(M1330-06-32) Quantifying and Mapping ATP Distribution Within Tissues to Inform Targeted Therapeutic Strategies in Drug Development

Purpose: ATP levels, as indicators of cellular metabolic activity, offer critical insights into the viability and growth dynamics of tumor cells, presenting potential targets for therapeutic strategies. The aim of this study is to explore how ATP distribution and quantification across various mouse tumor models can optimize drug development approaches. For this purpose, we utilized Quantitative Mass Spectrometry Imaging (QMSI) to measure ATP levels in different mouse models, determining the most suitable model for targeted drug development.

Methods: Fifteen tumor biopsies from three distinct cancer models were sectioned using a cryostat and mounted on Indium-Tin-Oxide glass slides (Delta Tech, Loveland, CO, USA) or SuperFrost slides for mass spectrometry imaging (MSI) and Hematoxylin-Eosin (H&E) staining, respectively. Tissue sections on ITO slides were treated with a STOP solution to inhibit metabolization or conversion of ATP to ADO in the tissue sections. A series of ATP dilutions were prepared and applied to control tissues before the slides were coated with MALDI matrices containing ATP for normalization purposes (TM sprayer, HTX Imaging, Chapel Hill, NC, USA). The slides were then analyzed using a MALDI FTICR (SolariX and Solarix 2XR, Bruker, Bremen, Germany). Calibration curves were generated using Multimaging 1.3.2.1 software (Aliri, Loos, France). Adjacent sections on Superfrost slides were stained with Hematoxylin and Eosin, producing histological images that were then overlaid with the MSI data.

Results: ATP was consistently detected across the entire tissue sections in all three tumor models. The metabolite exhibited markedly higher concentrations in the tumor region compared to the necrotic and stromal regions (see Fig. 1). Among the models, Model 1 exhibited the highest average concentration of ATP, with an average (n=5) of 550.7 µg/g of tissue. Conversely, the lowest average concentration of ATP in the tumor region was observed in Model 2, measuring at 312.3 µg/g of tissue. This trend persisted in the necrotic regions, with Model 1 displaying the highest ATP concentration and Model 2 demonstrating the lowest (refer to Table 1).

Conclusion: Our research showcases the technical feasibility and potential applicability of utilizing ATP distribution and quantification as a dependable tool for steering therapeutic targeting in drug development. The successful utilization of Quantitative Mass Spectrometry Imaging (QMSI) methodologies to gauge ATP levels within tumor tissues underscores the accuracy and reliability of this approach. Through the integration of QMSI with advanced software-generated calibration curves, we achieved precise and quantitative evaluations of ATP concentrations across diverse tumor models. Ultimately, our findings underscore the importance of ATP distribution and quantification in facilitating targeted therapeutic approaches in drug development. By mapping the spatial distribution of ATP within tumor tissues derived from various models, we can pinpoint regions characterized by heightened metabolic activity, thus aiding in model selection and the optimization of targeted therapies.


Fig 1: Distribution of ATP in mice tumor models obtained by MALDI MSI.


Table 1: ATP quantification by MALDI-FTICR per histological region in µg/g of tissue in three tumor models (N=5 samples/model)