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Patients with diabetes mellitus have a higher risk of developing Parkinson's disease (PD). However, the molecular links between PD and diabetes remain unclear. In this study, we investigated the roles of thioredoxin-interacting protein (TXNIP) in Parkin/PINK1-mediated mitophagy in dopaminergic (DA) cells under high-glucose (HG) conditions. In streptozotocin-induced diabetic mice, TXNIP was upregulated and autophagy was inhibited in the midbrain, while the loss of DA neurons was accelerated by hyperglycemia. In cultured PC12 cells under HG, TXNIP expression was upregulated and the intracellular reactive oxygen species (ROS) levels increased, leading to cell death. Autophagic flux was further blocked and PINK1 expression was decreased under HG conditions. Parkin expression in the mitochondrial fraction and carbonyl cyanide 3-chlorophenylhydrazone (CCCP)-induced co-localization of COX IV (marker for mitochondria) and LAMP1 (marker for lysosomes) were also significantly decreased by HG. Overexpression of TXNIP was sufficient to decrease the expression of both PINK1 and Parkin in PC12 cells, while knockdown of the expression of TXNIP by siRNA decreased intracellular ROS and attenuated cellular injury under HG. Moreover, inhibition of TXNIP improved the CCCP-induced co-localization of COX IV and LAMP1 in PC12 cells under HG. Together, these results suggest that TXNIP regulates Parkin/PINK1-mediated mitophagy under HG conditions, and targeting TXNIP may be a promising therapeutic strategy for reducing the risk of PD under hyperglycemic conditions.

Background: MicroRNAs (miRNAs) are involved in the initiation and development of cancer, and participate in drug resistance. Paclitaxel (PTX) is first-line chemotherapy drug for advanced non-small cell lung cancer (NSCLC). The abnormal miRNA expression in NSCLC and its association with chemotherapy drug resistance remains largely unknown. The study aimed to investigate the aberrant expression of miR-221-3p in NSCLC and to elucidate its molecular mechanisms in relation to PTX resistance.Methods: Quantitative polymerase chain reaction (qPCR) was used to examine miRNA and messenger RNA (mRNA) in NSCLC tissues and cell lines. The roles of miR-221-3p in NSCLC progression and drug resistance were assessed by Western blot analysis, colony formation assay, and CCK-8. Dual-luciferase reporter assay was conducted to evaluate the interaction between miR-221-3p and MDM2. Xenograft tumor models were established by subcutaneously injecting PTX-resistant A549 cells (A549/Taxol) to assess the effect of miR-221-3p on tumor growth. Data regarding miRNAs and target proteins from 20 NSCLC tissues and paired non-cancerous matched tissues were also obtained for correlation analysis. Results: PTX increased miR-221-3p expression, which regulated MDM2/P53 expression in the PTX-sensitive NSCLC strain (A549). Meanwhile, miR-221-3p was rarely expressed and not interfered by PTX in A549/Taxol. Dual luciferase reporter assay confirmed that miR-221-3p specifically binds to MDM2 mRNA. MiR-221-3p down-regulation reduced the sensitivity of A549 cells to PTX, whereas its up-regulation partially reversed the A549/Taxol cells resistance to PTX and increased the chemosensitivity of A549/Taxol cells to PTX in xenograft models. QPCR analysis revealed that miR-221-3p expression increased, whereas the MDM2 level decreased in NSCLC tumor tissues. Furthermore, the result of Western bolt analysis showed that P53 was lowly expressed in tumor tissues with MDM2 overexpression.Conclusions: MiR-221-3p overexpression could regulate MDM2/p53 signaling pathway to reverse the PTX resistance of NSCLC and induce apoptosis in vitro and vivo.

Background This study aimed to investigate the aberrant expression of hsa_circ_0002874 in non-small cell lung cancer (NSCLC) and elucidate associated molecular mechanisms that influence apoptosis and induce paclitaxel (PTX) resistance. Methods Inhibitors were used to downregulate circRNA or miRNA expression. pCDNA plasmid transfection and mimics were used to upregulate circRNA or miRNA expression. Dual-luciferase reporter assays were conducted to evaluate interactions between miR1273f and MDM2. Xenograft tumor models were used to assess the effect of hsa_circ_0002874 and miR1273f on tumor growth. NSCLC tissues and matched non-cancerous tissues were also collected for correlation analysis. Results hsa_circ_0002874 acts as a sponge for miR1273f which targets MDM2/P53. The stability of the hsa_circ_0002874/miR1273f/MDM2/P53 pathway was verified by upregulating and downregulating the expression of hsa_circ_0002874 and miR1273f. hsa_circ_0002874 downregulation or miR1273f upregulation reversed the resistance of the A549/Taxol cells in xenograft models. The expression of hsa_circ_0002874 was high, and the level of MDM2 was low in NSCLC tissues. P53 was only weakly expressed in NSCLC tissues with high expression of MDM2. Conclusions hsa_circ_0002874 is strongly expressed in NSCLC tissues and maybe a potential marker for PTX resistance. hsa_circ_0002874 downregulation could regulate miR1273f/MDM2/P53 signaling pathway to reverse the PTX resistance of NSCLC and induce apoptosis in vitro and vivo.

Paclitaxel (PTX) is a first-line chemotherapy drug for advanced non-small cell lung cancer (NSCLC). The long-chain non-coding RNA maternally expressed gene 3 (MEG3) is a recognized tumor suppressor. This study aimed to explore the effects of PTX on the expression of MEG3 and its anti-tumor mechanism in lung cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were performed to determine cell proliferation. Quantitative polymerase chain reaction was used to determine the levels of MEG3 expressions. Western blot and immunofluorescence were used to detect protein levels. Small interfering RNA or pCDNA-MEG3 transfection was used to downregulate or upregulate MEG3 expression. Dichlorof luorescein diacetate was used to detect intracellular reactive oxygen species. Flow cytometry was used to analyze apoptosis. PTX significantly inhibited the proliferation of NSCLC cells and increased the expressions of MEG3 and P53. The downregulation of MEG3 attenuated PTX-induced cytotoxicity, whereas upregulation of MEG3 induced cell death and increased P53 expression. The inhibition of P53 caused no effect on the upstream MEG3 expression. Our results suggest that the MEG3-P53 pathway is involved in the apoptosis of A549 cells induced by PTX.