Detergent-free parasite transformation and replication assay for drug screening against intracellular Leishmania amastigotes.

Leishmaniasis is an infectious disease caused by protozoan species in the genera Leishmania and Endotrypanum. Current antileishmanial drugs are limited due to adverse effects, variable efficacy, the development of resistant parasites, high cost, parenteral administration and lack of availability in endemic areas. Therefore, active searching for new antileishmanial drugs has been done for years, mainly by academia. Drug screening techniques have been a challenge since the intracellular localization of Leishmania amastigotes implies that the host cell may interfere with the quantification of the parasites and the final estimation of the effect. One of the procedures to avoid host cell interference is based on its detergent-mediated lysis and subsequent transformation of viable amastigotes into promastigotes, their proliferation and eventual quantification as an axenic culture of promastigotes. However, the use of detergent involves additional handling of cultures and variability. In the present work, cultures of intracellular amastigotes were incubated for 72 h at 26 °C after exposure to the test compounds and the transformation and proliferation of parasites took place without need of adding any detergent. The assay demonstrated clear differentiation of negative and positive controls (average Z´ = 0.75) and 50% inhibitory concentrations of compounds tested by this method and by the gold standard enumeration of Giemsa-stained cultures were similar (p = 0.5002) and highly correlated (r = 0.9707). This simplified procedure is less labor intensive, the probability of contamination and the experimental error are reduced, and it is appropriate for the automated high throughput screening of compounds.

Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction.

BACKGROUND: Helminth infections are an important public health problem in humans and have an even greater impact on domestic animal and livestock welfare. Current readouts for anthelmintic drug screening assays are stage development, migration, or motility that can be subjective, laborious, and low in throughput. The aim of this study was to apply and optimize a fluorometric technique using resazurin for evaluating changes in the metabolic activity of Ascaris suum third-stage larvae (L3), a parasite of high economic relevance in swine. METHODS: Ascaris suum L3 were mechanically hatched from 6- to 8-week embryonated and sucrose-gradient-enriched eggs. Resazurin dye and A. suum L3 were titrated in 96-well microtiter plates, and resazurin reduction activity was assessed by fluorometry after 24 h of incubation. Fluorescence microscopy was used to localize the resazurin reduction site within the larvae. Finally, we exposed A. suum L3 to various stress conditions including heat, methanol, and anthelmintics, and investigated their impact on larval metabolism through resazurin reduction activity. RESULTS: We show that the non-fluorescent dye resazurin is reduced inside vital A. suum L3 to fluorescent resorufin and released into the culture media. Optimal assay parameters are 100-1000 L3 per well, a resazurin concentration of 7.5 µg/ml, and incubation at 37 °C/5% CO2 for 24 h. An intact L2 sheath around the L3 of A. suum completely prevents the uptake of resazurin, while in unsheathed L3, the most intense fluorescence signal is observed along the larval midgut. L3 exposed to methanol or heat show a gradually decreased resazurin reduction activity. In addition, 24 h exposure to ivermectin at 0.625 µM, mebendazole at 5 µM, and thiabendazole from 10 to 100 µM significantly decreased larval metabolic activity by 55%, 73%, and 70% to 89%, respectively. CONCLUSIONS: Together, our results show that both metabolic stressors and anthelmintic drugs significantly and reproducibly reduce the resazurin reduction activity of A. suum L3, making the proposed assay a sensitive and easy-to-use method to evaluate metabolic activity of A. suum L3 in vitro.

MITF deficiency and oncogenic GNAQ each promote proliferation programs in zebrafish melanocyte lineage cells.

Uveal melanoma (UM) is the most common primary malignancy of the adult eye but lacks any FDA-approved therapy for the deadly metastatic disease. Thus, there is a great need to dissect the driving mechanisms for UM and develop strategies to evaluate potential therapeutics. Using an autochthonous zebrafish model, we previously identified MITF, the master melanocyte transcription factor, as a tumor suppressor in GNAQQ209L -driven UM. Here, we show that zebrafish mitfa-deficient GNAQQ209L -driven tumors significantly up-regulate neural crest markers, and that higher expression of a melanoma-associated neural crest signature correlates with poor UM patient survival. We further determined how the mitfa-null state, as well as expression of GNAQQ209L , YAPS127A;S381A , or BRAFV600E oncogenes, impacts melanocyte lineage cells before they acquire the transformed state. Specifically, examination 5 days post-fertilization showed that mitfa-deficiency is sufficient to up-regulate pigment progenitor and neural crest markers, while GNAQQ209L expression promotes a proliferative phenotype that is further enhanced by YAPS127A;S381A co-expression. Finally, we show that this oncogene-induced proliferative phenotype can be used to screen chemical inhibitors for their efficacy against the UM pathway. Overall, this study establishes that a neural crest signature correlates with poor UM survival, and describes an in vivo assay for preclinical trials of potential UM therapeutics.

Characterization of Uveal Melanoma Cell Lines and Primary Tumor Samples in 3D Culture.

Purpose: Uveal melanoma (UM) typically spreads to the liver, where it is incurable, as there are limited therapeutic interventions available. This study aimed to standardize laboratory methods for generating three-dimensional (3D) spheroids using UM cell lines and primary UM (PUM) samples for use in drug screening. Methods: Six UM cell lines and nine PUM, of differing genetic characteristics were cultured in two dimensions (2D) and three dimensions. 3D spheroid formation and growth were time monitored, and ImageJ software was used to calculate cross-sectional areas. PUM spheroids underwent immunohistochemistry for melanoma markers, nuclear BAP1, and cell proliferation. Chromosomal alterations in patient UM biopsies were compared with the corresponding 3D spheroid. In vitro drug assays testing doxorubicin and selumetinib assessed drug penetration and toxicity after 48 hours using imaging and the CellTiter-Glo 3D Cell Viability Assay. Results: All six UM cell lines formed spheroids of varying sizes and compactness; six of the nine PUM samples (67%) also formed spheroids, composed of MelanA+ proliferating melanocytes and admixed macrophages. PUM spheroids were genetically identical to the original sampled tumor. In vitro drug assays showed varying penetrations into UM cell line spheroids, with doxorubicin passing into the spheroid core and selumetinib having an effect largely on peripheral cells. Both drugs caused a dose-dependent reduction in viability of 3D spheroid cells. Conclusions: UM cell lines and PUM samples can successfully generate uniform 3D spheroids. PUM spheroids retain histological and genetic characteristics of the primary tumor. 3D spheroids are an important system for use in future high-throughput drug testing. Translational Relevance: The use of 3D spheroids allows early-phase drug screening and is an important first step toward treatment personalization for UM patients.

Novel red fluorescence protein based microplate assay for drug screening against dormant Mycobacterium tuberculosis by using paraffin.

The hypoxia model of dormancy is widely used in drug screening programs to identify novel inhibitors against latent Mycobacterium tuberculosis disease. In earlier reported microplate assays, hypoxia was maintained by either sealing the microplate or shifting in an anaerobic chamber to develop dormant phenotype. In these assays, inhibitors were added during inoculation, which mainly represents the active stage inhibitors instead of the dormant ones. Herein, the culture was covered with paraffin to develop hypoxia condition and consequently providing the advantage of adding compounds at any stage during incubation of 96-well plate. The stable expression of the red fluorescent protein in the bacilli under both actively growing as well as dormant conditions also facilitate the reliable estimation of growth and inhibition kinetics of bacilli in medium. Furthermore, S/N ratio and Z' factor of this assay were found to be > 27 and 0.91-0.94 respectively, which confirm the robustness of the protocol. This newly developed drug-screening assay offers an easy, inexpensive, safe and high throughput-screening tool to search novel antitubercular inhibitors against both active and dormant bacilli. The red fluorescent H37Ra strain is a suitable surrogate for the more virulent H37Rv strain, and thus this effort will help in combating latent tuberculosis.

Studies of RNA Sequence and Structure Using Nanopores.

Nanopores are powerful single-molecule sensors with nanometer scale dimensions suitable for detection, quantification, and characterization of nucleic acids and proteins. Beyond sequencing applications, both biological and solid-state nanopores hold great promise as tools for studying the biophysical properties of RNA. In this review, we highlight selected landmark nanopore studies with regards to RNA sequencing, microRNA detection, RNA/ligand interactions, and RNA structural/conformational analysis.

Progress and perspective of silkworm as a model of human diseases for drug screening / 药学学报

As a typical representative of Lepidopteran insects, the silkworm, Bombyx mori, has numerous advantages, such as simple husbandry, highly prolific nature, short generation time, easily handled to be operated with moderate body size, clear genetic background and abundant mutation resources. Silkworm has not only been studied by the geneticists, but also been used as a new laboratory animal model of human disease and drug screening. There is a plenty of genetic resources in silkworm, some of which could be used as models of human genetic diseases, such as Phenylketonuria, Parkinson 's disease, Hermansky-Pudlak syndrome and so on. Silkworm has also played a significant role in the study of pathogenesis of human pathogenic microorganisms. Moreover, silkworm could be used to evaluate the pharmacokinetic/pharmacodynamics properties and safety of a new drug comprehensively and systematically. At the same time, it can be used in the high throughput drug screening assays to shorten the period of the new drug research and development. This review summarizes that the silkworm is an excellent model in the drug screening assays, and has a potential in application to the large-scale drug screening.

Using yeast to model calcium-related diseases: example of the Hailey-Hailey disease.

Cross-complementation studies offer the possibility to overcome limitations imposed by the inherent complexity of multicellular organisms in the study of human diseases, by taking advantage of simpler model organisms like the budding yeast Saccharomyces cerevisiae. This review deals with, (1) the use of S. cerevisiae as a model organism to study human diseases, (2) yeast-based screening systems for the detection of disease modifiers, (3) Hailey-Hailey as an example of a calcium-related disease, and (4) the presentation of a yeast-based model to search for chemical modifiers of Hailey-Hailey disease. The preliminary experimental data presented and discussed here show that it is possible to use yeast as a model system for Hailey-Hailey disease and suggest that in all likelihood, yeast has the potential to reveal candidate drugs for the treatment of this disorder. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.

Validation of a modified fluorimetric assay for the screening of trichomonacidal drugs

A fluorimetric microassay that uses a redox dye to determine the viability of the flagellate Trichomonas vaginalis has been optimised to provide a more sensitive method to evaluate potential trichomonacidal compounds. Resazurin has been used in recent years to test drugs against different parasites, including trichomonadid protozoa; however, the reproducibility of these resazurin-based methods in our laboratory has been limited because the flagellate culture medium spontaneously reduces the resazurin. The objective of this work was to refine the fluorimetric microassay method previously developed by other research groups to reduce the fluorescence background generated by the media and increase the sensitivity of the screening assay. The experimental conditions, time of incubation, resazurin concentration and media used in the microtitre plates were adjusted. Different drug sensitivity studies against T. vaginalis were developed using the 5-nitroimidazole reference drugs, new 5-nitroindazolinones and 5-nitroindazole synthetic derivatives. Haemocytometer count results were compared with the resazurin assay using a 10% solution of 3 mM resazurin dissolved in phosphate buffered saline with glucose (1 mg/mL). The fluorimetric assay and the haemocytometer counts resulted in similar percentages of trichomonacidal activity in all the experiments, demonstrating that the fluorimetric microtitre assay has the necessary accuracy for high-throughput screening of new drugs against T. vaginalis.

The effect of brucine on hepatocellular carcinoma cell lines in vitro / 中华普通外科杂志

Objective To study the effect of brucine on the growth of a hepatocellular carcinoma cell line in vitro. Methods Brucine was added into a liver cancer cell line of SMMC-7721 in vitro, at drug concentration of brucine from 2. 5 μg/ml to 400 μg/ml. The inhibition rate of cell growth was measured by MTT technique after the cells were cultured for 72 hours. The protein and mRNA expression of PCNA,cyclin D1 and FAS were respectively assayed with Western blotting and fluorescent quantitation RT-PCR techniques at 24, 48, 72 h. Results The inhibition rate of liver cancer cell was near 100% when the brucine concentration was at 320 μg/ml. The protein and mRNA expression of FAS were of no significant difference at 24 h vs 48 h ( seperately F = 2. 547,1. 582, all P ＞ 0. 05 ), and significant difference existed at 24 h vs 72 h( seperately F = 1. 036, 1. 137, all P ＜ 0. 05 ). The protein and mRNA expression of PCNA,Cyclin D1 were of no significant difference between various time period( seperately PCNA F = 3.612,2. 174,3.029;Cyclin D1 F=2.361,2.915,1.976,all P＞0.05). Conclusions Brucine inhibits the growth of liver cancer cells, by inducing increased apoptosis of the cells probably through FAS overexpression.

Heterogeneous Chemosensitivity of Breast Cancer Determined by Adeonsine Triphosphate Based Chemotherapy Response Assay / 한국유방암학회지

PURPOSE: Breast cancer is heterogeneous disease and the response to chemotherapeutic agents is also heterogeneous from patient to patient. Chemotherapy response assay is in vitro test that is performed to evaluate the degree of tumor growth inhibition by chemotherapy drugs. In this study, we performed the chemotherapy response assay using adenosine triphosphate (ATP-CRA) in breast cancer patients and assessed the clinical availability. METHODS: Sixty five breast cancer patients were enrolled in this study. Cancer cells were evenly divided and treated with commonly used chemotherapeutic drugs in breast cancer (doxorubicin, epirubicin, 5-fluorouracil, paclitaxel, docetaxel, vinorelbine, and gemcitabine). To verify in vitro ATP-CRA indirectly, we analyzed the correlation between cell death rate (CDR) of doxorubicin and epirubicin, and between doxorubicin and paclitaxel. We also analyzed the mean CDR of doxorubicin, epirubicin and paclitaxel by HER2 status. RESULTS: We could successfully perform the ATP-CRA in 60 patients (95.2%). In all cases, we can get the results within 7 days. The range of CDR was very wide, from 0 to more than 50%, except gemcitabine. Epirubicin showed the highest mean CDR (39.9%) and doxorubicin, paclitaxel in order. According to the chemosensitivity index, paclitaxel is the most frequently first-ranked and doxorubicin, epirubicin in order. Correlation coefficient between the cell death rate of doxorubicin and epirubicin is 0.4210 and 0.1299 between paclitaxel and doxorubicin. In HER2 positive group, mean CDR of paclitaxel, epirubicin and doxorubicin was higher than in HER2 negative group, even though epirubicin and doxorubicin were not statistically significant (p=0.018, p=0.114, p=0.311, respectively). CONCLUSION: ATP-CRA showed heterogeneous results in individual patients. ATP-CRA was successful and can be performed within short time period. According to our in vitro study, it showed similar results with in vivo study but for the clinical use, the prospective randomized controlled trial should be preceded.

Application of ATP-TCA in clinic / 国际肿瘤学杂志

ATP-tumor chemosensitivity assay(ATP-TCA)is a tumor chemosensitivity assay in vitro.Beacause of the special merites of A11P-TCA,it is seemed to be the most promising and effective method of tumor chemosensitivity in vitro.Application of ATP-TCA in clinic has got significant effects.ATP-TCA is a good method for individualized chemotherapy.

Collagen gel droplet-embedded culture drug-sensitivity test and potential for personalizing cancer treatment.

Sensitivity testing for general anticancer agents involves culturing cancer cells, exposure to an anticancer agent, and assessing the degree of growth inhibition. One such method is the collagen gel droplet-embedded culture drug-sensitivity test (CD-DST). Clinical results confirm a close correlation of a better than 75% accuracy between CD-DST results and responses to anticancer agents administered in the clinical setting. Although there have been few randomized, controlled studies of the CD-DST method, the general observation is that cancer patients survive longer if their disease responds to an anticancer agent than if it is ineffective. Therefore, it can be extrapolated that the high diagnostic accuracy of CD-DST is indirect evidence that this method can be used to select the group for whom chemotherapy will be effective, with a resultant prolongation of their survival time, and the group for whom chemotherapy will be ineffective, with no increased survival time.

Chemosensitivity testing for human gastric cancer with short-term culture cells vs purified primary culture cells using the MTT assay / 中国癌症杂志

Purpose:To evaluate the feasibility, advantages and disadvantages of chemosensitivity test of human gastric cancer using MTT assay with short term culture tumor cells contaminated by nonmalignant cells compared with purifiedly primary culture tumor cells.Methods:Fifty nine fresh samples from patients with gastric cancer were obtained from operating rooms. Chemosensitivity results were provided by the MTT assay with short term culture cells. The primary culture cells were purified by means of a series of methods such as repeated cell attachment, differential trypsinization and natural purification which removed fibroblasts and other nonmalignant cells. The same MTT assay was conducted using purified cells. Chemosensitivity results between short term method and purification method were compared for seven antitumor drugs. Results:The success rate of short term method using the MTT assay for chemosensitivity testing was 81 4% (48 of 59 patients),and for the purification method it was 50.8(30 of 59 patients). The average was 20.2?9.5 days when primary cells were cultured into purified cancer cells. The optical density ( A ) value correlated directly with the the number of tumor cells with the two methods( P

Relationship between the sensitivity of human colon carcinoma cells to gefitinib and the expressions of Akt and MAPK / 解放军医学杂志

Objective To investigate the relationship between the sensitivity of colon carcinoma cells to epidermal growth factor receptor(EGFR) inhibitor,gefitinib,and the downstream proteins of EGFR.Methods The expressions of EGFR proteins of 6 colon carcinoma cell lines(Lovo,HCT116,HT29,LS174T,SW480 and SW620) were determined with immunocytochemistry staining.The inhibitory effects of gefitinib on the growth of colon carcinoma cells were assessed by MTT,and the expression levels of Akt and MAPK as well as their phosphorylated forms(p-Akt and p-MAPK) were assessed by Western blotting.Results EGFR protein expressed in all the Lovo,HCT116,HT29,LS174T and SW480 cells,and the highest expression was found in Lovo cells,but not in SW620 cells.Lovo cells showed the highest,HT29 and SW480 cells showed moderate,sensitivity to gefitinib,while the others showed more or less resistance to gefitinib.No significant difference was found between the growth inhibition and IC50 values among the 6 cell lines despite of being treated with fetal bovine serum or EGF.Akt protein existed in all the cell lines without notable difference.Lovo and SW620 cells showed the least of p-Akt expression(P

Relationship between antitumor activity of Gefitinib and epidermal growth factor receptor expression in human colorectal cancer cell lines / 解放军医学杂志

Objective To investigate the antitumor activity of Gefitinib, a selected epidermal growth factor receptor-tyrosine kinase inhibitor, on human colorectal cancer cell lines in vitro, and to explore the relationship between the inhibitory effect of Gefitinib on cancer cells and the expression of epidermal growth factor receptor (EGFR). Methods The growth inhibitory effects of Gefitinib, which expressed as the half growth inhibition dose IC50, on colorectal cancer cells were assessed by MTT assay. EGFR mRNA expression was detected by reverse transcriptional PCR (RT-PCR). Western blot was used to determine the expression of EGFR protein as well as its phosphorylated forms (p-EGFR). Results Gefitinib inhibited growth of all the six colorectal cancer cell lines in vitro with an IC50 range from 6.5 to 172.7?mol/L. Lovo cell line, with an IC50 value less than 10?mol/L, was the most sensitive one to Gefitinib, HT29 and SW480 were moderate sensitive to 10?mol/L