Green tea finds use in cancer therapy

SCIENTISTS from the Institute of Bioengineering and Nanotechnology (IBN) of A*STAR in Singapore, said new green tea-based nanocarriers are more effective in killing liver cancer cells compared to current drug delivery systems.

Existing carriers that transport drugs to tumor cells have two limitations. One is that they carry some 10% of their weight in drugs. Therefore, to deliver a specific quantity of drugs, more carriers are consumed. Patients would require more injections or a larger dosage per treatment for effective treatment. Another shortcoming of carrier systems is dilution or destabilization by plasma proteins in the bloodstream as they travel to the target tumor site. When this happens, the drug can leak before the carriers reach the target, harming healthy cells along the way.

The research team at IBN that developed the green tea nanocarriers. Clockwise from right: Dr Kun Liang, Dr Motoichi Kurisawa, Dr Joo Eun Chung, Dr Shu Jun Gao and Dr Nunnarpas Yongvongsoontorn (Photo courtesy: IBN A*STAR)

Green tea antioxidant and Herceptin tandem

IBN Team Leader and Principal Research Scientist, Dr Motoichi Kurisawa, and his group found that green tea-based carriers achieve both higher delivery of drugs to tumor sites.  In 2014, they created self-assembling nanocarriers from epigallocatechin-3-O-gallate (EGCG), an antioxidant found in green tea, and Herceptin, a breast cancer drug. The nanocarriers could load and deliver more drugs to the cancer cells and killed them more effectively than other formulations of the drug (Nature Nanotechnology, 2014).

Green tea contains epigallocatechin-3-O-gallate (EGCG), an antioxidant which the IBN team used in their drug nanocarriers (Photo: Creative Commons Zero)

The team applied the same approach to make new nanocarriers from EGCG and Doxorubicin, which can carry up to 88% of their weight in drugs. Doxorubicin is used to treat a variety of different cancers, such as that of the breast, bladder and liver, as well as leukemia. IBN’s green tea-Doxorubicin nanocarriers were tested in a liver cancer mouse model and displayed superior tumor-killing performance and stability with minimal unwanted toxicity, when compared with two other clinical formulations of Doxorubicin.

“This study corroborates our earlier findings and demonstrates the versatility of our green tea-based carrier system. We are excited about the potential of using our technology as a universal vehicle for delivering other chemotherapeutics to treat different types of cancer,” said IBN Executive Director Professor Jackie Ying.

According to Dr Kurisawa, “The unprecedented amount of drug loading in our new nanocarriers allows us to kill more liver cancer cells effectively. We are hopeful that our technology would lead to fewer side effects in patients.”

The researchers are now evaluating the loading of other types of drugs in the carrier. Their findings are published in the scientific journal Advanced Materials.

References:

1.            K. Liang, J. E. Chung, S. J. Gao, N. Yongvongsoontorn and M. Kurisawa, “Highly Augmented Drug Loading and Stability of Micellar Nanocomplexes Composed of Doxorubicin and Poly(ethylene glycol)-Green Tea Catechin Conjugate for Cancer Therapy,” Advanced Materials, (2018) 1706963.

2.            J. E. Chung, S. Tan, S. J. Gao, N. Yongvongsoontorn, S. H. Kim, J. H. Lee, H. S. Choi, H. Yano, L. Zhuo, M. Kurisawa and J. Y. Ying, “Self-Assembled Micellar Nanocomplexes Comprising Green Tea Catechin Derivatives and Protein Drugs for Cancer Therapy,” Nature Nanotechnology, 9 (2014) 907-912.