Publications (4)21.68 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Two issues are critical to the development of effective cancer-drug combinations. First, it is necessary to determine common combinations of alterations that exert strong control over proliferation and survival regulation for the general type of cancer being considered. Second, it is necessary to have a drug testing method that allows one to assess the variety of responses that can be provoked by drugs acting at key points in the cellular processes dictating proliferation and survival. Utilizing a previously reported GFP (green fluorescent protein) reporter-based technology that provides dynamic measurements of individual reporters in individual cells, the present paper proposes a dynamical systems approach to these issues. It involves a three-state experimental design: (1) formulate an oncologic pathway model of relevant processes; (2) perturb the pathways with the test drug and drugs with known effects on components of the pathways of interest; and (3) measure process activity indicators at various points on cell populations. This design addresses the fundamental problems in the design and analysis of combinatorial drug treatments. We apply the dynamical approach to three issues in the context of colon cancer cell lines: (1) identification of cell subpopulations possessing differing degrees of drug sensitivity; (2) the consequences of different drug dosing strategies on cellular processes; and (3) assessing the consequences of combinatorial versus monotherapy. Finally, we illustrate how the dynamical systems approach leads to a mechanistic hypothesis in the colon cancer HCT116 cell line.
- [Show abstract] [Hide abstract] ABSTRACT: High-content cell imaging based on fluorescent protein reporters has recently been used to track the transcriptional activities of multiple genes under different external stimuli for extended periods. This technology enhances our ability to discover treatment-induced regulatory mechanisms, temporally order their onsets and recognize their relationships. To fully realize these possibilities and explore their potential in biological and pharmaceutical applications, we introduce a new data processing procedure to extract information about the dynamics of cell processes based on this technology. The proposed procedure contains two parts: (1) image processing, where the fluorescent images are processed to identify individual cells and allow their transcriptional activity levels to be quantified; and (2) data representation, where the extracted time course data are summarized and represented in a way that facilitates efficient evaluation. Experiments show that the proposed procedure achieves fast and robust image segmentation with sufficient accuracy. The extracted cellular dynamics are highly reproducible and sensitive enough to detect subtle activity differences and identify mechanisms responding to selected perturbations. This method should be able to help biologists identify the alterations of cellular mechanisms that allow drug candidates to change cell behavior and thereby improve the efficiency of drug discovery and treatment design.
- [Show abstract] [Hide abstract] ABSTRACT: Genomic technologies, such as array comparative genomic hybridization (aCGH), increasingly offer definitive gene dosage profiles in clinical samples. Historically, copy number profiling was limited to large fresh-frozen tumors where intact DNA could be readily extracted. Genomic analyses of pre-neoplastic tumors and diagnostic biopsies are often limited to DNA processed by formalin-fixation and paraffin-embedding (FFPE). We present specialized protocols for DNA extraction and processing from FFPE tissues utilizing DNase processing to generate randomly fragmented DNA. The protocols are applied to FFPE clinical samples of varied tumor types, from multiple institutions and of varied block age. Direct comparative analyses with regression coefficient were calculated on split-sample (portion fresh/portion FFPE) of colorectal tumor samples. We show equal detection of a homozygous loss of SMAD4 at the exon-level in the SW480 cell line and gene-specific alterations in the split tumor samples. aCGH application to a set of archival FFPE samples of skin squamous cell carcinomas detected a novel hemizygous deletion in INPP5A on 10q26.3. Finally we present data on derivative of log ratio, a particular sensitive detector of measurement variance, for 216 sequential hybridizations to assess protocol reliability over a wide range of FFPE samples.