NEW YORK (Reuters Health) - Investigators from Taiwan say they have identified distinct genomic and chromosomal aberrations that increase the likelihood that primary colorectal carcinomas will spread to the lungs.
They have observed that primary cancers containing more genomic lesions, especially losses on chromosome arm 8p, are more likely to metastasize to the lungs, and that the loss of chromosome 4q may play an important supporting role in pulmonary dissemination.
“Our results provide important information for the prognostic evaluation of primary colorectal cancers,” Dr. Jeng-Kai Jiang from National Yang-Ming University and colleagues write in the May issue of the journal Genes, Chromosomes and Cancer.
They used comparative genomic hybridization to analyze gene copy number changes and the clonality relationship between primary colorectal cancers and their pulmonary metastases.
They obtained 18 paired samples of primary colorectal cancer tissue and their corresponding pulmonary metastases from 18 patients who had undergone two consecutive surgeries for both malignancies.
The overall abnormality profiles were similar for the primary tumors and their lung metastases, with frequent gains observed on chromosome arms 20q, 8p, 13q, and 7q, and frequent losses on 18q, 8p, and 18p.
The pulmonary metastases, however, contained more genomic abnormalities compared with the primary colorectal tumors.
Among all the genomic changes, losses on chromosome arms 8p and 4q were singled out as the two most important genomic changes associated with pulmonary metastatic dissemination from colorectal cancer in this study.
These observations support previous studies, which have tied loss of 8p and 4qwith a poor prognosis in colorectal cancer.
Clonality studies showed that 56% of paired samples showed a high-degree of clonality, indicating that they likely originated from the same clone and/or not many additional chromosomal changes had occurred in the metastases -- except for 4q loss, which was observed in 60% of metastases and only 10% of primary tumors.
The primary tumors exhibiting high clonality also carried more genomic aberrations, especially 8p loss, than did the primary tumors with low clonality.
Of note, 8p21-p23 was the most common region involved in the current study, which supports prior reports that this is a site of putative tumor-suppressor genes and suggests that this is a good target for positional cloning efforts to define the underlying genetic defect, the authors suggest.
Source: Genes Chromosomes Cancer 2005;43:25-36. [ Google search on this article ]
MeSH Headings:Biological Sciences: Biology: Chromosome Aberrations: Cytogenetics: Genetics: Biological SciencesCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
