Generation Of A Double Binary Transgenic Zebrafish Model To Study Myeloid Gene Regulation In Response To Melanocyte Transformation

A complex network of inflammation succeeds somatic cell transformation and malignant disease. Immune cells and their associated molecules are responsible for detecting and eliminating cancer cells as they establish themselves as the precursors of a tumour. By the time a patient has a detectable solid tumour, cancer cells have escaped the initial immune response mechanisms. To date, no model exists for studying the underlying mechanisms that govern the initial phase of the immune response when transformed cells become precursors of cancer. Here we describe the development of a double binary zebrafish model designed for exploring regulatory programming of the myeloid cells as they respond to oncogenic transformed melanocytes. A hormone-inducible binary system allows for temporal control of different Ras-oncogenes (NRasK61Q, HRasG12V, KRasG12V) expression in melanocytes, enabling analysis of melanocyte transformation and melanoma initiation. This model was coupled to binary cell-specific biotagging models allowing in vivo biotinylation and subsequent isolation of macrophage or neutrophil nuclei for regulatory profiling of their active transcriptomes. Nuclear transcriptional profiling of neutrophils, performed for the first time as they respond to the earliest precursors of melanoma in vivo, revealed an intricate landscape of regulatory factors that may promote progression to melanoma including fgf1, fgf6, cathepsin H, cathepsin L, galectin 1 and galectin 3. The model presented here provides a powerful platform to study the myeloid response to the earliest precursors of melanoma.\n\nSummary StatementWe present an innovative double binary zebrafish model for exploring the underlying regulatory mechanisms that govern the myeloid response mechanisms at the onset of melanoma.