Deactivating a cancer growth promoter

September 25, 2008,

Three enzymes called phosphatases that shut down a molecule called SRC-3 (steroid receptor coactivator 3) could provide a new pathway for fighting cancer, particularly tumors of the breast and prostate, said researchers at Baylor College of Medicine in a report that appears in the current issue of the journal Molecular Cell.

"This kind of information provides a target for the production of drugs against cancer," said Dr. Bert O'Malley, chair of molecular and cellular biology at BCM. "One can already find drugs that stimulate or inhibit phosphatases in other disease processes."

O'Malley and his colleagues had already determined that SRC-3 is an oncogene or cancer-promoting gene as well as a master switch in the cell. Phosphorylation or adding a phosphate molecule activates its cancer-promoting activities. In this study, the researchers identified three phosphatases that promote removal of the phosphate and thus halt the activity of SRC-3.

Of the three identified, PDXP, PP1, and PP2A, PP1 not only stops SRC-3 activity, it also stops the degradation of the co-activator. SRC-3 then builds up in cells, but without the phosphate, it is a dead molecule that does not function and may even further inhibit tumor growth.

Providing new avenues for fighting cancer is an important outcome of basic science, said O'Malley, who is also associate director for basic research in The Dan L. Duncan Cancer Center at BCM. "In cancer right now, many drugs work the same way. They are toxic to all cells. Because the cancer cell grows faster, the drug is more toxic, but there is nothing selective about the process. In the past decade, we have realized that there has to be a better, more intellectual approach to cancer. In fact, some already exist."

For example, the drug Herceptin targets breast cancer cells that carry the protein Her2/neu. Finding drugs that stop the activation of SRC-3, found at high levels in some breast tumors, could provide another avenue of treatment that could target just the cancer cells.

One study, published by Dr. C. Kent Osborne, director of the Lester and Sue Smith Breast Center at BCM, showed that women whose tumors have both the Her2/neu protein and high levels of SRC-3 are less likely to be helped by drugs such as tamoxifen and more likely to die quickly of their disease. Finding a way to stop Her2/neu and shut down SRC-3 could make the tumor cell's growth controllable, O'Malley said.

Source: Baylor College of Medicine

Related Stories

Recommended for you

New therapeutic gel shows promise against cancerous tumors

February 21, 2018
Scientists at the UNC School of Medicine and NC State have created an injectable gel-like scaffold that can hold combination chemo-immunotherapeutic drugs and deliver them locally to tumors in a sequential manner. The results ...

Five novel genetic changes linked to pancreatic cancer risk

February 21, 2018
In what is believed to be the largest pancreatic cancer genome-wide association study to date, researchers at the Johns Hopkins Kimmel Cancer Center and the National Cancer Institute, and collaborators from over 80 other ...

Kinase inhibitor larotrectinib shows durable anti-tumor abilities

February 21, 2018
Three simultaneous safety and efficacy studies of the drug larotrectinib reported an overall response rate of 75 percent for patients ages four months to 76 years with 17 different cancer diagnoses. All patients had tumors ...

Similarities found in cancer initiation in kidney, liver, stomach, pancreas

February 21, 2018
Recent research at Washington University School of Medicine in St. Louis demonstrated that mature cells in the stomach sometimes revert back to behaving like rapidly dividing stem cells. Now, the researchers have found that ...

Research could change how doctors treat leukemia and other cancers fed by fat

February 21, 2018
Obesity and cancer risk have a mysterious relationship, with obesity increasing the risk for 13 types of cancer. For some cancers—including pediatric cancers—obesity affects survival rates, which are lower for people ...

New technique predicts gene resistance to cancer treatments

February 21, 2018
Yale School of Public Health researchers have developed a new method to predict likely resistance paths to cancer therapeutics, and a methodology to apply it to one of the most frequent cancer-causing genes.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.