Cancerous cells need nutrition and energy to survive, like all other cells in the body do. With this in mind, a team of researchers from Colombia University came up with the idea of cutting off the cancer cells’ supply to stop or slow their spread.
The researchers focused on pancreatic cancer because it explicitly needs an amino acid called cysteine to survive. And, it just so happened that there is a compound currently under development for a rare kidney stone disease (called cystinuria) that depletes the amino acid cysteine.
Kenneth P. Olive, Ph.D., senior author of the study, said:
Since pancreatic tumors appear to depend on cysteine import for their survival, we hypothesized that it might be possible to slow tumor growth by selectively targeting this amino acid.
They tested the drug (called cysteinase) on mice and found that it successfully starves pancreatic cancer cells of cysteine, stopping the tumor growth in mice. The research has been published in the journal Science.
Olive said:
We’re very encouraged by these results. Pancreatic cancer is a uniquely lethal disease, with an average survival rate of just six months after diagnosis. We’re in desperate need of new treatments.
The reason why cysteine is so essential to pancreatic cancer cells is that it makes them apt to withstand harsh acidic conditions. One of the ways cancer harms the body is by driving the production of oxidants. Healthy cells can’t handle the situations. However, the cancer cells can because of all the vast quantities of cysteine it has imported to enable them to produce molecules that neutralize the toxic effects of the oxidants.
Olive said:
You might imagine that all the cells of your body need every amino acid equally, but we knew from prior studies that most normal cells need only very low levels of cysteine. Our whole goal in targeting this difference between normal cells and cancer cells is to develop a treatment that is toxic to cancer and gentle on the rest of the body.
The team engineered the mice in their study to be missing the gene that controls cysteine import. The mice they used also had pancreatic cancer closely resembling tumors in humans. Since the mice couldn’t import cysteine, the cancer cells also didn’t receive any of it. As a result, they saw a halt in tumor growth and a doubling of the median survival time.
In a separate experiment, the team treated non-engineered mice with cysteinase. The results were the same. Cysteinase’s original purpose is to cut off the accumulation of cysteine in people with cystinuria to stop the formation of kidney and urinary tract stones.
The team also tested cysteinase in the lab by adding it to tissue culture containing human pancreatic cancer cells. Those died as well. And, the best part about all three successful experiments is that the approach of starving the body of cysteine appears to leave healthy cells unharmed.
Next, the team is going to see if the drugs impressive results can be enhanced by combining it with other cancer treatments, like immunotherapy.
