Abstract 4949: Multimodal analysis of metals, spatial transcriptomics, and histological structures in colorectal cancer
Authors: Srivastava Aruesha , Shaik Neha , Lu Yunrui , Chan Matthew , Diallo Alos , Han Serin , Steiner Ramsey , Punshon Tracy , Jackson Brian , Vahdat Linda , Vaickus Louis , Hoopes Jack , Kolling Fred , Marotti Jonathan , Levy Joshua 
Published: March 2024

Abstract
Colorectal Cancer (CRC) accounts for nearly 10% of all cancer cases and is the second-leading cause of cancer-related deaths worldwide. The increased incidence of CRC in younger demographics underscores the need for improved screening and prognostication. These enhancements are crucial to augment staging practices which focus on accurate evaluation of local lymph node involvement and distant metastasis. Essential trace elements such as copper and iron within the tumor microenvironment (TME) present novel therapeutic strategies- e.g., copper in cell proliferation/signaling and iron in pro-tumorigenic pathways, amongst other multifaceted roles. Despite advancements in spatial imaging/sequencing for detailed mapping of elemental abundance and gene expression profiles at near-subcellular resolution, the understanding of metal signaling and transport pathways in tumors is limited. This gap highlights the need for sophisticated informatics software for data integration and analysis. We developed a computational workflow for spatial multimodal analysis of elements, genes, cell-types, and histological features, applied to a unique CRC case (pT3) as proof-of-concept. Elemental imaging at 5-micron resolution was performed using laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICPTOF-MS). The 10x Genomics Visium spatial transcriptomic (ST) CytAssist assay captured spatial variation in gene expression within 55-micron spots, with 40X H&E-stained whole slide imaging (Leica Aperio GT450). Cell type proportions within spots were determined through integration of single cell RNASeq. Regions within, around and away from tumor were annotated by a pathologist. ST and LA-ICPTOF-MS were integrated through co-registration software developed at Biomedical National Elemental Imaging Resource. Local Getis-Ord spatial statistics defined hotspots with high elemental concentration. Wilcoxon tests were used to perform differential expression analysis based on metal hotspots, followed by identification of associated biological pathways through Enrichr with Bonferroni adjustment. Preliminary findings revealed distinct trace element distributions in the TME. For instance, Copper was localized within tumor, correlating with pathways related to immune response and activation (overlap=10/89, p&lt;0.0001). Iron was found concentrated at the proliferative front of the tumor, associated with the epithelial to mesenchymal transition pathway and extracellular matrix remodeling (overlap=25/291, p&lt;0.0001), as well as with a mesenchymal phenotype (W=11.7, p&lt;0.0001), identified through cell type deconvolution. Future work will expand on these findings across multiple tissue contexts as means to capture biological processes governing tumor metastasis, recurrence and survival for biomarker discovery and therapeutics development.
Citation Format: Aruesha Srivastava, Neha Shaik, Yunrui Lu, Matthew Chan, Alos Diallo, Serin Han, Ramsey Steiner, Tracy Punshon, Brian Jackson, Linda Vahdat, Louis Vaickus, Jack Hoopes, Fred Kolling, Jonathan Marotti, Joshua Levy. Multimodal analysis of metals, spatial transcriptomics, and histological structures in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4949.