These findings could be used in clinical practice to complement clinical, biochemical and genetic markers for better treatment of patients with colorectal cancer.

A research group led by Sandrine Imbeaud from the CNRS and Pierre and Marie Curie University, Villejuif, France, used microarrays to analyse the gene-expression patterns of samples from colon tumours and liver metastases collected from 13 patients with colorectal cancer. The microarray analyses were carried out before the patients were treated with combined chemotherapy of folinic acid, 5-fluorouracil and irinotecan.

Imbeaud and colleagues identified 679 genes that were differently expressed in patients who subsequently responded well to chemotherapy compared with patients who were resistant to the therapy. The results were validated by RT-PCR analysis, which confirmed the differential expression of 22 genes selected from the list. The findings were also confirmed by RT-PCR analysis of colon and liver tumour samples collected from two additional patients.

The authors were able to integrate their findings into global and interconnected molecular networks that characterise resistance in patients with colorectal cancer before they are exposed to chemotherapy. They conclude that knowledge of these networks could potentially be used to improve diagnosis and treatment of patients with colorectal cancer.

genomebiology/

Ann Van Den Bogaert and her colleagues from the research group of Jurgen Del-Favero have also been studying the role of TPH2 in the development of depression and manic depression. They have conducted a genetic study in which they compared the variation in the TPH2 gene between patients with depression and healthy individuals. The DNA of two random individuals are 99.9% identical - the 0.1% that is different contains the genetic variation that can originate disorders.

In collaboration with the Swedish research group under the direction of Rolf Adolfsson and Karl-Fredrik Norrback, the researchers studied the DNA of hundreds of Swedish patients with depression and manic depression and that of healthy control subjects. By comparing the genetic variations between the patients and healthy individuals, they have shown that in this Swedish population TPH2 is involved in the development of depression and manic depression.

Thus, their research brings us a step closer to a better understanding of these psychiatric disorders.

vib.be