Abstract 1507: Involvement of GABAergic signaling in enhanced tumor cell invasion in a mechanically dynamic tumor microenvironment
Authors: Strelez Carly , Perez Rachel , Chlystek John S. , Cherry Christopher , Haliday Bethany , Yoon Ah Young , Shah Curran , Sun Ren X. , Lau Roy , Schatz Aaron , Neman Josh , Josef-Lenz Heinz , Katz Jonathan , Mumenthaler Shannon M. 
Published: March 2024

Abstract
Metastasis is a major contributor to cancer morbidity and mortality. However, studying this complex, multi-step, multi-organ process is challenging. There is a pressing need to dissect the contributions of the tumor microenvironment (TME) on this process in a controlled and precise manner. Fortunately, the utilization of microfluidic “organs-on-chips” (OOC) in cancer research is facilitating such investigations. Moreover, by combining organoids and organs-on-chips we can enhance the progress of these studies in a patient specific manner. In this study, we have developed a cancer-on-chip model aimed at investigating early metastatic spread within the colon milieu. To achieve this, we employ colorectal cancer (CRC) cell lines as well as patient-derived CRC organoids chosen from our biorepository to encompass diverse representations across race/ethnicity, sex, and mutational profiles. The tumor cells are introduced into the upper chamber of the OOC model, while human microvascular endothelial cells (HIMECs) are introduced into the lower chamber to establish a tube-like structure resembling a blood vessel. These two chambers are separated by a porous membrane, and the chip is flanked by vacuum chambers to introduce stretch-like motions, simulating peristalsis in the gastrointestinal track.
Creating a mechanically dynamic microenvironment facilitates the exploration of neurotransmitters and their impact on tumor cell behavior. Recent studies have suggested that tumor cells may exploit physiological processes, such as neurotransmitter signaling, to their benefit. By utilizing mass spectrometry-based metabolomics we detected dynamic and patient organoid-specific changes in neurotransmitter levels (i.e., serotonin, aspartate, glutamate, γ-aminobutyric acid (GABA)) in the effluent of our CRC-on-chip model. Coupled with live-cell imaging, we discovered tumor cell-derived GABA, a major inhibitory neurotransmitter, serves as an energy source for supporting tumor cell intravasation. This finding was most pronounced in KRAS-mutant tumor cells and further supported by analysis of CRC patient samples from The Cancer Genome Atlas (TCGA) database. We were able to reverse the GABA-mediated invasion effect by inhibiting 4-aminobutyrate aminotransferase (ABAT), the enzyme responsible for GABA catabolism. In summary, our cancer-on-chip model holds promise for exploring various aspects of the metastatic process and uncovering potential therapeutic targets, such as neurotransmitters.
Citation Format: Carly Strelez, Rachel Perez, John S. Chlystek, Christopher Cherry, Bethany Haliday, Ah Young Yoon, Curran Shah, Ren X. Sun, Roy Lau, Aaron Schatz, Josh Neman, Heinz Josef-Lenz, Jonathan Katz, Shannon M. Mumenthaler. Involvement of GABAergic signaling in enhanced tumor cell invasion in a mechanically dynamic tumor microenvironment [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 1507.