Phosphoproteomic analysis identifies activated MET-axis PI3K/AKT and MAPK/ERK in lapatinib-resistant cancer cell line

Abstract

Lapatinib, a dual inhibitor of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) tyrosine kinases, has shown promising results as a growth inhibitor of HER2-positive cancer cells in vitro. However, similar to other EGFR-targeting drugs, acquired resistance to lapatinib by HER2-positive cancer cells remains a major clinical challenge. To elucidate resistance mechanisms to EGFR/HER2-targeting agents, we performed a systematic quantitative comparison of the phosphoproteome of lapatinib-resistant (LR) human gastric cancer cells (SNU216-LR) versus parental cells (SNU216) using a titanium dioxide (TiO2) phosphopeptide enrichment method and analysis with a Q-Exactive hybrid quadrupole-Orbitrap mass spectrometer. Biological network analysis of differentially expressed phosphoproteins revealed apparent constitutive activation of the MET-axis phosphatidylinositide 3-kinase (PI3K)/α-serine/threonine-protein kinase (AKT) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathways in SNU216-LR. Inhibition of the PI3K/AKT and MAPK/ERK signaling pathways in SNU216-LR also leads to cell cycle arrest, confirming the biological network analysis. Lapatinib sensitivity was restored when cells were treated with several molecular targeting agents in combination with lapatinib. Thus, by integrating phosphoproteomic data, protein networks and effects of signaling pathway modulation on cell proliferation, we found that SNU216-LR maintains constitutive activation of the PI3K/AKT and MAPK/ERK pathways in a MET-dependent manner. These findings suggest that pathway activation is a key compensatory intracellular phospho-signaling event that may govern gastric cancer cell resistance to drug treatment.

EPHA2 blockade reverses acquired resistance to afatinib induced by EPHA2‐mediated MAPK pathway activation in gastric cancer cells and avatar mice

“…Based on the current results, we supposed that the reactivation of PI3K/AKT pathway might also be caused by other upstream molecules. Previous studies have reported that MET and SFKs, conferred EGFR‐TKI resistance by activating PI3K/AKT and MAPK signaling . However, we did not detect abnormal expression of these molecules at transcriptional and protein levels in the present study.…”

Combined HSP90 and kinase inhibitor therapy: Insights from The Cancer Genome Atlas

“…Indeed, in a random mutagenesis screen of BCR-ABL, while numerous KI resistance mutants were identified, no H90Ins resistance mutants were identified (Tauchi et al 2011). Alternatively, a tumor may also compensate for the inhibition of one growth promoting kinase by activating another kinase signaling pathway (Chen et al 2012); (Lee et al 2013). Such phenomena demonstrate the need to simultaneously inhibit multiple kinases, which may be accomplished by targeting HSP90.…”

MET-targeted therapy for gastric cancer: the importance of a biomarker-based strategy

“…Furthermore, excessive activation of MET results in the transphosphorylation of and formation of heterodimers with other receptor tyrosine kinases, including EGFR, HER2, HER3, and RET [29]. Such heterodimers allow bypass signaling that can give rise to resistance to EGFR-or HER2-targeted therapy, as has been demonstrated in NSCLC cells [30,31] and colorectal cancer cells [32,33] as well as in gastric cancer cells [34][35][36].…”