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Science

World network against cancer

A study of a thousand genes highlights the contribution of the Brazilian project

During six days, from the 20th to the 25th of August, thirty specialists from two major projects that are studying the genetic origins of cancer met at the Ludwig Institute of São Paulo, where, with the help of a network of 20 computers, they discussed and compared their data with the objective of discovering disease markers. The meeting brought together researchers of the Human Cancer Genome project, an initiative between FAPESP and the São Paulo branch of the Ludwig Institute, and of the Cancer Genome Anatomy Project (CGAP), of the National Institute of Cancer of the United States. Also participating were specialists from the University of Oxford, form the UK, and from the National Institute of Bioinformation Technology of South Africa (Sanbi).

This type of event, called a jamboree (international scout congress), is an informal and prolonged working meeting, which may extend for days. A concentrated effort, with researchers from various countries, with the objective of bringing about an integrated vision on a particular question. In the area of genomics, there were recently two jamborees , one about the fruit fly, Drosophila melanogaster, and the other about the mouse (Mus musculus).

On the meeting about cancer, the researchers centered their analysis on the 2.7 million expressed sequences (gene fragments), extracted from human tissue with tumors, 1.5 million coming from the work of CGAP and 1.2 million from the Brazilian project. Besides the discussions on these sequences, the researchers studied the standard of expression and mutation of a group of one thousand genes related to tumors. “Starting out from these discussions, we want to produce an article for a scientific magazine”, says Andrew Simpson of the Ludwig Institute and the coordinator of the Human Cancer Genome Project.

For Robert Strausberg, the director of CGAP, a joint effort by the Brazilians and North Americans, responsible for the most productive projects in the area of the cancer genome, could accelerate the search for new forms of diagnosis and treatment of various forms of the disease. The optimism is justified. The two groups use distinct but complementary methodologies in the task of looking for fragments of the genes linked to cancer.

Methods and positions
The Human Cancer Genome Project uses the Orestes technique, created in Brazil, which extracts information above all from the codifying (expressive) regions of the genetic code, which are going to provide the instruments for the production of proteins. Generally situated in the central part of the genes, these regions represent close to 3% of the human genome, which is composed of 3 billion pairs of bases. The CGAP uses techniques that obtain information from the extremities of the genes.

The dream of every scientist who studies the genetic causes of cancer is to find marker for each type of cancer, to discover alterations in the genome that would be the trademark of various forms of the disease. This is not easy. After all, one is speaking of one of the most mutant diseases known. For example, some forms of cancer are localized and of slow progress. Others spread through the organism at an impressive speed. In spite of all of the advances in medicine, a precise and precocious diagnosis is not always possible.

In the search for cancer indicators or markers, one of the research tools is DNA chips. With the help of these arrangements, which allow for the placement of thousands of cloned genes on the one sheet, the researchers can manage to discover which of them are used in a determined situation. Thus, for example, we can verify which genes act on the healthy tissue of the lung and which express themselves in the cells of this organ taken over by tumors. The South African Winston Hide, the director of Sanbi, who participated in the São Paulo meeting, believes that close to one third of the estimated 30,000 human genes are related to cancer.

Major league
For Hide, the contribution of the Brazilian project, an investment of some US$ 20 million, divided half and half by FAPESP and the Ludwig Institute, has been decisive, greater even than the contribution from the CGAP. The quantity of data provided by the CGAP is greater, but the information supplied by the Human Cancer Genome Project is of better quality. “I believe that 70% of the knowledge of the world about the expressed cancer genes comes from Brazil and only 30% for the United States”, says Hide. “The jamboree was very interesting, since, for the first time, we had the chance to have an integrated vision of the cancer genome.”

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