Cell migration assay

a cell migration and assay technology, applied in the field of assays, can solve the problems of slow discovery and development, inability to identify all clinically important molecules in conventional drug discovery formats for chemoattractant receptor antagonists, and inability to distinguish genuine antagonists

Inactive Publication Date: 2005-08-25
CHEMOCENTRYX INC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Considerable effort is then required to distinguish the genuine antagonists from those compounds or molecules that caused false positive signals.
Because of this separation of physical interaction (ligand-receptor binding) from function (receptor signaling and downstream events), false positive signals are often observed, slowing discovery and development.
Small molecules that initially appear to be inhibitors of receptor-ligand binding interactions (a desired result) may give such a result, for example, either by inhibiting the receptor-ligand interaction by binding the target receptor or ligand (desirable reasons), or by sickening or killing cells, or wielding other undefined effects (undesirable reasons).
Furthermore, conventional drug discovery formats for chemoattractant receptor antagonists fail to identify all clinically important molecules, a consequence of false negative signals.
While defending the individual from invading pathogens and tumors, the immune system can cause disease when improperly regulated.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Determining Inhibitory Concentration of SDF (CXCR4)

[0067] To obtain a dose response curve for activated lymphocytes expressing cell surface CXCR4, a conventional cell migration assay was used (Bacon et al., 1988; Penfold et al., 1999). Cells were harvested by centrifugation and then resuspended in cell migration buffer (Hank's balanced salt solution (HBSS) / 0.1% bovine serum albumin (BSA) at 2.5×106 cells / ml. The CXCR4 ligand stromal-derived factor (SDF-1) was prepared in a concentration series (0.1 nM to 10 mM) by serial dilution in cell migration buffer. At low concentrations, SDF activates cell migration of CXCR4-bearing activated lymphocytes.

[0068] SDF ligand was loaded in the bottom chamber of a ChemoTx® cell migration apparatus (5 μm pore polycarbonate polyvinylpyrrolidone-coated filters (Neuroprobe; Gaithersburg, Md.); 29 μl / well) and 20 μl of cell suspension was placed in the upper chamber. The cells were incubated at 37° C. for 150 minutes. The assay was terminated by remo...

example 2

Validation of the RAM Assay Using a Viral Polypeptide Antagonist of CXCR4

[0070] In the RAM assay, antagonists of chemokine receptors are identified by their ability to activate migration of cells that are incubated with inhibitory chemokine concentrations. To validate the RAM assay, the viral chemokine, vMIP-II, was used as a CXCR4 antagonist. vMIP-II binds with high affinity to CXCR4, blocking receptor signaling and inhibiting cell migration, competing with CXCR4's usual ligand, SDF (Kledal et al., 1997). If CXCR4 expressing cells that are immobilized by inhibitory concentrations of SDF are activated to migrate in the presence of vMIP-II with increased migration, this result would verify the RAM assay principle. For reference and as a control, a conventional cell migration assay was performed. In the conventional assay format, cell migration is inhibited by vMIP-II.

[0071] Cell migration was measured using the two formats with the corresponding amounts of SDF chemokine: [0072] (1)...

example 3

Validation of RAM Assay Using Known Small Molecule Antagonists of CXCR3, CXCR4 and CCR1

[0076] RAM assays were performed as described in Example 2, except previously identified small molecule antagonists instead of vMIP-II were used, as well as additional cell types as described in Table 2.

TABLE 2Experimental variablesAntagonist1ReceptorLigand(s)CellsRAMAG-1CXCR3I-TAC (250 nM),activated humanIP-10lymphocytesRAMAG-2CXCR4SDF-1CXCR4-expressingMOLT-4 cells (human Tlymphoblast; AmericanType Tissue Collection(ATCC); Manassas, VA)RAMAG-3CCR1MIP-1αTHP-1 cells (humanmonocytic; ATCC)

1As defined using a conventional cell migration assay and further independently confirmed.

2Inhibitory concentrations determined as in Example 1.

[0077] In the RAM assay, activated lymphocytes incubated in the presence of increasing concentrations of RAMAG-1 and the CXCR3 ligand I-TAC at 250 nM, cell migration was activated at less than 1 μM (FIG. 6A); as RAMAG-1 concentration increased, migration increased, rea...

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Abstract

The present invention is directed to a modified cell migration assay allowing for improved identification and discrimination of chemokine receptor antagonists from non-specific blockers.

Description

RELATED APPLICATIONS [0001] This application claims priority to U.S. provisional application Ser. No. 60 / 296,682 filed Jun. 7, 2001, which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention is directed to an assay for identifying antagonists of chemoattractant receptors, such as chemokine receptors. One advantage of the assay compared with prior assays is its ability to discriminate valid chemoattractant receptor antagonists from those compounds that generate false positive and negative signals. BACKGROUND [0003] High-throughput screening (HTS) methods for identifying antagonists of chemoattractant receptors often rely on detecting perturbations in downstream events, such as cell migration. In the case of chemokine receptors, leukocyte cell migration is often assayed. However, compounds disrupting cell membranes or blocking downstream events mimic these outcomes, masquerading as candidate antagonists. Considerable effort is then r...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C12Q1/02G01N33/15G01N33/50G01N33/68
CPCG01N33/5008G01N33/5029G01N2500/00G01N2333/715G01N2500/04G01N33/6863G01N33/567
Inventor WEI, ZHENGMIAO, ZHENHUA
Owner CHEMOCENTRYX INC
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