Ceramide is an important lipid messenger involved in mediating a variety of cell functions including apoptosis. However, mechanisms responsible for ceramide-induced apoptosis remain unclear. We investigated the possibility that ceramide may decrease antiapoptotic signaling in cells by inhibiting Akt kinase activity. Our data show that C2-ceramide induces apoptosis in HMN1 motor neuron cells and decreases both basal and insulin- or serum-stimulated Akt kinase activity 65–70%. These results are consistent with decreased Akt kinase activity being involved in the apoptotic effects of ceramide. This possibility is further supported by studies showing that constitutively active Akt kinase decreases C2-ceramide-induced death of HMN1 cells as well as COS-7 cells. Decreased Akt activity is not due to ceramide activating the ceramide-activated protein phosphatase or to a direct inhibition of Akt kinase by ceramide, suggesting that ceramide acts upstream of Akt kinase to decrease its activity. Treating cells with C2-ceramide does not affect phosphorylation of insulin receptor substrate-1, interactions between insulin receptor substrate-1 and p85, or insulin-stimulated phosphatidylinositol 3-kinase activity, suggesting that the effects of C2-ceramide on Akt kinase are not mediated through modulating phosphatidylinositol 3-kinase. In sum, our results suggest that inhibition of the key antiapoptotic kinase, Akt, may play an important role in ceramide-induced apoptosis.
Liver fibrosis remains a serious problem affecting the health of millions of people worldwide. Hepatic stellate cells (HSCs) are the main effector cells in liver fibrosis and their activation could lead to extracellular matrix deposition, which may aggravate the development of liver fibrosis and inflammation. Previous studies have reported the potential of Phillygenin (PHI) as a hepatoprotective agent to inhibit HSCs activation and fibrosis development. However, the poor water solubility of PHI hinders its clinical application as a potential anti-liver fibrosis therapy. Milk-derived exosomes (mEXO) serve as scalable nanocarriers for delivering chemotherapeutic agents due to their excellent biocompatibility. Here, we developed a PHI-Hyaluronic acid (HA) composite mEXO (PHI-HA-mEXO) drug delivery system, in which DSPE-PEG2000-HA was conjugated to the surface of mEXO to prepare HA-mEXO, and PHI was encapsulated into HA-mEXO to form PHI-HA-mEXO. As a specific receptor for HA, CD44 is frequently over-expressed during liver fibrosis and highly expressed on the surface of activated HSCs (aHSCs). PHI-HA-mEXO can bind to CD44 and enter aHSCs through endocytosis and release PHI. PHI-HA-mEXO drug delivery system can significantly induce aHSCs death without affecting quiescent HSCs (qHSCs) and hepatocytes. Furthermore, we carried out in vitro and in vivo experiments and found that PHI-HA-mEXO could alleviate liver fibrosis through aHSCs-targeted mechanism. In conclusion, the favorable biosafety and superior anti-hepatic fibrosis effects suggest a promising potential of PHI-HA-mEXO in the treatment of hepatic fibrosis. However, detailed pharmokinetics and dose-responsive experiments of PHI-HA-mEXO and the mechanism of mEXO loading drugs are still required before PHI-HA-mEXO can be applied clinically.
The sphingomyelin derivative ceramide is a signaling molecule implicated in numerous physiological events.Recently published reports indicate that ceramide levels are elevated in insulin-responsive tissues of diabetic animals and that agents which trigger ceramide production inhibit insulin signaling.In the present series of studies, the short-chain ceramide analog C 2 -ceramide inhibited insulin-stimulated glucose transport by ϳ50% in 3T3-L1 adipocytes, with similar reductions in hormone-stimulated translocation of the insulin-responsive glucose transporter (GLUT4) and insulin-responsive aminopeptidase.C 2 -ceramide also inhibited phosphorylation and activation of Akt, a molecule proposed to mediate multiple insulin-stimulated metabolic events.C 2 -ceramide, at concentrations which antagonized activation of both glucose uptake and Akt, had no effect on the tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) or the amounts of p85 protein and phosphatidylinositol kinase activity that immunoprecipitated with anti-IRS-1 or antiphosphotyrosine antibodies.Moreover, C 2 -ceramide also inhibited stimulation of Akt by platelet-derived growth factor, an event that is IRS-1 independent.C 2 -ceramide did not inhibit insulin-stimulated phosphorylation of mitogen-activated protein kinase or pp70 S6-kinase, and it actually stimulated phosphorylation of the latter in the absence of insulin.Various pharmacological agents, including the immunosuppressant rapamycin, the protein synthesis inhibitor cycloheximide, and several protein kinase C inhibitors, were without effect on ceramide's inhibition of Akt.These studies demonstrate ceramide's capacity to inhibit activation of Akt and imply that this is a mechanism of antagonism of insulin-dependent physiological events, such as the peripheral activation of glucose transport and the suppression of apoptosis.
Using Southern hybridization, we analysed the telomere length from thirty patients with nasopharyngeal carcinoma and demonstrated telomere reduction in these individuals when compared with their age-matched controls. Of the 30 samples, 16.67% had telomere elongation, 76.67% had telomere reduction and 6.67% exhibited equal lengths as compared with the controls. Analysis of leukocytes from 30 controls indicated that the telomere length decreased (average 39 base Pairs Per year) with aging and a statistically significant correlation between the length and age was noted (r = -0.3913, P < 0.05). These results suggest that the consequences of telomere shortening in nasopharyngeal carcinoma may lead to chromosome instability.
Ovarian cancer is one of the most common human malignancies in women. MiR-214 and semaphorin 4D (sema 4D) were found to be abhorrently expressed and involved in the progress of several kinds of malignant cancers. This study is aimed to investigate the cellular role of miR-214 and demonstrate that miR-214 negatively regulated sema 4D in ovarian cancer cells. The data showed that miR-214 expression was consistently lower in ovarian cancer tissues and cells than those in the normal controls. Over-expression of miR-214 in ovarian cancer SKOV-3 cells inhibited cell proliferation and induced apoptosis. It was suggested that miR-214 functioned as the tumor suppressor in ovarian cancer. Bioinformatic analysis indicated that miR-214 possibly regulated sema 4D by binding the sema 4D messenger RNA (mRNA) 3'-untranslated region (UTR). Sema 4D mRNA and protein levels were up-regulated in ovarian cancer tissues and SKOV-3 cells. Up-regulation of miR-214 in SKOV-3 cell line suppressed the sema 4D expression in both protein and nucleic acid levels. While, down-regulation of miR-214 in SKOV-3 cells would increase sema 4D protein and nucleic acid expression levels. The effects of miR-214 up- and down-regulation on luciferase activities of wild-type (WT) sema 4D 3'-UTR were completely removed upon introduction of mutation in 3'-UTR of WT sema 4D. Therefore, the data also demonstrated that sema 4D was the direct target of miR-214 and was negatively regulated by miR-214 in ovarian cancer cells.
Abstract This study aimed to examine hTERC gene in different grades of cervical intraepithelial neoplasia (CIN) and cervical cancer, and the association between hTERC and high risk-human papillomavirus (HR-HPV) infection. Patients who underwent cervical cancer screening at the Second Affiliated Hospital of Kunming Medical University between October 2010 and December 2011 were enrolled. All patients underwent liquid-based cytology test and hybrid capture 2 (HC2) for HPV detection. hTERC was examined using fluorescence in situ hybridization (FISH). Cervical colposcopy biopsy was performed if any of the three results was positive. HC2, FISH, and pathology were compared. A total of 1200 women underwent screening, 150 patients underwent cervical biopsy: 32 in the normal group, 38 in the CIN1 group, 66 in the CIN2/3 group, and 14 in the invasive cervical cancer group. More patients had HR-HPV infection in the CIN2/3 group and ICC group compared with the CIN1 group. hTERC increased with increasing histological dysplasia. There was significant difference in hTERC positive rate between each of the three groups. More patients with hTERC gene amplification were observed in the positive HR-HPV group than in the HR-HPV negative group. In conclusion, hTERC is a potential marker for precancerous cervical cancer lesions. hTERC might be correlated with HR-HPV infection in cervical diseases.
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