Scientists identify weak link in cancer cells

Electron micrograph of the surface of a cervical cancer cell Keystone

Researchers at Geneva University say they have identified a point in cancer cell development where they believe the progression of certain tumours can be stopped.

This content was published on November 29, 2006

Those behind the discovery say it should lead to the development of new "inhibitor" drugs, but warn that it could be 15-30 years before they are available.

The research, published in this week's Nature magazine, was carried out by a team led by Thanos Halazonetis, professor of molecular biology at Geneva University.

The team studied the DNA replication process of pre-cancerous and cancerous cells and found it to be very much a stop-start affair unlike that of normal cells, which replicate without interruption. DNA – or deoxyribonucleic acid – carries a cell's genetic information and is capable of self-replication.

According to Halazonetis, abnormal DNA replication activates a protein – P53 – known as a "tumour suppressor". This prevents the cells from dividing.

For example, most of the moles on our skin are pre-cancerous lesions but P53 stops them from developing into full-blown cancers known as melanoma.

The problem is that if the P53 protein fails to fulfil its role, the pre-cancerous cells will progress unchecked to the cancerous state.

Halazonetis and his team believe the key lies in preventing these cells from restarting DNA replication and spreading once the P53 process has broken down.

"If we can inhibit the restart of replication, the tumour cells [...] would die," he told swissinfo.

"Significant find"

The professor, who arrived at Geneva University from the Wistar Institute in Philadelphia earlier this year, described the discovery as "significant".

He said that now they had discovered what appeared to be a weak link in the progression of tumours, scientists could get to work on the basic science for developing a drug.

Halazonetis added that such a treatment would need to target only pre-cancerous or cancer replicating cells and not normal replicating cells such as those in bone marrow that produce blood cells.

Many current cancer therapies kill replicating cells indiscriminately, which is why patients often suffer from anaemia and hair loss.

"With time and appropriate funding we will find a way of specifically stopping the replication of cancer cells and this could work for most tumours," said Halazonetis.

"The problem is that to develop a drug you need the basic science... and this will take five to ten years. Then the pharmaceutical companies take over to develop the chemical inhibitors and that takes ten to 20 years. So we are talking 15-30 years, but at least there is light at the end of the tunnel."

swissinfo, Adam Beaumont in Geneva

In brief

The Geneva University team worked closely with colleagues at Athens University, the Danish Cancer Society based in Copenhagen, and Stockholm University.

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Key facts

According to the World Health Organization, cancer is a leading cause of death worldwide. Last year cancer accounted for 7.6 million (or 13%) of all deaths.
The biggest killers are lung (1.3 million), stomach (1 million), liver (662,000), colon (655,000) and breast (502,000).

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