Non-Phosphorylatable PEA-15 Sensitises SKOV-3 Ovarian Cancer Cells to Cisplatin

The efficacy of cisplatin-based chemotherapy in ovarian cancer is often limited by the development of drug resistance. In most ovarian cancer cells, cisplatin activates extracellular signal-regulated kinase1/2 (ERK1/2) signalling. Phosphoprotein enriched in astrocytes (PEA-15) is a ubiquitously expressed protein, capable of sequestering ERK1/2 in the cytoplasm and inhibiting cell proliferation. This and other functions of PEA-15 are regulated by its phosphorylation status. In this study, the relevance of PEA-15 phosphorylation state for cisplatin sensitivity of ovarian carcinoma cells was examined. The results of MTT-assays indicated that overexpression of PEA-15AA (a non-phosphorylatable variant) sensitised SKOV-3 cells to cisplatin. Phosphomimetic PEA-15DD did not affect cell sensitivity to the drug. While PEA-15DD facilitates nuclear translocation of activated ERK1/2, PEA-15AA acts to sequester the kinase in the cytoplasm as shown by Western blot. Microarray data indicated deregulation of thirteen genes in PEA-15AA-transfected cells compared to non-transfected or PEA-15DD-transfected variants. Data derived from The Cancer Genome Atlas (TCGA) showed that the expression of seven of these genes including EGR1 (early growth response protein 1) and FLNA (filamin A) significantly correlated with the therapy outcome in cisplatin-treated cancer patients. Further analysis indicated the relevance of nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signalling for the favourable effect of PEA-15AA on cisplatin sensitivity. The results warrant further evaluation of the PEA-15 phosphorylation status as a potential candidate biomarker of response to cisplatin-based chemotherapy. View Full-Tex

Event-triggered logical flow control for comprehensive process integration of multi-step assays on centrifugal microfluidic platforms

Content in the UH Research Archive is made available for personal research, educational, and non-commercial purposes only. Unless otherwise stated, all content is protected by copyright, and in the absence of an open license, permissions for further re-use should be sought from the publisher, the author, or other copyright holder.The centrifugal "lab-on-a-disc" concept has proven to have great potential for process integration of bioanalytical assays, in particular where ease-of-use, ruggedness, portability, fast turn-around time and cost efficiency are of paramount importance. Yet, as all liquids residing on the disc are exposed to the same centrifugal field, an inherent challenge of these systems remains the automation of multi-step, multi-liquid sample processing and subsequent detection. In order to orchestrate the underlying bioanalytical protocols, an ample palette of rotationally and externally actuated valving schemes has been developed. While excelling with the level of flow control, externally actuated valves require interaction with peripheral instrumentation, thus compromising the conceptual simplicity of the centrifugal platform. In turn, for rotationally controlled schemes, such as common capillary burst valves, typical manufacturing tolerances tend to limit the number of consecutive laboratory unit operations (LUOs) that can be automated on a single disc. In this paper, a major advancement on recently established dissolvable film (DF) valving is presented; for the very first time, a liquid handling sequence can be controlled in response to completion of preceding liquid transfer event, i.e. completely independent of external stimulus or changes in speed of disc rotation. The basic, event-triggered valve configuration is further adapted to leverage conditional, large-scale process integration. First, we demonstrate a fluidic network on a disc encompassing 10 discrete valving steps including logical relationships such as an AND-conditional as well as serial and parallel flow control. Then we present a disc which is capable of implementing common laboratory unit operations such as metering and selective routing of flows. Finally, as a pilot study, these functions are integrated on a single disc to automate a common, multi-step lab protocol for the extraction of total RNA from mammalian cell homogenate.Peer reviewe

Paper imbibition for timing of multi-step liquid handling protocols on event-triggered centrifugal microfluidic lab-on-a-disc platforms

This document is the Accepted Manuscript version of the following article: David J. Kinahan, Sinéad M. Kearney, Olivier P. Faneuil, Macdara T. Glynn, Nikolay Dimov, and Jens Ducrée, ‘Paper imbibition for timing of multi-step liquid handling protocols on event-triggered centrifugal microfluidic lab-on-a-disc platforms’, RSC Advances, Vol. 5 (3): 1818-1826, 2015, doi: https://doi.org/10.1039/C4RA14887H, published by the Royal Society of Chemistry.Rotational microfluidic platforms have attracted swiftly growing interest over the last decade due to their suitability for integration and automation of sample preparation and detection. Valving is of pivotal importance on these compact "Lab-on-a-Disc" (LoaD) platforms as all liquids are exposed to the same centrifugal field. A number of valving technologies have been developed to coordinate timing of serial and/or parallel multi-step/multi-liquid assay protocols comprising of laboratory unit operations (LUOs) such as the release, metering and mixing of sample and reagents. So far these valving techniques could be broadly categorised into rotationally controlled or externally actuated schemes. Only recently a new, "event-triggered" flow control has been introduced. In this approach, a valve is opened upon arrival of a liquid at a defined destination on the disc; this innovative mechanism for the first time permits the cascading of LUOs independent of the spin rate. In one technology, dissolvable films (DFs) are configured with a pneumatic chamber to offer function akin to an electrical relay. Dissolving one DF, termed the control film (CF), results in the release of liquid at a distal location through a so-called load film (LF). In this paper, a new method for temporal control of actuating DF-based, event-triggered CFs which are serially aligned at defined distances along a paper strip is introduced. Liquids are transported through the paper strip at a given velocity, thus setting well-defined intervals between subsequent LUOs, e.g. incubation steps. As a proof-of-concept, we present a disc with integrated metering and mixing which can perform a prototypical, 4-fold serial dilution; a common function in bioanalytical protocols. Imbibition of the paper strip sequentially opens five valves for serial dilution and mixing. To illustrate an unprecedented level of on-disc automation, this is followed by a branched cascade of 17 event-triggered valves (for a total of 22 liquid handling steps) which completes the serial dilution protocol.Peer reviewedFinal Accepted Versio

Do families shape corporate board structure in emerging economies?

This study investigates whether there are significant differences in corporate board structure between family and non-family firms using listed companies in Bangladesh where family firms are the most dominant form of public companies. The results of this study suggest that family firms in Bangladesh adopt a distinctly different board structure from non-family firms. In particular, this study finds that family firms have a lower proportion of independent directors and foreign directors than non-family firms. Further, family firms have smaller boards than non-family firms. However, family firms are likely to have more CEO duality and female directors than their non-family counterparts. The findings of this study contribute to extant research on corporate board structure. The overall findings of this study imply that families of Bangladeshi firms have a different board structure compared to non-family firms, and the structure appears to promote a close locus of control for families that facilitates family dominance to prevail

Phosphoprotein Enriched in Astrocytes 15 kDa (PEA-15) Reprograms Growth Factor Signaling by Inhibiting Threonine Phosphorylation of Fibroblast Receptor Substrate 2α

Changes in expression of PEA-15 contribute to diabetes, tumor invasion, and cellular senescence. PEA-15 increases activation of the ERK MAP kinase pathway; the present study shows that it does so by interfering with ERK1/2 phosphorylation of FRS2, terminator of downstream signaling from FGF receptors