MiR-494-3p mediates oxaliplatin resistance of colorectal cancer cells via PTEN/AKT pathway

Purpose: To unravel the influence of miR-494-3p on the insensitivity of colorectal cancer (CRC) cells to oxaliplatin.Methods: The mRNA level of miR-494-3p in oxaliplatin-resistant HT-29 cells was evaluated with reverse transcript-polymerase chain reaction (RT-PCR). The cells were treated with miR-494-3p suppressor or mimic, and then apoptotic changes were determined flow cytometrically. Resistancerelated gene expressions were measured using RT-PCR and western blotting. In addition, in vivo mouse experiments were conducted.Results: MiR-494-3p expression in oxaliplatin-resistant HT-29 cells was much higher than that in parental HT-29 cells, accompanied by increased levels of MRP, P-gp, and AKT phosphorylation (p-AKT), and decreased phosphatase and tensin homolog (PTEN) (p < 0.001). The miR-494-3p mimic suppressed oxaliplatin-induced parental HT-29 cell apoptosis, while miR-494-3p inhibitor promoted oxaliplatin-resistant HT-29 cell apoptosis and decreased the levels of p-AKT, MRP and P-gp, while upregulating PTEN (p < 0.001). Furthermore, AKT inhibitor had similar effects as miR-494-3p inhibitor (p < 0.001). Experiments using nude mice demonstrated that inhibition of miR-494-3p accentuated the sensitivity of oxaliplatin-resistant HT-29 cells to oxaliplatin (p < 0.05).Conclusion: Suppression of miR-494-3p attenuates oxaliplatin insensitivity to CRC cells via a mechanism which may involve PTEN/AKT pathway. Therefore, miR-494-3p may be an effective target for overcoming drug resistance of CRC

Enhanced Gene Transfection Efficacy and Safety Through Granular Hydrogel Mediated Gene Delivery Process

Although gene therapy has made great achievements in both laboratory research and clinical translation, there are still challenges such as limited control of drug pharmacokinetics, acute toxicity, poor tissue retention, insufficient efficacy, and inconsistent clinical translation. Herein, a gene therapy gel is formulated by directly redispersing polyplex nanoparticles into granular hydrogels without any gelation pre-treatment, which provides great convenience for storage, dosing and administration. In vitro studies have shown that use of granular hydrogels can regulate the gene drug release, reduce dose dependent toxicity and help improve transfection efficacy. Moreover, the developed gene therapy gel is easy to operate and can be directly used in vitro to evaluate its synergistic efficacy with various gene delivery systems. As such, it represents a major advance over many conventional excipient-based formulations, and new regulatory strategies for gene therapy may be inspired by it

Positioning Error Analysis and Control of a Piezo-Driven 6-DOF Micro-Positioner

This paper presents a positioning error model and a control compensation scheme for a six-degree-of-freedom (6-DOF) micro-positioner based on a compliant mechanism and piezoelectric actuators (PZT). The positioning error model is established by means of the kinematic model of the compliant mechanism and complete differential coefficient theory, which includes the relationships between three typical errors (hysteresis, machining and measuring errors) and the total positioning error. The quantitative analysis of three errors is demonstrated through several experimental studies. Afterwards, an inverse Presiach model-based feedforward compensation of the hysteresis nonlinearity is employed by the control scheme, combined with a proportional-integral-derivative (PID) feedback controller for the compensation of machining and measuring errors. Moreover, a back propagation neural network PID (BP-PID) controller and a cerebellar model articulation controller neural network PID (CMAC-PID) controller are also adopted and compared to obtain optimal control. Taking the translational motion along the X axis as an example, the positioning errors are sharply reduced by the inverse hysteresis model with the maximum error of 12.76% and a root-mean-square error of 4.09%. In combination with the CMAC-PID controller, the errors are decreased to 0.63% and 0.23%, respectively. Hence, simulated and experimental results reveal that the proposed approach can improve the positioning accuracy of 6-DOF for the micro-positioner

Modelling and Analysis of Characteristics of a Piezoelectric-Actuated Micro-/Nano Compliant Platform Using Bond Graph Approach

The piezoelectric-actuated flexure-based compliant platform is commonly adopted in many fields of micro and nanotechnology. In this paper, bond graph modeling, and kinematic and dynamic characteristics of a piezoelectric-actuated micro-/nano compliant platform system are investigated. During modeling, the bond graph model of the piezoelectric actuator (PZT) is derived by considering both the electrical domain and the mechanical domain. Considering the compliances of flexure hinges and elastic linkages, as well as the input ends, the bond graph model for the bridge-type displacement amplification mechanism in the compliant platform is established by combining pseudo-rigid-body (PRB) model theory and elastic beam theory. Based on the interactions between the PZT subsystem and compliant platform subsystem, the kinematic performance of the proposed compliant platform system is evaluated through both computer simulations and experimental tests. Furthermore, the frequency responses, dynamic responses and load capacity of the compliant platform system are studied. This paper explores a new modeling method for a piezoelectric-actuated compliant platform system, which can provide an effective solution when analyzing the micro-/nano system

<i>Para</i>-Aminobenzoic Acid (PABA) Synthase Enhances Thermotolerance of Mushroom <i>Agaricus bisporus</i>

<div><p>Most mushrooms are thermo-sensitive to temperatures over 23°C, which greatly restricts their agricultural cultivation. Understanding mushroom’s innate heat-tolerance mechanisms may facilitate genetic improvements of their thermotolerance. <i>Agaricus bisporus</i> strain <i>02</i> is a relatively thermotolerant mushroom strain, while strain <i>8213</i> is quite thermo-sensitive. Here, we compared their responses at proteomic level to heat treatment at 33°C. We identified 73 proteins that are differentially expressed between <i>02</i> and <i>8213</i> or induced upon heat stress in strain <i>02</i> itself, 48 of which with a known identity. Among them, 4 proteins are constitutively more highly expressed in <i>02</i> than <i>8213</i>; and they can be further upregulated in response to heat stress in <i>02,</i> but not in <i>8213.</i> One protein is encoded by the <i>para</i>-aminobenzoic acid (PABA) synthase gene <i>Pabs</i>, which has been shown to scavenge the reactive oxygen species <i>in vitro</i>. <i>Pabs</i> mRNA and its chemical product PABA show similar heat stress induction pattern as PABA synthase protein and are more abundant in <i>02</i>, indicating transcriptional level upregulation of <i>Pabs</i> upon heat stress. A specific inhibitor of PABA synthesis impaired thermotolerance of <i>02</i>, while exogenous PABA or transgenic overexpression of <i>02</i> derived PABA synthase enhanced thermotolerance of <i>8213</i>. Furthermore, compared to <i>8213</i>, <i>02</i> accumulated less H₂O₂ but more defense-related proteins (e.g., HSPs and Chitinase) under heat stress. Together, these results demonstrate a role of PABA in enhancing mushroom thermotolerance by removing H₂O₂ and elevating defense-related proteins.</p></div

Exogenous PABA improves thermotolerance of strain <i>8213</i>.

<p>(A) Strains <i>02</i> and <i>8213</i> mycelium culture were supplied with or without 5 mg/L PABA, followed by high temperature treatment at 33°C for 48 hours, the images were taken at the indicated time post-heat stress. The control groups were cultured under regular temperature of 23°C. (B) Dose-dependent protection by PABA of mycelium intactness under heat stress at 33°C for 48 hours. Strain <i>02</i> and strain <i>8213</i> were treated with different concentrations of PABA followed by high-temperature treatment at 33°C for 48 h, and the percentage of intact mycelia was counted. The intact mycelia percentage was calculated as compared to the control group (23°C). Three independent biological replicates were performed. Data are expressed as average ± SEM. Unpaired t-tests were performed between samples with and without PABA addition within each strain, respectively, ns: P>0.05, *: P<0.05, **: P<0.01.</p

Exogenous PABA improves thermotolerance of strain <i>8213</i>.

<p>(A) Strains <i>02</i> and <i>8213</i> mycelium culture were supplied with or without 5 mg/L PABA, followed by high temperature treatment at 33°C for 48 hours, the images were taken at the indicated time post-heat stress. The control groups were cultured under regular temperature of 23°C. (B) Dose-dependent protection by PABA of mycelium intactness under heat stress at 33°C for 48 hours. Strain <i>02</i> and strain <i>8213</i> were treated with different concentrations of PABA followed by high-temperature treatment at 33°C for 48 h, and the percentage of intact mycelia was counted. The intact mycelia percentage was calculated as compared to the control group (23°C). Three independent biological replicates were performed. Data are expressed as average ± SEM. Unpaired t-tests were performed between samples with and without PABA addition within each strain, respectively, ns: P>0.05, *: P<0.05, **: P<0.01.</p

2-D electrophoresis of protein extracts from <i>02</i> and <i>8213</i> with or without heat stress (33°C/24 h).

<p>(A) Representative 2-DE gels of mushrooms, identifying 73 proteins with a greater than 2-fold difference after high-temperature treatment (p<0.05). Molecular weight (MW) in kilodaltons and pI of proteins are indicated on the left and top of the gel, respectively. (B) Close-up view of some differentially expressed proteins spots. Three independent replicates were performed. <i>02</i>-NS: <i>02</i> non-stressed (23°C/24 h); <i>02</i>-HS: <i>02</i> heat-stressed (33°C/24 h); <i>8213</i>-NS: <i>8213</i> non-stressed (23°C/24 h); <i>8213</i>-HS: strain <i>8213</i> heat-stressed (33°C/24 h).</p

Transgenic overexpression of PABA synthase improves thermotolerance of strain <i>8213</i>.

<p>(A) Relative mRNA level of <i>Pabs</i> gene of strains <i>02</i>, <i>8213</i> and two <i>Pabs</i>-overexpressing transgenic strains <i>TB-2</i> and <i>TB-3</i> (derived from <i>8213</i>) under normal temperature (23°C) and heat stress (33°C). The mRNA of corresponding samples was extracted and analyzed after 24 hours of treatment. (B) The PABA content of strains <i>02</i>, <i>8213</i> and <i>TB-2</i> and <i>TB-3</i> under normal temperature (23°C) and heat stress (33°C) for 3 days. The PABA content of corresponding samples was extracted and measured after 3 days of treatment. (C) The mycelia growth of Strains <i>02</i>, <i>8213</i> and <i>TB-2</i> and <i>TB-3</i> under normal temperature (23°C) and heat stress (33°C). Mycelia cultures were photographed after 2 weeks of treatment. (D) The mycelia elongation of strains <i>02</i>, <i>8213</i> and <i>TB-2</i> and <i>TB-3</i> under normal temperature (23°C) and heat stress (33°C). The mycelia length is measured after 14 and 21 days of treatment. Three independent biological replicates were performed for each analysis. Data are expressed as average ± SEM. Unpaired t-tests were performed between strain <i>8213</i> and all other strains as indicated within each treatment condition, ns: P>0.05, *: P<0.05, **: P<0.01.</p