Navigation Links
Why chemotherapy fails
Date:5/29/2012

The fight against cancer is not won in a single battle: Long after a cancer has been beaten into remission, it can return. The reason for this is under debate, and much is unclear. New research led by Weizmann Institute scientists shows that, at least for one type of blood cancer, the source of cancer recurrence is in a set of cells that do not proliferate as quickly as regular cancer cells, and thus able to survive chemotherapy. The findings, which appeared today in the journal Blood, have some important implications for the future of the war on cancer.

Cancer involves a breakdown in the mechanism that regulates the pace of cell division. When this happens, cells divide rapidly, leading to unchecked growth that overruns the body. The most common chemotherapy drugs are those which specifically attack cells that are undergoing rapid division, and these, indeed, often destroy all the cancer and cure the patient.

But there are also quite a few leukemia patients who go through chemotherapy only to have the cancer return. Why does this happen? Several explanations have been proposed. One is that the chemotherapy does not kill every last cancer cell, leaving a few to continue dividing out of control until the disease returns in full force. A second explanation proposes that chemotherapy does get all the regular cancer cells, but there is another type of cancer cell that hides in the body. As opposed to the rapidly dividing majority of cancer cells, these undergo slow division, enabling them to evade the chemotherapy drugs. These insidious cells can give rise to new rapidly-dividing cancer cells, which is why they are known as "cancer stem cells."

Which explanation is correct? The debate is an important one because, if the first explanation holds true, improving upon the existing treatments might help, while the second implies that a completely different approach to treatment will be needed to root out the slowly dividing cancer stem cells.

To attempt to resolve that debate, the team of Prof. Ehud Shapiro of the Weizmann Institute's Biological Chemistry, and Applied Mathematics and Computer Sciences Departments, worked with scientists and physicians from Rambam Medical Center and the Technion, both in Haifa. They used a method of reconstructing cell lineage trees that has been developed over the past few years in Shapiro's lab. This method is based on the fact that the genetic material in different body cells accumulates unique mutations during cell division, and these mutations are passed on to daughter cells during cell division. By comparing mutations, one can map out cells' detailed family trees, and thus determine how far back they share a common ancestor. The end product of this analysis is a tree that reconstructs the genealogy of the cells from their earliest forebears at the base of the tree to the youngest cells at the tips of the branches.

To reconstruct the cancer cell lineage tree, the team used two sets of blood samples: the first taken from leukemia patients right after the disease was diagnosed, and the second from those patients who had undergone chemotherapy and in whom the cancer had returned. The researchers could then trace the relationships of the recurring cancer cells back to see if they descended from the original cancer cells. The lineage tree showed that, at least in some of the patients, the source of the renewed cancer was not in the rapidly proliferating cancer cells, but rather in cells that were close to the root of the tree. These cells had only divided a few times. In other words, the cancer arose from cells that divide very slowly, making them resistant to the attacks of chemotherapy drugs.

Shapiro: "We know that in many cases, chemotherapy alone is not able to cure leukemia. Our results suggest that to completely eliminate it, we must look for a treatment that will not only eliminate the rapidly dividing cells, but also target the cancer stem cells that are resistant to conventional treatment."


'/>"/>

Contact: Yivsam Azgad
news@weizmann.ac.il
972-893-43856
Weizmann Institute of Science
Source:Eurekalert

Related medicine news :

1. Breast MRI helps predict chemotherapys effectiveness
2. Accelerated chemotherapy given before surgery benefits patients with muscle-invasive bladder cancer
3. Chemotherapys effect on overall survival seems to increase based on tumor size
4. Genetic predictor of breast cancer response to chemotherapy
5. Adding drug to standard chemotherapy provides no survival benefit for older lung cancer patients
6. Chemotherapy proves life-saving for some leukemia patients who fail induction therapy
7. Progress toward new chemotherapy agents
8. New genomic test spares patients chemotherapy with no adverse effect on survival
9. How chemotherapy becomes more effective
10. First study on long-term cognitive effects of breast cancer chemotherapy finds subtle impairment among women who received CMF regimen
11. Aurora-A hinders tumor-suppressor to allow chemotherapy resistance
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/21/2017)... ... April 21, 2017 , ... During April 21-23, Super-Sod will join ... This festival offers entertainment for everyone — from the avid gardener to the landscape ... very high quality event held in a grand venue, and we are certainly looking ...
(Date:4/21/2017)... ... April 21, 2017 , ... A new medical study ... replacement patients; post-operative recovery just might be even better than they imagined. Researchers ... osteoarthritis following surgery: 262 patients under 65 and 103 patients over 75. The ...
(Date:4/21/2017)... ... April 21, 2017 , ... National pest management association survey conducted in 2010 ... bug infestations over the 5-year period. In 2015 10% or US$750 million per annum ... bug infested properties. , The health and economic consequences of bed bug ...
(Date:4/21/2017)... ... April 21, 2017 , ... In a recently released ... a summer camp for kids in Dana Point, parents are challenged to find ways ... writers caution parents to find age appropriate activities that both reinforce their child’s learning ...
(Date:4/20/2017)... Carolina (PRWEB) , ... April 20, 2017 , ... ... of the fourth book in its growing library. The Greener The Grass, ... Quarterback and alumnus of Walnut Grove High School, shares a deeply personal, hard-earned ...
Breaking Medicine News(10 mins):
(Date:4/19/2017)... NEW YORK , April 19, 2017 The ... anticipated to showcase a healthy CAGR during the forecast period ... product type in the global digital mobile X-Ray devices market, ... 2,000 Mn in 2017, expanding at a CAGR of 7% ... create absolute $ opportunity of more than US$ 100 Mn ...
(Date:4/19/2017)... , April 19, 2017 Global Prostate ... report on the prostate cancer therapeutics market analyzes ... market. Increasing prevalence of prostate cancer, launch of ... the development of new drugs & therapeutic biological ... drug due to lesser side effects are some ...
(Date:4/19/2017)... 19, 2017  Sorrento Therapeutics, Inc. (NASDAQ: ... company developing new treatments for cancer and other ... its previously announced underwritten public offering of 23,625,084 ... offering price of $2.00 per share, before deducting ... payable by Sorrento.  The net proceeds to Sorrento ...
Breaking Medicine Technology: