Silencing of forkhead box protein O-1 (FOXO-1) enhances insulin-producing cell generation from adipose mesenchymal stem cells for diabetes therapy.

AIMS: Generation of mature ß-cells from MSCs has been a challenge in the field of stem cell therapy of diabetes. Adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark in regenerative medicine, and provide several advantages compared to other MSCs sources. Forkhead box protein O-1 (FOXO-1) is an important transcription factor for normal development of ß-cells, yet its over expression in ß-cells may cause glucose intolerance. In this study, we isolated, characterized Ad-MSCs from rat epididymal fat pads, differentiated these MSCs into insulin producing cells (IPCs) and studied the role of FOXO-1 in such differentiation. MATERIALS AND METHODS: We examined the expression of FOXO-1 and its nuclear cytoplasmic localization in the generated IPCs. Afterwards we knocked down FOXO-1 using siRNA targeting FOXO-1 (siFOXO-1). The differentiated siFOXO-1 IPCs were compared to non-targeting siRNA (siNT) IPCs regarding expression of ß-cell markers by qRT-PCR and western blotting, dithizone (DTZ) staining and glucose stimulated insulin secretion (GSIS). KEY FINDINGS: Isolated Ad-MSCs exhibited all characteristics of MSCs and can generate IPCs. FOXO-1 was initially elevated during differentiation followed by a decline towards end of differentiation. FOXO-1 was dephosphorylated and localized to the nucleus upon differentiation into IPCs. Knock down of FOXO-1 improved the expression of ß-cell markers in final differentiated IPCs, improved DTZ uptake and showed increased insulin secretion upon challenging with increased glucose concentration. SIGNIFICANCE: These results portray FOXO-1 as a hindering factor of generation of IPCs whose down-regulation can generate more mature IPCs for MSCs therapy of diabetes mellitus.

Neuroprotective effect of liraglutide in an experimental mouse model of multiple sclerosis: role of AMPK/SIRT1 signaling and NLRP3 inflammasome.

The heterogeneous nature of multiple sclerosis (MS) and the unavailability of treatments addressing its intricate network and reversing the disease state is yet an area that needs to be elucidated. Liraglutide, a glucagon-like peptide-1 analogue, recently exhibited intriguing potential neuroprotective effects. The currents study investigated its potential effect against mouse model of MS and the possible underlying mechanisms. Demyelination was induced in C57Bl/6 mice by cuprizone (400 mg/kg/day p.o.) for 5 weeks. Animals received either liraglutide (25 nmol/kg/day i.p.) or dorsomorphin, an AMPK inhibitor, (2.5 mg/Kg i.p.) 30 min before the liraglutide dose, for 4 weeks (starting from the second week). Liraglutide improved the behavioral profile in cuprizone-treated mice. Furthermore, it induced the re-myelination process through stimulating oligodendrocyte progenitor cells differentiation via Olig2 transcription activation, reflected by increased myelin basic protein and myelinated nerve fiber percentage. Liraglutide elevated the protein content of p-AMPK and SIRT1, in addition to the autophagy proteins Beclin-1 and LC3B. Liraglutide halted cellular damage as manifested by reduced HMGB1 protein and consequently TLR-4 downregulation, coupled with a decrease in NF-κB. Liraglutide also suppressed NLRP3 transcription. Dorsomorphin pre-administration indicated a possible interplay between AMPK/SIRT1 and NLRP3 inflammasome activation as it partially reversed liraglutide's effects. Immunohistochemical examination of Iba+ microglia emphasized these findings. In conclusion, liraglutide exerts neuroprotection against cuprizone-induced demyelination via anti-inflammatory, autophagic flux activation, NLRP3 inflammasome suppression, and anti-apoptotic mechanisms, possibly mediated, at least in part, via AMPK/SIRT1, autophagy, TLR-4/ NF-κB/NLRP3 signaling. The potential mechanistic insight of Lira in alleviating Cup-induced neurotoxicity via: (1) AMPK/SIRT1 pathways activation resulting in the stimulation of brain autophagy flux (confirmed by lowering Beclin-1 and LC3-B protein expression). (2) Inhibition of NLRP3 inflammasome activation, as evidenced by reduced HMGB1, TLR-4, NF-κB and NLRP3 protein expression, alongside diminishing the activation of its downstream cascade as reflected by reduced levels of caspase-1 and IL-1ß protein expression. (3) A possible modulating interplay between the previously mentioned two pathways.

Crosstalk between aldehyde dehydrogenase-1 and chemoresistance in breast cancer: Insights into the role of vitamin D3.

AIMS: Aldehyde dehydrogenase-1 (ALDH-1) is considered a signature of breast cancer stem cells and is linked to poor outcomes in breast cancer patients. This study aimed at investigating the effect of vitamin D3 on enhancing the tumor responsiveness to different conventional chemotherapeutic agents, viz., cisplatin, methotrexate, and doxorubicin. MAIN METHODS: In vitro and in vivo experiments were performed using combinations of vitamin D3 and chemotherapeutic agents. Cell cycle analysis and apoptosis assays were performed. Moreover, ALDH-1 expression levels were estimated in cancer cell lines and solid tumors. For solid tumors, tumor volume and histopathological necrotic indices were estimated. Leukocyte presence was also evaluated in tumors using leukocyte common antigen (LCA). KEY FINDINGS: Results showed a synergistic interaction between vitamin D3 and each of the chemotherapeutic agents on breast cancer cell lines as well as cell cycle arrest at G2/M phase. A decrease in ALDH-1 levels was reported in both breast cancer cells and in tumor tissues. Reductions in tumor volume were also observed in the groups which received the combination therapy. An influence on necrosis rather than apoptosis was also reported, as evidenced by necrotic indices and Bcl-2 expression in tumor sections, respectively. Increased local leukocytes in tumors was also evident, as indicated by increased expression of leukocyte common antigen (LCA). SIGNIFICANCE: Overall, the present study shows that vitamin D3 has an impact on resistance to different chemotherapeutic agents which could be due to the inhibition of ALDH-1, suggesting its use as an adjuvant therapy in cancer patients receiving chemotherapy.

Inhibition of aldehyde dehydrogenase-1 and p-glycoprotein-mediated multidrug resistance by curcumin and vitamin D3 increases sensitivity to paclitaxel in breast cancer.

Treatment of breast cancer by paclitaxel (PAX) often encounters therapeutic failure most likely caused by innate/acquired resistance. Cancer stem cells (CSCs) and multidrug resistance complex (MDR-1 or P-glycoprotein) overexpression are main mechanisms implicated in chemoresistance. Increased aldehyde dehrogenase-1 (ALDH-1) was previously correlated with the stemness features of CSCs and hence is used as a marker for identification and CSCs targeting. The present study, therefore, aimed at investigating the effect of both curcumin (CUR) and vitamin D3 (D3) on MDR-1 and ALDH-1 expression and consequently the resistance to PAX both in vitro and in vivo. CUR was isolated from Turmeric rhizomes and identified using UPLC-ESI-MS/MS. For in vitro studies, the antiproliferative effect of PAX, CUR, 1,25(OH)2D3 (the active form of D3, also known as calcitriol) was determined, each alone and combined (PAX+CUR, PAX+1,25(OH)2D3, and PAX+CUR+1,25(OH)2D3) on MCF-7 breast cancer cells. Ehrlich ascites carcinoma solid tumor animal model was also used for in vivo studies. Combining CUR and/or 1,25(OH)2D3 to PAX showed synergistic cytotoxic interaction on MCF-7 cells. The apoptotic potential was also enhanced, as evidenced by a significant increase in caspase-7 and -9 as well as the pro-apoptotic Bax whereas a decrease in Bcl-2 levels was reported. Combining CUR and 1,25(OH)2D3 to PAX caused a downregulation in both MDR-1 and ALDH-1 gene expression in MCF-7 besides a decrease in their protein levels. In vivo, the triple therapy group (PAX+CUR+D3) showed the least tumor size. It also showed the lowest levels of MDR-1 and ALDH-1. PAX alone, however, showed increased levels of MDR-1 and ALDH-1 compared to control. Overall, the present study showed that PAX, as a monotherapy, demonstrated acquired resistance possibly by increasing MDR-1 expression and enriching CSCs population, as evidenced by increased ALDH-1. However, using CUR and D3 enhanced tumor response to PAX.