Supplementary Fig. S5. Validation of redundant APC mutations. A, For one case (CRC2), two redundant APC mutations are validated by Sanger sequencing. One nonsense mutation (C>T; left) and one frameshift indel (AG>A; right) are shown for seven regional biopsies for the given case. For one primary case (CRC2-P1), the nonsense mutation is not observed, consistent with the metastasis-clonal presentation of this mutation. B, The copy number changes of the entire chromosome 5 are shown for seven regional biopsies. Entire loss of chromosome 5 is observed for CRC-P1. APC locus is incidated with a red dotted line.
ARTICLE ABSTRACT
Purpose: The intratumoral heterogeneity (ITH) and the evolution of genomic architectures associated with the development of distant metastases are not well understood in colorectal cancers.Experimental Design: We performed multiregion biopsies of primary and liver metastatic regions from five colorectal cancers with whole-exome sequencing and copy number profiling.Results: In addition to a substantial level of genetic ITH, multiregion genetic profiling identifies the subclonal mutational architecture, leading to the region-based or spatial categorization of somatic mutations and the inference of intratumoral evolutionary history of cancers. The universal mutations (those observed in all the regional biopsies) are enriched in known cancer genes such as APC and TP53 with distinct mutational spectra compared with biopsy- or region-specific mutations, suggesting that major operative mutational mechanisms and their selective pressures are not constant across the metastatic progression. The phylogenies inferred from genomic data show branching evolutionary patterns where some primary biopsies are often segregated with metastastic lesions. Our analyses also revealed that copy number changes such as the chromosomal gains of c-MYC and chromothripsis can be region specific and the potential source of genetic ITH.Conclusions: Our data show that the genetic ITH is prevalent in colorectal cancer serving as a potential driving force to generate metastasis-initiating clones and also as a means to infer the intratumoral evolutionary history of cancers. The paucity of recurrent metastasis-clonal events suggests that colorectal cancer distant metastases may not follow a uniform course of genomic evolution, which should be considered in the genetic diagnosis and the selection of therapeutic targets for the advanced colorectal cancer. Clin Cancer Res; 21(19); 4461–72. ©2015 AACR.
