Scientists turn cancer cells into weapons against tumours

By Sola Ogundipe What if the chemical produced in abundance by cancer cells could be turned against the cancers? What if, instead of flooding the entire body with powerful drugs in an attempt to destroy a tumour, scientists could persuade cancer cells to manufacture destructive chemicals from within? That possibility is at the centre of an intriguing scientific breakthrough in Japan, where researchers have developed an experimental technique that exploits carbon monoxide produced by cancer cells to generate cancer-killing compounds inside them.

The approach turns an unusual feature of cancer biology into a potential therapeutic advantage. Rather than administering an already manufactured toxic drug that circulates through the body and can damage healthy tissues, the researchers have devised a chemical system that produces an anticancer compound inside targeted cancer cells. In laboratory experiments, the technique successfully generated toxic compounds in several cancer cell lines while leaving a noncancerous cell line without detectable production of the same compound.

Although still at an early experimental stage, the findings could open a new direction in cancer treatment, particularly in the long-standing search for ways to destroy malignant cells while sparing healthy tissues from the collateral damage associated with conventional chemotherapy. The research, led by Katsunori Tanaka at the RIKEN Pioneering Research Institute (PRI), Japan, was published in Nature Communications.

Cancer treatment has long been complicated by a fundamental problem: drugs powerful enough to destroy malignant cells can also injure normal cells. Chemotherapy, for instance, often affects healthy tissues because many anticancer medicines cannot distinguish perfectly between cancerous and noncancerous cells. The resulting damage can produce debilitating side effects, including nausea, fatigue, hair loss and suppression of the immune system.

Scientists have consequently been exploring more selective ways of delivering or generating anticancer agents at the precise location where they are needed. Tanaka and colleagues focused on carbon monoxide, a gas commonly recognised for its toxicity but also naturally produced in small quantities in the human body. Their strategy was to deliver a metal-based catalyst into cells and use the available carbon monoxide as the chemical fuel for a reaction that manufactures an anticancer substance.

In principle, the reaction would be activated predominantly in cancer cells, where sufficient carbon monoxide is available, rather than in healthy tissues. The research represents part of a developing scientific field known as therapeutic in vivo synthetic chemistry, which seeks to use chemical reactions inside living organisms to manufacture therapeutic substances where they are needed.