TPCA-1 Is a Direct Dual Inhibitor of STAT3 and NF-κB and Regresses Mutant EGFR-Associated Human Non–Small Cell Lung Cancers

Abstract

Epidermal growth factor receptor (EGFR) is a clinical therapeutic target to treat a subset of non-small cell lung cancer (NSCLC) harboring EGFR mutants. However, some patients with a similar kind of EGFR mutation show intrinsic resistance to tyrosine kinase inhibitors (TKI). It indicates that other key molecules are involved in the survival of these cancer cells. We showed here that 2-[(aminocarbonyl)amino]-5 -(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1), a previously reported inhibitor of IkB kinases (IKK), blocked STAT3 recruitment to upstream kinases by docking into SH2 domain of STAT3 and attenuated STAT3 activity induced by cytokines and cytoplasmic tyrosine kinases. TPCA-1 is an effective inhibitor of STAT3 phosphorylation, DNA binding, and transactivation in vivo. It selectively repressed proliferation of NSCLC cells with constitutive STAT3 activation. In addition, using pharmacologic and genetic approaches, we found that both NF-kB and STAT3 could regulate the transcripts of interleukin (IL)-6 and COX-2 in NSCLC harboring EGFR mutations. Moreover, gefitinib treatment only did not efficiently suppress NF-kB and STAT3 activity. In contrast, we found that treatment with TKIs increased phosho-STAT3 level in target cells. Inhibiting EGFR, STAT3, and NF-kB by combination of TKIs with TPCA-1 showed increased sensitivity and enhanced apoptosis induced by gefitinib. Collectively, in this work, we identified TPCA-1 as a direct dual inhibitor for both IKKs and STAT3, whereas treatment targeting EGFR only could not sufficiently repress NF-kB and STAT3 pathways for lung cancers harboring mutant EGFR. Therefore, synergistic treatment of TPCA-1 with TKIs has potential to be a more effective strategy for cancers. Mol Cancer Ther; 13(3); 617-29. Ó2014 AACR.

Non-small-cell lung cancer

“…An increasing amount of evidence even indicates that EGFR inhibitors activate STAT3 (REFS 152,153) almost immediately after treatment, via phosphorylation of Tyr705. Eliminating STAT3 activation as well as inhibiting NF-κB signalling can enhance the antiproliferative effects of EGFR inhibitors in vitro and in vivo 154,155 . Thus, it is very important to identify biomarkers to select patients with initial good responses, but rapid development of resistance, to test and target novel therapeutic approaches.…”

Co-activation of STAT3 and YES-Associated Protein 1 (YAP1) Pathway in EGFR-Mutant NSCLC

“…EGFR mutations activate MAPK, PI3K-AKT, and STAT3 directly or through IL-6-JAK2 (5,10,21). An IL-6-mediated crosstalk between NF-κB and STAT3 has been described in EGFR-mutant NSCLC cells (16). pSTAT3-Tyr705 is induced two hours after erlotinib or gefitinib treatment (7,8,16).…”

“…TPCA-1 (2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide), a nonpeptidic small molecule inhibitor of the inhibitor of κB kinase-2 (IKK2) (15), and the Src homology 2-domain of STAT3 (16), was purchased from Sigma Aldrich. AZD0530 (SFK inhibitor; saracatinib) and the third-generation EGFR TKI AZD9291 were purchased from Selleck Chemicals.…”

Dehydrocrenatidine Is a Novel Janus Kinase Inhibitor

“…2E). LY294002, a PI3K inhibitor and TPCA-1 (Nan et al, 2014), a dual inhibitor of STAT3 and NF-kB were used as controls. These data suggested that dehydrocrenatidine selectively inhibited JAK-STAT3 signaling without affecting PI3K-AKT pathway and NF-kB pathway.…”