The FGFR4-388Arg allele, where an arginine substitutes a glycine in the 388 codon of the FGFR4 gene, has been associated to poorer patient outcome in different tumor types. In lung cancer, the variant has been related to shorter overall survival in adenocarcinoma (ADC) patients, while no relationship with squamous cell carcinoma prognosis (SCC) has been reported. Mechanistically, the FGFR4-388Arg variant has been related to increased MAPK pathway activation and to EMT in prostate cancer in vitro models. Furthermore, the variant has been associated with higher STAT3 signaling in murine models of breast and lung cancer. However, so far the molecular biology for this FGFR4 variant in lung cancer patients has not been addressed.

We overexpressed the FGFR4-388Gly and FGFR4-388Arg variants in lung cancer cell lines from different histologic backgrounds and performed tumorogenicity surrogate assays and downstream signaling activation assessment. In the generated stable cell lines, we also determined the expression of EMT markers. Furthermore, we determined the FGFR4 variant and the FGFR4 and N-cadherin mRNA expression in a cohort of NSCLC patients (N=65) and correlated these data to patient outcome.

We reported that FGFR4-388Arg increases tumorogenicity in lung cancer cell lines. Mechanistically, these functional effects seem to be mediated by MAPK and STAT3 overactivation and by the induction of an EMT phenotype, which includes N-cadherin increased expression. In fact, this induction of N-cadherin protein expression by the FGFR4-388Arg variant seems to be responsible for the pro-oncogenic effects reported. In NSCLC patient tumor samples, the FGFR4-388Arg variant correlates with higher N-cadherin expression and with poorer survival.

In conclusion, the FGFR4-388Arg variant is a potential prognostic biomarker in NSCLC, including ADC and SCC patients. This variant increases tumorogenesis through the activation of MAPK and STAT3 signaling pathways and through the promotion of an EMT phenotype.

Citation Format: Álvaro Quintanal-Villalonga, Rocío Suárez, Laura Ojeda-Márquez, Santiago Ponce-Aix, Amancio Carnero, Luis Paz-Ares, Irene Ferrer, Sonia Molina-Pinelo. The FGFR4-388Arg variant exerts pro-tumorogenic effects in lung cancer by inducing an EMT phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3334. doi:10.1158/1538-7445.AM2017-3334