kinase-inhibitor-screening-in-self-assembled-human-protein-microarrays

Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays

The screening of kinase inhibitors is crucial for better understanding properties of a drug and for the identification of potentially new targets with ...

Arizona State University

Pennsylvania State University

Proteomics aspires to elucidate the functions of all proteins. Protein microarrays provide an important step by enabling high-throughput studies of displayed proteins. However, many functional assays of proteins include untethered intermediates or products, which could frustrate the use of planar arrays at very high densities because of diffusion to neighboring features. The nucleic acid programmable protein array (NAPPA) is a robust in situ synthesis method for producing functional proteins just-in-time, which includes steps with diffusible intermediates. We determined that diffusion of expressed proteins led to cross-binding at neighboring spots at very high densities with reduced interspot spacing. To address this limitation, we have developed an innovative platform using photolithographically etched discrete silicon nanowells and used NAPPA as a test case. This arrested protein diffusion and cross-binding. We present confined high density protein expression and display, as well as functional protein-protein interactions, in 8000 nanowell arrays. This is the highest density of individual proteins in nanovessels demonstrated on a single slide. We further present proof of principle results on ultrahigh density protein arrays capable of up to 24000 nanowells on a single slide.

High density diffusion-free nanowell arrays.

We aim to develop a protein microarray platform capable of presenting both natural and denatured forms of proteins for antibody biomarker discovery. We will further optimize plasma screening protocols to improve detection.

A versatile protein microarray platform enabling antibody profiling against denatured proteins.

In vitro transcription/translation (IVTT) systems are widely used in proteomics. For clinical applications, mammalian systems are preferred for protein folding and activity; however, the level of protein obtained is low. A new system extracted from human cells (1-Step Human Coupled IVT (HCIVT)) has the potential to overcome this problem and deliver high yields of protein expressed in a human milieu.

Robust microarray production of freshly expressed proteins in a human milieu.

The study of protein function usually requires the use of a cloned version of the gene for protein expression and functional assays. This strategy is particularly important when the information available regarding function is limited. The functional characterization of the thousands of newly identified proteins revealed by genomics requires faster methods than traditional single-gene experiments, creating the need for fast, flexible, and reliable cloning systems. These collections of ORF clones can be coupled with high-throughput proteomics platforms, such as protein microarrays and cell-based assays, to answer biological questions. In this tutorial, we provide the background for DNA cloning, discuss the major high-throughput cloning systems (Gateway® Technology, Flexi® Vector Systems, and Creator(TM) DNA Cloning System) and compare them side-by-side. We also report an example of high-throughput cloning study and its application in functional proteomics. This tutorial is part of the International Proteomics Tutorial Programme (IPTP12).

High-throughput cloning and expression library creation for functional proteomics.

We report on a quantitative study of small molecule binding kinetics on protein microarrays with plasmonic-based electrochemical impedance microscopy (P-EIM). P-EIM measures electrical impedance optically with high spatial resolution by converting a surface charge change to a surface plasmon resonance (SPR) image intensity change, and the signal is not scaled to the mass of the analyte. Using P-EIM, we measured binding kinetics and affinity between small molecule drugs (imatinib and SB202190) and their target proteins (kinases Abl1 and p38-α). The measured affinity values are consistent with reported values measured by an indirect competitive binding assay. We also found that SB202190 has weak bindings to ABL1 with KD > 10 μM, which is not reported in the literature. Furthermore, we found that P-EIM is less prone to nonspecific binding, a long-standing issue in SPR. Our results show that P-EIM is a novel method for high-throughput measurement of small molecule binding kinetics and affinity, which is critical to the understanding of small molecules in biological systems and discovery of small molecule drugs. 

Measurement of small molecule binding kinetics on a protein microarray by plasmonic-based electrochemical impedance imaging.

Alterations in ERBB family members have been associated with many tumor malignancies. EGFR and ERBB2 have been extensively explored in clinical oncology and several drugs currently target them therapeutically. However, the significance of ERBB4 as a potential therapeutic target remains mostly unexplored, even though ERBB4 is overexpressed or mutated in many solid tumors. Using a unique functional protein microarray platform, we found that ibrutinib inhibits ERBB4 activity in the same nM range as its canonical target, BTK. Cell-based assays revealed that ibrutinib treatment inhibited cell growth and decreased phosphorylation of ERBB4 and downstream targets MEK and ERK in cancer cell lines with high levels of endogenous ERBB4. In vivo, ibrutinib-responsive mouse xenograft tumors showed decreased tumor volumes with ibrutinib treatment. Interestingly, global gene expression comparisons between responsive and non-responsive cells identified a signature featuring the WNT pathway that predicts growth responsiveness to ibrutinib. Non-responsive ERBB4-expressing cell lines featured elevated activity of the WNT pathway, through the overexpression of WNT5A. Moreover, inhibition of WNT5A expression led to an ibrutinib response in non-responsive cell lines. Our data show that inhibiting ERBB4 reduces cell growth in cells that have low WNT5A expression and reveal a link between the ERBB4 and WNT pathways.

Fernanda Festa

Virginia G. Piper Center for Personalized Diagnostics,
Biodesign Institute,
Virginia G. Piper Center for Personalized Diagnostics, Biodesign Institute

Arizona State University

Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays

Fernanda Festa

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Arizona State University

Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays

Virginia G. Piper Center for Personalized Diagnostics,
Biodesign Institute,
Virginia G. Piper Center for Personalized Diagnostics, Biodesign Institute