Dual Targeting of EGFR and IGF1R in the TNFAIP8 Knockdown Non–Small Cell Lung Cancer Cells

Abstract

Aberrant regulation of EGFR is common in non-small cell lung carcinomas (NSCLC), and tumor resistance to targeted therapies has been attributed to emergence of other cooccurring oncogenic events, parallel bypass receptor tyrosine kinase pathways including IGF1R, and TNFadriven adaptive response via NF-kB. TNFAIP8, TNFa-inducible protein 8, is an NF-kB-activated prosurvival and oncogenic molecule. TNFAIP8 expression protects NF-kB-null cells from TNFa-induced cell death by inhibiting caspase-8 activity. Here, we demonstrate that knockdown of TNFAIP8 inhibited EGF and IGF-1-stimulated migration in NSCLC cells. TNFAIP8 knockdown cells showed decreased level of EGFR and increased expression of sorting nexin 1 (SNX1), a key regulator of the EGFR trafficking through the endosomal compartments, and treatment with SNX1 siRNA partially restored EGFR expression in these cells. TNFAIP8 knockdown cells also exhibited downregulation of IGF-1-induced pIGF1R and pAKT, and increased expression of IGF-1-binding protein 3 (IGFBP3), a negative regulator of the IGF-1/IGF1R signaling. Consistently, treatment of TNFAIP8 knockdown cells with IGFBP3 siRNA restored pIGF1R and pAKT levels. TNFAIP8 knockdown cells had enhanced sensitivities to inhibitors of EGFR, PI3K, and AKT. Furthermore, IHC expression of TNFAIP8 was associated with poor prognosis in NSCLC. These findings demonstrate TNFAIP8-mediated regulation of EGFR and IGF1R via SNX1 and IGFBP3, respectively. We posit that TNFAIP8 is a viable, multipronged target downstream of the TNFa/NF-kB axis, and silencing TNFAIP8 may overcome adaptive response in NSCLC. Implications: TNFAIP8 and its effectors SNX1 and IGFBP3 may be exploited to improve the efficacy of molecular-targeted therapies in NSCLC and other cancers.

Current research status of TNFAIP8 in tumours and other inflammatory conditions (Review)

“…EGFR is one of the most common growth factors implicated in numerous malignancies. A previous study showed that TNFAIP8-knockdown enhances the expression of sorted nexin 1 and upregulates the endosomal/lysosomal transport pathway, resulting in decreased EGFR expression, decreased EGF-induced phosphorylated extracellular signal-regulated kinase expression, reduced cell migration and increased sensitivity to EGFR mutation-selective tyrosine kinase inhibitors (68). In TNFAIP8-knockdown cells, the expression of IGF-1 binding protein 3 (IGFBP3) was shown to be increased, leading to a decrease in the IGF-1-induced expression of pIGF1R and p-Akt, decreased cell migration, and enhanced sensitivity to PI3K and Akt inhibitors, suggesting that targeting TNFAIP8 can inhibit adaptive responses and provided a rational strategy for the management of aggressive NSCLC (68).…”

MicroRNA-197 promotes proliferation and inhibits apoptosis of gallbladder cancer cells by targeting insulin-like growth factor-binding protein 3

“…26 Day et al found that using IGFBP3 siRNA to treat NSCLC cells with TNFAIP8 knockdown can upregulate pAKT levels and promote cell proliferation. 27 By blocking the IGF1 signal cascade, it was possible to confirm to a certain degree that overexpression of IGFBP3 can induce apoptosis in NSCLC cells in vitro and enhance cellular response to cisplatin. 28 In lung adenocarcinoma and hepatocellular carcinoma, testis-specific protein Y-linked 1 (TSPY1) can directly bind to the promoter of IGFBP3 to inhibit its expression.…”

TIPE Regulates DcR3 Expression and Function by Activating the PI3K/AKT Signaling Pathway in CRC

“…Numerous studies have revealed that TIPE is overexpressed in various tumors and that its overexpression is associated with clinical parameters and metastasis. In non-small-cell lung cancer (NSCLC), the expression of TIPE is downregulated via a decrease in EGFR levels and an increase in SNX (a key regulator of EGFR transporters) levels, which further inhibits ECL- and IGF-1-stimulated NSCLC cell migration ( 5 ). In gastric cancer patients, increased TIPE expression in tumor tissue is related to lymph node metastasis, tumor-node-metastasis (TNM) stage, and poor prognosis ( 24 ).…”

“…Tumor necrosis factor-induced protein-8 (TNFAIP8/TIPE; also called SCC-S2, MDC-3.13, GG2-1, and NDED) was the first identified protein in the TIPE family and is closely associated with tumors and inflammation ( 4 ). As an antiapoptotic and carcinogenic molecule, TIPE promotes the growth, proliferation and migration of cancer cells ( 5 ). The activation of TNF-α and NF-κB in the inflammatory environment can induce TIPE expression ( 6 ).…”