Why Chemotherapy Drugs Sometimes Fail

Khryss | Published 2017-10-02 01:57

Ravid Straussman at the Weizmann Institute of Science in Israel and his team were studying why healthy cells somehow helps cancer cells to resist drugs. They just couldn't explain why gemcitabine was prevented from killing neighbouring cancer cells in a sample. But with this, they were able to discover something else.

They've noticed that Mycoplasma bacteria contaminated the skin cells. That minor detail, however, was first dismissed by the group. “I almost gave up on the project,” says Straussman. Little did they know that it's actually such bacteria destroying gemcitabine! “We found that the bacteria internalise then degrade the drug, deactivating it,” says Straussman.  The bacteria just has to generate a “long form” of an enzyme called cytidine deaminase.

So, they've tested 113 samples of pancreatic cancer tissue. Of which, 86 were found to be infected with different bacteria, including E. coli and salmonella, that produce such enzyme. What's more is that 11 per cent of the 2674 bacterial species could produce such! These bacterial infections can hamper chemotherapy. They can destroy some drugs, rendering them useless. But worry not, further experiments showed that antibiotics can prevent these bacteria from destroying gemcitabine.

“Using antibiotics alongside standard cancer drugs certainly deserves further investigation,” says Yi Xu of the Health Science Center at Texas A&M University. “Treatment of cancer in the future should take into consideration the bacterial characteristics of the patients.”

Straussman, however, cautions that this need more research as long-time intake of antibiotics can encourage development of antibiotic-resistant bacteria. “We believe there may be better approaches, such as developing drugs to specifically block the activity of the enzyme that destroys gemcitabine,” he says. “This would minimise the effect of the bacteria without risking generation of antibiotic-resistant bacteria.”

Now the next move is to know whether bacteria also sabotage another anticancer drug. “We don’t think our gemcitabine discovery is an isolated phenomenon,” he says.


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