PAIN-less identification and evaluation of small molecule inhibitors against protein tyrosine phosphatase 1B

Synthesis of small peptide compounds, molecular docking, and inhibitory activity evaluation against phosphatases PTP1B and SHP2

Background

The protein tyrosine phosphatases PTP1B and SHP2 are promising drug targets in treatment design for breast cancer. Searching for specific inhibitors of their activity has recently become the challenge of many studies. Previous work has indicated that the promising PTP inhibitors may be small compounds that are able to bind and interact with amino residues from the binding site.

Purpose

The main goal of our study was to synthesize and analyze the effect of selected small peptide inhibitors on oncogenic PTP1B and SHP2 enzymatic activity and viability of MCF7 breast cancer cells. We also performed computational analysis of peptides binding with allosteric sites of PTP1B and SHP2 phosphatases.

Methods

We measured the inhibitory activity of compounds utilizing recombinant enzymes and MCF7 cell line. Computational analysis involved docking studies of binding conformation and interactions of inhibitors with allosteric sites of phosphatases.

Results

The results showed that the tested compounds decrease the enzymatic activity of phosphatases PTP1B and SHP2 with IC₅₀ values in micromolar ranges. We observed higher inhibitory activity of dipeptides than tripeptides. Phe-Asp was the most effective against SHP2 enzymatic activity, with IC₅₀=5.2±0.4 µM. Micromolar concentrations of tested dipeptides also decreased the viability of MCF7 breast cancer cells, with higher inhibitory activity observed for the Phe-Asp peptide. Moreover, the peptides tested were able to bind and interact with allosteric sites of PTP1B and SHP2 phosphatases.

Conclusion

Our research showed that small peptide compounds can be considered for the design of specific inhibitors of oncogenic protein tyrosine phosphatases.

Polymerase assays for lead discovery: An overall review of methodologies and approaches

Polymerases represent an attractive molecular target for antibacterial drug development, antiviral intervention and cancer therapy. Over the past decade, academic groups and scientists from pharmaceutical industry have developed a large plethora of different functional assays to monitor the enzymatic reaction catalyzed by polymerases. These assays were used to enable high-throughput screening (HTS) for lead discovery purposes, as well as hit-to-lead (H2L) drug profiling activities. In both cases the choice of the assay technology is critical and to the best of our knowledge, there is no review available to help scientists to choose the most suitable assay. This review summarizes the most common functional assays developed to monitor the enzymatic activity of polymerases and discusses the advantages and disadvantages of each assay. Assays are presented and evaluated in term of cost, ease of use, high-throughput screening compatibility and liability towards delivering false positives and false negatives.

Reviewing Hit Discovery Literature for Difficult Targets: Glutathione Transferase Omega-1 as an Example

Early stage drug discovery reporting on relatively new or difficult targets is often associated with insufficient hit triage. Literature reviews of such targets seldom delve into the detail required to critically analyze the associated screening hits reported. Here we take the enzyme glutathione transferase omega-1 (GSTO1-1) as an example of a relatively difficult target and review the associated literature involving small-molecule inhibitors. As part of this process we deliberately pay closer-than-usual attention to assay interference and hit quality aspects. We believe this Perspective will be a useful guide for future development of GSTO1-1 inhibitors, as well serving as a template for future review formats of new or difficult targets.