Diabetes mellitus induces endothelial dysfunction and oxidative stress, contributing to the development of vascular complications. Although metformin exerts well-established vasculoprotective and antioxidant effects, the molecular mechanisms underlying these actions remain incompletely understood. Novel miR-1133 was previously identified as a metformin-responsive putative microRNA (miRNA), and bioinformatic analysis identified PIK3CA as a biologically plausible candidate target for further investigation. This study investigated the functional significance of novel miR-1133 in the antioxidant effects of metformin in hyperglycemia-induced human umbilical vein endothelial cells (HUVECs). HUVECs were exposed to normal glucose (5.5 mmol/L), hyperglycemia (33.3 mmol/L), or hyperglycemia supplemented with metformin (10 μM) for 24 h. Metformin-treated hyperglycemic HUVECs were subsequently transfected with a novel miR-1133 mimic during continued hyperglycemic and metformin exposure. PIK3CA expression and oxidative stress markers, including reactive oxygen species (ROS), superoxide dismutase (SOD), and 8-hydroxy-2′-deoxyguanosine (8-OHdG), were evaluated. Hyperglycemia increased novel miR-1133 expression, whereas metformin reduced its expression. Metformin treatment was associated with increased PIK3CA mRNA and protein expression, reduced ROS and 8-OHdG levels, and increased SOD expression and activity. Novel miR-1133 mimic transfection was associated with reduced PIK3CA expression, increased ROS and 8-OHdG levels, and decreased SOD expression and activity compared with the corresponding transfection control. Collectively, these findings demonstrate that metformin attenuates oxidative stress in hyperglycemia-induced endothelial cells and overall provide the first functional characterization of novel miR-1133. The reciprocal changes in PIK3CA expression and oxidative stress observed following novel miR-1133 mimic transfection suggest that novel miR-1133 may represent a candidate mediator of the endothelial antioxidant responses associated with metformin. Further studies are required to validate the direct interaction between novel miR-1133 and PIK3CA and to elucidate the underlying molecular mechanisms.

Offspring of hypertensive disorders of pregnancies (HDP) exhibit early-life endothelial dysfunction and have an elevated susceptibility to hypertension during adulthood which is potentially mediated by microRNA (miRNA), a key regulator of gene expression. RNA sequencing showed that miR-196a-5p was significantly upregulated in HUVEC exposed to HDP and may regulate angiogenesis in endothelial cells. Therefore, this study aims to elucidate the role of miR-196a-5p in regulating angiogenesis in HUVEC exposed to HDP. miR-196a-5p expression was validated by stem-loop RT-qPCR. Predicted target genes were identified using four algorithms, miRWalk, miRDB, TargetScan, and DIANA-microT-CDS, focusing on angiogenesis-related genes. Protein expression was confirmed through ELISA. Stem-loop RT-qPCR showed that miR-196a-5p expression was significantly upregulated in HDP HUVEC. Bioinformatic analysis revealed that the PDGFRA gene, a key regulator for angiogenesis, was significantly enriched. Overexpression of miR-196a-5p significantly downregulated PDGFRA, VEGF, and bFGF in HDP HUVEC, whereas its suppression upregulated these genes significantly. The ELISA result confirmed the corresponding changes at the protein level. However, PDGFRA protein levels increased with miR-196a-5p overexpression and decreased with its inhibition. Collectively, the results indicate that miR-196a-5p may have a regulatory effect on PDGFRA, VEGF, and bFGF that is associated with angiogenesis, and the modifications could be beneficial in future epigenetic targeted therapy.

Background: Diabetes mellitus is characterized by chronic hyperglycemia, which promotes oxidative stress and endothelial dysfunction. MicroRNAs (miRNAs) have emerged as important regulators of diabetic vascular complications. Our previous RNA-sequencing study identified putative novel miR-1133 as an upregulated miRNA in hyperglycemia-induced human umbilical vein endothelial cells (HUVECs). This study aimed to investigate the potential involvement of putative novel miR-1133 in oxidative stress in hyperglycemia-induced HUVECs. Methods: Functional enrichment and protein–protein interaction (PPI) network analyses were performed to identify biologically relevant predicted target genes of putative novel miR-1133. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) was selected for further investigation because it was identified as a hub gene in the PPI network and was involved in the enriched PI3K/Akt signaling pathway. HUVECs were exposed to high glucose (33.3 mM) to establish an in vitro hyperglycemic model, and the effects of transfection with putative novel miR-1133 inhibitor on PIK3CA expression and oxidative stress markers were evaluated. Results: Bioinformatic analyses identified PIK3CA as a hub gene among the predicted targets of putative novel miR-1133 and identified the PI3K/Akt signaling pathway as significantly enriched. Experimentally, hyperglycemia significantly reduced PIK3CA expression, whereas putative novel miR-1133 inhibitor transfection increased PIK3CA expression. Furthermore, putative novel miR-1133 inhibitor transfection was associated with reduced reactive oxygen species and 8-hydroxy-2′-deoxyguanosine levels, together with increased superoxide dismutase 1 (SOD1) mRNA expression and total SOD activity. Conclusions: Transfection with putative novel miR-1133 inhibitor was associated with increased PIK3CA expression and reduced oxidative stress markers in hyperglycemia-induced endothelial cells. Together, bioinformatic and experimental findings support an association between putative novel miR-1133 inhibitor transfection, PIK3CA expression, and oxidative stress under hyperglycemic conditions. Further studies are required to validate the direct interaction between putative novel miR-1133 and PIK3CA and to determine the relevance of these findings in vivo.