Differences in 20q13.2 copy number between colorectal cancers with and without liver metastasis

Abstract

Frequent gains of 20q have been identified recently in many neoplasias, including breast, bladder, ovarian, pancreatic, and colon cancers. A high level of 20q13.2 amplification is associated with poor prognosis in breast cancer. We investigated the copy number of the 20q13.2 region including the ZNF217 oncogene in 17 nonmetastatic colorectal cancers (CRCs), 18 primary CRC tumors with liver metastasis, and 18 metastatic lesions by two-color fluorescence in situ hybridization to evaluate the significance of an increased copy number of 20q13.2 in CRC, especially in those cases with liver metastasis. The frequency of increased relative copy number of the 20q13.2 region was higher in primary and liver metastatic lesions of CRC than in CRC lesions without liver metastasis. In particular, a high-level increase (>3.0-fold) in the relative copy number of 20q13.2 was observed in 2 of 18 (11%) primary CRC lesions with liver metastasis, 7 of 18 (39%) liver metastatic lesions, and in none of the cases of primary CRC without liver metastasis. The absolute and relative copy number of chromosome 20q13.2 was higher in CRCs with metastasis than in CRCs without metastasis. The percentage of cells with high-level 20q13.2 amplification was also higher in both lesions with metastasis per specimen than without metastasis. Our results suggest that the level of 20q13.2 amplification correlates with the metastatic potential and tumor progression of CRC. The results also suggest that 20q13.2 amplification with ZNF217 is associated with increased metastatic potential.