1,25-Dihydroxyvitamin D induces the glutamate transporter SLC1A1 and alters glutamate handling in non-transformed mammary cells

Identification of a ferroptosis-related gene signature for prognosis prediction in colorectal cancer patients and relationship with vitamin D

Ferroptosis is a promising colorectal cancer (CRC) treatment strategy; however, its value in prognosis remains at an exploratory stage. Little research has been conducted on vitamin D and ferroptosis, although vitamin D has been shown to inhibit CRC through various mechanisms. A retrospective study was conducted using RNA-seq profiles and corresponding clinical information of CRC patients retrieved from TCGA and GEO databases.We used R package to process and analyze the data. We established the prognostic signature with elastic network regression model. KEGG was used to analyze pathways related to FRGs, and protein-protein interaction(PPI)was used to identify potential interactions with vitamin D. In HCT116 cells, the levels of cysteine (Cys), glutathione (GSH), and reactive oxygen species (ROS) and the expression of ferroptosis marker genes were measured by Western blot and qRT-PCR. Results showed, a prognostic signature containing 39 FRGs was established, and the Area Under Curve (AUC) of the 2nd, 5th, and 8th years were 0.81, 0.81, and 0.78, respectively. There were distinct differences in survival probability between the high- and low-risk groups, and the signature was applicable to stratified survival analysis based on tumor stage. The risk score possessed an independent prognostic value. Importantly, we found that vitamin D receptor (VDR) has a potential relationship with many FRGs, and vitamin D promotes ferroptosis in CRC cells and affects the expression of TP53, MAPK3, and SLC7A11. In summary, a signature with FRGs can effectively predict the prognosis of CRC. Vitamin D can promote ferroptosis in CRC.

Vitamin D regulation of energy metabolism in cancer

Vitamin D exerts anti-cancer effects in recent clinical trials and preclinical models. The actions of vitamin D are primarily mediated through its hormonal form, 1,25-dihydroxyvitamin D (1,25(OH)₂ D). Previous literature describing in vitro studies has predominantly focused on the anti-tumourigenic effects of the hormone, such as proliferation and apoptosis. However, recent evidence has identified 1,25(OH)₂ D as a regulator of energy metabolism in cancer cells, where requirements for specific energy sources at different stages of progression are dramatically altered. The literature suggests that 1,25(OH)₂ D regulates energy metabolism, including glucose, glutamine and lipid metabolism during cancer progression, as well as oxidative stress protection, as it is closely associated with energy metabolism. Mechanisms involved in energy metabolism regulation are an emerging area in which vitamin D may inhibit multiple stages of cancer progression.

The Role of Lipidomics in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome commonly diagnosed in early childhood; it is usually characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal with loss in communication skills. Its development may be affected by a variety of environmental and genetic factors. Trained physicians diagnose and evaluate the severity of ASD based on clinical evaluations of observed behaviors. As such, this approach is inevitably dependent on the expertise and subjective assessment of those administering the clinical evaluations. There is a need to identify objective biological markers associated with diagnosis or clinical severity of the disorder. Several important issues and concerns exist regarding the diagnostic competence of the many abnormal plasma metabolites produced in the different biochemical pathways evaluated in individuals with ASD. The search for high-performing bio-analytes to diagnose and follow-up ASD development is still a major target in medicine. Dysregulation in the oxidative stress response and proinflammatory processes are major etiological causes of ASD pathogenesis. Furthermore, dicarboxylic acid metabolites, cholesterol-related metabolites, phospholipid-related metabolites, and lipid transporters and mediators are impaired in different pathological conditions that have a role in the ASD etiology. A mechanism may exist by which pro-oxidant environmental stressors and abnormal metabolites regulate clinical manifestations and development of ASD.

Vitamin D deficiency exacerbates Alzheimer-like pathologies by reducing antioxidant capacity

Vitamin D (VD) deficiency is prevalent among aging people and Alzheimer's disease (AD) patients. However, the roles of VD deficiency in the pathology of AD remain largely unexplored. In this study, APP/PS1 mice were fed a VD-deficient diet for 13 weeks to evaluate the effects of VD deficiency on the learning and memory functions and the neuropathological characteristics of the mice. Our study revealed that VD deficiency accelerated cognitive impairment in the APP/PS1 mice. Mechanistic studies revealed that VD deficiency promoted glial activation and increased inflammatory factor secretion. Furthermore, VD deficiency increased the production and deposition of Aβ by elevating the expression levels of amyloid precursor protein (APP) and β-site APP cleavage enzyme 1 (BACE1). In addition, VD deficiency increased the phosphorylation of Tau at Thr181, Thr205 and Ser396 by increasing the activities of cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3α/β (GSK3α/β) and promoted synaptic dystrophy and neuronal loss. All these effects of VD deficiency may be ascribed to enhanced oxidative stress via the downregulation of superoxide dismutase 1 (SOD1), glutathione peroxidase 4 (GPx4) and cystine/glutamate exchanger (xCT). Taken together, our data suggest that VD deficiency exacerbates Alzheimer-like pathologies via promoting inflammatory stress, increasing Aβ production and elevating Tau phosphorylation by decreasing antioxidant capacity in the brains of APP/PS1 mice. Hence, rescuing the VD status of AD patients should be taken into consideration during the treatment of AD.

Vitamin D regulates prostate cell metabolism via genomic and non-genomic mitochondrial redox-dependent mechanisms

Vitamin D deficiency has been associated with increased risk for aggressive prostate cancer (PCa). Prostate epithelium has a unique metabolism compared to other tissues. Normal prostate exhibits low levels of mitochondrial respiration and there is a metabolic switch to increased oxidative phosphorylation in PCa. 25-hydroxyvitamin D (25(OH)D) is the major circulating form of vitamin D and is used clinically to determine vitamin D status. Activation of 25(OH)D to the transcriptionally active form, 1,25(OH)₂D occurs via a reduction-oxidation (redox) reaction within the mitochondria that is catalyzed by the P450 enzyme, CYP27B1. We sought to determine if hydroxylation of 25(OH)D by CYP27B1 contributes to non-genomic activity of vitamin D by altering the redox-dependent state of the mitochondria in benign prostate epithelial cells. Exposure to 25(OH)D produced a transient pro-oxidant effect and change in mitochondrial membrane potential that was dependent on CYP27B1. Extended exposure ultimately suppressed mitochondrial respiration, consistent with a protective effect of 25(OH)D in supporting benign prostate metabolism. To model physiologically relevant changes in vitamin D, cells were cultured in constant 25(OH)D then changed to high or deficient concentrations. This model also incurred a biphasic effect with a pro-oxidant shift after short exposure followed by decreased respiration after 16 h. Several genes involved in redox cycling and Mitochondrial Health were regulated by 25(OH)D in these cells. These results indicate a secondary non-genomic mechanism for vitamin D to contribute to prostate cell health by supporting normal mitochondrial respiration.

Glutamate transporter SLC1A1 is associated with clear cell renal cell carcinoma

Background/aim

This study aimed to comparatively analyze the expression levels of the SLC1A1 gene in renal specimens from tumors and adjacent healthy kidney tissues of patients with clear cell renal cell carcinoma (ccRCC).

Material and methods

Nineteen patients diagnosed with ccRCC were included in the study. The expression levels of the SLC1A1 and GAPDH genes were measured in tumor and formalin-fixed paraffin-embedded (FFPE) tissue specimens from the adjacent healthy kidney of each subject. Via the GEPIA database, the distribution of SLC1A1 gene expressions in ccRCC and healthy kidney tissues was obtained. The relative expression of SLC1A1 was evaluated for the association with the clinical parameters of the patients.

Results

The expression of the SLC1A1 gene was significantly higher in males than females (P = 0.029). Also, there were statistically significant associations between stages II–IV and Fuhrman grades 2–4 with respect to SLC1A1 gene expression (P < 0.001 for both). Moreover, low levels of red blood cell and hemoglobin counts were significantly associated with the SLC1A1 expression (P < 0.001 and P = 0.005, respectively). The expression of the SLC1A1 gene in tumor tissues increased approximately 3 times compared with normal kidney tissues (P < 0.05). According to the GEPIA database, SLC1A1 gene expression is significantly higher in ccRCC patients than healthy persons (P = 0.01).

Conclusion

The change in the expression of SLC1A1 may be crucial for ccRCC pathophysiology.

Grainyhead-like 2 Reverses the Metabolic Changes Induced by the Oncogenic Epithelial-Mesenchymal Transition: Effects on Anoikis

Resistance to anoikis is a prerequisite for tumor metastasis. The epithelial-to-mesenchymal transition (EMT) allows tumor cells to evade anoikis. The wound-healing regulatory transcription factor Grainyhead-like 2 (GRHL2) suppresses/reverses EMT, accompanied by suppression of the cancer stem cell (CSC) phenotype and by resensitization to anoikis. Here, the effects of GRHL2 upon intracellular metabolism in the context of reversion of the EMT/CSC phenotype, with a view toward understanding how these effects promote anoikis sensitivity, were investigated. EMT enhanced mitochondrial oxidative metabolism. Although this was accompanied by higher accumulation of superoxide, the overall level of reactive oxygen species (ROS) declined, due to decreased hydrogen peroxide. Glutamate dehydrogenase 1 (GLUD1) expression increased in EMT, and this increase, via the product α-ketoglutarate (α-KG), was important for suppressing hydrogen peroxide and protecting against anoikis. GRHL2 suppressed GLUD1 gene expression, decreased α-KG, increased ROS, and sensitized cells to anoikis.

IMPLICATIONS

These results demonstrate a mechanistic role for GRHL2 in promoting anoikis through metabolic alterations. Mol Cancer Res; 14(6); 528-38. ©2016 AACR.