Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Green tea may negate the effects of a common cancer therapy

04.02.2009
Green tea products have become regarded as a valuable health supplement, as studies have shown evidence of its benefit against a variety of diseases, including cancer.

However, a new study suggests that some components of green tea may counteract the anticancer effects of one cancer therapy, bortezomib (Velcade®), and may be contraindicated for patients taking this medicine to ensure its maximum therapeutic benefit. This study is being prepublished online today in Blood, the official journal of the American Society of Hematology.

Because of its increasing popularity and availability to the public in many formulations, green tea has been increasingly studied to understand its effect on cancer, heart disease, and other conditions. In animal studies, an antioxidant compound in green tea called the EGCG polyphenol (epigallocatechin gallate) has been shown to be a potent anticancer agent, with effects demonstrated against leukemia, as well as lung, prostate, colon, and breast cancer. Among other properties, EGCG binds to a common protein in tumors called GRP78 (which is responsible for preventing cell death) and inhibits its function, thereby assisting in the death of tumor cells.

“We know that cancer patients look to green tea extracts among other natural supplements to complement their therapeutic regimens. We wanted to better understand how the compounds in green tea interact with a cytotoxic chemical therapy and how that may affect patient outcomes,” said Axel Schönthal, PhD, of the University of Southern California Keck School of Medicine and senior study author.

In this study, researchers evaluated whether the combination of green tea and bortezomib would improve outcomes against multiple myeloma, a blood cancer, and glioblastoma, a malignant brain tumor. Bortezomib, an anticancer therapy approved to treat multiple myeloma and mantle cell lymphoma, normally fights disease by inhibiting proteasomes and inducing tumor cell death. However, in both in vitro and in vivo mouse experiments, the team was surprised to find that the EGCG compound seemed to prevent bortezomib from fighting the disease by blocking its proteasome inhibitory function – the two compounds effectively contradicted one another in the cell, leaving nearly 100 percent of the tumor cells intact.

Importantly, the team found that EGCG only reacted with proteasome inhibitors that have a boronic acid base (including bortezomib) but did not react with several non-boronic acid-based proteasome inhibitors (such as nelfinavir [Viracept®], a treatment for HIV). The researchers determined that the boronic acid in bortezomib helped to bind the EGCG directly to the therapy molecule, thereby cancelling out the effects of both the green tea and the therapy on the tumor cells.

The study findings may have several important implications in the clinical setting. The EGCG blocked bortezomib’s antitumor effects at levels that are commonly achieved with the use of available concentrated green tea supplements (as low as 2.5 μM – which can be attained with two to three 250 mg capsules of green tea extract) suggesting the impact is very real for patients supplementing their therapy. The team also believes that as the EGCG inactivates bortezomib’s function in the tumor cell, it may also prevent some of the side effects that usually accompany the therapy. As a result, patients taking green tea products to supplement their therapy may experience improved well being and feel encouraged to increase their intake while unknowingly blunting or completely negating the efficacy of their bortezomib treatment.

“Our surprising results indicate that green tea polyphenols may have the potential to negate the therapeutic efficacy of bortezomib,” said Dr. Schönthal. “The current evidence is sufficient enough to strongly urge patients undergoing bortezomib therapy to abstain from consuming green tea products, in particular the widely available, highly concentrated green tea and EGCG products that are sold in liquid or capsule form.”

The findings of the study are considered specific for patients taking bortezomib as opposed to any other common cancer therapy. The analysis of the study offered a clear understanding of the boronic acid-related mechanisms that cause the negative outcome, offering the conclusion that green tea would counteract most, if not all, compounds that work with boronic acid. However, while there are many chemicals that contain boronic acid, few are being used with patients.

“Although the study has exposed detrimental effects of green tea in specific combination with Velcade, this should not minimize the previously reported potentially beneficial effect of this herb,” said Dr. Schönthal. “Related studies with other types of cancer therapies are promising and green tea extract may actually improve the anticancer effects of other drugs.”

Patrick C. Irelan | EurekAlert!
Further information:
http://www.hematology.org

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>