CRIPTO1 expression in EGFR-mutant NSCLC elicits intrinsic EGFR-inhibitor resistance
Kang-Seo Park, … , Yisong Wang, Giuseppe Giaccone
Kang-Seo Park, … , Yisong Wang, Giuseppe Giaccone
Published June 9, 2014
Citation Information: J Clin Invest. 2014;124(7):3003-3015. https://doi.org/10.1172/JCI73048.
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Research Article Oncology

CRIPTO1 expression in EGFR-mutant NSCLC elicits intrinsic EGFR-inhibitor resistance

Abstract

The majority of non–small cell lung cancer (NSCLC) patients harbor EGFR-activating mutations that can be therapeutically targeted by EGFR tyrosine kinase inhibitors (EGFR-TKI), such as erlotinib and gefitinib. Unfortunately, a subset of patients with EGFR mutations are refractory to EGFR-TKIs. Resistance to EGFR inhibitors reportedly involves SRC activation and induction of epithelial-to-mesenchymal transition (EMT). Here, we have demonstrated that overexpression of CRIPTO1, an EGF-CFC protein family member, renders EGFR-TKI–sensitive and EGFR-mutated NSCLC cells resistant to erlotinib in culture and in murine xenograft models. Furthermore, tumors from NSCLC patients with EGFR-activating mutations that were intrinsically resistant to EGFR-TKIs expressed higher levels of CRIPTO1 compared with tumors from patients that were sensitive to EGFR-TKIs. Primary NSCLC cells derived from a patient with EGFR-mutated NSCLC that was intrinsically erlotinib resistant were CRIPTO1 positive, but gained erlotinib sensitivity upon loss of CRIPTO1 expression during culture. CRIPTO1 activated SRC and ZEB1 to promote EMT via microRNA-205 (miR-205) downregulation. While miR-205 depletion induced erlotinib resistance, miR-205 overexpression inhibited CRIPTO1-dependent ZEB1 and SRC activation, restoring erlotinib sensitivity. CRIPTO1-induced erlotinib resistance was directly mediated through SRC but not ZEB1; therefore, cotargeting EGFR and SRC synergistically attenuated growth of erlotinib-resistant, CRIPTO1-positive, EGFR-mutated NSCLC cells in vitro and in vivo, suggesting that this combination may overcome intrinsic EGFR-inhibitor resistance in patients with CRIPTO1-positive, EGFR-mutated NSCLC.

Authors

Kang-Seo Park, Mark Raffeld, Yong Wha Moon, Liqiang Xi, Caterina Bianco, Trung Pham, Liam C. Lee, Tetsuya Mitsudomi, Yasushi Yatabe, Isamu Okamoto, Deepa Subramaniam, Tony Mok, Rafael Rosell, Ji Luo, David S. Salomon, Yisong Wang, Giuseppe Giaccone

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Figure 1

CRIPTO1 expression in NSCLC tumors and cell lines.

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CRIPTO1 expression in NSCLC tumors and cell lines. (A) Western blot anal...
(A) Western blot analysis of CRIPTO1, total SRC, phosphorylated SRC, pEGFR, EGFR, and Vimentin in 21 NSCLC patient samples. Relative expression of endogenous CRIPTO1 in tumor cells and exogenous CRIPTO1 in HCC827 cells were shown after normalization against β-actin (lanes 15–21, HCC827 mock, and HCC827/CRIPTO1). Note that lanes 1–14 were not used for comparison, as they were derived from different blots, and that the lanes on 2 sides of the thin black lines were run on the same gel but were noncontiguous. (B) CRIPTO1 expression in 31 NSCLC cell lines by Western blot. (C) CRIPTO1 mRNA expression in 35 NSCLC cell lines by RT-PCR. CRIPTO1 primers could only amplify CRIPTO1 in CRIPTO1-positive/CRIPTO3-negative (H727) cells, but not CRIPTO3 in CRIPTO3-positive/CRIPTO1-negative (H69) cells (inset).