Cell cycle analysis using flow cytometry (FC) to measure cellular DNA content is a common procedure in drug mechanism of action studies. Although this technique lends itself readily to cell lines that grow in suspension, adherent cell cultures must be resuspended in a cumbersome and potentially invasive procedure that normally involves trypsinization and mechanical agitation of monolayer cultures. High-content analysis (HCA), an automated microscopy-based technology, is well suited to analysis of monolayer cell cultures but provides intrinsically less accurate determination of cellular DNA content than does FC and thus is not the method of choice for cell cycle analysis. Using Cellomics’s ArrayScan™ reader, the authors have developed a 4-color multiparametric HCA approach for cell cycle analysis of adherent cells based on detection of DNA content (4,6-diamidino-2-phenylindole [DAPI] fluorescence), together with the known cell cycle markers bromo-2-deoxyuridine (BrdU) incorporation, cyclin B1 expression, and histone H3 (Ser28) phosphorylation within a single cell population. Considering all 4 markers together, a reliable and accurate quantification of cell cycle phases was possible, as compared with flow cytometric analysis. Using this assay, specific cell cycle blocks induced by treatment with thymidine, paclitaxel, or nocodazole as test drugs were easily monitored in adherent cultures of U-2 OS osteosarcoma cells.

Identification of thyroid tumor cell vulnerabilities through a siRNA-based functional screening

Background: High-content screening (HCS) defines a series of cell-based multiparametric approaches for analysis at the single-cell level. In recent years, HCS has been increasingly pursued in the drug discovery field, adding to the repertoire of assay type, or increasing throughput in applications such as compound screening and mechanism of action studies, as well as for target identification/validation (siRNA screening). Obviously, as cells represent the objects of high-content assays, the outcome of any HCS assay is determined by the cell type: the choice of the most suitable cellular model for a given assay is a critical step that must follow biological and technical criteria. Method: Here, I discuss these criteria and report a systematic survey of cell types used so far in HCS, with particular emphasis on their strengths and drawbacks. I also illustrate my expectations for future advances on cellular models used in HCS. Conclusion: Despite the plethora of cell types potentially suitable for HCS, so fa...

HER-3 is becoming an attractive target for antibody–drug conjugate (ADC)-based therapy. Indeed, this receptor and its ligands are found to be overexpressed in several malignancies, and re-activation of its downstream signaling axis is known to play a critical role in modulating the sensitivity of targeted therapeutics in different tumors. In this study, we generated a novel ADC named EV20/NMS-P945 by coupling the anti-HER-3 antibody EV20 with a duocarmycin-like derivative, the thienoindole (TEI) NMS-P528, a DNA minor groove alkylating agent through a peptidic cleavable linker. This ADC showed target-dependent cytotoxic activity in vitro on several tumor cell lines and therapeutic activity in mouse xenograft tumor models, including those originating from pancreatic, prostatic, head and neck, gastric and ovarian cancer cells and melanoma. Pharmacokinetics and toxicological studies in monkeys demonstrated that this ADC possesses a favorable terminal half-life and stability and it is well tolerated. These data support further EV20/NMS-P945 clinical development as a therapeutic agent against HER-3-expressing malignancies.

The discovery of agents which disrupt cancer cell division by specifically targeting key components of the cell-cycle machinery represents a major focus of recent drug discovery efforts in Oncology. The drug discovery process can be greatly enhanced by multiparametric cellular analysis which can assist in confirmation, often in a few multiplexed assays, of the mechanism of action (MOA) of compounds identified through biochemical screening or similar in vitro methods. High-Content Analysis (HCA) is a technique based on automated microscopy which enables multiparametric analysis of fluorescent indicators to define cellular responses to compound treatment. Several distinct fluorescence channels can be acquired and analyzed within a single measure in the same cell population. Here we present a multiparametric HCA approach to characterize potential cell-cycle inhibitors in osteosarcoma U-2 OS adherent cell cultures. This approach allows monitoring of compound-induced cell-cycle perturbations by analyzing specific cellular markers such as nuclear morphology, DNA content or histone H3 phosphorylation. Moreover, the induction of DNA damage response or apoptosis can also be readily evaluated. By considering the profile of the investigated cellular markers at different compound concentrations, a fingerprint defines the cellular and molecular phenotype associated with each compound.

Abstract: High-content analysis (HCA) is a term used to describe techniques involving multiplexed analysis of fluorescent markers to measure multiple cellular responses to biological stimuli or drug treatment. HCA is usually based on automated microscopy or related technologies, and its value lies in providing multiparametric information on single cells within a population. During the last decade, several HCA approaches have been developed and applied to assess cellular mechanism of action of pharmacologically relevant compounds identified through biochemical screening or similar in vitro methods. With automation and instrument development, these approaches have evolved to the extent that the technique is now routinely used in screening applications, including primary HTS on compound collections. Here, we review the field and discuss in particular the application of HCA to the discovery of small molecule inhibitors targeting kinases which are implicated in Oncology.