Physical Poster + E-Poster Presentation 34th Lorne Cancer Conference 2022

Analysis of FOS transcription factor orthologue in zebrafish melanoma (#153)

khadizatul Kubra 1 , Gurveer Kaur Gaddu 1 , Faiza Basheer 1 2 , Amardeep Dhillon 1 2
  1. School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
  2. Institute of Mental Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia

Over 50% of melanomas express the oncogenic BRAFV600E kinase, which drives tumorigenesis by activating the ERK signaling pathway, a key regulator of genes governing cell proliferation, survival and differentiation. However, the transcriptional effector directing through transcriptional reprogramming downstream of ERK in melanoma are poorly defined.

 

Zebrafish represent an excellent animal model to understand the genetics and biology of melanoma and have provided key insights into somatic mutations and chromosomal abnormalities regulating melanoma development and progression. One powerful genetic strategy used in these studies is the miniCoopR system, which couples a wild-type copy of the melanocyte specification factor mitfa to a Gateway recombination cassette into which a candidate gene-of-interest can be recombined. This allows us to make constructs using open reading frames of candidate genes-of-interest that integrate into the zebrafish genome by tol2 transposase-mediated transgenesis. The effects of a gene-of-interest is then measured using melanoma-free survival curves, histological analysis and staining for cell fate markers.

 

Expression of transcription factor FOSL1 is directly induced by oncogenic BRAF-ERK signalling, suggesting it is an important effector of the pathway. Notably, exogenous expression of FOSL1 is sufficient to transform mouse melanocytes by reprogramming their gene expression patterns to mimic those induced by oncogenic BRAF, while in human melanoma cells FOSL1 has been shown to mediate BRAF-induced malignant transformation of human melanoma cells through reprogramming the expression of EMT transcription factors. Having recently established that zebrafish contain a conserved orthologues of FOSL1, this project uses the miniCoopR system to genetically test if FOSL1 is important for oncogenic BRAF-driven melanoma development and/or progression in zebrafish. This work will establish the likelihood that ERK effector pathways are conserved in zebrafish and human melanoma, thus providing a model to further dissect and test strategies to target aberrant transcriptional programming in this disease.

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