Stable DHLA-PEG capped PbS quantum dots: from synthesis to near-infrared biomedical imaging.

The short shelf-life of water-soluble quantum dots (QDs) due to colloidal instability represents a major drawback to their exploitation. This work examines the colloidal stability of PbS nanoparticles capped with dihydrolipoic acid-polyethylene glycol (DHLA-PEG) ligands terminated with functional groups such as -NH2, -COOH, OMe and -N3. and their application for in vivo imaging. We prove a mechanism of colloidal instability and develop a strategy to produce for the first time stable PEG-capped PbS quantum dots with high quantum yield and optical emission in the first and the second near-infrared (NIR) windows of low absorption of biological tissues. The NIR imaging of in vivo biodistribution is demonstrated at wavelengths >1000 nm, with benefits of reduced tissue absorption and light scattering. The stability, biocompatibility and potential for further QD functionalization open up realistic prospects for non-invasive bioimaging applications.

Overexpression of EZH2 in multiple myeloma is associated with poor prognosis and dysregulation of cell cycle control.

Myeloma is heterogeneous at the molecular level with subgroups of patients characterised by features of epigenetic dysregulation. Outcomes for myeloma patients have improved over the past few decades except for molecularly defined high-risk patients who continue to do badly. Novel therapeutic approaches are, therefore, required. A growing number of epigenetic inhibitors are now available including EZH2 inhibitors that are in early-stage clinical trials for treatment of haematological and other cancers with EZH2 mutations or in which overexpression has been correlated with poor outcomes. For the first time, we have identified and validated a robust and independent deleterious effect of high EZH2 expression on outcomes in myeloma patients. Using two chemically distinct small-molecule inhibitors, we demonstrate a reduction in myeloma cell proliferation with EZH2 inhibition, which leads to cell cycle arrest followed by apoptosis. This is mediated via upregulation of cyclin-dependent kinase inhibitors associated with removal of the inhibitory H3K27me3 mark at their gene loci. Our results suggest that EZH2 inhibition may be a potential therapeutic strategy for the treatment of myeloma and should be investigated in clinical studies.

Transdisciplinary synthesis for ecosystem science, policy and management: The Australian experience.

Mitigating the environmental effects of global population growth, climatic change and increasing socio-ecological complexity is a daunting challenge. To tackle this requires synthesis: the integration of disparate information to generate novel insights from heterogeneous, complex situations where there are diverse perspectives. Since 1995, a structured approach to inter-, multi- and trans-disciplinary(1) collaboration around big science questions has been supported through synthesis centres around the world. These centres are finding an expanding role due to ever-accumulating data and the need for more and better opportunities to develop transdisciplinary and holistic approaches to solve real-world problems. The Australian Centre for Ecological Analysis and Synthesis (ACEAS ) has been the pioneering ecosystem science synthesis centre in the Southern Hemisphere. Such centres provide analysis and synthesis opportunities for time-pressed scientists, policy-makers and managers. They provide the scientific and organisational environs for virtual and face-to-face engagement, impetus for integration, data and methodological support, and innovative ways to deliver synthesis products. We detail the contribution, role and value of synthesis using ACEAS to exemplify the capacity for synthesis centres to facilitate trans-organisational, transdisciplinary synthesis. We compare ACEAS to other international synthesis centres, and describe how it facilitated project teams and its objective of linking natural resource science to policy to management. Scientists and managers were brought together to actively collaborate in multi-institutional, cross-sectoral and transdisciplinary research on contemporary ecological problems. The teams analysed, integrated and synthesised existing data to co-develop solution-oriented publications and management recommendations that might otherwise not have been produced. We identify key outcomes of some ACEAS working groups which used synthesis to tackle important ecosystem challenges. We also examine the barriers and enablers to synthesis, so that risks can be minimised and successful outcomes maximised. We argue that synthesis centres have a crucial role in developing, communicating and using synthetic transdisciplinary research.

Restricting direct interaction of CDC37 with HSP90 does not compromise chaperoning of client proteins.

The HSP90 molecular chaperone plays a key role in the maturation, stability and activation of its clients, including many oncogenic proteins. Kinases are a substantial and important subset of clients requiring the key cochaperone CDC37. We sought an improved understanding of protein kinase chaperoning by CDC37 in cancer cells. CDC37 overexpression in human colon cancer cells increased CDK4 protein levels, which was negated upon CDC37 knockdown. Overexpressing CDC37 increased CDK4 protein half-life and enhanced binding of HSP90 to CDK4, consistent with CDC37 promoting kinase loading onto chaperone complexes. Against expectation, expression of C-terminus-truncated CDC37 (ΔC-CDC37) that lacks HSP90 binding capacity did not affect kinase client expression or activity; moreover, as with wild-type CDC37 overexpression, it augmented CDK4-HSP90 complex formation. However, although truncation blocked binding to HSP90 in cells, ΔC-CDC37 also showed diminished client protein binding and was relatively unstable. CDC37 mutants with single and double point mutations at residues M164 and L205 showed greatly reduced binding to HSP90, but retained association with client kinases. Surprisingly, these mutants phenocopied wild-type CDC37 overexpression by increasing CDK4-HSP90 association and CDK4 protein levels in cells. Furthermore, expression of the mutants was sufficient to protect kinase clients CDK4, CDK6, CRAF and ERBB2 from depletion induced by silencing endogenous CDC37, indicating that CDC37's client stabilising function cannot be inactivated by substantially reducing its direct interaction with HSP90. However, CDC37 could not compensate for loss of HSP90 function, showing that CDC37 and HSP90 have their own distinct and non-redundant roles in maintaining kinase clients. Our data substantiate the important function of CDC37 in chaperoning protein kinases. Furthermore, we demonstrate that CDC37 can stabilise kinase clients by a mechanism that is not dependent on a substantial direct interaction between CDC37 and HSP90, but nevertheless requires HSP90 activity. These results have significant implications for therapeutic targeting of CDC37.

Surgical delivery of drug releasing poly(lactic-co-glycolic acid)/poly(ethylene glycol) paste with in vivo effects against glioblastoma.

INTRODUCTION: The median survival of patients with glioblastoma multiforme (astrocytoma grade 4) remains less than 18 months despite radical surgery, radiotherapy and systemic chemotherapy. Surgical implantation of chemotherapy eluting wafers into the resection cavity has been shown to improve length of survival but the current licensed therapy has several drawbacks. This paper investigates in vivo efficacy of a novel drug eluting paste in glioblastoma. METHODS: Poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) self-sintering paste was loaded with the chemotherapeutic agent etoposide and delivered surgically into partially resected tumours in a flank murine glioblastoma xenograft model. RESULTS: Surgical delivery of the paste was successful and practical, with no toxicity or surgical morbidity to the animals. The paste was retained in the tumour cavity, and preliminary results suggest a useful antitumour and antiangiogenic effect, particularly at higher doses. Bioluminescent imaging was not affected significantly by the presence of the paste in the tumour. CONCLUSIONS: Chemotherapy loaded PLGA/PEG paste seems to be a promising technology capable of delivering active drugs into partially resected tumours. The preliminary results of this study suggest efficacy with no toxicity and will lead to larger scale efficacy studies in orthotopic glioblastoma models.

Personalized cancer medicine: molecular diagnostics, predictive biomarkers, and drug resistance.

The progressive elucidation of the molecular pathogenesis of cancer has fueled the rational development of targeted drugs for patient populations stratified by genetic characteristics. Here we discuss general challenges relating to molecular diagnostics and describe predictive biomarkers for personalized cancer medicine. We also highlight resistance mechanisms for epidermal growth factor receptor (EGFR) kinase inhibitors in lung cancer. We envisage a future requiring the use of longitudinal genome sequencing and other omics technologies alongside combinatorial treatment to overcome cellular and molecular heterogeneity and prevent resistance caused by clonal evolution.

Progress in the preclinical discovery and clinical development of class I and dual class I/IV phosphoinositide 3-kinase (PI3K) inhibitors.

The phosphoinositide 3-kinases (PI3Ks) constitute an important family of lipid kinase enzymes that control a range of cellular processes through their regulation of a network of signal transduction pathways, and have emerged as important therapeutic targets in the context of cancer, inflammation and cardiovascular diseases. Since the mid-late 1990s, considerable progress has been made in the discovery and development of small molecule ATP-competitive PI3K inhibitors, a number of which have entered early phase human trials over recent years from which key clinical results are now being disclosed. This review summarizes progress made to date, primarily on the discovery and characterization of class I and dual class I/IV subtype inhibitors, together with advances that have been made in translational and clinical research, notably in cancer.

Evaluation of the LMA Supreme in 100 non-paralysed patients.

We studied the LMA Supreme in 100 elective, anaesthetised, healthy patients assessing: ease of use, airway quality, anatomical and functional positioning, airway leak and complications. Insertion was successful on first, second or third attempt in 90, nine and one patient respectively. Thirty manipulations were required in 22 patients to achieve a clear airway. Median [interquartile (range)] insertion time was 18 [10-25 (5-120)] s. During ventilation, an expired tidal volume of 7 ml x kg(-1) was achieved in all patients. Median [interquartile (range)] airway leak pressure was 24 [20-28 (13-40)] cmH(2)O. On fibreoptic examination via the device, vocal cords were visible in 83 patients (85%). During maintenance, five patients (5%) required 13 airway manipulations. There was one episode of minor regurgitation, without aspiration. Other complications and patient side-effects were mild and few. The LMA Supreme is easily and rapidly inserted, providing a reliable airway and good airway seal. Further studies are indicated to assess safety and performance compared to other supraglottic airway devices.

Silencing the cochaperone CDC37 destabilizes kinase clients and sensitizes cancer cells to HSP90 inhibitors.

The cochaperone CDC37 promotes the association of HSP90 with the protein kinase subset of client proteins to maintain their stability and signalling functions. HSP90 inhibitors induce depletion of clients, which include several oncogenic kinases. We hypothesized that the targeting of CDC37 using siRNAs would compromise the maturation of these clients and increase the sensitivity of cancer cells to HSP90 inhibitors. Here, we show that silencing of CDC37 in human colon cancer cells diminished the association of kinase clients with HSP90 and reduced levels of the clients ERBB2, CRAF, CDK4 and CDK6, as well as phosphorylated AKT. CDC37 silencing promoted the proteasome-mediated degradation of kinase clients, suggesting a degradation pathway independent from HSP90 binding. Decreased cell signalling through kinase clients was also demonstrated by reduced phosphorylation of downstream substrates and colon cancer cell proliferation was subsequently reduced by the inhibition of the G1/S-phase transition. Furthermore, combining CDC37 silencing with the HSP90 inhibitor 17-AAG induced more extensive and sustained depletion of kinase clients and potentiated cell cycle arrest and apoptosis. These results support an essential role for CDC37 in concert with HSP90 in maintaining oncogenic protein kinase clients and endorse the therapeutic potential of targeting CDC37 in cancer.

De-regulation of the sonic hedgehog pathway in the InsGas mouse model of gastric carcinogenesis.

This study investigated sonic hedgehog (Shh) signalling in gastric metaplasia in the insulin-gastrin (InsGas) hypergastrinaemic mouse +/- Helicobacter felis (H. felis) infection. Sonic hedgehog gene and protein expression was reduced in pre-metaplastic lesions from non-infected mice (90% gene reduction, P<0.01) compared to normal mucosa. Sonic hedgehog was reactivated in gastric metaplasia of H. felis-infected mice (3.5-fold increase, P<0.01) compared to pre-metaplastic lesions. Additionally, the Shh target gene, glioma-associated oncogene (Gli)-1, was significantly reduced in the gastric glands of InsGas mice (75% reduction, P<0.05) and reactivated with H. felis infection (P<0.05, base of glands, P<0.01 stroma of metaplastic glands). The ability of H. felis to activate the Shh pathway was investigated by measuring the effect of target cytokine, interleukin-8 (IL-8), on Shh expression in AGS and MGLVA1 cells, which was shown to induce Shh expression at physiological concentrations. H. felis induced the expression of NF-kappaB in inflammatory infiltrates in vivo, and the expression of the IL-8 mouse homologue, protein KC, in inflammatory infiltrates and metaplastic lesions. Sonic hedgehog pathway reactivation was paralleled with an increase in proliferation of metaplastic lesions (15.75 vs 4.39% in infected vs non-infected mice, respectively, P<0.001). Furthermore, Shh overexpression increased the growth rate of the gastric cancer cell line, AGS. The antiapoptotic protein, bcl-2, was expressed in the stroma of infected mice, along with a second Shh target gene, patched-1 (P=0.0001, stroma of metaplastic gland). This study provides evidence suggesting reactivation of Shh signalling from pre-metaplastic to advanced metaplastic lesions of the stomach and outlines the importance of the Shh pathway as a potential chemoprophylactic target for gastric carcinogenesis.

Androgen receptors may act in a paracrine manner to regulate oesophageal adenocarcinoma growth.

BACKGROUND: The role of androgen receptors (ARs) in tumorigenesis, including transcription of fibroblast growth factors (FGFs), is established in prostate cancer. This study examined the role of ARs and FGFs in oesophageal adenocarcinoma (EAC), where tumour incidence in males is higher. METHODS: AR gene expression was analysed using quantitative RT-PCR; AR, fibroblast growth factor receptor-1 (FGFR-1) and fibroblast growth factor-8 isoform b (FGF-8b) protein by immunohistochemistry; and serum steroid levels (testosterone, progesterone, luteinising hormone and follicle stimulating hormone (FSH)) by immunoassay. A human oesophageal adenocarcinoma cell line was grown subcutaneously in nude mice. RESULTS: AR gene expression was of significantly higher levels than oesophageal adenocarcinomas (n=21, p=0.002) and in the squamous carcinoma line (OE21) compared with the adenocarcinoma lines (OE33 and OE19). Median serum testosterone levels in oesophageal carcinoma patients were higher than in age-matched controls (p=0.01) and reduced postoperatively, in patients undergoing curative resection (p=0.006). No significant differences were observed in hormones except FSH, where preoperative levels were significantly higher in the EAC group. AR protein was expressed in normal oesophageal squamous epithelial cells and also in the stroma of 18/23 EAC samples. FGFR-1 protein was expressed in malignant epithelium of 23/23 tumour samples. OE19 xenografts grew faster in male versus female mice (tumour weight at day 21, 1.14 g and 0.28 g, respectively, p=0.005) and had elevated FGF receptor expression. CONCLUSIONS: AR expressed in the stroma of oesophageal adenocarcinomas may induce paracrine effects following stimulation by androgens (including tumour-derived), possibly via FGFs, including FGF-8b.

Characterisation of molecular events following cisplatin treatment of two curable ovarian cancer models: contrasting role for p53 induction and apoptosis in vivo.

The detailed molecular basis and determinants of in vivo tumour sensitivity to conventional anticancer agents remain unclear. We examined the cellular and molecular consequences of cisplatin treatment using two ovarian tumour xenograft models that had not been previously adapted to culture in vitro. Both xenografts were curable with clinically relevant multiple doses of cisplatin. Following a single dose of cisplatin (6 mg kg(-1) i.p.) growth delays of 25 and 75 days were obtained for pxn100 and pxn65, respectively. This difference in response was not due to differences in DNA damage. Pxn100 tumours had a functional p53 response and a wild-type p53 sequence, whereas pxn65 harboured a mutant p53 and lacked a functional p53 response. Microarray analysis revealed the induction of p53-regulated genes and regulators of checkpoint control and apoptosis in pxn100 tumours following cisplatin-treatment. By contrast, there was no p53-dependent response and only limited changes in gene expression were detected in the pxn65 tumours. TUNEL analysis demonstrated high levels of apoptosis in the pxn100 tumours following cisplatin treatment, but there was no detectable apoptosis in the pxn65 tumours. Our observations show that a marked in vivo response to cisplatin can occur via p53-dependent apoptosis or independently of p53 status in human ovarian xenografts.

Potential role of endocrine gastrin in the colonic adenoma carcinoma sequence.

The role of hyper-gastrinaemia in the incidence of colonic cancer remains to be clarified. The aim of this study was to determine whether cholecystokinin-2 (CCK-2) receptor expression predicts the sensitivity of human colonic adenomas to the proliferative effects of serum hyper-gastrinaemia. Gene expression of the classical (74 kDa) CCK-2 receptor in human colonic adenoma specimens and cell lines, was quantified by real-time PCR. Western blotting, using a CCK-2 receptor antiserum, confirmed protein expression. A transformed human colonic adenoma was grown in SCID mice, with hyper-gastrinaemia induced by proton pump inhibitors. CCK-2 receptor blockade was achieved by using neutralising antiserum. Both human colonic adenoma cell lines and biopsies expressed CCK-2 receptor mRNA at levels comparable with CCK-2 receptor transfected fibroblasts and oxyntic mucosa. Western blotting confirmed immunoreactive CCK-2 receptor bands localised to 45, 74 and 82.5 kDa. Omeprazole and lansoprazole-induced hyper-gastrinaemia (resulting in serum gastrin levels of 34.0 and 153.0 pM, respectively) significantly increased the weight of the human adenoma grafts (43% (P=0.016) and 70% (P=0.014), respectively). The effect of hypergastrinaemia on tumour growth was reversed by use of antiserum directed against the CCK-2 receptor. Hyper-gastrinaemia may promote proliferation of human colonic adenomas that express CCK-2 receptor isoforms.

Apoptosis is associated with triacylglycerol accumulation in Jurkat T-cells.

Magnetic resonance spectroscopy is increasingly used as a non-invasive method to investigate apoptosis. Apoptosis was induced in Jurkat T-cells by Fas mAb. (1)H magnetic resonance spectra of live cells showed an increase in methylene signal as well as methylene/methyl ratio of fatty acid side chains at 5 and 24 h following induction of apoptosis. To explain this observation, (1)H magnetic resonance spectra of cell extracts were investigated. These demonstrated a 70.0+/-7.0%, 114.0+/-8.0% and 90.0+/-5.0% increase in the concentration of triacylglycerols following 3, 5 and 7 h of Fas mAb treatment (P<0.05). Confocal microscopy images of cells stained with the lipophilic dye Nile Red demonstrated the presence of lipid droplets in the cell cytoplasm. Quantification of the stained lipids by flow cytometry showed a good correlation with the magnetic resonance results (P > or =0.05 at 3, 5 and 7 h). (31)P magnetic resonance spectra showed a drop in phosphatidylcholine content of apoptosing cells, indicating that alteration in phosphatidylcholine metabolism could be the source of triacylglycerol accumulation during apoptosis. In summary, apoptosis is associated with an early accumulation of mobile triacylglycerols mostly in the form of cytoplasmic lipid droplets. This is reflected in an increase in the methylene/methyl ratio which could be detected by magnetic resonance spectroscopy.

Gene expression microarray analysis in cancer biology, pharmacology, and drug development: progress and potential.

With the imminent completion of the Human Genome Project, biomedical research is being revolutionised by the ability to carry out investigations on a genome wide scale. This is particularly important in cancer, a disease that is caused by accumulating abnormalities in the sequence and expression of a number of critical genes. Gene expression microarray technology is gaining increasingly widespread use as a means to determine the expression of potentially all human genes at the level of messenger RNA. In this commentary, we review developments in gene expression microarray technology and illustrate the progress and potential of the methodology in cancer biology, pharmacology, and drug development. Important applications include: (a) development of a more global understanding of the gene expression abnormalities that contribute to malignant progression; (b) discovery of new diagnostic and prognostic indicators and biomarkers of therapeutic response; (c) identification and validation of new molecular targets for drug development; (d) provision of an improved understanding of the molecular mode of action during lead identification and optimisation, including structure-activity relationships for on-target versus off-target effects; (e) prediction of potential side-effects during preclinical development and toxicology studies; (f) confirmation of a molecular mode of action during hypothesis-testing clinical trials; (g) identification of genes involved in conferring drug sensitivity and resistance; and (h) prediction of patients most likely to benefit from the drug and use in general pharmacogenomic studies. As a result of further technological improvements and decreasing costs, the use of microarrays will become an essential and potentially routine tool for cancer and biomedical research.

Preclinical antitumor activity and pharmacodynamic studies with the farnesyl protein transferase inhibitor R115777 in human breast cancer.

Antitumor and pharmacodynamic studies were performed in MCF-7 human breast cancer cells and companion xenografts with the farnesyl protein transferase inhibitor, R115777, presently undergoing Phase II clinical trials, including in breast cancer. R115777 inhibited growth of MCF-7 cells in vitro with an IC(50) of 0.31 +/- 0.25 microM. Exposure of MCF-7 cells to increasing concentrations of R115777 for 24 h resulted in the inhibition of protein farnesylation, as indicated by the appearance of prelamin A at concentrations >1 microM. After continuous exposure to 2 microM R115777, prelamin A levels peaked at 2 h post drug exposure and remained high for up to 72 h. R115777 administered p.o. twice daily for 10 consecutive days to mice bearing established s.c. MCF-7 xenografts induced tumor inhibition at a dose of 25 mg/kg [percentage of treated versus control (% T/C) = 63% at day 21]. Greater inhibition was observed at doses of 50 mg/kg (% T/C at day 21 = 38%) or 100 mg/kg (% T/C at day 21 = 43%). The antitumor effect appeared to be mainly cytostatic with little evidence of tumor shrinkage to less than the starting volume. Tumor response correlated with an increase in the appearance of prelamin A, but no changes in the prenylation of lamin B, heat shock protein 40, or N-Ras were detectable. In addition, significant increases in apoptotic index and p21(WAF1/CIP1) expression were observed, concomitant with a decrease in proliferation as measured by Ki-67 staining. An increase in prelamin A was also observed in peripheral blood lymphocytes in a breast cancer patient who responded to R115777. These data show that R115777 possesses preclinical antitumor activity against human breast cancer and that the appearance of prelamin A may provide a sensitive and convenient pharmacodynamic marker of inhibition of prenylation and/or response.

Inhibition of signal transduction by the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin results in cytostasis and apoptosis.

17-Allylamino-17-demethoxygeldanamycin (17AAG) is a first-in-class heat shock protein 90 (Hsp90) molecular chaperone inhibitor to enter clinical trials. The downstream molecular and cellular consequences of Hsp90 inhibition are not well defined. 17AAG has shown activity against human colon cancer in cell culture and xenograft models. In this study, we demonstrated that in addition to depleting c-Raf-1 and inhibiting ERK-1/2 phosphorylation in human colon adenocarcinoma cells, 17AAG also depleted N-ras, Ki-ras, and c-Akt and inhibited phosphorylation of c-AKT: A consequence of these events was the induction of cell line-dependent cytostasis and apoptosis, although the latter did not result from dephosphorylation of proapoptotic BAD: One cell line, KM12, did not exhibit apoptosis and in contrast to the other cell lines overexpressed Bag-1, but did not express BAX: Taken together with other determinants of 17AAG sensitivity, these results should contribute to a more complete understanding of the molecular pharmacology of 17AAG, which in turn should aid the future rational clinical development and use of the drug in colon and other tumor types.

Expression of gastrin in developing gastric adenocarcinoma.

BACKGROUND: A stepwise progression through premalignant stages has been identified for the intestinal type of gastric carcinoma. As gastrin has been identified as a growth factor for the intestinal type of gastric adenocarcinoma, the aim of this study was to investigate whether gastrin is expressed in premalignant gastric conditions. METHODS: Ninety archival samples of atrophic gastritis, intestinal metaplasia, mild gastric epithelial dysplasia, moderate gastric epithelial dysplasia, severe gastric epithelial dysplasia and intestinal-type gastric adenocarcinoma were obtained. Immunocytochemistry was performed using antibodies directed against gastrin and its post-translational precursors, and the gastrin/cholecystokinin B receptor. Positive staining was identified using the avidin--biotin immunoperoxidase method and quantified using an image analysis system. RESULTS: Gastrin and its receptor were shown to be expressed in specimens of atrophic gastritis, intestinal metaplasia, epithelial dysplasia and the intestinal type of gastric carcinoma. CONCLUSION: Gastrin seems to be an important growth factor in gastric carcinogenesis.