NEWS

In Brief

Sarah L. Zielinski

Protein Found to Promote Colon Cancer Metastasis

The protein periostin promotes the growth and development of metastatic colon cancer and could be a target for controlling the disease, according to a new study.

The majority of deaths from colorectal cancer occur because of metastasis, usually to the liver. Identifying the proteins essential for metastasis, therefore, is important for developing effective treatments for metastatic colon cancer.

In the April issue of Cancer Cell, Xiao-Fan Wang, Ph.D., of Duke University Medical Center in Durham, N.C., and colleagues searched for genes that are upregulated in metastatic colon cancer tumors. Periostin was highly expressed in more than 80% of human colon cancers, with the highest expression in metastatic tumors. When the researchers added periostin to human colon cancer cells and introduced the cells into mice, these cells were more likely to metastasize to the liver than cells without periostin.

Further study of periostin indicated that it stimulates the growth and development of metastatic tumors by promoting cancer cell survival and angiogenesis, the formation of new blood vessels.

See News, Vol. 95, No. 5, p. 350, "Microarray Studies Challenge Theories of Metastasis."

Researchers Discover New Kinase Inhibitor That Targets Leukemia

Gleevec, the first of a class of drugs known as "small molecule kinase inhibitors," has proven effective against the chronic phase of chronic myelogenous leukemia (CML) but not against the advanced phase of CML or against B-cell acute lymphoblastic leukemia (B-ALL). Researchers, however, have now found a new kinase inhibitor that may be effective when Gleevec is not.

One gene, BCR-ABL1, is found in both B-ALL and CML. In both types of leukemia, problems with enzymes known as kinases, which control white blood cell growth and development, lead to uncontrolled growth. Gleevec blocks the misbehaving Bcr-Abl kinase, but even when it works, some CML patients can develop resistance to the drug.

In the May issue of Nature Genetics, Shaoguang Li, M.D., Ph.D., of the Jackson Laboratory in Bar Harbor, Maine, and colleagues reported the discovery of a kinase inhibitor known as CGP76030 that blocks three other enzymes, known as Src kinases, that are important in B-ALL. These Src kinases are induced by the Bcr-Abl kinase but are not involved in chronic CML. When B-ALL mice were treated with the drug, B-lymphoid leukemic cell proliferation was impaired and the mice lived longer.

Although the drug was not effective against an animal model of chronic CML, the researchers noted that Src kinases may be activated in patients with advance CML or who have become resistant to Gleevec. Therefore, the researchers suggested that CGP76030 might prove effective in such patients.

Insurance Blunts Racial Disparities in Colorectal Cancer Survival

A new study has found that blacks and whites have similar rates of colorectal cancer survival when they have equal insurance coverage.

Colorectal cancer is the second-leading cause of cancer-related deaths in the United States, but the 5-year survival rate is higher for whites than blacks with cancer in all stages. These differences exist even when other factors, such as age, gender, and geography, are considered. There has been some evidence, however, that these disparities may be due to unequal treatment.

In the March issue of Cancer Causes and Control, Walter E. Smalley, M.D., of Vanderbilt University, and colleagues examined medical records from 969 elderly patients—697 white patients and 272 black patients—from throughout Tennessee who had been diagnosed with colon or rectal cancer between 1984 and 1992. All of the patients were enrolled in both Medicare and Medicaid during their illness.

The study, which examined medical records through 1999, found no racial differences in survival, although there were some small differences in treatment.



             
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