Fig. S1. Difference in mean age and in mean tumor size among subtypes. Fig. S2. Genes effected by putative somatic Mobile Elements Insertions (MEI) events. Fig. S3. Rearrangements leading to potential fusion events. Fig. S4. Mutational hotspots in CIC (SLC25A1) and MUC16 genes. Fig. S5. Contribution of known somatic mutation signatures into mutational processes. Fig. S6. Genes effected by frequent germline alterations. Fig. S7. Association of patient's age (A) and each subtype (B) with survival. Fig. S8. Association of each type of structural variations (SVs) and overall survival. Fig. S9. CCDC58 mutation associated with worse survival.
Funding
National Institute of Dental and Craniofacial Research
NIH Office of Rare Diseases Research
Salivary Gland Tumor Biorepository
Kathryn O'Connor Research Professorship
The Center for Genetics and Genomics
Cancer Center (CORE) Support Grant NCI
Adenoid Cystic Carcinoma Research Foundation
ARTICLE ABSTRACT
Salivary gland carcinomas (SGCs) are pathologically classified into several widely diverse subtypes, of which adenoid cystic carcinoma (ACC), mucoepidermoid carcinoma (MEC), and salivary duct carcinoma (SDC) are the most commonly encountered. A comparative genetic analysis of these subtypes provides detailed information on the genetic alterations that are associated with their tumorigenesis and may lead to the identification of biomarkers to guide tumor-specific clinical trials.
Whole-genome sequencing of 58 common SGCs (20 ACCs, 20 SDCs, and 18 MECs) was performed to catalog structural variations, copy number, rearrangements, and driver mutations. Data were bioinformatically analyzed and correlated with clinicopathologic parameters, and selected targets were validated.
Novel and recurrent type–specific and shared genetic alterations were identified within and among 3 subtypes. Mutually exclusive canonical fusion and nonfusion genomic alterations were identified in both ACC and MEC. In ACCs, loss of chromosome 12q was dominant in MYB or MYBL1 fusion–positive tumors and mutations of NOTCH pathway were more common in these fusion negatives. In MECs, CRTC1-MAML2 fusion–positive tumors showed frequent BAP1 mutation, and tumors lacking this fusion were enriched with LRFN1 mutation. SDCs displayed considerable genetic instability, lacked recurrent chromosomal rearrangements, and demonstrated nonoverlapping TP53 mutation and ERBB2 amplification in a subset of tumors. Limited genetic alterations, including focal amplifications of 8q21-q23, were shared by all subtypes and were associated with poor survival.
This study delineates type-specific and shared genetic alterations that are associated with early phenotypic commitment and the biologic progression of common SGCs. These alterations, upon validation, could serve as biomarkers in tumor-specific clinical trials.
