DNA computers to fight cancer

Israeli scientists have developed a range of tiny devices, which are not only able to detect cancer, but also to release drugs to treat the disease.

The work is still at test-tube stage, but scientists believe that it could lead to “nano-clinics”, which remain in the body, sensing illnesses and treating them automatically.

The research is led by Ehud Shapiro from the Weizmann Institute in Rehovot and is published in the journal ‘Nature’.

The devices, which are so small that around a trillion of them can fit into a microlitre (a millionth of a litre), are made of biological molecules – DNA, specially created synthetic DNA molecules and a naturally occurring enzyme, which cuts DNA.

They resemble chains, which consist of three main segments. The first segment senses levels of substances, which are produced by cancerous cells. It functions like a computer running through a simple algorithm. One algorithm, which the team tested, is intended to diagnose prostate cancer. It says that if levels of two messenger RNA molecules (PPAP2B and GSTP1) are lower than usual, and levels of two others (PIM1 and HPN) are elevated, there must be prostate cancer cells in the vicinity. If this analytical/computational segment "decides" that cancer is present, it tells the second segment to release the third segment, which is an anti-cancer drug - in this case, consisting of so-called anti-sense DNA. This has the effect of suppressing gene activity involved in the cancer.

Professor Shapiro has referred to the devices as ‘smart drugs’, in that they will be released and activated only at the right time and at the right location where a disease is diagnosed.

These devices have only been trialled in test-tube solutions, and several decades of further work are needed before research could begin in humans. However, scientists believe that, one day, nano-scale devices like these could be used inside our bodies to protect against or treat cancers and other diseases.

(KmcA)