A protein that may suppress tumor growth has been found to be lacking in invasive breast cancer tumors, according to a new study published in the journal, Nature. Researchers have found that that the Syk tyrosine kinase, a protein that promotes chemical change, is present in normal breast tissue, benign (non-cancerous) tissue, and less aggressive breast cancer tumors, but is only found in very low levels in invasive breast cancer tumors. If further research confirms these findings, researchers say that the Syk protein could potentially by used to help treat invasive breast cancer.
According to Dr. Susette C. Mueller of Georgetown University Medical School and her colleagues, the Syk protein may halt the growth of invasive breast cancer tumors. After the researchers discovered that the amount of the Syk protein was drastically reduced in invasive breast cancer tumors, they decided to introduce the Syk protein to these tumors in mice. Giving cancerous tumors the Syk protein significantly inhibited cancer growth and cancer spread.
The researchers presume that the Syk protein helps control cell division. When it is present in only very low amounts, a tumor could grow and spread more quickly. Therefore, injecting invasive tumor cells with a type of Syk protein could help slow the growth of cancer.
| Non-Invasive Breast Cancer | Invasive Breast Cancer |
| Cancer cells that are confined to the ducts and do not invade surrounding fatty and connective tissues of the breast. Ductal carcinoma in situ (DCIS) is the most common form of non-invasive breast cancer (90%). Lobular carcinoma in situ (LCIS) is less common and considered a marker for increased breast cancer risk. | Cancer cells that break through the duct and lobular wall and invade the surrounding fatty and connective tissues of the breast. Cancer can be invasive without being metastatic (spreading) to the lymph nodes or other organs. |
While the research is promising, Dr. Mueller and her colleagues say that they do not yet know why the Syk protein is not expressed in invasive breast cancer tumors. While the Syk protein is present all tumors, it could be mutated in invasive breast cancer tumors. Ironically, most tyrosine kinases are thought to promote cancer, not suppressed it as the Syk tyrosine kinase has been shown to do.
Further research and large clinical trials with humans would be needed to determine whether the Syk protein could be used to treat invasive breast cancer. However, from preliminary research, the Syk protein does seem to block excessive cancer growth and spread.
Several researchers have expressed the need for a more complete understanding of the genetic components involved in breast cancer. Understanding the genetic differences of breast cancer will help physicians make more accurate diagnoses and could lead to more specific treatments, such as the use of the Syk protein in invasive breast cancer tumors.
- The medical study, “Syk Tyrosine Kinase Suppresses Malignant Growth of Human Breast Cancer Cells,” is published in the August 17, 2000 issue of Nature. An abstract of the study is available at http://www.nature.com/nature/ (Free registration is required to view study abstracts).
- The August 16, 2000 Reuters Health report, “Potential Breast Cancer Suppressor Identified,” is available at http://dailynews.yahoo.com/h/nm/20000816/sc/health_breast_dc_2.asp
