Benzyl Isothiocyanate (BITC) Induces Reactive Oxygen Species-dependent Repression of STAT3 Protein by Down-regulation of Specificity Proteins in Pancreatic Cancer

Phytochemicals for the prevention and treatment of pancreatic cancer: Current progress and future prospects

Pancreatic cancer is the third leading cause of cancer-related deaths in the United States, owing to its aggressive nature and suboptimal treatment options, emphasizing the need for novel therapeutic approaches. Emerging studies have exhibited promising results regarding the therapeutic utility of plant-derived compounds (phytochemicals) in pancreatic cancer. The purpose of this review is to evaluate the potential of phytochemicals in the treatment and prevention of pancreatic cancer. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses was applied to collect articles for this review. Scholarly databases, including PubMed, Scopus and ScienceDirect, were queried for relevant studies using the following keywords: phytochemicals, phenolics, terpenoids, alkaloids, sulfur-containing compounds, in vitro, in vivo, clinical studies, pancreatic cancer, tumour, treatment and prevention. Aggregate results pooled from qualified studies indicate phytochemicals can inhibit pancreatic cancer cell growth or decrease tumour size and volume in animal models. These effects have been attributed to various mechanisms, such as increasing proapoptotic factors, decreasing antiapoptotic factors, or inducing cell death and cell cycle arrest. Notable signalling pathways modulated by phytochemicals include the rat sarcoma/mitogen activated protein kinase, wingless-related integration site/β-catenin and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signal transduction pathways. Clinically, phytochemicals have been found to increase survival while being well-tolerated and safe, though research is scarce. While these promising results have produced great interest in this field, further in-depth studies are required to characterize the anticancer activities of phytochemicals before they can be utilized to prevent or treat pancreatic cancer in clinical practice.

"Double-edged sword" effect of reactive oxygen species (ROS) in tumor development and carcinogenesis

Reactive oxygen species (ROS) are small reactive molecules produced by cellular metabolism and regulate various physiological and pathological functions. Many studies have shown that ROS plays an essential role in the proliferation and inhibition of tumor cells. Different concentrations of ROS can have a "double-edged sword" effect on the occurrence and development of tumors. A certain concentration of ROS can activate growth-promoting signals, enhance the proliferation and invasion of tumor cells, and cause damage to biomacromolecules such as proteins and nucleic acids. However, ROS can enhance the body's antitumor signal at higher levels by initiating oxidative stress-induced apoptosis and autophagy in tumor cells. This review analyzes ROS's unique bidirectional regulation mechanism on tumor cells, focusing on the key signaling pathways and regulatory factors that ROS affect the occurrence and development of tumors and providing ideas for an in-depth understanding of the mechanism of ROS action and its clinical application.

Specificity Proteins (Sp) and Cancer

The specificity protein (Sp) transcription factors (TFs) Sp1, Sp2, Sp3 and Sp4 exhibit structural and functional similarities in cancer cells and extensive studies of Sp1 show that it is a negative prognostic factor for patients with multiple tumor types. In this review, the role of Sp1, Sp3 and Sp4 in the development of cancer and their regulation of pro-oncogenic factors and pathways is reviewed. In addition, interactions with non-coding RNAs and the development of agents that target Sp transcription factors are also discussed. Studies on normal cell transformation into cancer cell lines show that this transformation process is accompanied by increased levels of Sp1 in most cell models, and in the transformation of muscle cells into rhabdomyosarcoma, both Sp1 and Sp3, but not Sp4, are increased. The pro-oncogenic functions of Sp1, Sp3 and Sp4 in cancer cell lines were studied in knockdown studies where silencing of each individual Sp TF decreased cancer growth, invasion and induced apoptosis. Silencing of an individual Sp TF was not compensated for by the other two and it was concluded that Sp1, Sp3 and Sp4 are examples of non-oncogene addicted genes. This conclusion was strengthened by the results of Sp TF interactions with non-coding microRNAs and long non-coding RNAs where Sp1 contributed to pro-oncogenic functions of Sp/non-coding RNAs. There are now many examples of anticancer agents and pharmaceuticals that induce downregulation/degradation of Sp1, Sp3 and Sp4, yet clinical applications of drugs specifically targeting Sp TFs are not being used. The application of agents targeting Sp TFs in combination therapies should be considered for their potential to enhance treatment efficacy and decrease toxic side effects.

Glucotropaeolin Promotes Apoptosis by Calcium Dysregulation and Attenuates Cell Migration with FOXM1 Suppression in Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) has naturally aggressive characteristics including postoperative recurrence, resistance to conventional treatment, and metastasis. Surgical resection with chemotherapeutic agents has been conducted as the major treatment for PDAC. However, surgical treatment is ineffective in the case of advanced cancer, and conventional adjuvant chemotherapy, including gemcitabine and 5-fluorouracil, show low effectiveness due to the high drug resistance of PDAC to this type of treatment. Therefore, the development of innovative therapeutic drugs is crucial to solving the present limitation of conventional drugs. Glucotropaeolin (GT) is a glucosinolate that can be isolated from the Brassicaceae family. GT has exhibited a growth-inhibitory effect against liver and colon cancer cells; however, there is no study regarding the anticancer effect of GT on PDAC. In our study, we determined the antiproliferative effect of GT in PANC-1 and MIA PaCa-2, representative of PDAC. We revealed the intracellular mechanisms underlying the anticancer effect of GT with respect to cell viability, reactive oxygen species (ROS) accumulation, alteration of mitochondrial membrane potential (MMP), calcium dysregulation, cell migration, and the induction of apoptosis. Moreover, GT regulated the signaling pathways related to anticancer in PDAC cells. Finally, the silencing of the forkhead box protein M, a key factor regulating PDAC progression, contributes to the anticancer property of GT in terms of the induction of apoptosis and cell migration. Therefore, GT may be a potential therapeutic drug against PDAC.

Hydrogen Sulfide Biology and Its Role in Cancer

Hydrogen sulfide (H2S) is an endogenous biologically active gas produced in mammalian tissues. It plays a very critical role in many pathophysiological processes in the body. It can be endogenously produced through many enzymes analogous to the cysteine family, while the exogenous source may involve inorganic sulfide salts. H2S has recently been well investigated with regard to the onset of various carcinogenic diseases such as lung, breast, ovaries, colon cancer, and neurodegenerative disorders. H2S is considered an oncogenic gas, and a potential therapeutic target for treating and diagnosing cancers, due to its role in mediating the development of tumorigenesis. Here in this review, an in-detail up-to-date explanation of the potential role of H2S in different malignancies has been reported. The study summarizes the synthesis of H2S, its roles, signaling routes, expressions, and H2S release in various malignancies. Considering the critical importance of this active biological molecule, we believe this review in this esteemed journal will highlight the oncogenic role of H2S in the scientific community.

Peroxidase from foxtail millet bran exerts anti-colorectal cancer activity via targeting cell-surface GRP78 to inactivate STAT3 pathway

Molecular targeted therapy has become an emerging promising strategy in cancer treatment, and screening the agents targeting at cancer cell specific targets is very desirable for cancer treatment. Our previous study firstly found that a secretory peroxidase of class III derived from foxtail millet bran (FMBP) exhibited excellent targeting anti-colorectal cancer (CRC) activity in vivo and in vitro, whereas its underlying target remains unclear. The highlight of present study focuses on the finding that cell surface glucose-regulated protein 78 (csGRP78) abnormally located on CRC is positively correlated with the anti-CRC effects of FMBP, indicating it serves as a potential target of FMBP against CRC. Further, we demonstrated that the combination of FMBP with the nucleotide binding domain (NBD) of csGRP78 interfered with the downstream activation of signal transducer and activator of transcription 3 (STAT3) in CRC cells, thus promoting the intracellular accumulation of reactive oxygen species (ROS) and cell grown inhibition. These phenomena were further confirmed in nude mice tumor model. Collectively, our study highlights csGRP78 acts as an underlying target of FMBP against CRC, uncovering the clinical potential of FMBP as a targeted agent for CRC in the future.

Caspase-Mediated Cleavage of the Transcription Factor Sp3: Possible Relevance to Cancer and the Lytic Cycle of Kaposi's Sarcoma-Associated Herpesvirus

The open reading frame 50 (ORF50) protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the master regulator essential for initiating the viral lytic cycle. Previously, we have demonstrated that the ORF50 protein can cooperate with Sp3 to synergistically activate a set of viral and cellular gene promoters through highly conserved ORF50-responsive elements that harbor a Sp3-binding motif. Herein, we show that Sp3 undergoes proteolytic cleavage during the viral lytic cycle, and the cleavage of Sp3 is dependent on caspase activation. Since similar cleavage patterns of Sp3 could be detected in both KSHV-positive and KSHV-negative lymphoma cells undergoing apoptosis, the proteolytic cleavage of Sp3 could be a common event during apoptosis. Mutational analysis identifies 12 caspase cleavage sites in Sp3, which are situated at the aspartate (D) positions D17, D19, D180, D273, D275, D293, D304 (or D307), D326, D344, D530, D543, and D565. Importantly, we noticed that three stable Sp3 C-terminal fragments generated through cleavage at D530, D543, or D565 encompass an intact DNA-binding domain. Like the full-length Sp3, the C-terminal fragments of Sp3 could still retain the ability to cooperate with ORF50 protein to activate specific viral and cellular gene promoters synergistically. Collectively, our findings suggest that despite the proteolytic cleavage of Sp3 under apoptotic conditions, the resultant Sp3 fragments may retain biological activities important for the viral lytic cycle or for cellular apoptosis. IMPORTANCE The ORF50 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the key viral protein that controls the switch from latency to lytic reactivation. It is a potent transactivator that can activate target gene promoters via interacting with other cellular DNA-binding transcription factors, such as Sp3. In this report, we show that Sp3 is proteolytically cleaved during the viral lytic cycle, and up to 12 caspase cleavage sites are identified in Sp3. Despite the proteolytic cleavage of Sp3, several resulting C-terminal fragments that have intact zinc-finger DNA-binding domains still retain substantial influence in the synergy with ORF50 to activate specific gene promoters. Overall, our studies elucidate the caspase-mediated cleavage of Sp3 and uncover how ORF50 utilizes the cleavage fragments of Sp3 to transactivate specific viral and cellular gene promoters.

Inhibition of Growth of Colon Tumors and Proliferation of HT-29 Cells by Warburgia ugandensis Extract through Mediating G0/G1 Cell Cycle Arrest, Cell Apoptosis, and Intracellular ROS Generation

Warburgia ugandensis Sprague (W. ugandensis), widely distributed in Africa, is a traditional medicinal plant used for the treatment of various diseases including cancer. We intended to evaluate the anticolorectal cancer (CRC) activities of the crude extract from W. ugandensis (WUD) and reveal the underlying molecular mechanisms of its action. We found that WUD inhibited the proliferation of HT-29 and HCT116 cells in a time- and dose-dependent manner and induced intracellular ROS generation. The inhibitory effect of WUD on the proliferation of HT-29 and HCT116 cells could be attenuated by NAC (a ROS scavenger) in a dose-dependent manner. WUD induced G₀/G₁ phase arrest, down-regulated the protein expression of Cyclin D1 via ROS accumulation in HT-29 cells. In search of the molecular mechanism involved in WUD-induced Cyclin D1 down-regulation, it was found that WUD can suppress PI3K/Akt/GSK3β signaling pathway in HT-29 cells. Next, it was found that WUD also activated apoptosis, poly-ADP ribose polymerase 1 (PARP1) cleavage and down-regulated pro-caspase 3 in HT-29 and HCT116 cells. Besides, WUD decreased the growth of colon tumors in vivo in the xenograft mouse model. We demonstrated for the first time that ROS and their modulation in the corresponding intracellular signaling could play a significant role in the potential activity of WUD against CRC cells.

Natural Products in the Prevention of Metabolic Diseases: Lessons Learned from the 20th KAST Frontier Scientists Workshop

The incidence of metabolic and chronic diseases including cancer, obesity, inflammation-related diseases sharply increased in the 21st century. Major underlying causes for these diseases are inflammation and oxidative stress. Accordingly, natural products and their bioactive components are obvious therapeutic agents for these diseases, given their antioxidant and anti-inflammatory properties. Research in this area has been significantly expanded to include chemical identification of these compounds using advanced analytical techniques, determining their mechanism of action, food fortification and supplement development, and enhancing their bioavailability and bioactivity using nanotechnology. These timely topics were discussed at the 20th Frontier Scientists Workshop sponsored by the Korean Academy of Science and Technology, held at the University of Hawaii at Manoa on 23 November 2019. Scientists from South Korea and the U.S. shared their recent research under the overarching theme of Bioactive Compounds, Nanoparticles, and Disease Prevention. This review summarizes presentations at the workshop to provide current knowledge of the role of natural products in the prevention and treatment of metabolic diseases.

Anticancer activities of dietary benzyl isothiocyanate: A comprehensive review

Benzyl isothiocyanate (BITC) is one of the common isothiocyanates found in cruciferous vegetables such as broccoli, cabbage or watercress. Preclinical studies report of its effectiveness in the prevention and treatment against several cancers. This review aims to report and discuss findings on anticancer activities of BITC and its modes of action against 14 types of cancer. A literature search was conducted using the keywords "BITC" and "anticancer" from PubMed, Google Scholar and CINAHL Plus to obtain relevant research articles. This review highlights the anticancer efficacy of BITC through modulation of various signaling pathways involved in apoptosis, cell proliferation, cell cycle arrest, metastasis, angiogenesis, autophagy and the effects of BITC in combination with other drugs. With the available pharmacology evidence, we conclude that further studies are needed to validate its effectiveness in humans for further development and translation into prophylaxis or therapy by promoting optimal therapeutic effects and minimizing toxicity in cancer treatment.

New possible silver lining for pancreatic cancer therapy: Hydrogen sulfide and its donors

As one of the most lethal diseases, pancreatic cancer shows a dismal overall prognosis and high resistance to most treatment modalities. Furthermore, pancreatic cancer escapes early detection during the curable period because early symptoms rarely emerge and specific markers for this disease have not been found. Although combinations of new drugs, multimodal therapies, and adjuvants prolong survival, most patients still relapse after surgery and eventually die. Consequently, the search for more effective treatments for pancreatic cancer is highly relevant and justified. As a newly re-discovered mediator of gasotransmission, hydrogen sulfide (H₂S) undertakes essential functions, encompassing various signaling complexes that occupy key processes in human biology. Accumulating evidence indicates that H₂S exhibits bimodal modulation of cancer development. Thus, endogenous or low levels of exogenous H₂S are thought to promote cancer, whereas high doses of exogenous H₂S suppress tumor proliferation. Similarly, inhibition of endogenous H₂S production also suppresses tumor proliferation. Accordingly, H₂S biosynthesis inhibitors and H₂S supplementation (H₂S donors) are two distinct strategies for the treatment of cancer. Unfortunately, modulation of endogenous H₂S on pancreatic cancer has not been studied so far. However, H₂S donors and their derivatives have been extensively studied as potential therapeutic agents for pancreatic cancer therapy by inhibiting cell proliferation, inducing apoptosis, arresting cell cycle, and suppressing invasion and migration through exploiting multiple signaling pathways. As far as we know, there is no review of the effects of H₂S donors on pancreatic cancer. Based on these concerns, the therapeutic effects of some H₂S donors and NO–H₂S dual donors on pancreatic cancer were summarized in this paper. Exogenous H₂S donors may be promising compounds for pancreatic cancer treatment.

Curcumin and cancer biology: Focusing regulatory effects in different signalling pathways

Cancer is the second-leading cause of death worldwide. Till date, many such effective treatments are available, for example chemotherapy, surgery, and radiation therapy, but there are severe associated side effects, such as increased infection risk, constipation, hair loss, anaemia, among others. Thus, the need for effective therapeutic strategies and screening methodology arises. Researchers around the world are increasingly trying to discover anticancer therapies with as few side effects as possible and many are now focusing on phytochemicals, like curcumin. Curcumin is a bright yellow substance isolated from the plant rhizomes of Curcuma longa L. To this molecule a high therapeutic benefit has been underlined, being able to alter the development of cancer by different mechanisms, such as regulating multiple microRNA expression, modifying a series of signalling pathways, that is, Akt, Bcl-2, PTEN, p53, Notch, and Erbb. Another major pathway that curcumin targets is the matrix metalloproteinase (MMP) gene expression. In fact, MMPs are responsible for the degradation of the cell-extracellular matrix, which can lead to the diseased condition and many different pathways contribute to its activity, such as JAK/STAT, NF-κB, MAPK/ERK, COX-2, ROS, TGF-β, among others. In this review, we have attempted to describe the curcumin regulatory effect on different cell signalling pathways involved in the progression of different types of cancers.

Arsenic suppresses GDF1 expression via ROS-dependent downregulation of specificity protein 1

Inorganic arsenic, an environmental contaminant, has adverse health outcomes. Our previous studies showed that arsenic causes abnormal cardiac development in zebrafish embryos by downregulating Dvr1/GDF1 expression and that folic acid protects against these effects. However, the mechanism by which arsenic represses Dvr1/GDF1 expression remains unknown. Herein, we demonstrate that specificity protein 1 (Sp1) acts as a transcriptional activator of GDF1. Arsenic treatment downregulated Sp1 at both the mRNA and protein level and its downstream targets GDF1 and SIRT1. Chromatin immunoprecipitation analysis showed that the occupancy of Sp1 on the GDF1 or SIRT1 promoter was significantly reduced in response to arsenite. Further investigation showed that Sp1 overexpression inhibited the arsenic-mediated decrease in GDF1 and SIRT1, while Sp1 knockdown had the opposite effect. We found that expression of the oxidative adaptor p66shc was inversely related to that of SIRT1 and that the binding of SIRT1 to the p66shc promoter was sharply attenuated by arsenite treatment. SIRT1 overexpression attenuated p66shc expression but enhanced GDF1 protein expression, while SIRT1 depletion exerted the opposite effect. Both the antioxidants N-acetylcysteine and folic acid reversed the arsenic-mediated repression of Sp1, GDF1 and SIRT1. Moreover, wild-type p66shc overexpression enhanced the arsenic-mediated repression of Sp1, GDF1 and SIRT1, which was accompanied by an increase in intracellular reactive oxygen species (ROS) levels, while both overexpression of a dominant negative p66shcSer36Ala mutant and deficiency in p66shc reversed these effects. Taken together, our results revealed that arsenic suppresses GDF1 expression via the ROS-dependent downregulation of the Sp1/SIRT1 axis, which forms a negative feedback loop with p66shc to regulate oxidative stress. Our findings reveal a novel molecular mechanism underlying arsenic toxicity and provide new insight into the protective effect of folic acid in arsenic-mediated toxicity.

Tetraarsenic hexoxide enhances generation of mitochondrial ROS to promote pyroptosis by inducing the activation of caspase-3/GSDME in triple-negative breast cancer cells

Although tetraarsenic hexoxide is known to exert an anti-tumor effect by inducing apoptosis in various cancer cells, its effect on other forms of regulated cell death remains unclear. Here, we show that tetraarsenic hexoxide induces the pyroptotic cell death through activation of mitochondrial reactive oxygen species (ROS)-mediated caspase-3/gasdermin E (GSDME) pathway, thereby suppressing tumor growth and metastasis of triple-negative breast cancer (TNBC) cells. Interestingly, tetraarsenic hexoxide-treated TNBC cells exhibited specific pyroptotic characteristics, including cell swelling, balloon-like bubbling, and LDH releases through pore formation in the plasma membrane, eventually suppressing tumor formation and lung metastasis of TNBC cells. Mechanistically, tetraarsenic hexoxide markedly enhanced the production of mitochondrial ROS by inhibiting phosphorylation of mitochondrial STAT3, subsequently inducing caspase-3-dependent cleavage of GSDME, which consequently promoted pyroptotic cell death in TNBC cells. Collectively, our findings highlight tetraarsenic hexoxide-induced pyroptosis as a new therapeutic strategy that may inhibit cancer progression of TNBC cells.

Dietary isothiocyanates inhibit cancer progression by modulation of epigenome

Cell cycle, growth, survival and metabolism are tightly regulated together and failure in cellular regulation leads to carcinogenesis. Several signaling pathways like the PI3K, WNT, MAPK and NFKb pathway exhibit aberrations in cancer and help achieve hallmark capabilities. Clinical research and in vitro studies have highlighted the role of epigenetic alterations in cancer onset and development. Altered gene expression patterns enabled by changes in DNA methylation, histone modifications and RNA processing have proven roles in cancer hallmark acquisition. The reversible nature of epigenetic processes offers robust therapeutic targets. Dietary bioactive compounds offer a vast compendium of effective therapeutic moieties. Isothiocyanates (ITCs) sourced from cruciferous vegetables demonstrate anti-proliferative, pro-apoptotic, anti-inflammatory, anti-migratory and anti-angiogenic effect against several cancers. ITCs also modulate the redox environment, modulate signaling pathways including PI3K, MAPK, WNT, and NFkB. They also modulate the epigenetic machinery by regulating the expression and activity of DNA methyltransferases, histone modifiers and miRNA. This further enhances their transcriptional modulation of key cellular regulators. In this review, we comprehensively assess the impact of ITCs such as sulforaphane, phenethyl isothiocyanate, benzyl isothiocyanate and allyl isothiocyanate on cancer and document their effect on various molecular targets. Overall, this will facilitate consolidation of the current understanding of the anti-cancer and epigenetic modulatory potential of these compounds and recognize the gaps in literature. Further, we discuss avenues of future research to develop these compounds as potential therapeutic entities.

Mechanisms Underlying Biological Effects of Cruciferous Glucosinolate-Derived Isothiocyanates/Indoles: A Focus on Metabolic Syndrome

An inverse correlation between vegetable consumption and the incidence of cancer has long been described. This protective effect is stronger when cruciferous vegetables are specifically consumed. The beneficial properties of vegetables are attributed to their bioactive components like fiber, antioxidants vitamins, antioxidants, minerals, and phenolic compounds. Cruciferous vegetables contain all these molecules; however, what makes them different are their sulfurous components, called glucosinolates, responsible for their special smell and taste. Glucosinolates are inactive biologically in the organism but are hydrolyzed by the enzyme myrosinase released as a result of chewing, leading to the formation of active derivatives such as isothiocyanates and indoles. A considerable number of in vitro and in vivo studies have reported that isothiocyanates and indoles elicit chemopreventive potency through multiple mechanisms that include modulation of phases I and II detoxification pathway enzymes, regulation of cell cycle arrest, and control of cell growth, induction of apoptosis, antioxidant activity, anti-angiogenic effects, and epigenetic regulation. Nuclear erythroid 2-related factor 2 (Nrf2) and Nuclear factor-κB (NF-κB) are key and central regulators in all these processes with a main role in oxidative stress and inflammation control. It has been described that isothiocyanates and indoles regulate their activity directly and indirectly. Today, the metabolic syndrome (central obesity, insulin resistance, hyperlipidemia, and hypertension) is responsible for a majority of deaths worldwide. All components of metabolic syndrome are characterized by chronic inflammation with deregulation of the PI3K/AKT/mTOR, MAPK/EKR/JNK, Nrf2, and NF-κB signaling pathways. The effects of GLSs derivatives controlling these pathways have been widely described in relation to cancer. Changes in food consumption patterns observed in the last decades to higher consumption of ultra-processed foods, with elevation in simple sugar and saturated fat contents and lower consumption of vegetables and fruits have been directly correlated with metabolic syndrome prevalence. In this review, it is summarized the knowledge regarding the mechanisms by which cruciferous glucosinolate derivatives (isothiocyanates and indoles) directly and indirectly regulate these pathways. However, the review places a special focus on the knowledge of the effects of glucosinolates derivatives in metabolic syndrome, since this has not been reviewed before.

Strategies to Modulate MicroRNA Functions for the Treatment of Cancer or Organ Injury

Cancer and organ injury-such as that occurring in the perioperative period, including acute lung injury, myocardial infarction, and acute gut injury-are among the leading causes of death in the United States and impose a significant impact on quality of life. MicroRNAs (miRNAs) have been studied extensively during the last two decades for their role as regulators of gene expression, their translational application as diagnostic markers, and their potential as therapeutic targets for disease treatment. Despite promising preclinical outcomes implicating miRNA targets in disease treatment, only a few miRNAs have reached clinical trials. This likely relates to difficulties in the delivery of miRNA drugs to their targets to achieve efficient inhibition or overexpression. Therefore, understanding how to efficiently deliver miRNAs into diseased tissues and specific cell types in patients is critical. This review summarizes current knowledge on various approaches to deliver therapeutic miRNAs or miRNA inhibitors and highlights current progress in miRNA-based disease therapy that has reached clinical trials. Based on ongoing advances in miRNA delivery, we believe that additional therapeutic approaches to modulate miRNA function will soon enter routine medical treatment of human disease, particularly for cancer or perioperative organ injury. SIGNIFICANCE STATEMENT: MicroRNAs have been studied extensively during the last two decades in cancer and organ injury, including acute lung injury, myocardial infarction, and acute gut injury, for their regulation of gene expression, application as diagnostic markers, and therapeutic potentials. In this review, we specifically emphasize the pros and cons of different delivery approaches to modulate microRNAs, as well as the most recent exciting progress in the field of therapeutic targeting of microRNAs for disease treatment in patients.

Benzyl Isothiocyanate Induces Apoptosis via Reactive Oxygen Species-Initiated Mitochondrial Dysfunction and DR4 and DR5 Death Receptor Activation in Gastric Adenocarcinoma Cells

Benzyl isothiocyanate (BITC) is known to inhibit the metastasis of gastric cancer cells but further studies are needed to confirm its chemotherapeutic potential against gastric cancer. In this study, we observed cell shrinkage and morphological changes in one of the gastric adenocarcinoma cell lines, the AGS cells, after BITC treatment. We performed 3-(4,5-dimethyl-2-thiazolyl)-2,5- diphenyl-2H-tetrazolium bromide (MTT) assay, a cell viability assay, and found that BITC decreased AGS cell viability. Reactive oxygen species (ROS) analyses using 2',7'-dichlorofluorescin diacetate (DCFDA) revealed that BITC-induced cell death involved intracellular ROS production, which resulted in mitochondrial dysfunction. Additionally, cell viability was partially restored when BITC-treated AGS cells were preincubated with glutathione (GSH). Western blotting indicated that BITC regulated the expressions of the mitochondria-mediated apoptosis signaling molecules, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and cytochrome c (Cyt c). In addition, BITC increased death receptor DR5 expression, and activated the cysteine-aspartic proteases (caspases) cascade. Overall, our results showed that BITC triggers apoptosis in AGS cells via the apoptotic pathways involved in ROS-promoted mitochondrial dysfunction and death receptor activation.

Bioactivation of Napabucasin Triggers Reactive Oxygen Species-Mediated Cancer Cell Death

PURPOSE

Napabucasin (2-acetylfuro-1,4-naphthoquinone or BBI-608) is a small molecule currently being clinically evaluated in various cancer types. It has mostly been recognized for its ability to inhibit STAT3 signaling. However, based on its chemical structure, we hypothesized that napabucasin is a substrate for intracellular oxidoreductases and therefore may exert its anticancer effect through redox cycling, resulting in reactive oxygen species (ROS) production and cell death.

EXPERIMENTAL DESIGN

Binding of napabucasin to NAD(P)H:quinone oxidoreductase-1 (NQO1), and other oxidoreductases, was measured. Pancreatic cancer cell lines were treated with napabucasin, and cell survival, ROS generation, DNA damage, transcriptomic changes, and alterations in STAT3 activation were assayed in vitro and in vivo. Genetic knockout or pharmacologic inhibition with dicoumarol was used to evaluate the dependency on NQO1.

RESULTS

Napabucasin was found to bind with high affinity to NQO1 and to a lesser degree to cytochrome P450 oxidoreductase (POR). Treatment resulted in marked induction of ROS and DNA damage with an NQO1- and ROS-dependent decrease in STAT3 phosphorylation. Differential cytotoxic effects were observed, where NQO1-expressing cells generating cytotoxic levels of ROS at low napabucasin concentrations were more sensitive. Cells with low or no baseline NQO1 expression also produced ROS in response to napabucasin, albeit to a lesser extent, through the one-electron reductase POR.

CONCLUSIONS

Napabucasin is bioactivated by NQO1, and to a lesser degree by POR, resulting in futile redox cycling and ROS generation. The increased ROS levels result in DNA damage and multiple intracellular changes, one of which is a reduction in STAT3 phosphorylation.

Benzyl isothiocyanate suppresses development and metastasis of murine mammary carcinoma by regulating the Wnt/β‑catenin pathway

Benzyl isothiocyanate (BITC) has been reported to exhibit antitumor properties in various cancer types; however, the underlying mechanisms of its action remain unclear. In the present study, the efficacy of BITC on murine mammary carcinoma cells was evaluated in vitro and in vivo, revealing a potential mechanism for its action. In vivo bioluminescence imaging indicated dynamic inhibition of murine mammary carcinoma cell growth and metastasis by BITC. A terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay demonstrated that BITC also induced apoptosis. BITC further exhibited antitumorigenic activity in 4T1-Luc cells in vitro via the inhibition of cell proliferation, induction of apoptosis and cell cycle arrest, and inhibition of cell migration and invasion. Furthermore, the activity of key molecules of the adenomatous polyposis coli (APC)/β-catenin complex was altered following treatment with BITC, which suggested a potential role for the APC/β-catenin complex in the BITC-mediated induction of apoptosis and inhibition of metastasis in murine mammary carcinoma. BITC upregulated the activity of glycogen synthase kinase-3β and APC proteins, whereas it downregulated β-catenin expression. The inhibition of metastasis was accompanied with the downregulation of vimentin and upregulation of E-cadherin. Conversely, BITC did not exhibit toxicity or side effects in the normal mammary epithelial cell line MCF-10A. The present study indicated that BITC exhibited anticancer properties due to the induction of breast cancer cell apoptosis and inhibition of breast cancer cell metastasis mediated by the Wnt/β-catenin signaling pathway.

ROS-Mediated Cancer Cell Killing through Dietary Phytochemicals

Reactive oxygen species (ROS) promote carcinogenesis by inducing genetic mutations, activating oncogenes, and raising oxidative stress, which all influence cell proliferation, survival, and apoptosis. Cancer cells display redox imbalance due to increased ROS level compared to normal cells. This unique feature in cancer cells may, therefore, be exploited for targeted therapy. Over the past few decades, natural compounds have attracted attention as potential cancer therapies because of their ability to maintain cellular redox homeostasis with minimal toxicity. Preclinical studies show that bioactive dietary polyphenols exert antitumor effects by inducing ROS-mediated cytotoxicity in cancer cells. These bioactive compounds also regulate cell proliferation, survival, and apoptotic and antiapoptotic signalling pathways. In this review, we discuss (i) how ROS is generated and (ii) regulated and (iii) the cell signalling pathways affected by ROS. We also discuss (iv) the various dietary phytochemicals that have been implicated to have cancer therapeutic effects through their ROS-related functions.

The Role of Isothiocyanates as Cancer Chemo-Preventive, Chemo-Therapeutic and Anti-Melanoma Agents

Many studies have shown evidence in support of the beneficial effects of phytochemicals in preventing chronic diseases, including cancer. Among such phytochemicals, sulphur-containing compounds (e.g., isothiocyanates (ITCs)) have raised scientific interest by exerting unique chemo-preventive properties against cancer pathogenesis. ITCs are the major biologically active compounds capable of mediating the anticancer effect of cruciferous vegetables. Recently, many studies have shown that a higher intake of cruciferous vegetables is associated with reduced risk of developing various forms of cancers primarily due to a plurality of effects, including (i) metabolic activation and detoxification, (ii) inflammation, (iii) angiogenesis, (iv) metastasis and (v) regulation of the epigenetic machinery. In the context of human malignant melanoma, a number of studies suggest that ITCs can cause cell cycle growth arrest and also induce apoptosis in human malignant melanoma cells. On such basis, ITCs could serve as promising chemo-therapeutic agents that could be used in the clinical setting to potentiate the efficacy of existing therapies.

Benzyl isothiocyanate inhibits invasion and induces apoptosis via reducing S100A4 expression and increases PUMA expression in oral squamous cell carcinoma cells

Benzyl isothiocyanate (BITC) has been shown to inhibit invasion and induce apoptosis of various types of cancer. However, its role on human oral squamous cell carcinoma (OSCC) cells is still not well elucidated. In the present study, we investigated the effect of BITC on apoptosis and invasion of SCC9 cells, and its underlying mechanisms in vitro and in vivo. SCC9 cells were exposed to BITC (5 and 25 μM) for 24 and 48 h. Cell growth, apoptosis, invasion, and migration were detected in vitro by MTT, FITC-conjugated annexin V/propidium iodide staining followed by flow cytometry, Matrigel-coated semi-permeable modified Boyden, and wound-healing assay. S100A4, PUMA, and MMP-9 expressions were detected to investigate its mechanisms. Xenotransplantation experiments were used to investigate the role of BITC on tumor growth and lung metastasis. BITC inhibited cell viability and induced cell apoptosis in a dose- and time-dependent manner through upregulation of PUMA signals. BITC inhibited cell invasion and migration by downregulation of S100A4 dependent MMP-9 signals. The ip administration of BITC reduced tumor growth but not lung metastasis of SCC9 cells subcutaneously implanted in nude mice. BITC treatment activated pro-apoptotic PUMA and inhibited S100A4-dependent MMP-9 signals, resulting in the inhibition of cell growth and invasion in cultured and xenografted SCC9 cells. Thereby, BITC is a potential therapeutic approach for OSCC.

Genome-wide analysis reveals miR-3184-5p and miR-181c-3p as a critical regulator for adipocytes-associated breast cancer

Obesity is considered as an independent risk factor for breast cancer (BCa) and plays a major role in the breast tumor microenvironment. The etiology and mechanisms by which obesity contributes to BCa development is not yet understood. Herein, we show that in vitro coculture of BCa cells with mature adipocytes (MA-BCa) increased proliferation, migration, and invasive phenotype of BCa cells. MA-BCa coculture led to increased production of proinflammatory cytokines and chemokines. To identify microRNAs (miRNAs) in BCa cells that are modulated by the presence of adipocytes, we used small RNA sequencing analysis. Sequencing data revealed that 98 miRNAs were differentially expressed in MA-BCa. Among them, miR-3184-5p and miR-181c-3p were found to be the most upregulated and downregulated miRNAs, and direct targets are FOXP4 and PPARα, respectively. In vitro functional assays using a combination of miR-3184-5p inhibitor and miR-181c-3p mimic synergistically decreased adipocytes-induced cell proliferation and invasive capacity of BCa cells. Gene Set Enrichment analysis indicated that transcription factors were highly enriched followed by protein kinases, oncogene, and protein regulators in MA-BCa. GeneGo Metacore pathway analysis uncovered "NOTCH-induced EMT pathway" was found to be the most abundant in MA-BCa. Consistently, epithelial-mesenchymal transition-associated markers were also increased in MA-BCa. The disease enrichment analysis of the predict target genes revealed that diabetes mellitus was significantly affected disease in MA-BCa. Taken together, our data suggest that miRNA-based regulatory mechanism associated with deregulation of pathways and biological functions orchestrated by adipocytes-secreted factors might drive the BCa progression and metastasis in obese patients.

MTA2-mediated inhibition of PTEN leads to pancreatic ductal adenocarcinoma carcinogenicity

Metastasis-associated protein 2 (MTA2) is a core subunit of the nucleosome remodeling and deacetylating (NuRD) complex and functions by mediating chromatin remodeling and gene silencing. However, its biological actions and clinical significance in pancreatic ductal adenocarcinoma (PDAC) remain elusive. The aim of this study was to explore the function and regulation mechanism of MTA2 in PDAC. As shown in GEO, ICGC, and TCGA databases, a higher expression of MTA2 was noticed in the PDAC tissues than in the normal pancreatic tissues. Moreover, a higher expression level of MTA2 was associated with a shorter overall survival time in these public PDAC databases. We further investigated the underlying mechanisms of these observations by using a chromatin immunoprecipitation (ChIP)-based deep sequencing, luciferase reporter, and quantitative ChIP assays. We identified the repressive binding of MTA2 to the promoter of phosphatase and tensin homolog (PTEN). We also found that Snail recruited MTA2 and HDAC1 to suppress PTEN expression. Ectopic expression and knockdown of MTA2 were performed to evaluate the effects of this gene on PDAC cell proliferation, migration, and invasion. Using CCK-8, colony formation and transwell assays, and a xenograft tumor model, we revealed that MTA2 promoted PDAC cell proliferation, migration, and invasion in vitro and PDAC tumor growth in vivo by downregulation of PTEN. In benzyl isothiocyanate (BITC)-treated MIA Paca-2 cells and PANC-1 cells, MTA2 level decreased in a dose- and time-dependent manner with concomitant upregulation of PTEN level and downregulation of phosphorylated PI3K and AKT levels, providing evidence of the involvement of MTA2 and PTEN in the regulation of the PI3K/AKT pathway in BITC-mediated PDAC suppression. Collectively, these findings uncover a novel role for MTA2 in the regulation of PDAC progression and help to elucidate the mechanisms involved in this process.

Metformin-induced anticancer activities: recent insights

Metformin is a widely used antidiabetic drug, and there is evidence among diabetic patients that metformin is a chemopreventive agent against multiple cancers. There is also evidence in human studies that metformin is a cancer chemotherapeutic agent, and several clinical trials that use metformin alone or in combination with other drugs are ongoing. In vivo and in vitro cancer cell culture studies demonstrate that metformin induces both AMPK-dependent and AMPK-independent genes/pathways that result in inhibition of cancer cell growth and migration and induction of apoptosis. The effects of metformin in cancer cells resemble the patterns observed after treatment with drugs that downregulate specificity protein 1 (Sp1), Sp3 and Sp4 or by knockdown of Sp1, Sp3 and Sp4 by RNA interference. Studies in pancreatic cancer cells clearly demonstrate that metformin decreases expression of Sp1, Sp3, Sp4 and pro-oncogenic Sp-regulated genes, demonstrating that one of the underlying mechanisms of action of metformin as an anticancer agent involves targeting of Sp transcription factors. These observations are consistent with metformin-mediated effects on genes/pathways in many other tumor types.

P4HB knockdown induces human HT29 colon cancer cell apoptosis through the generation of reactive oxygen species and inactivation of STAT3 signaling

Colon cancer is the second most lethal malignancy worldwide. A better understanding of colon cancer at the molecular level may increase overall survival rates. Previous studies have indicated that prolyl 4-hydroxylase, β polypeptide (P4HB) is associated with tumorigenesis in colon cancer; however, its role and molecular mechanisms in colon cancer remain unclear. In the present study, the cellular responses to P4HB in human colon cancer cell lines were investigated by proliferation and apoptosis assays, western blotting, and immunohistochemistry. The results showed that expression of P4HB was higher in colon cancer tissues compared within adjacent normal tissues. P4HB knockdown increased the apoptosis of human HT29 cells. Furthermore, P4HB knockdown reduced the activation of signal transducer and activator of transcription 3 (STAT3) and promoted accumulation of reactive oxygen species (ROS). Inhibiting the accumulation of ROS abrogated the increased cell apoptosis induced by P4HB knockdown. Notably, decreased ROS levels effectively antagonized the effects of P4HB on STAT3 inactivation. In conclusion, these findings suggested that P4HB knockdown may induce HT29 human colon cancer cell apoptosis through the generation of ROS and inactivation of the STAT3 signaling pathway.

Anti-Carcinogenic Glucosinolates in Cruciferous Vegetables and Their Antagonistic Effects on Prevention of Cancers

Glucosinolates (GSL) are naturally occurring β-d-thioglucosides found across the cruciferous vegetables. Core structure formation and side-chain modifications lead to the synthesis of more than 200 types of GSLs in Brassicaceae. Isothiocyanates (ITCs) are chemoprotectives produced as the hydrolyzed product of GSLs by enzyme myrosinase. Benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC) and sulforaphane ([1-isothioyanato-4-(methyl-sulfinyl) butane], SFN) are potential ITCs with efficient therapeutic properties. Beneficial role of BITC, PEITC and SFN was widely studied against various cancers such as breast, brain, blood, bone, colon, gastric, liver, lung, oral, pancreatic, prostate and so forth. Nuclear factor-erythroid 2-related factor-2 (Nrf2) is a key transcription factor limits the tumor progression. Induction of ARE (antioxidant responsive element) and ROS (reactive oxygen species) mediated pathway by Nrf2 controls the activity of nuclear factor-kappaB (NF-κB). NF-κB has a double edged role in the immune system. NF-κB induced during inflammatory is essential for an acute immune process. Meanwhile, hyper activation of NF-κB transcription factors was witnessed in the tumor cells. Antagonistic activity of BITC, PEITC and SFN against cancer was related with the direct/indirect interaction with Nrf2 and NF-κB protein. All three ITCs able to disrupts Nrf2-Keap1 complex and translocate Nrf2 into the nucleus. BITC have the affinity to inhibit the NF-κB than SFN due to the presence of additional benzyl structure. This review will give the overview on chemo preventive of ITCs against several types of cancer cell lines. We have also discussed the molecular interaction(s) of the antagonistic effect of BITC, PEITC and SFN with Nrf2 and NF-κB to prevent cancer.

Reactive Oxygen and Nitrogen Species-Induced Protein Modifications: Implication in Carcinogenesis and Anticancer Therapy

Cancer is a complex disorder extremely dependent on its microenvironment and highly regulated by multiple intracellular and extracellular stimuli. Studies show that reactive oxygen and nitrogen species (RONS) play key roles in cancer initiation and progression. Accumulation of RONS caused by imbalance between RONS generation and activity of antioxidant system (AOS) has been observed in many cancer types. This leads to alterations in gene expression levels, signal transduction pathways, and protein quality control machinery, that is, processes that regulate cancer cell proliferation, migration, invasion, and apoptosis. This review focuses on the latest advancements evidencing that RONS-induced modifications of key redox-sensitive residues in regulatory proteins, that is, cysteine oxidation/S-sulfenylation/S-glutathionylation/S-nitrosylation and tyrosine nitration, represent important molecular mechanisms underlying carcinogenesis. The oxidative/nitrosative modifications cause alterations in activities of intracellular effectors of MAPK- and PI3K/Akt-mediated signaling pathways, transcription factors (Nrf2, AP-1, NFκB, STAT3, and p53), components of ubiquitin/proteasomal and autophagy/lysosomal protein degradation systems, molecular chaperones, and cytoskeletal proteins. Redox-sensitive proteins, RONS-generating enzymes, and AOS components can serve as targets for relevant anticancer drugs. Chemotherapeutic agents exert their action via RONS generation and induction of cancer cell apoptosis, while drug resistance associates with RONS-induced cancer cell survival; this is exploited in selective anticancer therapy strategies. Cancer Res; 78(21); 6040-7. ©2018 AACR.

Betulinic acid as apoptosis activator: Molecular mechanisms, mathematical modeling and chemical modifications

A natural product betulinic acid (BA) has gained a huge significance in the recent years for its strong cytotoxicity. Surprisingly, in spite of being an interesting cancer protecting agent on a variety of tumor cells, the normal cells and tissues are rarely affected by BA. Betulinic acid and analogues (BAs) generally exert through the mechanisms that provokes an event of direct cell death and bypass the resistance to normal chemotherapeutics. Although the major mechanism associated with its ability to induce direct cell death is mitochondrial apoptosis, there are several other mechanisms explored recently. Importantly, mathematical modeling of apoptosis has been an important tool to explore the precise mechanism involved in mitochondrial apoptosis. Thus, this review is an endeavor to sum up the molecular mechanisms underlying the action of BA and future directions to apply mathematical modeling technique to better understand the precise mechanism of BA-induced apoptosis. The last section of the review encompasses the plausible structural modifications and formulations to enhance the therapeutic efficacy of BA.

Benzyl isothiocyanate (BITC) triggers mitochondria-mediated apoptotic machinery in human cisplatin-resistant oral cancer CAR cells

Benzyl isothiocyanate (BITC), a component of dietary food, possesses a powerful anticancer activity. Previous studies have shown that BITC produces a large number of intracellular reactive oxygen species (ROS) and increases intracellular Ca²⁺ release from endoplasmic reticulum (ER), leading to the activation of the apoptotic mechanism in tumor cells. However, there is not much known regarding the inhibitory effect of BITC on cisplatin-resistant oral cancer cells. The purpose of this study was to examine the anticancer effect and molecular mechanism of BITC on human cisplatin-resistant oral cancer CAR cells. Our results demonstrated that BITC significantly reduced cell viability of CAR cells in a concentration- and time-dependent manner. BITC was found to cause apoptotic cell shrinkage and DNA fragmentation by morphologic observation and TUNEL/DAPI staining. Pretreatment of cells with a specific inhibitor of pan-caspase significantly reduced cell death caused by BITC. Colorimetric assay analyses also showed that the activities of caspase-3 and caspase-9 were elevated in BITC-treated CAR cells. An increase in ROS production and loss of mitochondria membrane potential (ΔΨm) occurred due to BITC exposure and was observed via flow cytometric analysis. Western blotting analyses demonstrated that the protein levels of Bax, Bad, cytochrome c, and cleaved caspase-3 were up-regulated, while those of Bcl-2, Bcl-xL and pro-caspase-9 were down-regulated in CAR cells after BITC challenge. In sum, the mitochondria-dependent pathway might contribute to BITC-induced apoptosis in human cisplatin-resistant oral cancer CAR cells.

Bortezomib Targets Sp Transcription Factors in Cancer Cells

Bortezomib alone and in combination with other anticancer agents are extensively used for chemotherapeutic treatment of multiple myeloma (MM) patients and are being developed for treating other cancers. Bortezomib acts through multiple pathways, and in this study with ANBL-6 and RPMI 8226 MM cells we show that bortezomib inhibited growth and induced apoptosis and that this was accompanied by downregulation of specificity protein (Sp) 1, Sp3, and Sp4 transcription factors that are overexpressed in these cells. Similar results were observed in pancreatic and colon cancer cells. The functional importance of this pathway was confirmed by showing that individual knockdown of Sp1, Sp3, and Sp4 in MM cells inhibited cell growth and induced apoptosis, and that this correlates with the results of previous studies in pancreatic, colon, and other cancer cell lines. The mechanism of bortezomib-mediated downregulation of Sp transcription factors in MM was due to the induction of caspase-8 and upstream factors, including Fas-associated death domain. These results demonstrate that an important underlying mechanism of action of bortezomib was due to the activation of caspase-8-dependent downregulation of Sp1, Sp3, Sp4, and pro-oncogenic Sp-regulated genes.

Specificity Protein Transcription Factors and Cancer: Opportunities for Drug Development

Specificity protein (Sp) transcription factors (TFs) such as Sp1 are critical for early development but their expression decreases with age and there is evidence that transformation of normal cells to cancer cells is associated with upregulation of Sp1, Sp3, and Sp4, which are highly expressed in cancer cells and tumors. Sp1 is a negative prognostic factor for pancreatic, colon, glioma, gastric, breast, prostate, and lung cancer patients. Functional studies also demonstrate that Sp TFs regulate genes responsible for cancer cell growth, survival, migration/invasion, inflammation and drug resistance, and Sp1, Sp3 and Sp4 are also nononcogene addiction (NOA) genes and important drug targets. The mechanisms of drug-induced downregulation of Sp TFs and pro-oncogenic Sp-regulated genes are complex and include ROS-dependent epigenetic pathways that initially decrease expression of the oncogene cMyc. Many compounds such as curcumin, aspirin, and metformin that are active in cancer prevention also exhibit chemotherapeutic activity and these compounds downregulate Sp TFs in cancer cell lines and tumors. The effects of these compounds on downregulation of Sp TFs in normal cells and the contribution of this response to their chemopreventive activity have not yet been determined. Cancer Prev Res; 11(7); 371-82. ©2018 AACR.

Design and Synthesis of Novel Reactive Oxygen Species Inducers for the Treatment of Pancreatic Ductal Adenocarcinoma

Altering redox homeostasis provides distinctive therapeutic opportunities for the treatment of pancreatic cancer. Quinazolinediones (QDs) are novel redox modulators that we previously showed to induce potent growth inhibition in pancreatic ductal adenocarcinoma (PDAC) cell lines. Our lead optimization campaign yielded QD325 as the most potent redox modulator candidate inducing substantial reactive oxygen species (ROS) in PDAC cells. Nascent RNA sequencing following treatments with the QD compounds revealed induction of stress responses in nucleus, endoplasmic reticulum, and mitochondria of pancreatic cancer cells. Furthermore, the QD compounds induced Nrf2-mediated oxidative stress and unfolded protein responses as demonstrated by dose-dependent increases in RNA synthesis of representative genes such as NQO1, HMOX1, DDIT3, and HSPA5. At higher concentrations, the QDs blocked mitochondrial function by inhibiting mtDNA transcription and downregulating the mtDNA-encoded OXPHOS enzymes. Importantly, treatments with QD325 were well tolerated in vivo and significantly delayed tumor growth in mice. Our study supports the development of QD325 as a new therapeutic in the treatment of PDAC.

G6PD promotes renal cell carcinoma proliferation through positive feedback regulation of p-STAT3

Ectopic Glucose 6-phosphate dehydrogenase (G6PD) expression plays important role in tumor cell metabolic reprogramming and results in poor prognosis of multiple malignancies. Our previous study indicated that G6PD is overexpressed in clear cell renal cell carcinoma (ccRCC), the most common subtype of RCC. However, its role in RCC is still unclear. Here, we demonstrate that G6PD is not only up-regulated in all types of RCC specimens but also displays higher activities in RCC cell lines. G6PD overexpression promoted RCC cell proliferation, altered cell cycle distribution, and enhanced xenografted RCC development. G6PD up-regulated ROS generation by facilitating NADPH-dependent NOX4 activation, which led to increased expression of p-STAT3 and CyclinD1. Enhanced ROS generation rescued the p-STAT3 and CyclinD1 expression reduction in G6PD-knockdown cells, while ROS scavengers reversed the up-regulated p-STAT3 and CyclinD1 expression in G6PD-overexpressing cells. Furthermore, p-STAT3 activated G6PD gene expression via binding to the G6PD promoter, demonstrating that p-STAT3 forms a positive feedback regulatory loop for G6PD overexpression. G6PD expression was up or down-regulated in response to the impact of p-STAT3 activators or inhibitors. Therefore, G6PD may be an effective RCC therapeutic target.

The Candida albicans Inhibitory Activity of the Extract from Papaya (Carica papaya L.) Seed Relates to Mitochondria Dysfunction

The inhibitory activity of the papaya seed extract (PSE) on Candida albicans (C. albicans) was determined by turbidimetry method. The inhibitory mechanisms were also evaluated from the prospective of reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) decrease, and the activities of four complex enzymes in mitochondria respiratory chain. Results obtained from this study indicated that the PSE exhibited an effective inhibitory activity on C. albicans and induced significant accumulation of ROS and collapse of MMP. The Complex I and Complex III exhibited continues significant decrease in mitochondrial enzyme activity assays, but the Complex II and Complex IV activities were not positively correlated. Furthermore, the GC-MS analysis demonstrated that the PSE represents a rich and high-purity source of benzyl isothiocyanate (BITC), which indicated the BITC may be responsible for the mitochondrial dysfunction.

Piperlongumine Induces Reactive Oxygen Species (ROS)-Dependent Downregulation of Specificity Protein Transcription Factors

Piperlongumine is a natural product found in the plant species Piper longum, and this compound exhibits potent anticancer activity in multiple tumor types and has been characterized as an inducer of reactive oxygen species (ROS). Treatment of Panc1 and L3.6pL pancreatic, A549 lung, 786-O kidney, and SKBR3 breast cancer cell lines with 5 to 15 μmol/L piperlongumine inhibited cell proliferation and induced apoptosis and ROS, and these responses were attenuated after cotreatment with the antioxidant glutathione. Piperlongumine also downregulated expression of Sp1, Sp3, Sp4, and several pro-oncogenic Sp-regulated genes, including cyclin D1, survivin, cMyc, EGFR and hepatocyte growth factor receptor (cMet), and these responses were also attenuated after cotreatment with glutathione. Mechanistic studies in Panc1 cells showed that piperlongumine-induced ROS decreased expression of cMyc via an epigenetic pathway, and this resulted in downregulation of cMyc-regulated miRNAs miR-27a, miR-20a, and miR-17 and induction of the transcriptional repressors ZBTB10 and ZBTB4. These repressors target GC-rich Sp-binding sites to decrease transactivation. This pathway observed for piperlongumine in Panc1 cells has previously been reported for other ROS-inducing anticancer agents and shows that an important underlying mechanism of action of piperlongumine is due to downregulation of Sp1, Sp3, Sp4, and pro-oncogenic Sp-regulated genes. Cancer Prev Res; 10(8); 467-77. ©2017 AACR.