Abstract B58: Visualization of ERK and PKA activities in the tumor microenvironment comprising of lung-metastasized 4T1 murine breast tumor cells

Abstract

Abstract Tumor microenvironment comprising of fibroblasts, endothelial cells, immune cells and tumor cells play critical roles in the tumor development. The complexities and dynamic changes of interactions among the constituting cells hampers comprehensive understanding of tumor microenvironment by conventional methods such as immunohistochemistry of tissue or biochemical analyses. Recently, intravital imaging have been providing unprecedented insight into tumor microenvironment. From the perspective of imaging, fluorescent imaging based on the principle of Förster resonance energy transfer (FRET) provides important information about cellular events that cannot be obtained by other methods. Genetically-encoded FRET biosensors have been widely used in biology to visualize the spatiotemporal dynamics of signaling molecules. Despite the increasing multitude of these biosensors, their application has been mostly limited to cultured cells with transient biosensor expression, due to difficulties in stable expression of FRET biosensors. We have recently reported the efficient generation of transgenic mouse lines expressing heritable and functional biosensors for ERK and PKA. These transgenic mice were generated by the cytoplasmic co-injection of Tol2 transposase mRNA and a circular plasmid harboring Tol2 recombination sites. Observation of these transgenic mice by two-photon excitation microscopy enabled us to visualize the activities of ERK and PKA in live tissues. Here, we report the visualization of ERK and PKA activities in 4T1 mammary tumor cells metastasized to lung tissue, which enabled us to observe effect of tumor microenvironment. We have also developed the imaging system to stabilize the live lung tissue to obtain stable images with the reduction of image blurring caused by breathing. We hereby demonstrate the utility of a three-dimensional, intravital FRET imaging technique toward understanding the mechanisms underlying tumor invasion and metastasis. Citation Format: Yuji Kamioka, Michiyuki Matsuda. Visualization of ERK and PKA activities in the tumor microenvironment comprising of lung-metastasized 4T1 murine breast tumor cells. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B58. doi:10.1158/1538-7445.CHTME14-B58