Proteogenomics analysis unveils a novel TFG-RET gene fusion and druggable targets in papillary thyroid carcinomas

ABSTRACT: Papillary thyroid cancer (PTC) is the most common type of endocrine malignancy. From a set of PTC patients whose tumor did not harbour any BRAF or RAS mutations, a 35 years old male patient’s normal, primary tumor and lymph node (LN) metastatic tissues was subjected to genomics and proteomics analysis. By RNA-seq analysis, we identified a novel RET rearrangement involving exons 1-4 from the 5’ end of the Trk fused Gene (TFG) fused to the 3’ end of RET tyrosine kinase leading to a TFG-RET fusion which transforms immortalized human thyroid cells in a kinase dependent manner. Further, TFG-RET oncogene oligomerises in a PB1 domain dependent manner and consistently, mutation of the oligomerisation interface led to the inhibition of RET-mediated oncogenic transformation. Quantitative proteomic analysis of the same samples revealed the upregulation of proteins involved in the ubiquitination machinery including HECT carrying E3 Ubiquitin ligase HUWE1 and DUBs like USP9X and UBP7 in the tumor and LN metastatic lesions. We further identify that expression of TFG-RET led to the upregulation of HUWE1. Further, in a cohort of PTC patients, we observed higher expression of HUWE1, USP9X and USP7 in the tumor and metastatic lesions, when compared to the matched normal tissue. Transient knockdown of HUWE1, USP9X and USP7 affected viability and proliferation of TFG-RET transformed cells. Consistently, inhibition of RET, HUWE1 and DUBs by small molecule inhibitors significantly reduced RET-mediated oncogenesis. Apart from unveiling a novel oncogenic RET fusion in PTCs, our data may open a novel avenue of targeting ubiquitin signaling machinery in human PTCs.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Malte Sielaff  

LAB HEAD: Stefan Tenzer

PROVIDER: PXD016739 | Pride | 2020-04-02

REPOSITORIES: Pride