TD-19, an erlotinib derivative, induces epidermal growth factor receptor wild-type nonsmall-cell lung cancer apoptosis through CIP2A-mediated pathway.

Some patients with nonsmall-cell lung cancer (NSCLC) without epidermal growth factor receptor (EGFR) mutations still respond to gefitinib and erlotinib, suggesting that there may be a mechanism(s) other than the EGFR pathway that mediates the tumoricidal effects. In the current study, we tested the efficacy of TD-19, a novel compound chemically modified from erlotinib, which has more potent apoptotic effects than erlotinib in EGFR wild-type NSCLC cell lines. TD-19 induced significant cell death and apoptosis in H358, H441, H460, and A549 cells, as evidenced by increased caspase-3 activity and cleavage of procaspase-9 and poly (ADP-ribose) polymerase. The apoptotic effect of TD-19 in H460 cells, which were resistant to erlotinib, was associated with downregulation of cancerous inhibitor of protein phosphatase 2A (CIP2A), increased protein phosphatase 2A (PP2A) activity, and decreased AKT phosphorylation, but minimal effects on EGFR phosphorylation. Overexpression of CIP2A partially protected the H460 cells from TD-19-induced apoptosis. Okadaic acid, a known PP2A inhibitor, significantly reduced TD-19-induced apoptosis, while forskolin, which increased PP2A activity, increased the apoptotic effect of TD-19. TD-19 inhibited the growth of H460 xenograft tumors by ∼80%. We conclude that TD-19 exerted tumoricidal effects on NSCLC cells. TD-19 provides proof that the CIP2A pathway may be a novel target for the treatment of EGFR wild-type NSCLC.

Signal transducer and activator of transcription 3 as molecular therapy for non-small-cell lung cancer.

INTRODUCTION: Targeting signal transducer and activator of transcription 3 (STAT3), a transcription factor that modulates survival-directed transcription, is often persistently activated in epidermal growth factor receptor (EGFR) wild-type non-small-cell lung cancer (NSCLC). The aim of this study was to determine whether sorafenib and its derivative can inhibit EGFR wild-type NSCLC via STAT3 inactivation. METHODS: EGFR wild-type NSCLC cell lines (A549 H292 H322 H358 and H460) were treated with sorafenib or SC-1, a sorafenib derivative that closely resembled sorafenib structurally but was devoid of kinase inhibitory activity. Apoptosis and signal transduction were analyzed. In vivo efficacy was determined in nude mice with H460 and A549 xenograft. RESULTS: SC-1 had better effects than sorafenib on growth inhibition and apoptosis in all tested EGFR wild-type NSCLC lines. SC-1 reduced STAT3 phosphorylation at tyrosine 705 in all tested EGFR wild-type NSCLC cells. The expression of STAT3-driven genes, including cylcin D1 and survivin, was also repressed by SC-1. Ectopic expression of STAT3 in H460 cells abolished apoptosis in SC-1-treated cells. Sorafenib and SC-1 enhanced Src homology-2 containing protein tyrosine phosphatase-1 (SHP-1) activity, whereas knockdown of SHP-1, but not SHP-2 or protein-tyrosine phosphatase 1B (PTP-1B), by small interference RNA reduced SC-1-induced apoptosis. SC-1 significantly reduced H460 and A549 tumor growth in vivo through SHP-1/STAT3 pathway. CONCLUSIONS: SC-1 provides proof that targeting STAT3 signaling pathway may be a novel approach for the treatment of EGFR wild-type NSCLC.