIRT2) is an NAD+-dependent deacetylase that was under studied compared to other sirtuin family members. SIRT2 is the only sirtuin protein which is predominantly found in the cytoplasm but is also found in the mitochondria and in the nucleus. Recently, accumulating evidence has uncovered a growing number of substrates and additional detailed functions of SIRT2 in a wide range of biological processes, marking its crucial role. Here, we give a comprehensive profile of the crucial physiological functions of SIRT2 and its role in neurological diseases, cancers, and other diseases. This review summarizes the functions of SIRT2 in the nervous system, mitosis regulation, genome integrity, cell differentiation, cell homeostasis, aging, infection, inflammation, oxidative stress, and autophagy. SIRT2 inhibition rescues neurodegenerative disease symptoms and hence SIRT2 is a potential therapeutic target for neurodegenerative disease. SIRT2 is undoubtedly dysfunctional in cancers and plays a dual-faced role in different types of cancers, and although its mechanism is unresolved, SIRT2 remains a promising therapeutic target for certain cancers. In future, the continued rapid growth in SIRT2 research will help clarify its role in human health and disease, and promote the progress of this target in clinical practice.

Immunohistochemistry and clinical value of sirtuin 2 in non-metastasized non-small cell lung cancer

Background

This study aimed to define whether sirtuin 2 (SIRT2) expression levels are related to the prognosis of non-small cell lung cancer (NSCLC) patients.

Methods

A survival analysis was carried out using the Kaplan-Meier (KM) plotter database. Immunohistochemical staining was performed and KM's method was used to estimate the survival rates for SIRT2 expression in 72 clinical samples.

Results

A survival analysis of 1,926 NSCLC patients showed that patients with low SIRT2 expression levels had significantly longer overall survival (OS) than those with high SIRT2 expression levels (P=0.0077; HR =1.19). In 72 non-metastasized NSCLC tissues, the positive rate of SIRT2 expression was 90.3% (65/72), among which, the positive expression rates of squamous cell carcinoma (SCC) and adenocarcinoma (ADC) were 96.4% (27/28) and 85.4% (35/41), respectively. Survival analysis showed that patients with low SIRT2 expression levels had significantly longer median survival time (MST) than those with high SIRT2 expression levels (15.0 versus 14.0 months, P=0.029). Furthermore, the results of subgroup analysis demonstrated patients with low SIRT2 expression levels had significantly longer survival time in ADC group (15.0 versus 12.0 months, P=0.022), but there wasn't significant difference in SCC group (15.0 versus 14.0 months, P=0.932). A multivariate Cox proportional hazards model, which included gender, age, TNM stage, differentiation and SIRT2 expression, showed that SIRT2 expression was an independent factor related to prognosis [HR =1.903, 95% confidence interval (95% CI): 1.085-3.339, P=0.025].

Conclusions

SIRT2 expression levels were significantly related to the survival time of patients with lung ADC but not SCC. Our study indicated SIRT2 was perhaps a specific prognostic biomarker for non-metastasized lung ADC.

Acetylation regulates ribonucleotide reductase activity and cancer cell growth

Ribonucleotide reductase (RNR) catalyzes the de novo synthesis of deoxyribonucleoside diphosphates (dNDPs) to provide dNTP precursors for DNA synthesis. Here, we report that acetylation and deacetylation of the RRM2 subunit of RNR acts as a molecular switch that impacts RNR activity, dNTP synthesis, and DNA replication fork progression. Acetylation of RRM2 at K95 abrogates RNR activity by disrupting its homodimer assembly. RRM2 is directly acetylated by KAT7, and deacetylated by Sirt2, respectively. Sirt2, which level peak in S phase, sustains RNR activity at or above a threshold level required for dNTPs synthesis. We also find that radiation or camptothecin-induced DNA damage promotes RRM2 deacetylation by enhancing Sirt2-RRM2 interaction. Acetylation of RRM2 at K95 results in the reduction of the dNTP pool, DNA replication fork stalling, and the suppression of tumor cell growth in vitro and in vivo. This study therefore identifies acetylation as a regulatory mechanism governing RNR activity.

Collateral sensitivity of drug-resistant ABCB5- and mutation-activated EGFR overexpressing cells towards resveratrol due to modulation of SIRT1 expression

BACKGROUND

In the drug discovery field, natural products deemed a precious source of novel lead compounds. They have the ability to bypass or overcome multidrug resistance (MDR) in cancer cells.

PURPOSE

In this study, the natural polyphenolic stilbene resveratrol (RES) has been studied for its cytotoxic activity toward MDR cancer cells.

METHODS

Resazurin assay was used to investigate the cytotoxicity of RES not only against a panel of drug-resistant cancer cells overexpressing P-glycoprotein/ABCB1, BCRP/ABCG2, ABCB5 (ATP-binding cassette transporters), but also mutation-activated EGFR. The assessment of proteins expression was done by Western blot analysis. COMPARE and hierarchical cluster analyses were applied to identify, which genes correlate with sensitivity or resistance to RES. The NF-κB activation was evaluated using NF-kB reporter cells assay.

RESULTS

Interestingly, MDR cells overexpressing ABCB5 and mutation-activated EGFR were collateral sensitive (CS) to RES. Our immunoblotting analysis highlighted that CS may be attributed to RES-induced sirtuin 1 (SIRT1) overexpression. Indeed, the SIRT1 inhibitor, sirtinol completely abolished CS to RES, indicating a causative role of SIRT1 for CS to RES. In addition, COMPARE and hierarchical cluster analyses of transcriptomic data indicated genes associated with diverse cellular mechanisms ranging from the immune response, inflammation signaling, and microtubule formation to cell migration. Searching for transcription factor binding motifs in the promoters of these genes pointed to NF-κB as one of the master regulators related to RES activity.

CONCLUSION

The findings demonstrate that RES alone or in combination with established chemotherapeutic agents might overcome the refractory tumors. This information may be immensely useful for the development of personalized treatment.

SIRT1: a potential tumour biomarker and therapeutic target

SIRT1, which is highly homologous to yeast silent information regulator 2, has recently garnered tremendous attention because of its various regulatory effects in several pathological conditions. Numerous studies have found that SIRT1 is highly expressed in a broad range of tumours compared with the paracancerous tissue. However, the role of SIRT1 in malignancies has yet to be systematically elucidated, and its use as a promising biomarker or therapeutic target for tumours has not been well-reported. Herein, we focus on the roles of SIRT1 in cancers and summarise the potential use of SIRT1 as a promising tumour biomarker or therapeutic target.

MicroRNA let‑7d‑5p rescues ovarian cancer cell apoptosis and restores chemosensitivity by regulating the p53 signaling pathway via HMGA1

Ovarian cancer (OC) is the gynecological malignancy type with the highest mortality rate in females. The regulatory effect of microRNAs (miRs) on their target genes serves a key role in tumor development. Therefore, in the present study, whether miR let‑7d‑5p targeting high mobility group A1 (HMGA1) regulated biological characteristics and chemosensitivity of OC cells by mediating the p53 signaling pathway was investigated. The let‑7d‑5p level was detected in OC tissues and adjacent normal tissues, followed by detection in OC cell lines SKOV3, A2780, OVCAR‑3 and CaOV3, and human normal ovarian epithelial cell line (IOSE‑80), in order to select the OC cell line for the following experiments. Subsequently, OC cells were treated with the let‑7d‑5p mimic, siHMGA1 and Tenovin‑1. The targeting association between let‑7d‑5p and HMGA1 was then examined, and the OC cell viability, migration, cycle and apoptosis were evaluated. Subsequently, the chemosensitivity of OC cells to cisplatin was verified. Finally, expression levels of let‑7d‑5p, HMGA1, p21, B‑cell lymphoma‑2 (Bcl‑2)‑associated X (Bax), p27, p53 wild‑type (p53wt), p53 mutated (p53mut), proliferating cell nuclear antigen (PCNA), cyclin‑dependent kinase 2 (CDK2), matrix metallopeptidase (MMP)2, MMP9 and Bcl‑2 were determined. As demonstrated in the results, let‑7d‑5p expression was low in OC tissues and had an increased reduction in the OVCAR‑3 cell line. HMGA1 was confirmed as a target of let‑7d‑5p, and its expression was also silenced by let‑7d‑5p. let‑7d‑5p repressed OC cell viability, migration, cell cycle progression and apoptosis, while it promoted the chemosensitivity of OC cells to cisplatin by targeting HMGA1. The expression of let‑7d‑5p, p21, Bax, p27 and p53wt was increased, while that of HMGA1, p53mut, PCNA, CDK2, MMP2, MMP9 and Bcl‑2 was reduced following cell transfection. The results in the present study provided evidence that let‑7d‑5p may suppress proliferation, and facilitate apoptosis and cisplatin chemosensitivity of OC cells by silencing HMGA1 via the p53 signaling pathway.

Dual Tumor Suppressor and Tumor Promoter Action of Sirtuins in Determining Malignant Phenotype

Sirtuins (SIRTs), class III histone deacetylases, are differentially expressed in several human cancers, where they display both oncogenic and tumor-suppressive properties depending on cellular context and experimental conditions. SIRTs are involved in many important biological processes and play a critical role in cancer initiation, promotion, and progression. A growing body of evidence indicates the involvement of SIRTs in regulating three important tumor processes: epithelial-to-mesenchymal transition (EMT), invasion, and metastasis. Many SIRTs are responsible for cellular metabolic reprogramming and drug resistance by inactivating cell death pathways and promoting uncontrolled proliferation. In this review, we summarize current knowledge on the role of SIRTs in cancer and discuss their puzzling dual function as tumor suppressors and tumor promoters, important for the future development of novel tailored SIRT-based cancer therapies.

Survival and Clinicopathological Significance of SIRT1 Expression in Cancers: A Meta-Analysis

Background: Silent information regulator 2 homolog 1 (SIRT1) is an evolutionarily conserved enzymes with nicotinamide adenine dinucleotide (NAD)⁺-dependent deacetylase activity. SIRT1 is involved in a large variety of cellular processes, such as genomic stability, energy metabolism, senescence, gene transcription, and oxidative stress. SIRT1 has long been recognized as both a tumor promoter and tumor suppressor. Its prognostic role in cancers remains controversial. Methods: A meta-analysis of 13,138 subjects in 63 articles from PubMed, EMBASE, and Cochrane Library was performed to evaluate survival and clinicopathological significance of SIRT1 expression in various cancers. Results: The pooled results of meta-analysis showed that elevated expression of SIRT1 implies a poor overall survival (OS) of cancer patients [Hazard Ratio (HR) = 1.566, 95% CI: 1.293-1.895, P < 0.0001], disease free survival (DFS) (HR = 1.631, 95% CI: 1.250-2.130, P = 0.0003), event free survival (EFS) (HR = 2.534, 95% CI: 1.602-4.009, P = 0.0001), and progress-free survival (PFS) (HR = 3.325 95% CI: 2.762-4.003, P < 0.0001). Elevated SIRT1 level was associated with tumor stage [Relative Risk (RR) = 1.299, 95% CI: 1.114-1.514, P = 0.0008], lymph node metastasis (RR = 1.172, 95% CI: 1.010-1.360, P = 0.0363), and distant metastasis (RR = 1.562, 95% CI: 1.022-2.387, P = 0.0392). Meta-regression and subgroup analysis revealed that ethnic background has influence on the role of SIRT1 expression in predicting survival and clinicopathological characteristics of cancers. Overexpression of SIRT1 predicted a worse OS and higher TNM stage and lymphatic metastasis in Asian population especially in China. Conclusion: Our data suggested that elevated expression of SIRT1 predicted a poor OS, DFS, EFS, PFS, but not for recurrence-free survival (RFS) and cancer-specific survival (CCS). SIRT1 overexpression was associated with higher tumor stage, lymph node metastasis, and distant metastasis. SIRT1-mediated molecular events and biological processes could be an underlying mechanism for metastasis and SIRT1 is a therapeutic target for inhibiting metastasis, leading to good prognosis.

5 protein-based signature for resectable lung squamous cell carcinoma improves the prognostic performance of the TNM staging

INTRODUCTION

Prognostic biomarkers have been very elusive in the lung squamous cell carcinoma (SCC) and none is currently being used in the clinical setting. We aimed to identify and validate the clinical utility of a protein-based prognostic signature to stratify patients with early lung SCC according to their risk of recurrence or death.

METHODS

Patients were staged following the new International Association for the Study of Lung Cancer (IASLC) staging criteria (eighth edition, 2018). Three independent retrospective cohorts of 117, 96 and 105 patients with lung SCC were analysed to develop and validate a prognostic signature based on immunohistochemistry for five proteins.

RESULTS

We identified a five protein-based signature whose prognostic index (PI) was an independent and significant predictor of disease-free survival (DFS) (p<0.001; HR=4.06, 95% CI 2.18 to 7.56) and overall survival (OS) (p=0.004; HR=2.38, 95% CI 1.32 to 4.31). The prognostic capability of PI was confirmed in an external multi-institutional cohort for DFS (p=0.042; HR=2.01, 95% CI 1.03 to 3.94) and for OS (p=0.031; HR=2.29, 95% CI 1.08 to 4.86). Moreover, PI added complementary information to the newly established IASLC TNM 8th edition staging system. A combined prognostic model including both molecular and anatomical (TNM) criteria improved the risk stratification in both cohorts (p<0.05).

CONCLUSION

We have identified and validated a clinically feasible protein-based prognostic model that complements the updated TNM system allowing more accurate risk stratification. This signature may be used as an advantageous tool to improve the clinical management of the patients, allowing the reduction of lung SCC mortality through a more accurate knowledge of the patient's potential outcome.

The effect of centromere protein U silencing by lentiviral mediated RNA interference on the proliferation and apoptosis of breast cancer

Centromere protein U (CENPU) is a novel transcriptional repressor that is associated with different types of cancer. However, its function in breast cancer is poorly understood. In the present study, it was identified that CENPU was highly expressed in breast cancer tissues compared with expression in normal breast tissues (P=0.001). Furthermore, the CENPU mRNA level in tumors was often elevated, compared with the matched adjacent normal breast cancer tissue specimens in the dataset from The Cancer Genome Atlas database (n=106; P<0.001). To understand the function of CENPU in human breast carcinogenesis, its effects on the proliferation, apoptosis and cell cycle progression of MDA-MB-231 cells were examined using the lentiviral-mediated CENPU knockdown approach. The RNA and protein expression levels in the transfected cells were monitored using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The mRNA and protein expression levels of the CENPU gene were significantly lower in the CENPU-shRNA transfected cells than in the control (P<0.01), indicating successful gene expression knockdown. Post-transfection, cell counting and MTT analysis revealed that the proliferation activity was significantly suppressed in CENPU knockdown cells relative to the control (P<0.01). Additionally, fluorescence activated cell sorting analysis revealed that the (G2+S) phase fraction was significantly declined in CENPU knockdown cells relative to the control; while the G1 phase fraction was significantly increased (P<0.01) and the percentage of the apoptotic cells was significantly increased (P<0.01). In conclusion, downregulation of CENPU gene expression may inhibit cell proliferation and cell cycle progression, and increase the apoptosis of the breast cancer cells. These results suggested a possible function of this protein in breast cancer pathogenesis and prognosis.

Associations of sirtuins with clinicopathological parameters and prognosis in non-small cell lung cancer

BACKGROUND

Lung cancer is the leading cause of cancer-related death worldwide and it is critical to discover specific biomarkers to provide better individualized treatment and subsequently better prognosis. The sirtuins (SIRT1-7) have been reported to be involved in cancers including non-small cell lung cancer (NCSLC), however, the results are not consistent and not all the seven sirtuins are explored and compared.

METHODS

TCGA data was downloaded and used to investigate and compare the associations of sirtuins mRNA levels with clinicopathological parameters and prognosis in NSCLC.

RESULTS

Our results suggested SIRT1, SIRT3, SIRT4, and SIRT7 were highly expressed in adeno-carcinoma (ADC) patients and female patients while SIRT5 were highly expressed in squamous cell carcinoma (SCC) patients and male patients. Associations of high SIRT7 with younger onset age, high SIRT1 with distant metastasis and low T stage, and high SIRT4 with high T stage and TNM stage were also found. Kaplan-Meier plot curves and univariate Cox proportional regression analyses indicated that high SIRT2, SIRT4, and SIRT6 expressions were associated with longer overall survival (OS) time. Multivariate analyses indicated that SIRT2 and SIRT6 were still associated with OS. For recurrence-free survival (RFS), high SIRT1 expression was significantly associated with shorter RFS time while high SIRT2-3 and SIRT5-7 expressions were associated with longer RFS time in univariate analyses. After adjusting the confounding factors, significant associations were still found in SIRT1-2 and SIRT5-7 but not in SIRT3. We also stratified the patients by combining SIRT1 and SIRT2 and revealed that the combination of SIRT1 and SIRT2 was a better prediction model for RFS in NSCLC. To preliminarily understand the potential mechanisms of sirtuins in NSCLC carcinogenesis, the genes co-expressed with sirtuins were analyzed and annotated.

CONCLUSION

sirtuins might be the potential therapy targets and prognostic biomarkers in NSCLC.

Sirt1 protects from K-Ras-driven lung carcinogenesis

The NAD+-dependent deacetylase SIRT1 can be oncogenic or tumor suppressive depending on the tissue. Little is known about the role of SIRT1 in non-small cell lung carcinoma (NSCLC), one of the deadliest cancers, that is frequently associated with mutated K-RAS Therefore, we investigated the effect of SIRT1 on K-RAS-driven lung carcinogenesis. We report that SIRT1 protein levels are downregulated by oncogenic K-RAS in a MEK and PI3K-dependent manner in mouse embryo fibroblasts (MEFs), and in human lung adenocarcinoma cell lines. Furthermore, Sirt1 overexpression in mice delays the appearance of K-RasG12V-driven lung adenocarcinomas, reducing the number and size of carcinomas at the time of death and extending survival. Consistently, lower levels of SIRT1 are associated with worse prognosis in human NSCLCs. Mechanistically, analysis of mouse Sirt1-Tg pneumocytes, isolated shortly after K-RasG12V activation, reveals that Sirt1 overexpression alters pathways involved in tumor development: proliferation, apoptosis, or extracellular matrix organization. Our work demonstrates a tumor suppressive role of SIRT1 in the development of K-RAS-driven lung adenocarcinomas in mice and humans, suggesting that the SIRT1-K-RAS axis could be a therapeutic target for NSCLCs.

Dichloroacetic acid (DCA) synergizes with the SIRT2 inhibitor Sirtinol and AGK2 to enhance anti-tumor efficacy in non-small cell lung cancer

Combination chemotherapy is a potentially promising approach to enhance anticancer activity, overcome drug resistance, and improve disease-free and overall survival. The current study investigates the antitumor activity of sodium dichloroacetic acid (DCA) in combination with SIRT2 inhibitor Sirtinol and AGK2. We found that combining DCA with Sirtinol produced a synergistic therapeutic benefit in A549 and H1299 NSCLC cells in vitro and in a mouse A549 xenograft model. Synergistic potentiation of oxidative phosphorylation (OXPHOS) was observed, including decreased glucose consumption, decreased lactate production, increased OCR and increased ROS generation, possibly via co-targeting pyruvate dehydrogenase alpha 1(PDHA1). Mechanically, AGK2 and Sirtinol were found to increase the lysine-acetylation and decrease the serine-phosphorylation of PDHA1, which enabled the two inhibitors to synergize with DCA to further activate PDHA1. Besides, a AMPKα-ROS feed-forward loop was notably activated after the combined treatments compared with mono-therapy. Our results indicate that the combination of DCA and SIRT2 inhibitor may provide a promising therapeutic strategy to effectively kill cancer cells.

A novel protein-based prognostic signature improves risk stratification to guide clinical management in early-stage lung adenocarcinoma patients

Each of the pathological stages (I-IIIa) of surgically resected non-small-cell lung cancer has hidden biological heterogeneity, manifested as heterogeneous outcomes within each stage. Thus, the finding of robust and precise molecular classifiers with which to assess individual patient risk is an unmet medical need. Here, we identified and validated the clinical utility of a new prognostic signature based on three proteins (BRCA1, QKI, and SLC2A1) to stratify early-stage lung adenocarcinoma patients according to their risk of recurrence or death. Patients were staged according to the new International Association for the Study of Lung Cancer (IASLC) staging criteria (8th edition, 2018). A test cohort (n = 239) was used to assess the value of this new prognostic index (PI) based on the three proteins. The prognostic signature was developed by Cox regression with the use of stringent statistical criteria (TRIPOD: Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis). The model resulted in a highly significant predictor of 5-year outcome for disease-free survival (p < 0.001) and overall survival (p < 0.001). The prognostic ability of the model was externally validated in an independent multi-institutional cohort of patients (n = 114, p = 0.021). We also demonstrated that this molecular classifier adds relevant information to the gold standard TNM-based pathological staging, with a highly significant improvement of the likelihood ratio. We subsequently developed a combined PI including both the molecular and the pathological data that improved the risk stratification in both cohorts (p ≤ 0.001). Moreover, the signature may help to select stage I-IIA patients who might benefit from adjuvant chemotherapy. In summary, this protein-based signature accurately identifies those patients with a high risk of recurrence and death, and adds further prognostic information to the TNM-based clinical staging, even when the new IASLC 8th edition staging criteria are applied. More importantly, it may be a valuable tool for selecting patients for adjuvant therapy. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epigenome-Based Precision Medicine in Lung Cancer

Lung cancer is the leading cause of cancer-related deaths in the world. Despite significant advances in the early detection and treatment of the disease, the prognosis remains poor, with an overall 5-year survival rate ranging from 15% to 20%. This poor prognosis results largely from early micrometastatic spread of cancer cells to nearby lymph nodes or tissues and partially from early recurrence after curative surgical resection. Recently, precision medicines that target potential oncogenic driver mutations have been approved to treat lung cancer. However, some lung cancer patients do not have targetable mutations, and many patients develop resistance to targeted therapy. Tumor heterogeneity and mutational density are also challenges in treating lung cancer, which underscores the need for developing alternative therapeutic strategies for treating lung cancer. Epigenetic therapy may circumvent the problems of tumor heterogeneity and drug resistance by affecting the expression of several hundred target genes. This review highlights precision medicine using an innovative approach of epigenetic priming prior to conventional standard therapy or targeted cancer therapy in lung cancer.

The anti-cancer effects and mechanisms of Scutellaria barbata D. Don on CL1-5 lung cancer cells

Lung cancer, with a poor prognosis and resistance to chemotherapy, is the most common malignant tumor and has the highest mortality rate worldwide. Scutellaria barbata D. Don (SB), which is derived from the dried whole plant of Labiatae, is a well-known anti-inflammatory and anti-cancer herb. The aim of this study was to examine the anti-cancer effects and precise regulatory mechanisms of SB in CL1-5 lung cancer cells. In an in vitro assay, we found that the anti-tumor mechanism of SB was due to P38/SIRT1-regulated cell apoptosis through G2/M phase arrest and ER stress-, intrinsic mitochondrial-, and extrinsic FAS/FASL-mediated pathways. Autophagy also plays a key role in SB-induced CL1-5 cell cytotoxicity. In addition, SB exerts additive effects with etoposide or cisplatin in lung cancer cells. In an in vivo assay, we found that SB significantly reduces tumor size with decreased proliferation and angiogenesis, as well as increased apoptosis and autophagy in CL1-5 tumor-bearing mice. These findings provided experimental evidence for the application of SB in the treatment of lung cancer.

The SIRT2 Deacetylase Stabilizes Slug to Control Malignancy of Basal-like Breast Cancer

Overabundance of Slug protein is common in human cancer and represents an important determinant underlying the aggressiveness of basal-like breast cancer (BLBC). Despite its importance, this transcription factor is rarely mutated in BLBC, and the mechanism of its deregulation in cancer remains unknown. Here, we report that Slug undergoes acetylation-dependent protein degradation and identify the deacetylase SIRT2 as a key mediator of this post-translational mechanism. SIRT2 inhibition rapidly destabilizes Slug, whereas SIRT2 overexpression extends Slug stability. We show that SIRT2 deacetylates Slug protein at lysine residue K116 to prevent Slug degradation. Interestingly, SIRT2 is frequently amplified and highly expressed in BLBC. Genetic depletion and pharmacological inactivation of SIRT2 in BLBC cells reverse Slug stabilization, cause the loss of clinically relevant pathological features of BLBC, and inhibit tumor growth. Our results suggest that targeting SIRT2 may be a rational strategy for diminishing Slug abundance and its associated malignant traits in BLBC.

Effect of Sirtuin 1 inhibition on matrix metalloproteinase 2 and Forkhead box O3a expression in breast cancer cells

Breast cancer is the most common invasive cancer in women worldwide. Sirtuin 1 (SIRT1) has recently been shown to have implications in regulating cancer cell growth and apoptosis. SIRT1 regulates Forkhead box O3a (FOXO3a) by both inhibiting FOXO3-induced apoptosis and potentiating the ability of FOXO3a to resist oxidative stress. Matrix metalloproteinase 2 (MMP2) participates in tumor invasion and metastasis by degrading extracellular matrix. SIRT1 up regulates MMP2 expression by its deacetylation activity. This study aimed to investigate the expression of SIRT1, FOXO3a and MMP2 in breast tissues of women with breast cancer. In addition, the effect of SIRT1 inhibition on both FOXO3a and MMP2 expression in breast cancer (MCF-7) cells was assessed. The expression levels of SIRT1, FOXO3a and MMP2 in the breast tissues were determined by real-time PCR in 60 patients with malignant tumor and in 24 patients with benign tumors. After SIRT1 inhibition, protein levels of SIRT1 and FOXO3a were assessed by Western Blot and levels of MMP2 by ELISA in MCF-7 cells. The expression levels of SIRT1, FOXO3a and MMP2 were significantly higher in breast cancer tissues compared to in benign breast tumor and adjacent normal tissues. SIRT1, MMP2 and FOXO3a expression were associated directly with each other. SIRT1 inhibition suppresses MMP2 and FOXO3a expression compared to control MCF7. Sirtinol (SIRT1 inhibitor) effectively induced inhibition of MMP2 and FOXO3a expression in MCF-7 cells, indicating the promising therapeutic strategy of targeting SIRT1 for breast cancer.

3D-cultivation of NSCLC cell lines induce gene expression alterations of key cancer-associated pathways and mimic in-vivo conditions

This work evaluated gene expression differences between a hanging-drop 3D NSCLC model and 2D cell cultures and their in-vivo relevance by comparison to patient-derived data from The Cancer Genome Atlas.

Gene expression of 2D and 3D cultures for Colo699 and A549 were assessed using Affymetrix HuGene 1.0 ST gene chips. Biostatistical analyses tested for reproducibility, comparability and significant differences in gene expression profiles between cell lines, experiments and culture methods.

The analyses revealed a high interassay correlation within specific culture systems proving a high validity. 979 genes were altered in A549 and 1106 in Colo699 cells due to 3D cultivation. The overlap of changed genes between the cell lines was small (149), but the involved pathways in the reactome and GO- analyses showed a high overlap with DNA methylation, cell cycle, SIRT1, PKN1 pathway, DNA repair and oxidative stress as well known cancer-associated representatives. Additional specific GSEA-analyses revealed changes in immunologic and endothelial cell proliferation pathways, whereas hypoxic, EMT and angiogenic pathways were downregulated.

Gene enrichment analyses showed 3D-induced gene up-regulations in the cell lines 38 to be represented in in-vivo samples of NSCLC patients using data of The Cancer Genome Atlas.

Thus, our 3D NSCLC model might provide a tool for early drug development and investigation of microenvironment-associated mechanisms. However, this work also highlights the need for further individualization and model adaption to address remaining challenges.

Co-ordinated overexpression of SIRT1 and STAT3 is associated with poor survival outcome in gastric cancer patients

In many gastric cancer patients, the disease is diagnosed in an advanced stage and therefore the mortality levels are high. Because there is a need to identify novel early diagnostic and prognostic biomarkers, we tested whether SIRT1 and STAT3 are good candidates. Towards this, we used patient tissues representing different stages of gastric cancer including gastric pre-cancerous lesions, early gastric cancer, and advanced gastric cancer, and probed SIRT1, STAT3 and phosphorylated STAT3 (pSTAT3) levels using immunohistochemistry. Our results revealed upregulated expression of SIRT1 in all stages of gastric cancer compared with noncancerous gastric mucosa, suggesting that high SIRT1 levels are likely involved in establishing gastric neoplasticity. However, STAT3 and pSTAT3 levels remained low until the gastric mucosa reached the tumor stage. Moreover, co-ordinated high expression of SIRT1 and STAT3 predicted poor overall survival for advanced gastric cancer patients. In addition, through analysis of gastric cancer patients from the TCGA dataset, we identified SIRT2 as an independent prognostic factor in gastric cancer patients. We postulate that SIRT1 and STAT3 are potential early diagnostic and prognostic markers of gastric cancer. Our study also shows that SIRT1 acts a gatekeeper during gastric tumorigenesis.