Vitamin C: A stem cell promoter in cancer metastasis and immunotherapy

Biochemical mechanisms and molecular interactions of vitamins in cancer therapy

Recently, the potential role of vitamins in cancer therapy has attracted considerable research attention. However, the reported findings are inconsistent, with limited information on the biochemical and molecular interactions of different vitamins in various cancer cells. Importantly, the presence of vitamin receptors in tumor cells suggests that vitamins play a significant role in the molecular and biochemical interactions in cancers. Additionally, studies on the efficacy of vitamin supplementation and dosage levels on tumor progression and mortality risk have yielded inconsistent results. Notably, molecular and biochemical investigations have reported the function of vitamins in the proliferation, growth, and invasiveness of tumor cells, as well as in cell cycle arrest and inflammatory signaling. Additionally, different vitamins may regulate the cancer microenvironment by activating various molecular pathways. Vitamins significantly affect immunological function, antioxidant defense, inflammation, and epigenetic control, and can improve treatment outcomes by affecting cell behavior and combating stress and DNA damage. However, further research is necessary to confirm the efficacy of vitamins, establish ideal dosages, and develop effective cancer prevention and treatment plans. Individualized supplementation plans guided by medical knowledge are crucial to achieving optimal results in clinical and preclinical settings. In this review, we critically evaluated the effects of different vitamins on the risk and development of cancer. Additionally, we examined the potential of vitamin supplements to enhance the efficacy of drug therapy and counteract resistance mechanisms that often arise during cancer treatment.

Effective Targeting of Colorectal Cancer Stem Cells by Inducing Differentiation Mediated by Low-Dose Vitamin C via β-Catenin Retention in the Cell Membrane

Cancer stem cells (CSCs) are implicated as the underlying cause of tumor recurrence due to their refractoriness to conventional therapies. Targeting CSCs through novel approaches can hinder their survival and proliferation, potentially reducing the challenges associated with tumor relapse. Our previous study demonstrated that colorectal cancer stem cells (CR-CSCs) showed sensitivity to Vitamin C (Vit C), displaying a dose-responsive effect where low doses (2-10 µM) promoted cell proliferation while high doses induced cell death. In this study, we unraveled the mechanistic effects of low doses that, although induced proliferation, remarkably facilitated stemness reduction in HT-29 cell line-derived CR-CSCs. Our findings revealed that Vit C doses of 2 and 6 µM resulted in a reduction in stemness as evidenced by a reduced CD44+ cell population, representing CR-CSCs. The key finding was the remarkable increase in the expression of β-catenin protein following low-dose Vit C treatment, despite a reduction in stemness, accompanied by a mesenchymal to epithelial transition (MET). The sequestration of upregulated β-catenin via E-cadherin to the cell membrane was identified as a mechanism for reduced stemness, MET, and differentiation of CR-CSCs. Importantly, the epithelial phenotype induced by low-dose Vit C rendered CR-CSCs sensitive to conventional treatments, enhancing chemosensitivity to Cisplatin, Paclitaxel, and 5-Fluorouracil by 60%-90%. These findings suggest that low dose Vit C could serve as an adjuvant to conventional therapeutic strategies for targeting advanced colorectal cancer by sensitizing CR-CSCs to chemotherapy and potentially reducing tumor recurrence.

Ascorbic acid predominantly kills cancer stem cell-like cells in the hepatocellular carcinoma cell line Li-7 and is more effective at low cell density and in small spheroids

The development of therapies that target cancer stem cells (CSCs) is an important challenge in cancer research. The antioxidant system is enhanced in CSCs, which may lead to resistance to existing therapies. Ascorbic acid (AA) has the potential to act as both an antioxidant and a pro-oxidant agent, but its effects on CSCs are a subject of current research. Here, we investigated the effect of AA focusing specifically on CSCs with the hepatocellular carcinoma cell line Li-7. The Li-7 cell line is heterogenous consisting of CD166- and CD166+ cells; CD166- cells include CSC-like cells (CD13+CD166- cells) and CD13-CD166- cells that can revert to CD13+CD166- cells. The addition of AA to the culture medium caused cell death in both cell populations in CD166- cells in a concentration dependent manner. In contrast, AA administration had a limited effect on CD166+ non-CSC cells. The level of reactive oxygen species after AA treatment was elevated only in CD166- cells. The effect of AA only occurred at low cell densities in 2D and 3D cultures. In a mouse tumor model injected with Li-7 cells, intraperitoneal administration of AA failed to prevent tumor formation but appeared to delay tumor growth. Our findings shed light on why AA administration has not become a mainstream treatment for cancer treatment; however, they also show the possibility that AA can be used in therapies to suppress CSCs.

Targeted Metabolomics Highlights Dramatic Antioxidant Depletion, Increased Oxidative/Nitrosative Stress and Altered Purine and Pyrimidine Concentrations in Serum of Primary Myelofibrosis Patients

To date, little is known concerning the circulating levels of biochemically relevant metabolites (antioxidants, oxidative/nitrosative stress biomarkers, purines, and pyrimidines) in patients with primary myelofibrosis (PMF), a rare form of myeloproliferative tumor causing a dramatic decrease in erythropoiesis and angiogenesis. In this study, using a targeted metabolomic approach, serum samples of 22 PMF patients and of 22 control healthy donors were analyzed to quantify the circulating concentrations of hypoxanthine, xanthine, uric acid (as representative purines), uracil, β-pseudouridine, uridine (as representative pyrimidines), reduced glutathione (GSH), ascorbic acid (as two of the main water-soluble antioxidants), malondialdehyde, nitrite, nitrate (as oxidative/nitrosative stress biomarkers) and creatinine, using well-established HPLC method for their determination. Results showed that PMF patients have dramatic depletions of both ascorbic acid and GSH (37.3- and 3.81-times lower circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001), accompanied by significant increases in malondialdehyde (MDA) and nitrite + nitrate (4.73- and 1.66-times higher circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001). Additionally, PMF patients have remarkable alterations of circulating purines, pyrimidines, and creatinine, suggesting potential mitochondrial dysfunctions causing energy metabolism imbalance and consequent increases in these cell energy-related compounds. Overall, these results, besides evidencing previously unknown serum metabolic alterations in PMF patients, suggest that the determination of serum levels of the aforementioned compounds may be useful to evaluate PMF patients on hospital admission for adjunctive therapies aimed at recovering their correct antioxidant status, as well as to monitor patients' status and potential pharmacological treatments.

Differential effects of ascorbic acid on monocytic cell morphology and protein modification: Shifting from pro-oxidative to antioxidant properties

In this study, we investigated the properties of ascorbic acid (vitamin C), which is a naturally occurring water-soluble vitamin. Our goal is to evaluate its pro-oxidative and/or antioxidant capabilities. To do this, we initially used a confocal laser scanning microscope (CLSM) to visualize the differentiation pattern in U-937 cells under the treatment of variable concentrations of ascorbic acid. Prior to induction, U-937 cells showed a spherical morphology. After treatment, significant morphological changes were observed in the form of prominent pseudopodia and amoeboid structures. Interestingly, pseudopodia incidences increased with an increase in ascorbic acid concentrations. In addition, our analysis of protein modification using anti-malondialdehyde antibodies showed changes in more than one protein. The findings reveal the link between the differentiation of U-937 cells into macrophages and the protein modifications triggered by the production of reactive oxygen species when U-937 cells are exposed to ascorbic acid. Furthermore, the transformation of ascorbic acid from a pro-oxidative to an antioxidant property is also demonstrated.

Role of vitamins A, C, D, E in cancer prevention and therapy: therapeutic potentials and mechanisms of action

Cancer, a leading global cause of mortality, arises from intricate interactions between genetic and environmental factors, fueling uncontrolled cell growth. Amidst existing treatment limitations, vitamins have emerged as promising candidates for cancer prevention and treatment. This review focuses on Vitamins A, C, E, and D because of their protective activity against various types of cancer. They are essential as human metabolic coenzymes. Through a critical exploration of preclinical and clinical studies via PubMed and Google Scholar, the impact of these vitamins on cancer therapy was analyzed, unraveling their complicated mechanisms of action. Interestingly, vitamins impact immune function, antioxidant defense, inflammation, and epigenetic regulation, potentially enhancing outcomes by influencing cell behavior and countering stress and DNA damage. Encouraging clinical trial results have been observed; however, further well-controlled studies are imperative to validate their effectiveness, determine optimal dosages, and formulate comprehensive cancer prevention and treatment strategies. Personalized supplementation strategies, informed by medical expertise, are pivotal for optimal outcomes in both clinical and preclinical contexts. Nevertheless, conclusive evidence regarding the efficacy of vitamins in cancer prevention and treatment is still pending, urging further research and exploration in this compelling area of study.

Combination of Vitamin C and Lenvatinib potentiates antitumor effects in hepatocellular carcinoma cells in vitro

Lenvatinib has become a first-line drug in the treatment of advanced hepatocellular carcinoma (HCC). Investigating its use in combination with other agents is of great significance to improve the sensitivity and durable response of Lenvatinib in advanced HCC patients. Vitamin C (L-ascorbic acid, ascorbate, VC) is an important natural antioxidant, which has been reported to show suppressive effects in cancer treatment. Here, we investigated the effect of the combination of VC and Lenvatinib in HCC cells in vitro. We found that treatment of VC alone significantly inhibited the proliferation, migration and invasion in HCC cells. Additionally, VC was strongly synergistic with Lenvatinib in inhibition of the proliferative, migratory and invasive capacities of HCC cells in vitro. In conclusion, our results demonstrate that the combination of VC and Lenvatinib has synergistic antitumor activities against HCC cells, providing a promising therapeutic strategy to improve the prognosis of HCC patients.

Biopolymer Nanovehicles for Oral Delivery of Natural Anticancer Agents

Cancer is the second leading cause of death throughout the world. Nature‐inspired anticancer agents (NAAs) that are a gift of nature to humanity have been extensively utilized in the alleviation/prevention of the disease due to their numerous pharmacological activities. While the oral route is an ideal and common way of drug administration, the application of NAAs through the oral pathway has been extremely limited owing to their inherent features, e.g., poor solubility, gastrointestinal (GI) instability, and low bioavailability. With the development of nano‐driven encapsulation strategies, polymeric vehicles, especially those with natural origins, have demonstrated a potent platform, which can professionally shield versatile NAAs against GI barricades and safely deliver them to the site of action. In this review, the predicament of orally delivering NAAs and the encapsulation strategy solutions based on biopolymer matrices are summarized. Proof‐of‐concept in vitro/in vivo results are also discussed for oral delivery of these agents by various biopolymer vehicles, which can be found so far from the literature. Last but not the least, the challenges and new opportunities in the field are highlighted.

Effect of vitamins C and E on cancer survival; a systematic review

PURPOSE

Association between vitamins C (VC)/ E (VE) and cancer survival is inconsistent. This systematic review is aimed to summarize trials for effects of VC/VE on cancer survival.

METHODS

Relevant English trials were retrieved from PubMed, Cochrane Library, Embase, Web of Science, Scopus databases, and Clinicaltrials.gov through 21/June/2022. Inclusion criteria were all trials which assessed sole/combinations intake of VC/VE on survival rate, mortality, or remission of any cancer. Exclusion criteria were observational and animal studies.

RESULTS

We reached 30 trials conducted on 38,936 patients with various cancers. Due to severe methodological heterogeneity, meta-analysis was impossible. High dose VC + chemotherapy or radiation was safe with an overall survival (OS) 182 days - 21.5 months. Sole oral or intravenous high dose VC was safe with non-significant change in OS (2.9-8.2 months). VE plus chemotherapy was safe, resulted in stabling diseases for 5 years in 70- 86.7% of patients and OS 109 months. It was found 60% and 16% non-significant reductions in adjusted hazard ratio (HR) deaths or recurrence by 200 mg/d tocotrienol + tamoxifen in breast cancer, respectively. Sole intake of 200-3200 mg/d tocotrienol before resectable pancreatic cancer was safe and significantly increased cancer cells' apoptosis. Combination VC and VE was non-significantly reduced 7% in rate of neoplastic gastric polyp.

CONCLUSION

Although our study is supported improvement of survival and progression rates of cancers by VC/VE, more high quality trials with large sample sizes are required to confirm.

PROSPERO REGISTRATION NUMBER

CRD42020152795.

Glioblastoma Invasiveness and Collagen Secretion Are Enhanced by Vitamin C

Aims: Glioblastoma (GB) is one of the most aggressive brain tumors. These tumors modify their metabolism, increasing the expression of glucose transporters, GLUTs, which incorporate glucose and the oxidized form of vitamin C, dehydroascorbic acid (DHA). We hypothesized that GB cells preferentially take up DHA, which is intracellularly reduced and compartmentalized into the endoplasmic reticulum (ER), promoting collagen biosynthesis and an aggressive phenotype. Results: Our results showed that GB cells take up DHA using GLUT1, while GLUT3 and sodium-dependent vitamin C transporter 2 (SVCT2) are preferably intracellular. Using a baculoviral system and reticulum-enriched extracts, we determined that SVCT2 is mainly located in the ER and corresponds to a short isoform. Ascorbic acid (AA) was compartmentalized, stimulating collagen IV secretion and increasing in vitro and in situ cell migration. Finally, orthotopic xenografts induced in immunocompetent guinea pigs showed that vitamin C deficiency retained collagen, reduced blood vessel invasion, and affected glomeruloid vasculature formation, all pathological conditions associated with malignancy. Innovation and Conclusion: We propose a functional role for vitamin C in GB development and progression. Vitamin C is incorporated into the ER of GB cells, where it favors the synthesis of collagen, thus impacting tumor development. Collagen secreted by tumor cells favors the formation of the glomeruloid vasculature and enhances perivascular invasion. Antioxid. Redox Signal. 37, 538-559.

Antioxidant Properties and Aldehyde Reactivity of PD-L1 Targeted Aryl-Pyrazolone Anticancer Agents

Small molecules targeting the PD-1/PD-L1 checkpoint are actively searched to complement the anticancer arsenal. Different molecular scaffolds have been reported, including phenyl-pyrazolone derivatives which potently inhibit binding of PD-L1 to PD-1. These molecules are structurally close to antioxidant drug edaravone (EDA) used to treat amyotrophic lateral sclerosis. For this reason, we investigated the capacity of five PD-L1-binding phenyl-pyrazolone compounds (1–5) to scavenge the formation of oxygen free radicals using electron spin resonance spectroscopy with DPPH/DMPO probes. In addition, the reactivity of the compounds toward the oxidized base 5-formyluracil (5fU) was assessed using chromatography coupled to mass spectrometry and photodiode array detectors. The data revealed that the phenyl-pyrazolone derivatives display antioxidant properties and exhibit a variable reactivity toward 5fU. Compound 2 with a N-dichlorophenyl-pyrazolone moiety cumulates the three properties, being a potent PD-L1 binder, a robust antioxidant and an aldehyde-reactive compound. On the opposite, the adamantane derivative 5 is a potent PD-L1 binding with a reduced antioxidant potential and no aldehyde reactivity. The nature of the substituent on the phenyl-pyrazolone core modulates the antioxidant capacity and reactivity toward aromatic aldehydes. The molecular signature of the compound can be adapted at will, to confer additional properties to these PD-L1 binders.

Improvement of the anticancer efficacy of PD-1/PD-L1 blockade via combination therapy and PD-L1 regulation

Immune checkpoint molecules are promising anticancer targets, among which therapeutic antibodies targeting the PD-1/PD-L1 pathway have been widely applied to cancer treatment in clinical practice and have great potential. However, this treatment is greatly limited by its low response rates in certain cancers, lack of known biomarkers, immune-related toxicity, innate and acquired drug resistance, etc. Overcoming these limitations would significantly expand the anticancer applications of PD-1/PD-L1 blockade and improve the response rate and survival time of cancer patients. In the present review, we first illustrate the biological mechanisms of the PD-1/PD-L1 immune checkpoints and their role in the healthy immune system as well as in the tumor microenvironment (TME). The PD-1/PD-L1 pathway inhibits the anticancer effect of T cells in the TME, which in turn regulates the expression levels of PD-1 and PD-L1 through multiple mechanisms. Several strategies have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including combination therapy with other standard treatments, such as chemotherapy, radiotherapy, targeted therapy, anti-angiogenic therapy, other immunotherapies and even diet control. Downregulation of PD-L1 expression in the TME via pharmacological or gene regulation methods improves the efficacy of anti-PD-1/PD-L1 treatment. Surprisingly, recent preclinical studies have shown that upregulation of PD-L1 in the TME also improves the response and efficacy of immune checkpoint blockade. Immunotherapy is a promising anticancer strategy that provides novel insight into clinical applications. This review aims to guide the development of more effective and less toxic anti-PD-1/PD-L1 immunotherapies.

Vitamin C Differentially Impacts the Serum Proteome Profile in Female and Male Mice

A suboptimal blood vitamin C (ascorbate) level increases the risk of several chronic diseases. However, the detection of hypovitaminosis C is not a simple task, as ascorbate is unstable in blood samples. In this study, we examined the serum proteome of mice lacking the gulonolactone oxidase (Gulo) required for the ascorbate biosynthesis. Gulo^-/- mice were supplemented with different concentrations of ascorbate in drinking water, and serum was collected to identify proteins correlating with serum ascorbate levels using an unbiased label-free liquid chromatography-tandem mass spectrometry global quantitative proteomic approach. Parallel reaction monitoring was performed to validate the correlations. We uncovered that the serum proteome profiles differ significantly between male and female mice. Also, unlike Gulo^-/- males, a four-week ascorbate treatment did not entirely re-establish the serum proteome profile of ascorbate-deficient Gulo^-/- females to the optimal profile exhibited by Gulo^-/- females that never experienced an ascorbate deficiency. Finally, the serum proteins involved in retinoid metabolism, cholesterol, and lipid transport were similarly affected by ascorbate levels in males and females. In contrast, the proteins regulating serum peptidases and the protein of the acute phase response were different between males and females. These proteins are potential biomarkers correlating with blood ascorbate levels and require further study in standard clinical settings. The complete proteomics data set generated in this study has been deposited to the public repository ProteomeXchange with the data set identifier: PXD027019.

Molecular and Metabolic Reprogramming: Pulling the Strings Toward Tumor Metastasis

Metastasis is a major hurdle to the efficient treatment of cancer, accounting for the great majority of cancer-related deaths. Although several studies have disclosed the detailed mechanisms underlying primary tumor formation, the emergence of metastatic disease remains poorly understood. This multistep process encompasses the dissemination of cancer cells to distant organs, followed by their adaptation to foreign microenvironments and establishment in secondary tumors. During the last decades, it was discovered that these events may be favored by particular metabolic patterns, which are dependent on reprogrammed signaling pathways in cancer cells while they acquire metastatic traits. In this review, we present current knowledge of molecular mechanisms that coordinate the crosstalk between metastatic signaling and cellular metabolism. The recent findings involving the contribution of crucial metabolic pathways involved in the bioenergetics and biosynthesis control in metastatic cells are summarized. Finally, we highlight new promising metabolism-based therapeutic strategies as a putative way of impairing metastasis.

Nanotechnology in Oral Cancer Prevention and Therapeutics: A Literature Review

The concept of nanotechnology revolves around the delivery of nano particle incorporated drugs which are originally engineered technology. Nanoparticles are used for targeted delivery and controlled release of a curative agents. Nanotechnology is gaining importance and is likely to be routine element of regular dental clinics. Nanomaterials are being incorporated in toothpastes, mouth rinses for improved efficiencies. It has found its use in restorative dental materials, anti-cariogenic enamel surface polishing agents, implant materials, etc. Few nanoparticles possess antimicrobial propertiesand intercepts bacterial activity. Nano dentistry is cost-effectiveness and timesaving compared to other techniques. Nano particles have also been beneficial to annihilate drug resistance, prevention of metastasis or lesion recurrence by earmarking malignant stem cells. Remarkable achievements were made in using nanoparticles for detecting and treating multiple variety of malignancies including colon cancer, prostate cancer, lung cancer, breast cancer, head and neck cancer, etc. This review was made to highlight the various clinical applications of nanotechnology in the diagnosis and curative care for oral cancer.