A Small Molecule Targeting Human MEK1/2 Enhances ERK and p38 Phosphorylation under Oxidative Stress or with Phenothiazines

Abstract

Small molecules are routinely used to inhibit protein kinases, but modulators capable of enhancing kinase activity are rare. We have previously shown that the small molecule INR119, designed as an inhibitor of MEK1/2, will enhance the activity of its fission yeast homologue, Wis1, under oxidative stress. To investigate the generality of these findings, we now study the effect of INR119 in human cells under similar conditions. Cells of the established breast cancer line MCF-7 were exposed to H2O2 or phenothiazines, alone or combined with INR119. In line with the previous results in fission yeast, the phosphorylation of the MAPKs ERK and p38 increased substantially more with the combination treatment than by H2O2 or phenothiazines, whereas INR119 alone did not affect phosphorylation. We also measured the mRNA levels of TP53 and BAX, known to be affected by ERK and p38 activity. Similarly, the combination of INR119 and phenothiazines increased both mRNAs to higher levels than for phenothiazines alone. In conclusion, the mechanism of action of INR119 on its target protein kinase may be conserved between yeast and humans.

Targeting Ca2+ and Mitochondrial Homeostasis by Antipsychotic Thioridazine in Leukemia Cells

“…CHOP induces the expression of GADD34 and increases levels of ERO1α, which results in the production of cytotoxic ROS [ 53 ]. As downstream signaling, the phosphorylation of JNK and other stress-related signaling molecules (ERK1/2 and p38) is in accordance with observed results from fluphenazine in MCF-7 breast cancer cells [ 54 , 55 ]. The knockdown of CHOP in K562 cells resulted in an attenuation of TR-promoted cytotoxicity, thereby demonstrating that ER stress contributes to TR-induced cell death.…”

Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors

“…Inhibitors targeting the SMAD-interacting enzymes such as AKT/PKB (Ser/Thr kinase/protein kinase B), CDK (cyclin-dependent kinase), GSK GSK3b (axin/glycogen synthase kinase 3 beta), and ERK (extracellular signal-related kinase) are cataloged in Table 1 [ 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 ]. These inhibitors act by modulating the phosphorylation activity of the kinases and thereby regulate their interaction, the R-SMADs, and SMAD-mediated signaling in epithelial and mesenchymal cells.…”

“…Significant advancements have been observed in the area of small-molecule inhibitors of AKT functions through different mechanisms. In addition, pleckstrin homology domain, ATP-competitive, and allosteric inhibitors of AKT are noteworthy in developing clinical trials, and therapeutic benefits in treating different solid tumors have been observed [ 83 ]. A preclinical study of MK-2206 in epithelial morphology of pancreatic cancer cells by Wang et al [ 72 ] showed that AKT phosphorylation is inhibited, and cell proliferation is attenuated by the application of the MK-2206 inhibitor.…”

“…Breast cancer [83] Another potential inhibitor is nitazoxanide (NTZ), which targets CDK1 by inhibiting phosphorylation of CDK1 at Thr161, as studied by Huang et al [74]. It is thought that CDK1 phosphorylation might enhance the activity of SMAD3 and nucleocytoplasmic trafficking and stimulate SMAD-mediated cell proliferation in epithelioid glioblastoma cells.…”