Abstract 1781: Whole-genome and RNA sequencing identify a novel recurrent translocation in adrenocortical carcinoma.
Authors: Demeure Michael J. , Schwartz Kaiti , Bapat Aditi , Linnehan Claire , Benson Hollie , Reiman Rebecca , Phillips Lori , Legendre Christophe , Metpally Raghu , Kurdoglu Ahmet , Craig David , Carpten John , Liang Winnie S. , Tembe Waibhav , Bussey Kimberly J. 
Published: August 2014

Adrenocortical carcinoma (ACC) is a lethal tumor of the adrenal cortex with limited treatment options. The only possibility for cure is complete surgical resection, but 50-70% of patients present with metastatic disease, precluding curative surgery. The outcome for patients with ACC has remained unchanged in the past 25 years, with the overall 5-year survival of patients undergoing surgical resection being ∼40%. Patients that present with advanced disease fare considerably worse with 5-year survival rates of 10-20%. The standard chemotherapy regimen of mitotane (the only approved agent), etoposide, doxorubicin, and cisplatin, has a response rate of 23.2%. A better understanding of pathobiology is needed to improve the treatment results for this disease.

Previous genomic studies combined with expression microarray studies have implicated lack of H19 expression coupled with IGF2 over-expression, beta-catenin activation, and loss of p53 pathway function as important events in ACC, but no single alteration has been seen in all ACC. We used a combination of whole genome sequencing, exome sequencing, and RNA-sequencing on three tumor/normal pairs from patients. Using data from spectral karyotyping of the two ACC cell lines, SW-13 and NCI-H295R, we mined the sequencing data for structural rearrangements in regions of common breakpoints. We identified

a novel recurrent translocation, t(4;8)(p16.2;p23.1) in all three tumors that was not present in the normal sequence. Using fluorescent in situ hybridization (FISH) we validated the translocation in the three tumors and both SW-13 and H295R. An additional five of five ACC scored positive for the translocation, as did three malignant non-ACC tumors (malignant pheochromocytoma, pancreatic neuroendocrine tumor, and carcinoid) suggesting that this finding has implications beyond ACC. The recurrent translocation t(4;8) (p16.2; p23.1) involves two genes of unknown function, BC042823 (uc003gho.2, IMAGE:5275587) on chromosome 4 and BC030294 (ucoo3wrb.1, IMAGE:5396854) on chromosome 8. RNA- sequencing data and RT-PCR with primers designed to both derivative chromosomes revealed transcription from both derivative chromosomes. The cDNA products were sequenced by Sanger sequencing and show partial homology to a non-coding RNA, LOC100506990, at chr8:12,338,893-12,452,929. RNA-sequencing data revealed this locus is highly transcribed in normal adrenal gland but reduced in expression in the three ACCs. In contrast to other recurrent translocations previously found in other cancers, this translocation is only present in 18-30% of the tumor nuclei scored by FISH, suggesting that it is a necessary alteration in malignant progression, but underscoring the question of how it might cooperate with events in other sub-clones to initiate tumor formation and progression.

Citation Format: Michael J. Demeure, Kaiti Schwartz, Aditi Bapat, Claire Linnehan, Hollie Benson, Rebecca Reiman, Lori Phillips, Christophe Legendre, Raghu Metpally, Ahmet Kurdoglu, David Craig, John Carpten, Winnie S. Liang, Waibhav Tembe, Kimberly J. Bussey. Whole-genome and RNA sequencing identify a novel recurrent translocation in adrenocortical carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1781. doi:10.1158/1538-7445.AM2013-1781