Abstract 2852: SNAI2 expression by cancer-associated fibroblasts is a negative prognostic factor in non-small cell lung cancer
Authors: Andriani Francesca , Leone Giorgia , Landoni Elena , Facchinetti Federica , Caputo Tiziana , Baldoli Erika , Miceli Rosalba , Mariani Luigi , Pastorino Ugo , Pelosi Giuseppe , Sozzi Gabriella , Roz Luca 
Published: May 2015

The tumor microenvironment is increasingly recognized as a contributor to cancer development and progression since several stromal components, including fibroblasts, interact with cancer cells regulating their behavior and ultimately affecting tumor phenotype. Using primary cultures of human fibroblasts isolated from resected lung cancers we previously demonstrated that co-injection with cancer cells results in increased tumorigenicity and altered expression of ECM related genes in heterotypic tumors. To identify factors involved in the cross-talk between fibroblasts and lung cancer cells, microarray gene expression profiling was performed on 60 fibroblast lines from cancerous and normal lung tissue from primary lung cancer patients, including 25 pairs of normal (NF) and cancer-associated fibroblasts (CAF) from the same patients. Lines were also characterized for presence of the activation marker alpha-SMA and for in vivo pro-tumorigenic activity by co-injection with A549 adenocarcinoma cells. Class comparison analyses identified: (i) Factors highly expressed in cancer-associated fibroblasts (CAF) compared to normal fibroblasts (NF): RHOB, SNAI2, EDIL3, LRRN3, CHN1, CTSC, NOPE and DOCK10; (ii) Genes highly expressed in activated fibroblasts: POSTN, TNFAIP6, CLEC2B and (iii) Genes associated with an in vivo pro-tumorigenic phenotype: CNTN3, ELOVL6, MET, XPO1.

To explore the potential prognostic value of these microenvironment related markers, we selected antibodies against 20 proteins differentially expressed in lung fibroblasts and evaluated their performance in immunohistochemistry on FFPE sections of 74 cases of NSCLC. Selection criteria to prioritize candidates for IHC were based on results from molecular analyses (both microarray hybridization and Real-Time PCR validation) and involvement in biological pathways identified as potentially relevant by Gene Set Enrichment Analysis (GSEA). The frequency of positive cells was evaluated on: cancer cells, cancer-associated fibroblasts (CAF) and fibroblasts in normal tissue adjacent (AF) or distant (NF) from the surgical margin. This in-depth analysis revealed heterogeneous expression of different proteins with factors predominantly expressed by cancer cells (LRRN3) and others by the stromal component (CLEC2B). Among factors expressed by fibroblasts, positivity for NOPE, MET, CTSC and CLEC2B was detected in the majority of cases (60-70%) and they were generally expressed at higher frequency by CAF compared to NF. In univariate Cox models, SNAI2 expression by CAF was shown to correlate with worst overall survival (p=0.0288) and we further identified association of CNTN3 expression by CAF with shorter disease free survival (p=0.0125).These findings strengthen the hypothesis that identification of factors responsible for proficient tumor-stroma cross-talk could be instrumental in innovative strategies for risk assessment.

Citation Format: Francesca Andriani, Giorgia Leone, Elena Landoni, Federica Facchinetti, Tiziana Caputo, Erika Baldoli, Rosalba Miceli, Luigi Mariani, Ugo Pastorino, Giuseppe Pelosi, Gabriella Sozzi, Luca Roz. SNAI2 expression by cancer-associated fibroblasts is a negative prognostic factor in non-small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2852. doi:10.1158/1538-7445.AM2014-2852