Green tea – a remedy for cancer?

The legendary cradle of tea is China. The first notes about tea consumption are dated more than four thousand years ago. Tea is a beverage made from Camellia sinensis leaves, however, there exists several types of tea and each is collected and prepared in a specific way. Green tea is obtained from leaves that are not subjected to the fermentation process and are dried immediately after collecting. Therefore, the leaves are un-oxidized and are the less processed with the exception for white tea. Although tea originates from China, nowadays it is commonly associated with other countries like India, Japan and Great Britain.

Minimal oxidation during processing results in a great amount of chemical substances that are associated with beneficial effect on human health. These substances are bioactive natural chemicals – polyphenols which act as antioxidants with simultaneous anti-inflammatory and anti-carcinogenic effect. Majority of bio-active components are epicatechin, epicatechin-3-gallate, epigallocatechin as well as the most intensively studied polyphenolic compound and the most effective ingredient in elimination of free radicals – epigallocatechin-3-gallate (EGCG).

Since several years scientist have been involved in studies on the lactate dehydrogenase (LDH) protein which is an enzyme involved in metabolism of cancer cells. This enzyme is a key factor for maintaining proper level of nicotinamide adenine dinucleotide (NAD⁺) needed for cancer cells glycolysis. LDH is a complex molecule consisting of two subunits (LDH-A and LDH-B) each encoded by specific genes. The ratio of LDH-A and LDH-B determines the direction of glycolysis either for reduction of pyruvate to lactate in order to recover NAD⁺ from NADH (more LDH-A) or the reverse reaction in the presence of higher amount of LDH-B. Moreover, the A form of lactate dehydrogenase participates in conversion of glucose to lactate during anaerobic respiration with sufficient oxygenated conditions (Wartburg effect). This enables tumor cells to convert stored glucose into lactate and to promote cell growth and proliferation instead of using glucose for energy production. In addition, decrease in activity of LDH-A has been associated with the inhibition of tumor cells development. Hence, the knockdown of LDH-A seems to be a promising step in prevention from carcinogenic cells replication during treatment of cancer.

Currently researches have been investigated the action of oxamate – an enzyme inhibitor that contributes to decrease in LDH-A activity and thus causing the disruption of cancer cells metabolic balance and function. A similar effect was observed for studies involving epigallocatechin-3-gallate (EGCG) – the active ingredient of green tea and green tea extracts. Using various techniques for metabolic pathway assay, scientists have compared the action of oxamate and biologically active green tea component against human pancreatic adenocarcinoma cells and how they down-regulate LDHA in HPAF-II pancreatic cancer cells. It was concluded that both compounds, oxamate and EGCG, have an impact on tumor cells metabolic function disruption and, therefore, might diminish the risk of cancer. According to Dr. Lee, this study presents an entirely new approach for cancer cells, spreading the light on understanding the disruption of carcinogenic cells and thus taking up effort to prevent cancer.

MD Wai-Nang Lee is leading researcher and author of a study about green tea components and carcinogenic cells at Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed).

Literature:

http://www.sciencedaily.com/releases/2014/05/140530133214.htm

http://www.ncbi.nlm.nih.gov/pubmed/24944597

http://www.ncbi.nlm.nih.gov/pubmed/24915354

http://www.medicalnewstoday.com/articles/269538.php

http://link.springer.com/article/10.1007%2Fs11306-014-0672-8

by Agnieszka Tyfa