Israeli scientists find a ‘light’ way to kill cancer cells

Dr Michael Firer: We’ve uniquely combined two cutting-edge technologies to direct a drug to cancer cells and to generate a light source inside the cells.Forcing cancer cells to shine could activate light-sensitive drugs that are then able to kill them …

Dr Michael Firer: We’ve uniquely combined two cutting-edge technologies to direct a drug to cancer cells and to generate a light source inside the cells.Forcing cancer cells to shine could activate light-sensitive drugs that are then able to kill them without damaging healthy tissue nearby, according to new Israeli research.

Scientists based at the College of Judea and Samaria and in association with Bar Ilan University, have for the first time combined two innovative techniques to target leukemia cells.

The first is a form of photodynamic therapy, which delivers a light-sensitive drug specifically to cancer cells. The second technique uses a compound called luminol to produce light inside individual cells, activating the drug and killing the cell.

Leukemia is cancer of blood-forming tissue such as bone marrow. Types of leukemia are grouped by the type of cell affected and by the rate of cell growth.

“Essentially what we’re working on is targeted drug delivery, a system that allows the targeting of drugs to a particular cell – a cancer cell or a disease associated cell,” said lead researcher, Dr Michael Firer of the Department of Chemical Engineering and Biotechnology at the College of Judea and Samaria. The team’s research was recently published in the British Journal of Cancer.

Firer, originally from Australia, moved to Israel in 1983 and was a researcher for many years at the Weizmann Institute of Science. After working with biotech companies, he joined the faculty of the College of Judea and Samaria in the mid-90s.

“In our case, the system is based on the identification of receptors on the surface of target cells. Once we can ID the receptors, we can then search for peptides – small molecules that are specific for that receptor. We then link that peptide to a drug or toxin and target the cell,” he told ISRAEL21c.

Photodynamic therapy exploits the properties of certain chemicals that are activated by normal visible light. In regular photodynamic therapy, laser light is shone from outside the body to activate chemotherapy drugs. But the researchers say it may be possible to use luminol to generate light inside cells, reducing side effects and enabling the therapy to be used to treat a wider range of tumors.

While PDT has been used extensively for targeting cancer cells, Firer says that his team’s research has found the solutions for two limitations to this kind of therapy.

“The two big problems with photodynamic therapy are getting the light-sensitive drug to only target cancer cells, and delivering light to the drug to activate it once it is in the right place. We’ve uniquely combined two cutting-edge technologies to direct a drug to cancer cells and to generate a light source inside the cells. This stops the drug killing healthy cells,” said Firer.

Another limitation, according to Firer, is that PDT doesn’t penetrate the body. Its current use is for skin cancer, psoriasis, which are on, or close to, the body surface.

“What is presently done is to attach a laser fiber to a catheter which enters the body through the mouth or another way, and try to reach where the cancer is and eradiate it that way. It’s an invasive process though, and not entirely successful in reaching the required area,” he said.

“What we’ve looked for is a way to chemically activate the light sensitive compounds within a cell. We borrowed from a technology which has been around a long time – chemiluminescence – a chemical reaction which produces light. We put one and one together – we’ve shown in the research that if you take a cell culture and treat it with the light sensitive compound called luminol – it produces chemiluminescence in the cell which activates the light sensitive molecules and kills the cells.”

“This means that we might be able to use photodynamic therapy to treat tumors deep inside the body that external light sources cannot reach. We’ve shown it works in the lab – if it works in real life, we’ll have an exciting new way to treat cancer.”

According to the research, this novel chemical means of PDT activation using luminal induced cytotoxicity – or the killing of cells – in 95% of cells. Since the tests were conducted, Firer said that preliminary trials on animals have shown that the process also works in the body, not just in a cell culture.

“We’re now in the pre-clinical stage using models of leukemia, but we’re not limited to that cancer,” he said. “As long as we have the activator and the compound, it can seek out a tumor wherever it is.”