TP53 mutation is enriched in colorectal cancer liver metastasis in the context of polyclonal seeding

Cancer metastasis accounts for the majority of cancer motility burden. For colorectal cancer (CRC), the liver is the most common site of distant metastasis. It is still little known that cancer genomic mutations, which are a cell-intrinsic and heritable property, are enriched in CRC liver metastasis. Here, we try to answer the question in the context of polyclonal seeding. In this study, we sequenced 18 pairs of colorectal cancer primary tumors and their matched liver metastasis samples. Together with public available sequencing data, we compared the mutations in 113 primary and metastasis pairs. The TP53 mutation variant allele frequency (VAF) was significantly increased in metastasis compared to the paired primary tumor, although most of the frequently observed mutations in liver metastasis foci were concordant with their matched CRC primary tumors. The results support late metastasis and polyclonal seeding. Consequently, we quantitatively compared the intratumor heterogeneity (ITH) between primary and metastasis tumors, and with the help of in silico metastasis simulation, we inferred that more than 10 cells take part in the CRC liver metastasis.