Impact of the Anticancer Drug NT157 on Tyrosine Kinase Signaling Networks.

Shih-Ping Su,Efrat Flashner-Abramson,Mor Gal,Shoshana Klein,Jianmin Wu,Roger J Daly,Rachel S Lee,Alexander Levitzki

doi:10.1158/1535-7163.mct-17-0377

Abstract

The small-molecule drug NT157 has demonstrated promising efficacy in preclinical models of a number of different cancer types, reflecting activity against both cancer cells and the tumor microenvironment. Two known mechanisms of action are degradation of insulin receptor substrates (IRS)-1/2 and reduced Stat3 activation, although it is possible that others exist. To interrogate the effects of this drug on cell signaling pathways in an unbiased manner, we have undertaken mass spectrometry-based global tyrosine phosphorylation profiling of NT157-treated A375 melanoma cells. Bioinformatic analysis of the resulting dataset resolved 5 different clusters of tyrosine-phosphorylated peptides that differed in the directionality and timing of response to drug treatment over time. The receptor tyrosine kinase AXL exhibited a rapid decrease in phosphorylation in response to drug treatment, followed by proteasome-dependent degradation, identifying an additional potential target for NT157 action. However, NT157 treatment also resulted in increased activation of p38 MAPK α and γ, as well as the JNKs and specific Src family kinases. Importantly, cotreatment with the p38 MAPK inhibitor SB203580 attenuated the antiproliferative effect of NT157, while synergistic inhibition of cell proliferation was observed when NT157 was combined with a Src inhibitor. These findings provide novel insights into NT157 action on cancer cells and highlight how globally profiling the impact of a specific drug on cellular signaling networks can identify effective combination treatments. Mol Cancer Ther; 17(5); 931-42. ©2018 AACR.

Highlights

The past two decades have seen major advances in our understanding of the molecular mechanisms that underpin the different hallmarks of cancer, and these have led to the development of new classes of therapies that selectively target molecular mechanisms of specific importance to the survival and proliferation of cancer cells
Global phosphoproteomic profiling of NT157-treated cells To determine the impact of NT157 on the tyrosine phosphoproteome, A375 cells were treated with either vehicle control or drug for 1 or 8 hours
We have utilized a global phosphoproteomic approach to determine that NT157 exerts complex effects on intracellular signaling networks, with resolution of 5 different clusters of tyrosine phosphorylation sites that differ in their directionality of response to drug treatment as well as temporal regulation

Summary

Introduction

The past two decades have seen major advances in our understanding of the molecular mechanisms that underpin the different hallmarks of cancer, and these have led to the development of new classes of therapies that selectively target molecular mechanisms of specific importance to the survival and proliferation of cancer cells. The inherent genomic instability of cancer cells and their propensity to acquire additional mutations, coupled with intratumoral heterogeneity, means that the development of resistance to targeted therapies represents a major clinical problem [1] In light of this issue, the development of agents that can target several oncogenic signal transduction pathways, and/or factors in the tumor microenvironment that contribute to disease progression, has recently gained attention [2, 3]. One mechanism of NT157 function is via degradation of insulin receptor substrate (IRS)-1/2 and inhibition of proproliferative and survival signaling mediated by these docking proteins This mechanism involves direct allosteric modulation of the IGF-1R, uncoupling of the receptor from IRS-1/2, recruitment of Shc, and activation of the Erk MAP kinases. The ability of NT157 to inhibit two independent signaling pathways critical for cancer cell proliferation, survival, and metastasis, as well as cancer cell interaction with the tumor microenvironment, makes it a promising anticancer agent that may prove refractory to development of acquired drug resistance

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