Explore the vast range of titles available.

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by suppressing the target mRNA and inhibiting translation in order to regulate multiple biological processes. miRNAs play important roles as oncogenes or tumor suppressors in the development of various types of human cancer. The regulation of mammalian target of rapamycin (mTOR) by miRNAs has been studied in several types of cancer, including colorectal cancer (CRC). However, to the best of our knowledge, only limited information regarding the function of miRNAs in human CRC is available. In the present study, the expression of 22 miRNAs in CRC cell lines were investigated in regard to key genes in the mTOR pathway. Initially, it was revealed that mTOR, regulatory-associated protein of mTOR complex I and rapamycin-intensive companion of mTOR were overexpressed in CRC cell lines when compared with a normal colorectal cell line. Subsequently, putative miRNA-mRNA associations were identified via multiple miRNA target prediction programs. The expression levels for the candidate miRNAs were validated using quantitative real-time polymerase chain reaction. Expression analysis revealed that, among 20 miRNAs, five miRNAs (miR-496, miR-1185, miR-654, miR-3183 and miR-495) exhibited significant downregulation in association with the mTOR signaling pathway. Taken together, the results from the present study suggest that several miRNAs that are associated with CRC, with possible roles in mTOR signaling, may have potential therapeutic or diagnostic benefits in CRC treatment.

Rapamycin treatment has been shown to increase autophagy activity and activate Akt phosphorylation, suppressing apoptosis in several models of ischemia reperfusion injury. However, little has been studied on the neuroprotective effects on spinal cord injury by activating Akt phosphorylation. We hypothesized that both effects of rapamycin, the increased autophagy activity and Akt signaling, would contribute to its neuroprotective properties. In this study, a compressive spinal cord injury model of rat was created by an aneurysm clip with a 30 g closing force. Rat models were intraperitoneally injected with rapamycin 1 mg/kg, followed by autophagy inhibitor 3-methyladenine 2.5 mg/kg and Akt inhibitor IV 1 µg/kg. Western blot assay, immunofluorescence staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay were used to observe the expression of neuronal autophagy molecule Beclin 1, apoptosis-related molecules Bcl-2, Bax, cytochrome c, caspase-3 and Akt signaling. Our results demonstrated that rapamycin inhibited the expression of mTOR in injured spinal cord tissue and up-regulated the expression of Beclin 1 and phosphorylated-Akt. Rapamycin prevented the decrease of bcl-2 expression in injured spinal cord tissue, reduced Bax, cytochrome c and caspase-3 expression levels and reduced the number of apoptotic neurons in injured spinal cord tissue 24 hours after spinal cord injury. 3-Methyladenine and Akt inhibitor IV intervention suppressed the expression of Beclin-1 and phosphorylated-Akt in injured spinal cord tissue and reduced the protective effect of rapamycin on apoptotic neurons. The above results indicate that the neuroprotective effect of rapamycin on spinal cord injury rats can be achieved by activating autophagy and the Akt signaling pathway.

It has been reported that ginsenoside Rg1 (G-Rg1) can alleviate alcoholic liver injury, cardiac hypertrophy and myocardial ischemia, as well as reperfusion injury. Therefore, the present study aimed to investigate the role of G-Rg1 in alcohol-induced myocardial injury, as well as to elucidate its underlying mechanisms of action. For this purpose, H9c2 cells were stimulated with ethanol. Subsequently, H9c2 cell viability and apoptosis were determined using a Cell Counting Kit-8 assay and flow cytometric analysis, respectively. The levels of lactate dehydrogenase and caspase-3 in the H9c2 cell culture supernatant were detected using corresponding assay kits. In addition, the expression of green fluorescent protein (GFP)-light chain 3 (LC3) and that of C/EBP homologous protein (CHOP) were evaluated using GFP-LC3 assay and immunofluorescence staining, respectively. The expression levels of apoptosis-, autophagy-, endoplasmic reticulum stress (ERS)- and adenosine 5′-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway-related proteins were detected using western blot analysis. The results revealed that treatment with G-Rg1 enhanced the viability and suppressed the apoptosis of ethanol-stimulated H9c2 cells. G-Rg1 also attenuated autophagy and ERS in ethanol-stimulated H9c2 cells. In addition, the levels of phosphorylated (p)-protein kinase R (PKR)-like ER kinase (PERK), p-eukaryotic translation initiation factor 2a, activating transcription factor 4 (ATF4), CHOP, caspase-12 and p-AMPK were downregulated, while the p-mTOR level was upregulated in ethanol-stimulated H9c2 cells treated with G-Rg1. Furthermore, the co-treatment of G-Rg1-treated ethanol-stimulated H9c2 cells with AICAR, an AMPK agonist, or CCT020312, a PERK agonist, inhibited cell viability and promoted cell apoptosis, autophagy and ERS. Overall, the results of the present study suggest that G-Rg1 suppresses autophagy and ERS via inhibiting the AMPK/mTOR and PERK/ATF4/CHOP pathways to alleviate ethanol-induced H9c2 cell injury.

Strontium (Sr) is an alkaline earth metal that exerts the dual effect of improving bone formation and suppressing bone resorption, resulting in increased bone apposition rates and bone mineral density. However, the mechanisms through which Sr exerts these beneficial effects on bone have yet to be fully elucidated. The present study aimed to reveal the underlying molecular mechanisms associated with Sr-induced osteogenic differentiation. The effects of Sr on cell proliferation and osteogenic differentiation were analyzed by MTT assay, RT-qPCR, western blot analysis, alkaline phosphatase (ALP) and Alizarin red staining assays. The extent of autophagy was determined by monodansylca-daverine (MDC) staining and western blot analysis of two markers of cellular autophagic activity, the steatosis-associated protein, sequestosome-1 (SQSTM1/p62), and the two isoforms of microtubule-associated protein 1 light chain 3 (LC3), LC-3-I/II. The expression levels of AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were also detected by western blot analysis. Sr at a concentration of 3 mM exerted the most pronounced effect on osteogenic differentiation, without any apparent cell toxicity. At the same time, cellular autophagy was active during this process. Subsequently, autophagy was blocked by 3-methyl-adenine, and the enhancement of osteogenic differentiation in response to Sr was abrogated. Additionally, the phosphorylation level of AMPK was significantly increased, whereas that of mTOR was significantly decreased, in the Sr-treated group. Taken together, the findings of the present study demonstrate that Sr stimulates AMPK-activated autophagy to induce the osteogenic differentiation of MC3T3-E1 cells.

Intracellular signaling pathways, including the mammalian target of rapamycin (mTOR) and the mitogen-activated protein kinase (MAPK) pathway, are activated by exercise, and promote skeletal muscle hypertrophy. However, the mechanisms by which these pathways are activated by physiological stimulation are not fully understood. Here we show that extracellular ATP activates these pathways by increasing intracellular Ca2+ levels ([Ca2+]i), and promotes muscle hypertrophy. [Ca2+]i in skeletal muscle was transiently increased after exercise. Treatment with ATP induced the increase in [Ca2+]i through the P2Y2 receptor/inositol 1,4,5-trisphosphate receptor pathway, and subsequent activation of mTOR in vitro. In addition, the ATP-induced increase in [Ca2+]i coordinately activated Erk1/2, p38 MAPK and mTOR that upregulated translation of JunB and interleukin-6. ATP also induced an increase in [Ca2+]i in isolated soleus muscle fibers, but not in extensor digitorum longus muscle fibers. Furthermore, administration of ATP led to muscle hypertrophy in an mTOR- and Ca2+-dependent manner in soleus, but not in plantaris muscle, suggesting that ATP specifically regulated [Ca2+]i in slow muscles. These findings suggest that ATP and [Ca2+]i are important mediators that convert mechanical stimulation into the activation of intracellular signaling pathways, and point to the P2Y receptor as a therapeutic target for treating muscle atrophy.

Panax notoginseng saponins (PNS) are active extracts obtained from the P. notoginseng plant. PNS exhibit various anti-inflammatory, anti-oxidant and anti-aging pharmacological properties in some cells. However, the effects of PNS on senescence and apoptosis in chondrocytes have not been studied to date. In the present study, whether PNS could limit tumor necrosis factor (TNF)-α-induced senescence and apoptosis in chondrocytes and whether they could slow down cartilage degeneration in a surgery-induced rat osteoarthritis (OA) model by regulating the phosphatidyl inositol 3 kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) signaling pathway was examined. A potential mechanism underlying these effects was further elucidated. The present in vitro experiments showed that PNS significantly inhibited senescence and apoptosis in OA chondrocytes and prevented a decrease in the mitochondrial membrane potential and excessive mitochondrial permeability. In addition, the expression levels of autophagy-related proteins and the anti-apoptotic protein Bcl-2 were significantly increased in PNS-treated OA chondrocytes, but the expression levels of Bax and caspase-3 were decreased; these effects were concentration-dependent. TNF-α significantly increased the expression of p-PI3K/p-AKT/p-mTOR in OA chondrocytes, whereas PNS reduced PI3K, AKT and mTOR phosphorylation. The results of the in vivo experiments demonstrated that PNS significantly inhibited the PI3K-AKT-mTOR signaling pathway and collagen II degradation, as well as reduced matrix metalloproteinase (MMP)-3 and MMP-13 expression in chondrocytes in a rat OA model, thus attenuating cartilage destruction in OA. The results obtained in the rat model were consistent with the in vitro experimental results. Furthermore, histological analyses and ultrastructural observations confirmed these results. Taken together, the results of the present study demonstrated that PNS may protect osteoarthritic chondrocytes from senescence and apoptosis by inhibiting the PI3K-AKT pathway, thus delaying the degradation of articular cartilage.

The aim of the present study was to investigate the significance of cell apoptosis, the phosphoinositide-3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) pathway, and the 5′ adenosine monophosphate-activated protein kinase (AMPK)-mTOR pathways in the process of diabetic gastroparesis. Changes in gastric smooth muscle cells of diabetic rats with induced gastroparesis were examined. The diabetic rat model was established by dividing animals into a normal control group and diabetic model groups examined at 2, 4 and 6 weeks. Diabetic gastroparesis was evaluated by examining the rates of gastric residual pigment, whereas flow cytometry was used to detect the apoptosis of gastric smooth muscle cells. The expression levels of PI3K and phosphorylated (p-) AKT, AMPK, mTOR, tuberous sclerosis complex 2, p70 ribosomal S6 kinase, and eukaryotic translation initiation factor 4-binding protein 1 were determined in gastric muscles using western blot analysis. Diabetic gastroparesis was confirmed in models at 6 weeks. The apoptosis of gastric smooth muscle cells gradually increased in all diabetic groups, and significant changes were observed in key proteins involved in PI3K-AKT-mTOR and AMPK-mTOR signaling. The results indicated that apoptosis was important in the occurrence of diabetic gastroparesis, and the PI3K-AKT-mTOR and AMPK-mTOR pathways were activated during the apoptotic processes, but were incapable of regulating apoptosis.

Cisplatin is a common chemotherapeutic agent against ovarian cancer; however, drug resistance is a major limiting factor for its use in clinical treatment. The underlying mechanisms of cisplatin resistance in ovarian cancer have not yet been fully elucidated. Thus, this study aimed to elucidate some of the mechanisms responsible for resistance to cisplatin in ovarian cancer. The results demonstrated that the cisplatin-resistant human ovarian cancer cell lines, SKOV3/DDP and A2780/DDP, exhibited higher autophagy levels than the control ovarian cancer cell lines, SKOV3 and A2780. Moreover, autophagy inhibition by 3-methyladenine or shRNA against autophagy-related gene (ATG)5 potentiated the cytotoxicity induced by cisplatin, whereas autophagy induction by rapamycin (Rapa) increased cell survival. Exposure to cisplatin induced an upregulation in the expression of thioredoxin-related protein of 14 kDa (TRP14). Furthermore, TRP14 knockdown or overexpression decreased or increased the autophagy response and cisplatin resistance, and this effect was reversed by treatment with Rapa or ATG5 knockdown. The findings of this study also suggested that TRP14 induced autophagy and chemoresistance via the 5′AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/p70S6K signaling pathway. Importantly, the data from a tissue array revealed a positive association between TRP14 and Beclin1 in human ovarian cancer and marginal tissues. These findings have identified, for the first time, to the best of our knowledge, that TRP14 induces autophagy and consequently cisplatin resistance in ovarian cancer cells via the AMPK/mTOR/p70S6K signaling pathway. This in turn renders TRP14 as a potential predictor or target in ovarian cancer therapy.

Capsaicin (8-methyl N-vanillyl-6 nonenamide) is a natural plant extract that has antitumor properties and induces apoptosis and autophagy in various types of malignancies, including hepatocellular carcinoma (HCC). Sorafenib is a multi-kinase inhibitor that improves the survival of patients with advanced HCC. In the present study, capsaicin and sorafenib were found to inhibit the growth of LM3, Hep3B and HuH7 cells. In addition, the combination of capsaicin and sorafenib exerted a synergistic inhibitory effect on HCC cell growth. In LM3 cells, capsaicin and sorafenib combination treatment achieved a markedly stronger induction of apoptosis by increasing caspase-3, Bax and poly(ADP-ribose) polymerase activity and inhibiting Bcl-2, and induction of autophagy by upregulating the levels of beclin-1 and LC3A/B II, enhancing P62 degradation. The combination of capsaicin and sorafenib also inhibited cell invasion and metastasis via upregulation of E-cadherin and downregulation of N-cadherin, vimentin, matrix metalloproteinase (MMP)2 and MMP9. Additional studies suggested an association between the abovementioned anticancer activities and inhibition of the epidermal growth factor receptor/phosphoinositide 3 kinase/Akt/mammalian target of rapamycin pathway. Taken together, these data confirm that capsaicin and sorafenib combination treatment inhibits the growth, invasion and metastasis of HCC cells and induces autophagy in a synergistic manner, supporting its potential as a therapeutic option for HCC.

A diffusely invasive nature is a major obstacle in treating a malignant brain tumor, “diffuse glioma”, which prevents neurooncologists from surgically removing the tumor cells even in combination with chemotherapy and radiation. Recently updated classification of diffuse gliomas based on distinct genetic and epigenetic features has culminated in a multilayered diagnostic approach to combine histologic phenotypes and molecular genotypes in an integrated diagnosis. However, it is still a work in progress to decipher how the genetic aberrations contribute to the aggressive nature of gliomas including their highly invasive capacity. Here we depict a set of recent discoveries involving molecular genetic determinants of the infiltrating nature of glioma cells, especially focusing on genetic mutations in receptor tyrosine kinase pathways and metabolic reprogramming downstream of common cancer mutations. The specific biology of glioma cell invasion provides an opportunity to explore the genotype-phenotype correlation in cancer and develop novel glioma-specific therapeutic strategies for this devastating disease.