Interplay among BRCA1, SIRT1, and Survivin during BRCA1-associated tumorigenesis

Druggable Molecular Networks in BRCA1/BRCA2-Mutated Breast Cancer

Mutations in the tumor suppressor genes BRCA1 and BRCA2 are associated with the triple-negative breast cancer phenotype, particularly aggressive and hard-to-treat tumors lacking estrogen, progesterone, and human epidermal growth factor receptor 2. This research aimed to understand the metabolic and genetic links behind BRCA1 and BRCA2 mutations and investigate their relationship with effective therapies. Using the Cytoscape software, two networks were generated through a bibliographic analysis of articles retrieved from the PubMed-NCBI database. We identified 98 genes deregulated by BRCA mutations, and 24 were modulated by therapies. In particular, BIRC5, SIRT1, MYC, EZH2, and CSN2 are influenced by BRCA1, while BCL2, BAX, and BRIP1 are influenced by BRCA2 mutation. Moreover, the study evaluated the efficacy of several promising therapies, targeting only BRCA1/BRCA2-mutated cells. In this context, CDDO-Imidazolide was shown to increase ROS levels and induce DNA damage. Similarly, resveratrol decreased the expression of the anti-apoptotic gene BIRC5 while it increased SIRT1 both in vitro and in vivo. Other specific drugs were found to induce apoptosis selectively in BRCA-mutated cells or block cell growth when the mutation occurs, i.e., 3-deazaneplanocin A, genistein or daidzein, and PARP inhibitors. Finally, over-representation analysis on the genes highlights ferroptosis and proteoglycan pathways as potential drug targets for more effective treatments.

NCAPD3 promotes diffuse large B-cell lymphoma progression through modulating SIRT1 expression in an H3K9 monomethylation-dependent manner

INTRODUCTION

Condensin, a family of structural maintenance of chromosome complexes, has been shown to regulate chromosome compaction and segregation during mitosis. NCAPD3, a HEAT-repeat subunit of condensin II, plays a dominant role in condensin-mediated chromosome dynamics but remains unexplored in lymphoma.

OBJECTIVES

The study aims to unravel the molecular function and mechanism of NCAPD3 in diffuse large B-cell lymphoma (DLBCL).

METHODS

The expression and clinical significance of NCAPD3 were assessed in public database and clinical specimens. Chromosome spreads, co-immunoprecipitation (co-IP), mass spectrometry (MS), and chromatin immunoprecipitation (ChIP) assays were conducted to untangle the role and mechanism of NCAPD3 in DLBCL.

RESULTS

NCAPD3 was highly expressed in DLBCL, correlated with poor prognosis. NCAPD3 deficiency impeded cell proliferation, induced apoptosis and increased the chemosensitivity. Instead, NCAPD3 overexpression facilitated cell proliferation. In vivo experiments further indicated targeting NCAPD3 suppressed tumor growth. Noteworthily, NCAPD3 deficiency disturbed the mitosis, triggering the formation of aneuploids. To reveal the function of NCAPD3 in DLBCL, chromosome spreads were conducted, presenting that chromosomes became compact upon NCAPD3 overexpression, instead, loose, twisted and lacking axial rigidity upon NCAPD3 absence. Meanwhile, the classical transcription-activated marker, H3K4 trimethylation, was found globally upregulated after NCAPD3 knockout, suggesting that NCAPD3 might participate in chromatin remodeling and transcription regulation. MS revealed NCAPD3 could interact with transcription factor, TFII I. Further co-IP and ChIP assays verified NCAPD3 could be anchored at the promoter of SIRT1 by TFII I and then supported the transcription of SIRT1 via recognizing H3K9 monomethylation (H3K9me1) on SIRT1 promoter. Function reversion assay verified the oncogenic role of NCAPD3 in DLBCL was partially mediated by SIRT1.

CONCLUSION

This study demonstrated that dysregulation of NCAPD3 could disturb chromosome compaction and segregation and regulate the transcription activity of SIRT1 in an H3K9me1-dependent manner, which provided novel insights into targeted strategy for DLBCL.

Molecular signaling and clinical implications in the human aging-cancer cycle

It is well documented that aging is associated with cancer, and likewise, cancer survivors display accelerated aging. As the number of aging individuals and cancer survivors continues to grow, it raises additional concerns across society. Therefore, unraveling the molecular mechanisms of aging in tissues is essential to developing effective therapies to fight the aging and cancer diseases in cancer survivors and cancer patients. Indeed, cellular senescence is a critical response, or a natural barrier to suppress the transition of normal cells into cancer cells, however, hypoxia which is physiologically required to maintain the stem cell niche, is increased by aging and inhibits senescence in tissues. Interestingly, oxygen restriction or hypoxia increases longevity and slows the aging process in humans, but hypoxia can also drive angiogenesis to facilitate cancer progression. In addition, cancer treatment is considered as one of the major reasons that drive cellular senescence, subsequently followed by accelerated aging. Several clinical trials have recently evaluated inhibitors to eliminate senescent cells. However, some mechanisms of aging typically can also retard cancer cell growth and progression, which might require careful strategy for better clinical outcomes. Here we describe the molecular regulation of aging and cancer in crosstalk with DNA damage and hypoxia signaling pathways in cancer patients and cancer survivors. We also update several therapeutic strategies that might be critical in reversing the cancer treatment-associated aging process.

A proteasome-dependent inhibition of SIRT-1 by the resveratrol analogue 4,4'-dihydroxy-trans-stilbene

Background and aim

Resveratrol (RSV), is a stilbene-based compound exerting wide biological properties. Its analogue 4,4'-dihydroxy-trans-stilbene (DHS) has shown improved bioavailability and antiproliferative activity in vitro and in vivo. One of the hypotheses on how resveratrol works is based on SIRT1 activation. Since their strict structural similarities, we have explored a potential interaction between DHS and SIRT1, in comparison with the parental molecule.

Experimental procedure

Timing of incubation and concentrations of DHS have been determined using MTT assay in normal human lung fibroblasts. Untreated, DHS- or RSV-treated cells were harvested and analysed by Western Blotting or RT-PCR, in order to evaluate SIRT1 levels/activity and expression, and by Cellular Thermal shift assay (CETSA) to check potential DHS or RSV-SIRT1 interaction. Transfection experiments have been performed with two SIRT1 mutants, based on the potential binding pockets identified by Molecular Docking analysis.

Results and conclusion

We unexpectedly found that DHS, but not RSV, exerted a time-dependent inhibitory effect on both SIRT1 protein levels and activity, the latter measured as p53 acetylation. At the mRNA level no significant changes were observed, whereas a proteasome-dependent mechanism was highlighted for the reduction of SIRT1 levels by DHS in experiments performed with the proteasome inhibitor MG132. Bioinformatics analysis suggested a higher affinity of RSV in binding all SIRT1 complexes compared to DHS, except comparable results for complex SIRT1-p53. Nevertheless, both CETSA and SIRT1 mutants transfected in cells did not confirm this interaction. In conclusion, DHS reduces SIRT1 protein level, thereby inhibiting its activity through a proteasome-mediated mechanism.

The Multifaceted Role of Endothelial Sirt1 in Vascular Aging: An Update

NAD+-dependent deacetylase sirtuin-1 (Sirt1) belongs to the sirtuins family, known to be longevity regulators, and exerts a key role in the prevention of vascular aging. By aging, the expression levels of Sirt1 decline with a severe impact on vascular function, such as the rise of endothelial dysfunction, which in turn promotes the development of cardiovascular diseases. In this context, the impact of Sirt1 activity in preventing endothelial senescence is particularly important. Given the key role of Sirt1 in counteracting endothelial senescence, great efforts have been made to deepen the knowledge about the intricate cross-talks and interactions of Sirt1 with other molecules, in order to set up possible strategies to boost Sirt1 activity to prevent or treat vascular aging. The aim of this review is to provide a proper background on the regulation and function of Sirt1 in the vascular endothelium and to discuss the recent advances regarding the therapeutic strategies of targeting Sirt1 to counteract vascular aging.

Targeting POLD1 to suppress the proliferation and migration of breast cancer MDA-MB-231 cell lines by downregulation of SIRT1

Background

The resistant and aggressive nature of triple-negative breast cancer (TNBC) renders it mostly incurable even following extensive multimodal treatment. Therefore, more studies are required to understand the underlying molecular mechanisms of its pathogenesis. SIRT1 is a class III histone deacetylase NAD + -dependent enzyme that is interlinked in tumor progression, apoptosis, metastasis, and other mechanisms of tumorigenesis, while DNA polymerase delta 1 (POLD1) functions as a gene coding for p125, which plays an important role in genome stability and DNA replication.

Objective

We aimed to investigate the downstream signaling pathway of EX-527, a potent and selective SIRT1 inhibitor, in MDA-MB-231 breast cancer cell lines, and the crosstalk between SIRT1 and POLD1, which is essential for the activities of polymerase δ.

Methods

The antiproliferative and apoptotic effects of EX-527 on MDA-MB-231 cells were assessed by MTT and annexin V/PI double staining assays. Migration and invasion activity of MDA-MB-231 cells were assessed by wound-healing scratch and transwell assays. Protein expressions were examined using Western Blot analysis.

Results

MDA-MB-231 cells treatment with IC50 values of 45.3 μM EX-527 significantly suppressed cell proliferation and induced apoptosis by down-regulating SIRT1. Also, it significantly repressed migration and invasion of MDA-MB-231 cells as evaluated by wound healing and transwell invasion assays. Western blot results showed that decreased expression of SIRT1 is positively correlated with expression of p53 along with down-regulating POLD1.

Conclusion

SIRT1 could have an oncogenic role in breast cancer development and progression via activating POLD1. These conclusions present new insights into the underlying mechanisms of TNBC.

Unlocking the Potential: Caloric Restriction, Caloric Restriction Mimetics, and Their Impact on Cancer Prevention and Treatment

Caloric restriction (CR) and its related alternatives have been shown to be the only interventions capable of extending lifespan and decreasing the risk of cancer, along with a reduction in burden in pre-clinical trials. Nevertheless, the results from clinical trials have not been as conclusive as the pre-clinical results. Recognizing the challenges associated with long-term fasting, the application of caloric restriction mimetics (CRMs), pharmacological agents that mimic the molecular effects of CR, to harness the potential benefits while overcoming the practical limitations of fasting has resulted in an interesting alternative. This review synthesizes the findings of diverse clinical trials evaluating the safety and efficacy of CR and CRMs. In dietary interventions, a fast-mimicking diet was the most tolerated to reduce tumoral growth markers and chemotherapy side effects. CRMs were well tolerated, and metformin and aspirin showed the most promising effect in reducing cancer risk in a selected group of patients. The application of CR and/or CRMs shows promising effects in anti-cancer therapy; however, there is a need for more evidence to safely include these interventions in standard-of-care therapies.

An update on existing therapeutic options and status of novel anti-metastatic agents in breast cancer: Elucidating the molecular mechanisms underlying the pleiotropic action of Withania somnifera (Indian ginseng) in breast cancer attenuation

Major significant advancements in pharmacology and drug technology have been made to heighten the impact of cancer therapies, improving the life expectancy of subjects diagnosed with malignancy. Statistically, 99% of breast cancers occur in women while 0.5-1% occur in men, the female gender being the strongest breast cancer risk factor. Despite several breakthroughs, breast cancer continues to have a worldwide impact and is one of the leading causes of mortality. Additionally, resistance to therapy is a crucial factor enabling cancer cell persistence and resurgence. As a result, the search and discovery of novel modulatory agents and effective therapies capable of controlling tumor progression and cancer cell proliferation is critical. Withania somnifera (L.) Dunal (WS), commonly known as Indian ginseng, has long been used traditionally for the treatment of several ailments in the Indian context. Recently, WS and its phytoconstituents have shown promising anti-breast cancer properties and, as such, can be employed as prophylactic as well as therapeutic adjuncts to the main line of breast cancer treatment. The present review is an attempt to explore and provide experimental evidences in support of the prophylactic and therapeutic potential of WS in breast cancer, along with a deeper insight into the multiple molecular mechanisms and novel targets through which it acts against breast and other hormonally-induced cancers viz. ovarian, uterine and cervical. This exploration might prove crucial in providing better understanding of breast cancer progression and metastasis and its use as an adjunct in improving disease prognosis and therapeutic outcome.

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

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

Survivin as a Therapeutic Target for the Treatment of Human Cancer

Survivin was initially identified as a member of the inhibitor apoptosis (IAP) protein family and has been shown to play a critical role in the regulation of apoptosis. More recent studies showed that survivin is a component of the chromosome passenger complex and acts as an essential mediator of mitotic progression. Other potential functions of survivin, such as mitochondrial function and autophagy, have also been proposed. Survivin has emerged as an attractive target for cancer therapy because its overexpression has been found in most human cancers and is frequently associated with chemotherapy resistance, recurrence, and poor survival rates in cancer patients. In this review, we discuss our current understanding of how survivin mediates various aspects of malignant transformation and drug resistance, as well as the efforts that have been made to develop therapeutics targeting survivin for the treatment of cancer.

Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents

The study of epigenetic translational modifications had drawn great interest for the last few decades. These processes play a vital role in many diseases and cancer is one of them. Histone acetyltransferase (HAT) and histone deacetylases (HDACs) are key enzymes involved in the acetylation and deacetylation of histones and ultimately in post-translational modifications. Cancer frequently exhibits epigenetic changes, particularly disruption in the expression and activity of HDACs. It includes the capacity to regulate proliferative signalling, circumvent growth inhibitors, escape cell death, enable replicative immortality, promote angiogenesis, stimulate invasion and metastasis, prevent immunological destruction, and genomic instability. The majority of tumours develop and spread as a result of HDAC dysregulation. As a result, HDAC inhibitors (HDACis) were developed, and they today stand as a very promising therapeutic approach. One of the most well-known and efficient therapies for practically all cancer types is chemotherapy. However, the efficiency and safety of treatment are constrained by higher toxicity. The same has been observed with the synthetic HDACi. Natural products, owing to many advantages over synthetic compounds for cancer treatment have always been a choice for therapy. Hence, naturally available molecules are of particular interest for HDAC inhibition and HDAC has drawn the attention of the research fraternity due to their potential to offer a diverse array of chemical structures and bioactive compounds. This diversity opens up new avenues for exploring less toxic HDAC inhibitors to reduce side effects associated with conventional synthetic inhibitors. The review presents comprehensive details on natural product HDACi, their mechanism of action and their biological effects. Moreover, this review provides a brief discussion on the structure activity relationship of selected natural HDAC inhibitors and their analogues which can guide future research to discover selective, more potent HDACi with minimal toxicity.

Decoupling NAD+ metabolic dependency in chondrosarcoma by targeting the SIRT1-HIF-2α axis

Chondrosarcomas represent the second most common primary bone malignancy. Despite the vulnerability of chondrosarcoma cells to nicotinamide adenine dinucleotide (NAD+) depletion, targeting the NAD+ synthesis pathway remains challenging due to broad implications in biological processes. Here, we establish SIRT1 as a central mediator reinforcing the dependency of chondrosarcoma cells on NAD+ metabolism via HIF-2α-mediated transcriptional reprogramming. SIRT1 knockdown abolishes aggressive phenotypes of chondrosarcomas in orthotopically transplanted tumors in mice. Chondrosarcoma cells thrive under glucose starvation by accumulating NAD+ and subsequently activating the SIRT1-HIF-2α axis. Decoupling this link via SIRT1 inhibition unleashes apoptosis and suppresses tumor progression in conjunction with chemotherapy. Unsupervised clustering analysis identifies a high-risk chondrosarcoma patient subgroup characterized by the upregulation of NAD+ biosynthesis genes. Finally, SIRT1 inhibition abolishes HIF-2α transcriptional activity and sensitizes chondrosarcoma cells to doxorubicin-induced cytotoxicity, irrespective of underlying pathways to accumulate intracellular NAD+. We provide system-level guidelines to develop therapeutic strategies for chondrosarcomas.

Effects of Functional and Nutraceutical Foods in the Context of the Mediterranean Diet in Patients Diagnosed with Breast Cancer

Several studies report that breast cancer survivors (BCS) tend to have a poor diet, as fruit, vegetable, and legume consumption is often reduced, resulting in a decreased intake of nutraceuticals. Moreover, weight gain has been commonly described among BCS during treatment, increasing recurrence rate and mortality. Improving lifestyle and nutrition after the diagnosis of BC may have important benefits on patients' general health and on specific clinical outcomes. The Mediterranean diet (MD), known for its multiple beneficial effects on health, can be considered a nutritional pool comprising several nutraceuticals: bioactive compounds and foods with anti-inflammatory and antioxidant effects. Recent scientific advances have led to the identification of nutraceuticals that could amplify the benefits of the MD and favorably influence gene expression in these patients. Nutraceuticals could have beneficial effects in the postdiagnostic phase of BC, including helping to mitigate the adverse effects of chemotherapy and radiotherapy. Moreover, the MD could be a valid and easy-to-follow option for managing excess weight. The aim of this narrative review is to evaluate the recent scientific literature on the possible beneficial effects of consuming functional and nutraceutical foods in the framework of MD in BCS.

Role of SIRT1 in Chemoresistant Leukemia

Leukemias of the AML, CML, and CLL types are the most common blood cancers worldwide, making them a major global public health problem. Furthermore, less than 24% of patients treated with conventional chemotherapy (low-risk patients) and 10-15% of patients ineligible for conventional chemotherapy (high-risk patients) survive five years. The low levels of survival are mainly due to toxicity and resistance to chemotherapy or other medication, the latter leading to relapse of the disease, which is the main obstacle to the treatment of leukemia. Drug resistance may include different molecular mechanisms, among which epigenetic regulators are involved. Silent information regulator 2 homolog 1 (SIRT1) is an epigenetic factor belonging to the sirtuin (SIRT) family known to regulate aspects of chromatin biology, genome stability, and metabolism, both in homeostasis processes and in different diseases, including cancer. The regulatory functions of SIRT1 in different biological processes and molecular pathways are dependent on the type and stage of the neoplasia; thus, it may act as both an oncogenic and tumor suppressor factor and may also participate in drug resistance. In this review, we explore the role of SIRT1 in drug-resistant leukemia and its potential as a therapeutic target.

Inhibition of Cancer Development by Natural Plant Polyphenols: Molecular Mechanisms

Malignant tumors remain one of the main sources of morbidity and mortality around the world. A chemotherapeutic approach to cancer treatment poses a multitude of challenges, primarily due to the low selectivity and genotoxicity of the majority of chemotherapeutic drugs currently used in the clinical practice, often leading to treatment-induced tumors formation. Highly selective antitumor drugs can largely resolve this issue, but their high selectivity leads to significant drawbacks due to the intrinsic tumor heterogeneity. In contrast, plant polyphenols can simultaneously affect many processes that are involved in the acquiring and maintaining of hallmark properties of malignant cells, and their toxic dose is typically much higher than the therapeutic one. In the present work we describe the mechanisms of the action of polyphenols on cancer cells, including their effects on genetic and epigenetic instability, tumor-promoting inflammation, and altered microbiota.

The Role of NAD+, SIRTs Interactions in Stimulating and Counteracting Carcinogenesis

The World Health Organization has identified oncological diseases as one of the most serious health concerns of the current century. Current research on oncogenesis is focused on the molecular mechanisms of energy-biochemical reprogramming in cancer cell metabolism, including processes contributing to the Warburg effect and the pro-oncogenic and anti-oncogenic roles of sirtuins (SIRTs) and poly-(ADP-ribose) polymerases (PARPs). However, a clear understanding of the interaction between NAD⁺, SIRTs in cancer development, as well as their effects on carcinogenesis, has not been established, and literature data vary greatly. This work aims to provide a summary and structure of the available information on NAD⁺, SIRTs interactions in both stimulating and countering carcinogenesis, and to discuss potential approaches for pharmacological modulation of these interactions to achieve an anticancer effect.

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

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

Narrow Leafed Lupin (Lupinus angustifolius L.) β-Conglutin Seed Proteins as a New Natural Cytotoxic Agents against Breast Cancer Cells

Breast cancer (BC) is the most widespread tumor in women and the second type of most common cancer worldwide. Despite all the technical and medical advances in existing therapies, between 30 and 50% of patients with BC will develop metastasis, which contributes to the failure of existing treatments. This situation urges the need to find more effective prevention and treatment strategies like the use of plant-based nutraceutical compounds. In this context, we purified three Narrow Leafed Lupin (NLL) β-conglutins isoforms using affinity-chromatography and evaluated their effectiveness in terms of viability, proliferation, apoptosis, stemness properties, and mechanism of action on both BC cell lines and a healthy one. NLL β-conglutins proteins have very promising effects at the molecular level on BC cells at very low concentrations, emerging as a potential natural cytotoxic agent and preserving the viability of healthy cells. These proteins could act through a dual mechanism involving tumorigenic and stemness-related genes such as SIRT1 and FoxO1, depending on the state of p53. More studies must be carried out to completely understand the underlying mechanisms of action of these nutraceutical compounds in BC in vitro and in vivo, and their potential use for the inhibition of other cancer cell types.

Sirtuins (SIRTs) As a Novel Target in Gastric Cancer

Gastric cancer is a major health burden worldwide. Among all neoplasms, gastric cancer is the fifth most common and the third most deadly type of cancer. It is known that sirtuins (SIRTs), are NAD⁺-dependent histone deacetylases regulating important metabolic pathways. High expression of SIRTs in the human body can regulate metabolic processes; they prevent inflammation but also resist cell death and aging processes. The seven members of this family enzymes can also play a fundamental role in process of carcinogenesis by influencing cell viability, apoptosis and metastasis. This review collects and discusses the role of all seven sirtuins (SIRT1-SIRT7) in the pathogenesis of gastric cancer (GC).

IGF2BP2 promotes cancer progression by degrading the RNA transcript encoding a v-ATPase subunit

IGF2BP2 binds to a number of RNA transcripts and has been suggested to function as a tumor promoter, although little is known regarding the mechanisms that regulate its roles in RNA metabolism. Here we demonstrate that IGF2BP2 binds to the 3' untranslated region of the transcript encoding ATP6V1A, a catalytic subunit of the vacuolar ATPase (v-ATPase), and serves as a substrate for the NAD⁺-dependent deacetylase SIRT1, which regulates how IGF2BP2 affects the stability of the ATP6V1A transcript. When sufficient levels of SIRT1 are expressed, it catalyzes the deacetylation of IGF2BP2, which can bind to the ATP6V1A transcript but does not mediate its degradation. However, when SIRT1 expression is low, the acetylated form of IGF2BP2 accumulates, and upon binding to the ATP6V1A transcript recruits the XRN2 nuclease, which catalyzes transcript degradation. Thus, the stability of the ATP6V1A transcript is significantly compromised in breast cancer cells when SIRT1 expression is low or knocked-down. This leads to a reduction in the expression of functional v-ATPase complexes in cancer cells and to an impairment in their lysosomal activity, resulting in the production of a cellular secretome consisting of increased numbers of exosomes enriched in ubiquitinated protein cargo and soluble hydrolases, including cathepsins, that together combine to promote tumor cell survival and invasiveness. These findings describe a previously unrecognized role for IGF2BP2 in mediating the degradation of a messenger RNA transcript essential for lysosomal function and highlight how its sirtuin-regulated acetylation state can have significant biological and disease consequences.

Epigenetics and environment in breast cancer: New paradigms for anti-cancer therapies

Breast cancer remains the most frequently diagnosed cancer in women worldwide. Delayed presentation of the disease, late stage at diagnosis, limited therapeutic options, metastasis, and relapse are the major factors contributing to breast cancer mortality. The development and progression of breast cancer is a complex and multi-step process that incorporates an accumulation of several genetic and epigenetic alterations. External environmental factors and internal cellular microenvironmental cues influence the occurrence of these alterations that drives tumorigenesis. Here, we discuss state-of-the-art information on the epigenetics of breast cancer and how environmental risk factors orchestrate major epigenetic events, emphasizing the necessity for a multidisciplinary approach toward a better understanding of the gene-environment interactions implicated in breast cancer. Since epigenetic modifications are reversible and are susceptible to extrinsic and intrinsic stimuli, they offer potential avenues that can be targeted for designing robust breast cancer therapies.

Cellular reprogramming, chemoresistance, and dietary interventions in breast cancer

Breast cancer (BC) diagnosis has been associated with significant risk factors, including family history, late menopause, obesity, poor eating habits, and alcoholism. Despite the advances in the last decades regarding cancer treatment, some obstacles still hinder the effectiveness of therapy. For example, chemotherapy resistance is common in locally advanced or metastatic cancer, reducing treatment options and contributing to mortality. In this review, we provide an overview of BC metabolic changes, including the impact of restrictive diets associated with chemoresistance, the therapeutic potential of the diet on tumor progression, pathways related to metabolic health in oncology, and perspectives on the future in the area of oncological nutrition.

Nucleolar protein NOC4L inhibits tumorigenesis and progression by attenuating SIRT1-mediated p53 deacetylation

SIRT1 is an NAD⁺-dependent deacetylase and plays an important role in the deacetylation of both histone and non-histone proteins. Many studies revealed that SIRT1 is upregulated in a variety of tumors and tightly associated with tumorigenesis and cancer progression, but the detailed underlying mechanism of the biological processes remains unclarified. In the present study, we found a nucleolar protein NOC4L, human ortholog of yeast Noc4p, which is essential for the nuclear export of the ribosomal 40S subunit and could bind to SIRT1 to inhibit SIRT1 mediated deacetylation of p53. NOC4L interacts with SIRT1 in variety of cells under nucleolar stress and directly interacts with SIRT1 in vitro. Furthermore, we determined the C-terminal of NOC4L and the catalytic domain of SIRT1 were required for their interaction. Overexpression of NOC4L did not change the protein levels of SIRT1 or p53, but increased the acetylation of p53 and promoted cell apoptosis. Additionally, NOC4L inhibited tumor cell proliferation in a p53-dependent manner and restrained tumor growth in a nude mice xenograft model. Clinically, colorectal cancer patients with the high expression of NOC4L had a better prognosis as TP53 was normally expressed, but no significant difference was observed in survival with mutant TP53. Taken together, our results identified a novel SIRT1 regulatory protein and broaden our understanding of the molecular mechanism of how nucleolar protein NOC4L regulates p53 under nucleolar stress. This research provides an insight into tumorigenesis and cell self-protection in the early stage of DNA damage.

Role of sirtuins in esophageal cancer: Current status and future prospects

Esophageal cancer (EC) is a malignant cancer that still has a poor prognosis, although its prognosis has been improving with the development of multidisciplinary treatment modalities such as surgery, chemotherapy and radiotherapy. Therefore, identifying specific molecular markers that can be served as biomarkers for the prognosis and treatment response of EC is highly desirable to aid in the personalization and improvement of the precision of medical treatment. Sirtuins are a family of nicotinamide adenine dinucleotide (NAD+)-dependent proteins consisting of seven members (SIRT1-7). These proteins have been reported to be involved in the regulation of a variety of biological functions including apoptosis, metabolism, stress response, senescence, differentiation and cell cycle progression. Given the variety of functions of sirtuins, they are speculated to be associated in some manner with cancer progression. However, while the role of sirtuins in cancer progression has been investigated over the past few years, their precise role remains difficult to characterize, as they have both cancer-promoting and cancer-suppressing properties, depending on the type of cancer. These conflicting characteristics make research into the nature of sirtuins all the more fascinating. However, the role of sirtuins in EC remains unclear due to the limited number of reports concerning sirtuins in EC. We herein review the current findings and future prospects of sirtuins in EC.

Advances and challenges in cancer treatment and nutraceutical prevention: the possible role of dietary phenols in BRCA regulation

Over the years, the attention towards the role of phytochemicals in dietary natural products in reducing the risk of developing cancer is rising. Cancer is the second primary cause of mortality worldwide. The current therapeutic options for cancer treatment are surgical excision, immunotherapy, chemotherapy, and radiotherapy. Unfortunately, in case of metastases or chemoresistance, the treatment options become very limited. Despite the advances in medical and pharmaceutical sciences, the impact of available treatments on survival is not satisfactory. Recently, natural products are a great deal of interest as potential anti-cancer agents. Among them, phenolic compounds have gained a great deal of interest, thanks to their anti-cancer activity. The present review focuses on the suppression of cancer by targeting BRCA gene expression using dietary polyphenols, as well as the clinical aspects of polyphenolic agents in cancer therapy. They regulate specific key processes involved in cancer progression and modulate the expression of oncogenic proteins, like p27, p21, and p53, which may lead to apoptosis, cell cycle arrest, inhibition of cell proliferation, and, consequently, cancer suppression. Thus, one of the mechanisms underlying the anti-cancer activity of phenolics involves the regulation of tumor suppressor genes. Among them, the BRCA genes, with the two forms (BRCA-1 and BRCA-2), play a pivotal role in cancer protection and prevention. BRCA germline mutations are associated with an increased risk of developing several types of cancers, including ovarian, breast, and prostate cancers. BRCA genes also play a key role in the sensitivity and response of cancer cells to specific pharmacological treatments. As the importance of BRCA-1 and BRCA-2 in reducing cancer invasiveness, repairing DNA damages, oncosoppression, and cell cycle checkpoint, their regulation by natural molecules has been examined.

Celastrol and Resveratrol Modulate SIRT Genes Expression and Exert Anticancer Activity in Colon Cancer Cells and Cancer Stem-like Cells

Simple Summary

The recovery rate in patients with metastatic colorectal cancer (CRC) remains low and declines with successive lines of treatment. This phenomenon is caused by the development of drug resistance and the presence of colorectal cancer stem cells (CSCs). Phytochemicals, like -celastrol and resveratrol, are very promising for colon cancer therapy, owing to their low or no toxicity and their pleiotropic activity, enabling them to interact with various biological targets. In the present study, the potential anticancer mechanisms of both compounds against metastatic colon cancer cells and the capacity to eradicate CSCs were investigated.

Abstract

Metastatic colorectal cancer (CRC) remains a hard-to-cure neoplasm worldwide. Its curability declines with successive lines of treatment due to the development of various cancer resistance mechanisms and the presence of colorectal cancer stem cells (CSCs). Celastrol and resveratrol are very promising phytochemicals for colon cancer therapy, owing to their pleiotropic activity that enables them to interact with various biological targets. In the present study, the anticancer activities of both compounds were investigated in metastatic colon cancer cells (LoVo cells) and cancer stem-like cells (LoVo/DX). We showed that celastrol is a very potent anti-tumor compound against metastatic colon cancer, capable of attenuating CSC-like cells at the molecular and cellular levels. In contrast, resveratrol has a much greater effect on colon cancer cells that are expressing standard sensitivity to anticancer drugs, than on CSC-like cells. In addition, both polyphenols have different influences on the expression of SIRT genes, which seems to be at least partly related to their anti-tumor activity.

SIRT1 Expression Is a Promising Prognostic Biomarker in Esophageal Squamous Cell Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND/AIM

Several articles have assessed the prognostic significance of the expression of sirtuin 1 (SIRT1) in esophageal squamous cell carcinoma (ESCC). However, evidence in this field is insufficient. Thus, we conducted a meta-analysis to investigate the prognostic and clinical impact of SIRT1 expression in ESCC.

MATERIALS AND METHODS

We searched the PubMed, Cochrane Library, and Web of Science databases for articles on the expression of SIRT1 and clinicopathological features in patients with ESCC. A meta-analysis was conducted.

RESULTS

Four studies with 429 patients were included. The meta-analysis revealed a significant relationship between the high expression of SIRT1 and higher T-stage (odds ratio=2.39. 95% confidence interval=1.12-5.13, p=0.02), more advanced TNM stage (odds ratio=2.35. 95% confidence interval=1.20-4.60, p=0.01), and a poor overall survival (hazard ratio=1.90, 95% confidence interval=1.45-2.47, p<0.00001).

CONCLUSION

SIRT1 expression may be a promising prognostic biomarker for patients with ESCC.

The Role of Epigenetic Modifications in Human Cancers and the Use of Natural Compounds as Epidrugs: Mechanistic Pathways and Pharmacodynamic Actions

Cancer is a complex disease resulting from the genetic and epigenetic disruption of normal cells. The mechanistic understanding of the pathways involved in tumor transformation has implicated a priori predominance of epigenetic perturbations and a posteriori genetic instability. In this work, we aimed to explain the mechanistic involvement of epigenetic pathways in the cancer process, as well as the abilities of natural bioactive compounds isolated from medicinal plants (flavonoids, phenolic acids, stilbenes, and ketones) to specifically target the epigenome of tumor cells. The molecular events leading to transformation, angiogenesis, and dissemination are often complex, stochastic, and take turns. On the other hand, the decisive advances in genomics, epigenomics, transcriptomics, and proteomics have allowed, in recent years, for the mechanistic decryption of the molecular pathways of the cancerization process. This could explain the possibility of specifically targeting this or that mechanism leading to cancerization. With the plasticity and flexibility of epigenetic modifications, some studies have started the pharmacological screening of natural substances against different epigenetic pathways (DNA methylation, histone acetylation, histone methylation, and chromatin remodeling) to restore the cellular memory lost during tumor transformation. These substances can inhibit DNMTs, modify chromatin remodeling, and adjust histone modifications in favor of pre-established cell identity by the differentiation program. Epidrugs are molecules that target the epigenome program and can therefore restore cell memory in cancerous diseases. Natural products isolated from medicinal plants such as flavonoids and phenolic acids have shown their ability to exhibit several actions on epigenetic modifiers, such as the inhibition of DNMT, HMT, and HAT. The mechanisms of these substances are specific and pleiotropic and can sometimes be stochastic, and their use as anticancer epidrugs is currently a remarkable avenue in the fight against human cancers.

G-Quadruplex Matters in Tissue-Specific Tumorigenesis by BRCA1 Deficiency

How and why distinct genetic alterations, such as BRCA1 mutation, promote tumorigenesis in certain tissues, but not others, remain an important issue in cancer research. The underlying mechanisms may reveal tissue-specific therapeutic vulnerabilities. Although the roles of BRCA1, such as DNA damage repair and stalled fork stabilization, obviously contribute to tumor suppression, these ubiquitously important functions cannot explain tissue-specific tumorigenesis by BRCA1 mutations. Recent advances in our understanding of the cancer genome and fundamental cellular processes on DNA, such as transcription and DNA replication, have provided new insights regarding BRCA1-associated tumorigenesis, suggesting that G-quadruplex (G4) plays a critical role. In this review, we summarize the importance of G4 structures in mutagenesis of the cancer genome and cell type-specific gene regulation, and discuss a recently revealed molecular mechanism of G4/base excision repair (BER)-mediated transcriptional activation. The latter adequately explains the correlation between the accumulation of unresolved transcriptional regulatory G4s and multi-level genomic alterations observed in BRCA1-associated tumors. In summary, tissue-specific tumorigenesis by BRCA1 deficiency can be explained by cell type-specific levels of transcriptional regulatory G4s and the role of BRCA1 in resolving it. This mechanism would provide an integrated understanding of the initiation and development of BRCA1-associated tumors.

SYT8 promotes pancreatic cancer progression via the TNNI2/ERRα/SIRT1 signaling pathway

Pancreatic cancer is a highly lethal malignancy due to failures of early detection and high metastasis in patients. While certain genetic mutations in tumors are associated with severity, the molecular mechanisms responsible for cancer progression are still poorly understood. Synaptotagmin-8 (SYT8) is a membrane protein that regulates hormone secretion and neurotransmission, and its expression is positively regulated by the promoter of the insulin gene in pancreatic islet cells. In this study, we identified a previously unknown role of SYT8 in altering tumor characteristics in pancreatic cancer. SYT8 levels were upregulated in patient tumors and contributed towards increased cell proliferation, migration, and invasion in vitro and in vivo. Increased SYT8 expression also promoted tumor metastasis in an in vivo tumor metastasis model. Furthermore, we showed that SYT8-mediated increase in tumorigenicity was regulated by SIRT1, a protein deacetylase previously known to alter cell metabolism in pancreatic lesions. SIRT1 expression was altered by orphan nuclear receptor ERRα and troponin-1 (TNNI2), resulting in cell proliferation and migration in an SYT8-dependent manner. Together, we identified SYT8 to be a central regulator of tumor progression involving signaling via the SIRT1, ERRα, and TNNI2 axis. This knowledge may provide the basis for the development of therapeutic strategies to restrict tumor metastasis in pancreatic cancer.

Inhibition of Knee Osteoarthritis Progression in Mice by Administering SRT2014, an Activator of Silent Information Regulator 2 Ortholog 1

OBJECTIVE

Previous findings suggest that silent information regulator 2 ortholog 1 (SIRT1) plays essential roles in chondrocytes and prevents osteoarthritis (OA) development. The purpose of this study was to investigate the effects of intraperitoneal (i.p.) and intra-articular (i.a.) administration of the SIRT1 activator SRT2104, which has been approved for use in humans.

DESIGN

OA was induced by destabilizing the medial meniscus in the knee joint of 12-week-old CL57BL/6J mice. The mice were divided into 3 groups, that is, the control group, SRT2104 i.p.-injection group, and SRT2104 i.a.-injection group. Tissues were harvested at 4, 8, 12, and 16 weeks postsurgery. OA progression was evaluated using the Osteoarthritis Research Society International (OARSI) score. The production of OA-related proteins in cartilage and synovium was examined by immunohistochemistry.

RESULTS

OARSI scores in the control group were significantly higher at 8 and 12 weeks compared with other 2 groups. Immunohistochemical analysis showed that Sirt1 and type-2 collagen significantly increased, whereas MMP-13, ADAMTS-5, IL-1β, IL-6, cleaved caspase 3, PARP p85, acetylated NF-κB p65, and iNOS decreased significantly in cartilage tissues from the i.p. and i.a, SRT2104 groups. In the synovium, more iNOS-positive M1-like macrophages were observed in the control group than in the i.p. and i.a, SRT2104 groups, whereas more CD206-positive M2-like macrophages were detected in the i.p. and i.a. SRT2104 groups.

CONCLUSIONS

Both i.p. and i.a. SRT2104 injection reduced OA progression in the mouse OA model, suggesting that SRT2104 can serve as a new treatment for OA.

Sirtuin inhibition is synthetic lethal with BRCA1 or BRCA2 deficiency

PARP enzymes utilise NAD+ as a co-substrate for their enzymatic activity. Inhibition of PARP1 is synthetic lethal with defects in either BRCA1 or BRCA2. In order to assess whether other genes implicated in NAD+ metabolism were synthetic lethal with BRCA1 or BRCA2 gene defects, we carried out a genetic screen, which identified a synthetic lethality between BRCA1 and genetic inhibition of either of two sirtuin (SIRT) enzymes, SIRT1 or SIRT6. This synthetic lethal interaction was replicated using small-molecule SIRT inhibitors and was associated with replication stress and increased cellular PARylation, in contrast to the decreased PARylation associated with BRCA-gene/PARP inhibitor synthetic lethality. SIRT/BRCA1 synthetic lethality was reversed by genetic ablation of either PARP1 or the histone PARylation factor-coding gene HPF1, implicating PARP1/HPF1-mediated serine ADP-ribosylation as part of the mechanistic basis of this synthetic lethal effect. These observations suggest that PARP1/HPF1-mediated serine ADP-ribosylation, when driven by SIRT inhibition, can inadvertently inhibit the growth of BRCA-gene mutant cells.

Targeting Histone Modifications in Breast Cancer: A Precise Weapon on the Way

Histone modifications (HMs) contribute to maintaining genomic stability, transcription, DNA repair, and modulating chromatin in cancer cells. Furthermore, HMs are dynamic and reversible processes that involve interactions between numerous enzymes and molecular components. Aberrant HMs are strongly associated with tumorigenesis and progression of breast cancer (BC), although the specific mechanisms are not completely understood. Moreover, there is no comprehensive overview of abnormal HMs in BC, and BC therapies that target HMs are still in their infancy. Therefore, this review summarizes the existing evidence regarding HMs that are involved in BC and the potential mechanisms that are related to aberrant HMs. Moreover, this review examines the currently available agents and approved drugs that have been tested in pre-clinical and clinical studies to evaluate their effects on HMs. Finally, this review covers the barriers to the clinical application of therapies that target HMs, and possible strategies that could help overcome these barriers and accelerate the use of these therapies to cure patients.

Sirt1 deficiency upregulates glutathione metabolism to prevent hepatocellular carcinoma initiation in mice

Sirtuin-1 (SIRT1) is involved in various metabolic pathways, including fatty acid synthesis and gluconeogenesis in the liver. However, its role in initiation and progression of liver cancer remains unclear. Studying Sirt1 liver-specific knockout (LKO) mice in combination with diethylnitrosamine (DEN) treatment, we demonstrated that loss of Sirt1 rendered mice resistant to DEN-induced hepatocellular carcinoma (HCC) development. RNA-seq revealed that livers from LKO mice exhibited an enrichment in glutathione metabolism eight months after DEN challenge. Sirt1 deficiency elevated the expression of glutathione-s-transferase family genes by increasing the level of Nrf2, a key regulator of glutathione metabolism. Hence, LKO livers displayed a reductive environment with an increased ratio of GSH to GSSG and an elevated GSH level. Furthermore, using CRISPR knockout techniques, we confirmed that the impairment of HCC formation in LKO mice is mainly dependent on NRF2 signaling. Meanwhile, HCC induced by DEN could be blocked by the administration of N-acetyl cysteine (NAC) when administered one month after DEN challenge. However, NAC treatment starting five months after DEN injection was not able to prevent tumor development. In conclusion, our findings indicate that a reductive environment orchestrated by glutathione metabolism at an early stage can prevent the initiation of HCC.

Expression Patterns of TOP2A and SIRT1 Are Predictive of Survival in Patients with High-Risk Soft Tissue Sarcomas Treated with a Neoadjuvant Anthracycline-Based Chemotherapy

Molecular predictors of response to chemotherapy and survival have not been put into clinical practice in high-risk soft tissue sarcomas (HR-STS) by now. The expression of TOP2A and SIRT1 has implications for the mechanism of action of doxorubicin, which is the backbone of chemotherapy in HR-STS. Pre-treatment samples of 167 patients with HR-STS were collected. Protein expression levels of TOP2A and SIRT1 were evaluated with tissue microarrays and immunohistochemistry and correlated with clinicopathological parameters, including overall survival (OS). The expression of TOP2A and SIRT1 was seen in 47% and 60% of patients with HR-STS, respectively. TOP2A expression was associated with higher tumor grading and shorter 5-year OS. The expression of SIRT1 was correlated with a better 5- and 10-year OS. The combination of high SIRT1 and low TOP2A ("Top survivors") significantly predicted a better OS compared to other biomarker combinations. A multivariate analysis confirmed the expression of SIRT1 and the "Top survivor" biomarker combination as independent predictive factors of OS. This is the first study to associate SIRT1 overexpression with a statistically significant prolongation of OS in HR-STS. Both individual markers and their combination can be used as predictive indicators for HR-STS patients scheduled for neoadjuvant anthracycline-based chemotherapy.

Hesperidin and Chlorogenic Acid Synergistically Inhibit the Growth of Breast Cancer Cells via Estrogen Receptor/Mitochondrial Pathway

Breast cancer is the most common cancer in women worldwide. Hesperidin (Hes) and chlorogenic acid (CA) are traditional medicinal molecules that abundantly exist in natural plants or foods. These compounds have been shown to prevent and suppress various cancers and therefore can be utilized as adjunctive therapies to aid cancer treatment. Here, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays show a greater synergistic inhibitory effect on the growth of breast cancer cells, MCF-7, but not normal breast cells, MCF-10A, than hesperidin or chlorogenic acid alone. We present the possible molecular signaling pathways in MCF-7 cells with or without herbal molecule treatments via proteomic approaches. The data were further analyzed by Ingenuity Pathway Analysis (IPA) and confirmed by quantifying mRNA associated with the estrogen-receptor signaling pathway and mitochondrial functions. We demonstrated that the expression of CYC1, TFAM, ATP5PB, mtATP6, mtDNA, and NRF-1 were decreased upon 12 h treatment, and subsequent ATP production was also significantly decreased at 24 h. These results identified a synergistic effect induced by combinational treatment with hesperidin and chlorogenic acid, which can regulate mitochondria and ATP production through the estrogen receptor pathway in MCF-7 cells. However, none of the treatments induced the generation of reactive oxygen species (ROS), suggesting that ROS likely plays no role in the observed pharmacological activities. Overall, our study sheds light on the adequacy of hesperidin and chlorogenic acid to serve as an adjunctive therapy when co-administrated with chemotherapy drugs in breast cancer patients.

Plasma Metabolome Signature Indicative of BRCA1 Germline Status Independent of Cancer Incidence

Individuals carrying a pathogenic germline variant in the breast cancer predisposition gene BRCA1 (gBRCA1+) are prone to developing breast cancer. Apart from its well-known role in DNA repair, BRCA1 has been shown to powerfully impact cellular metabolism. While, in general, metabolic reprogramming was named a hallmark of cancer, disrupted metabolism has also been suggested to drive cancer cell evolution and malignant transformation by critically altering microenvironmental tissue integrity. Systemic metabolic effects induced by germline variants in cancer predisposition genes have been demonstrated before. Whether or not systemic metabolic alterations exist in gBRCA1+ individuals independent of cancer incidence has not been investigated yet. We therefore profiled the plasma metabolome of 72 gBRCA1+ women and 72 age-matched female controls, none of whom (carriers and non-carriers) had a prior cancer diagnosis and all of whom were cancer-free during the follow-up period. We detected one single metabolite, pyruvate, and two metabolite ratios involving pyruvate, lactate, and a metabolite of yet unknown structure, significantly altered between the two cohorts. A machine learning signature of metabolite ratios was able to correctly distinguish between gBRCA1+ and controls in ~82%. The results of this study point to innate systemic metabolic differences in gBRCA1+ women independent of cancer incidence and raise the question as to whether or not constitutional alterations in energy metabolism may be involved in the etiology of BRCA1-associated breast cancer.

Natural products in the reprogramming of cancer epigenetics

Owing to the technological advancements, including next generation sequencing, the significance of deregulated epigenetic mechanisms in cancer initiation, progression and treatment has become evident. The accumulating knowledge relating to the epigenetic markers viz. DNA methylation, Histone modifications and non-coding RNAs make them one of the most interesting candidates for developing anti-cancer therapies. The reversibility of deregulated epigenetic mechanisms through environmental and dietary factors opens numerous avenues in the field of chemoprevention and drug development. Recent studies have proven that plant-derived natural products encompass a great potential in targeting epigenetic signatures in cancer and numerous natural products are being explored for their possibility to be considered as "epi-drug". This review intends to highlight the major aberrant epigenetic mechanisms and summarizes the essential functions of natural products like Resveratrol, Quercetin, Genistein, EGCG, Curcumin, Sulforaphane, Apigenin, Parthenolide and Berberine in modulating these aberrations. This knowledge along with the challenges and limitations in this field has potential and wider implications in developing novel and successful therapeutic strategies. The increased focus in the area will possibly provide a better understanding for the development of dietary supplements and/or drugs either alone or in combination. The interaction of epigenetics with different hallmarks of cancer and how natural products can be utilized to target them will also be interesting in the future therapeutic approaches.

Bilirubin as a metabolic hormone: the physiological relevance of low levels

Recent research on bilirubin, a historically well-known waste product of heme catabolism, suggests an entirely new function as a metabolic hormone that drives gene transcription by nuclear receptors. Studies are now revealing that low plasma bilirubin levels, defined as "hypobilirubinemia," are a possible new pathology analogous to the other end of the spectrum of extreme hyperbilirubinemia seen in patients with jaundice and liver dysfunction. Hypobilirubinemia is most commonly seen in patients with metabolic dysfunction, which may lead to cardiovascular complications and possibly stroke. We address the clinical significance of low bilirubin levels. A better understanding of bilirubin's hormonal function may explain why hypobilirubinemia might be deleterious. We present mechanisms by which bilirubin may be protective at mildly elevated levels and research directions that could generate treatment possibilities for patients with hypobilirubinemia, such as targeting of pathways that regulate its production or turnover or the newly designed bilirubin nanoparticles. Our review here calls for a shift in the perspective of an old molecule that could benefit millions of patients with hypobilirubinemia.

Preclinical evaluation of radiation therapy of BRCA1-associated mammary tumors using a mouse model

Although germline mutations in BRCA1 highly predispose women towards breast and ovarian cancer, few substantial improvements in preventing or treating such cancers have been made. Importantly, BRCA1 function is closely associated with DNA damage repair, which is required for genetic stability. Here, we examined the efficacy of radiotherapy, assessing the accumulation of genetic instabilities, in the treatment of BRCA1-associated breast cancer using a Brca1-mutant mouse model. Treatment of Brca1-mutant tumor-engrafted mice with X-rays reduced tumor progression by 27.9% compared with untreated controls. A correlation analysis of irradiation responses and biomarker profiles in tumors at baseline identified differences between responders and non-responders at the protein level (pERα, pCHK2, p53, and EpCAM) and at the SOX2 target expression level. We further demonstrated that combined treatment of Brca1-mutant mammary tumors with irradiation and AZD2281, which inhibits PARP, significantly reduced tumor progression and extended survival. Our findings enhance the understanding of DNA damage and biomarker responses in BRCA1-associated mammary tumors and provide preclinical evidence that radiotherapy with synthetic DNA damage is a potential strategy for the therapeutic management of BRCA1-associated breast cancer.

Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism

Simple Summary

The prevention and treatment of cancer is an ongoing medical challenge. In the context of personalized medicine, the well-studied polyphenol resveratrol could complement classical tumor therapy. It may affect key processes such as inflammation, angiogenesis, proliferation, metastasis, glucose metabolism, and apoptosis in various cancers because resveratrol acts as a multi-targeting agent by modulating multiple signal transduction pathways. This review article focuses on resveratrol’s ability to modify tumor glucose metabolism and its associated therapeutic capacity. Resveratrol reduces glucose uptake and glycolysis by affecting Glut1, PFK1, HIF-1α, ROS, PDH, and the CamKKB/AMPK pathway. It also inhibits cell growth, invasion, and proliferation by targeting NF-kB, Sirt1, Sirt3, LDH, PI-3K, mTOR, PKM2, R5P, G6PD, TKT, talin, and PGAM. In addition, resveratrol induces apoptosis by targeting integrin, p53, LDH, and FAK. In conclusion, resveratrol has many potentials to intervene in tumor processes if bioavailability can be increased and this natural compound can be used selectively.

Abstract

Tumor cells develop several metabolic reprogramming strategies, such as increased glucose uptake and utilization via aerobic glycolysis and fermentation of glucose to lactate; these lead to a low pH environment in which the cancer cells thrive and evade apoptosis. These characteristics of tumor cells are known as the Warburg effect. Adaptive metabolic alterations in cancer cells can be attributed to mutations in key metabolic enzymes and transcription factors. The features of the Warburg phenotype may serve as promising markers for the early detection and treatment of tumors. Besides, the glycolytic process of tumors is reversible and could represent a therapeutic target. So-called mono-target therapies are often unsafe and ineffective, and have a high prevalence of recurrence. Their success is hindered by the ability of tumor cells to simultaneously develop multiple chemoresistance pathways. Therefore, agents that modify several cellular targets, such as energy restriction to target tumor cells specifically, have therapeutic potential. Resveratrol, a natural active polyphenol found in grapes and red wine and used in many traditional medicines, is known for its ability to target multiple components of signaling pathways in tumors, leading to the suppression of cell proliferation, activation of apoptosis, and regression in tumor growth. Here, we describe current knowledge on the various mechanisms by which resveratrol modulates glucose metabolism, its potential as an imitator of caloric restriction, and its therapeutic capacity in tumors.

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.

Verticillin A Causes Apoptosis and Reduces Tumor Burden in High-Grade Serous Ovarian Cancer by Inducing DNA Damage

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy in women worldwide and the fifth most common cause of cancer-related deaths among U.S. women. New therapies are needed to treat HGSOC, particularly because most patients develop resistance to current first-line therapies. Many natural product and fungal metabolites exhibit anticancer activity and represent an untapped reservoir of potential new agents with unique mechanism(s) of action. Verticillin A, an epipolythiodioxopiperazine alkaloid, is one such compound, and our recent advances in fermentation and isolation are now enabling evaluation of its anticancer activity. Verticillin A demonstrated cytotoxicity in HGSOC cell lines in a dose-dependent manner with a low nmol/L IC₅₀ Furthermore, treatment with verticillin A induced DNA damage and caused apoptosis in HGSOC cell lines OVCAR4 and OVCAR8. RNA-Seq analysis of verticillin A-treated OVCAR8 cells revealed an enrichment of transcripts in the apoptosis signaling and the oxidative stress response pathways. Mass spectrometry histone profiling confirmed reports that verticillin A caused epigenetic modifications with global changes in histone methylation and acetylation marks. To facilitate in vivo delivery of verticillin A and to monitor its ability to reduce HGSOC tumor burden, verticillin A was encapsulated into an expansile nanoparticle (verticillin A-eNP) delivery system. In an in vivo human ovarian cancer xenograft model, verticillin A-eNPs decreased tumor growth and exhibited reduced liver toxicity compared with verticillin A administered alone. This study confirmed that verticillin A has therapeutic potential for treatment of HGSOC and that encapsulation into expansile nanoparticles reduced liver toxicity.

Modulation of antioxidant enzymes, SIRT1 and NF-κB by resveratrol and nicotinamide in alcohol-aflatoxin B1-induced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most commonly diagnosed cancer worldwide and is associated with poor prognosis. The current study aimed to assess the therapeutic efficacy of resveratrol when administered alone and in combination with nicotinamide against alcohol-aflatoxin B1-induced HCC. Results reveal that during the development and progression of cancer, there was a decline in the level of antioxidant enzymes catalase, glutathione peroxidase, glutathione reductase (GR), antioxidant glutathione, and glutathione S-transferase, which is an enzyme of detoxification pathways. Treatment of resveratrol restored the level of catalase and glutathione peroxidase toward normal in alcohol-aflatoxin B1-induced HCC; however, nicotinamide worked in concert with resveratrol only in upregulating the activity of glutathione reductase, glutathione level, and glutathione S-transferase. SIRT1 agonist resveratrol was observed to modulate the activity of antioxidant enzymes by negatively regulating the expression of nuclear factor-κB (NF-κB) in alcohol-aflatoxin B1-induced HCC, thereby suggesting a cross-talk between antioxidant enzymes SIRT1 and NF-κB during the development and progression of HCC and its therapeutics by resveratrol and nicotinamide.

Regulation of the Human Papillomavirus Life Cycle by DNA Damage Repair Pathways and Epigenetic Factors

Human papillomaviruses are the causative agents of cervical and other anogenital cancers along with approximately 60% of oropharyngeal cancers. These small double-stranded DNA viruses infect stratified epithelia and link their productive life cycles to differentiation. HPV proteins target cellular factors, such as those involved in DNA damage repair, as well as epigenetic control of host and viral transcription to regulate the productive life cycle. HPVs constitutively activate the ATM and ATR DNA repair pathways and preferentially recruit these proteins to viral genomes to facilitate productive viral replication. In addition, the sirtuin deacetylases along with histone acetyltransferases, including Tip60, are targeted in HPV infections to regulate viral transcription and replication. These pathways provide potential targets for drug therapy to treat HPV-induced disease.

Activation of TGR5 protects blood brain barrier via the BRCA1/Sirt1 pathway after middle cerebral artery occlusion in rats

BACKGROUND

The disruption of the blood-brain barrier (BBB) plays a critical event in the pathogenesis of ischemia stroke. TGR5 is recognized as a potential target for the treatment for neurologic disorders.

METHODS

This study investigated the roles of TGR5 activation in attenuating BBB damage and underlying mechanisms after middle cerebral artery occlusion (MCAO). Sprague-Dawley rats were subjected to model of MCAO and TGR5 agonist, INT777, was administered intranasally. Small interfering RNA (siRNA) for TGR5 and BRCA1 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes, brain water content, BBB permeability, neurological scores, Western blot, immunofluorescence staining and co- immunoprecipitation were evaluated.

RESULTS

Endogenous TGR5 and BRCA1 were upregulated in the injured hemisphere after MCAO and TGR5 expressed in endothelial cells. Treatment with INT777 alleviated brain water content and BBB permeability, reduced infarction volume and improved neurological scores at 24 h and 72 h after ischemia. INT777 administration increased BRCA1 and Sirt1 expression, as well as upregulated expressions of tight junction proteins. Ischemic damage induced interaction of TGR5 with BRCA1. TGR5 siRNA and BRCA1 siRNA significantly inhibited expressions of BRCA1 and Sirt1, aggravated BBB permeability and exacerbated stroke outcomes after MCAO. The protective effects of INT777 at 24 h after MCAO were also abolished by TGR5 siRNA or BRCA1 siRNA.

CONCLUSIONS

Our findings demonstrate that activating TGR5 could reduce BBB breakdown and improve neurological functions through BRCA1/Sirt1 signaling pathway after MCAO. TGR5 may serve as a potential new candidate to relieve brain injury after MCAO.

Rikkunshito attenuates induction of epithelial-mesenchymal switch via activation of Sirtuin1 in ovarian cancer cells

Rikkunshito, a traditional Japanese herbal medicine, improves appetite via activation of gastrointestinal hormone ghrelin pathway. The function of ghrelin is mediated by growth hormone secretagogue receptor (GHSR1a), and ghrelin has been known to possess diverse physiological functions including growth suppression of some cancer cells. Considering that increased ghrelin signaling by Rikkunshito could enhance sirtuin1 (SIRT1) activity in nervous system, we aimed to investigate the effect of Rikkunshito in ovarian cancer cells. Ovarian cancer cell lines were treated with Rikkunshito, and cellular viability, gene expressions and epithelial-mesenchymal transition (EMT) status were investigated. To investigate the involvement of SIRT1 by Rikkunshito in SKOV3 cancer cells, endogenous expression of SIRT1 was depleted using small interfering RNA (siRNA). Treatment with Rikkunshito elevated ghrelin, GHSR1a and SIRT1, while cellular viability was decreased. The treatment of Rikkunshito also inhibited cellular migration and invasion status in a dose-dependent manner, and these effects were translated to the enhanced EMT status, although the role of SIRT1 was not determined. Our study revealed a novel function of Rikkunshito in enhancing EMT status of ovarian cancer cells. Therefore, we would like to propose that Rikkunshito may be used as a novel adjunctive therapy in chemotherapy of ovarian cancer because platinum-based chemotherapy frequently used for the treatment of ovarian cancer inevitably impairs appetite.

Therapeutic efficacy of thermosensitive Pluronic hydrogel for codelivery of resveratrol microspheres and cisplatin in the treatment of liver cancer ascites

Ascites constitutes the most frequent decompensating event in patients with advanced liver cancer and is associated with poor quality of life and high mortality. Intraperitoneal chemotherapy appears to be a reliable treatment strategy for advanced liver cancer ascites. However, the rapid metabolism of drugs and ascites dilution limits the efficacy of chemotherapeutics. Therefore, the present study aimed to develop a novel thermosensitive hydrogel drug system for targeted therapy of advanced hepatocellular carcinoma (HCC) ascites through intraperitoneal administration. The system was prepared by blending resveratrol (RES) microspheres and cisplatin (DDP) into thermosensitive Pluronic F127 hydrogel. The in vitro anti-tumor activity against H22 cells indicated that the prepared drug system could initiate apoptosis and induce cell cycle arrest at the G1 phase. The mice model of ascites with advanced HCC was established to validate the therapeutic potential of the F127 hydrogel drug system in vivo. The results revealed that intraperitoneal administration of F127 hydrogel drug could significantly inhibit the number of ascites, the proliferation of tumor cells, micro-angiogenesis, and prolong the survival of mice, thus, augmenting the efficacy of intraperitoneal chemotherapy. Moreover, immunohistochemical staining revealed that the F127 hydrogel drug system was safe and presented low toxicity to major vital organs. Collectively, this study highlights the clinical application potential of the F127 hydrogel drug delivery system.

High Expression of SIRT1 Associates with the Doxorubicin Resistance of Breast Cancer through the Activation of Akt

Background and Purpose:

Although limited by side effects and development of resistance, doxorubicin still represent the most common chemotherapy for breast cancer. Thus, the identification of critical molecules to alleviate doxorubicin resistance is crucial. Here, we provide a molecular rationale for the breast cancer patients potentially benefitting from doxorubicin based on the expression levels of SIRT1, a identified member of longevity genes.

Methods:

SIRT1-overexpressed and SIRT1-knockdown breast cancer cells were established to investigate the functions of SIRT1 in regulating doxorubicin resistance both in vitro and in vivo. Cell proliferation was analyzed via CCK8 assay, cell apoptosis was studied by TUNEL anslysis. Molecule interaction was analyzed through co-immunoprecipitation and immunofluorescence techniques. Sensibility to doxorubicin was assessed in vivo through nude mice tumorigenicity experiment.

Results::

First, SIRT1 was found higher-expressed in breast cancer doxorubicin-resistant cells MCF-7/ADR than that in doxorubicin- sensitive cells MCF-7. Moreover, SIRT1-knockdown MCF-7/ADR cells showed higher susceptible to doxorubicin both in vitro and in vivo models, whereas overexpressing of SIRT1 obviously inhibited this phenotype. Accordingly, SIRT1 was found interacted with Akt, consequently promoted the activity of Akt in MCF-7/ADR cells in vitro and positively correlated with the expression of P-Akt in vivo. Reversion the activity of Akt partially downturned the doxorubicin-resistant effects mediated by SIRT1.

Conclusion:

This investigation suggested the value of SIRT1 as biomarker of response to doxorubicin, leading to the development of new tools for the management of breast cancer patients.

BIRC5 Expression is Regulated in Uterine Epithelium During the Estrous Cycle

Baculoviral inhibitor of apoptosis repeat-containing 5 (Birc5), also known as survivin, is a member of the inhibitor of apoptosis (IAP) family of proteins and regulates the size of tissues through cell division control. The uterus is the most dynamically sized organ among tissues during the estrous cycle. Although Birc5 is expressed in some terminally differentiated cells, the regulation of its expression in the uterus remains unknown. We investigated the regulation of Birc5 expression in the mouse uterus. RT-PCR analysis showed that Birc5 was expressed in various tissues, including the uterus; the expression level of Birc5 was significantly higher at the diestrus stage. Immunohistochemistry and Western blotting analysis revealed that Birc5 was more active in luminal and glandular epithelium than in endometrial stroma. In ovariectomized mice, Birc5 expression in the uterus was gradually increased by estrogen treatment; however, progesterone injection decreased its expression. Estrogen-induced Birc5 expression was blocked by treatment with estrogen receptor antagonist, ICI 182, 780 and progesterone-reduced Birc5 expression was inhibited by the progesterone receptor antagonist RU486. These results suggest that Birc5 expression is dynamically regulated by a combination of estrogen and progesterone via their receptor-mediated signaling.