Abstract 1861: Estrogen modulation of fibroblast growth factor signaling in non-small cell lung cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA The estrogen signaling pathway induces proliferation in non-small cell lung cancer (NSCLC) and represents a novel therapeutic target for lung cancer. Estrogen receptor β (ERβ) is the predominant ER isoform in lung cancer and we have previously shown that high cytoplasmic ERβ combined with low progesterone receptor (PR) expression is a poor prognostic marker for NSCLC patients. To further elucidate the biological differences between ERβ high/PR low versus ERβ low/PR high expressing lung tumors, a mRNA microarray analysis using the Illumina HT-12 V4 Bead Chip platform was performed using RNA extracted from 64 cases. 165 genes were differentially expressed between these two groups at P<001. Fibroblast growth factor receptor 1 (FGFR1) was a highly over-expressed gene associated with ERβ high tumors (2.1-fold, P<0.004), while the decoy receptor for FGFR ligands, fibroblast growth factor receptor like-1 (FGFR5), was down-regulated (0.54-fold, P<0.0001). Ingenuity Pathway analysis revealed a network among the 165 differentially expressed genes that linked FGFR1 and FGFR5 to the ER. To analyze cross-talk between the FGF and E2 pathways, we determined the FGF/FGFR profile in a panel of three FGFR1 amplified and five non-amplified NSCLC cell lines. FGF2, 3, 10, and 19 were the most highly secreted FGFs in the cell line panel. FGFR1 amplified cells secreted statistically more FGF3, 6 and 10 compared to non-amplified cells. β-estradiol (E2) induced secretion of FGF2 in a cell line without FGFR1 amplification. FGFR3 and 5 were ubiquitously expressed across all cell lines while FGFR1, 2 and 4 expression was higher in amplified cell lines. There was no relationship between ERβ protein expression and FGFR1 amplification status or FGFR1-5 protein expression. Because FGF signaling has been shown to increase stem cell-like phenotypes in breast cancer, we determined basal and E2-stimulated expression of the stem cell markers, SOX2 and OCT4. Basal SOX2 and OCT4 were more highly expressed in FGFR1 amplified cells compared to non-amplified cells. SOX2 and OCT4 protein expression were increased by E2 treatment in FGFR1 non-amplified cells, with lesser effects in FGFR1 amplified H520 cells. SOX2 expression was also down-regulated in lung sections from mice treated with a combination of the anti-estrogen fulvestrant and the aromatase inhibitor anastrozole. Finally, we have shown that in FGFR1 non-amplified cells, the anti-proliferative effect of a pan-FGFR inhibitor, AZD4547, can be enhanced in the presence of the anti-estrogen fulvestrant. These results suggest that there is an interaction between the estrogen and FGF signaling pathways in lung cancer and provides a rationale for combination treatment of NSCLC tumors. Further characterization of the molecular types of NSCLC that will benefit from joint therapy is warranted. This work was supported by P50 CA090440. Citation Format: Laura P. Stabile, Natalie J. Rothenberger, Marjorie Romkes, Lisa Koodie, Mariya Farooqui, Sanja Dacic, Jill M. Siegfried. Estrogen modulation of fibroblast growth factor signaling in non-small cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1861. doi:10.1158/1538-7445.AM2015-1861