Herbal remedies that cause cancer | The Scientist Magazine®

Aristolochic acid has been banned in most countries since 2003, but Thomas Rosenquist of Stony Brook University in New York says that “many Asian countries, such as India, still use aristolochic acid as part of traditional herbal medicines. It’s banned in countries like China, but it’s still readily available.”

The reason for the continued use of the plant is[practitioners] “They may take a while to accept that they’re actually harming the people they’re trying to help,” Rosenquist says, “and there may be a 20- to 30-year lag between exposure to a carcinogen and recovery.” [developing cancer]So it might be difficult to connect.

What’s more, many people may simply not know about the risks, said Steve Rosen, a professor at Duke University’s National University of Singapore Graduate School of Medicine. “I’m really hoping this paper gets out in the public eye, because I think it’s important that people really understand the risks.”

Rosenquist, Rosen, and their team conducted two separate studies to analyze genome-wide mutations in UTUC patients with known exposure to aristolochic acid. In both reports, they found that abnormal mutations called A-to-T translocations, previously identified in tissues exposed to aristolochic acid, were enriched throughout the genome of cancer cells. And the number of mutations was generally unusually high, far higher than those seen in lung cancers caused by smoking or melanomas caused by UV exposure.

“The number of mutations that we identified per megabase of DNA was quite surprising,” said Elaine Mardis, director of technology development at the Genome Institute at Washington University in St. Louis, who was not involved in the study. “Until now, we thought that melanoma was among the world leaders in terms of the number or rate of mutations, but now it appears to be well above that.”

Genome-wide analysis also revealed that mutations tended to occur at specific sequence motifs (CAG or TAG) and on the non-transcribed strand of coding DNA, indicating that some mutations were erased as a result of transcription-coupled repair. These patterns, together with the extremely high mutation frequency and prevalence of A to T translocations, were consistent with the genomic signature of exposure to aristolochic acid.

Finding the signature in a patient’s DNA probably wouldn’t change treatment, Rosenquist says. But screening for the signature in individuals thought to have been exposed to aristolochic acid might allow for earlier detection of UTUC. “We’re trying to develop a screen that detects DNA carrying these mutations in plasma and urine, and see if it’s sensitive enough to detect these cancers before other routine methods.” [would],” He said.

In addition to the known risk of developing UTUC, Rosen’s team found that the genomes of certain liver cancers show a clear signature of exposure to aristolochic acid, meaning more organs may be at risk from exposure to the carcinogen than originally thought.

Sequencing of other cancer genomes will reveal whether this is indeed the case. But for now, perhaps the most important message from these two studies is that consuming these plants is indeed dangerous. “As is often the case in cancer research, the greatest success is in prevention,” Rosen says.

M.L. Hoang et al., “Mutational signature of aristolochic acid exposure revealed by whole-exome sequencing.” Science Translational Medicine5:197ra102, 2013.

SL Poon et al., “Genome-wide mutation signature of aristolochic acid and its application as a screening tool.” Science Translational Medicine5:197ra101, 2013.