A Transgenic Model Reveals the Role of Klotho in Pancreatic Cancer Development and Paves the Way for New Klotho-Based Therapy.

Klotho is an anti-aging transmembrane protein, which can be shed and can function as a hormone. Accumulating data indicate that klotho is a tumor suppressor in a wide array of malignancies, and designate the subdomain KL1 as the active region of the protein towards this activity. We aimed to study the role of klotho as a tumor suppressor in pancreatic ductal adenocarcinoma (PDAC). Bioinformatics analyses of The Cancer Genome Atlas (TCGA) datasets revealed a correlation between the survival of PDAC patients, levels of klotho expression, and DNA methylation, and demonstrated a unique hypermethylation pattern of klotho in pancreatic tumors. The in vivo effects of klotho and KL1 were examined using three mouse models. Employing a novel genetic model, combining pancreatic klotho knockdown with a mutation in Kras, the lack of klotho contributed to PDAC generation and decreased mousece survival. In a xenograft model, administration of viral particles carrying sKL, a spliced klotho isoform containing the KL1 domain, inhibited pancreatic tumors. Lastly, treatment with soluble sKL prolonged survival of Pdx1-Cre; KrasG12D/+;Trp53R172H/+ (KPC) mice, a model known to recapitulate human PDAC. In conclusion, this study provides evidence that klotho is a tumor suppressor in PDAC. Furthermore, these data suggest that the levels of klotho expression and DNA methylation could have prognostic value in PDAC patients, and that administration of exogenous sKL may serve as a novel therapeutic strategy to treat PDAC.

Mitochondrial augmentation of CD34+ cells from healthy donors and patients with mitochondrial DNA disorders confers functional benefit.

Mitochondria are cellular organelles critical for numerous cellular processes and harboring their own circular mitochondrial DNA (mtDNA). Most mtDNA associated disorders (either deletions, mutations, or depletion) lead to multisystemic disease, often severe at a young age, with no disease-modifying therapies. Mitochondria have a capacity to enter eukaryotic cells and to be transported between cells. We describe a method of ex vivo augmentation of hematopoietic stem and progenitor cells (HSPCs) with normal exogenous mitochondria, termed mitochondrial augmentation therapy (MAT). Here, we show that MAT is feasible and dose dependent, and improves mitochondrial content and oxygen consumption of healthy and diseased HSPCs. Ex vivo mitochondrial augmentation of HSPCs from a patient with a mtDNA disorder leads to superior human engraftment in a non-conditioned NSGS mouse model. Using a syngeneic mouse model of accumulating mitochondrial dysfunction (Polg), we show durable engraftment in non-conditioned animals, with in vivo transfer of mitochondria to recipient hematopoietic cells. Taken together, this study supports MAT as a potential disease-modifying therapy for mtDNA disorders.

Two-component cross-linkable gels for fabrication of solid oral dosage forms.

Current three-dimensional (3D) printing techniques involve the solidification of the injected materials by means of UV irradiation, evaporation of organic solvents, or harsh heating and cooling processes. These methods limit the printing of many sensitive bio-active molecules such as proteins. We describe a novel 3D printing technique based on two complementary liquid copolymers, PEG4-PCL-SC and PEG4-PCL-NH2, that are injected in a coordinated fashion and react with each other to form a pre-designed 3D pill. Printed pills swelled about 400% over 3 h, followed by moderate disintegration. Both prednisone and bovine serum albumin were incorporated into the printed pill, but while most of the prednisone was released depending on the ratio between the two complementary pre-polymers, only 40% of the bovine serum albumin was released from the pill. This unique 3D printing apparatus can be used to produce pills at home when the required medication does not handle current production techniques well and may have other possible biomedical applications. However, before this system can be considered for pharmaceutical applications, the low printing resolution, attributable to the slow gelation kinetics and the viscosity of the pre-polymers, should be addressed.

Local Toxicity of Topically Administrated Thermoresponsive Systems: In Vitro Studies with In Vivo Correlation.

Thermoresponsive materials have the ability to respond to a small change in temperature-a property that makes them useful in a wide range of applications and medical devices. Although very promising, there is only little conclusive data about the cytotoxicity and tissue toxicity of these materials. This work studied the biocompatibility of three Food and Drug Administration approved thermoresponsive polymers: poly( N-isopropyl acrylamide), poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) tri-block copolymer, and poly(lactic acid-co-glycolic acid) and poly(ethylene glycol) tri-block copolymer. Fibroblast NIH 3T3 and HaCaT keratinocyte cells were used for the cytotoxicity testing and a mouse model for the in vivo evaluation. In vivo results generally showed similar trends as the results seen in vitro, with all tested materials presenting a satisfactory biocompatibility in vivo. pNIPAM, however, showed the highest toxicity both in vitro and in vivo, which was explained by the release of harmful monomers and impurities. More data focusing on the biocompatibility of novel thermoresponsive biomaterials will facilitate the use of existing and future medical devices.

Klotho response to treatment with growth hormone and the role of IGF-I as a mediator.

CONTEXT: Klotho is an aging-modulating protein expressed mainly in the kidneys, which can be cleaved and shed to act as a circulating hormone. Several lines of evidence suggest a tight interaction between klotho and the GH-IGF-I axis. We showed previously that klotho levels are decreased in pediatric patients with growth hormone deficiency (GHD). Our aim now is to investigate the effect of GH therapy on klotho levels in these patients and to elucidate the role of IGF-1 in mediating secretion of klotho. BASIC PROCEDURES: Klotho levels were measured in 29 GHD pediatric patients (males=15, aged 12.2±3.3years), treated with GH for 2.5±2.8years; nineteen patients had samples obtained both before and during treatment. The effect of IGF-I and its downstream effectors on secretion of klotho to media was studied in COS-7 cells overexpressing klotho. MAIN FINDINGS: Klotho levels increased under GH treatment (from 1321±691pg/ml to 3380±2120pg/ml, p<0.001), and were higher compared to controls (1645±778pg/ml, p<0.001), resulting in supraphysiological levels. Fold-increase in klotho correlated with fold-increase in IGF-I (r=0.63, p=0.004). Studies in COS-7 cells overexpressing klotho revealed mTOR-dependent induction of klotho shedding by IGF-I. PRINCIPAL CONCLUSIONS: Klotho levels increased during GH treatment of pediatric GHD patients. This increase was associated with an increase in IGF-I levels. Furthermore, we showed, for the first time, a direct role of IGF-I in the regulation of klotho's shedding which depends on activation of the AKT-mTOR pathway. Our findings add further support for the close association between klotho and the GH/IGF-I axis.

Paracrine regulation of glioma cells invasion by astrocytes is mediated by glial-derived neurotrophic factor.

It was suggested that the brain microenvironment plays a role in glioma progression. Here we investigate the mechanism by which astrocytes which are abundant in glioma tumors, promote cancer cell invasion. In this study, we evaluated the effects of astrocytes on glioma biology both in vitro and in vivo and determined the downstream paracrine effect of glial-derived neurotrophic factor (GDNF) on tumor invasion. Astrocytes-conditioned media (ACM) significantly increased human and murine glioma cells migration compared to controls. This effect was inhibited when the activity of GDNF on glioma cells was blocked by RET-Fc chimera or anti-GDNF Ab and by small interfering RNA directed against GDNF expression by astrocytes. Glioma cells incubated with ACM led to time dependent phosphorylation of the GDNF receptor, RET and downstream activation of AKT. Tumor migration and GDNF-RET-AKT activation was inhibited by the RET small-molecule inhibitor pyrazolopyrimidine-1 (PP1) and by the AKT inhibitor LY294002. Finally, blocking of RET by PP1 or knockout of the RET coreceptor GFRα1 in glioma cells reduced the size of brain tumors in immunocompetent mice. We suggest a mechanism by which astrocytes attracted to the glioma tumors facilitate brain invasion by secretion of GDNF and activation of RET/GFRα1 receptors expressed by the cancer cells.

Characterization of the melanoma brain metastatic niche in mice and humans.

Brain metastases occur in 15% of patients with melanoma and are associated with a dismal prognosis. Here, we investigate the architectural phenotype and stromal reaction of melanoma brain metastasis in mice and humans. A syngeneic, green fluorescence protein (GFP)-expressing murine B16-F1 melanoma clone was introduced via intracardiac injection, and was examined in vivo in comparison with human specimens. Immunofluorescence analyses of the brain metastases revealed that F4/80(+) macrophages/microglia were most abundant at the tumor front, but rare in its core, where they were found only around blood vessels (P = 0.01). Similar pattern of infiltration was found in CD3(+) T cells (P < 0.01). Infiltrating T cells were prominently CD4(+) compared with CD8(+) T cells (P < 0.001). Blood vessels (CD31(+)) were less abundant at the tumor front than in its center (12 ± 1 vs. 4 ± 0.6 vessels per high-power field [HPF], P < 0.001). In contrast, there were few vessels at the tumor front, but their diameter was significantly larger at the front (8236 µm(2) vs. 4617 µm(2) average cross-sectional area, P < 0.005). This is the first comparative analysis of melanoma brain metastases showing similar stromal reaction in murine models and human specimens. Our results validate the utility of this murine model of melanoma brain metastases for investigating the mechanism of the human disease.