Abstract 6778: Spatial analysis of genomic signatures on colorectal cancer pathogenesis using the GeoMx® Digital Spatial Profiler
Authors: Li Xiang , Zha Qinqin , Lovell Brigitte , Reed Jane , Juncker-Jensen Anna , Peters Tricia , Chandramohan Lakshmi 
Published: April 2023

Abstract
Background: The development of colorectal cancer (CRC) is a complex process, involving multiple sequential molecular aberrations that contribute to disease progression. Understanding the immunopathogenesis of CRC particularly within the spatial context of tumor microenvironment (TME) may elucidate the genomic and biological changes to improve patient prognosis for adjuvant therapies and identifying potential drug targets. However, this can be challenging, as genomic signatures from sub-cellular populations and varying levels of immune cell infiltration in TME may be lost in bulk sequencing. In this study, we used the NanoString GeoMx® Digital Spatial Profiler (DSP) to spatially select epithelial, proximal stromal and distal stromal regions of TMEs on a total of 10 FFPE samples (5 colon cancer patients and 5 healthy donor samples) and profiled up to 1,800 genes included in the Cancer Transcriptome Atlas (CTA) panel.
Methods: Selection of regions of interest (ROI) were guided by pathology assessment of H&E images and fluorescent markers (CD45, PanCK, Syto13). Tumor and stroma (proximal and distal) regions were profiled through geometric ROI selection in PanCK+ (epithelial) and CD45+ (stromal/immune) enriched areas respectively, followed by collection of indexed oligonucleotides and sequencing on NextSeq 550 Illumina instrument. Differential expression and pathways enrichment analyses was performed using R BioConductor package DESeq2 and DSP GeoMx analysis suite. A subset of samples were tested for bulk RNA expression using PanCancer IO360 panel on NanoString nCounter Flex system and data analyzed using nSolver software 3.0 and TIS algorithm App.
Results: The CTA panel is designed to profile the global immune response and all aspects of tumor microenvironment biology. From differential gene expression analysis of epithelial and distal/proximal stromal ROIs, we have identified biomarkers such as SOX9, IRAK2 and NLRP3 that are specifically upregulated in CRC samples compared to the healthy cohort. Comprehensive pathways analysis revealed an over activation of NF-kB signaling, extracellular matrix organization and interferon signaling pathways in the CRC cohort. Suppression of the NF-kB signaling pathway is a potential therapeutic approach in the treatment of colon cancer.
Conclusion: With this spatial study using GeoMx CTA panel, we have highlighted key genes and pathways involved in CRC in order to provide a much-needed understanding of the underlying mechanisms as well as immune signatures in the development of colon cancer.
Citation Format: Xiang Li, Qinqin Zha, Brigitte Lovell, Jane Reed, Anna Juncker-Jensen, Tricia Peters, Lakshmi Chandramohan. Spatial analysis of genomic signatures on colorectal cancer pathogenesis using the GeoMx® Digital Spatial Profiler. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6778.