Navigation Links
Study Suggests How Some Cancers Resist Treatment
Date:4/1/2010

Finding shows drug resistance can be lost, treatment can work again

THURSDAY, April 1 (HealthDay News) -- Scientists have identified a mechanism by which certain tumor cells that become resistant to cancer drugs can later lose that resistance.

The discovery may lead to new ways to combat drug resistance in cancer patients, said the authors of the new study, published online April 1 in the journal Cell.

Although the existence of these drug-resistant cells has been common knowledge, scientists "now understand a little bit better how those cells work so they can attack them," said Robert Clarke, a professor of oncology and physiology and biophysics at the Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C.

Study senior author Jeffrey Settleman, scientific director of the Massachusetts General Hospital Cancer Center and professor of medicine at Harvard Medical School, said: "One of the big problems with cancer drug therapy is acquired drug resistance. Most treatments, even ones that work, fail over time because tumors become drug-resistant. It's been largely assumed, and in some cases even demonstrated, that random gene changes confer a lot of that resistance."

But some tumors become susceptible to the cancer drugs after a "drug holiday," indicating that other mechanisms are at play.

"There's a population of cells that's resistant but the resistance is not necessarily maintained forever," Clarke noted.

"This suggests that the resistance is not genetic but could be reversible," added Settleman.

Using models of drug-resistant cells, the study authors found a subpopulation of tumor cells that managed to escape the effects of cancer drugs even when given at levels 100 times greater than those that would kill most cells.

The authors tested a number of different drugs, including gefitinib (Iressa), which is used to treat lung cancer, and lapatinib {Tykerb), used to treat breast cancer. Most of the drugs were provided for free by their manufacturers.

"We always found a small population of cells resistant to treatment and arising at significantly high frequency, [so] we thought it can't be genetic. The numbers just didn't make sense," Settleman said.

But the cells, once removed from the "drugged" environment, gave rise to a new generation of cells that were again susceptible to the drug therapies.

"Cells could randomly acquire and relinquish that drug-tolerance quality at low frequency so that any cell could potentially become drug-tolerant for a period of time, then surrender that ability," Settleman explained. This may be a way for the cells to survive as a group, with individual cells "compromising something for the good of the population," he stated.

An enzyme that changes chromatin, part of the structure of chromosomes, is necessary for a cell to develop tolerance. Although there are no drugs that can inhibit this enzyme, compounds that blocked a group of related enzymes did manage to kill off the drug-resistant cells, the researchers said.

"We discovered that there are inhibitors of certain chromatin-modifying enzymes that can actually selectively kill drug-tolerant cells," Settleman said. "That's where the therapeutic opportunity comes in. We showed that when you combine one of the chromatin-modifying enzyme inhibitors with [a drug] that treats most of the cells, you can wipe out most of the population."

The researchers are now starting a trial to combine an enzyme inhibitor with a lung cancer drug to see if they can prevent the development of resistance.

More information

Learn more about cancer drug resistance at Emory University.



SOURCES: Jeffrey Settleman, Ph.D., scientific director, Massachusetts General Hospital Cancer Center, and professor, medicine, Harvard Medical School, Boston; Robert Clarke, Ph.D., D.Sc., professor, oncology and physiology and of biophysics, Georgetown Lombardi Comprehensive Cancer Center, Washington, D.C.; April 1, 2010, Cell, online


'/>"/>
Copyright©2010 ScoutNews,LLC.
All rights reserved

Related medicine news :

1. Study shows partial lung removal favorable over full removal as treatment for lung cancer
2. New mums beat the blues and increase wellbeing with physio exercise, study reveals
3. Small soda taxes insufficient to curb consumption among children, study finds
4. Study Revives Debate on Prostate Drug
5. Misinformation about antibiotics can travel to large audience via Twitter: study
6. Minority women least likely to gain access to a doctor, study says
7. New national study examines weight training-related injuries
8. Misinformation About Antibiotics Can Travel to Large Audience Via Twitter: Study
9. Radiation after mastectomy underused, U-M study finds
10. Study shows that mutations in 1 gene cause many cancers
11. Age Management Leader Goes Beyond 2010 NANES Study Reqs, Targeting Heightened Obesity Group, Adult 40+
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/13/2017)... ... October 13, 2017 , ... PurhealthRX , a leading Health ... technology. Applying the Purzorb™process to full spectrum CBD oil will revolutionize the rapidly growing ... form that can be easily incorporated into liquid products, while reducing costs to end ...
(Date:10/13/2017)... Calif. (PRWEB) , ... October 13, 2017 , ... Many ... dementia. However, many long-term care insurance companies have a waiver for care if the ... 90-day elimination period, when the family pays for care, is often waived, so the ...
(Date:10/13/2017)... ... October 13, 2017 , ... Yisrayl Hawkins, Pastor and Overseer at The House ... most popular and least understood books in the Holy Scriptures, Revelation. The Book of ... baffled scholars for centuries. Many have tossed it off as mere rubbish, but Yisrayl ...
(Date:10/13/2017)... ... ... “America On The Brink”: the Christian history of the United States and ... of published author, William Nowers. Captain Nowers and his wife, Millie, have six ... years in the Navy. Following his career as a naval aviator and carrier ...
(Date:10/12/2017)... ... October 12, 2017 , ... The company has developed ... consumer and regulatory authorities worldwide. From Children’s to Adults 50+, every formula has ... highest standard. , These products are also: Gluten Free, Non-GMO, Vegan, Soy ...
Breaking Medicine News(10 mins):
(Date:10/11/2017)... PARK, Calif. , Oct. 11, 2017  BioPharmX ... national scientific team that developed an innovative way to ... quantity of the delivery of new drugs. ... 2017 Fall Clinical Dermatology Conference will show how researchers ... General Hospital, Harvard Medical School used a suite of ...
(Date:10/11/2017)... -- Hill-Rom Holdings, Inc. ("Hill-Rom") (NYSE: HRC), today provided an ... Puerto Rico , where the company ... Following a comprehensive onsite assessment, ... damage, temporary loss of power and minimal water damage ... operations have resumed, and the company expects to return ...
(Date:10/7/2017)...   Provista, a proven leader in the ... purchasing power, today announced a new resource area on ... is the online home for case studies, articles ... news releases, slideshows and events. ... resources at their fingertips, viewers can also watch short ...
Breaking Medicine Technology: