Green Tea and Leukemia

[د / أحمد محمد باذيب]

Green Tea and Leukemia




SUMMARY

Thousands of anecdotal and unsubstantiated references to green tea's health benefits can be found in the popular literature. In scientific literature, epidemiologic studies have linked reduced rates of certain cancers to cultures in Asia where green tea is a popular drink.
Legend has it that the Chinese Emperor Shen Nung discovered tea around 2737 B.C.E. He was known as the Divine Healer, and that title is almost all one needs to know about why legends, right or wrong, persist. Green tea has come down through the ages, trailing behind it mythic tales of health benefits from "cheering the heart" to reducing inflammation, from improving bladder function to treating tumors.
Kit Lee, a hematology research technician at Mayo Clinic remembers drinking it on his family's farm in Perak, Malaysia. Perak is near the town of Gopeng, where tradition holds that drinking green tea after a heavy meal aids digestion. It wasn't green tea that brought Lee from Malaysia to Mayo Clinic, but green tea turned out to be a discovery turning point for him, for fellow researchers, Neil E. Kay, M.D. and Tait Shanafelt, M.D., and potentially for thousands of patients with Chronic Lymphocytic Leukemia or CLL.
CLL is a type of Leukemia in which lymphocytes in the bone marrow generate too many white blood cells that then invade the blood stream. It is a progressive cancer that strikes older adults. There are no known risk factors, and there is no known cure. The course of CLL is highly individualized and unpredictable. Some patients need immediate treatment. Others remain in remission and never need treatment. In some patients treatment is effective. In others death comes within months.
A blood test can help determine whether the type of CLL is aggressive or not, and new biomarkers continue to be identified. But physicians must still weigh many factors in deciding who to treat and when. It would be an easier decision if chemotherapy drugs were less toxic to other organs and the immune system. It would be an easier decision if the immune system was not already compromised by the disease, if the patients to be treated were younger and less vulnerable to side-effects, and if treatment options were sure to kill the cancer cells.
Dr. Shanafelt weighs the potential risks and benefits of treatment for CLL patients as part of his daily practice. A hematologist in Mayo Clinic's Cancer Center, Dr. Shanafelt is part of a practice that includes 2000 CLL patient visits a year. As a researcher, he has been devoted to understanding the molecular mechanisms of CLL and finding more effective and less toxic treatments that can be used at the earliest stages of disease progression.
Neil E. Kay, M.D. is a hematology researcher who conducts laboratory investigations. He has devoted his 30 year career to CLL— much of it spent researching mechanisms by which CLL cells proliferate and sustain themselves. His collaborators include Dr. Shanafelt, as well as immunologist Diane Jelinek, Ph.D., Curtis Hanson, M.D. and Gordon Dewald, Ph.D. who specialize in hematopathology, epidemiologist James Cerhan, M.D., Ph.D. and his long-term senior research associate, Nancy Bone. It was Dr. Kay who hired Kit Lee. It was green tea that brought Dr. Kay, Kit Lee, and Dr. Shanafelt together.
Having Your Cake and Eating it Too—The VEGF Autocrine Loop

Drs. Shanafelt, Lee, and Kay
Apoptosis and angiogenesis are two very different normal biologic functions that can go awry in cancer. The question Neil Kay was asking five years ago was whether the two were related in CLL. A green tea extract confirmed that they were.
Apoptosis refers to natural cell death. Without it there is a disruptive proliferation of cells. This is what happens in certain types of cancer. In CLL, cells known as CLL B cells block apoptotic signals creating bone marrow tumors that generate uncontrolled accumulation of functionless white cells in the blood.
Tumors, like every other tissue in the body need blood to survive. Angiogenesis, the growth of new blood vessels, is the process by which they do so. It is controlled by "on" and "off" switches that can either stimulate or inhibit new vessels. Under normal conditions, new vessels grow to restore blood to injured tissue. In diseases like coronary artery disease, inhibitors tip the balance toward inadequate vessel growth. In certain cancers, stimulators or cyotkines, called angiogenic growth factors mediate angiogenesis and provide tumors with an independent blood supply. In solid tumors, the new blood supply not only supports and sustains tumors but also promotes ****stasis by allowing malignant cells to travel though the blood stream to other organs.
The challenge has been to find the key players in the long list of angiogenic growth factors identified in the past ten years--to understand how they work and how to stop them. Neil Kay had been on the trail of a candidate cytokine in CLL called vascular endothelial growth factor or VEGF. Previous work had focused on the role of VEGF angiogenesis of solid tumors. Dr. Kay's group was among the first to investigate and confirm its role in blood and lymph cancers like leukemia and to show that CLL B cells spontaneously secrete VEGF. They published their findings in Leukemia in 2000 and 2002.
They suspected that VEGF plays a role not only in angiogenesis, but also in CLL B cell survival, helping to mediate resistance to apoptosis. In 2004 they found a pathway that allows VEGF to bind back onto the cell from which it was secreted. From there it activates a series of signaling proteins that advance back to the cell's nucleus and turn on genes that produce more VEGF. And the cycle repeats itself. This autocrine loop or self-promoting pathway enables CLL B cells to both resist apoptosis while enhancing the blood supply they need to flourish--that is, to have their cake and eat it too.
Encouraged by their discovery, the next step was to confirm the VEGF autocrine pathway by finding an agent that blocked it. If they did so, it might lead to designing treatments to prevent it.
Enter Green Tea

Green Tea Leaf
Hard at work in Dr. Kay's lab to find ways to disrupt VEGF signaling pathways, Kit Lee thought often of the patients he was trying to help. His interest in the effects of drug interactions and finding less toxic medications began in his youth as he monitored the health and medication of the livestock on his family's farm. It was what led him to the United States to study pharmacology and, ultimately, join Dr. Kay's research group.
Kit Lee knew, as did Dr. Kay, that a chemical in green tea had been reported to have anticarcinogenic functions, most of which remained speculative. Green tea, unlike black tea, is not subjected to high temperatures in the drying process. As a result, it contains much more abundant levels of a polyphenol called epigallocatechin 3-gallate (EGCG) than are found in black tea. EGCG had been found to inhibit experimental tumor growth in animals, and in 2002 was found to have VEGF receptor inhibiting properties.
Kit Lee proposed an experiment to explore the ability of EGCG to induce apoptosis in CLL B cells by blocking VEGF from binding back onto VEGF receptor sites its host cell. If it did so, it would add evidence to confirm the VEGF signaling pathway in CLL, and it might mean they could design it into a new CLL therapy--one with far less toxic effects than current drugs.
A Eureka Moment

The moment when Kit Lee found that ECGC was working to induce apoptosis was a moment he will long remember. He and Dr. Kay found that 80 percent of the CLL blood samples in the test tube showed improvement. Although green tea had been studied as a preventative, its properties as a therapeutic agent had not been investigated. They knew they were starting on the road to human trials. That road can be long and arduous when proposing a novel therapy, but they hoped to move their findings from bench to bedside as rapidly and efficiently as possible in early-stage CLL patients.
Dr. Shanafelt was just as eager to take their findings into clinical trials. So were patients who had heard about the initial in vitro success in the news. Four CLL patients told their physicians that they had spontaneously started taking various forms of over-the-counter green tea. As long-term Mayo Clinic patients, their medical histories were well documented. They agreed to have their progress monitored. At the end of the study, three of the four met the standard clinical trial criteria used to define a positive response, and their results were published online in a small case study in Leukemia Research in 2005.
Dr. Shanafelt, the senior author, was impressed but cautioned that while the laboratory findings may translate into clinical effects, "we do not know how many patients were taking similar products and failed to have any benefit. We also do not yet know the optimal dose that should be used, the frequency with which patients should take the medication, and what side effects will be observed with long term administration."
These questions became the focus of the clinical trial— the first one ever designed to test green tea as a therapeutic agent in the treatment of cancer.
The Clinical Trial— Translational Research in Action

Dr. Shanafelt shepherded the clinical trial proposal through the National Cancer Institute. It was funded in less than a year. Additional funding came from a patient advocacy group called CLL Topics and from CLL Global Research Foundation, both charitable organizations made up of patients with CLL and their families who support the development of new treatment strategies for CLL. Their funds are being directed toward laboratory work to determine how EGCG might be combined with other chemotherapy and antibody drugs in CLL. Their contribution is highly valued by the research team, who are grateful to the hundreds of patients over the years who have been so willing to give blood samples and participate in CLL research.
Phase I of the clinical trial began in late 2005 with Phase II to follow upon its completion. The goal is to find the right dosage, to discover if the benefits of EGCG translate from test tube to patients, and to assess risks and side-effects. The tea itself comes in capsule form in highly concentrated and controlled levels of EGCG. It comes from a tea company in Japan to the National Cancer Institute and from there to Mayo Clinic.
If successful, EGCG therapy will mean new hope of a non-toxic intervention for CLL patients. Future studies will include testing combinations of ECGC with traditional chemotherapy and antibody agents in later stage CLL patients and in other types of leukemia. Preliminary results from the first 11 patients in Phase I look promising.
Kit Lee, Dr. Kay, and Dr. Shanafelt become animated when talking about their hopes for this line of research and its potential benefits for CLL patients. It makes one think that perhaps through the mists of time, Emperor Shen Nung, the Divine Healer, is cheering them on.

[قطرات الندى]

Salam Alikom

doctor Ahmed

Thank you So much for this important imformations,,,,
and that great topic
May allah bless you and rewards you paradise
And yes,, Green tea is very good and healty
..for our bodies ,and i read alot about it
Again, thank you and hope we see your writes and topics alawys here and in all forum rooms

fi aman elah
and EId Moubarak

[silent whisper]

masalah gr8 topic Doc
thank u so much

[نور]

Assalamu Alykom wa rahmatu ALLAH
Thanks a lot Doctor Ahmed
for this importanat Topic
fi aman ALLAH

[ashraf3h4]

so many thanks dr
may Allah bless you
great information
Allah create every good to mankind
thanks again dr may allah bless you