Resveratrol fuels HER2 and ERα-positive breast cancer behaving as proteasome inhibitor

Roles of Glutathione and AP-1 in the Enhancement of Vitamin D-Induced Differentiation by Activators of the Nrf2 Signaling Pathway in Acute Myeloid Leukemia Cells

Active vitamin D derivatives (VDDs)-1α,25-dihydroxyvitamin D3/D2 and their synthetic analogs-are well-known inducers of cell maturation with the potential for differentiation therapy of acute myeloid leukemia (AML). However, their dose-limiting calcemic activity is a significant obstacle to using VDDs as an anticancer treatment. We have shown that different activators of the NF-E2-related factor-2/Antioxidant Response Element (Nrf2/ARE) signaling pathway, such as the phenolic antioxidant carnosic acid (CA) or the multiple sclerosis drug monomethyl fumarate (MMF), synergistically enhance the antileukemic effects of various VDDs applied at low concentrations in vitro and in vivo. This study aimed to investigate whether glutathione, the major cellular antioxidant and the product of the Nrf2/ARE pathway, can mediate the Nrf2-dependent differentiation-enhancing activity of CA and MMF in HL60 human AML cells. We report that glutathione depletion using L-buthionine sulfoximine attenuated the enhancing effects of both Nrf2 activators concomitant with downregulating vitamin D receptor (VDR) target genes and the activator protein-1 (AP-1) family protein c-Jun levels and phosphorylation. On the other hand, adding reduced glutathione ethyl ester to dominant negative Nrf2-expressing cells restored both the suppressed differentiation responses and the downregulated expression of VDR protein, VDR target genes, as well as c-Jun and P-c-Jun levels. Finally, using the transcription factor decoy strategy, we demonstrated that AP-1 is necessary for the enhancement by CA and MMF of 1α,25-dihydroxyvitamin D3-induced VDR and RXRα protein expression, transactivation of the vitamin D response element, and cell differentiation. Collectively, our findings suggest that glutathione mediates, at least in part, the potentiating effect of Nrf2 activators on VDDs-induced differentiation of AML cells, likely through the positive regulation of AP-1.

Phytometabolites as modulators of breast cancer: a comprehensive review of mechanistic insights

Breast cancer (BC) is a highly debilitating malignancy affecting females globally and imposing a substantial burden on healthcare systems in both developed and developing nations. Despite the application of conventional therapeutic modalities such as chemotherapy, radiation therapy, and hormonal intervention, BC frequently exhibits resistance, necessitating the urgent development of novel, cost-effective, and accessible treatment strategies. In this context, there is a growing scientific interest in exploring the pharmacological potential of chemical compounds derived from botanical sources, which often exhibit notable biological activity. Extensive in vitro and in vivo investigations have revealed the capacity of these compounds, referred to as phytochemicals, to attenuate the metastatic cascade and reduce the risk of cancer dissemination. These phytochemicals exert their effects through modulation of key molecular and metabolic processes, including regulation of the cell cycle, induction of apoptotic cell death, inhibition of angiogenesis, and suppression of metastatic progression. To shed light on the latest advancements in this field, a comprehensive review of the scientific literature has been conducted, focusing on secondary metabolite agents that have recently been investigated and have demonstrated promising anticancer properties. This review aims to delineate their underlying mechanisms of action and elucidate the associated signaling pathways, thereby contributing to a deeper understanding of their therapeutic potential in the context of BC management.

SIRT6 promotes metastasis and relapse in HER2-positive breast cancer

The histone deacetylase sirtuin 6 (SIRT6) has been endowed with anti-cancer capabilities in many tumor types. Here, we investigate the impact of SIRT6-overexpression (SIRT6-OE) in Delta16HER2 mice, which are a bona fide model of HER2-positive breast cancer. After an initial delay in the tumor onset, SIRT6-OE induces a more aggressive phenotype of Delta16HER2 tumors promoting the formation of higher number of tumor foci and metastases than controls. This phenotype of SIRT6-OE tumors is associated with cancer stem cell (CSC)-like features and tumor dormancy, and low senescence and oxidative DNA damage. Accordingly, a sub-set of HER2-positive breast cancer patients with concurrent SIRT6-OE has a significant poorer relapse-free survival (RFS) probability than patients with low expression of SIRT6. ChIP-seq, RNA-seq and RT-PCR experiments indicate that SIRT6-OE represses the expression of the T-box transcription factor 3 (Tbx3) by deacetylation of H3K9ac. Accordingly, loss-of-function mutations of TBX3 or low TBX3 expression levels are predictive of poor prognosis in HER2-positive breast cancer patients. Our work indicates that high levels of SIRT6 are indicative of poor prognosis and high risk of metastasis in HER2-positive breast cancer and suggests further investigation of TBX3 as a downstream target of SIRT6 and co-marker of poor-prognosis. Our results point to a breast cancer subtype-specific effect of SIRT6 and warrant future studies dissecting the mechanisms of SIRT6 regulation in different breast cancer subtypes.

Evolution of Natural Product Scaffolds as Potential Proteasome Inhibitors in Developing Cancer Therapeutics

Homeostasis between protein synthesis and degradation is a critical biological function involving a lot of precise and intricate regulatory systems. The ubiquitin-proteasome pathway (UPP) is a large, multi-protease complex that degrades most intracellular proteins and accounts for about 80% of cellular protein degradation. The proteasome, a massive multi-catalytic proteinase complex that plays a substantial role in protein processing, has been shown to have a wide range of catalytic activity and is at the center of this eukaryotic protein breakdown mechanism. As cancer cells overexpress proteins that induce cell proliferation, while blocking cell death pathways, UPP inhibition has been used as an anticancer therapy to change the balance between protein production and degradation towards cell death. Natural products have a long history of being used to prevent and treat various illnesses. Modern research has shown that the pharmacological actions of several natural products are involved in the engagement of UPP. Over the past few years, numerous natural compounds have been found that target the UPP pathway. These molecules could lead to the clinical development of novel and potent anticancer medications to combat the onslaught of adverse effects and resistance mechanisms caused by already approved proteasome inhibitors. In this review, we report the importance of UPP in anticancer therapy and the regulatory effects of diverse natural metabolites, their semi-synthetic analogs, and SAR studies on proteasome components, which may aid in discovering a new proteasome regulator for drug development and clinical applications.

HER2-Displaying M13 Bacteriophages induce Therapeutic Immunity against Breast Cancer

Simple Summary

The high incidence and death rates of breast cancer make the development of new therapies an urgent need. The introduction into the clinic of the anti-HER2 monoclonal antibody trastuzumab considerably improved the overall survival and time-to-disease progression of patients with HER2-positive breast cancer. However, many patients do not benefit from it because of resistance to therapy. Cancer vaccines, by inducing into the patient an anti-cancer specific immunity, might represent an alternative immunotherapeutic approach, but despite promises, so far no anti-HER2 cancer vaccine has been approved for human use. In this study, we propose therapeutic phage-based vaccines, against HER2 and its aggressive isoform Δ16HER2, able to elicit a protective immunity and potentially capable of preventing relapse in HER2-positive breast cancer patients, even in those who develop trastuzumab resistance.

Abstract

The advent of trastuzumab has significantly improved the prognosis of HER2-positive (HER2+) breast cancer patients; nevertheless, drug resistance limits its clinical benefit. Anti-HER2 active immunotherapy represents an attractive alternative strategy, but effective immunization needs to overcome the patient’s immune tolerance against the self-HER2. Phage display technology, taking advantage of phage intrinsic immunogenicity, permits one to generate effective cancer vaccines able to break immune tolerance to self-antigens. In this study, we demonstrate that both preventive and therapeutic vaccination with M13 bacteriophages, displaying the extracellular (EC) and transmembrane (TM) domains of human HER2 or its Δ16HER2 splice variant on their surface (ECTM and Δ16ECTM phages), delayed mammary tumor onset and reduced tumor growth rate and multiplicity in ∆16HER2 transgenic mice, which are tolerant to human ∆16HER2. This antitumor protection correlated with anti-HER2 antibody production. The molecular mechanisms underlying the anticancer effect of vaccine-elicited anti-HER2 antibodies were analyzed in vitro against BT-474 human breast cancer cells, sensitive or resistant to trastuzumab. Immunoglobulins (IgG) purified from immune sera reduced cell viability mainly by impairing ERK phosphorylation and reactivating retinoblastoma protein function in both trastuzumab-sensitive and -resistant BT-474 cells. In conclusion, we demonstrated that phage-based HER2 vaccines impair mammary cancer onset and progression, opening new perspectives for HER2+ breast cancer treatment.

Resveratrol Treatment Prevents Increase of Mast Cells in Both Murine OVA Enteritis and IL-10-/- Colitis

Mast cells are involved in allergic and other inflammatory diseases. The polyphenol resveratrol is known for its anti-inflammatory properties and may be used as nutraceutical in mast cell associated diseases. We analyzed the effect of resveratrol on mast cells in vivo in ovalbumin-induced allergic enteritis as well as experimental colitis in IL-10^−/− mice which received resveratrol via drinking water. Treatment with resveratrol prevented the increase in mast cells in both allergic enteritis and chronic colitis in duodenum as well as in colon. Further, it delayed the onset of diseases symptoms and ameliorated diseases associated parameters such as tissue damage as well as inflammatory cell infiltration in affected colon sections. In addition to the findings in vivo, resveratrol inhibited IgE-dependent degranulation and expression of pro-inflammatory cytokines such as TNF-α in IgE/DNP-activated as well as in LPS-activated bone marrow-derived mast cells. These results indicate that resveratrol may be considered as an anti-allergic and anti-inflammatory plant-derived component for the prevention or treatment of mast cell-associated disorders of the gastrointestinal tract.

Natural products are an important source for proteasome regulating agents

BACKGROUND

Natural medicines have a long history in the prevention and treatment of various diseases in East Asian region, especially in China. Modern research has proved that the pharmacological effects of numerous natural medicines involve the participation of ubiquitin proteasome system (UPS). UPS can degrade the unwanted and damaged proteins widely distributed in the nucleus and cytoplasm of various eukaryotes.

PURPOSE

The objective of the present study was to review and discuss the regulatory effects of natural products and extracts on proteasome components, which may help to find new proteasome regulators for drug development and clinical applications.

METHODS

The related information was compiled using the major scientific databases, such as CNKI, Elsevier, ScienceDirect, PubMed, SpringerLink, Wiley Online, and GeenMedical. The keywords "natural product" and "proteasome" were applied to extract the literature. Nature derived extracts, compounds and their derivatives involved in proteasome regulation were included, and the publications related to synthetic proteasome agents were excluded.

RESULTS

The pharmacological effects of more than 80 natural products and extracts derived from phytomedicines related to the proteasome regulation were reviewed. These natural products were classified according to their chemical properties. We also summarized some laws of action of natural products as proteasome regulators in the treatment of diseases, and listed the action characteristics of the typical natural products.

CONCLUSION

Natural products derived from nature can induce the degradation of damaged proteins through UPS or act as regulators to directly regulate the activity of proteasome. But few proteasome modulators are applied clinically. Summary of known rules for proteasome modulators will contribute to discover, modify and synthesize more proteasome modulators for clinical applications.

Beneficial Oxidative Stress-Related trans-Resveratrol Effects in the Treatment and Prevention of Breast Cancer

Resveratrol is one of the most investigated polyphenols for its multiple biological activities and many beneficial effects. These are mainly related to its ability to scavenge free radicals and reduce oxidative stress. Resveratrol has also been shown to have the ability to stimulate the production of antioxidant enzymes, which interact with numerous signaling pathways involved in tumor development, and to possess side effects associated with the use of chemotherapy drugs. In this review article we summarized the main discoveries about the impact resveratrol can have in helping to prevent, as well as adjuvant treating, breast cancer. A brief overview of the primary sources of resveratrol as well as some approaches for improving its bioavailability have been also discussed.

Effects and mechanisms of dietary bioactive compounds on breast cancer prevention

Breast cancer (BC) is the most often diagnosed cancer among females globally and has become an increasing global health issue over the last decades. Despite the substantial improvement in screening methods for initial diagnosis, effective therapy remains lacking. Still, there has been high recurrence and disease progression after treatment of surgery, endocrine therapy, chemotherapy, and radiotherapy. Considering this view, there is a crucial requirement to develop safe, freely accessible, and effective anticancer therapy for BC. The dietary bioactive compounds as auspicious anticancer agents have been recognized to be active and their implications in the treatment of BC with negligible side effects. Hence, this review focused on various dietary bioactive compounds as potential therapeutic agents in the prevention and treatment of BC with the mechanisms of action. Bioactive compounds have chemo-preventive properties as they inhibit the proliferation of cancer cells, downregulate the expression of estrogen receptors, and cell cycle arrest by inducing apoptotic settings in tumor cells. Therapeutic drugs or natural compounds generally incorporate engineered nanoparticles with ideal sizes, shapes, and enhance their solubility, circulatory half-life, and biodistribution. All data of in vitro, in vivo, and clinical studies of dietary bioactive compounds and their impact on BC were collected from Science Direct, PubMed, and Google Scholar. The data of chemopreventive and anticancer activity of dietary bioactive compounds were collected and orchestrated in a suitable place in the review. These shreds of data will be extremely beneficial to recognize a series of additional diet-derived bioactive compounds to treat BC with the lowest side effects.

Chemo-Preventive Action of Resveratrol: Suppression of p53-A Molecular Targeting Approach

Extensive experimental, clinical, and epidemiological evidence has explained and proven that products of natural origin are significantly important in preventing and/or ameliorating various disorders, including different types of cancer that researchers are extremely focused on. Among these studies on natural active substances, one can distinguish the emphasis on resveratrol and its properties, especially the potential anticancer role. Resveratrol is a natural product proven for its therapeutic activity, with remarkable anti-inflammatory properties. Various other benefits/actions have also been reported, such as cardioprotective, anti-ageing, antioxidant, etc. and its rapid digestion/absorption as well. This review aims to collect and present the latest published studies on resveratrol and its impact on cancer prevention, molecular signals (especially p53 protein participation), and its therapeutic prospects. The most recent information regarding the healing action of resveratrol is presented and concentrated to create an updated database focused on this topic presented above.

Arctigenin inhibits human breast cancer cell proliferation, migratory and invasive abilities and epithelial to mesenchymal transition by targeting 4EBP1

Breast cancer (BC) is one of the most common types of cancer with the highest morbidity rate amongst all cancers in women worldwide. Arctigenin is isolated from the seeds of Asteraceae lappa and exhibits anti-inflammatory and anti-viral effects. The present study aimed to investigate the effect of arctigenin on BC cells and to explore the regulation of arctigenin on eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) expression. To do so, MDA-MB-231 and BT549 cells were treated with arctigenin at various concentrations (0, 5, 10, 20 and 40 µM). Cells treated with 40 µM arctigenin were transfected with pcDNA3.1-4EBP1 or NC control. Cell Counting Kit-8 assay was used to determine cell proliferation, reverse transcription quantitative PCR was used to evaluate the transfection efficiency, western blotting was used to detect relative protein expression and Transwell assays were performed to evaluate the migratory and invasive abilities of BC cells. The results demonstrated that arctigenin could inhibit the proliferation, migratory and invasive abilities, and epithelial to mesenchymal transition (EMT) of MDA-MB-231 and BT549 cells. Furthermore, arctigenin downregulated the expression of 4EBP1 in MDA-MB-231 and BT549 cells, whereas 4EBP1 overexpression could reverse the inhibiting effect of arctigenin on proliferation, migratory and invasive abilities, and EMT in MDA-MB-231 and BT549 cells. The findings suggested that arctigenin may inhibit human BC cell proliferation, migratory and invasive abilities, and EMT by targeting 4EBP1.

Towards resolving the enigma of the dichotomy of resveratrol: cis- and trans-resveratrol have opposite effects on TyrRS-regulated PARP1 activation

Unlike widely perceived, resveratrol (RSV) decreased the average lifespan and extended only the replicative lifespan in yeast. Similarly, although not widely discussed, RSV is also known to evoke neurite degeneration, kidney toxicity, atherosclerosis, premature senescence, and genotoxicity through yet unknown mechanisms. Nevertheless, in vivo animal models of diseases and human clinical trials demonstrate inconsistent protective and beneficial effects. Therefore, the mechanism of action of RSV that elicits beneficial effects remains an enigma. In a previously published work, we demonstrated structural similarities between RSV and tyrosine amino acid. RSV acts as a tyrosine antagonist and competes with it to bind to human tyrosyl-tRNA synthetase (TyrRS). Interestingly, although both isomers of RSV bind to TyrRS, only the cis-isomer evokes a unique structural change at the active site to promote its interaction with poly-ADP-ribose polymerase 1 (PARP1), a major determinant of cellular NAD+-dependent stress response. However, retention of trans-RSV in the active site of TyrRS mimics its tyrosine-bound conformation that inhibits the auto-poly-ADP-ribos(PAR)ylation of PARP1. Therefore, we proposed that cis-RSV-induced TyrRS-regulated auto-PARylation of PARP1 would contribute, at least in part, to the reported health benefits of RSV through the induction of protective stress response. This observation suggested that trans-RSV would inhibit TyrRS/PARP1-mediated protective stress response and would instead elicit an opposite effect compared to cis-RSV. Interestingly, most recent studies also confirmed the conversion of trans-RSV and its metabolites to cis-RSV in the physiological context. Therefore, the finding that cis-RSV and trans-RSV induce two distinct conformations of TyrRS with opposite effects on the auto-PARylation of PARP1 provides a potential molecular basis for the observed dichotomic effects of RSV under different experimental paradigms. However, the fact that natural RSV exists as a diastereomeric mixture of its cis and trans isomers and cis-RSV is also a physiologically relevant isoform has not yet gained much scientific attention.

Gemcitabine potentiates anti-tumor effect of resveratrol on pancreatic cancer via down-regulation of VEGF-B

PURPOSE

In our previous study, we discovered that resveratrol (RSV) had potential tumor-promoting effect on pancreatic cancer (PaCa) via up-regulation of VEGF-B. Therefore, we assumed that a pharmacological inhibitor of VEGF-B should potentiate the anti-tumor effect of RSV on PaCa.

METHODS

Real-time PCR and western blotting were used to examine VEGF-B mRNA and protein levels. Cell viability and cell apoptosis were assessed by CCK-8 assay and flow cytometry analysis, respectively. PaCa cell-bearing nude mice were used to evaluate the anti-cancer effects of single treatment or co-administration of RSV and gemcitabine (GEM).

RESULTS

We found that treatment with GEM alone dramatically decreased VEGF-B expression in comparison with control group, indicating that GEM is a potential pharmacological inhibitor of VEGF-B in PaCa. The co-administration of RSV and GEM significantly lowered expression of VEGF-B and increased phosphorylation level of GSK3β at Ser9 when compared to RSV alone treatment either in vitro or in vivo. Combination of RSV and GEM significantly increased cell death and apoptosis of PaCa cells in vitro and inhibited tumor growth in vivo in comparison with RSV or GEM alone treatment. Furthermore, we found that the anti-tumor effect in combination group was dramatically weakened after VEGF-B overexpressed in PaCa cells.

CONCLUSION

These results suggest that VEGF-B signaling pathway plays an important role in the development of PaCa and combination of GEM and RSV would be a promising modality for clinical PaCa therapy.

Acetylshikonin isolated from Lithospermum erythrorhizon roots inhibits dihydrofolate reductase and hampers autochthonous mammary carcinogenesis in Δ16HER2 transgenic mice

Breast cancer (BC) is the most common cancer in women and, among different BC subtypes, triple negative (TN) and human epidermal growth factor receptor 2 (HER2)-positive BCs have the worst prognosis. In this study, we investigated the anticancer activity of the root ethanolic and hexane extracts from Lithospermum erythrorhizon, a traditional Chinese herbal medicine known also as tzu ts'ao or tzu-ken, against in vitro and in vivo models of TNBC and HER2-positive BC. Treatment with L. erythrorhizon root extracts resulted in a dose-dependent inhibition of BC cell viability and in a significant reduction of the growth of TNBC cells transplanted in syngeneic mice. Acetylshikonin, a naphthoquinone, was identified as the main bioactive component in extracts and was responsible for the observed antitumor activity, being able to decrease BC cell viability and to interfere with autochthonous mammary carcinogenesis in Δ16HER2 transgenic mice. Acetylshikonin anticancer effect depends on its ability to act as a potent inhibitor of dihydrofolate reductase (DHFR), to down-regulate key mediators governing cancer growth and progression, such as HER2, Src and STAT3, and to induce apoptosis by caspase-3 activation. The accumulation of acetylshikonin in blood samples as well as in brain, kidney, liver and tumor tissues was also investigated by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) highlighting that L. erythrorhizon treatment is effective in delivering the active compound into the target tissues. These results provide evidence that L. erythrorhizon extract and in particular its main component acetylshikonin are effective against aggressive BC subtypes and reveal new acetylshikonin mechanisms of action.

Berberine and Emodin abrogates breast cancer growth and facilitates apoptosis through inactivation of SIK3-induced mTOR and Akt signaling pathway

Salt-inducible kinases 3 (SIK3) belong to the AMPK-related family of kinases, which have been implicated in the regulation of cell metabolism, cell polarity remodelling, and epithelial-mesenchymal transition. Elevated SIK3 expressions in breast cancer cells are shown to contribute to tumorigenesis; however, the underlying mechanism remains to be elucidated. In this study, we demonstrate that SIK3 expression is upregulated and concurrently high expression of SIK3 is associated with poor survival in breast cancer. Specifically, SIK3 knockdown revealed that SIK3 is required for the mTOR/Akt signaling pathway and proliferation of breast cancer cells. Furthermore, our findings showed that Emodin (EMO) combined with Berberine (BBR) significantly inhibited SIK3 activity, leading to reduced cell growth, increased cell cycle arrest and apoptosis in breast cancer cells, but not in non-malignant breast epithelial cell line. Mechanistic studies further reveal that EMO and BBR in combined treatment inhibited SIK3-potentiated mTOR-mediated aerobic glycolysis and cell growth in breast cancer cells. Moreover, combination treatments attenuate Akt signaling, thereby inducing G0/G1 phase cell cycle arrest and apoptosis of breast cancer cells in a SIK3-dependent manner. CRISPR/Cas9 or siRNA-mediated SIK3 knockout/knockdown showed an opposite trend in both the luminal and basal-like breast cancer. Collectively, our findings reveal that combination of EMO and BBR attenuates SIK3-driven tumor growth in breast cancer, and thus, EMO and BBR might be a novel SIK3 inhibitor explored into the prevention of breast cancer.

Breast Tumor Microenvironment: Emerging target of therapeutic phytochemicals

Triple negative breast cancer (TNBC) is the most aggressive and challenging form of breast cancers. Tumor microenvironment (TME) of TNBC is associated with induction of metastasis, immune system suppression, escaping immune detection and drug resistance. TME is highly complex and heterogeneous, consists of tumor cells, stromal cells and immune cells. The rapid expansion of tumors induce hypoxia, which concerns the reprogramming of TME components. The reciprocal communication of tumor cells and TME cells predisposes cancer cells to metastasis by modulation of developmental pathways, Wnt, notch, hedgehog and their related mechanisms in TME. Dietary phytochemicals are non-toxic and associated with various human health benefits and remarkable spectrum of biological activities. The phytochemicals serve as vital resources for drug discovery and also as a source for breast cancer therapy. The novel properties of dietary phytochemicals propose platform for modulation of tumor signaling, overcoming drug resistance, and targeting TME. Therefore, TME could serve as promising target for the treatment of TNBC. This review presents current status and implications of experimentally evaluated therapeutic phytochemicals as potential targeting agents of TME, potential nanosystems for targeted delivery of phytochemicals and their current challenges and future implications in TNBC treatment. The dietary phytochemicals especially curcumin with significant delivery system could prevent TNBC development as it is considered safe and well tolerated in phase II clinical trials.

Insights on the Effects of Resveratrol and Some of Its Derivatives in Cancer and Autoimmunity: A Molecule with a Dual Activity

In recent years, the interest in natural compounds exerting immunoregulatory effects has enormously increased. Among these, the polyphenol resveratrol, found in a variety of foods and beverages, including red grapes and red wine, has been demonstrated to exert both in vitro and in vivo biological activities. More specifically, it has antiaging, cardioprotective, antioxidant, immunomodulatory, anti-inflammatory and chemopreventive activities. Due to its anti-proliferative, pro-apoptotic and immunoregulatory effects, resveratrol has gained substantial attention for the treatment of cancer or autoimmunity, which represent frequently diagnosed diseases with important consequences for the health of the patients affected. The aim of the present review is to focus on the role of resveratrol in the modulation of cancer as well as of several organ-specific or systemic autoimmune diseases, including autoimmune hepatitis, type 1 diabetes mellitus, inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis.

A novel 3'-tRNAGlu-derived fragment acts as a tumor suppressor in breast cancer by targeting nucleolin

tRNA-derived fragments (tRFs) have been defined as a novel class of small noncoding RNAs. tRFs have been reported to be deregulated in cancer, but their biologic function remains to be fully understood. We have identified a new tRF (named tRF3E), derived from mature tRNAGlu, that is specifically expressed in healthy mammary glands but not in breast cancer (BC). Consistently, tRF3E levels significantly decrease in the blood of patients with epidermal growth factor receptor 2 (HER2)-positive BC reflecting tumor status (control > early cancer > metastatic cancer). tRF3E down-regulation was recapitulated in Δ16HER2 transgenic mice, representing a BC preclinical model. Pulldown assays, used to search for proteins capable to selectively bind tRF3E, have shown that this tRF specifically interacts with nucleolin (NCL), an RNA-binding protein overexpressed in BC and able to repress the translation of p53 mRNA. The binding properties of NCL-tRF3E complex, predicted in silico and analyzed by EMSA assays, are congruent with a competitive displacement of p53 mRNA by tRF3E, leading to an increased p53 expression and consequently to a modulation of cancer cell growth. Here, we provide evidence that tRF3E plays an important role in the pathogenesis of BC displaying tumor-suppressor functions through a NCL-mediated mechanism.-Falconi, M., Giangrossi, M., Elexpuru Zabaleta, M., Wang, J., Gambini, V., Tilio, M., Bencardino, D., Occhipinti, S., Belletti, B., Laudadio, E., Galeazzi, R., Marchini, C., Amici, A. A novel 3'-tRNAGlu-derived fragment acts as a tumor suppressor in breast cancer by targeting nucleolin.

Resveratrol and other dietary polyphenols are inhibitors of estrogen metabolism in human breast cancer cells

Polyphenols in foods and dietary supplements are commonly used for the prevention and treatment of a variety of malignancies, including breast cancer. However, daily intake by patients with breast cancer is controversial, as these compounds may stimulate cancer growth. Estrogens serve key roles in breast cancer cell proliferation; therefore, understanding the interaction between endogenous steroid hormones and natural dietary polyphenols is essential. Currently, comprehensive knowledge regarding these effects remains limited. The current review summarizes the dose-dependent in vitro and in vivo interactions of resveratrol and other dietary polyphenols with estrogen precursors, active estrogens, catechol estrogens and their respective glucuronidated, sulfated, glutathionated or O-methylated metabolites in estrogen receptor alpha negative (ERα-) and positive (ERα+) breast cancer. Which estrogen-metabolizing enzymes are affected by polyphenols is also reviewed in detail. Furthermore, the impacts of dose and therapy duration on disease development and progression in patients with breast cancer are discussed. The present article is part of a Special Issue titled 'CSR 2018'.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

A panel of biomarkers for skin squamous cell carcinoma: various functional entities and differential responses to resveratrol

In contrast to the highly malignant melanoma, skin squamous cell carcinoma (SCC) usually presents with lower morbidity. However, its incidence has been alarmingly rising worldwide and is a public health burden, let alone the current SCC cancer classification scheme is inadequate. Due to its features of progressing along different pathologic stages, early detection of precancerous lesions with accurate molecular markers would be desirable for cancer prevention and treatment. In the present study, using immunohistochemical staining of 85 clinical samples, we profiled the expression of a panel of ten proteins from five functional divisions implicated in SCC development, i.e. cytokeratins, intercellular molecules, chaperone proteins, transcription factors, and mitochondrial redox enzymes. The differential alterations of the proteins in SCC cell lines SCL12 and COLO16, upon resveratrol therapy, were also examined by immunocytochemistry (ICC). Our data reveal that, while all these proteins show significant correlation with cancer initiation and/or progression, a comprehensive panel encompassing a range of biologic functions, instead of a single marker, will provide prognostic value in SCC diagnosis and management. Additionally, the strong correlation among the proteins with cancer stages implies their distinct roles in SCC pathogenesis and contributions to the therapeutic effects of resveratrol, which is demonstrated in the resveratrol-sensitive COLO16 cells, but not in the resveratrol-resistant SCL12 cells.

Steroid Receptor Signallings as Targets for Resveratrol Actions in Breast and Prostate Cancer

Extensive research over the past 25 years in hormone-dependent cancers, such as breast cancer and prostate cancer, has identified the molecular mechanisms driven by steroid receptors, elucidating the interplay between genomic and non-genomic steroid receptors mechanism of action. Altogether, these mechanisms create the specific gene expression programs that contribute to endocrine therapy resistance and cancer progression. These findings, on the bidirectional molecular crosstalk between steroid and growth factor receptors pathways in endocrine resistance, suggest the use of multi-target inhibitors together with endocrine therapies, for treating resistant disease. In this review we will discuss the novel understanding on the chemopreventive and anti-cancer activities of Resveratrol (3,5,4′-trihydroxy-stilbene) (RSV), a phytoalexin found in grapes acting on a plethora of targets. We will highlight Resveratrol effect on steroid receptors signalling and its potential use in the treatment of hormone-dependent cancer. Understanding the molecular mechanisms by which the bioactive compound influences cancer cell behaviour, by interfering with steroid receptors functional activity, will help to advance the design of combination strategies to increase the rate of complete and durable clinical response in patients.

Possible role of phytoestrogens in breast cancer via GPER-1/GPR30 signaling

Estrogens generated within endocrine organs and the reproductive system act as ligands for at least three types of estrogen receptors. Estrogen receptors α (ERα) and β (ERβ) belong to the so-called classical family of estrogen receptors, whereas the G protein-coupled receptor GPR30, also known as GPER-1, has been described as a novel estrogen receptor sited in the cell membrane of target cells. Furthermore, these receptors are under stimulation of a family of exogenous estrogens, known as phytoestrogens, which are a diverse group of non-steroidal plant compounds derived from plant food consumed by humans and animals. Because phytoestrogens are omnipresent in our daily diet, they are becoming increasingly important in both human health and disease. Recent evidence indicates that in addition to classical estrogen receptors, phytoestrogens also activate GPER-1 a relevant observation since GPER-1 is involved in several physiopathological disorders and especially in estrogen-dependent diseases such as breast cancer.The first estrogen receptors discovered were the classical ERα and ERβ, but from an evolutionary point of view G protein-coupled receptors trace their origins in history to over a billion years ago suggesting that estrogen receptors like GPER-1 may have been the targets of choice for ancient phytoestrogens and/or estrogens.This review provides a comprehensive and systematic literature search on phytoestrogens and its relationship with classical estrogen receptors and GPER-1 including its role in breast cancer, an issue still under discussion.

The "Yin and Yang" of Natural Compounds in Anticancer Therapy of Triple-Negative Breast Cancers

Among the different types of breast cancers, triple-negative breast cancers (TNBCs) are highly aggressive, do not respond to conventional hormonal/human epidermal growth factor receptor 2 (HER2)-targeted interventions due to the lack of the respective receptor targets, have chances of early recurrence, metastasize, tend to be more invasive in nature, and develop drug resistance. The global burden of TNBCs is increasing regardless of the number of cytotoxic drugs being introduced into the market each year as they have only moderate efficacy and/or unforeseen side effects. Therefore, the demand for more efficient therapeutic interventions, with reduced side effects, for the treatment of TNBCs is rising. While some plant metabolites/derivatives actually induce the risk of cancers, many plant-derived active principles have gained attention as efficient anticancer agents against TNBCs, with fewer adverse side effects. Here we discuss the possible oncogenic molecular pathways in TNBCs and how the purified plant-derived natural compounds specifically target and modulate the genes and/or proteins involved in these aberrant pathways to exhibit their anticancer potential. We have linked the anticancer potential of plant-derived natural compounds (luteolin, chalcones, piperine, deguelin, quercetin, rutin, fisetin, curcumin, resveratrol, and others) to their ability to target multiple dysregulated signaling pathways (such as the Wnt/β-catenin, Notch, NF-κB, PI3K/Akt/mammalian target of rapamycin (mTOR), mitogen-activated protein kinase (MAPK) and Hedgehog) leading to suppression of cell growth, proliferation, migration, inflammation, angiogenesis, epithelial-mesenchymal transition (EMT) and metastasis, and activation of apoptosis in TNBCs. Plant-derived compounds in combination with classical chemotherapeutic agents were more efficient in the treatment of TNBCs, possibly with lesser side effects.

Induction of ubiquitin C (UBC) gene transcription is mediated by HSF1: role of proteotoxic and oxidative stress

The polyubiquitin gene ubiquitin C (UBC) is considered a stress protective gene and is upregulated under various stressful conditions, which is probably a consequence of an increased demand for ubiquitin in order to remove toxic misfolded proteins. We previously identified heat shock elements (HSEs) within the UBC promoter, which are responsible for heat shock factor (HSF)1‐driven induction of the UBC gene and are activated by proteotoxic stress. Here, we determined the molecular players driving the UBC gene transcriptional response to arsenite treatment, mainly addressing the role of the nuclear factor‐erythroid 2‐related factor 2 (Nrf2)‐mediated antioxidant pathway. Exposure of HeLa cells to arsenite caused a time‐dependent increase of UBCmRNA, while cell viability and proteasome activity were not affected. Nuclear accumulation of HSF1 and Nrf2 transcription factors was detected upon both arsenite and MG132 treatment, while HSF2 nuclear levels increased in MG132‐treated cells. Notably, siRNA‐mediated knockdown of Nrf2 did not reduce UBC transcription under either basal or stressful conditions, but significantly impaired the constitutive and inducible expression of well‐known antioxidant response element‐dependent genes. A chromatin immunoprecipitation assay consistently failed to detect Nrf2 binding to the UBC promoter sequence. By contrast, depletion of HSF1, but not HSF2, significantly compromised stress‐induced UBC expression. Critically, HSF1‐mediated UBC trans‐activation upon arsenite exposure relies on transcription factor binding to previously mapped distal HSEs, as demonstrated to occur under proteasome inhibition. These data highlight HSF1 as the pivotal transcription factor that translates different stress signals into UBC gene transcriptional induction.

Resveratrol Inhibits Key Steps of Steroid Metabolism in a Human Estrogen-Receptor Positive Breast Cancer Model: Impact on Cellular Proliferation

The role of resveratrol (RES) in preventing breast cancer is controversial, as low concentrations may stimulate the proliferation of estrogen-receptor alpha positive (ERα+) breast cancer cells. As metabolism is the key factor in altering cellular estrogens, thereby influencing breast tumor growth, we investigated the effects of RES on the formation of estrogen metabolites, namely 4-androstene-3,17-dione (AD), dehydroepiandrosterone (DHEA), dehydroepiandrosterone-3-O-sulfate (DHEA-S), estrone (E1), estrone-3-sulfate (E1-S), 17β-estradiol (E2), 17β-estradiol-3-O-(β-D-glucuronide) (E2-G), 17β-estradiol-3-O-sulfate (E2-S), 16α-hydroxy-17β-estradiol (estriol, E3), and testosterone (T) in ERα- MDA-MB-231 and ERα+ MCF-7 cells. Incubation of both of the cell lines with the hormone precursors DHEA and E1 revealed that sulfation and glucuronidation were preferred metabolic pathways for DHEA, E1 and E2 in MCF-7 cells, compared with in MDA-MB-231 cells, as the V_max values were significantly higher (DHEA-S: 2873.0 ± 327.4 fmol/10⁶ cells/h, E1-S: 30.4 ± 2.5 fmol/10⁶ cells/h, E2-S: 24.7 ± 4.9 fmol/10⁶ cells/h, E2-G: 7.29 ± 1.36 fmol/10⁶ cells/h). RES therefore significantly inhibited DHEA-S, E1-S, E2-S and E2-G formation in MCF-7, but not in MDA-MB-231 cells (K_is: E2-S, 0.73 ± 0.07 μM < E1-S, 0.94 ± 0.03 μM < E2-G, 7.92 ± 0.24 μM < DHEA-S, 13.2 ± 0.2 μM). Suppression of these metabolites subsequently revealed twofold higher levels of active E2, concomitant with an almost twofold increase in MCF-7 cell proliferation, which was the most pronounced upon the addition of 5 μM RES. As the content of RES in food is relatively low, an increased risk of breast cancer progression in women is likely to only be observed following the continuous consumption of high-dose RES supplements. Further long-term human studies simultaneously monitoring free estrogens and their conjugates are therefore highly warranted to evaluate the efficacy and safety of RES supplementation, particularly in patients diagnosed with ERα+ breast cancer.

Targeting protein quality control pathways in breast cancer

The efficient production, folding, and secretion of proteins is critical for cancer cell survival. However, cancer cells thrive under stress conditions that damage proteins, so many cancer cells overexpress molecular chaperones that facilitate protein folding and target misfolded proteins for degradation via the ubiquitin-proteasome or autophagy pathway. Stress response pathway induction is also important for cancer cell survival. Indeed, validated targets for anti-cancer treatments include molecular chaperones, components of the unfolded protein response, the ubiquitin-proteasome system, and autophagy. We will focus on links between breast cancer and these processes, as well as the development of drug resistance, relapse, and treatment.

Cancer Chemoprevention by Resveratrol: The p53 Tumor Suppressor Protein as a Promising Molecular Target

Increasing epidemiological and experimental evidence has demonstrated an inverse relationship between the consumption of plant foods and the incidence of chronic diseases, including cancer. Microcomponents that are naturally present in such foods, especially polyphenols, are responsible for the benefits to human health. Resveratrol is a diet-derived cancer chemopreventive agent with high therapeutic potential, as demonstrated by different authors. The aim of this review is to collect and present recent evidence from the literature regarding resveratrol and its effects on cancer prevention, molecular signaling (especially regarding the involvement of p53 protein), and therapeutic perspectives with an emphasis on clinical trial results to date.