Organ specific microenvironmental regulation of metastasis

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

Cancer arises from the malignant transformation of normal tissue, a process influenced by cumulative genetic, environmental, and epigenetic changes. In many cases, tumor cells detach from the primary site and spread through the circulatory system, forming metastatic lesions in distant organs. This metastatic stage is the most life-threatening aspect of the disease, with approximately 90% of patients dying within five years of the detection of these secondary tumors. Targeted therapies for metastatic disease face challenges due to patient relapse and drug resistance. While combinatorial treatments, such as immunotherapy, which harnesses the patient's immune system to fight cancer, have shown promise with durable and curative responses, individual patient outcomes vary. Some patients do not respond, or they develop resistance, partly because treatment efficacy differs by organ site. A more profound understanding of patient-to-patient variability is also essential. We tackle these crucial needs by utilizing zebrafish and 3D organoids to evaluate both intra-patient and inter-patient heterogeneity. The zebrafish model is a fully immunocompetent system that enables the study of the adaptive immune system. Zebrafish genes share sequence similarities with human genes, implying shared functions of T cells. Its small size allows for simultaneous imaging of multiple organs. In this cycle, we also demonstrated the utility of the zebrafish as a model that effectively recapitulates critical aspects of human disease. This system offers the flexibility to tune genetic factors, which allows us to link measured mechanical values to underlying biological mechanisms. This is crucial for defining a predictive biomarker. Our research utilizes optical techniques in pre-clinical models to investigate the role of mechanical signatures in tumor outgrowth and treatment responses. Our primary objective is to identify parameters that can: a) Prevents the emergence of metastatic lesions. b) Provide a mechanism to enhance treatment response in non-responders to targeted therapies. Our earlier research identified blood vessels as key regulators of organ targeting and extravasation. Specifically, our proteomic analysis of brain- and bone marrow-seeking clones revealed higher levels of unconventional Myosin 1b protein in brain-targeting clones. Myosin 1b is known to mechanically link the membrane to the actin cytoskeleton, thereby significantly influencing actin architecture by altering mesh-size or cortical thickness, and consequently cortical contractility. Silencing the Myosin 1b gene redirected brain-targeting cells toward the more chaotic bone marrow niche. This finding has since been confirmed in mice further supporting the utility of the zebrafish model for screening proteins involved in organotropism. We are undergoing continued studies to elucidate the mechanism by which Myosin 1b regulates brain tropism in both mice and zebrafish. However, to move these exciting findings into the realm into understanding the mechanisms that regulate therapeutic efficacy required that we provided an innovative platform. Our key findings are summarized below: a) Instrumentation development: Our innovative Zebrafish Intubation Chamber addresses the challenge of long-term, multi-day imaging in adult zebrafish, a feat previously difficult due to their intolerance of sustained immobilization. This portable device facilitates consecutive imaging over several hours and repeated measurements over multiple days without adverse effects, making it ideal for longitudinal studies. This system, currently filed as a US Patent, allows us to visualize and track individual cancer cells, monitor immune responses, and perform multiplexed analyses to determine cellular metabolic and mechanical properties. This comprehensive data will help us assign a signature to predict therapeutic responses. b) Humanized cancer in zebrafish For melanoma induction in specific zebrafish locations, we utilized a human BRAFV600E linked to a red fluorescent protein, driven by a melanocyte-specific reporter. This was introduced into an immune-competent transgenic line with labeled immune cells, including T cells, macrophages, B cells, and neutrophils. Within seven weeks post-injection, we observed systematic development of primary melanomas and metastatic disease. These models are crucial for understanding the systemic immune response that is needed to mount anti-tumor killing potential. This is needed especially for improvement of personalized medicine. c) Organ-specific T cell behavior: Our research has revealed significant differences in the way immune cells, particularly T cells, infiltrate and migrate within various organs. This organ-specific behavior suggests unique microenvironmental cues and cellular interactions that govern immune cell dynamics. We are currently conducting in-depth investigations into these distinct patterns of infiltration and migration to understand the underlying mechanisms. The goal of this research is to leverage this understanding to enhance the anti-tumor killing potential of T cells, potentially through targeted therapeutic interventions that exploit these organ-specific characteristics to improve immune cell delivery and function within tumor site.