Adenoid Cystic Carcinoma (ACC) is the second most frequent malignancy of the minor and major salivary glands and has poor long-term prognosis. Molecular studies of ACC tumors have been complicated by the relative rarity of the tumors, differences in diagnosis and characterization, and the lack of bona fide ACC cell lines. A large majority of ACC tumors contain a recurrent t(6;9) translocation which fuses the MYB proto- oncogene on chromosome 6q to the NFIB gene on chromosome 9p. The translocations have multiple effects: leading to the expression of truncated, oncogenic forms of the c-Myb transcription factor and juxtaposing the MYB gene next to tissue specific enhancers that lead to overexpression in ACC tumors. The major challenge in studying ACC tumors has been the need to perform detailed molecular characterizations on rare tumor samples that are old enough to have clinical outcome information. To address that challenge, we developed and optimized innovative RNA-seq methods to analyze RNA derived from archival Formaldehyde-Fixed, Paraffin-Embedded (FFPE) ACC tumor samples, which allowed us to perform in-depth transcriptome analyses on these rare tumor samples. Our efforts led to the identification of novel, recurrent fusions involving both MYB and the related MYBL1 oncogene, which encodes the A-Myb transcription factor. We uncovered new insights into the mechanisms of activation of these genes in ACC tumors and characterized the gene expression profiles of ACC tumors and how they are related to MYB and MYBL1 oncogene expression. These findings put us in a unique position to investigate the mechanisms leading to ACC tumors and to identify the important regulators and potential therapeutic targets in ACC tumors. Our results lead us to hypothesize that salivary gland ACC tumors are caused by mutated MYB or MYBL1 oncogenes overexpressed due to regulation by tissue-specific enhancers, resulting in the induction of a characteristic, ACC-specific gene expression program. In this revised renewal application, we will build on the studies that we have completed and make use of the extensive RNA-seq data that we have generated for ACC tumor samples. We will focus on performing extensive and in-depth bioinformatics analyses of the RNA-seq data and on performing molecular validations to gain insights into the mechanisms that lead to ACC tumors. We will also investigate the mechanisms that lead to overexpression of the MYB and MYBL1 oncogenes in ACC tumors, with the goal of identifying new therapeutic targets. We have assembled an interactive team of investigators with expertise in molecular biology, genomics, bioinformatics, biostatistics and computational methods who will focus on these aims to answer key questions about the biology of these devastating tumors.

Public Health Relevance

This project focuses on the analysis of the molecular biology and regulatory processes at work in salivary gland Adenoid Cystic Carcinoma, by employing innovative RNA-sequencing methods. This approach will allow us to perform detailed molecular studies of gene expression and regulation, even in these rare tumor samples, which should lead to new options for the development of therapeutic strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
2R01DE023222-05A1
Application #
9380535
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Wang, Chiayeng
Project Start
2012-09-10
Project End
2022-08-31
Budget Start
2017-09-01
Budget End
2018-08-31
Support Year
5
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of New Mexico Health Sciences Center
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
829868723
City
Albuquerque
State
NM
Country
United States
Zip Code
87131
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Brayer, Kathryn J; Frerich, Candace A; Kang, Huining et al. (2016) Recurrent Fusions in MYB and MYBL1 Define a Common, Transcription Factor-Driven Oncogenic Pathway in Salivary Gland Adenoid Cystic Carcinoma. Cancer Discov 6:176-87
George, Olivia L; Ness, Scott A (2014) Situational awareness: regulation of the myb transcription factor in differentiation, the cell cycle and oncogenesis. Cancers (Basel) 6:2049-71