Chromosomal alterations during lymphatic and liver metastasis formation of colorectal cancer.

Comparative genomic hybridization (CGH) was used to screen colorectal carcinomas for chromosomal aberrations that are associated with metastatic phenotype. In total, 63 tumor specimens from 40 patients were investigated, comprising 30 primary tumors, 22 systemic metastases (12 liver, 6 brain, and 4 abdominal wall metastases) and 11 lymph node tumors. Using statistical analysis and histograms to evaluate the chromosomal imbalances, overrepresentations were detected most frequently at 20q11.2-20q13.2, 7q11.1-7q12, 13q11.2-13q14, 16p12, 19p13, 9q34, and 19q13.1-19q13.2. Deletions were prominent at 18q12-18q23, 4q27-4q28, 4p14, 5q21, 1p21-1p22, 21q21, 6q16-6q21, 3p12, 8p22-8p23, 9p21, 11q22, and 14q13-14q21. Hematogenous metastases showed more alterations than lymph node tumors, particularly more deletions at 1p, 3, 4, 5q, 10q, 14, and 21q21 and gains at 1q, 7p, 12qter, 13, 16, and 22q. Comparing liver metastases with their corresponding primary tumors, particularly deletions at 2q, 5q, 8p, 9p, 10q, and 21q21 and gains at 1q, 11, 12qter, 17q12-q21, 19, and 22q were more often observed. The analysis suggested that the different pathways of tumor dissemination are reflected by a nonrandom accumulation of chromosomal alterations with specific changes being responsible for the different characteristics of the metastatic phenotype.

Overexpression of c-erbB-2 protein correlates with chromosomal gain at the c-erbB-2 locus and patient survival in advanced colorectal carcinomas.

Overexpression of the c-erbB-2 protein (also called HER-2/neu) is observed in a variety of malignancies including colorectal cancer (CRC). In this study we aimed to evaluate the rate of c-erbB-2 overexpression in our tumor collection and to clarify its correlation with the chromosomal status at the c-erbB-2 locus in CRC. Additionally we correlated the c-erbB-2 overexpression and the chromosomal gain of 17q with patient survival. Seventy-four specimens were analyzed immunohistochemically using a polyclonal c-erbB-2 antibody (DAKO) and the staining was scored according to the Clinical Trial Assay recommendations (0-3+). Of these, 45 cases were analyzed by comparative genomic hybridization (CGH) and immunohistochemistry (IHC). Overexpression was observed in 51% of the cases (score > or = 2). Chromosomal gains at the c-erbB-2 locus were clearly correlated with overexpression of the gene (P = 0.0009). Furthermore Kaplan-Meier analysis showed that overexpression of c-erbB-2 was significantly associated with poor survival and thus could serve as a prognostic marker. We conclude that c-erbB-2 is related with tumor progression in CRC which can be observed on protein level and reflects chromosomal gain at the locus at 17q.

Incidence of chromosomal imbalances in advanced colorectal carcinomas and their metastases.

Comparative genomic hybridization (CGH) was used to screen 54 advanced colon carcinomas. i.e., 24 primary tumors and 30 metastases, for chromosomal alterations. Using a sensitive statistical method for the determination of DNA imbalances and histograms for analysis of the incidence of changes, we identified the DNA over-representation of chromosome 20q as the most common alteration being present in 100% of cases. High incidence deletions were observed on 18q21-18q23 (96%), 4q27-4q28 (96%), 4p14 (87%), 5q21 (81%), 1p21-1p22 (72%), 21q21 (74%), 6q16 (72%), 3p12 (66%), 8p24-8p21 (66%), 9p21 (64%), 11q22 (64%), and 14q13-14q21 (64%). Further frequent over-representation was found on 7q12-7q11.2 (75%), 16p11-16p12 (70%), 19p13 (70%), 9q34 (67%), 19q13 (67%), 13q34 (64%), 13q13 (64%), 17q21 (59%), 22q11 (61%), 8q24 (57%), and 1q21 (57%). Pronounced DNA gains and losses being defined as regions in which the ratio profiles exceeded the values of 1.5 and 0.5, respectively, frequently colocalized with peaks of incidence curve. The use of difference histograms for the comparison of tumor subgroups as well as case-by-case histogram for the analysis of 15 paired tumor samples identified several of the above alterations as relevant for tumor progression and metastasis formation. The study identified additional loci and delineates more precisely those that have been previously reported. For comparative purposes, we have made our primary data (ratio profiles, clinicopathological parameters, histograms) available at the interactive web site http://amba.charite.de/cgh, where the incidence of changes can be determined at individual loci and additional parameters can be applied for the analysis of our CGH results.

MACC1, a newly identified key regulator of HGF-MET signaling, predicts colon cancer metastasis.

We identified a previously undescribed gene associated with colon cancer by genome-wide expression analysis in primary and metastatic carcinomas: metastasis-associated in colon cancer-1, MACC1. MACC1 expression in tumor specimens is an independent prognostic indicator of metastasis formation and metastasis-free survival. We show that the gene encoding the hepatocyte growth factor (HGF) receptor, MET, is a transcriptional target of MACC1. MACC1 promotes proliferation, invasion and HGF-induced scattering of colon cancer cells in cell culture and tumor growth and metastasis in mouse models. These phenotypes are lost in cells expressing MACC1 mutants lacking the SH3 domain or the proline-rich motif. For clinical practice, MACC1 will be useful for the identification of poor prognosis subjects with colorectal cancer and is a promising new target for intervention in metastasis formation.

Overexpression of cyclooxygenase-2 correlates with chromosomal gain at the cyclooxygenase-2 locus and decreased patient survival in advanced colorectal carcinomas.

PURPOSE: Overexpression of cyclooxygenase-2 is observed in a variety of malignancies including colorectal cancer. However, to date, cyclooxygenase-2 expression by advanced human colorectal cancers and their metastases has been poorly characterized. This study was designed to evaluate the rate of cyclooxygenase-2 overexpression in our tumor collection and to clarify its correlation with the chromosomal status at the cyclooxygenase-2 locus in colorectal cancer. METHODS: Seventy-four specimens were analyzed immunohistochemically using a monoclonal cyclooxygenase-2 antibody. The staining was scored semiquantitatively as: -, negative; +, weak; ++, moderate; and +++, strong positive. Of these, 45 specimens were analyzed using comparative genomic hybridization and immunohistochemistry. We correlated the cyclooxygenase-2 overexpression with the chromosomal gain of 1q25.2-q25.3 and patients survival and compared primary colorectal cancers and their paired metastases at the DNA and protein level. RESULTS: Overexpression was observed in 58 percent of the cases (score > or = ++). Chromosomal gains at the cyclooxygenase-2 locus were clearly correlated with overexpression of the gene (P=0.009). Furthermore, the comparison of paired tumor samples showed additional overrepresentation in the metastases at the cyclooxygenase-2 locus, which could be confirmed by immunohistochemistry. Kaplan-Meier analysis showed that overexpression of cyclooxygenase-2 was significantly associated with poor survival and thus could serve as a prognostic marker. CONCLUSIONS: We conclude that cyclooxygenase-2 is related with tumor progression and metastasis in colorectal cancer, which can be observed on protein level, and reflects chromosomal gain at the locus at 1q25.2-q25.3.