Iridium - the world's second-densest metal - can kill cancer cells by filling them with a lethal version of oxygen, leaving healthy tissue intact. First discovered in 1803, the metal gets its name from the Latin rainbow. The heavy, brittle and yellow metal comes from the same family as platinum and is the most corrosion resistant metal in the world.
Iridium is rare on Earth, but abundant in meteoroites. A large amount of iridium, 66 million years old, was found in the earth's crust, leading to the theory that it appeared on the planet along with an asteroid that led to the extinction of the dinosaurs.
Scientists have created a compound of iridium and organic material that they target directly at cancer cells. The compound transfers energy to cells, converting oxygen inside them into singlet oxygen, which is poisonous and kills the cell, leaving healthy tissue unharmed.
“This project is a leap forward in understanding how these new iridium-based cancer compounds attack cancer cells, and presents different mechanisms of action to circumvent resistance and fight cancer from a different angle,” said study co-author Cookson Chiu, PhD student in the Department of Chemistry. at the University of Warwick.
The laser illuminating the skin on the cancerous area starts the process - it reaches the light-active coating on the junction and activates the metal, which begins to fill the cancer cells with singlet oxygen.
Photochemotherapy - the use of laser light to treat cancer - is rapidly developing as a viable, effective, and non-invasive treatment. Patients are becoming more and more resistant to traditional therapies, so it is very important to establish new paths like this to combat the disease.
Scientists found that after being attacked by red laser light (which can penetrate deep into the skin) on a simulated lung tumor that was grown in a laboratory, the activated organic-iridium component penetrated all layers of the tumor, killing it. This demonstrated how effective and far-reaching the treatment was.
Scientists have also proven that this method is safe for healthy cells by treating non-cancerous tissue and finding that it remains intact.
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“Our innovative approach to fighting cancer, which includes targeting important cellular proteins, could lead to new drugs with new mechanisms of action. This is urgently needed,”says Pinyu Zhang, a chemistry fellow at the University of Warwick.
The scientists used advanced mass spectrometry techniques to get an unprecedented view of individual proteins inside cancer cells - and this allowed them to pinpoint which proteins were attacked by the organic-iridium compound.
After analyzing large amounts of data - thousands of proteins from simulated cancer cells - they concluded that the iridium compound damaged key cancer molecules in proteins.
“The precious metal platinum is already used in over 50% of cancer chemotherapy treatments. The potential of other precious metals, such as iridium, is being explored to create new targeted drugs that attack cancer cells differently and with minimal side effects,”said Peter Sadler, whose laboratory is in the Department of Chemistry at the University of Warwick. "It's time to find a medical use for iridium, which was brought to us with an asteroid 66 million years ago."
Ilya Khel