Involvement of p21 (waf1) in merlin deficient sporadic vestibular schwannomas

Previous studies have demonstrated that merlin acts as a tumor suppressor by blocking Ras-mediated signaling. However, the mechanism by which merlin controls cell proliferation has remained obscure. Here we show that merlin deficient tumors exhibited loss of p21, concomitant with elevated CDKs/cyclin D1 levels in sporadic vestibular schwannomas (VS) from clinic patients. Likewise, silencing of merlin gene expression in the cell lines resulted in down-regulation of p21. Furthermore, we find that merlin-enhanced p21 protein stability, rather than increased RNA accumulation, was responsible for the elevated p21 levels. Interestingly, p21 was required to maintain merlin levels and the inhibitory effect of merlin on Ras signaling was partially overridden by knockdown of p21. Consistent with the observation that over-expression of merlin arrested cell growth at G1-phase, the current study indicates that merlin exerts its antiproliferative effect, at least in part, by maintaining p21 expression, and loss of p21 is a prominent feature of merlin deficient schwannomas.

ERG oncoprotein expression in prostate cancer: clonal progression of ERG-positive tumor cells and potential for ERG-based stratification

Gene fusions prevalent in prostate cancer (CaP) lead to the elevated expression of the ERG proto-oncogene. ERG activation present in 50–70% of prostate tumors underscores one of the most common oncogenic alterations in CaP. Despite numerous reports of gene fusions and mRNA expression, ERG oncoprotein status in CaP still remains to be defined. Furthermore, development of ERG protein-based assays may provide a new dimension to evaluation of gene fusions involving diverse androgen-regulated promoters and the ERG protein-coding sequence. Through exhaustive evaluations of 132 whole-mount prostates (261 tumor foci and over 200 000 benign glands) for the ERG oncoprotein nuclear expression, we demonstrated 99.9% specificity for detecting prostate tumor cells using a highly specific anti-ERG monoclonal antibody. The ERG oncoprotein expression correlated well with fusion transcript or gene fusion in randomly selected specimens. Strong concordance of ERG-positive foci of prostatic intraepithelial neoplasia (PIN) with ERG-positive carcinoma (82 out of 85 sections with PIN, 96.5%) affirms the biological role of ERG in clonal selection of prostate tumors in 65% (86 out of 132) of patients. Conversely, ERG negative PINs were associated with ERG-negative carcinoma. Taken together, the homogeneous and strong ERG expression detected in individual tumors establishes the potential for ERG oncoprotein-based stratification of CaP.

The functional significance of microRNA-145 in prostate cancer

Background:

MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in numerous cellular processes. Recent studies have shown aberrant expression of miRNAs in prostate cancer tissues and cell lines. On the basis of miRNA microarray data, we found that miR-145 is significantly downregulated in prostate cancer.

Methods and results:

We investigated the expression and functional significance of miR-145 in prostate cancer. The expression of miR-145 was low in all the prostate cell lines tested (PC3, LNCaP and DU145) compared with the normal cell line, PWR-1E, and in cancerous regions of human prostate tissue when compared with the matched adjacent normal. Overexpression of miR-145 in PC3-transfected cells resulted in increased apoptosis and an increase in cells in the G2/M phase, as detected by flow cytometry. Investigation of the mechanisms of inactivation of miR-145 through epigenetic pathways revealed significant DNA methylation of the miR-145 promoter region in prostate cancer cell lines. Microarray analyses of miR-145-overexpressing PC3 cells showed upregulation of the pro-apoptotic gene TNFSF10, which was confirmed by real-time PCR and western analysis.

Conclusion:

One of the genes significantly upregulated by miR-145 overexpression is the proapoptotic gene TNFSF10. Therefore, modulation of miR-145 may be an important therapeutic approach for the management of prostate cancer.

Microbial transformation of Ibuprofen by a nocardia species

The carboxylic acid functional group of ibuprofen [alpha-methyl-4-(2-methylpropyl) benzene acetic acid] is reduced to the corresponding alcohol and subsequently esterified to the acetate derivative by cultures of Nocardia species strain NRRL 5646. The alcohol and ester microbial transformation products were isolated, and their structures were determined by H and C nuclear magnetic resonance spectroscopy and mass spectrometry. By derivatization of synthetic and microbiologically produced ibuprofen alcohols with S(+)-O-acetylmandelic acid, nuclear magnetic resonance analysis indicated that the carboxylic acid reductase of Nocardia sp. is R enantioselective, giving alcohol products with an enantiomeric excess of 61.2%. The R enantioselectivity of the carboxylic acid reductase enzyme system was confirmed by using cell extracts together with ATP and NADPH in the reduction of isomeric ibuprofens.

Critical molecular pathways in cancer stem cells of chronic myeloid leukemia

Inhibition of BCR-ABL with kinase inhibitors in the treatment of Philadelphia-positive (Ph(+)) chronic myeloid leukemia (CML) is highly effective in controlling but not curing the disease. This is largely due to the inability of these kinase inhibitors to kill leukemia stem cells (LSCs) responsible for disease relapse. This stem cell resistance is not associated with the BCR-ABL kinase domain mutations resistant to kinase inhibitors. Development of curative therapies for CML requires the identification of crucial molecular pathways responsible for the survival and self-renewal of LSCs. In this review, we will discuss our current understanding of these crucial molecular pathways in LSCs and the available therapeutic strategies for targeting these stem cells in CML.

Genotype-dependent effects of inhibitors of the organic cation transporter, OCT1: predictions of metformin interactions

Common genetic variants of the liver-specific human organic cation transporter 1 (OCT1; SLC22A1) have reduced transport capacity for substrates such as the antidiabetic drug metformin. The effect of the reduced OCT1 function on drug interactions associated with OCT1 has not been investigated and was, therefore, the focus of the study presented here. HEK293 cells expressing human OCT1-reference or the variants R61C, V408M, M420del and G465R were first used to study the kinetics and inhibition pattern of the OCT1 substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP(+)). In the second part OCT1-mediated (14)C-metformin uptake was studied in the presence of drugs administered concomitantly with metformin. Transport studies using ASP(+) showed that the function of the variants decreased in the following order: OCT1-reference=V408M=M420del >R61C >>G465R. Variants M420del and R61C were more sensitive to drug inhibition, with IC(50) values up to 23 times lower than those of the OCT1-reference. Uptake studies using (14)C-metformin were in qualitative agreement with those using ASP(+), with the exception that a larger reduction in transport capacity was observed for M420del. Concomitantly administered drugs, such as verapamil and amitriptyline, revealed potential drug-drug interactions at clinical plasma concentrations of metformin for OCT1-M420del.

Flow field effect transistors with polarisable interface for EOF tunable microfluidic separation devices

A method is proposed to control the zeta potential in microchannels using electrically polarisable interfaces in direct contact with the electrolyte. The approach is based on the use of conducting layers exhibiting minimal electrochemical reactions with aqueous electrolytes but a large potential window (typically from -2 V to +2 V) enabling tuning their zeta potential without detrimental faradic reactions. SiC, Al and CN(x) interfaces were deposited on glass surfaces and then integrated into glass-PDMS-glass devices. The effect of the zeta potential control was monitored by measuring the electro-osmotic flow using a microfluidic Wheatstone Bridge. The experimental results are in good agreement with theoretical predictions based on a one dimensional modeling. The electro-osmotic flow control obtained at high pH values suggests that it should be possible to use such devices as Polarisable Interface Flow-Field Effect Transistors (PI-FFETs) to overcome the difficulties met with conventional metal-isolator-electrolyte systems (MIE-FFETs) for electrokinetic separation applications.