Antitumor effect of pharmacologic ascorbate in the B16 murine melanoma model

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.

High-Dose Ascorbate in Combination with Anti-PD1 Checkpoint Inhibition as Treatment Option for Malignant Melanoma

Ascorbate acts as a prooxidant when administered parenterally at high supraphysiological doses, which results in the generation of hydrogen peroxide in dependence on oxygen. Most cancer cells are susceptible to the emerging reactive oxygen species (ROS). Accordingly, we evaluated high-dose ascorbate for the treatment of the B16F10 melanoma model. To investigate the effects of ascorbate on the B16F10 cell line in vitro, viability, cellular impedance, and ROS production were analyzed. In vivo, C57BL/6NCrl mice were subcutaneously injected into the right flank with B16F10 cells and tumor-bearing mice were treated intraperitoneally with ascorbate (3 g/kg bodyweight), immunotherapy (anti-programmed cell death protein 1 (PD1) antibody J43; 2 mg/kg bodyweight), or both treatments combined. The efficacy and toxicity were analyzed by measuring the respective tumor sizes and mouse weights accompanied by histological analysis of the protein levels of proliferating cell nuclear antigen (Pcna), glucose transporter 1 (Glut-1), and CD3. Treatment of B16F10 melanoma-carrying mice with high-dose ascorbate yielded plasma levels in the pharmacologically effective range, and ascorbate showed efficacy as a monotherapy and when combined with PD1 inhibition. Our data suggest the applicability of ascorbate as an additional therapeutic agent that can be safely combined with immunotherapy and has the potential to potentiate anti-PD1-based immune checkpoint blockades.

Antineoplastic Effects of Ankaferd Hemostat

Objectıve. Ankaferd hemostat (ABS; Ankaferd Blood Stopper®) contains standardized plant extracts comprising Alpinia officinarum, Glycyrrhiza glabra, Thymus vulgaris, Urtica dioica, and Vitis vinifera. ABS especially was recognized for its hemostatic effect; however, antineoplastic role of ABS was identified during the last decade. The aim of this paper is to review the molecular basis and associated clinical implications of the ABS as a topical antineoplastic agent. Materials and Methods. Up to June 2022, literature searches were performed using the internet search engines Medline, Google Scholar, and Embase: Ankaferd. PRISMA flow diagram described the Ankaferd search. Results. ABS have important effects in several cellular processes, like control of the cell cycle, apoptosis, angiogenesis, signal transduction, inflammation, immunologic, and metabolic mechanisms. The molecular basis of antineoplastic roles of ABS depends on its proteomics, metabolomics, and transcriptomics features. ABS has antineoplastic effects on solid tumors like colon, bladder, breast, and osteosarcoma cancer cells. Also, ABS effects renal tubular apoptosis and has antitumoral roles on malign melanoma cells. ABS inhibits hematological tumors like myeloma and lymphoid cells. ABS induces apoptosis in retinal cells and has inhibitory effects on mesenchymal stem cells. It has an antiproliferative role on gastrointestinal tumors like hepatocellular carcinoma cells. Moreover, ABS has a treatment supportive role in cancer since it can prevent oxidative DNA damage and decrease the intestinal damage in necrotizing enterocolitis. Furthermore, it has chemopreventive and hepatoprotective features and can be used for prophylaxis and treatment of oral mucositis. Conclusion. ABS alters cell metabolism and cell cycle. ABS has antineoplastic role on cancer cells. The expanding context of ABS compromises anti-infective, antineoplastic, and wound healing features. ABS may also be used for the palliative, adjuvant, neoadjuvant, or supportive use by interventional radiology procedures for the treatment of solid tumors. Future controlled studies are necessary to clarify the pleiotropic role of ABS like antineoplastic, antithrombotic, anti-inflammatory, anti-infective, antifungal, and antioxidative effects.

Therapeutic Efficacy of Pharmacological Ascorbate on Braf Inhibitor Resistant Melanoma Cells In Vitro and In Vivo

High-dose ascorbate paradoxically acts as a pro-oxidant causing the formation of hydrogen peroxide in an oxygen dependent manner. Tumor cells (in particular melanoma cells) show an increased vulnerability to ascorbate induced reactive oxygen species (ROS). Therefore, high-dose ascorbate is a promising pharmacological approach to treating refractory melanomas, e.g., with secondary resistance to targeted BRAF inhibitor therapy. BRAF mutated melanoma cells were treated with ascorbate alone or in combination with the BRAF inhibitor vemurafenib. Viability, cell cycle, ROS production, and the protein levels of phospho-ERK1/2, GLUT-1 and HIF-1α were analyzed. To investigate the treatment in vivo, C57BL/6NCrl mice were subcutaneously injected with D4M.3A (Braf^V600E) melanoma cells and treated with intraperitoneal injections of ascorbate with or without vemurafenib. BRAF mutated melanoma cell lines either sensitive or resistant to vemurafenib were susceptible to the induction of cell death by pharmacological ascorbate. Treatment of Braf^V600E melanoma bearing mice with ascorbate resulted in plasma levels in the pharmacologically active range and significantly improved the therapeutic effect of vemurafenib. We conclude that intravenous high-dose ascorbate will be beneficial for melanoma patients by interfering with the tumor’s energy metabolism and can be safely combined with standard melanoma therapies such as BRAF inhibitors without pharmacological interference.

Vitamin C, From Supplement to Treatment: A Re-Emerging Adjunct for Cancer Immunotherapy?

Vitamin C (VitC), in addition to its role as a general antioxidant, has long been considered to possess direct anti-cancer activity at high doses. VitC acts through oxidant and epigenetic mechanisms, which at high doses can exert direct killing of tumor cells in vitro and delay tumor growth in vivo. Recently, it has also been shown that pharmacologic-dose VitC can contribute to control of tumors by modulating the immune system, and studies have been done interrogating the role of physiologic-dose VitC on novel adoptive cellular therapies (ACTs). In this review, we discuss the effects of VitC on anti-tumor immune cells, as well as the mechanisms underlying those effects. We address important unanswered questions concerning both VitC and ACTs, and outline challenges and opportunities facing the use of VitC in the clinical setting as an adjunct to immune-based anti-cancer therapies.

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

Mounting evidence indicates that vitamin C has the potential to be a potent anti-cancer agent when administered intravenously and in high doses (high-dose IVC). Early phase clinical trials have confirmed safety and indicated efficacy of IVC in eradicating tumour cells of various cancer types. In recent years, the multi-targeting effects of vitamin C were unravelled, demonstrating a role as cancer-specific, pro-oxidative cytotoxic agent, anti-cancer epigenetic regulator and immune modulator, reversing epithelial-to-mesenchymal transition, inhibiting hypoxia and oncogenic kinase signalling and boosting immune response. Moreover, high-dose IVC is powerful as an adjuvant treatment for cancer, acting synergistically with many standard (chemo-) therapies, as well as a method for mitigating the toxic side-effects of chemotherapy. Despite the rationale and ample evidence, strong clinical data and phase III studies are lacking. Therefore, there is a need for more extensive awareness of the use of this highly promising, non-toxic cancer treatment in the clinical setting. In this review, we provide an elaborate overview of pre-clinical and clinical studies using high-dose IVC as anti-cancer agent, as well as a detailed evaluation of the main known molecular mechanisms involved. A special focus is put on global molecular profiling studies in this respect. In addition, an outlook on future implications of high-dose vitamin C in cancer treatment is presented and recommendations for further research are discussed.

High-dose vitamin C enhances cancer immunotherapy

Vitamin C (VitC) is known to directly impair cancer cell growth in preclinical models, but there is little clinical evidence on its antitumoral efficacy. In addition, whether and how VitC modulates anticancer immune responses is mostly unknown. Here, we show that a fully competent immune system is required to maximize the antiproliferative effect of VitC in breast, colorectal, melanoma, and pancreatic murine tumors. High-dose VitC modulates infiltration of the tumor microenvironment by cells of the immune system and delays cancer growth in a T cell-dependent manner. VitC not only enhances the cytotoxic activity of adoptively transferred CD8 T cells but also cooperates with immune checkpoint therapy (ICT) in several cancer types. Combination of VitC and ICT can be curative in models of mismatch repair-deficient tumors with high mutational burden. This work provides a rationale for clinical trials combining ICT with high doses of VitC.

Tropinone-Derived Alkaloids as Potent Anticancer Agents: Synthesis, Tyrosinase Inhibition, Mechanism of Action, DFT Calculation, and Molecular Docking Studies

A new series of hybrid compounds with tropinone and thiazole rings in the structure was designed and synthesized as potential anticancer agents. They were tested against human multiple myeloma (RPMI 8226), lung carcinoma (A549), breast adenocarcinoma (MDA-MB-231), and mouse skin melanoma (B16-F10) cell lines. Toxicity was tested on human normal skin fibroblasts (HSF) and normal colon fibroblasts (CCD-18Co). The growth inhibition mechanism of the most active derivative was analyzed through investigation of its effect on the distribution of cell cycle phases and ability to induce apoptosis and necrosis in RPMI 8226 and A549 cancer cells. The tyrosinase inhibitory potential was assessed, followed by molecular docking studies. Compounds 3a–3h show high anticancer activity against MDA-MB-231 and B16-F10 cell lines with IC₅₀ values of 1.51–3.03 µM. Moreover, the cytotoxic activity of the investigated compounds against HSF and CCD-18Co cells was 8–70 times lower than against the cancer cells or no toxicity was shown in our tests, with derivative 3a being particularly successful. The mechanism of action of compound 3a in RPMI 8226 cell was shown to be through induction of cell death through apoptosis. The derivatives show ability to inhibit the tyrosinase activity with a mixed mechanism of inhibition. The final molecular docking results showed for IC₅₀ distinct correlation with experiment.

The Xc- inhibitor sulfasalazine improves the anti-cancer effect of pharmacological vitamin C in prostate cancer cells via a glutathione-dependent mechanism

PURPOSE

Traditional treatment regimens for advanced prostate cancer, especially castration-resistant prostate cancer, result in low survival times with severe side effects. Therefore, new treatment options are required. Vitamin C (VC) has been identified as a promising anti-cancer agent of which the effects depend on the accumulation of H₂O₂ that is produced through autoxidation. Sulfasalazine (SAS), a cystine transporter (X_c^-) inhibitor, is known to suppress cellular glutathione (GSH) biosynthesis. Here, we hypothesized that targeting the X_c^- transporter via SAS may improve the anti-cancer activity of VC through regulating GSH biosynthesis, which in turn may result in the accumulation of reactive oxygen species (ROS).

METHODS

The anti-cancer effect of VC and/or SAS on prostate cancer cells was assessed using WST-8, colony formation and annexin V-FITC/PI FACS assays. Changes in cellular ROS and GSH levels were determined to verify our hypothesis. Finally, BALB/c nude mice bearing prostate cancer xenografts were used to assess the anti-cancer effects of single or combined VC and SAS therapies.

RESULTS

We found that SAS could potentiate the short- and long-term cytotoxicity of VC in prostate cancer cells. We also found that the synergistic effect of SAS and VC led to significant cellular GSH depletion, resulting in increased ROS accumulation. This synergistic effect could be reversed by the antioxidant N-acetyl-L-cysteine (NAC). The synergistic effect of SAS and VC was also noted in prostate cancer xenografts and correlated with immunohistochemistry results.

CONCLUSIONS

Our results strongly indicate that SAS, a relatively non-toxic drug that targets cystine transporters, in combination with VC may be superior to their single applications in the treatment of prostate cancer.

Ascorbic Acid in Cancer Treatment: Let the Phoenix Fly

Vitamin C (ascorbic acid, ascorbate), despite controversy, has re-emerged as a promising anti-cancer agent. Recent knowledge of intravenous ascorbate pharmacokinetics and discovery of unexpected mechanisms of ascorbate action have spawned many investigations. Two mechanisms of anti-cancer activity with ascorbate have gained prominence: hydrogen peroxide-induced oxidative stress and DNA demethylation mediated by ten-eleven translocation enzyme activation. Here, we highlight salient aspects of the evolution of ascorbate in cancer treatment, provide insights into the pharmacokinetics of ascorbate, describe mechanisms of its anti-cancer activity in relation to the pharmacokinetics, outline promising preclinical and clinical evidence, and recommend future directions.

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.

Ascorbic Acid Chemosensitizes Colorectal Cancer Cells and Synergistically Inhibits Tumor Growth

Colorectal cancer (CRC) is continuously classified as one of the most incidental and mortal types of cancer worldwide. The positive outcomes of the conventional chemotherapy are frequently associated with high toxicity, which often leads to the suspension of the treatment. Growing evidences consider the use of pharmacological concentrations of ascorbic acid (AA), better known as vitamin C, in the treatment of cancer. The use of AA in a clinical context is essentially related to the adoption of new therapeutic strategies based on combination regimens, where AA plays a chemosensitizing role. The reduced sensitivity of some tumors to chemotherapy and the highly associated adverse effects continue to be some of the major obstacles in the effective treatment of CRC. So, this paper aimed to study the potential of a new therapeutic approach against this neoplasia with diminished side effects for the patient. This approach was based on the study of the combination of high concentrations of AA with reduced concentrations of drugs conventionally used in CRC patients and eligible for first and second line chemotherapeutic regimens, namely 5-fluorouracilo (5-FU), oxaliplatin (Oxa) or irinotecan (Iri). The evaluation of the potential synergy between the compounds was first assessed in vitro in three CRC cell lines with different genetic background and later in vivo using one xenograft animal model of CRC. AA and 5-FU act synergistically in vitro just for longer incubation times, however, in vivo showed no benefit compared to 5-FU alone. In contrast to the lack of synergy seen in in vitro studies with the combination of AA with irinotecan, the animal model revealed the therapeutic potential of this combination. AA also potentiated the effect of Oxa, since a synergistic effect was demonstrated, in almost all conditions and in the three cell lines. Moreover, this combined therapy (CT) caused a stagnation of the tumor growth rate, being the most promising tested combination. Pharmacological concentrations of AA increased the efficacy of Iri and Oxa against CRC, with promising results in cell lines with more aggressive phenotypes, namely, tumors with mutant or null P53 expression and tumors resistant to chemotherapy.

Pharmacologic ascorbate (P-AscH-) suppresses hypoxia-inducible Factor-1α (HIF-1α) in pancreatic adenocarcinoma

HIF-1α is a transcriptional regulator that functions in the adaptation of cells to hypoxic conditions; it strongly impacts the prognosis of patients with cancer. High-dose, intravenous, pharmacological ascorbate (P-AscH^-), induces cytotoxicity and oxidative stress selectively in cancer cells by acting as a pro-drug for the delivery of hydrogen peroxide (H₂O₂); early clinical data suggest improved survival and inhibition of metastasis in patients being actively treated with P-AscH^-. Previous studies have demonstrated that activation of HIF-1α is necessary for P-AscH^- sensitivity. We hypothesized that pancreatic cancer (PDAC) progression and metastasis could be be targeted by P-AscH^- via H₂O₂-mediated inhibition of HIF-1α stabilization. Our study demonstrates an oxygen- and prolyl hydroxylase-independent regulation of HIF-1α by P-AscH^-. Additionally, P-AscH^- decreased VEGF secretion in a dose-dependent manner that was reversible with catalase, consistent with an H₂O₂-mediated mechanism. Pharmacological and genetic manipulations of HIF-1α did not alter P-AscH^--induced cytotoxicity. In vivo, P-AscH^- inhibited tumor growth and VEGF expression. We conclude that P-AscH^- suppresses the levels of HIF-1α protein in hypoxic conditions through a post-translational mechanism. These findings suggest potential new therapies specifically designed to inhibit the mechanisms that drive metastases as a part of PDAC treatment.

Mechanisms and prevention of UV-induced melanoma

Melanoma is the deadliest form of skin cancer and its incidence is rising, creating a costly and significant clinical problem. Exposure to ultraviolet (UV) radiation, namely UVA (315-400 nm) and UVB (280-315 nm), is a major risk factor for melanoma development. Cumulative UV radiation exposure from sunlight or tanning beds contributes to UV-induced DNA damage, oxidative stress, and inflammation in the skin. A number of factors, including hair color, skin type, genetic background, location, and history of tanning, determine the skin's response to UV radiation. In melanocytes, dysregulation of this UV radiation response can lead to melanoma. Given the complex origins of melanoma, it is difficult to develop curative therapies and universally effective preventative strategies. Here, we describe and discuss the mechanisms of UV-induced skin damage responsible for inducing melanomagenesis, and explore options for therapeutic and preventative interventions.

An integrated approach identifies new oncotargets in melanoma

Melanoma is an aggressive skin cancer; an early detection of the primary tumor may improve its prognosis. Despite many genes have been shown to be involved in melanoma, the full framework of melanoma transformation has not been completely explored. The characterization of pathways involved in tumor restraint in in vitro models may help to identify oncotarget genes. We therefore aimed to probe novel oncotargets through an integrated approach involving proteomic, gene expression and bioinformatic analysis We investigated molecular modulations in melanoma cells treated with ascorbic acid, which is known to inhibit cancer growth at high concentrations. For this purpose a proteomic approach was applied. A deeper insight into ascorbic acid anticancer activity was achieved; the discovery of deregulated processes suggested further biomarkers. In addition, we evaluated the expression of identified genes as well as the migration ability in several melanoma cell lines. Data obtained by a multidisciplinary approach demonstrated the involvement of Enolase 1 (ENO1), Parkinsonism-associated deglycase (PARK7), Prostaglansin E synthase 3 (PTGES3), Nucleophosmin (NPM1), Stathmin 1 (STMN1) genes in cell transformation and identified Single stranded DNA binding protein 1 (SSBP1) as a possible onco-suppressor in melanoma cancer.

RIG-I Resists Hypoxia-Induced Immunosuppression and Dedifferentiation

A hypoxic tumor microenvironment is linked to poor prognosis. It promotes tumor cell dedifferentiation and metastasis and desensitizes tumor cells to type-I IFN, chemotherapy, and irradiation. The cytoplasmic immunoreceptor retinoic acid-inducible gene-I (RIG-I) is ubiquitously expressed in tumor cells and upon activation by 5'-triphosphate RNA (3pRNA) drives the induction of type I IFN and immunogenic cell death. Here, we analyzed the impact of hypoxia on the expression of RIG-I in various human and murine tumor and nonmalignant cell types and further investigated its function in hypoxic murine melanoma. 3pRNA-inducible RIG-I-expression was reduced in hypoxic melanoma cells compared with normoxic controls, a phenomenon that depended on the hypoxia-associated transcription factor HIF1α. Still, RIG-I functionality was conserved in hypoxic melanoma cells, whereas responsiveness to recombinant type-I IFN was abolished, due to hypoxia-induced loss of type I IFN receptor expression. Likewise, RIG-I activation in hypoxic melanoma cells, but not exposure to recombinant IFNα, provoked melanocyte antigen-specific CD8⁺ T-cell and NK-cell attack. Scavenging of hypoxia-induced reactive oxygen species by vitamin C restored the inducible expression of RIG-I under hypoxia in vitro, boosted in vitro anti-melanoma NK- and CD8⁺ T-cell attack, and augmented 3pRNA antitumor efficacy in vivo These results demonstrate that RIG-I remains operational under hypoxia and that RIG-I function is largely insensitive to lower cell surface expression of the IFNα receptor. RIG-I function could be fortified under hypoxia by the combined use of 3pRNA with antioxidants. Cancer Immunol Res; 5(6); 455-67. ©2017 AACR.

In Vitro and In Vivo Antimetastatic Effect of Glutathione Disulfide Liposomes

Cancer metastasis is the major cause of cancer mortality. Despite extensive research efforts, effective treatment for cancer metastasis is still lacking. Cancer metastasis involves 4 essential steps: cell detachment, migration, invasion, and adhesion. Detachment is the first and required step for metastasis. Glutathione disulfide (GSSG) is derived from the oxidation of glutathione (GSH), which is present in biological systems in millimolar concentration. Although GSSG is commercially available, the impact of GSSG on cell functions/dysfunctions has not been fully explored due to the fact that GSSG is not cell membrane permeable and a lack of method to specifically increase GSSG in cells. We have developed GSSG liposomes that effectively deliver GSSG to cells. Unexpectedly, cells treated with GSSG liposomes were resistant to detachment by trypsinization. This observation led to the investigation of the antimetastatic effect of GSSG liposomes. Our data demonstrate that GSSG liposomes at 1 mg/mL completely blocked cell detachment and migration, and significantly inhibited cancer cell invasion. Aqueous GSSG showed no such effect, confirming that the effects on cell detachment, migration, and invasion were caused by the intracellular delivery of GSSG. An in vivo experiment with a murine melanoma experimental metastasis model showed that GSSG liposomes prevented melanoma lung metastasis. The unique antimetastatic mechanism through the effects on detachment and migration, and effective in vitro and in vivo metastasis inhibition, warrants further investigation of the GSSG liposomes as a potential treatment for cancer metastasis.

Growth inhibitory activity of Ankaferd hemostat on primary melanoma cells and cell lines

Objective:

Ankaferd hemostat is the first topical hemostatic agent about the red blood cell–fibrinogen relations tested in the clinical trials. Ankaferd hemostat consists of standardized plant extracts including Alpinia officinarum, Glycyrrhiza glabra, Thymus vulgaris, Urtica dioica, and Vitis vinifera. The aim of this study was to determine the effect of Ankaferd hemostat on viability of melanoma cell lines.

Methods:

Dissimilar melanoma cell lines and primary cells were used in this study. These cells were treated with different concentrations of Ankaferd hemostat to assess the impact of different dosages of the drug. All cells treated with different concentrations were incubated for different time intervals. After the data had been obtained, one-tailed T-test was used to determine whether the Ankaferd hemostat would have any significant inhibitory impact on cell growth.

Results:

We demonstrated in this study that cells treated with Ankaferd hemostat showed a significant decrease in cell viability compared to control groups. The cells showed different resistances against Ankaferd hemostat which depended on the dosage applied and the time treated cells had been incubated. We also demonstrated an inverse relationship between the concentration of the drug and the incubation time on one hand and the viability of the cells on the other hand, that is, increasing the concentration of the drug and the incubation time had a negative impact on cell viability.

Conclusion:

The findings in our study contribute to our knowledge about the anticancer impact of Ankaferd hemostat on different melanoma cells.

TET2 Negatively Regulates Nestin Expression in Human Melanoma

Although melanoma is an aggressive cancer, the understanding of the virulence-conferring pathways involved remains incomplete. We have demonstrated that loss of ten-eleven translocation methylcytosine dioxygenase (TET2)-mediated 5-hydroxymethylcytosine (5-hmC) is an epigenetic driver of melanoma growth and a biomarker of clinical virulence. We also have determined that the intermediate filament protein nestin correlates with tumorigenic and invasive melanoma growth. Here we examine the relationships between these two biomarkers. Immunohistochemistry staining of nestin and 5-hmC in 53 clinically annotated primary and metastatic patient melanomas revealed a significant negative correlation. Restoration of 5-hmC, as assessed in a human melanoma cell line by introducing full-length TET2 and TET2-mutated constructs, decreased nestin gene and protein expression in vitro. Genome-wide mapping using hydroxymethylated DNA immunoprecipitation sequencing disclosed significantly less 5-hmC binding in the 3' untranslated region of the nestin gene in melanoma compared to nevi, and 5-hmC binding in this region was significantly increased after TET2 overexpression in human melanoma cells in vitro. Our findings provide evidence suggesting that nestin regulation is negatively controlled epigenetically by TET2 via 5-hmC binding at the 3' untranslated region of the nestin gene, providing one potential pathway for understanding melanoma growth characteristics. Studies are now indicated to further define the interplay between 5-hmC, nestin expression, and melanoma virulence.