De Paolo Raffaella, Sarti Samanta, Bernardi Sara, Cucco Francesco, Tavosanis Andrea, Pitto Letizia, Poliseno Laura
Institute of Clinical Physiology, CNR, Pisa, Italy.
Oncogenomics Unit, Core Research Laboratory (CRL), ISPRO, Via Moruzzi 1, 56124, Pisa, Italy.
Cell Biosci. 2023 Jul 1;13(1):121. doi: 10.1186/s13578-023-01064-w.
BRAFV600E comes as two main splicing variants. The well-studied ref isoform and the recently discovered X1 isoform are co-expressed in cancer cells and differ in terms of 3'UTR length and sequence, as well as C-term protein sequence. Here, we use a melanoma model in zebrafish to study the role played by each isoform in larval pigmentation, nevi formation, and their progression into melanoma tumours. We show that both BRAFV600E-ref and BRAFV600E-X1 proteins promote larval pigmentation and nevi formation, while melanoma-free survival curves performed in adult fish indicate that BRAFV600E-ref protein is a much stronger melanoma driver that BRAFV600E-X1 protein. Crucially, we also show that the presence of the 3'UTR suppresses the effect of ref protein. Our data highlight the necessity to undertake a systematic study of BRAFV600E isoforms, in order to uncover the full spectrum of their kinase-(in)dependent and coding-(in)dependent functions, hence to develop more informed strategies for therapeutic targeting.
BRAFV600E主要以两种剪接变体形式存在。研究充分的ref异构体和最近发现的X1异构体在癌细胞中共表达，它们在3'非翻译区（3'UTR）的长度和序列以及C端蛋白质序列方面存在差异。在这里，我们利用斑马鱼黑色素瘤模型来研究每种异构体在幼虫色素沉着、痣形成以及它们发展成黑色素瘤肿瘤过程中所起的作用。我们发现，BRAFV600E-ref和BRAFV600E-X1蛋白都能促进幼虫色素沉着和痣形成，而在成年鱼中进行的无黑色素瘤生存曲线表明，BRAFV600E-ref蛋白比BRAFV600E-X1蛋白是更强的黑色素瘤驱动因子。至关重要的是，我们还表明3'UTR的存在会抑制ref蛋白的作用。我们的数据强调了对BRAFV600E异构体进行系统研究的必要性，以便揭示其激酶依赖性和编码依赖性功能的全貌，从而制定更明智的治疗靶向策略。
