Abstract 1281: MALDI imaging mass spectrometry of three-dimensional cell culture systems

Abstract

Abstract 3D cell cultures have increased complexity compared to simple monolayer and suspension cultures, recapitulating the cellular architecture in the body. For example, many colon cancer cell lines form rounded heterogeneous spheroid structures that mimic the pathophysiological properties of tumors when grown under appropriate cell culture conditions. Classical imaging methodologies, like immunohistochemistry, are commonly used to examine the distribution of specific species within the spheroids. However, there is a need for an unbiased discovery-based methodology that would allow examination of protein/peptide distributions in 3D culture systems, without a need for prior knowledge of the analytes. We have developed MALDI imaging mass spectrometry protocols to examine protein distributions in 3D cultures models. Using the HCT 116 colon carcinoma cell line, we have grown spheroids measuring 1 mm in diameter for MALDI IMS imaging. We detect changes in the spatial distribution of proteins across the spheroids by IMS. While most proteins are distributed across the structures, some are localized to either the proliferative outer rim of the spheroids or to the central necrotic core. We are now expanding our studies to map the changes in protein distribution that accompany knockdown of E-cadherin (CDH1). We are inserting inducible shRNAs targeting CDH1 into HCT 116 cells. Once our cells stably express the shRNAs, we will grow spheroids and then trigger knockdown of CDH1 expression. We will map changes in protein expression over a time course using the MALDI imaging mass spectrometry protocols we have developed. As CDH1 is a critical component of cell-cell junctions, we anticipate that its reduction will trigger phenotypic changes in the spheroid structures. In addition, we expect to see a shift in transcriptional activity that correlates with activation of the Epithelial-Mesenchymal Transition. Our unbiased protein mapping technology enables us to examine previously observed protein changes that result from CDH1 reduction. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1281. doi:1538-7445.AM2012-1281