Kam's lab
Classical drug development is based on definition of a molecular target (an enzyme, receptor etc) involved in processes related to a malfunction, and search for compounds that bind to the target and modulates its activity. Often compounds which affect the target molecule activity fail to function in the living cell or in the whole organism. We apply an alternative approach to facilitate drug development, focusing directly on cell functions relevant to the disease state, rather than to a suspect molecule. This approach is not only bypassing target definition, which may be a hard or impossible task for multifunctional disorders characterization of many diseases, but allows to better select for potential drugs which are effective at the whole system level.
The ability to test compounds and evaluate functional effects on cells became possible via new developments in quantitative, multi-dimensional light microscopy, allowing examination of live cells under controlled, close to physiological condition. Genetic tools make light microscopy capable of reporting about multiple molecules simultaneously, as well as about many structural and dynamic parameters relevant to cell responses and their proliferation, all at high three-dimensional spatial and temporal resolution.
We study in these screens cell adherence and the associated actin cytoskeletal network. These are of great interest for the following reasons:
Cell adherence mechanisms are of great basic importance in cell and tissue physiology, and are both targets and sources of cellular signaling.
Their typical cellular patterns makes then a rich and sensitive reporter to perturbations in a way that highlights their molecular structural dynamics.
They are crucial for cell anchorage that is perturbed in cancer causing metastasis, glaucoma, etc.
We are using our high-resolution cell-based screening microscope platform to identify cytoskeleton-affecting compounds from natural extracts library and from collections of small compounds. Recently we also launched an RNAi screen for effects of kinases and phosphatases on the cytoskeleton.
Our plan is to demonstrate that a cell-based approach to the design and optimization of multi-drug cocktails will be able to achieve high efficiency at lower individual drug concentrations (with the obvious reduction of side-effects). We propose that multiple targeting of a network may not only be more efficient to affect its activity, but can also be optimized with selectivity to a specific cell types, with the far-aim of developing strategies for targeting malignant cells, and in general, developing methods for personalized medicine.
With this in mind, we plan to assemble a library of drugs with well characterized cellular effects, including over-the-counter drugs and compounds used in cell biological research. We shall characterize the drugs using quantitative image analysis for their effects on selected cellular properties. For example, cytoskeletal-disrupting drugs will be essayed using cells expressing GFP tagged cytoskeletal proteins, and fluorescent imaging of the cytoskeleton structures will establish quantitative essays.
Given the activities of each drug, we shall scan drug combinations, searching for synergistic or antagonistic pairs. Prior understanding of the mechanisms of action of each drug will allow rational selection of combinations, but the throughput of our system will also allow screening of all pairs of hundreds of drugs, including natural extracts. As a proof of principle for the concept of increased cell-specificity of drug cocktails compared to single drugs, we shall measure single and multiple-drug activities in several cell lines, searching for strong synergism for one cell line. The known differences in the organization and the control of cytoskeleton-related functions in various cell lines gives support to the proposed working hypothesis.
Reporter HelaJW cells stably expressing
Tubulin conjugated to mCherry.
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