AsianScientist (Feb. 26, 2016) – Researchers from the University of Hong Kong (HKU) have discovered that antioxidants promote the growth of liver cancer cells. Liver cancer patients are hence recommended against taking high doses of antioxidant supplements.
The findings are applicable to other cancers that share the same metabolic pathway, such as colorectal cancer and lung cancer; and may contribute to treatments that involve blocking the antioxidant-producing systems in cancer cells. Their research was published in the Proceedings of the National Academy of Science.
Hepatocellular carcinoma (HCC) or primary liver cancer is one of the leading cancers in the world, with an annual incidence of over 500,000 new patients. More than half of the new cases occur in Hong Kong and China. The incidence of primary liver cancer is particularly high in Hong Kong, with more than 1,400 new cases per year. This is because of the high prevalence of Hepatitis B in the population; 80 percent of liver cancer patients are HBV carriers.
In mouse models of liver cancer, the study showed that excessive reactive oxygen species (ROS), or free radicals, caused more oxidative stress, while excessive accumulation of oxidative stress is harmful to cancer cells and lowers the growth rate.
The research team further discovered that the pentose phosphate pathway (PPP) produces more antioxidants in cancer cells. Oxidative stress decreases as more antioxidants are produced, and this leads to growth in cancer cells.
More importantly, the research team finds that therapeutically targeting the key enzyme, transketolase, in this pathway would create metabolic vulnerabilities in cancer cells, enhancing the sensitivity of cancer cells to existing drug treatments.
Identification and characterization of the metabolic mechanisms of liver cancer is fundamental to the understanding of the pathogenesis of the disease and the design of novel therapeutic interventions for liver cancer patients. The study therefore suggests that the PPP is an attractive therapeutic target.
“In [the] long term, our study can facilitate the development of safer, effective and targeted treatment that can be used in combination with chemotherapy to completely eradicate this deadly disease and benefit liver cancer patients,” said study lead, Professor Irene Ng Oi-lin, Loke Yew Professor in Pathology at HKU.
“Liver cancer patients are advised to have a balanced diet and they should note that a high intake of antioxidant supplements may not be beneficial to health.”
The article can be found at: Xu et al. (2016) Transketolase Counteracts Oxidative Stress to Drive Cancer Development.
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Source: University of Hong Kong; Photo: Shutterstock.
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