Microarray TRAP—a high-throughput assay to quantitate telomerase activity

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

Natural compounds have diverse structures and are present in different forms of life. Metabolites such as tannins, anthocyanins, and alkaloids, among others, serve as a defense mechanism in live organisms and are undoubtedly compounds of interest for the food, cosmetic, and pharmaceutical industries. Plants, bacteria, and insects represent sources of biomolecules with diverse activities, which are in many cases poorly studied. To use these molecules for different applications, it is essential to know their structure, concentrations, and biological activity potential. In vitro techniques that evaluate the biological activity of the molecules of interest have been developed since the 1950s. Currently, different methodologies have emerged to overcome some of the limitations of these traditional techniques, mainly via reductions in time and costs. These emerging technologies continue to appear due to the urgent need to expand the analysis capacity of a growing number of reported biomolecules. This review presents an updated summary of the conventional and relevant methods to evaluate the natural compounds’ biological activity in vitro.

Advances in optical assays for detecting telomerase activity

Telomerase uses its RNA as template and its protein unit as reverse transcriptase to synthesize TTAGGG repeats at the ends of the eukaryotic chromosome to maintain the lengths of telomeres. Telomerase activity up-regulates in about 85% of human tumors compared with somatic cells, which indicates that telomerase is a tumor biomarker. Reliable assay of telomerase activity is thus essential in diagnosis and management of malignant tumors. In this review, recent developed optical assays are summarized based on the readout signal, including chemiluminescence assay, colorimetric assay, and fluorescence assay.

Guidelines for the selection of functional assays to evaluate the hallmarks of cancer

The hallmarks of cancer capture the most essential phenotypic characteristics of malignant transformation and progression. Although numerous factors involved in this multi-step process are still unknown to date, an ever-increasing number of mutated/altered candidate genes are being identified within large-scale cancer genomic projects. Therefore, investigators need to be aware of available and appropriate techniques capable of determining characteristic features of each hallmark. We review the methods tailored to experimental cancer researchers to evaluate cell proliferation, programmed cell death, replicative immortality, induction of angiogenesis, invasion and metastasis, genome instability, and reprogramming of energy metabolism. Selecting the ideal method is based on the investigator's goals, available equipment and also on financial constraints. Multiplexing strategies enable a more in-depth data collection from a single experiment - obtaining several results from a single procedure reduces variability and saves time and relative cost, leading to more robust conclusions compared to a single end point measurement. Each hallmark possesses characteristics that can be analyzed by immunoblot, RT-PCR, immunocytochemistry, immunoprecipitation, RNA microarray or RNA-seq. In general, flow cytometry, fluorescence microscopy, and multiwell readers are extremely versatile tools and, with proper sample preparation, allow the detection of a vast number of hallmark features. Finally, we also provide a list of hallmark-specific genes to be measured in transcriptome-level studies. Although our list is not exhaustive, we provide a snapshot of the most widely used methods, with an emphasis on methods enabling the simultaneous evaluation of multiple hallmark features.

A Simple Quartz Crystal Microbalance Nucleic Acid Sensor for Detection of Telomerase

A simple, fast, inexpensive sensitive/selective nucleic acid sensor based on the quartz crystal microbalance system (QCM) was developed for the detection of telomerase. A specially designed oligonucleotide probe, that is complementary to the template region of the telomerase enzyme, was immobilized onto the silver electrodes of piezoelectric crystals with polyethyleneimine adhesion cross-linked with glutaraldehyde. Optimum coating and immobilization conditions were determined. The QCM nucleic acid sensor was used for the detection of telomerase enzyme in human cervix carcinoma cell (HeLa) lysates. A significant difference between the telomerase negative cells (BHK) from HeLa cells, which was used for qualitative and quantitative detection of telomerase. An almost a linear correlation with the protein concentration was obtained with a R 2 value of 0.9621. The linear correlation coefficients (R2) for HeLa and BHK cell lysate obtained by applying Langmuir adsorption model, were 0.9630 and 0.9766, respectively. Telomerase activity was confirmed by stretch-PCR and fluorometric (F)-TRAP within HeLa extracts. The results obtained both with the QCM system developed in this study and F-TRAP method applied is significantly correlated (r = 0.968, p<0.001).