Fluoxetine up-regulates expression of cellular FLICE-inhibitory protein and inhibits LPS-induced apoptosis in hippocampus-derived neural stem cell

Fluoxetine is a widely used antidepressant compound which inhibits the reuptake of serotonin in the central nervous system. Recent studies have shown that fluoxetine can promote neurogenesis and improve the survival rate of neurons. However, whether fluoxetine modulates the proliferation or neuroprotection effects of neural stem cells (NSCs) needs to be elucidated. In this study, we demonstrated that 20 microM fluoxetine can increase the cell proliferation of NSCs derived from the hippocampus of adult rats by MTT test. The up-regulated expression of Bcl-2, Bcl-xL and the cellular FLICE-inhibitory protein (c-FLIP) in fluoxetine-treated NSCs was detected by real-time RT-PCR. Our results further showed that fluoxetine protects the lipopolysaccharide-induced apoptosis in NSCs, in part, by activating the expression of c-FLIP. Moreover, c-FLIP induction by fluoxetine requires the activation of the c-FLIP promoter region spanning nucleotides -414 to -133, including CREB and SP1 sites. This effect appeared to involve the phosphatidylinositol-3-kinase-dependent pathway. Furthermore, fluoxetine treatment significantly inhibited the induction of proinflammatory factor IL-1beta, IL-6, and TNF-alpha in the culture medium of LPS-treated NSCs (p<0.01). The results of high performance liquid chromatography coupled to electrochemical detection further confirmed that fluoxentine increased the functional production of serotonin in NSCs. Together, these data demonstrate the specific activation of c-FLIP by fluoxetine and indicate the novel role of fluoxetine for neuroprotection in the treatment of depression.     

Identification of CD133-positive radioresistant cells in atypical teratoid/rhabdoid tumor

Atypical teratoid/rhabdoid tumor (AT/RT) is an extremely malignant neoplasm in the central nervous system (CNS) which occurs in infancy and childhood. Recent studies suggested that CD133 could be considered a marker for brain cancer stem-like cells (CSCs). However, the role of CD133 in AT/RT has never been investigated. Herein we report the isolation of CD133-positive cells (CD133(+)), found to have the potential to differentiate into three germ layer tissues, from tissues of nine AT/RT patients. The migration/invasion/malignancy and radioresistant capabilities of CD133(+) were significantly augmented when compared to CD133(-). The clinical data showed that the amount of CD133(+) in AT/RTs correlated positively with the degree of resistance to radiation therapy. Using cDNA microarray analysis, the genotoxic-response profiles of CD133(+) and CD133(-) irradiated with 10 Gy ionizing radiation (IR) were analyzed 0.5, 2, 6, 12 and 24 h post-IR. We then validated these microarray data and showed increased phosphorylation after IR of p-ATM, p-RAD17, and p-CHX2 as well as increased expression of BCL-2 protein in CD133(+) compared to CD133(-). Furthermore, we found that CD133(+) can effectively resist IR with cisplatin- and/or TRAIL-induced apoptosis. Immunohistochemical analysis confirmed the up-regulated expression of p-ATM and BCL-2 proteins in IR-treated CD133(+) xenotransgrafts in SCID mice but not in IR-treated CD133(-). Importantly, the effect of IR in CD133(+) transplanted mice can be significantly improved by a combination of BCL-2 siRNA with debromohymenialdisine, an inhibitor of checkpoint kinases. In sum, this is the first report indicating that CD133(+) AT/RT cells demonstrate the characteristics of CSCs. The IR-resistant and anti-apoptotic properties in CD133(+) may reflect the clinical refractory malignancy of AT/RTs and thus the activated p-ATM pathway and BCL-2 expression in CD133(+) could be possible targets to improve future treatment of deadly diseases like AT/RT.     

Aldehyde dehydrogenase 1 is a putative marker for cancer stem cells in head and neck squamous cancer

Aldehyde dehydrogenase 1 (ALDH1) has been considered to be a marker for cancer stem cells. However, the role of ALDH1 in head and neck squamous cell carcinoma (HNSCC) has yet to be determined. In this study, we isolated ALDH1-positive cells from HNSCC patients and showed that these HNSCC-ALDH1⁺ cells displayed radioresistance and represented a reservoir for generating tumors. Based on microarray findings, the results of Western blotting and immunofluorescent assays further confirmed that ALDH1⁺-lineage cells showed evidence of having epithelial-mesenchymal transition (EMT) shifting and endogenously co-expressed Snail. Furthermore, the knockdown of Snail expression significantly decreased the expression of ALDH1, inhibited cancer stem-like properties, and blocked the tumorigenic abilities of CD44⁺CD24⁻ALDH1⁺ cells. Finally, in a xenotransplanted tumorigenicity study, we confirmed that the treatment effect of chemoradiotherapy for ALDH1⁺ could be improved by Snail siRNA. In summary, it is likely that ALDH1 is a specific marker for the cancer stem-like cells of HNSCC.     

A novel in vitro retinal differentiation model by co-culturing adult human bone marrow stem cells with retinal pigmented epithelium cells

Human retinal pigment epithelium (HRPE) cells are important in maintaining the normal physiology within the neurosensory retina and photoreceptors. Recently, transplantation of HRPE has become a possible therapeutic approach for retinal degeneration. By negative immunoselection (CD45 and glycophorin A), in this study, we have isolated and cultivated adult human bone marrow stem cells (BMSCs) with multilineage differentiation potential. After a 2- to 4-week culture under chondrogenic, osteogenic, adipogenic, and hepatogenic induction medium, these BMSCs were found to differentiate into cartilage, bone, adipocyte, and hepatocyte-like cells, respectively. We also showed that these BMSCs could differentiate into neural precursor cells (nestin-positive) and mature neurons (MAP-2 and Tuj1-positive) following treatment of neural selection and induction medium for 1 month. Furthermore, the plasticity of BMSCs was confirmed by initiating their differentiation into retinal cells and photoreceptor lineages by co-culturing with HRPE cells. The latter system provides an ex vivo expansion model of culturing photoreceptors for the treatment of retinal degeneration diseases.     

Estradiol Secretion by Tadpole Ovaries Masculinized by Implanted Capsules of Cyanoketone

Female tadpoles of Rana catesbeiana were laparotomized at metamorphic stages XI-XIII and an empty capsule or one containing cyanoketone (CK), which is an inhibitor of Δ⁵-3β-hydroxysteroid dehydrogenase (Δ⁵-3β-HSD), was implanted intraperitoneally. Ovarian activity of Δ⁵-3β-HSD was examined histochemically 2 months later, estradiol-17β (E₂) secretion by the ovaries was measured by RIA 4 months later and histological changes of the ovaries were examined 6 months later. The Δ⁵-3β-HSD activity of the CK-treated ovaries was much lower than that of controls. E₂ secretion per froglet by CK-treated ovaries was about one third that of controls (p<0.001). Histological examination showed various degrees of masculinization of the ovaries, about 28% of which were totally transformed into testis-like structures.
As a result of suppressed Δ⁵-3β-HSD activity, dehydroepiandrosterone would have accumulated, resulting in deficient E₂ secretion and, therefore, ovarian masculinization. In tadpoles, this effect does not depend on the pituitary, whereas interrenal hyperplasia and hyperactivity do, indicating that interrenal function is not essential for ovarian masculinization. From these findings and our previous results, we suggest that disturbance of steroidogenesis by CK in the ovaries results in their masculinization.     

Placenta-derived multipotent stem cells induced to differentiate into insulin-positive cells

In the present study, we successfully isolated PDMSCs from human placental tissues. The RT-PCR results show that PDMSCs preserved the genetic characteristics of the primitive embryonic stage--Oct-4 and Nanog. By using serum-free medium supplemented essential growth factors and induction medium culture for 4 weeks, a monolayer of spindle-like PDMSCs gradually formed 3D spheroid bodies (SB-PDMSCs). By using real-time RT-PCR, early mRNA expressions of Pdx1, as well as the Sox17 and Foxa2 genes, were observed to be significantly activated in SB-PDMSCs, followed by the expression of mature pancreas-related genes (insulin, glucagon, and somatostatin). The high insulin content of SB-PDMSCs was further confirmed by ELISA assay, and the glucose dependency was demonstrated by the corresponding insulin secretion level. In a transplantation study of streptozotocin-pretreated nude mice, the restoration of normoglycemia in the SB-PDMSC treated group was further observed. In conclusion, these results indicate that PDMSCs are an excellent source for the induced differentiation of well-functioning insulin-positive cells. The potential of these insulin producing cells derived from PDMSCs was also demonstrated functionally by the demonstration of secreted insulin in vitro and effective control of blood glucose levels in vivo.     

Salvianolic acid B attenuates MMP-2 and MMP-9 expression in vivo in apolipoprotein-E-deficient mouse aorta and in vitro in LPS-treated human aortic smooth muscle cells

Salvianolic acid B (Sal B), a water-soluble antioxidant derived from a Chinese medicinal herb, is believed to have multiple therapeutic and preventive against human vascular diseases, including atherosclerosis and restenosis. To elucidate the underlying cellular mechanisms, we produced hypercholesterolemia by feeding apo-E-deficient mice a 0.15% cholesterol diet and inflammation in human aortic smooth muscle cells (HASMCs) with the endotoxin lipopolysaccharide (LPS), focusing on the metallopreteinases MMP-2 and MMP-9, the relevant signal transduction pathways and the effects of Sal B. Immunohistochemical analyses indicated apo-E-deficient mice fed a 0.15% cholesterol diet for 12 weeks exhibited thickened intima and elevated levels of MMP-2 and MMP-9 in aortic sections, both of which were attenuated by 0.3% Sal B dietary supplement. Western blotting and zymography analyses indicated that unstimulated HASMCs exhibited basal levels of protein and activity levels for MMP-2 and barely detectable levels for MMP-9, both of which were markedly upregulated by LPS, which also induced cell migration. Sal B significantly attenuated upregulations of both MMPs as well as the LPS-induced cell migration through the inactivation of MMP-2 and MMP-9 protein synthesis as well as the downregulation of the extracellular-signal-regulated kinase 1/2 (ERK1/2) and c-Jun NH(2)-terminal kinase (JNK). These results demonstrate that Sal B has anti-migration properties on smooth muscle cells and may explain its anti-atherosclerotic properties. This novel mechanism of action of Sal B, in addition to its previously reported inhibition of LDL oxidation, may help explain its efficacy in the treatment of atherosclerosis.     

The immediate early 2 protein of human cytomegalovirus (HCMV) mediates the apoptotic control in HCMV retinitis through up-regulation of the cellular FLICE-inhibitory protein expression

Human CMV (HCMV) is a widespread human pathogen that causes blindness by inducing retinitis in AIDS patients. Previously, we showed that viral immediate early 2 (IE2) protein may allow HCMV to evade the immune control by killing the Fas receptor-positive T lymphocytes attracted to the infected retina with increased secretion of Fas ligand (FasL). In this study, we further demonstrate that the secreted FasL also kills uninfected Fas-rich bystander retinal cells and that IE2 simultaneously protects the infected cells from undergoing apoptotic death, in part, by activating the expression of cellular FLIP (c-FLIP), an antiapoptotic molecule that blocks the direct downstream executer caspase 8 of the FasL/Fas pathway. c-FLIP induction requires the N-terminal 98 residues of IE2 and the c-FLIP promoter region spanning nucleotides -978 to -696. In vivo association of IE2 to this region, IE2-specific c-FLIP activation, and decrease of FasL-up-regulated activities of caspases 8 and 3 were all demonstrated in HCMV-infected human retinal cells. Moreover, c-FLIP up-regulation by IE2 appeared to involve PI3K and might also render cells resistant to TRAIL-mediated death. Finally, enhanced c-FLIP signals were immunohistochemically detected in IE-positive cells in the HCMV-infected lesions of the human retina. Taken together, these data demonstrate specific activation of c-FLIP by HCMV IE2 and indicate a novel role for c-FLIP in the pathogenesis of HCMV retinitis.