Vitamin D-VDR Signaling Inhibits Wnt/β-Catenin-Mediated Melanoma Progression and Promotes Antitumor Immunity

Exosomal miR-122 promotes adipogenesis and aggravates obesity through the VDR/SREBF1 axis

OBJECTIVE

This study examined the effects of miR-122-enriched exosomes on the expression of vitamin D3 receptor (VDR) and sterol regulatory element-binding transcription factor 1 (SREBF1) and their roles during adipogenesis.

METHODS

The roles of miR-122, SREBF1, and VDR were investigated during adipogenesis. The relationships between VDR and miR-122 or SREBF1 were assessed by dual-luciferase reporter and chromatin immunoprecipitation assays. The potential role of miR-122/VDR/SREBF1 was evaluated in high-fat diet-induced obese male mice.

RESULTS

High levels of miR-122 were found only in adipose tissue-derived exosomes (Exo-AT) and Exo-AT-treated cells. Overexpression of miR-122 promoted adipogenesis, and inhibition of miR-122 prevented adipogenesis by regulating VDR, SREBF1, peroxisome proliferator-activated receptor gamma, lipoprotein lipase, and adiponectin. Knockdown of Srebf1 or overexpression of VDR could inhibit adipogenesis. However, exosomal miR-122 could reverse their inhibitory effects. The dual-luciferase reporter assay and chromatin immunoprecipitation assays confirmed that VDR was a direct target of miR-122. It could bind to the BS1 region of the SREBF1 promoter and inhibit SREBF1 expression. Moreover, miR-122 inhibition could alleviate obesity in high-fat diet-induced obese male mice, possibly through upregulating the VDR/SREBF1 axis.

CONCLUSION

MiR-122-enriched Exo-AT promoted adipogenesis by regulating the VDR/SREBF1 axis.

Vitamin D Enhances Anticancer Properties of Cediranib, a VEGFR Inhibitor, by Modulation of VEGFR2 Expression in Melanoma Cells

Regardless of the recent groundbreaking introduction of personalized therapy, melanoma continues to be one of the most lethal skin malignancies. Still, a substantial proportion of patients either fail to respond to the therapy or will relapse over time, representing a challenging clinical problem. Recently, we have shown that vitamin D enhances the effectiveness of classical chemotherapeutics in the human malignant melanoma A375 cell line. In search for new combination strategies and adjuvant settings to improve melanoma patient outcomes in the current study, the effects of cediranib (AZD2171), an oral tyrosine kinase inhibitor of VEGFR1-3, PDGFR, and c-KIT, used in combination either with 1,25(OH)₂D₃ or with low-calcemic analog calcipotriol were tested on four human malignant melanoma cell lines (A375, MNT-1, RPMI-7951, and SK-MEL-28). Melanoma cells were pretreated with vitamin D and subsequently exposed to cediranib. We observed a marked decrease in melanoma cell proliferation (A375 and SK-MEL-28), G2/M cell cycle arrest, and a significant decrease in melanoma cell mobility in experimental conditions used (A375). Surprisingly, concurrently with a very desirable decrease in melanoma cell proliferation and mobility, we noticed the upregulation of VEGFR2 at both protein and mRNA levels. No effect of vitamin D was observed in MNT-1 and RPMI-7951 melanoma cells. It seems that vitamin D derivatives enhance cediranib efficacy by modulation of VEGFR2 expression in melanoma cells expressing VEGFR2. In conclusion, our experiments demonstrated that vitamin D derivatives hold promise as novel adjuvant candidates to conquer melanoma, especially in patients suffering from vitamin D deficiency. However, further extensive research is indispensable to reliably assess their potential benefits for melanoma patients.

Conjugate of ibrutinib with a TLR7 agonist suppresses melanoma progression and enhances antitumor immunity

The use of large molecules for immunotherapy has led to exciting developments in cancer treatment, such as the development of PD-1/PD-L1 antibodies. However, small molecule targeted therapies still lack effective immune-functional classes. Ideal anticancer drugs should simultaneously generate immune memory when killing cancer cells to prevent tumor relapse and metastasis. To this end, we carried out a rationally designed strategy to develop novel classes of small molecule compounds with bifunctional targeting and immunostimulatory abilities by conjugating targeting compounds with TLR7 agonists, generating immune-targeting conjugates (ImmunTacs). GY161, as a representative ImmunTac, was synthesized via chemical conjugation of ibrutinib with a TLR7 agonist. In vitro, GY161 stimulated the production of cytokines by mouse spleen lymphocytes, promoted the maturation of dendritic cells (DCs), and inhibited the growth and induced the apoptosis of B16 melanoma cells by regulating the c-Met/β-catenin pathway. In vivo, GY161 enhanced the frequency of CD8⁺ T cells in spleens and tumors, suppressed the growth of B16 melanoma cell-derived tumors and prolonged the survival time of mice. In summary, GY161 could prevent melanoma progression through direct tumor killing and by triggering specific immunity. These results strongly suggest that ImmunTacs are a reliable and promising strategy for developing small molecule immunogenic anticancer drugs.

Vitamin D Receptor Expression and its Clinical Significance in Papillary Thyroid Cancer

Objective: This study aimed to evaluate the association between vitamin D receptor (an essential component in the vitamin D signaling pathway) and serum vitamin D as well as its clinical significance in papillary thyroid cancer. Methods: This prospective cohort study comprised patients with thyroid tumors who visited our hospital, from 2017 to 2018. The level of vitamin D receptor expression from thyroid tissue was measured in patients with thyroid tumor and evaluated for correlation with serum vitamin D levels and clinicopathologic characteristics of papillary thyroid cancer. Data from 501 patients with papillary thyroid cancer from The Cancer Genome Atlas database were analyzed. Results: Increased vitamin D receptor protein and mRNA expression were observed in papillary thyroid cancer compared to those in normal and benign tissues. Lower vitamin D receptor protein expression was associated with high TNM stage papillary thyroid cancer and low p21 protein expression. Lower relative vitamin D receptor mRNA expression in papillary thyroid cancer was associated with low serum 25-hydroxyvitamin D level. The Cancer Genome Atlas database showed a positive correlation among mRNA expression of vitamin D receptor, CYP24A1, and p21. Conclusions: An association between decreased vitamin D receptor protein expression and advanced stage papillary thyroid cancer, and a correlation between low vitamin D receptor mRNA expression with low serum 25-hydroxyvitamin D level was observed. Low vitamin D receptor expression in papillary thyroid cancer was shown to positively correlate with low serum vitamin D level and disease aggressiveness.

Thyroid Hormone Nuclear Receptor TRα1 and Canonical WNT Pathway Cross-Regulation in Normal Intestine and Cancer

A pivotal role of thyroid hormones and their nuclear receptors in intestinal development and homeostasis have been described, whereas their involvement in intestinal carcinogenesis is still controversial. In this perspective article we briefly summarize the recent advances in this field and present new data regarding their functional interaction with one of the most important signaling pathway, such as WNT, regulating intestinal development and carcinogenesis. These complex interactions unveil new concepts and will surely be of importance for translational research.

Aloe-emodin inhibits the proliferation, migration, and invasion of melanoma cells via inactivation of the Wnt/beta-catenin signaling pathway

BACKGROUND

Aloe-emodin is reported as a potential cancer therapeutic agent due to its inhibition of the proliferation, migration, and invasion of cancer cells. This study aimed to confirm the effects of aloe-emodin on the progression of melanoma and identify the underlying molecular mechanisms.

METHODS

The effects of aloe-emodin treatment (concentrations ranging from 0 to 25 µg, 48 h) on proliferation, apoptosis, distribution of cell cycle, migration, and invasion were detected by performing Cell Counting Kit-8 (CCK-8) assay, colony formation assay, flow cytometry, wound healing assay, and Transwell invasion experiments. Rescue experiments were carried out by overexpression of β-catenin to verify the role of β-catenin in the inhibition of melanoma by aloe-emodin. The analysis was carried out at the animal level by constructing tumor-bearing nude mice model.

RESULTS

The results showed that aloe-emodin prominently reduced the proliferation, migration, and invasion of melanoma cells. Additionally, it was found that aloe-emodin significantly enhanced the cell apoptosis and induced G2 phase arrest of melanoma cells via enhancing the expressions of cleaved-caspase3, bax, and reducing cyclinD1, c-myc, and bcl-2. In addition, aloe-emodin could also inhibit Wnt3a levels, and promote GSK3-beta and beta-catenin phosphorylation. In vivo experiments also showed that overexpression of beta-catenin reversed the effects of aloe-emodin on tumor growth.

CONCLUSIONS

In conclusion, our findings indicated that aloe-emodin might prominently inhibit the tumor growth and metastasis of melanoma via the Wnt/beta-catenin signaling pathway in vitro. Therefore, aloe-emodin may serve as a potential drug for the clinical treatment of melanoma.

In Vitro Non-Genomic Effects of Calcifediol on Human Preosteoblastic Cells

Several recent studies have demonstrated that the direct precursor of vitamin D₃, the calcifediol [25(OH)D₃], through the binding to the nuclear vitamin D receptor (VDR), is able to regulate the expression of many genes involved in several cellular processes. Considering that itself may function as a VDR ligand, although with a lower affinity, respect than the active form of vitamin D, we have assumed that 25(OH)D₃ by binding the VDR could have a vitamin’s D₃ activity such as activating non-genomic pathways, and in particular we selected mesenchymal stem cells derived from human adipose tissue (hADMSCs) for the in vitro assessment of the intracellular Ca²⁺ mobilization in response to 25(OH)D₃. Our result reveals the ability of 25(OH)D₃ to activate rapid, non-genomic pathways, such as an increase of intracellular Ca²⁺ levels, similar to what observed with the biologically active form of vitamin D₃. hADMSCs loaded with Fluo-4 AM exhibited a rapid and sustained increase in intracellular Ca²⁺ concentration as a result of exposure to 10⁻⁵ M of 25(OH)D₃. In this work, we show for the first time the in vitro ability of 25(OH)D₃ to induce a rapid increase of intracellular Ca²⁺ levels in hADMSCs. These findings represent an important step to better understand the non-genomic effects of vitamin D₃ and its role in endocrine system.

The Role of the Vitamin D Receptor in the Pathogenesis, Prognosis, and Treatment of Cutaneous Melanoma

Melanoma is the malignant transformation of melanocytes and represents the most lethal form of skin cancer. While early-stage melanoma localized to the skin can be cured with surgical excision, metastatic melanoma often requires a multi-pronged approach and even then can exhibit treatment resistance. Understanding the molecular mechanisms involved in the pathogenesis of melanoma could lead to novel diagnostic, prognostic, and therapeutic strategies to ultimately decrease morbidity and mortality. One emerging candidate that may have value as both a prognostic marker and in a therapeutic context is the vitamin D receptor (VDR). VDR is a nuclear steroid hormone receptor activated by 1,25 dihydroxy-vitamin D3 [calcitriol, 1,25(OH)2D3]. While 1,25 dihydroxy-vitamin D3 is typically thought of in relation to calcium metabolism, it also plays an important role in cell proliferation, differentiation, programmed-cell death as well as photoprotection. This review discusses the role of VDR in the crosstalk between keratinocytes and melanocytes during melanomagenesis and summarizes the clinical data regarding VDR polymorphisms, VDR as a prognostic marker, and potential uses of vitamin D and its analogs as an adjuvant treatment for melanoma.

Osteoinductive and antimicrobial mechanisms of graphene-based materials for enhancing bone tissue engineering

Graphene-based materials (GMs) have great application prospects in bone tissue engineering due to their osteoinductive ability and antimicrobial activity. GMs induce osteogenic differentiation through several mechanisms and pathways in bone tissue engineering. First of all, the surface and high hardness of the porous folds of graphene or graphene oxide (GO) can generate mechanical stimulation to initiate a cascade of reactions that promote osteogenic differentiation without any chemical inducers. In addition, change of the extracellular matrix (ECM), regulation of macrophage polarization, the oncostatin M (OSM) signaling pathway, the MAPK signaling pathway, the BMP signaling pathway, the Wnt/β-catenin signaling pathway, and other pathways are involved in GMs' regulation of osteogenesis. In bone tissue engineering, GMs prevent the formation of microbial biofilms mainly through preventing microbial adhesion and killing them. The former is mainly achieved by reducing surface free energy (SFE) and increasing hydrophobicity. The latter mainly includes oxidative stress and photothermal/photodynamic effects. Graphene and its derivatives (GDs) are mainly combined with bioactive ceramic materials, metal materials and macromolecular polymers to play an antimicrobial effect in bone tissue engineering. Concentration, number of layers, and type of GDs often affect the antimicrobial activity of GMs. In this paper, we reviewed relevant osteoinductive and antimicrobial mechanisms of GMs and their applications in bone tissue engineering.

Vitamin D suppressed gastric cancer cell growth through downregulating CD44 expression in vitro and in vivo

OBJECTIVES

Vitamin D deficiency was found to be associated with increased risk for gastric cancer (GC). We previously found that vitamin D inhibited GC cell growth in vitro. However, the in vivo antitumor effect of vitamin D in GC as well as the underlying mechanisms are not well understood. The aim of this study was to investigate the anticancer effect of vitamin D on GC both in vitro and in vivo.

METHODS

Human GC cells MKN45, MKN28, and KATO III were used. The expressions of vitamin D receptor (VDR) and CD44 were downregulated by using predesigned siRNA molecules. Cell viability was evaluated by methyl thiazolyl tetrazolium assay. Soft agar assay was used for colony formation of GC cells. Flow cytometry was used to assess CD44-positive cell population. CD44^high cancer cells were enriched by using anti-CD44-conjugated magnetic microbeads. Quantitative real-time polymerase chain reaction and Western blot were performed to detect gene and protein expressions, respectively. Clinical samples were collected for evaluation of the correlation of VDR and CD44 expression. Orthotopic tumor-bearing mice were established to evaluate the antitumor effect of vitamin D.

RESULTS

The results showed that the active form of vitamin D, 1,25(OH)₂D₃, had a remarkable inhibitory effect in CD44-expressing human GC MKN45 and KATO III cells, but not in CD44-null MKN28 cells. The gene expressions of CD44 and VDR in GC cell lines and GC patient tissues were positively correlated. Furthermore, 1,25(OH)₂D₃ suppressed MKN45 and KATO III cell growth through VDR-induced suppression of CD44. Additionally, we demonstrated that 1,25(OH)₂D₃ inhibited Wnt/β-catenin signaling pathway, which might lead to the downregulation of CD44. In an orthotopic GC nude mice model, both oral intake of vitamin D and intraperitoneal injection with 1,25(OH)₂D₃ could significantly inhibit orthotopic GC growth and CD44 expression in vivo.

CONCLUSION

To our knowledge, this study provided the first evidence that vitamin D suppressed GC cell growth both in vitro and in vivo through downregulating CD44. The present study sheds light on repurposing vitamin D as a potential therapeutic agent for GC prevention and treatment.

SFPQ promotes an oncogenic transcriptomic state in melanoma

The multifunctional protein, splicing factor, proline- and glutamine-rich (SFPQ) has been implicated in numerous cancers often due to interaction with coding and non-coding RNAs, however, its role in melanoma remains unclear. We report that knockdown of SFPQ expression in melanoma cells decelerates several cancer-associated cell phenotypes, including cell growth, migration, epithelial to mesenchymal transition, apoptosis, and glycolysis. RIP-seq analysis revealed that the SFPQ-RNA interactome is reprogrammed in melanoma cells and specifically enriched with key melanoma-associated coding and long non-coding transcripts, including SOX10, AMIGO2 and LINC00511 and in most cases SFPQ is required for the efficient expression of these genes. Functional analysis of two SFPQ-enriched lncRNA, LINC00511 and LINC01234, demonstrated that these genes independently contribute to the melanoma phenotype and a more detailed analysis of LINC00511 indicated that this occurs in part via modulation of the miR-625-5p/PKM2 axis. Importantly, analysis of a large clinical cohort revealed that elevated expression of SFPQ in primary melanoma tumours may have utility as a prognostic biomarker. Together, these data suggest that SFPQ is an important driver of melanoma, likely due to SFPQ-RNA interactions promoting the expression of numerous oncogenic transcripts.

Knocking out the Vitamin D Receptor Enhances Malignancy and Decreases Responsiveness to Vitamin D3 Hydroxyderivatives in Human Melanoma Cells

Simple Summary

Active forms of vitamin D3, including 1,25(OH)₂D3, 20(OH)D3 and 1,20(OH)₂D3, inhibited cell proliferation, migration rate and the ability to form colonies and spheroids in the wild-type melanoma cell line, while cells with the vitamin D receptor (VDR) silenced showed an increased but not complete resistance to their action. Furthermore, silencing of the VDR in melanoma cells enhanced their proliferation as well as spheroid and colony formation and increased their migration rate. Previous clinicopathological studies have shown an inverse correlation between VDR expression, melanoma progression and poor outcome of the disease. Thus, the expression of VDR is not only necessary for the inhibition of melanoma growth by active forms of vitamin D, but the VDR can also function as a melanoma tumor suppressor gene.

Abstract

Vitamin D3 is not only involved in calcium and phosphate metabolism in humans, but it can also affect proliferation and differentiation of normal and cancer cells, including melanoma. The mechanism of the anti-cancer action of vitamin D3 is not fully understood. The nuclear vitamin D receptor (VDR) is crucial for the phenotypic effects of vitamin D hydroxyderivatives. VDR expression shows an inverse correlation with melanoma progression and poor outcome of the disease. In this study we knocked out the VDR in a human melanoma cell line using CRISPR methodology. This enhanced the proliferation of melanoma cells grown in monolayer culture, spheroids or colonies and their migration. Activated forms of vitamin D, including classical 1,25(OH)₂D3, 20(OH)D3 and 1,20(OH)₂D3, inhibited cell proliferation, migration rate and the ability to form colonies and spheroids in the wild-type melanoma cell line, while VDR KO cells showed a degree of resistance to their action. These results indicate that expression of VDR is important for the inhibition of melanoma growth induced by activated forms of vitamin D. In conclusion, based on our previous clinicopathological analyses and the current study, we suggest that the VDR can function as a melanoma tumor suppressor gene.

Epithelial-mesenchymal transition: When tumor cells meet myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous myeloid cell population characterized by protumoral functions in the tumor immune network. An increasing number of studies have focused on the biological functions of MDSCs in tumor immunity. Epithelial-mesenchymal transition (EMT) is a cellular plasticity process accompanied by a loss of epithelial phenotypes and an acquisition of mesenchymal phenotypes. In general, tumor cells that undergo EMT are more likely to invade and metastasize. Recently, extensive evidence suggests that EMT is closely related to a highly immunosuppressive environment. This review will summarize the immunosuppressive capacities of MDSC subsets and their distinct role in tumor EMT and further discuss immunotherapy for tumor EMT by targeting MDSCs.

Vitamin D sufficiency enhances differentiation of patient-derived prostate epithelial organoids

Vitamin D is an essential steroid hormone that regulates systemic calcium homeostasis and cell fate decisions. The prostate gland is hormonally regulated, requiring steroids for proliferation and differentiation of secretory luminal cells. Vitamin D deficiency is associated with an increased risk of lethal prostate cancer, which exhibits a dedifferentiated pathology, linking vitamin D sufficiency to epithelial differentiation. To determine vitamin D regulation of prostatic epithelial differentiation, patient-derived benign prostate epithelial organoids were grown in vitamin D-deficient or -sufficient conditions. Organoids were assessed by phenotype and single-cell RNA sequencing. Mechanistic validation demonstrated that vitamin D sufficiency promoted organoid growth and accelerated differentiation by inhibiting canonical Wnt activity and suppressing Wnt family member DKK3. Wnt and DKK3 were also reduced by vitamin D in prostate tissue explants by spatial transcriptomics. Wnt dysregulation is a known contributor to aggressive prostate cancer, thus findings further link vitamin D deficiency to lethal disease.

Combined Administration of Vitamin D3 and Geniposide Is Less Effective than Single Use of Vitamin D3 or Geniposide in the Treatment of Ulcerative Colitis

With the increasing incidence of ulcerative colitis (UC) in China, Chinese medicinal herbs or relatively active compounds are widely applied in treating UC. These medicines may be combined with other therapeutic agents such as vitamin D₃. Nevertheless, the efficacy of these combinations for UC is unclear. Geniposide is an active component in many Chinese herbal medicines. It could ameliorate dextran sulfate sodium (DSS)-induced colitis in mice. This study was designed to determine the efficacy and mechanism of the single use and combination of geniposide and vitamin D₃ on a mouse model of acute colitis. Data showed that a single administration of geniposide (2 mg/kg) or vitamin D₃ (4 IU/day) could significantly improve the symptoms of UC and relieve colon damage. Geniposide and vitamin D could significantly decrease the levels of TNF-α and IL-6 in serum and colon, and increase the level of IL-10 in the colon. However, the combined treatment of geniposide (2 mg/kg) and vitamin D₃ (4 IU/day) exerted less beneficial effects on UC in mice, indicating by less improvement of UC symptoms, colon damage, and inflammatory infiltration. The combination only downregulated the level of TNF-α in serum and IL-6 in the colon. Our data further demonstrated that geniposide could inhibit the activation of p38 MAPK and then restrict the vitamin D receptor signaling stimulated by vitamin D₃. These results implied that the combination of geniposide and vitamin D₃ might not be an ideal combined treatment for acute colitis, and the combination of vitamin D supplementary and geniposide (or herbal medicines rich in geniposide) need more evaluation before being applied to treat UC in clinic.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Wnt and Vitamin D at the Crossroads in Solid Cancer

Simple Summary

The Wnt/β-catenin signaling pathway is aberrantly activated in most colorectal cancers and less frequently in a variety of other solid neoplasias. Many epidemiological and experimental studies and some clinical trials suggest an anticancer action of vitamin D, mainly against colorectal cancer. The aim of this review was to analyze the literature supporting the interference of Wnt/β-catenin signaling by the active vitamin D metabolite 1α,25-dihydroxyvitamin D₃. We discuss the molecular mechanisms of this antagonism in colorectal cancer and other cancer types. Additionally, we summarize the available data indicating a reciprocal inhibition of vitamin D action by the activated Wnt/β-catenin pathway. Thus, a complex mutual antagonism between Wnt/β-catenin signaling and the vitamin D system seems to be at the root of many solid cancers.

Abstract

Abnormal activation of the Wnt/β-catenin pathway is common in many types of solid cancers. Likewise, a large proportion of cancer patients have vitamin D deficiency. In line with these observations, Wnt/β-catenin signaling and 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active vitamin D metabolite, usually have opposite effects on cancer cell proliferation and phenotype. In recent years, an increasing number of studies performed in a variety of cancer types have revealed a complex crosstalk between Wnt/β-catenin signaling and 1,25(OH)₂D₃. Here we review the mechanisms by which 1,25(OH)₂D₃ inhibits Wnt/β-catenin signaling and, conversely, how the activated Wnt/β-catenin pathway may abrogate vitamin D action. The available data suggest that interaction between Wnt/β-catenin signaling and the vitamin D system is at the crossroads in solid cancers and may have therapeutic applications.

The Wnt Signalling Pathway: A Tailored Target in Cancer

Cancer is one of the greatest public health challenges. According to the World Health Organization (WHO), 9.6 million cancer deaths have been reported in 2018. The most common cancers include lung, breast, colorectal, prostate, skin (non-melanoma) and stomach cancer. The unbalance of physiological signalling pathways due to the acquisition of mutations in tumour cells is considered the most common cancer driver. The Wingless-related integration site (Wnt)/β-catenin pathway is crucial for tissue development and homeostasis in all animal species and its dysregulation is one of the most relevant events linked to cancer development and dissemination. The canonical and the non-canonical Wnt/β-catenin pathways are known to control both physiological and pathological processes, including cancer. Herein, the impact of the Wnt/β-catenin cascade in driving cancers from different origin has been examined. Finally, based on the impact of Extracellular Vesicles (EVs) on tumour growth, invasion and chemoresistance, and their role as tumour diagnostic and prognostic tools, an overview of the current knowledge linking EVs to the Wnt/β-catenin pathway is also discussed.

Ensuring universal assessment and management of vitamin D status in melanoma patients at secondary care level: a service improvement project

BACKGROUND/AIMS

Melanoma is the most aggressive skin malignancy with an ever-increasing caseload, especially in the western world. Recently developed immunotherapeutic modalities have substantially improved the prognosis of advanced melanoma. The association between serum levels of vitamin D and prognosis of melanoma has been a focus of ongoing research, with some evidence of vitamin D's potential as an adjunctive modality to immunotherapy. The National Institute for Health and Care Excellence guidelines clearly recommend that assessment of vitamin D levels and relevant advice should be an inherent aspect of the management of patients with melanoma at the secondary care level.

METHOD

A service improvement project was conducted to ensure full compliance of practice in the authors' skin unit with the current National Institute for Health and Care Excellence guidelines on the management of vitamin D status in patients with melanoma.

RESULTS

After two reaudits the unit's practice complied with National Institute for Health and Care Excellence guidelines by using a multidisciplinary team approach.

CONCLUSIONS

The authors propose that the simple and reliable pathway used to achieve and sustain the results could be easily adopted to ensure universal adherence to these guidelines.

Vitamin D receptor(s): In the nucleus but also at membranes?

The genomic actions of the vitamin D are mediated via its biologically most potent metabolite 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂ D₃ ) and the transcription factor vitamin D receptor (VDR). Activation of VDR by 1,25(OH)₂ D₃ leads to change in the expression of more 1000 genes in various human tissues. Based on (epi)genome, transcriptome and crystal structure data the molecular details of this nuclear vitamin D signalling pathway are well understood. Vitamin D is known for its role on calcium homeostasis and bone formation, but it also modulates energy metabolism, innate and adaptive immunity as well as cellular growth, differentiation and apoptosis. The observation of rapid, non-genomic effects of 1,25(OH)₂ D₃ at cellular membranes and in the cytosol initiated the question, whether there are alternative vitamin D-binding proteins in these cellular compartments. So far, the best candidate is the enzyme PDIA3 (protein disulphide isomerase family A member 3), which is found at various subcellular locations. Furthermore, also VDR seems to play a role in membrane-based responses to vitamin D. In this viewpoint, we will dispute whether these rapid, non-genomic pathways are a meaningful addition to the genome-wide effects of vitamin D.

Vitamin D deficiency as a potential risk factor for accelerated aging, impaired hippocampal neurogenesis and cognitive decline: a role for Wnt/β-catenin signaling

Vitamin D is an essential fat-soluble vitamin that participates in several homeostatic functions in mammalian organisms. Lower levels of vitamin D are produced in the older population, vitamin D deficiency being an accelerating factor for the progression of the aging process. In this review, we focus on the effect that vitamin D exerts in the aged brain paying special attention to the neurogenic process. Neurogenesis occurs in the adult brain in neurogenic regions, such as the dentate gyrus of the hippocampus (DG). This region generates new neurons that participate in cognitive tasks. The neurogenic rate in the DG is reduced in the aged brain because of a reduction in the number of neural stem cells (NSC). Homeostatic mechanisms controlled by the Wnt signaling pathway protect this pool of NSC from being depleted. We discuss in here the crosstalk between Wnt signaling and vitamin D, and hypothesize that hypovitaminosis might cause failure in the control of the neurogenic homeostatic mechanisms in the old brain leading to cognitive impairment. Understanding the relationship between vitamin D, neurogenesis and cognitive performance in the aged brain may facilitate prevention of cognitive decline and it can open a door into new therapeutic fields by perspectives in the elderly.

The Cancer-Immune Set Point in Oesophageal Cancer

Immunotherapy has achieved long-term disease control in a proportion of cancer patients, but determinants of clinical benefit remain unclear. A greater understanding of antitumor immunity on an individual basis is needed to facilitate a precision oncology approach. A conceptual framework called the "cancer-immune set point" has been proposed to describe the equilibrium between factors that promote or suppress anticancer immunity and can serve as a basis to understand the variability in clinical response to immune checkpoint blockade. Oesophageal cancer has a high mutational burden, develops from pre-existing chronic inflammatory lesions and is therefore anticipated to be sensitive to immune checkpoint inhibition. However, both tumour- and patient-specific factors including the immune microenvironment, the microbiome, obesity, and host genetics contribute to an immune set point that confers a lower-than-expected response to checkpoint blockade. Immunotherapy is therefore currently confined to latter lines of treatment of advanced disease, with no reliable predictive biomarker of response. In this review, we examine oesophageal cancer in the context of the cancer-immune set point, discuss factors that contribute to response to immunotherapeutic intervention, and propose areas requiring further investigation to improve treatment response.

1α, 25(OH)2D3 regulates agrin-induced acetylcholine receptor clustering through upregulation of rapsyn expression in C2C12 myotubes

The active form of vitamin D (1α, 25-dihydroxyvitamin D3 [1α, 25(OH)2D3], referred to as 1,25D) has been suggested to play a pivotal role in skeletal muscle function and metabolism. However, the mechanisms through which 1,25D functions in this tissue remain to be elucidated. Recent studies have shown that vitamin D signaling regulates neuromuscular maintenance and improves locomotion in mice. In the present study, we examined the effects of 1,25D on neuromuscular synaptogenesis by measuring clustering of acetylcholine receptors (AChRs) in C2C12 myotubes. 1,25D treatment enhanced the agrin-induced AChR clustering in myotubes compared to treatment with agrin alone. Furthermore, siRNA-mediated knockdown of the vitamin D receptor (VDR) decreased the agrin-induced AChR clustering. 1,25D increased the expression of rapsyn, which is necessary for AChR clustering, while demonstrating no effect on other neuromuscular junction-related genes. In addition, rapsyn expression was dependent on 1,25D-VDR signaling. These results suggest that 1,25D-VDR signaling may regulate rapsin expression, resulting in the up-regulation of agrin-induced AChR clustering.

Vitamin D and Ovarian Cancer: Systematic Review of the Literature with a Focus on Molecular Mechanisms

Vitamin D is a lipid soluble vitamin involved primarily in calcium metabolism. Epidemiologic evidence indicates that lower circulating vitamin D levels are associated with a higher risk of ovarian cancer and that vitamin D supplementation is associated with decreased cancer mortality. A vast amount of research exists on the possible molecular mechanisms through which vitamin D affects cancer cell proliferation, cancer progression, angiogenesis, and inflammation. We conducted a systematic review of the literature on the effects of vitamin D on ovarian cancer cell.