SVCT-2 determines the sensitivity to ascorbate-induced cell death in cholangiocarcinoma cell lines and patient derived xenografts. Cancer Lett. 2017;398:1-11. [PMID: 28385602 DOI: 10.1016/j.canlet.2017.03.039]

The level of active DNA demethylation compounds in leukocytes and urine samples as potential epigenetic biomarkers in breast cancer patients

The active DNA demethylation process, which involves TET proteins, can affect DNA methylation pattern. TET dependent demethylation results in DNA hypomethylation by oxidation 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) and its derivatives. Moreover, TETs' activity may be upregulated by ascorbate. Given that aberrant DNA methylation of genes implicated in breast carcinogenesis may be involved in tumor progression, we wanted to determine whether breast cancer patients exert changes in the active DNA demethylation process. The study included blood samples from breast cancer patients (n = 74) and healthy subjects (n = 71). We analyzed the expression of genes involved in the active demethylation process (qRT-PCR), and 5-mC and its derivatives level (2D-UPLC MS/MS). The ascorbate level was determined using UPLC-MS. Breast cancer patients had significantly higher TET3 expression level, lower 5-mC and 5-hmC DNA levels. TET3 was significantly increased in luminal B breast cancer patients with expression of hormone receptors. Moreover, the ascorbate level in the plasma of breast cancer patients was decreased with the accompanying increase of sodium-dependent vitamin C transporters (SLC23A1 and SLC23A2). The presented study indicates the role of TET3 in DNA demethylation in breast carcinogenesis.

Biodistribution and radiation dosimetry in cancer patients of the ascorbic acid analogue 6-Deoxy-6-[18F] fluoro-L-ascorbic acid PET imaging: first-in-human study

PURPOSE

Clinical studies on the use of ascorbic acid (AA) have become a hot spot in cancer research. There remains an unmet need to assess AA utilization in normal tissues and tumors. 6-Deoxy-6-[18F]fluoro-L-ascorbic acid ([18F]DFA) displayed distinctive tumor localization and similar distribution as AA in mice. In this study, to evaluate the distribution, tumor detecting ability and radiation dosimetry of [18F]DFA in humans, we performed the first-in-human PET imaging study.

METHODS

Six patients with a variety of cancers underwent whole-body PET/CT scans after injection of 313-634 MBq of [18F]DFA. Five sequential dynamic emission scans in each patient were acquired at 5-60 min. Regions of interest (ROI) were delineated along the edge of the source-organ and tumor on the transverse PET slice. Tumor-to-background ratio (TBR) was obtained using the tumor SUVmax to background SUVmean. Organ residence times were calculated via time-activity curves, and human absorbed doses were estimated from organ residence time using the medical internal radiation dosimetry method.

RESULTS

[18F]DFA was well tolerated in all subjects without serious adverse event. The high uptake was found in the liver, adrenal glands, kidneys, choroid plexus, and pituitary gland. [18F]DFA accumulated in tumor rapidly and the TBR increased over time. The average SUVmax of [18F]DFA in tumor lesions was 6.94 ± 3.92 (range 1.62-22.85, median 5.94). The organs with the highest absorbed doses were the liver, spleen, adrenal glands, and kidneys. The mean effective dose was estimated to be 1.68 ± 0.36 E-02 mSv/MBq.

CONCLUSIONS

[18F]DFA is safe to be used in humans. It showed a similar distribution pattern as AA, and displayed high uptake and retention in tumors with appropriate kinetics. [18F]DFA might be a promising radiopharmaceutical in identifying tumors with high affinity for SVCT2 and monitoring AA distribution in both normal tissues and tumors.

TRIAL REGISTRATION

Chinese Clinical Trial Registry; Registered Number: ChiCTR2200057842 (registered 19 March 2022).

Curcumin inhibits human cancer cell growth and migration through downregulation of SVCT2

Curcumin is a natural polyphenol that is extracted from the rhizomes of the turmeric plant (Curcuma longa), a member of the ginger family. It has been used for centuries in traditional Indian and Chinese medicine for its medicinal properties, including anti-inflammatory, antioxidant and antitumor effects. SVCT2 (Solute Carrier Family 23 Member 2, also known as SLC23A2) is a protein that plays a role in the transport of Vitamin C (Ascorbic Acid) into cells. SVCT2 plays an important role in tumor progression and metastasis, however, the molecular mechanisms of curcumin on SVCT2 have not been studied to date. Curcumin treatment inhibited proliferation and migration of cancer cells in a dose dependent manner. We found that curcumin reduced the expression of SVCT2 in cancer cells with a wild type p53, but not in those with a mutant type of p53. SVCT2 downregulation also reduced the MMP2 activity. Taken together, our results indicate that curcumin inhibited human cancer cell growth and migration by regulating SVCT2 through a downregulating p53. These findings provide new insights into the molecular mechanisms of curcumin's anticancer effects and potential therapeutic strategies for the treatment of metastatic migration.

Applications, impacts, and management of biochar persistent free radicals: A review

Biochar is a promising environmental contaminant remediation agent because of its adsorptive and catalytic properties. However, the environmental effects of persistent free radicals (PFRs) produced by biomass pyrolysis (biochar production) are still poorly understood, though they have received increasing research attention in recent years. Although PFRs both directly and indirectly mediate biochar's removal of environmental pollutants, they also have the potential to cause ecological damage. In order to support and sustain biochar applications, effective strategies are needed to control the negative effects of biochar PFRs. Yet, there has been no systematic evaluation of the environmental behavior, risks, or management techniques of biochar PFRs. Thus, this review: 1) outlines the formation mechanisms and types of biochar PFRs, 2) evaluates their environmental applications and potential risks, 3) summarizes their environmental migration and transformation, and 4) explores effective management strategies for biochar PFRs during both production and application phases. Finally, future research directions are recommended.

Relevant Membrane Transport Proteins as Possible Gatekeepers for Effective Pharmacological Ascorbate Treatment in Cancer

Despite the increasing number of newly diagnosed malignancies worldwide, therapeutic options for some tumor diseases are unfortunately still limited. Interestingly, preclinical but also some clinical data suggest that the administration of pharmacological ascorbate seems to respond well, especially in some aggressively growing tumor entities. The membrane transport and channel proteins are highly relevant for the use of pharmacological ascorbate in cancer therapy and are involved in the transfer of active substances such as ascorbate, hydrogen peroxide, and iron that predominantly must enter malignant cells to induce antiproliferative effects and especially ferroptosis. In this review, the relevant conveying proteins from cellular surfaces are presented as an integral part of the efficacy of pharmacological ascorbate, considering the already known genetic and functional features in tumor tissues. Accordingly, candidates for diagnostic markers and therapeutic targets are mentioned.

Ascorbate Is a Primary Antioxidant in Mammals

Ascorbate (vitamin C in primates) functions as a cofactor for a number of enzymatic reactions represented by prolyl hydroxylases and as an antioxidant due to its ability to donate electrons, which is mostly accomplished through non-enzymatic reaction in mammals. Ascorbate directly reacts with radical species and is converted to ascorbyl radical followed by dehydroascorbate. Ambiguities in physiological relevance of ascorbate observed during in vivo situations could be attributed in part to presence of other redox systems and the pro-oxidant properties of ascorbate. Most mammals are able to synthesize ascorbate from glucose, which is also considered to be an obstacle to verify its action. In addition to animals with natural deficiency in the ascorbate synthesis, such as guinea pigs and ODS rats, three strains of mice with genetic removal of the responsive genes (GULO, RGN, or AKR1A) for the ascorbate synthesis have been established and are being used to investigate the physiological roles of ascorbate. Studies using these mice, along with ascorbate transporter (SVCT)-deficient mice, largely support its ability in protection against oxidative insults. While combined actions of ascorbate in regulating epigenetics and antioxidation appear to effectively prevent cancer development, pharmacological doses of ascorbate and dehydroascorbate may exert tumoricidal activity through redox-dependent mechanisms.

The power of heteronemin in cancers

Heteronemin (Haimian jing) is a sesterterpenoid-type natural marine product that is isolated from sponges and has anticancer properties. It inhibits cancer cell proliferation via different mechanisms, such as reactive oxygen species (ROS) production, cell cycle arrest, apoptosis as well as proliferative gene changes in various types of cancers. Recently, the novel structure and bioactivity evaluation of heteronemin has received extensive attention. Hormones control physiological activities regularly, however, they may also affect several abnormalities such as cancer. L-Thyroxine (T₄), steroid hormones, and epidermal growth factor (EGF) up-regulate the accumulation of checkpoint programmed death-ligand 1 (PD-L1) and promote inflammation in cancer cells. Heteronemin suppresses PD-L1 expression and reduces the PD-L1-induced proliferative effect. In the current review, we evaluated research and evidence regarding the antitumor effects of heteronemin and the antagonizing effects of non-peptide hormones and growth factors on heteronemin-induced anti-cancer properties and utilized computational molecular modeling to explain how these ligands interacted with the integrin αvβ3 receptors. On the other hand, thyroid hormone deaminated analogue, tetraiodothyroacetic acid (tetrac), modulates signal pathways and inhibits cancer growth and metastasis. The combination of heteronemin and tetrac derivatives has been demonstrated to compensate for anti-proliferation in cancer cells under different circumstances. Overall, this review outlines the potential of heteronemin in managing different types of cancers that may lead to its clinical development as an anticancer agent.

Influence of Miscanthus Rhizome Pyrolysis Operating Conditions on Products Properties

Waste from the Miscanthus production cycle may be a promising source of material for the pyrolysis and biochar production. The biochar can be used to enrich the soil on which the crop grows, thus increasing productivity. A sample of Miscanthus rhizomes was used as a raw material in a series of experiments in order to find the most suitable conditions for the preparation of biochar. Miscanthus biochar was prepared in a laboratory unit using four different temperatures (i.e., 400, 500, 600 and 700 °C). All pyrolysis products were subsequently evaluated in terms of their quality and product yields were determined. For a temperature of 600 °C and a residence time of 2 h, the appropriate properties of biochar were achieved and the process was still economical. The biochar contained a minimal number of polycyclic aromatic hydrocarbons and a high percentage of carbon. Surface area was measured to be 217 m2/g. The aqueous extract of biochar was alkaline.

The potential role of vitamin C in empowering cancer immunotherapy

Vitamin C also known as L-ascorbic acid is a nutrient naturally occurring in many fruits and vegetables and widely known for its potent antioxidant activity. Several studies have highlighted the importance of using high dose vitamin C as an adjuvant anti-cancer therapy. Interestingly, it has been shown that vitamin C is able to modulate the anti-cancer immune response and to help to overcome the resistance to immune checkpoints blockade (ICB) drugs such as cytotoxic T-lymphocyte antigen 4 (CLTA-4) and programmed cell death ligand 1 (PD-L1/PD-1) inhibitors. Indeed, it was reported that vitamin C regulates several mechanisms developed by cancer cells to escape T cells immune response and resist ICB. Understanding the role of vitamin C in the anti-tumor immune response will pave the way to the development of novel combination therapies that would enhance the response of cancer patients to ICB immunotherapy. In this review, we discuss the effect of vitamin C on the immune system and its potential role in empowering cancer immunotherapy through its pro-oxidant potential, its ability to modulate epigenetic factors and its capacity to regulate the expression of different cytokines involved in the immune response.

Combinatorial Therapy of High Dose Vitamin C and PARP Inhibitors in DNA Repair Deficiency: A Series of 8 Patients

Background:

Tumor-specific DNA repair defects are ubiquitous in cancerous tissue, which offers a potential for clinical gain to build on these perturbations. Intravenous high-dose vitamin C (IVC) triggers the formation of hydrogen peroxide (H₂O₂), which contributes to Fenton chemistry producing hydroxyl radicals (-OH), causing selective damage to DNA. Herein, we evaluated the therapeutic response to IVC and PARP inhibitors (PARPi) in combination in 8 patients with a deficiency of homologous recombination repair system (dHRR) in a 3-year period.

Material and Methods:

Eight patients with progressive stage IV malignancy, who were pre-treated with conventional methods, were admitted to our clinic. Subsequent therapy has included IVC at a dose that was set to be in the range of 1 to 1.5 g/kg, although 1.25 g/kg was dominantly administered. Furthermore, following genomic evaluation, PARPi (niraparib or olaparib or talazoparib) was chosen to be used in combination with IVC which was administered 2 to 4 times a week.

Results:

In the present study, we achieved partial response in 5 patients and complete response in 3 patients. Grade 2 anemia and fatigue toxicities were observed in some cases, while grade 3 toxicity was not found in any of the patients.

Conclusion:

Our 8 patient case study shows that IVC could be a plausible additional therapy for HRR deficiency. Although the single agent PARPi therapy is effective for metastatic disease, an overall survival (OS) advantage has not been demonstrated. Our results suggest that adding IVC can improve PARPi therapy outcomes. To fully endorse the results stated above, combinatorial therapy of intravenous high dose vitamin C and PARP inhibitors needs to be reviewed in broader cohorts of patients.

Vitamin C Transporters and Their Implications in Carcinogenesis

Vitamin C is implicated in various bodily functions due to its unique properties in redox homeostasis. Moreover, vitamin C also plays a great role in restoring the activity of 2-oxoglutarate and Fe²⁺ dependent dioxygenases (2-OGDD), which are involved in active DNA demethylation (TET proteins), the demethylation of histones, and hypoxia processes. Therefore, vitamin C may be engaged in the regulation of gene expression or in a hypoxic state. Hence, vitamin C has acquired great interest for its plausible effects on cancer treatment. Since its conceptualization, the role of vitamin C in cancer therapy has been a controversial and disputed issue. Vitamin C is transferred to the cells with sodium dependent transporters (SVCTs) and glucose transporters (GLUT). However, it is unknown whether the impaired function of these transporters may lead to carcinogenesis and tumor progression. Notably, previous studies have identified SVCTs’ polymorphisms or their altered expression in some types of cancer. This review discusses the potential effects of vitamin C and the impaired SVCT function in cancers. The variations in vitamin C transporter genes may regulate the active transport of vitamin C, and therefore have an impact on cancer risk, but further studies are needed to thoroughly elucidate their involvement in cancer biology.

New promising developments for potential therapeutic applications of high-dose ascorbate as an anticancer drug

Vitamin C (ascorbate) is an essential dietary requirement, with fundamental redox, anti-oxidant functions at physiologic concentrations. Vitamin C is a cofactor for Fe²⁺ and 2-oxoglutarate-dependent dioxygenases, englobing large families of enzymes, including also epigenetic regulators of DNA and histone methylation. Importantly, vitamin C is involved in the control of the activity of TET (ten-eleven translocation) enzymes, key epigenetic regulators. For this spectrum of activities, often involving pathways deregulated in cancer cells, vitamin C possesses some pharmacologic activities that can be exploited in anticancer therapy. In particular, the capacity of pharmacological doses of vitamin C to target redox imbalance and to rescue deregulated epigenetic program observed in some cancer cells represents a consistent therapeutic potentiality. Several recent studies have identified some cancer subsets that could benefit from the pharmacological activities of vitamin C. The identification of these potentially responsive patients will help to carefully define controlled clinical trials aiming to evaluate the anticancer activity of Vitamin C.

Liquid Biopsies in Renal Cell Carcinoma-Recent Advances and Promising New Technologies for the Early Detection of Metastatic Disease

Clear cell renal cell carcinoma (ccRCC) displays a highly varying clinical progression, from slow growing localized tumors to very aggressive metastatic disease (mRCC). Almost a third of all patients with ccRCC show metastatic dissemination at presentation while another third develop metastasis during the course of the disease. Survival rates of mRCC patients remain low despite the development of novel targeted treatment regimens. Biomarkers indicating disease progression could help to define its aggressive potential and thus guide patient management. However, molecular markers that can reliably assess metastatic dissemination and disease recurrence in ccRCC have not been recommended for clinical practice to date. Liquid biopsies could provide an attractive and non-invasive method to determine the risk of recurrence or metastatic dissemination during follow-up and thus assist the search for surveillance biomarkers in ccRCC tumors. A wide spectrum of circulating molecules have already shown considerable potential for ccRCC diagnosis and prognostication. In this review, we outline state of the art of the key circulating analytes such as cfDNA, cfRNA, proteins, and exosomes that may serve as biomarkers for the longitudinal monitoring of ccRCC progression to metastasis. Moreover, we address some of the prevailing limitations in the past approaches and present promising adoptable technologies that could help to pursue the implementation of liquid biopsies as a prognostic tool for mRCC.

Evolution of the Experimental Models of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare, aggressive disease with poor overall survival. In advanced cases, surgery is often not possible or fails; in addition, there is a lack of effective and specific therapies. Multidisciplinary approaches and advanced technologies have improved the knowledge of CCA molecular pathogenesis, highlighting its extreme heterogeneity and high frequency of genetic and molecular aberrations. Effective preclinical models, therefore, should be based on a comparable level of complexity. In the past years, there has been a consistent increase in the number of available CCA models. The exploitation of even more complex CCA models is rising. Examples are the use of CRISPR/Cas9 or stabilized organoids for in vitro studies, as well as patient-derived xenografts or transgenic mouse models for in vivo applications. Here, we examine the available preclinical CCA models exploited to investigate: (i) carcinogenesis processes from initiation to progression; and (ii) tools for personalized therapy and innovative therapeutic approaches, including chemotherapy and immune/targeted therapies. For each model, we describe the potential applications, highlighting both its advantages and limits.

Vitamin C as an Anticancer Agent: Regulation of Signaling Pathways

Treatment options for effective treatment of cancer with minimum off-target effects and maximum clinical outcomes have remained overarching goals in the clinical oncology. Vitamin C has remained in the shadows of controversy since the past few decades; burgeoning evidence has started to shed light on wide-ranging anticancer effects exerted by Vitamin C to induce apoptosis in drug-resistant cancer cells, inhibit uncontrolled proliferation of the cancer cells and metastatic spread. Landmark achievements in molecular oncology have ushered in a new era, and researchers have focused on the identification of oncogenic pathways regulated by Vitamin C in different cancers. However, there are visible knowledge gaps in our understanding related to the ability of Vitamin C to modulate a myriad of transduction cascades. There are scattered pieces of scientific evidence about promising potential of Vitamin C to regulate JAK-STAT, TGF/SMAD, TRAIL and microRNAs in different cancers. However, published data is insufficient and needs to be investigated comprehensively to enable basic and clinical researchers to reap full benefits and promote result-oriented transition of Vitamin C into various phases of clinical trials. In this review, we will emphasize on available evidence related to the regulation of oncogenic cell signaling pathways by Vitamin C in different cancers. We will also highlight the conceptual gaps, which need detailed and cutting-edge research.

Labile iron affects pharmacological ascorbate-induced toxicity in osteosarcoma cell lines

Vitamin C and iron are both important nutrients for humans and involved in several physiological processes. The biological activities of vitamin C and iron are based on their abilities to accept or donate electrons. Although vitamin C is well known as an excellent electron donor in physiological conditions, it also has pro-oxidant properties, especially with catalytic metal iron. Cancer cells have a higher iron requirement than normal cells, which allows pharmacological ascorbate to kill cancer cells selectively. In this study, we demonstrated that the levels of H₂O₂ in cells were significantly raised after treated with pharmacological ascorbate, and intracellular labile iron could increase pharmacological ascorbate-mediated oxidative stress by Fenton reaction. Catalytic metal iron plays opposite roles in and outside cells. Intracellular excess labile iron improved ascorbate-induced toxicity, while the excess labile iron in the medium abolished ascorbate-induced toxicity. Fe³⁺ and Fe²⁺ have the same effect on ascorbate-induced toxicity, but Fe³⁺ chelator deferoxamine (DFO) has a profound inhibition effect than Fe²⁺ chelator 2,2'-bipyridyl (BIP) on ascorbate-induced toxicity. The influence of intracellular labile iron and ascorbate on the ferritin expression may cause selective sensitivity in osteosarcoma cell lines on pharmacological ascorbate. High iron requirement of many cancer cells facilitates pharmacological ascorbate on cancer treatment. In addition, increasing iron content in tumour tissue may be effective strategies to improve the effects of pharmacological ascorbate.

Biliary tract cancer patient-derived xenografts: Surgeon impact on individualized medicine

BACKGROUND & AIMS

Biliary tract tumors are uncommon but highly aggressive malignancies with poor survival outcomes. Due to their low incidence, research into effective therapeutics has been limited. Novel research platforms for pre-clinical studies are desperately needed. We sought to develop a patient-derived biliary tract cancer xenograft catalog.

METHODS

With appropriate consent and approval, surplus malignant tissues were obtained from surgical resection or radiographic biopsy and implanted into immunocompromised mice. Mice were monitored for xenograft growth. Established xenografts were verified by a hepatobiliary pathologist. Xenograft characteristics were correlated with original patient/tumor characteristics and oncologic outcomes. A subset of xenografts were then genomically characterized using Mate Pair sequencing (MPseq).

RESULTS

Between October 2013 and January 2018, 87 patients with histologically confirmed biliary tract carcinomas were enrolled. Of the 87 patients, 47 validated PDX models were successfully generated. The majority of the PDX models were created from surgical resection specimens (n = 44, 94%), which were more likely to successfully engraft when compared to radiologic biopsies (p = 0.03). Histologic recapitulation of original patient tumor morphology was observed in all xenografts. Successful engraftment was an independent predictor for worse recurrence-free survival. MPseq showed genetically diverse tumors with frequent alterations of CDKN2A, SMAD4, NRG1, TP53. Sequencing also identified worse survival in patients with tumors containing tetraploid genomes.

CONCLUSIONS

This is the largest series of biliary tract cancer xenografts reported to date. Histologic and genomic analysis of patient-derived xenografts demonstrates accurate recapitulation of original tumor morphology with direct correlations to patient outcomes. Successful development of biliary cancer tumografts is feasible and may be used to direct subsequent therapy in high recurrence risk patients.

LAY SUMMARY

Patient biliary tract tumors grown in immunocompromised mice are an invaluable resource in the treatment of biliary tract cancers. They can be used to guide individualized cancer treatment in high-risk patients.

Therapeutic Use of Vitamin C in Cancer: Physiological Considerations

Since the early studies of William J. McCormick in the 1950s, vitamin C has been proposed as a candidate for the treatment of cancer. A number of reports have shown that pharmacological concentrations of vitamin C selectively kill cancer cells in vitro and decrease the growth rates of a number of human tumor xenografts in immunodeficient mice. However, up to the date there is still doubt regarding this possible therapeutic role of vitamin C in cancer, mainly because high dose administration in cancer patients has not showed a clear antitumor activity. These apparent controversial findings highlight the fact that we lack information on the interactions that occurs between cancer cells and vitamin C, and if these transformed cells can uptake, metabolize and compartmentalize vitamin C like normal human cells do. The role of SVCTs and GLUTs transporters, which uptake the reduced form and the oxidized form of vitamin C, respectively, has been recently highlighted in the context of cancer showing that the relationship between vitamin C and cancer might be more complex than previously thought. In this review, we analyze the state of art of the effect of vitamin C on cancer cells in vitro and in vivo, and relate it to the capacity of cancer cells in acquiring, metabolize and compartmentalize this nutrient, with its implications on the potential therapeutic role of vitamin C in cancer.

Plasma Membrane Transporters as Biomarkers and Molecular Targets in Cholangiocarcinoma

The dismal prognosis of patients with advanced cholangiocarcinoma (CCA) is due, in part, to the extreme resistance of this type of liver cancer to available chemotherapeutic agents. Among the complex mechanisms accounting for CCA chemoresistance are those involving the impairment of drug uptake, which mainly occurs through transporters of the superfamily of solute carrier (SLC) proteins, and the active export of drugs from cancer cells, mainly through members of families B, C and G of ATP-binding cassette (ABC) proteins. Both mechanisms result in decreased amounts of active drugs able to reach their intracellular targets. Therefore, the “cancer transportome”, defined as the set of transporters expressed at a given moment in the tumor, is an essential element for defining the multidrug resistance (MDR) phenotype of cancer cells. For this reason, during the last two decades, plasma membrane transporters have been envisaged as targets for the development of strategies aimed at sensitizing cancer cells to chemotherapy, either by increasing the uptake or reducing the export of antitumor agents by modulating the expression/function of SLC and ABC proteins, respectively. Moreover, since some elements of the transportome are differentially expressed in CCA, their usefulness as biomarkers with diagnostic and prognostic purposes in CCA patients has been evaluated.

Piperlongumine induces autophagy in biliary cancer cells via reactive oxygen species-activated Erk signaling pathway

Biliary cancer (BC) is an aggressive neoplasm with high mortality. BC can be categorized into three groups: Intrahepatic cholangiocarcinoma (CCA; also known as bile duct cancer), extrahepatic cholangiocarcinoma and gallbladder cancer. Due to its heterogeneity and aggressiveness, the response to current chemotherapy and radiotherapy methods in patients with BC is poor. Therefore, there is an urgent requirement to develop drugs to treat BC. Piperlongumine (PL), a naturally occurring small molecule isolated from Piper longum L., exhibits anticancer activity by inducing reactive oxygen species (ROS) production. In the present study, the effects of PL on cell proliferation, cell cycle, apoptosis and autophagy in BC cells were investigated. PL induced BC cell death in a concentration‑ and time‑dependent manner by inducing ROS production. PL induced cell cycle arrest in CCA cells (HuCCT‑1) and gallbladder cancer cells (OCUG‑1) cells, but with distinct cell cycle distribution profiles. PL caused G2/M cell cycle arrest in HuCCT‑1 cells, and G0/G1 cell cycle arrest in OCUG‑1 cells. PL induced apoptosis and autophagy; PL treatment induced accumulation of LC3‑II in a concentration‑ and time‑dependent manner. The Erk signaling pathway appeared to be involved in autophagy induction. Application of the ROS scavenger, N‑acetyl‑l‑cysteine, to BC cells attenuated the cell death, cell cycle arrest, apoptosis and autophagy induced by PL treatment. These findings indicated that PL may be a potential agent for BC treatment in the future.

Hepatomas are exquisitely sensitive to pharmacologic ascorbate (P-AscH-)

Rationale: Ascorbate is an essential micronutrient known for redox functions at normal physiologic concentrations. In recent decades, pharmacological ascorbate has been found to selectively kill tumour cells. However, the dosing frequency of pharmacologic ascorbate in humans has not yet been defined.

Methods: We determined that among five hepatic cell lines, Huh-7 cells were the most sensitive to ascorbate. The effects of high-dose ascorbate on hepatoma were therefore assessed using Huh-7 cells and xenograft tumour mouse model.

Results: In Huh-7 cells, ascorbate induced a significant increase in the percentage of cells in the G0/G1 phase, apoptosis and intracellular levels of ROS. High doses of ascorbate (4.0 pmol cell^-1), but not low doses of ascorbate (1.0 pmol cell^-1), also served as a pro-drug that killed hepatoma cells by altering mitochondrial respiration. Furthermore, in a Huh-7 cell xenograft tumour mouse model, intraperitoneal injection of ascorbate (4.0 g/kg/3 days) but not a lower dose of ascorbate (2.0 g/kg/3 days) significantly inhibited tumour growth. Gene array analysis of HCC tumour tissue from xenograft mice given IP ascorbate (4.0 g/kg/3 days) identified changes in the transcript levels of 192 genes/ncRNAs involved in insulin receptor signalling, metabolism and mitochondrial respiration. Consistent with the array data, gene expression levels of AGER, DGKK, ASB2, TCP10L2, Lnc-ALCAM-3, and Lnc-TGFBR2-1 were increased 2.05-11.35 fold in HCC tumour tissue samples from mice treated with high-dose ascorbate, and IHC staining analysis also verified that AGER/RAGE and DGKK proteins were up-regulated, which implied that AGER/RAGE and DGKK activation might be related to oxidative stress, leading to hepatoma cell death.

Conclusions: Our studies identified multiple mechanisms are responsible for the anti-tumour activity of ascorbate and suggest high doses of ascorbate with less frequency will act as a novel therapeutic agent for liver cancer in vivo.

Redox modifications of cysteine-containing proteins, cell cycle arrest and translation inhibition: Involvement in vitamin C-induced breast cancer cell death

Vitamin C (VitC) possesses pro-oxidant properties at high pharmacologic concentrations which favor repurposing VitC as an anti-cancer therapeutic agent. However, redox-based anticancer properties of VitC are yet partially understood. We examined the difference between the reduced and oxidized forms of VitC, ascorbic acid (AA) and dehydroascorbic acid (DHA), in terms of cytotoxicity and redox mechanisms toward breast cancer cells. Our data showed that AA displayed higher cytotoxicity towards triple-negative breast cancer (TNBC) cell lines in vitro than DHA. AA exhibited a similar cytotoxicity on non-TNBC cells, while only a minor detrimental effect on noncancerous cells. Using MDA-MB-231, a representative TNBC cell line, we observed that AA- and DHA-induced cytotoxicity were linked to cellular redox-state alterations. Hydrogen peroxide (H2O2) accumulation in the extracellular medium and in different intracellular compartments, and to a lesser degree, intracellular glutathione oxidation, played a key role in AA-induced cytotoxicity. In contrast, DHA affected glutathione oxidation and had less cytotoxicity. A "redoxome" approach revealed that AA treatment altered the redox state of key antioxidants and a number of cysteine-containing proteins including many nucleic acid binding proteins and proteins involved in RNA and DNA metabolisms and in energetic processes. We showed that cell cycle arrest and translation inhibition were associated with AA-induced cytotoxicity. Finally, bioinformatics analysis and biological experiments identified that peroxiredoxin 1 (PRDX1) expression levels correlated with AA differential cytotoxicity in breast cancer cells, suggesting a potential predictive value of PRDX1. This study provides insight into the redox-based mechanisms of VitC anticancer activity, indicating that pharmacologic doses of VitC and VitC-based rational drug combinations could be novel therapeutic opportunities for triple-negative breast cancer.

Animal models of cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive biliary tract malignancy with a poor overall prognosis. There is a critical need to develop effective targeted therapies for the treatment of this lethal disease. In an effort to address this challenge, preclinical in vivo studies have become paramount in understanding CCA carcinogenesis, progression, and therapy. Various CCA animal models exist including carcinogen-based models in which animals develop CCA after exposure to a carcinogen, genetically engineered mouse models in which genetic changes are induced in mice leading to CCA, murine syngeneic orthotopic models, as well as xenograft tumors derived from xenotransplantation of CCA cells, organoids, and patient-derived tissue. Each type has distinct advantages as well as shortcomings. In the ideal animal model of CCA, the tumor arises from the biliary tract in an immunocompetent host with a species-matched tumor microenvironment. Such a model would also be time-efficient, recapitulate the genetic and histopathological features of human CCA, and predict therapeutic response in humans. Recently developed biliary tract transduction and orthotopic syngeneic transplant mouse models encompass several of these elements. Herein, we review the different animal models of CCA, their advantages and deficiencies, as well as features which mimic human CCA.

Oxidized Vitamin C (DHA) Overcomes Resistance to EGFR-targeted Therapy of Lung Cancer through Disturbing Energy Homeostasis

Switching aerobic respiration to anaerobic glycolysis of cancer cells plays an important role in development and progression of acquired resistance. Since vitamin C enabled the inhibition of glycolysis of cancer cells, and erlotinib-resistant sub-line of HCC827 (ER6 cells) switched its metabolic features to higher glycolysis for survival, we hypothesize that vitamin C is able to inhibit glycolysis of ER6 cells. In this study, we found that both reduced vitamin C and oxidized vitamin C (DHA) could selectively suppress the viability of ER6 cells. DHA was efficient in inhibiting glycolysis and leading to energy crisis, which could be one mechanism for overcoming drug resistance to erlotinib of ER6 cells. Our data suggest that applying DHA could be a novel treatment strategy for NSCLC with acquired resistance to targeted therapy.

Concentration Does Matter: The Beneficial and Potentially Harmful Effects of Ascorbate in Humans and Plants

SIGNIFICANCE

Ascorbate (Asc) is an essential compound both in animals and plants, mostly due to its reducing properties, thereby playing a role in scavenging reactive oxygen species (ROS) and acting as a cofactor in various enzymatic reactions. Recent Advances: Growing number of evidence shows that excessive Asc accumulation may have negative effects on cellular functions both in humans and plants; inter alia it may negatively affect signaling mechanisms, cellular redox status, and contribute to the production of ROS via the Fenton reaction.

CRITICAL ISSUES

Both plants and humans tightly control cellular Asc levels, possibly via biosynthesis, transport, and degradation, to maintain them in an optimum concentration range, which, among other factors, is essential to minimize the potentially harmful effects of Asc. On the contrary, the Fenton reaction induced by a high-dose Asc treatment in humans enables a potential cancer-selective cell death pathway.

FUTURE DIRECTIONS

The elucidation of Asc induced cancer selective cell death mechanisms may give us a tool to apply Asc in cancer therapy. On the contrary, the regulatory mechanisms controlling cellular Asc levels are also to be considered, for example, when aiming at generating crops with elevated Asc levels.

Retinol palmitate and ascorbic acid: Role in oncological prevention and therapy

Cancer development has been directly related to oxidative stress. During chemotherapy, some cancer patients use dietary antioxidants to avoid nutritional deficiencies due to cancer treatment. Among the antioxidants consumed, there are vitamins, including retinyl palmitate (PR) and ascorbic acid (AA), which have the capacity to reduce free radicals formation, protect cellular structures and maintain the cellular homeostasis. This systematic review evaluated the antioxidant and antitumor mechanisms of retinol palmitate (a derivative of vitamin A) and/or ascorbic acid (vitamin C) in cancer-related studies. Ninety-seven (97) indexed articles in the databases PubMed and Science Direct, published between 2013 and 2017, including 23 clinical studies (5 for every single compound while 13 in interaction) and 74 non-clinical studies (37 for retinol palmitate, 36 for ascorbic acid and 1 in interaction) were considered. Antioxidant and antitumor effects, with controversies over dosage and route of administration, were observed for the test compounds in their isolated form or associated in clinical studies. Prevention of cancer risks against oxidative damage was seen in lower doses of retinol palmitate and/or vitamin C. However, at high doses, they can generate reactive oxygen species, cytotoxicity and apoptosis in test systems. Non-clinical studies using cell lines have allowed understanding the mechanisms related to antioxidants and antitumor effects of the isolated compounds, however, studies on vitamin interactions, acting as antioxidants and/or antitumor are still rare and controversial. More studies, mainly related to modulation of antineoplastic drugs are needed for understanding the risks and benefits of their use during treatment in order to achieve effectiveness in cancer therapy and patient's quality of life.

Vitamin C in the critically ill - indications and controversies

Ascorbic acid (vitamin C) elicits pleiotropic effects in the body. Among its functions, it serves as a potent anti-oxidant, a co-factor in collagen and catecholamine synthesis, and a modulator of immune cell biology. Furthermore, an increasing body of evidence suggests that high-dose vitamin C administration improves hemodynamics, end-organ function, and may improve survival in critically ill patients. This article reviews studies that evaluate vitamin C in pre-clinical models and clinical trials with respect to its therapeutic potential.

Intravenous Vitamin C for Cancer Therapy - Identifying the Current Gaps in Our Knowledge

The use of intravenous vitamin C (IVC) for cancer therapy has long been an area of intense controversy. Despite this, high dose IVC has been administered for decades by complementary health care practitioners and physicians, with little evidence base resulting in inconsistent clinical practice. In this review we pose a series of questions of relevance to both researchers and clinicians, and also patients themselves, in order to identify current gaps in our knowledge. These questions include: Do oncology patients have compromised vitamin C status? Is intravenous the optimal route of vitamin C administration? Is IVC safe? Does IVC interfere with chemotherapy or radiotherapy? Does IVC decrease the toxic side effects of chemotherapy and improve quality of life? What are the relevant mechanisms of action of IVC? What are the optimal doses, frequency, and duration of IVC therapy? Researchers have made massive strides over the last 20 years and have addressed many of these important aspects, such as the best route for administration, safety, interactions with chemotherapy, quality of life, and potential mechanisms of action. However, we still do not know the answers to a number of fundamental questions around best clinical practice, such as how much, how often and for how long to administer IVC to oncology patients. These questions point the way forward for both basic research and future clinical trials.