AsianScientist (Oct. 23, 2017) – Scientists from Singapore and Taiwan have revealed a decisive link between a compound found in some traditional Chinese remedies and liver cancers. Their findings, published in Science Translational Medicine, also showed that exposure to the compound—called aristolochic acid (AA)—is widespread throughout Asia.
The team, led by Professor Steven Rozen from Duke-NUS Medical School (Duke-NUS), Professor Teh Bin Tean from the National Cancer Centre Singapore (NCCS), Professor Alex Chang from Johns Hopkins Medicine Singapore and Professor Hsieh Sen-Yung from Chang Gung Memorial Hospital in Taiwan, first sequenced the DNA of 98 liver cancers from Taiwan. Using mutational signature analysis, they found high numbers of AA-related mutations in over three-quarters of these cancers.
“Although we knew that there was exposure to AA in Taiwan, we were very surprised to find such a high proportion of liver cancer sufferers had exposure to AA,” said Hsieh.
The team then looked at publicly available data on mutations from 1,400 liver cancers from around the world. While AA is found in plants used in traditional medicine worldwide, the team found high prevalence of exposure in other parts of East and Southeast Asia.
“This also was an unexpected finding. We did not suspect that exposure to AA was so prevalent in so many different areas,” said Rozen.
“This is a follow up study for our 2013 paper, when our team made a breakthrough in understanding the cancer-promoting action of AA in urinary tract cancer. Our new study establishes that AA is also implicated in liver cancer,” Teh added.
AA is a natural compound found in Aristolochia and Asarum plants. These plants are commonly used in traditional herbal remedies for many purposes including weight loss and slimming. AA has been officially banned in Europe since 2001 and in Singapore since 2004. Some herbs that contain AA have been banned in Taiwan since 2003, and in China, the use of some, but not all, AA-containing herbs in traditional medicine is restricted.
However, the effects of such bans may take years to materialize; so it could be years before rates of AA-associated cancers fall. In addition, herbs containing AA are easily available online. To complicate matters, herbs are often bundled and sold as formulations rather than individually, and some formulations might use herbs containing AA. Furthermore, herbs containing AA are sometimes improperly labelled, making it difficult for suppliers and consumers to be certain of the constituents of multi-herb formulations.
Plants that may contain AA include Asarum plants (细辛, xì xīn), and powered xì xīn products manufactured in Taiwan and China were recalled in Singapore in 2014 because they contained AA. Other herbs that are likely to contain AA are: 马兜铃 (mǎ dōu líng), 青木香 (qīng mù xiāng). 天仙藤 (tiān xiān téng), 广防己 (guǎng fángjǐ), 关木通 (guān mù tōng), 寻骨风 (xún gǔ fēng), 朱砂莲 (zhū shā lián, also written as 朱沙莲).
As AA-containing plants and remedies are still widely available, Professor Alex Chang, noted that “public education and awareness are very important for avoiding exposure.”
The article can be found at: Ng et al. (2017) Aristolochic Acids and Their Derivatives are Widely Implicated in Liver Cancers in Taiwan and Throughout Asia.
Source: Duke-NUS Medical School; Photo: Shutterstock.
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