Cancer cells are soft

A nano-scale tool that distinguishes soft cancerous cells from stiffer normal ones could save lives by making it easier to diagnose cancer, according to a new study.

Using atomic force microscopes, a team of US scientists showed for the first time that the surface of living cancer cells were more than 70 percent softer than their healthy counterparts.

This measurable difference in elasticity held true across lung, breast and pancreatic cancers, and could provide a powerful means of detecting malignant cells that might otherwise escape notice, said the study, published in the British journal Nature Nanotechnology.

Currently, pathologists examine surgically-removed tissue by placing stained, thinly-sliced sections on a glass slide and looking at them under a microscope for signs of the disease.

Another type of test for differentiating cancerous and normal cells uses antibodies to pinpoint certain proteins.

Current tests imperfect
"However, this complex process of cancer diagnosis is not always 100 percent accurate because normal cells can sometimes look like cancerous cells," said MIT scientist Subra Suresh in a commentary, also published in Nature.

The frequency of diagnostic error for patients who have lung cancer may be as high as 15 percent due to sampling errors or faulty interpretation, earlier studies have shown.

Combining existing methods with the new technique, however, could help reduce this margin of error.

In experiments conducted at the University of California in Los Angeles, a team of researchers led by James Gimzewski removed body fluid from suspected cancer patients.

Using atomic force microscopes - a nanotechnology gadget measured in units 10,000 times smaller than the width of a human hair - they applied minute amounts of pressure on individual cells with a sharp probe attached to a mechanical arm.

Gauging surface pressure
The term "microscope" is, in fact, a misnomer because the tool gages surface pressure rather than providing a magnified view.

The researchers discovered that malignant cells - verified as cancerous by other means - were four times as soft as normal tissue across all three types of cancer examined.

"Our work shows that mechanical analysis can distinguish cancerous cells from normal ones even when they show similar shapes," Gimzewski and his colleagues concluded.

When a normal cell becomes cancerous, its shape and its internal "skeleton" change. This transformation causes a loss of stiffness, but is not always visible.

The softness, they noted, makes it easier for malignant cells to invade and spread - or metastasise - to other parts of the body.

Further tests are needed to see whether the simultaneous existence of other diseases besides cancer in a patient might affect the mechanical properties of the cells and thus throw off the nano-scale measurements. – (Sapa-AFP)

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Cancer Centre

December 2007