The GLUT-1 XbaI gene polymorphism is associated with vascular calcifications in nondiabetic uremic patients

Phenotypic plasticity of vascular smooth muscle cells in vascular calcification: Role of mitochondria

Vascular calcification (VC) is an important hallmark of cardiovascular disease, the osteo-/chondrocyte phenotype differentiation of vascular smooth muscle cells (VSMCs) is the main cause of vascular calcification. Accumulating evidence shows that mitochondrial dysfunction may ultimately be more detrimental in the VSMCs calcification. Mitochondrial participate in essential cellular functions, including energy production, metabolism, redox homeostasis regulation, intracellular calcium homeostasis, apoptosis, and signal transduction. Mitochondrial dysfunction under pathological conditions results in mitochondrial reactive oxygen species (ROS) generation and metabolic disorders, which further lead to abnormal phenotypic differentiation of VSMCs. In this review, we summarize existing studies targeting mitochondria as a treatment for VC, and focus on VSMCs, highlighting recent progress in determining the roles of mitochondrial processes in regulating the phenotype transition of VSMCs, including mitochondrial biogenesis, mitochondrial dynamics, mitophagy, mitochondrial energy metabolism, and mitochondria/ER interactions. Along these lines, the impact of mitochondrial homeostasis on VC is discussed.

Polymorphism in the HaeIII single nucleotide polymorphism of the SLC2A1 gene and cardiovascular disease in the early type 2 diabetes mellitus

INTRODUCTION

SLC2A1 polymorphism may play a role in the smooth muscle cell proliferation and extracellular matrix synthesis in vessels. However, the role of SLC2A1 polymorphism on diabetic cardiovascular disease (CVD) have not yet been identified. In this study, we aimed to investigate the association between SLC2A1 HaeIII polymorphism and CVD in Korean patients with type 2 diabetes mellitus (T2DM) according to disease duration.

METHODS

A total of 846 patients with T2DM who visited the Chungbuk National University Hospital were investigated. The HaeIII polymorphism of SLC2A1 gene was determined by real time polymerase chain reaction method. Genotyping results were presented GG, AG, or AA. Subgroup analysis was performed according to duration of T2DM (⩽10, 11-20, >20 years).

RESULTS

The AA genotype was significantly associated with higher prevalence of CVD in patients with DM duration less than 10 years (26.3% vs 9.2%, p = 0.014). There was no significant association between SLC2A1 HaeIII polymorphism and other diabetic complications including, retinopathy, nephropathy, neuropathy, cerebrovascular disease, and peripheral artery disease.

CONCLUSIONS

The SLC2A1 HaeIII polymorphism was associated with CVD in Korean patients with T2DM with short disease duration.

Advanced glycation end products accelerate calcification in VSMCs through HIF-1α/PDK4 activation and suppress glucose metabolism

Arterial media calcification is associated with diabetes mellitus. Previous studies have shown that advanced glycation end products (AGEs) are responsible for vascular smooth muscle cell (VSMC) calcification, but the underlying mechanisms remain unclear. Hypoxia-inducible factor-1α (HIF-1α), one of the major factors during hypoxia, and pyruvate dehydrogenase kinase 4 (PDK4), an important mitochondrial matrix enzyme in cellular metabolism shift, have been reported in VSMC calcification. The potential link among HIF-1α, PDK4, and AGEs-induced vascular calcification was investigated in this study. We observed that AGEs elevated HIF-1α and PDK4 expression levels in a dose-dependent manner and that maximal stimulation was attained at 24 h. Two important HIF-1α-regulated genes, vascular endothelial growth factor A (VEGFA) and glucose transporter 1 (GLUT-1), were significantly increased after AGEs exposure. Stabilization or nuclear translocation of HIF-1α increased PDK4 expression. PDK4 inhibition attenuated AGEs-induced VSMC calcification, which was evaluated by measuring the calcium content, alkaline phosphatase (ALP) activity and runt-related transcription factor 2 (RUNX2) expression levels and by Alizarin red S staining. In addition, the glucose consumption, lactate production, key enzymes of glucose metabolism and oxygen consumption rate (OCR) were decreased during AGEs-induced VSMC calcification. In conclusion, this study suggests that AGEs accelerate vascular calcification partly through the HIF-1α/PDK4 pathway and suppress glucose metabolism.

An analysis of the polymorphisms of the GLUT1 gene in urothelial cell carcinomas of the bladder and its correlation with p53, Ki67 and GLUT1 expressions

Frequencies of two glucose transporter 1 (GLUT1) single-nucleotide polymorphisms (SNPs) (XbaI G>T and HaeIII T>C) were studied with urothelial cell carcinomas of the bladder (UCC) and 204 normal persons. And the expression of the p53, Ki67 and GLUT1 was assayed by immunohistochemistry. The frequency of the TT genotype and T allele of the XbaI G>T SNP was decreased in the patients with UCC. The frequency of the CC genotype and C allele of the HaeIII T>C SNP was decreased in the patients with UCC. The GLUT1 XbaI genotype GG was more frequent in higher tumor stage and higher tumor grade patients. In the XbaI G>T SNP, the GG genotype was significantly related to higher Remmele immunoreactive score (IRS) of Ki67 and higher IRS of GLUT1. In conclusion, the TT genotype in XbaI G>T SNP and CC genotype of HaeIII T>C SNP may have protective effect in the carcinogenesis process of UCC. In the XbaI G>T SNP, the GG genotype of was positively related to tumor proliferation, glucose metabolism, tumor grade and stage. Therefore, the variant might become a possible proliferation-related prognostic factor for UCC.

O-linked β-N-acetylglucosamine transferase directs cell proliferation in idiopathic pulmonary arterial hypertension

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is a cardiopulmonary disease characterized by cellular proliferation and vascular remodeling. A more recently recognized characteristic of the disease is the dysregulation of glucose metabolism. The primary link between altered glucose metabolism and cell proliferation in IPAH has not been elucidated. We aimed to determine the relationship between glucose metabolism and smooth muscle cell proliferation in IPAH.

METHODS AND RESULTS

Human IPAH and control patient lung tissues and pulmonary artery smooth muscle cells (PASMCs) were used to analyze a specific pathway of glucose metabolism, the hexosamine biosynthetic pathway. We measured the levels of O-linked β-N-acetylglucosamine modification, O-linked β-N-acetylglucosamine transferase (OGT), and O-linked β-N-acetylglucosamine hydrolase in control and IPAH cells and tissues. Our data suggest that the activation of the hexosamine biosynthetic pathway directly increased OGT levels and activity, triggering changes in glycosylation and PASMC proliferation. Partial knockdown of OGT in IPAH PASMCs resulted in reduced global O-linked β-N-acetylglucosamine modification levels and abrogated PASMC proliferation. The increased proliferation observed in IPAH PASMCs was directly impacted by proteolytic activation of the cell cycle regulator, host cell factor-1.

CONCLUSIONS

Our data demonstrate that hexosamine biosynthetic pathway flux is increased in IPAH and drives OGT-facilitated PASMC proliferation through specific proteolysis and direct activation of host cell factor-1. These findings establish a novel regulatory role for OGT in IPAH, shed a new light on our understanding of the disease pathobiology, and provide opportunities to design novel therapeutic strategies for IPAH.

The XbaI G>T polymorphism of the glucose transporter 1 gene modulates 18F-FDG uptake and tumor aggressiveness in breast cancer

We investigated the relevance of single-nucleotide polymorphisms (SNPs) in the glucose transporter 1 (GLUT1) gene to the uptake of (18)F-FDG and tumor aggressiveness in breast cancer.

METHODS

In 52 individuals with breast cancer, a diagnostic PET/CT scan was obtained, and the standardized uptake value was determined as a measure of (18)F-FDG uptake using a region-of-interest technique. Three GLUT1 SNPs (XbaI G>T, HpyCH4V A>T, and HaeIII T>C) were investigated in genomic DNA that was isolated from the paraffin-embedded specimens of all patients. Tumors were typed and graded according to the World Health Organization classifications.

RESULTS

The GG genotype of the XbaI G>T SNP was associated with increased tumor uptake of (18)F-FDG, with a mean standardized uptake value of 11.7 (TT/GT genotypes, 5.9; P = 0.03). Furthermore, the GG genotype was positively related to enhanced tumor proliferation (mitotic count, P = 0.01). In line with this finding, the GG genotype was absent in grade 1 carcinomas and increasingly prevalent in tumors with higher malignancy (grade 2, 28.0%; grade 3, 50%; P = 0.04).

CONCLUSION

This study found that the XbaI G>T SNP of the GLUT1 gene is associated with an increased (18)F-FDG uptake and a more advanced tumor grade or growth in breast cancer. Thus, this genetic variant might favor aggressive phenotypes by modulating the efficiency of cancer cells to recruit glucose and escalate growth rate, suggesting the XbaI G>T SNP as a proliferation-related prognostic factor.