 |
|
Why prostate cancer patients fail hormone deprivation therapy
January 05, 2009Johns Hopkins scientists identify receptor type that makes cancer cells resistant to therapy, more aggressive
The hormone deprivation therapy that prostate cancer patients often take gives them only a temporary fix, with tumors usually regaining their hold within a couple of years. Now, researchers at Johns Hopkins have discovered critical differences in the hormone receptors on prostate cancer cells in patients who no longer respond to this therapy. The findings, reported in the Jan. 1 issue of Cancer Research, could lead to a way to track disease progression, as well as new targets to fight prostate cancer.
Prostate cancer cells rely on androgens, male hormones that include testosterone, to survive and grow, explains Jun Luo, Ph.D., an assistant professor at Johns Hopkins' James Buchanan Brady Urological Institute. Since 1941, doctors have taken advantage of this dependency to battle prostate cancer by depriving patients of androgens, either by castration or chemical methods. For most patients, this hormone deprivation therapy causes tumors to shrink, sometimes dramatically. However, it's never a cure-tumors eventually regrow into a stronger form, becoming resistant to this and other forms of treatment.
Seeking the reason why this therapy eventually fails, Luo and his colleagues at the Johns Hopkins University School of Medicine, the University of Washington and Puget Sound VA Medical Center looked to a key player: the androgen receptors on prostate cancer cells.
Using a large database, the researchers searched for variations of the nucleic acid RNA that prostate cells use to create androgen receptors, eventually identifying seven RNA sequences different from the "normal" androgen receptor already known to scientists. When they looked for these sequences in cells isolated from 124 prostate cancer patients, they found over-production of these outlaw variants in prostate cancer cells taken from patients whose disease had become resistant to hormone deprivation therapy. One variation-known as AR-V7, was also prevalent in a select group of patients who had never taken hormone therapy, but whose cancer aggressively regrew after surgery to remove their tumors.
To see how androgen receptors made from AR-V7 differ from others, the researchers forced lab-grown prostate cancer cells to produce only the AR-V7 sequence. Unlike cells with other androgen receptors, those with only AR-V7 receptors acted as if they were continually receiving androgens-turning on at least 20 genes that rely on androgens for activation-even though no androgens were present.
The results suggest that hormone therapy might encourage prostate cancer cells to overproduce the AR-V7 receptors over time, leading them to survive and grow aggressively even without androgens, explains Luo. In some patients, he adds, AR-V7 receptors might already be prevalent even without hormone therapy, predisposing them to an already-aggressive form of prostate cancer that won't respond as well to hormone deprivation therapy.
"We may eventually be able to develop an assay to test for this androgen receptor variant, giving us a way to test which patients are good candidates for hormone deprivation therapy and providing a way to monitor disease progression in patients already on this therapy," Luo says.
Examining the differences between AR-V7 and other androgen receptor variants may also provide researchers with new ideas to develop prostate cancer-fighting pharmaceuticals, he adds.
Johns Hopkins Medical Institutions
Seeking the reason why this therapy eventually fails, Luo and his colleagues at the Johns Hopkins University School of Medicine, the University of Washington and Puget Sound VA Medical Center looked to a key player: the androgen receptors on prostate cancer cells.
Using a large database, the researchers searched for variations of the nucleic acid RNA that prostate cells use to create androgen receptors, eventually identifying seven RNA sequences different from the "normal" androgen receptor already known to scientists. When they looked for these sequences in cells isolated from 124 prostate cancer patients, they found over-production of these outlaw variants in prostate cancer cells taken from patients whose disease had become resistant to hormone deprivation therapy. One variation-known as AR-V7, was also prevalent in a select group of patients who had never taken hormone therapy, but whose cancer aggressively regrew after surgery to remove their tumors.
To see how androgen receptors made from AR-V7 differ from others, the researchers forced lab-grown prostate cancer cells to produce only the AR-V7 sequence. Unlike cells with other androgen receptors, those with only AR-V7 receptors acted as if they were continually receiving androgens-turning on at least 20 genes that rely on androgens for activation-even though no androgens were present.
The results suggest that hormone therapy might encourage prostate cancer cells to overproduce the AR-V7 receptors over time, leading them to survive and grow aggressively even without androgens, explains Luo. In some patients, he adds, AR-V7 receptors might already be prevalent even without hormone therapy, predisposing them to an already-aggressive form of prostate cancer that won't respond as well to hormone deprivation therapy.
"We may eventually be able to develop an assay to test for this androgen receptor variant, giving us a way to test which patients are good candidates for hormone deprivation therapy and providing a way to monitor disease progression in patients already on this therapy," Luo says.
Examining the differences between AR-V7 and other androgen receptor variants may also provide researchers with new ideas to develop prostate cancer-fighting pharmaceuticals, he adds.
Johns Hopkins Medical Institutions
Prostate Cancer Current Events and Prostate Cancer News RSSCarnegie Mellon researchers link health-care debate to risk of dying in US and Europe
The current health care debate in the United States is complicated. Trade-offs between heath care expenditures, lifestyle choices and life expectancy have been suggested but seldom clearly demonstrated.
New finding suggests prostate biopsy is not always necessary
Researchers at Wake Forest University School of Medicine and the University of Wisconsin-Madison have discovered that some elevated prostate-specific antigen (PSA) levels in men may be caused by a hormone normally occurring in the body, and are not necessarily a predictor of the need for a prostate biopsy.
Does prostate-specific antigen velocity help in early detection prostate cancer?
The November issue of European Urology, the official journal of the European Association of Urology, features an article focussing on prostate specific antigen (PSA) velocity and early cancer detection. It has been suggested that changes in PSA over time aid prostate cancer detection.
New Synthetic Molecules Trigger Immune Response to HIV and Prostate Cancer
Researchers at Yale University have developed synthetic molecules capable of enhancing the body's immune response to HIV and HIV-infected cells, as well as to prostate cancer cells. Their findings, published online in the Journal of the American Chemical Society, could lead to novel therapeutic approaches for these diseases.
Chemo-radiation before prostate removal may prevent cancer recurrence
Researchers in the Oregon Health & Science University Knight Cancer Institute and the Portland Veterans Affairs Medical Center have found a combination of radiation therapy and chemotherapy given before prostate removal is safe and may have the potential to reduce cancer recurrence and improve patient survival.
Blood vessels might predict prostate cancer behavior
A diagnosis of prostate cancer raises the question for patients and their physicians as to how the tumor will behave. Will it grow quickly and aggressively and require continuous treatment, or slowly, allowing therapy and its risks to be safely delayed?
Short-term hormone therapy and intermediate dose radiation increases survivial for early stage prostate cancer
Short-term hormone therapy given prior to and during intermediate dose radiation treatment for men with early stage prostate cancer increases their chance of living longer, compared to those who receive the same radiation alone.
Task force develops new radiation guidelines for brachytherapy
Radiation dose delivered to the prostate and nearby organs in every brachytherapy procedure should be carefully analyzed using post-implant CT or MRI and uniformly documented in every patient.
1 disease, not 1 demographic
The Asian continent has nearly four billion people living in 47 different countries, and each of these groups has their own unique set of health issues. But when they come to the United States, they're often lumped into one large demographic: "Asian/Pacific Islander."
Cancer survivors may not be getting the help they need to stop smoking
More than a quarter of cancer survivors who still smoke have not been advised to quit smoking by their health care providers in the last year, according to a study published by researchers at Fox Chase Cancer Center in the current issue of the Journal of General Internal Medicine.
More Prostate Cancer Current Events and Prostate Cancer News Articles
 |
Dr. Patrick Walsh's Guide to Surviving Prostate Cancer, Second Edition by Patrick C. Walsh (Author), Janet Farrar Worthington (Author) EVERY MAN NEEDS THIS BOOK! Each year, more than 200,00 American men are diagnosed with prostate cancer. The good news is that more men are being cured of this disease than ever before. Now in a revised second edition, this lifesaving guide by Dr. Patrick Walsh and ard-winning science writer Janet Farrar Worthington offers a message of hope to every man facing this illness. Prostate cancer is a different disease in every man--which means that the right treatment varies for each man. Giving you a second opinion from the world's top experts in surgery, pathology, urology, and radiation and medical oncology, this book helps you determine the best plan for you. Learn:What causes prostate cancer--your risk factors, including heredity, diet, and environmentHow some simple changes in your... |
 |
You Can Beat Prostate Cancer by Robert J. Marckini (Author) The task of choosing the right prostate cancer treatment is daunting. It is further complicated by conflicting information the patient receives from physicians and the Internet. This book is written by a prostate cancer survivor who now runs an international prostate cancer support group. It's about his journey and the important things he learned along the way. It is the book the author wishes had been available when he was diagnosed 6 years ago. It is intended to provide specific information for men who are at risk or have been recently diagnosed with prostate cancer. All major treatment options are examined and the pros and cons of each are summarized. A relatively new, non-invasive, highly effective treatment is highlighted. It is an option that cures cancer as well as any other... |
 |
How We Survived Prostate Cancer: What We Did and What We Should Have Done by Victoria Hallerman (Author), Peter S. Albert M.D. (Foreword) Finally, a much-needed voice for the spouses and partners of prostate cancer survivors--an unflinchingly honest and beautifully written memoir about one couple's struggles and transformation that serves as a guide for others dealing with the disease. Facts: Though many sources exist for men dealing with this dreaded disease, their partners are often left on their own to figure out how to deal with personality changes and sudden "male menopause," how to redefine love and intimacy, and how to deal with side effects of the treatment. Victoria Hallerman, an accomplished... |
 |
The Cleveland Clinic Guide to Prostate Cancer (Cleveland Clinic Guides) by Eric Klein (Author) Expert medical advice from one of the nation’s top-ranked hospitals for urology and cancer care
This year, more than 230,000 men will be diagnosed with prostate cancer, while 1 in 6 men will fight prostate cancer in their lives. Prostate cancer is the most common cancer in men over age 50.
In The Cleveland Clinic Guide to Prostate Cancer, Dr. Eric A. Klein, ranked one of America’s best doctors, offers men the substantive information they need to prevent, treat, and even live well with prostate cancer. This excellent resource gives readers the trusted medical guidance Dr. Klein offers his patients, including:
* The best diagnostic tests, new therapies, and medications currently being tested in clinical trials * Insight into the treatments that have been shown... |
 |
A Primer on Prostate Cancer: The Empowered Patient's Guide by Stephen Strum (Author), Donna L. Pogliano (Author) ¡§A Primer on Prostate Cancer, The Empowered Patient¡¦s Guide¡¨ is a basic resource to be used by patients and physicians when there has been a diagnosis of prostate cancer. It outlines a strategy of disease management that is designed to maximize outcomes for the patient and his loved ones. All aspects of diagnosis and testing are discussed; all currently approved treatments for prostate cancer are described. Discussion of treatment options includes information on side effects and includes questions the patient may not think to ask his doctor. Discussions of various treatments include the salvage therapies that might be employed if primary treatment fails. There is an extensive section on the theory and practice of androgen deprivation therapy in it¡¦s various forms, since... |
 |
Prostate Cancer for Dummies by Paul H. Lange (Author), Christine Adamec (Author), Christine Adamec (Author) Hearing that you have prostate cancer, or even that you may have it, is very scary. But this disease, in many cases, is curable. Even if you have advanced cancer that's spread beyond the prostate, many treatments help extend your life for years. You need good information to help you with the decisions that lie ahead, and this book provides you with this information. Prostate Cancer For Dummies can help you if You have prostate cancer (or you think that you have it), or someone close to you has it. You want information on treatments for prostate cancer as you form a treatment plan with your doctor. You are curious about alternative therapies for prostate cancer. You want to know what actions you can take over the long-term to continue to fight your... |
 |
Surviving Prostate Cancer: What You Need to Know to Make Informed Decisions (Yale University Press Health & Wellness) by E. Fuller Torrey M.D. (Author), Carlton Stoiber (Illustrator) When Dr. E. Fuller Torrey was diagnosed with prostate cancer, none of the books he could find was current enough or comprehensive enough to satisfy his need for information. This book is for the hundreds of thousands of other men who each year receive the same frightening diagnosis. It is the book Dr. Torrey wished he had when he was facing the countless questions that a man with prostate cancer, and his family and friends, all confront. Complete, up-to-date, and readable, the book explains how to come to terms with the diagnosis of prostate cancer, evaluate the severity of the disease, and assess the variety of treatment options and their complications. Many chapters provide information other books barely consider, such as a full discussion of the causes of prostate cancer and an... |
 |
Surviving Prostate Cancer Without Surgery by Bradley Hennenfent (Author) The niche bestseller "Surviving Prostate Cancer Without Surgery" begins with the shooting of a urologist and includes a World War II Battle. The book exposes the big lie about radical prostate surgery, is filled with cartoons and simple diagrams, and is written for the average layperson in easy-to-understand style. "Surviving Prostate Cancer Without Surgery" quotes Dr. Gary Onik, M.D., Cryosurgeon and Director of Surgical Imaging at Celebration Health Hospital, Celebration, Florida, who says: "I expect that within five years we will see the death of the radical prostatectomy as a treatment for prostate cancer." The author, Bradley Hennenfent, M.D., has seen five uncles suffer from prostate cancer and his book includes many uplifting stories about less harmful treatments than surgery. Dr.... |
 |
Eat to Beat Prostate Cancer Cookbook by David Ricketts (Author) Prostate cancer is now the most common nonskin cancer among men in the United States. In 2005 alone, 250,000 new cases were diagnosed, and that number is certain to rise with each passing year. No one is more aware of this than David Ricketts, experienced cookbook author and recent prostate cancer survivor. Shortly after surgery and radiation treatments, Ricketts began to research food and lifestyle changes that might inhibit the likelihood of prostate cancer as well as its progression. The result is this uniquely specific cookbook, which takes full advantage of foods thought to fight prostate cancer while eliminating those believed to contribute to the disease. Eat to Beat Prostate Cancer Cookbook features more than 200 delicious recipes for everything from snacks, sandwiches,... |
 |
100 Q&A About Prostate Cancer, 2nd Edition (100 Questions & Answers about . . .) by Pamela Ellsworth (Author) EMPOWER YOURSELF! Whether you're a newly diagnosed prostate cancer patient, a survivor, or a friend or relative of either, this book offers help. The only text to provide both the doctor's and patient's point of view, 100 Questions and Answers About Prostate Cancer gives you authoritative, practical answers to your questions about treatment options, post-treatment quality of life, sources of support, and much more. The updated Second Edition provides a comprehensive, step-by-step discussion of what you can expect in the diagnosis and treatment of prostate cancer, while patient commentary gives you a real-life understanding of what these steps might mean for your day-to-day life. This book is an invaluable resource for anyone coping with the physical and emotional turmoil of this... |
| © 2009 BrightSurf.com |