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No matter how important something is, too much of anything is bad for you. Scientists have now put that principle to work to kill cancer, with a new drug that causes calcium to build up and choke the tumor to death.

Calcium ions are crucial messengers in biological cells, and play a key role in keeping the energy-producing mitochondria functioning. They travel in and out of cells through channels that open and close with precise triggers to maintain exactly the right balance. If there’s too much calcium, the cell can suffocate. Now, scientists in South Korea and China have developed a drug that can cause a “calcium storm” inside cells on demand, and shown how to use it to fight cancer.

The drug is made up of silica nanoparticles containing a dye called indocyanine green. Tumors recognize silica and transport the nanoparticles inside the target cells, and once there, the dye is activated by near-infrared light. That sets off a two-pronged attack: first it produces molecules called reactive oxygen species (ROS) that open a calcium channel in the cell’s outer membrane. At the same time, it heats up, which causes a calcium-storing organelle inside the cell to open its floodgates.
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The technique proved effective in lab experiments on human cancer cells in a dish. Mouse tests followed, which showed that the drug accumulated in the tumors. When the researchers shone near-infrared light on it, the drug went to work and left the mice tumor-free after a few days.

While there’s still plenty more work to be done before this could be trialed in humans, the team says that the basic mechanism of activating ion channels could be investigated for a range of potential therapies.

Source: Wiley Online Library