No abstract

Reduction-responsive biodegradable micelles were developed from disulfide-linked dextran-b-poly(epsilon-caprolactone) diblock copolymer (Dex-SS-PCL) and applied for triggered release of doxorubicin (DOX) in vitro and inside cells. Dex-SS-PCL was readily synthesized by thiol-disulfide exchange reaction between dextran orthopyridyl disulfide (Dex-SS-py, 6000 Da) and mercapto PCL (PCL-SH, 3100 Da). Dynamic light scattering (DLS) measurements showed that Dex-SS-PCL yielded micelles with an average size of about 60 nm and a low polydispersity index (PDI 0.1-0.2) in PB (50 mM, pH 7.4). Interestingly, these micelles formed large aggregates rapidly in response to 10 mM dithiothreitol (DTT), most likely due to shedding of the dextran shells through reductive cleavage of the intermediate disulfide bonds. DOX could be efficiently loaded into the micelles with a drug loading efficiency of about 70%. Notably, the in vitro release studies revealed that Dex-SS-PCL micelles released DOX quantitatively in 10 h under a reductive environment, mimicking that of the intracellular compartments such as cytosol and the cell nucleus, whereas only about 27% DOX was released from reduction insensitive Dex-PCL micelles in 11.5 h under otherwise the same conditions and about 20% DOX released from Dex-SS-PCL micelles in 20 h under the nonreductive conditions. The cell experiments using fluorescence microscopy and confocal laser scanning microscopy (CLSM) showed clearly that DOX was rapidly released to the cytoplasm as well as to the cell nucleus. MTT studies revealed a markedly enhanced drug efficacy of DOX-loaded Dex-SS-PCL micelles as compared to DOX-loaded reduction-insensitive Dex-PCL micelles. These reduction-responsive biodegradable micelles have appeared highly promising for the targeted intracellular delivery of hydrophobic chemotherapeutics in cancer therapy.

Hepatocellular carcinoma (HCC) is the fifth most common malignancy caused by environmental and genetic factors. MicroRNAs (miRNAs) are a class of short non-coding RNAs with posttranscriptional regulatory functions. They participate in diverse biological pathways and function as gene regulators. Genetic polymorphisms in 3' untranslated regions (3' UTRs) targeted by miRNAs alter the strength of miRNA binding, with consequences on regulation of target genes thereby affecting the individual's cancer risk. We have previously predicted polymorphisms falling in miRNA-binding regions of cancer genes. We selected an insertion/deletion (Indel) polymorphism (rs3783553) in the 3' UTR of interleukin (IL)-1alpha (IL1A) for a case-control study in a Chinese population. With samples from 403 HCC patients and 434 healthy control individuals, strong evidence of association was observed for the variant homozygote. This association was validated in a second independent case-control study with 1074 HCC patients and 1239 healthy control individuals (odds ratio = 0.62; 95% confidence interval = 0.49-0.78). We further show that the 'TTCA' insertion allele for rs3783553 disrupts a binding site for miR-122 and miR-378, thereby increasing transcription of IL-1alpha in vitro and in vivo. These findings suggest that functional polymorphism rs3783553 in IL1A could contribute to HCC susceptibility. Considering IL-1alpha affects not only various phases of the malignant process, such as carcinogenesis, tumor growth and invasiveness, but also patterns of interactions between malignant cells and the host's immune system, our results indicated that IL-1alpha may be a promising target for immunotherapy, early diagnosis and intervention of HCC.

We have recently reported that calreticulin (CRT), a luminal resident protein, can be found in the sera of patients with rheumatoid arthritis and also that recombinant CRT (rCRT) exhibits extraordinarily strong immunological activities. We herein further demonstrate that rCRT fragments 18–412 (rCRT/18-412), rCRT/39-272, rCRT/120-308 and rCRT/120-250 can self-oligomerize in solution and are 50–100 fold more potent than native CRT (nCRT, isolated from mouse livers) in activating macrophages in vitro. We narrowed down the active site of CRT to residues 150–230, the activity of which also depends on dimerization. By contrast, rCRT/18-197 is almost completely inactive. When rCRT/18-412 is fractionated into oligomers and monomers by gel filtration, the oligomers maintain most of their immunological activities in terms of activating macrophages in vitro and inducing specific antibodies in vivo, while the monomers were much less active by comparison. Additionally, rCRT/18-412 oligomers are much better than monomers in binding to, and uptake by, macrophages. Inhibition of macrophage endocytosis partially blocks the stimulatory effect of rCRT/18-412. We conclude that the immunologically active site of CRT maps between residues 198–230 and that soluble CRT could acquire potent immuno-pathological activities in microenvironments favoring its oligomerization.

The pro-inflammatory activity of interleukin 17, which is produced by the IL-23/IL-17 axis, has been associated with the pathogenesis of traumatic brain injury (TBI). The study investigated the potential role of IL-17 in secondary brain injury of TBI in a rat model. Our data showed that the levels of IL-17 increased from 6 h to 7 days and peaked at 3 days, in both the CNS and serum, which were consistent with the severity of secondary brain injury. The IL-23 inhibitor suberoylanilide hydroxamic acid (SAHA) treatment markedly decreased the expressions of IL-17 and apoptosis-associated proteins cleaved caspase-3 and increased the protein ratio of Bcl-2 (B cell lymphoma/leukemia-2)/Bax (Bcl-2-associated X protein). Meanwhile, neuronal apoptosis was reduced, and neural function was improved after SAHA treatment. This study suggests that IL-17 is involved in secondary brain injury after TBI. Administering an IL-23 inhibitor and thereby blocking the IL-23/IL-17 axis may be beneficial in the treatment of TBI.