Abstract 4082: Epithelial-stromal interactions are altered at the earliest stages of colon cancer development

Abstract

Abstract While progression of nonmalignant colonic cells carrying somatic mutations to early malignancy is dependent upon interactions between mutated epithelium and surrounding stroma, the nature of these interactions is poorly understood. Here we report the development of an ultra-sensitive laser capture microdissection/RNA-seq approach for profiling the epithelial and stromal compartments of mutated aberrant crypt foci (ACF). ACF are the earliest detectable pre-neoplastic lesion found in human colon and were identified using high-definition endoscopy with contrast dye-spray. We focused on epithelial and stromal cells of ACF carrying somatic mutations to either KRAS, BRAF or APC, and compared these to control samples from each patient. By comparing the gene expression from each group, we identified an increase in a number of pro-inflammatory NF-κB target genes that are specific to ACF epithelium (including TIMP1, RELA and RELB). We confirmed distinct transcriptional changes associated with each somatic mutation and demonstrate that a subset of ACF display a BRAFV600E-mediated senescence-associated transcriptome, characterized by increased expression of CDKN2A (p16). Furthermore, ACF-associated stroma is transcriptionally distinct from adjacent normal stroma and genes related to immune cell infiltration and activation of fibroblasts are up-regulated. Immunofluorescence analysis confirms the abundance of activated fibroblasts in ACF stroma regardless of mutational status. These results provide new insight into the cellular interplay that occurs at the very early stages of colon cancer development, highlighting the role of activated stromal fibroblasts and inflammation. Citation Format: Allen Mo, Stephen Jackson, Kamini Varma, Alan Carpino, Charles Giardina, Thomas J. Devers, Daniel W. Rosenberg. Epithelial-stromal interactions are altered at the earliest stages of colon cancer development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4082.