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.
View: Text | PDF
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

×

Figure 6

High CRIPTO1 expression correlates with intrinsic EGFR-TKI resistance in EGFR-mutated NSCLC patients.

Options: View larger image (or click on image) Download as PowerPoint
High CRIPTO1 expression correlates with intrinsic EGFR-TKI resistance in...
(A) High CRIPTO1 expression correlated with intrinsic gefitinib or erlotinib resistance (Student’s t test, P = 0.0001) in EGFR-mutated NSCLC patients (n = 85, see Supplemental Table 3 for reference). Levels of expression (scores 0–3) of CRIPTO1 IHC by a pathologist (M. Raffeld) are shown. Sensitive patients (those with PRs [yellow], CRs [red], or SD [green] of more than 4-month duration, n = 70) group and patients intrinsically resistant (those with PD [purple] or SD [blue] of 4-month duration or less, n = 15) to erlotinib or gefitinib treatment. (B) Representative CRIPTO1 IHC images in sensitive (tumor nos. 29 and 12) and intrinsically resistant (tumor nos. 1 and 3) EGFR-mutated NSCLC patients who received gefitinib and erlotinib treatment (See Supplemental Table 2). Original magnification, ×400. (C) Schemas illustrating the identified mechanisms of CRIPTO1-mediated resistance to EGFR inhibitions. Left: Targeting EGFR in EGFR-mutated (EGFR+)/CRIPTO1-negative cells. Middle: Targeting EGFR in EGFR-mutated/CRIPTO1-positive cells. Right: Cotargeting EGFR and SRC in EGFR-mutated/CRIPTO1-positive cells. Solid lines indicate the effects of CRIPTO1 on its downstream effectors. Gray lines depict to what extent the signaling pathways are blocked by target specific inhibitors.