High-resolution Genotyping of Chromosome 8 in Colon Adenocarcinomas Reveals Recurrent Break Point But No Gene Mutation in the 8p21 Region:

Genomic profiling of sporadic liver metastatic colorectal cancer

Sporadic colorectal cancer (sCRC) is the third leading cause of cancer death in the Western world. Approximately, a quarter of sCRC patients present metastatic dissemination at the moment of diagnosis, the liver being the most frequently affected organ. Additionally, this group of CRC patients is characterized by a worse prognosis. In the last decades, significant technological developments for genome analysis have fostered the identification and characterization of genetic alterations involved in the pathogenesis of sCRC. However, genetic alterations involved in the metastatic process through which tumor cells are able to colonize other tissues with a different microenvironment, still remain to be fully identified. Here, we review current knowledge about the most relevant genomic alterations involved in the liver metastatic process of sCRC, including detailed information about the genetic profile of primary colorectal tumors vs. their paired liver metastases.

Proteome atlas of human chromosome 8 and its multiple 8p deficiencies in tumorigenesis of the stomach, colon, and liver

Chromosome 8, a medium-length euchromatic unit in humans that has an extraordinarily high mutation rate, can be detected not only in evolution but also in multiple mutant diseases, such as tumorigenesis, and further invasion/metastasis. The Chromosome-Centric Human Proteome Project of China systematically profiles the proteomes of three digestive organs (i.e., stomach, colon, and liver) and their corresponding carcinoma tissues/cell lines according to a chromosome organizational roadmap. By rigorous standards, we have identified 271 (38.7%), 330 (47.1%), and 325 (46.4%) of 701 chromosome 8-coded proteins from stomach, colon, and liver samples, respectively, in Swiss-Prot and observed a total coverage rate of up to 58.9% by 413 identified proteins. Using large-scale label-free proteome quantitation, we also found some 8p deficiencies, such as the presence of 8p21-p23 in tumorigenesis of the above-described digestive organs, which is in good agreement with previous reports. To our best knowledge, this is the first study to have verified these 8p deficiencies at the proteome level, complementing genome and transcriptome data.

Towards a "Lyon molecular signature" to individualize the treatment of rectal cancer. Prognostic analysis of a prospective cohort of 94 rectal cancers T1-2-3 Nx MO to be the basis of a molecular signature

PURPOSE

In 1998 a translational research was initiated in Lyon aiming at identifying a prognostic "biomolecular signature" in rectal cancer. This paper presents the clinical outcome of the patients included in this study.

PATIENTS AND METHODS

A total of 94 patients were included between 1998 and 2001. A staging with rectoscopy and biopsies was performed before treatment. In case of surgery, the operative specimen was analysed to evaluate the pathological response. There were two types of treatment: neoadjuvant radiotherapy (with or without concurrent chemotherapy) followed by surgery (76 cases) and radiotherapy alone with 'contactherapy' often associated with external beam radiotherapy (18 patients).

RESULTS

The patients had a mean age of 63years. Stage was T1: 4, T2: 24, T3: 65 and T4: 1. The overall survival of the 94 patients was 62% at 8years with a rate of distant metastases of 29%. Rate of local recurrence at 8years was 6% in the neoadjuvant group and 16% in the radiotherapy group with an overall 8years survival in both groups respectively: 64% and 53%. There was a trend towards more metastases in cT3, tumour diameter above 4cm, circumferential extension. There was a significant increase in the risk of metastases for ypT3, ypN1-2 and Dworak score 1-2-3. In multivariate analysis ypT3 was significantly associated with a high rate of metastases (55%; P=0.0003).

CONCLUSION

The rate of distant metastases is a major prognostic factor. These clinical results will serve as the base line to identify a "biomolecular signature" which could complement the TN(M) classification.

Molecular pathways in colorectal cancer

Colorectal cancer (CRC) is the second most common newly diagnosed cancer and accounts for the second highest number of cancer related deaths in Australia, the third worldwide and of increasing importance in Asia. It arises through cumulative effects of inherited genetic predispositions and environmental factors. Genomic instability is an integral part in the transformation of normal colonic or rectal mucosa into carcinoma. Three molecular pathways have been identified: these are the chromosomal instability (CIN), the microsatellite instability (MSI), and the CpG Island Methylator Phenotype (CIMP) pathways. These pathways are not mutually exclusive, with some tumors exhibiting features of multiple pathways. Germline mutations are responsible for hereditary CRC syndromes (accounting for less than 5% of all CRC) while a stepwise accumulation of genetic and epigenetic alterations results in sporadic CRC. This review aims to discuss the genetic basis of hereditary CRC and the different pathways involved in the process of colorectal carcinogenesis.

A cluster of cooperating tumor-suppressor gene candidates in chromosomal deletions

The large chromosomal deletions frequently observed in cancer genomes are often thought to arise as a "two-hit" mechanism in the process of tumor-suppressor gene (TSG) inactivation. Using a murine model system of hepatocellular carcinoma (HCC) and in vivo RNAi, we test an alternative hypothesis, that such deletions can arise from selective pressure to attenuate the activity of multiple genes. By targeting the mouse orthologs of genes frequently deleted on human 8p22 and adjacent regions, which are lost in approximately half of several other major epithelial cancers, we provide evidence suggesting that multiple genes on chromosome 8p can cooperatively inhibit tumorigenesis in mice, and that their cosuppression can synergistically promote tumor growth. In addition, in human HCC patients, the combined down-regulation of functionally validated 8p TSGs is associated with poor survival, in contrast to the down-regulation of any individual gene. Our data imply that large cancer-associated deletions can produce phenotypes distinct from those arising through loss of a single TSG, and as such should be considered and studied as distinct mutational events.

[Cellular and molecular deregulations driving the metastatic phenotype]

Cancerogenesis is initiated by DNA instability that induces modifications in stem cells. Regulation is organ specific and depends on morphogenetic factors. DNA instability is alternatively related to chromosomal aberrations or DNA replication errors. Chromosomal instability is the most frequent characteristics of colon adenocarcinoma, and is observed in distant metastatic foci. It is associated with somatic APC mutations that deregulates the WNT pathway. Position of the mutations within the coding sequence are essential for the cell migration capacities thus for stem cell metastasis ability. After this step the new morphogenic program is able induce expansion in the host organ.