High glucose activates ERK1/2 to stabilize AP1 and increase MMP9 expression in diabetic foot ulcers.

Increased matrix metalloproteinase 9 (MMP9) expression is involved in delayed wound healing in diabetic foot ulcers. We created skin wounds in normal SD rats and STZ-induced diabetic SD rats, then we found protein levels of activator protein-1 (AP1), a crucial transcription factor to increase MMP9 transcription, as well as MMP9 was up-regulated in epithelium of diabetic skin tissues. Then, we evaluated the mRNA and protein stability of AP1 subunits C-FOS/C-Jun in HaCaT cells after high glucose treatment. Results showed that high glucose could increase protein stability of C-FOS and C-Jun. Additionally, high glucose also activated extracellular signaling-related kinase 1/2 (ERK1/2). ERK1/2 inhibitor could rescue phosphorylation of C-FOS and C-Jun, increased protein stability of C-Jun, and increased MMP9 expressions. Thus, our study demonstrated that high glucose could activate ERK1/2 to stabilize AP1 and increase MMP9 expression in diabetic skin and HaCaT cells.

Advanced glycation end-products suppress autophagy by AMPK/mTOR signaling pathway to promote vascular calcification.

Vascular calcification is closely linked to patients in diabetes mellitus and chronic kidney disease. Advanced glycation end-products (AGEs) are associated with osteogenic differentiation of vascular smooth muscle cell (VSMC), vascular calcification, and autophagy that takes part in the process. However, the underlying mechanism of the effects of AGEs on the phenotypic transition and autophagy of VSMCs is not clearly understood. In this study, we cultured the rat VSMC line (A7R5) and thoracic aorta organ with bovine serum albumin (BSA) or AGEs (AGEs-BSA) and detected proteins expression by Western blotting or immunofluorescence. Autophagosome was observed by transmission electron microscopy (TEM). The mineralization and calcific nodules were identified by Alizarin Red S and Von Kossa staining. AGEs significantly downregulated p-AMPKα expression and upregulated p-mTOR expression and then increased the expression of osteoblastic differentiation, while suppressing autophagy in a time-dependent pattern. Pretreatment with autophagy activator rapamycin and AMPK activator AICAR both upregulated the autophagy level and downregulated the effects of AGEs on osteoblastic differentiation of VSMCs. Moreover, the result from rat thoracic aorta culture also confirmed that AGEs promote vascular calcification in a time-dependent manner. Thus, our study showed that AGEs quicken vascular calcification and suppress autophagy associated with AMPK/mTOR signaling pathway.

MicroRNA-17-92 Regulates Beta-Cell Restoration After Streptozotocin Treatment.

Objective: To clarify the role and mechanism of miR-17-92 cluster in islet beta-cell repair after streptozotocin intervention. Methods: Genetically engineered mice (miR-17-92ßKO) and control RIP-Cre mice were intraperitoneally injected with multiple low dose streptozotocin. Body weight, random blood glucose (RBG), fasting blood glucose, and intraperitoneal glucose tolerance test (IPGTT) were monitored regularly. Mice were sacrificed for histological analysis 8 weeks later. Morphological changes of pancreas islets, quantity, quality, apoptosis, and proliferation of beta-cells were measured. Islets from four groups were isolated. MiRNA and mRNA were extracted and quantified. Results:MiR-17-92ßKO mice showed dramatically elevated fasting blood glucose and impaired glucose tolerance after streptozotocin treatment in contrast to control mice, the reason of which is reduced beta-cell number and total mass resulting from reduced proliferation, enhanced apoptosis of beta-cells. Genes related to cell proliferation and insulin transcription repression were significantly elevated in miR-17-92ßKO mice treated with streptozotocin. Furthermore, genes involved in DNA biosynthesis and damage repair were dramatically increased in miR-17-92ßKO mice with streptozotocin treatment. Conclusion: Collectively, our results demonstrate that homozygous deletion of miR-17-92 cluster in mouse pancreatic beta-cells promotes the development of experimental diabetes, indicating that miR-17-92 cluster may be positively related to beta-cells restoration and adaptation after streptozotocin-induced damage.

Bone turnover markers and novel biomarkers in lung cancer bone metastases.

CONTEXT: Lung cancer still remains the leading cause of cancer-related mortality worldwide. Bone is one of preferred metastatic sites for lung cancer cells. So far, both accurate diagnosis and effective treatment of lung cancer bone metastases are difficult. OBJECTIVE: This review aimed to evaluate roles of bone turnover markers (BTMs), microRNAs (miRNAs), dickkopf1 (DKK1) and insulin like growth factor binding protein 3 (IGFBP-3) in lung cancer bone metastases. METHODS: We searched articles about these four biomarkers in lung cancer bone metastases mainly in PubMed. RESULT: The levels of bone specific alkaline phosphatase (BALP), cross-linked carboxy-terminal telopeptide of type-I collagen (ICTP) and N-terminal telopeptides of type-I collagen (NTX) were reported to be significantly increased in lung cancer patients with bone metastases. ALP, NTX and bone sialoprotein were thought to be associated with prognosis of lung cancer patients with bone metastases. MiRNA-335, miRNA-33a, miRNA-21, DKK1 and IGFBP-3 were revealed to be novel biomarkers in lung cancer bone metastases. DISCUSSION AND CONCLUSION: Current researches have revealed that BTMs, miRNAs, DKK1 and IGFBP-3 may be useful in diagnosis, prognosis evaluation or treatment of lung cancer bone metastases. More studies about these biomarkers in lung cancer bone metastases are needed.