High-dose intravenous vitamin C, a promising multi-targeting agent in the treatment of cancer

Biotin-functionalized nanoparticles: an overview of recent trends in cancer detection

Electrochemical bio-sensing is a potent and efficient method for converting various biological recognition events into voltage, current, and impedance electrical signals. Biochemical sensors are now a common part of medical applications, such as detecting blood glucose levels, detecting food pathogens, and detecting specific cancers. As an exciting feature, bio-affinity couples, such as proteins with aptamers, ligands, paired nucleotides, and antibodies with antigens, are commonly used as bio-sensitive elements in electrochemical biosensors. Biotin-avidin interactions have been utilized for various purposes in recent years, such as targeting drugs, diagnosing clinically, labeling immunologically, biotechnology, biomedical engineering, and separating or purifying biomolecular compounds. The interaction between biotin and avidin is widely regarded as one of the most robust and reliable noncovalent interactions due to its high bi-affinity and ability to remain selective and accurate under various reaction conditions and bio-molecular attachments. More recently, there have been numerous attempts to develop electrochemical sensors to sense circulating cancer cells and the measurement of intracellular levels of protein thiols, formaldehyde, vitamin-targeted polymers, huwentoxin-I, anti-human antibodies, and a variety of tumor markers (including alpha-fetoprotein, epidermal growth factor receptor, prostate-specific Ag, carcinoembryonic Ag, cancer antigen 125, cancer antigen 15-3, etc.). Still, the non-specific binding of biotin to endogenous biotin-binding proteins present in biological samples can result in false-positive signals and hinder the accurate detection of cancer biomarkers. This review summarizes various categories of biotin-functional nanoparticles designed to detect such biomarkers and highlights some challenges in using them as diagnostic tools.

Hemolysis attributed to high dose vitamin C: Two case reports

BACKGROUND

High-dose vitamin C treatment (HVCT) can reduce the adverse effect of chemotherapy and enhance the effect of antitumor therapy, which has been considered one of the safest alternative treatments. However, the severity of its adverse effects may have been underestimated. The most serious adverse effect is hemolysis, which may result in acute kidney injury or death. Although glucose-6-phosphate dehydrogenase (G6PD) deficiency is considered to be the main cause, the probability and pathological mechanism are not completely understood, leading to a lack of effective and standardized treatment methods.

CASE SUMMARY

Two patients with colorectal cancer developed hemolytic anemia after using 1 g/kg HVCT. In contrast to previous cases, the lowest hemoglobin level in the two cases was < 50 g/L, which was lower than previously reported. This may be because Case 1 had chronic hepatitis B for many years, which caused abnormal liver reserve function, and Case 2 had grade II bone marrow suppression. Both patients improved and were discharged after blood replacement therapy. Our cases had the most severe degree of hemolysis but the best prognosis, suggesting that our treatment may be helpful for rescue of drug-induced hemolysis. This is the first review of the literature on hemolysis caused by HVCT, and we found that all patients with G6PD deficiency developed hemolysis after HVCT.

CONCLUSION

G6PD deficiency should be considered as a contraindication to HVCT, and it is not recommended for patients with bone marrow suppression, moderate-to-severe anemia, hematopoietic abnormalities, or abnormal liver and kidney function. Early blood purification and steroid therapy may avoid acute kidney injury or death caused by HVCT-related hemolytic anemia.

Review of the Potential Role of Ascorbate in the Prevention and Treatment of Gynecological Cancers

Ascorbate (vitamin C) is an essential vitamin for the human body and participates in various physiological processes as an important coenzyme and antioxidant. Furthermore, the role of ascorbate in the prevention and treatment of cancer including gynecological cancer has gained much more interest recently. The bioavailability and certain biological functions of ascorbate are distinct in males versus females due to differences in lean body mass, sex hormones, and lifestyle factors. Despite epidemiological evidence that ascorbate-rich foods and ascorbate plasma concentrations are inversely related to cancer risk, ascorbate has not demonstrated a significant protective effect in patients with gynecological cancers. Adequate ascorbate intake may have the potential to reduce the risk of human papillomavirus (HPV) infection and high-risk HPV persistence status. High-dose ascorbate exerts antitumor activity and synergizes with chemotherapeutic agents in preclinical cancer models of gynecological cancer. In this review, we provide evidence for the biological activity of ascorbate in females and discuss the potential role of ascorbate in the prevention and treatment of ovarian, endometrial, and cervical cancers.

Joint multi-omics discriminant analysis with consistent representation learning using PANDA

Integrative multi-omics analysis provides deeper insight and enables better and more realistic modeling of the underlying biology and causes of diseases than does single omics analysis. Although several integrative multi-omics analysis methods have been proposed and demonstrated promising results in integrating distinct omics datasets, inconsistent distribution of the different omics data, which is caused by technology variations, poses a challenge for paired integrative multi-omics methods. In addition, the existing discriminant analysis-based integrative methods do not effectively exploit correlation and consistent discriminant structures, necessitating a compromise between correlation and discrimination in using these methods. Herein we present PAN-omics Discriminant Analysis (PANDA), a joint discriminant analysis method that seeks omics-specific discriminant common spaces by jointly learning consistent discriminant latent representations for each omics. PANDA jointly maximizes between-class and minimizes within-class omics variations in a common space and simultaneously models the relationships among omics at the consistency representation and cross-omics correlation levels, overcoming the need for compromise between discrimination and correlation as with the existing integrative multi-omics methods. Because of the consistency representation learning incorporated into the objective function of PANDA, this method seeks a common discriminant space to minimize the differences in distributions among omics, can lead to a more robust latent representations than other methods, and is against the inconsistency of the different omics. We compared PANDA to 10 other state-of-the-art multi-omics data integration methods using both simulated and real-world multi-omics datasets and found that PANDA consistently outperformed them while providing meaningful discriminant latent representations. PANDA is implemented using both R and MATLAB, with codes available at https://github.com/WuLabMDA/PANDA.

Network pharmacology and molecular docking technology for exploring the effect and mechanism of high-dose vitamin c on ferroptosis of tumor cells: A review

To investigate the mechanism by which high-dose vitamin C (HVC) promotes ferroptosis in tumor cells via network pharmacology, vitamin C-related and ferroptosis-related targets were obtained from the PharmMapper and GeneCards databases, respectively, and their common targets were compared using the Venn diagram. Common targets were imported into the STRING database for protein-protein interaction analysis, and core targets were defined. Core targets were enriched for Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways using the R language packages. A map of the core target-based interaction network and a map of the mechanism by which HVC regulates ferroptosis were constructed. A total of 238 vitamin C-related and 721 ferroptosis-related targets were identified, of which 21 targets were common to both. Furthermore, ALDOA, AHCY, LDHB, HSPA8, LGALS3, and GSTP1 were identified as core targets. GO enrichment analysis suggested that the main biological processes included the extrinsic apoptotic signaling pathway and pyruvate metabolic process. KEGG enrichment analysis suggested that HVC regulates ferroptosis mainly through the amino acid and carbohydrate metabolic pathways. The targets were validated by molecular docking. In conclusion, HVC may promote ferroptosis in tumor cells by regulating metabolic pathways, and there is a synergistic effect between HVC and type I ferroptosis inducers. Glycolysis-dependent tumors may be beneficial for HVC therapy. Our study provides a reference for further clinical studies on HVC antitumor therapy.

Steady-State Delivery and Chemical Modification of Food Nutrients to Improve Cancer Intervention Ability

Cancer is a crucial global health problem, and prevention is an important strategy to reduce the burden of the disease. Daily diet is the key modifiable risk factor for cancer, and an increasing body of evidence suggests that specific nutrients in foods may have a preventive effect against cancer. This review summarizes the current evidence on the role of nutrients from foods in cancer intervention. It discusses the potential mechanisms of action of various dietary components, including phytochemicals, vitamins, minerals, and fiber. The findings of epidemiological and clinical studies on their association with cancer risk are highlighted. The foods are rich in bioactive compounds such as carotenoids, flavonoids, and ω-3 fatty acids, which have been proven to have anticancer properties. The effects of steady-state delivery and chemical modification of these food's bioactive components on anticancer and intervention are summarized. Future research should focus on identifying the specific bioactive compounds in foods responsible for their intervention effects and exploring the potential synergistic effects of combining different nutrients in foods. Dietary interventions that incorporate multiple nutrients and whole foods may hold promise for reducing the risk of cancer and improving overall health.

Ascorbic acid as a modulator of inflammatory response against Candida albicans

Aim: To evaluate the behavior of oral keratinocytes in the presence of Vitamin C (Vit C) and its anti-inflammatory potential. Materials & methods: Oral keratinocytes were initially exposed to 0.1-2.5 mM of Vit C and the metabolic activity and cell migration were evaluated using MTS assay and Ibidi culture inserts, respectively. After, the cells were challenged with Candida albicans and inflammatory markers were analyzed by qPCR. Results: The treatment was not cytotoxic, and the highest concentrations increased the metabolic activity at 24 h. Vit C delayed the cell migration at 48 and 72 h. Interestingly, it downregulated the genes IL-8 and IL-1β. Conclusion: Vit C could be an interesting adjuvant to anti-fungal treatment due to its anti-inflammatory potential.

Empowering γδ T-cell functionality with vitamin C

Vitamin C (ascorbic acid) is a potent antioxidant and a cofactor for various enzymes including histone demethylases and methylcytosine dioxygenases. Vitamin C also exerts direct cytotoxicity toward selected tumor cells including colorectal carcinoma. Moreover, vitamin C has been shown to impact immune cell differentiation at various levels including maturation and/or functionality of T cells and their progenitors, dendritic cells, B cells, and NK cells. γδ T cells have recently attracted great interest as effector cells for cell-based cancer immunotherapy, due to their HLA-independent recognition of a large variety of tumor cells. While γδ T cells can thus be also applied as an allogeneic off-the-shelf product, it is obvious that the effector function of γδ T cells needs to be optimized to ensure the best possible clinical efficacy. Here we review the immunomodulatory mechanisms of vitamin C with a special focus on how vitamin C enhances the effector function of γδ T cells. We also discuss future directions of how vitamin C can be used in the clinical setting to boost the efficacy of adoptive cell therapies.

High-dose ascorbate exerts anti-tumor activities and improves inhibitory effect of carboplatin through the pro-oxidant function pathway in uterine serous carcinoma cell lines

OBJECTIVE

Uterine serous carcinoma is a highly aggressive non-endometrioid subtype of endometrial cancer with poor survival rates overall, creating a strong need for new therapeutic strategies to improve outcomes. High-dose ascorbate (vitamin C) has been shown to inhibit cell proliferation and tumor growth in multiple preclinical models and has shown promising anti-tumor activity in combination with chemotherapy, with a favorable safety profile. We aimed to study the anti-tumor effects of ascorbate and its synergistic effect with carboplatin on uterine serous carcinoma cells.

METHODS

Cell proliferation was evaluated by MTT and colony formation assays in ARK1, ARK2 and SPEC2 cells. Cellular stress, antioxidant ability, cleaved caspase 3 activity and adhesion were measured by ELISA assays. Cell cycle was detected by Cellometer. Invasion was measured using a wound healing assay. Changes in protein expression were determined by Western immunoblotting.

RESULTS

High-dose ascorbate significantly inhibited cell proliferation, caused cell cycle arrest, induced cellular stress, and apoptosis, increased DNA damage, and suppressed cell invasion in ARK1 and SPEC2 cells. Treatment of both cells with 1 mM N-acetylcysteine reversed ascorbate-induced apoptosis and inhibition of cell proliferation. The combination of ascorbate and carboplatin produced significant synergistic effects in inhibiting cell proliferation and invasion, inducing cellular stress, causing DNA damage, and enhancing cleaved caspase 3 levels compared to each compound alone in both cells.

CONCLUSIONS

Ascorbate has potent antitumor activity and acts synergistically with carboplatin through its pro-oxidant effects. Clinical trials of ascorbate combined with carboplatin as adjuvant treatment of uterine serous carcinoma are worth exploring.

Neuroprotection Role of Vitamin C by Upregulating Glutamate Transporter-1 in Auditory Cortex of Noise-Induced Tinnitus Animal Model

Vitamin C (Vc) plays a pivotal role in a series of pathological processes, such as tumors, immune diseases, and neurological disorders. However, its therapeutic potential for tinnitus management remains unclear. In this study, we find that Vc relieves tinnitus in noise-exposed rats. In the 7-day therapy groups, spontaneous firing rate (SFR) increases from 1.17 ± 0.10 Hz to 1.77 ± 0.15 Hz after noise exposure. Vc effectively reduces the elevated SFR to 0.99 ± 0.07 and 0.55 ± 0.05 Hz at different doses. The glutamate level in auditory cortex of noise-exposed rats (3.78 ± 0.42 μM) increases relative to that in the control group (1.34 ± 0.22 μM). High doses of Vc (500 mg/kg/day) effectively reduce the elevated glutamate levels (1.49 ± 0.28 μM). Mechanistic studies show that the expression of glutamate transporter 1 (GLT-1) is impaired following noise exposure and that Vc treatment effectively restores GLT-1 expression in the auditory cortex. Meanwhile, the GLT-1 inhibitor, dl-threo-beta-benzyloxyaspartic acid (dl-TBOA), invalidates the protection role of Vc. Our finding shows that Vc substantially enhances glutamate clearance by upregulating GLT-1 and consequently alleviates noise-induced tinnitus. This study provides valuable insight into a novel biological target for the development of therapeutic interventions that may prevent the onset of tinnitus.

Multiple Physiological and Biochemical Functions of Ascorbic Acid in Plant Growth, Development, and Abiotic Stress Response

Ascorbic acid (AsA) is an important nutrient for human health and disease cures, and it is also a crucial indicator for the quality of fruit and vegetables. As a reductant, AsA plays a pivotal role in maintaining the intracellular redox balance throughout all the stages of plant growth and development, fruit ripening, and abiotic stress responses. In recent years, the de novo synthesis and regulation at the transcriptional level and post-transcriptional level of AsA in plants have been studied relatively thoroughly. However, a comprehensive and systematic summary about AsA-involved biochemical pathways, as well as AsA's physiological functions in plants, is still lacking. In this review, we summarize and discuss the multiple physiological and biochemical functions of AsA in plants, including its involvement as a cofactor, substrate, antioxidant, and pro-oxidant. This review will help to facilitate a better understanding of the multiple functions of AsA in plant cells, as well as provide information on how to utilize AsA more efficiently by using modern molecular biology methods.

Natural products for gastric carcinoma prevention and treatment: Focus on their antioxidant stress actions in the Correa's cascade

BACKGROUND

Correa's cascade is a pathological process beginning from gastritis to gastric precancerous lesions, and finally to gastric carcinoma (GC). While the pathogenesis of GC remains unclear, oxidative stress plays a prominent role throughout the entire Correa's cascade process. Studies have shown that some natural products (NPs) could halt and even reverse the development of the Correa's cascade by targeting oxidative stress.

METHODS

To review the effects and mechanism by which NPs inhibit the Correa's cascade through targeting oxidative stress, data were collected from PubMed, Embase, Web of Science, ScienceDirect, and China National Knowledge Infrastructure databases from initial establishment to April 2023. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as terpenoid, polyphenols and alkaloids, exert multistep antioxidant stress effects on the Correa's cascade. These effects include preventing gastric mucosal inflammation (stage 1), reversing gastric precancerous lesions (stage 2), and inhibiting gastric carcinoma (stage 3). NPs can directly impact the conversion of gastritis to GC by targeting oxidative stress and modulating signaling pathways involving IL-8, Nrf2, TNF-α, NF-κB, and ROS/MAPK. Among which polyphenols have been studied more and are of high research value.

CONCLUSIONS

NPs display a beneficial multi-step action on the Correa's cascade, and have potential value for clinical application in the prevention and treatment of gastric cancer by regulating the level of oxidative stress.

Therapeutic potential role of vitamin C in prevention and control of heart transplant rejection and cardiac allograft vasculopathy. A need for consideration

The burden of cardiovascular diseases is rising rapidly globally. Heart transplant is one of the most last resort medical option for patients with heart failure. Unfortunately, this surgical intervention is associated with several serious complications including heart transplant rejection (HTR) and Cardiac Allograft Vasculopathy (CAV) which can manifest just within few years' posttransplant. These complications affect significantly the prognosis and quality of life among postheart transplant patients. Several medications including immunosuppressant, antibiotics, antihypertensive, and statins have been used during posttransplant care so as to address such complications. Unfortunately, most of those drugs are expensive and pose a number of serious side effects to the patients enough to compromise patients' quality of life too. Several studies on Vitamin C are therapeutically suggestive that it can be used during postheart transplant care with more cost-effective benefits with less and minimized side effects compared to the current drugs in place. It should be considered pharmacologically that Vitamin C has a great potential role clinically in prevention and control of HTR and CAV development. On the light of such findings as described above, we recommend more studies especially clinical trials and molecular studies to determine whether Vitamin C can be repositioned to replace or to be used along the current drug regimens used in postheart transplant care for prevention and control of HTR and CAV.

Ex Vivo Anti-Leukemic Effect of Exosome-like Grapefruit-Derived Nanovesicles from Organic Farming-The Potential Role of Ascorbic Acid

Citrus fruits are a natural source of ascorbic acid, and exosome-like nanovesicles obtained from these fruits contain measurable levels of ascorbic acid. We tested the ability of grapefruit-derived extracellular vesicles (EVs) to inhibit the growth of human leukemic cells and leukemic patient-derived bone marrow blasts. Transmission electron microscopy and nanoparticle tracking analysis (NTA) showed that the obtained EVs were homogeneous exosomes, defined as exosome-like plant-derived nanovesicles (ELPDNVs). The analysis of their content has shown measurable amounts of several molecules with potent antioxidant activity. ELPDNVs showed a time-dependent antiproliferative effect in both U937 and K562 leukemic cell lines, comparable with the effect of high-dosage ascorbic acid (2 mM). This result was confirmed by a clear decrease in the number of AML blasts induced by ELPDNVs, which did not affect the number of normal cells. ELPDNVs increased the ROS levels in both AML blast cells and U937 without affecting ROS storage in normal cells, and this effect was comparable to ascorbic acid (2 mM). With our study, we propose ELPDNVs from grapefruits as a combination/supporting therapy for human leukemias with the aim to improve the effectiveness of the current therapies.

Rowanberry-A Source of Bioactive Compounds and Their Biopharmaceutical Properties

After a period of intense development in the synthesis pharmaceutical industry, plants are making a comeback in the public focus as remedies or therapeutic adjuvants and in disease prevention and ensuring the wellbeing and equilibrium of the human body. Plants are being recommended more and more in alimentation, in their natural form, or as extracts, supplements or functional aliments. People, in general, are in search of new sources of nutrients and phytochemicals. As a result, scientific research turns to lesser known and used plants, among them being rowanberries, a species of fruit very rich in nutrients and underused due to their bitter astringent taste and a lack of knowledge regarding the beneficial effects of these fruit. Rowan fruits (rowanberries) are a rich source of vitamins, polysaccharides, organic acids and minerals. They are also a source of natural polyphenols, which are often correlated with the prevention and treatment of modern world diseases. This article presents the existing data regarding the chemical composition, active principles and biopharmaceutical properties of rowan fruits and the different opportunities for their usage.

Effect of Hydrogen Plasma Treatment on the Sensitivity of ZnO Based Electrochemical Non-Enzymatic Biosensor

Information on vitamin C-ascorbic acid (AA)-content is important as it facilitates the provision of dietary advice and strategies for the prevention and treatment of conditions associated with AA deficiency or excess. The methods of determining AA content include chromatographic techniques, spectrophotometry, and electrochemical methods of analysis. In the present work, an electrochemical enzyme-free ascorbic acid sensor for a neutral medium has been developed. The sensor is based on zinc oxide nanowire (ZnO NW) arrays synthesized via low-temperature chemical deposition (Chemical Bath Deposition) on the surface of an ITO substrate. The sensitivity of the electrochemical enzyme-free sensor was found to be dependent on the process treatments. The AA sensitivity values measured in a neutral PBS electrolyte were found to be 73, 44, and 92 µA mM-1 cm-2 for the ZnO NW-based sensors of the pristine, air-annealed (AT), and air-annealed followed by hydrogen plasma treatment (AT+PT), respectively. The simple H-plasma treatment of ZnO nanowire arrays synthesized via low-temperature chemical deposition has been shown to be an effective process step to produce an enzyme-free sensor for biological molecules in a neutral electrolyte for applications in health care and biomedical safety.

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).

Nanoparticle-Based Antioxidants in Stress Signaling and Programmed Cell Death in Breast Cancer Treatment

Breast cancer (BC) is a complex and heterogeneous disease, and oxidative stress is a hallmark of BC. Oxidative stress is characterized by an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense mechanisms. ROS has been implicated in BC development and progression by inducing DNA damage, inflammation, and angiogenesis. Antioxidants have been shown to scavenge ROS and protect cells from oxidative damage, thereby regulating signaling pathways involved in cell growth, survival, and death. Plants contain antioxidants like ascorbic acid, tocopherols, carotenoids, and flavonoids, which have been found to regulate stress signaling and PCD in BC. Combining different antioxidants has shown promise in enhancing the effectiveness of BC treatment. Antioxidant nanoparticles, when loaded with antioxidants, can effectively target breast cancer cells and enhance their cellular uptake. Notably, these nanoparticles have shown promising results in inducing PCD and sensitizing breast cancer cells to chemotherapy, even in cases where resistance is observed. This review aims to explore how nanotechnology can modulate stress signaling and PCD in breast cancer. By summarizing current research, it underscores the potential of nanotechnology in enhancing antioxidant properties for the treatment of breast cancer.

Lysine vitcylation is a novel vitamin C-derived protein modification that enhances STAT1-mediated immune response

Vitamin C (vitC) is a vital nutrient for health and also used as a therapeutic agent in diseases such as cancer. However, the mechanisms underlying vitC's effects remain elusive. Here we report that vitC directly modifies lysine without enzymes to form vitcyl-lysine, termed "vitcylation", in a dose-, pH-, and sequence-dependent manner across diverse proteins in cells. We further discover that vitC vitcylates K298 site of STAT1, which impairs its interaction with the phosphatase PTPN2, preventing STAT1 Y701 dephosphorylation and leading to increased STAT1-mediated IFN pathway activation in tumor cells. As a result, these cells have increased MHC/HLA class-I expression and activate immune cells in co-cultures. Tumors collected from vitC-treated tumor-bearing mice have enhanced vitcylation, STAT1 phosphorylation and antigen presentation. The identification of vitcylation as a novel PTM and the characterization of its effect in tumor cells opens a new avenue for understanding vitC in cellular processes, disease mechanisms, and therapeutics.

Efficient production of 2-keto-L-gulonic acid from D-glucose in Gluconobacter oxydans ATCC9937 by mining key enzyme and transporter

Direct production of 2-keto-L-gulonic acid (2-KLG, the precursor of vitamin C) from D-glucose through 2,5-diketo-D-gluconic acid (2,5-DKG) is a promising alternative route. To explore the pathway of producing 2-KLG from D-glucose, Gluconobacter oxydans ATCC9937 was selected as a chassis strain. It was found that the chassis strain naturally has the ability to synthesize 2-KLG from D-glucose, and a new 2,5-DKG reductase (DKGR) was found on its genome. Several major issues limiting production were identified, including the insufficient catalytic capacity of DKGR, poor transmembrane movement of 2,5-DKG and imbalanced D-glucose consumption flux inside and outside of the host strain cells. By identifying novel DKGR and 2,5-DKG transporter, the whole 2-KLG biosynthesis pathway was systematically enhanced by balancing intracellular and extracellular D-glucose metabolic flux. The engineered strain produced 30.5 g/L 2-KLG with a conversion ratio of 39.0%. The results pave the way for a more economical large-scale fermentation process for vitamin C.

Oxidative stress enhances the therapeutic action of a respiratory inhibitor in MYC-driven lymphoma

MYC is a key oncogenic driver in multiple tumor types, but concomitantly endows cancer cells with a series of vulnerabilities that provide opportunities for targeted pharmacological intervention. For example, drugs that suppress mitochondrial respiration selectively kill MYC-overexpressing cells. Here, we unravel the mechanistic basis for this synthetic lethal interaction and exploit it to improve the anticancer effects of the respiratory complex I inhibitor IACS-010759. In a B-lymphoid cell line, ectopic MYC activity and treatment with IACS-010759 added up to induce oxidative stress, with consequent depletion of reduced glutathione and lethal disruption of redox homeostasis. This effect could be enhanced either with inhibitors of NADPH production through the pentose phosphate pathway, or with ascorbate (vitamin C), known to act as a pro-oxidant at high doses. In these conditions, ascorbate synergized with IACS-010759 to kill MYC-overexpressing cells in vitro and reinforced its therapeutic action against human B-cell lymphoma xenografts. Hence, complex I inhibition and high-dose ascorbate might improve the outcome of patients affected by high-grade lymphomas and potentially other MYC-driven cancers.

Development and Evaluation of an Innovative Approach Using Niosomes Based Polymeric Microneedles to Deliver Dual Antioxidant Drugs

Ascorbic acid (AA) and caffeine (CAFF) work to protect cells from ultraviolet (UV) radiation and slow down the photoaging process of the skin. However, cosmetic application of AA and CAFF is limited due to poor penetration across the skin and rapid oxidation of AA. The aim of this study was to design and evaluate the dermal delivery of dual antioxidants utilizing microneedles (MNs) loaded with AA and CAFF niosomes. The niosomal nanovesicles were prepared using the thin film method and had particle sizes ranging from 130.6-411.2 nm and a negative Zeta potential of around -35 mV. The niosomal formulation was then combined with polyvinylpyrrolidone (PVP) and polyethylene glycol 400 (PEG 400) to create an aqueous polymer solution. The best skin deposition of AA and CAFF was achieved with the formulation containing 5% PEG 400 (M3) and PVP. Furthermore, the role of AA and CAFF as antioxidants in preventing cancer formation has been well-established. Here we validated the antioxidant properties of ascorbic acid (AA) and caffeine (CAFF) in a novel niosomal formulation referred to as M3 by testing its ability to prevent H₂O₂-indued cell damage and apoptosis in MCF-7 breast cancer cells. Results showed that M3 was able to shield MCF-7 cells from H₂O₂ induced damage at concentrations below 2.1 µg/mL for AA and 1.05 µg/mL for CAFF, and also exhibited anticancer effects at higher concentrations of 210 µg/mL for AA and 105 µg/mL. The formulations were stable for two months at room temperature in terms of moisture and drug content. The use of MNs and niosomal carriers could be a promising approach for dermal delivery of hydrophilic drugs like AA and CAFF.

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.

Overcoming EGFR Resistance in Metastatic Colorectal Cancer Using Vitamin C: A Review

Targeted monoclonal antibody therapy against Epidermal Growth Factor Receptor (EGFR) is a leading treatment modality against metastatic colorectal cancer (mCRC). However, with the emergence of KRAS and BRAF mutations, resistance was inevitable. Cells harboring these mutations overexpress Glucose Transporter 1 (GLUT1) and sodium-dependent vitamin C transporter 2 (SVCT2), which enables intracellular vitamin C transport, leading to reactive oxygen species generation and finally cell death. Therefore, high dose vitamin C is proposed to overcome this resistance. A comprehensive search strategy was adopted using Pubmed and MEDLINE databases (up to 11 August 2022). There are not enough randomized clinical trials to support its use in the clinical management of mCRC, except for a subgroup analysis from a phase III study. High dose vitamin C shows a promising role in overcoming EGFR resistance in mCRC with wild KRAS mutation with resistance to anti-epidermal growth factor inhibitors and in patients with KRAS and BRAF mutations.

The Combined Administration of Vitamin C and Copper Induces a Systemic Oxidative Stress and Kidney Injury

Vitamin C (ascorbic acid; AA) and copper (Cu²⁺) are well used supplements with many health-promoting actions. However, when they are used in combination, the Fenton reaction occurs, leading to the formation of highly reactive hydroxyl radicals. Given that kidney is vulnerable to many toxicants including free radicals, we speculated that the in vivo administration of AA plus Cu²⁺ may cause oxidative kidney injury. The purpose of this study was to address this possibility. Mice were administered with AA and Cu²⁺, alone or in combination, via oral gavage once a day for various periods. Changes in the systemic oxidative status, as well renal structure and functions, were examined. The administration of AA plus Cu²⁺ elevated protein oxidation in serum, intestine, bladder, and kidney, as evidenced by the increased sulfenic acid formation and decreased level of free sulfhydryl groups (-SH). The systemic oxidative stress induced by AA plus Cu²⁺ was associated with a significant loss of renal function and structure, as indicated by the increased blood urea nitrogen (BUN), creatinine and urinary proteins, as well as glomerular and tubular cell injury. These effects of AA and Cu²⁺ were only observed when used in combination, and could be entirely prevented by thiol antioxidant NAC. Further analysis using cultured renal tubular epithelial cells revealed that AA plus Cu²⁺ caused cellular protein oxidation and cell death, which could be abolished by NAC and catalase. Moreover, coincubation of AA and Cu²⁺ led to H₂O₂ production. Collectively, our study revealed that a combined administration of AA and Cu²⁺ resulted in systemic oxidative stress and renal cell injury. As health-promoting supplements, AA and Cu²⁺ should not be used together.

Current research trends, hotspots, and frontiers of medical nutrition therapy on cancer: a bibliometric analysis

Background

There is a high prevalence of malnutrition in cancer patients, which seriously affects the anti-cancer therapy effect and outcomes, causing a huge disease burden worldwide. Appropriate nutritional support is important for cancer prevention and control. The aim of this study was to explore the development trends, hotspots, and frontiers of Medical Nutrition Therapy (MNT) on Cancer from a bibliometric perspective, and provide new insights for future research and clinic practices.

Methods

The global literature of MNT on Cancer published between 1975 and 2022 were searched in the Web of Science Core Collection Database (WOSCC). After refining the data, descriptive analysis and data visualization were performed with bibliometric tools (CiteSpace, VOSviewer, and R package "bibliometrix").

Results

A total of 10,339 documents with a timespan from 1982 to 2022 were included in this study. The number of documents had increased continuously over the past 40 years, especially with a steep rise from 2016 to 2022. The majority of scientific production outputs were from the United States, which had the most core research institutions and authors. The published documents could be clustered into three themes respectively labeled by terms "double-blind", "cancer" and "quality-of-life". "gastric cancer", "outcome", "inflammation", "sarcopenia" and "exercise" were the most prominent keywords in recent years. "breast-cancer", "colorectal-cancer", "expression", "risk", "in-vitro", "quality-of-life", "cancer" and "life" might represent the newly emerged topics.

Conclusions

There were a good research foundation and reasonable disciplinary structure in the field of medical nutrition therapy for cancer at present. The core research team was mainly located in the United States, England, and other developed countries. According to the current trends in publications, more articles shall be published in the future. Nutritional metabolism, malnutrition risk, and the impact of nutritional therapy on prognosis might be research hotspots. In particular, it was important to focus on specific cancer, such as breast cancer, colorectal cancer, and gastric cancer, which might be the frontiers.

Vitamin C supplementation for diabetes management: A comprehensive narrative review

Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.

Tracing the electron flow in redox metabolism: The appropriate distribution of electrons is essential to maintain redox balance in cancer cells

Cancer cells are characterized by sustained proliferation, which requires a huge demand of fuels to support energy production and biosynthesis. Energy is produced by the oxidation of the fuels during catabolism, and biosynthesis is achieved by the reduction of smaller units or precursors. Therefore, the oxidation-reduction (redox) reactions in cancer cells are more active compared to those in the normal counterparts. The higher activity of redox metabolism also induces a more severe oxidative stress, raising the question of how cancer cells maintain the redox balance. In this review, we overview the redox metabolism of cancer cells in an electron-tracing view. The electrons are derived from the nutrients in the tumor microenvironment and released during catabolism. Most of the electrons are transferred to NAD(P) system and then directed to four destinations: energy production, ROS generation, reductive biosynthesis and antioxidant system. The appropriate distribution of these electrons achieved by the function of redox regulation network is essential to maintain redox homeostasis in cancer cells. Interfering with the electron distribution and disrupting redox balance by targeting the redox regulation network may provide therapeutic implications for cancer treatment.

Antiangiogenic Activity of Quinine Alone and in Combination with vitamin C in both ex vivo and in vivo Assays

BACKGROUND

Angiogenesis is the process of vascularization from preexisting blood vessels. It is essential for many physiological and pathological processes. Quinine is an anti-malarial agent belongs to the quinoline alkaloid that can inhibit angiogenesis. Vitamin C is also an important antioxidant and has been shown to reduce angiogenesis in tumor.

OBJECTIVE

The study was aimed at investigating the effect of quinine alone and in combination with vitamin C on angiogenesis process.

MATERIALS AND METHODS

12 to 14 weeks old male albino rats were used for the study. Quinine was prepared by dissolving in DMSO and was serially diluted. The rat aorta ring assay was employed to investigate the antiangiogenic effect of quinine ex vivo. An in vivo chorioallantoic membrane (CAM) assay was used to measure the blood vessels inhibition zone by quinine. The zone of inhibition was calculated as the mean inhibition area of a blood vessel in mm±SD.The obtained data were statistically analyzed.

RESULTS

The results revealed that quinine has a significant dose-dependent inhibition effect on the growth of blood vessels by 98% ± 0.07 in concentration 100µg/ml when compared to the negative control. moreover, the inhibition of blood vessels growth as a measure of the antiangiogenic activity of quinine in combination with vitamin C shows a synergistic effect when the concentration that inhibit 50% of blood vessels growth (IC50) which equals to 5.05 µg/ml resulted in 85% of growth inhibition when combined with IC50 of vitamin C which equals to 22..87µg/ml.

CONCLUSION

The findings suggest that the activity of quinine with vitamin C synergism can greatly lower blood vessels growth in rat aorta rings and CAM assays. Quininehas an inhibitory effect on tumor and can be utilized as an antiangiogenic agent alone or in combination with vitamin C.

Integrative Approaches to the Treatment of Cancer

A significant proportion of cancer patients use forms of complementary medicine or therapies. An integrative approach to cancer management combines conventional medicine with evidence-based complementary medicines/therapies and lifestyle interventions, for the treatment and prevention of disease and the optimisation of health. Its basis is a holistic one; to treat the whole person, not just the disease. It makes use of adjunct technologies which may assist the clinician in diagnosis of early carcinogenesis and monitoring of treatment effectiveness. Many factors contribute to the development of cancer including some which are largely modifiable by the patient and which oncologists may be in a position to advise on, such as stress, poor nutrition, lack of physical activity, poor sleep, and Vitamin D deficiency. An integrative approach to addressing these factors may contribute to better overall health of the patient and better outcomes. Evidence-based complementary medicine approaches include the use of supplements, herbal medicine, various practices that reduce stress, and physical therapies. Individualised to the patient, these can also help address the symptoms and signs associated with cancer and its orthodox treatment.

Interactions between Dietary Micronutrients, Composition of the Microbiome and Efficacy of Immunotherapy in Cancer Patients

The effectiveness of immunotherapy in cancer patients depends on the activity of the host's immune system. The intestinal microbiome is a proven immune system modulator, which plays an important role in the development of many cancers and may affect the effectiveness of anti-cancer therapy. The richness of certain bacteria in the gut microbiome (e.g., Bifidobacterium spp., Akkermanisa muciniphila and Enterococcus hire) improves anti-tumor specific immunity and the response to anti-PD-1 or anti-PD-L1 immunotherapy by activating antigen-presenting cells and cytotoxic T cells within the tumor. Moreover, micronutrients affect directly the activities of the immune system or regulate their function by influencing the composition of the microbiome. Therefore, micronutrients can significantly influence the effectiveness of immunotherapy and the development of immunorelated adverse events. In this review, we describe the relationship between the supply of microelements and the abundance of various bacteria in the intestinal microbiome and the effectiveness of immunotherapy in cancer patients. We also point to the function of the immune system in the case of shifts in the composition of the microbiome and disturbances in the supply of microelements. This may in the future become a therapeutic target supporting the effects of immunotherapy in cancer patients.

The Self-Administered Use of Complementary and Alternative Medicine (CAM) Supplements and Antioxidants in Cancer Therapy and the Critical Role of Nrf-2-A Systematic Review

Complementary and alternative medicine (CAM) supplements are widely used by cancer patients. Dietary supplements, vitamins and minerals, herbal remedies, and antioxidants are especially popular. In a systematic literature review, 37 studies, each including more than 1000 participants, on CAM, dietary supplement, and vitamin use among cancer patients were identified. Accordingly, cancer patients use antioxidants such as vitamin C (from 2.6% (United Kingdom) to 41.6% (United States)) and vitamin E (from 2.9% (China) to 48% (United States)). Dietary supplements and vitamins are taken for different reasons, but often during conventional cancer treatment involving chemotherapy or radiotherapy and in a self-decided manner without seeking medical advice from healthcare professionals. Drug-drug interactions with dietary supplements or vitamins involving multiple signaling pathways are well described. Since most of the anticancer drugs generate reactive oxygen species (ROS), an adaptive stress response of healthy and malignant cells, mainly driven by the Nrf-2-Keap I network, can be observed. On the one hand, healthy cells should be protected from ROS-overproducing chemotherapy and radiotherapy; on the other hand, ROS production in cancer cells is a "desirable side effect" during anticancer drug treatment. We here describe the paradoxical use of antioxidants and supplements during cancer therapy, possible interactions with anticancer drugs, and the involvement of the Nrf-2 transcription factor.

Antioxidants in brain tumors: current therapeutic significance and future prospects

Brain cancer is regarded among the deadliest forms of cancer worldwide. The distinct tumor microenvironment and inherent characteristics of brain tumor cells virtually render them resistant to the majority of conventional and advanced therapies. Oxidative stress (OS) is a key disruptor of normal brain homeostasis and is involved in carcinogenesis of different forms of brain cancers. Thus, antioxidants may inhibit tumorigenesis by preventing OS induced by various oncogenic factors. Antioxidants are hypothesized to inhibit cancer initiation by endorsing DNA repair and suppressing cancer progression by creating an energy crisis for preneoplastic cells, resulting in antiproliferative effects. These effects are referred to as chemopreventive effects mediated by an antioxidant mechanism. In addition, antioxidants minimize chemotherapy-induced nonspecific organ toxicity and prolong survival. Antioxidants also support the prooxidant chemistry that demonstrate chemotherapeutic potential, particularly at high or pharmacological doses and trigger OS by promoting free radical production, which is essential for activating cell death pathways. A growing body of evidence also revealed the roles of exogenous antioxidants as adjuvants and their ability to reverse chemoresistance. In this review, we explain the influences of different exogenous and endogenous antioxidants on brain cancers with reference to their chemopreventive and chemotherapeutic roles. The role of antioxidants on metabolic reprogramming and their influence on downstream signaling events induced by tumor suppressor gene mutations are critically discussed. Finally, the review hypothesized that both pro- and antioxidant roles are involved in the anticancer mechanisms of the antioxidant molecules by killing neoplastic cells and inhibiting tumor recurrence followed by conventional cancer treatments. The requirements of pro- and antioxidant effects of exogenous antioxidants in brain tumor treatment under different conditions are critically discussed along with the reasons behind the conflicting outcomes in different reports. Finally, we also mention the influencing factors that regulate the pharmacology of the exogenous antioxidants in brain cancer treatment. In conclusion, to achieve consistent clinical outcomes with antioxidant treatments in brain cancers, rigorous mechanistic studies are required with respect to the types, forms, and stages of brain tumors. The concomitant treatment regimens also need adequate consideration.

Diverse antitumor effects of ascorbic acid on cancer cells and the tumor microenvironment

Ascorbic acid has attracted substantial attention for its potential antitumor effects by acting as an antioxidant in vivo and as a cofactor in diverse enzymatic reactions. However, solid proof of its clinical efficacy against cancer and the mechanism behind its effect have not been established. Moreover, cancer forms cancer-specific microenvironments and interacts with various cells, such as cancer-associated fibroblasts (CAFs), to maintain cancer growth and progression; however, the effect of ascorbic acid on the cancer microenvironment is unclear. This review discusses the effects and mechanisms of ascorbic acid on cancer, including the role of ascorbic acid concentration. In addition, we present future perspectives on the effects of ascorbic acid on cancer cells and the CAF microenvironment. Ascorbic acid has a variety of effects, which contributes to the complexity of these effects. Oral administration of ascorbic acid results in low blood concentrations (&lt;0.2 mM) and acts as a cofactor for antioxidant effects, collagen secretion, and HIFα degradation. In contrast, intravenous treatment achieves large blood concentrations (&gt;1 mM) and has oxidative-promoting actions that exert anticancer effects via reactive oxygen species. Therefore, intravenous administration at high concentrations is required to achieve the desired effects on cancer cells during treatment. Partial data on the effect of ascorbic acid on fibroblasts indicate that it may also modulate collagen secretion in CAFs and impart tumor-suppressive effects. Thus, future studies should verify the effect of ascorbic acid on CAFs. The findings of this review can be used to guide further research and clinical trials.

5-methylcytosine turnover: Mechanisms and therapeutic implications in cancer

DNA methylation at the fifth position of cytosine (5mC) is one of the most studied epigenetic mechanisms essential for the control of gene expression and for many other biological processes including genomic imprinting, X chromosome inactivation and genome stability. Over the last years, accumulating evidence suggest that DNA methylation is a highly dynamic mechanism driven by a balance between methylation by DNMTs and TET-mediated demethylation processes. However, one of the main challenges is to understand the dynamics underlying steady state DNA methylation levels. In this review article, we give an overview of the latest advances highlighting DNA methylation as a dynamic cycling process with a continuous turnover of cytosine modifications. We describe the cooperative actions of DNMT and TET enzymes which combine with many additional parameters including chromatin environment and protein partners to govern 5mC turnover. We also discuss how mathematical models can be used to address variable methylation levels during development and explain cell-type epigenetic heterogeneity locally but also at the genome scale. Finally, we review the therapeutic implications of these discoveries with the use of both epigenetic clocks as predictors and the development of epidrugs that target the DNA methylation/demethylation machinery. Together, these discoveries unveil with unprecedented detail how dynamic is DNA methylation during development, underlying the establishment of heterogeneous DNA methylation landscapes which could be altered in aging, diseases and cancer.

Glucose transporters: Important regulators of endometrial cancer therapy sensitivity

Glucose is of great importance in cancer cellular metabolism. Working together with several glucose transporters (GLUTs), it provides enough energy for biological growth. The main glucose transporters in endometrial cancer (EC) are Class 1 (GLUTs 1–4) and Class 3 (GLUTs 6 and 8), and the overexpression of these GLUTs has been observed. Apart from providing abundant glucose uptake, these highly expressed GLUTs also participate in the activation of many crucial signaling pathways concerning the proliferation, angiogenesis, and metastasis of EC. In addition, overexpressed GLUTs may also cause endometrial cancer cells (ECCs) to be insensitive to hormone therapy or even resistant to radiotherapy and chemoradiotherapy. Therefore, GLUT inhibitors may hopefully become a sensitizer for EC precision-targeted therapies. This review aims to summarize the expression regulation, function, and therapy sensitivity of GLUTs in ECCs, aiming to provide a new clue for better diagnosis and treatment of EC.

Vitamin C Sensitizes Pancreatic Cancer Cells to Erastin-Induced Ferroptosis by Activating the AMPK/Nrf2/HMOX1 Pathway

Ferroptosis is a type of regulated cell death that displays a promising therapeutic pathway for drug-resistant tumor cells. However, some pancreatic cancer (PC) cells are less sensitive to erastin-induced ferroptosis, and normal pancreatic cells are susceptible to this newly discovered cell death. Therefore, there is an urgent need to find drugs to enhance the sensitivity of these PC cells to erastin while limiting side effects. Here, we found that the oxidized form of vitamin C-dehydroascorbic acid (DHA) can be transported into PC cells expressing high levels of GLUT1, resulting in ferroptosis. Moreover, pharmacological vitamin C combined with erastin can synergistically induce ferroptosis of PC cells involving glutathione (GSH) reduction and ferrous iron accumulation while inhibiting the cytotoxicity of normal cells. Mechanistically, as a direct system Xc^- inhibitor, erastin can directly suppress the synthesis of GSH, and the recycling of vitamin C and DHA is performed through GSH consumption, which is denoted as the classical mode. Furthermore, oxidative stress induced by erastin and vitamin C could enhance the expression of HMOX1 via the AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway to increase the labile iron level, which is named the nonclassical mode. In vivo experiments showed that erastin and vitamin C can significantly slow tumor growth in PC xenografts. In summary, the combination of erastin and vitamin C exerts a synergistic effect of classical and nonclassical modes to induce ferroptosis in PC cells, which may provide a promising therapeutic strategy for PC.

Vitamin C Deficiency in Patients With Acute Myeloid Leukemia

Vitamin C has been shown to play a significant role in suppressing progression of leukemia through epigenetic mechanisms. We aimed to study the role of vitamin C in acute myeloid leukemia (AML) biology and clinical course. To this purpose, the plasma levels of vitamin C at diagnosis in 62 patients with AML (including 5 cases with acute promyelocytic leukemia, APL),7 with myelodysplastic syndrome (MDS), and in 15 healthy donors (HDs) were studied. As controls, vitamins A and E levels were analysed. Expression of the main vitamin C transporters and of the TET2 enzyme were investigated by a specific RQ-PCR while cytoplasmic vitamin C concentration and its uptake were studied in mononuclear cells (MNCs), lymphocytes and blast cells purified from AML samples, and MNCs isolated from HDs. There were no significant differences in vitamin A and E serum levels between patients and HDs. Conversely, vitamin C concentration was significantly lower in AML as compared to HDs (p&lt;0.0001), inversely correlated with peripheral blast‐counts (p=0.029), significantly increased at the time of complete remission (CR) (p=0.04) and further decreased in resistant disease (p=0.002). Expression of the main vitamin C transporters SLC23A2, SLC2A1 and SLC2A3 was also significantly reduced in AML compared to HDs. In this line, cytoplasmic vitamin C levels were also significantly lower in AML-MNCs versus HDs, and in sorted blasts compared to normal lymphocytes in individual patients. No association was found between vitamin C plasma levels and the mutation profile of AML patients, as well as when considering cytogenetics or 2017 ELN risk stratification groups. Finally, vitamin C levels did not play a predictive role for overall or relapse-free survival. In conclusion, our study shows that vitamin C levels are significantly decreased in patients with AML at the time of initial diagnosis, further decrease during disease progression and return to normal upon achievement of CR. Correspondingly, low intracellular levels may mirror increased vitamin C metabolic consumption in proliferating AML cells.

The Variable Nature of Vitamin C—Does It Help When Dealing with Coronavirus?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still spreading worldwide. For this reason, new treatment methods are constantly being researched. Consequently, new and already-known preparations are being investigated to potentially reduce the severe course of coronavirus disease 2019 (COVID-19). SARS-CoV-2 infection induces the production of pro-inflammatory cytokines and acute serum biomarkers in the host organism. In addition to antiviral drugs, there are other substances being used in the treatment of COVID-19, e.g., those with antioxidant properties, such as vitamin C (VC). Exciting aspects of the use of VC in antiviral therapy are its antioxidant and pro-oxidative abilities. In this review, we summarized both the positive effects of using VC in treating infections caused by SARS-CoV-2 in the light of the available research. We have tried to answer the question as to whether the use of high doses of VC brings the expected benefits in the treatment of COVID-19 and whether such treatment is the correct therapeutic choice. Each case requires individual assessment to determine whether the positives outweigh the negatives, especially in the light of populational studies concerning the genetic differentiation of genes encoding the solute carriers responsible forVC adsorption. Few data are available on the influence of VC on the course of SARS-CoV-2 infection. Deducing from already-published data, high-dose intravenous vitamin C (HDIVC) does not significantly lower the mortality or length of hospitalization. However, some data prove, among other things, its impact on the serum levels of inflammatory markers. Finally, the non-positive effect of VC administration is mainly neutral, but the negative effect is that it can result in urinary stones or nephropathies.

Ascorbate as a Bioactive Compound in Cancer Therapy: The Old Classic Strikes Back

Cancer is a disease of high mortality, and its prevalence has increased steadily in the last few years. However, during the last decade, the development of modern chemotherapy schemes, new radiotherapy techniques, targeted therapies and immunotherapy has brought new hope in the treatment of these diseases. Unfortunately, cancer therapies are also associated with frequent and, sometimes, severe adverse events. Ascorbate (ascorbic acid or vitamin C) is a potent water-soluble antioxidant that is produced in most mammals but is not synthesised endogenously in humans, which lack enzymes for its synthesis. Ascorbate has antioxidant effects that correspond closely to the dose administered. Interestingly, this natural antioxidant induces oxidative stress when given intravenously at a high dose, a paradoxical effect due to its interactions with iron. Importantly, this deleterious property of ascorbate can result in increased cell death. Although, historically, ascorbate has been reported to exhibit anti-tumour properties, this effect has been questioned due to the lack of available mechanistic detail. Recently, new evidence has emerged implicating ferroptosis in several types of oxidative stress-mediated cell death, such as those associated with ischemia–reperfusion. This effect could be positively modulated by the interaction of iron and high ascorbate dosing, particularly in cell systems having a high mitotic index. In addition, it has been reported that ascorbate may behave as an adjuvant of favourable anti-tumour effects in cancer therapies such as radiotherapy, radio-chemotherapy, chemotherapy, immunotherapy, or even in monotherapy, as it facilitates tumour cell death through the generation of reactive oxygen species and ferroptosis. In this review, we provide evidence supporting the view that ascorbate should be revisited to develop novel, safe strategies in the treatment of cancer to achieve their application in human medicine.

Repurposing Vitamin C for Cancer Treatment: Focus on Targeting the Tumor Microenvironment

Simple Summary

The tumor microenvironment (TME) is a complicated network, and several promising TME-targeted therapies, such as immunotherapy and targeted therapies, are now facing problems over low response rates and drug resistance. Vitamin C (VitC) has been extensively studied as a dietary nutrient and multi-targeted natural drug for fighting against tumor cells. The focus has been recently on its crucial functions in the TME. Here, we discuss the potential mechanisms of VitC in several specialized microenvironments, characterize the current status of its preclinical and clinical applications, and offer suggestions for future studies. This article is intended to provide basic researchers and clinicians with a detailed picture of VitC targeting the tumor microenvironment.

Abstract

Based on the enhanced knowledge on the tumor microenvironment (TME), a more comprehensive treatment landscape for targeting the TME has emerged. This microenvironment provides multiple therapeutic targets due to its diverse characteristics, leading to numerous TME-targeted strategies. With multifaced activities targeting tumors and the TME, vitamin C is renown as a promising candidate for combination therapy. In this review, we present new advances in how vitamin C reshapes the TME in the immune, hypoxic, metabolic, acidic, neurological, mechanical, and microbial dimensions. These findings will open new possibilities for multiple therapeutic avenues in the fight against cancer. We also review the available preclinical and clinical evidence of vitamin C combined with established therapies, highlighting vitamin C as an adjuvant that can be exploited for novel therapeutics. Finally, we discuss unresolved questions and directions that merit further investigation.

Complementary and Alternative Therapies in Oncology

Cancer is the second leading cause of death worldwide, after cardiovascular diseases. Increasing patients’ awareness and providing easier access to public information result in greater interest in alternative anticancer or unproven supportive therapies. Fear of cancer and limited trust in the treating physician are also important reasons leading patients to seek these methods. Trust and good communication are essential to achieving truthful collaboration between physicians and patients. Given the popularity of CAM, better knowledge about these alternative practices may help oncologists discuss this issue with their patients. This article objectively reviews the most common unconventional therapies used by cancer patients.