Abstract A29: Detection of ultra-rare mutations during breast stem cell tumor progression by Duplex Sequencing

Most studies have mainly investigated clonal mutations due to the high background error frequencies of conventional next generation sequencing (NGS) methods. We have established a new method termed Duplex Sequencing (DS) that detects mutations with unprecedented accuracy and enables us to detect sub-clonal and rare mutations as well as clonal mutations. Using DS, we present our first genome-wide analysis of mitochondrial (mt) DNA mutations during the transformation of human normal breast stem cells to tumorigenic cells. We used a model system to dissect sequential steps in the progression of normal stem cells to tumorigenic cells. Significant differences have been found among normal stem cells, immortal cells, and tumorigenic cells. These cells differ in putative breast cancer stem cell (CSC) populations, mtDNA copy numbers, and the frequencies and types of mutations. We found that putative CSCs and mtDNA copy numbers increase as normal stem cells become tumorigenic cells. The vast majority of mutations identified in our study are stochastic (rare mutations) and the frequency of rare mutations is lower in transformed cells than in normal stem cells. This lower rare mutation load in transformed cells induces lower scores of predicted pathogenicity in transformed cells than in normal stem cells. C>T/G>A and A>G/T>C transitions are the major mutation types in normal stem cells, while only C>T/G>A are the major mutation types in transformed cells. Using DS, we d...
Source: Molecular Cancer Research - Category: Cancer & Oncology Authors: Tags: Genomics - Sporadic and Hereditary: Poster Presentations - Proffered Abstracts Source Type: research