Acquired resistance to EGFR tyrosine kinase inhibitors is mediated by the reactivation of STC2/JUN/AXL signaling in lung cancer

Abstract

Constitutive activation of the epidermal growth factor receptor (EGFR) signaling pathway is implicated in the initiation and progression of lung cancer. EGFR tyrosine kinase inhibitor (TKI)-targeted therapy has become the standard treatment for nonsmall cell lung cancer (NSCLC) patients. However, acquired resistance to these agents remains a major obstacle for managing NSCLC. Here, we investigated a novel strategy to overcome EGFR TKI resistance by targeting the stanniocalcin 2 (STC2)-JUN-AXL pathway. We revealed that STC2 was expressed at significantly higher levels in EGFR TKI-resistant cells. Further, clinical analysis showed that STC2 expression was increased after the development of EGFR TKI resistance and that higher levels were correlated with shorter progression-free survival in EGFR TKI-treated lung cancer patients. Moreover, STC2 overexpression in EGFR TKI-sensitive cells resulted in EGFR TKI resistance. Conversely, genetic silencing of STC2 rendered EGFR TKI-resistant cells more sensitive to EGFR TKIs. Mechanically, STC2 enhanced AXL promoter activity by increasing the phosphorylation of c-Jun, which is an indispensable transcription factor that transactivates AXL. STC2 promoted activation of the JUN-AXL-extracellular signal-regulated kinase (ERK) signaling axis in lung cancer cells. Pharmacological or genetic inhibition of AXL-ERK activity inhibited STC2-mediated EGFR TKI resistance. We also demonstrated that PE2988 cells, a C797Sindependent osimertinib-resistant primary cancer cell line from a lung cancer patient, responded to combined AXL inhibitor and osimertinib treatment. In conclusion, our research indicates that STC2 overexpression is important for acquired resistance to EGFR TKIs and that STC2-JUN-AXL-ERK signaling might be a potential therapeutic target to overcome resistance to EGFR TKIs.

miR-146b-5p Enhances the Sensitivity of NSCLC to EGFR Tyrosine Kinase Inhibitors by Regulating the IRAK1/NF-κB Pathway

“…PE2988 and PE3479 cells were isolated from malignant pleural fluids of EGFR-mutant lung cancer patients with acquired resistance to osimertinib and then cultured using the previously reported protocol. 54 These cell lines were authenticated using short tandem repeat profiling. These cell lines were routinely tested for mycoplasma and free of mycoplasma contamination.…”

“…RNA extraction and qRT-PCR were performed as previously described. 54 Briefly, total RNA was isolated using the Tri reagent (Molecular Research Center; Cincinnati, OH, USA) and reverse transcribed to cDNA using a High-Capacity cDNA reverse transcription kit (ThermoFisher Scientific; Waltham, MA, USA). qPCR was performed on an ABI 7500 system using a standard protocol, with TATA box-binding protein ( TBP ) or RNU6B as internal controls for mRNA or miRNA, respectively.…”

“…After centrifugation, the primary cancer cells were isolated and cultured using the previously reported protocol. 54 Media were replaced after every 2–3 days, and the cells were harvested after 10 days. Total RNA was extracted, and the expression levels of miR-146b-5p and IRAK1 were determined using qRT-PCR.…”

“…Cytotoxicity and apoptosis assays were performed as previously described. 54 Briefly, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays (Affymetrix; Santa Clara, CA, USA) were used to evaluate the cytotoxic effects of the EGFR TKIs. Briefly, 3 × 10 3 cells per well were plated in 96-well plates and treated with the indicated drugs.…”

Enapotamab vedotin, an AXL-specific antibody-drug conjugate, shows preclinical antitumor activity in non-small cell lung cancer

“…Although these results represent small numbers and the prior treatment status of the models is not available, it is tempting to speculate that the responses depend on prior clinical treatment, either with chemotherapy in the KRAS segment and with EGFRi in the EGFR-mutant segment, that could induce targetable AXL expression levels. Signaling pathways downstream of AXL have been reported to induce EGFRi resistance via signals converging on the PI3K/Akt and MAPK pathways (36).…”