13 March 2008

Breast Cancer Breakthrough

A protein called SATB1 appears to be critical in transforming static tumors into metastatic ones:

Terumi Kohwi-Shigematsu, a scientist in the Life Sciences Division of the Department of Energy's Lawrence Berkeley National Laboratory who, with her colleagues, discovered SATB1 and has since investigated its many functions. She says, "SATB1's role in breast cancer is a new paradigm for the way tumors progress."

...SATB1 is not expressed in all cells. SATB1 seems particularly important in cells which must change their function... as cancerous cells must do to turn into metastatic cells.

"Only the metastatic cells expressed SATB1, with the most aggressive breast cancer cells showing the highest levels of the protein."

The researchers examined over 2,000 human primary breast cancer tissue samples for which clinical follow-up studies were available. The highest levels of SATB1 were in samples from patients whose survival times had been shortest; patients whose tumor samples had no SATB1 expression generally had longer survival times.

The analysis showed that a high level of SATB1 expression by itself is an excellent indicator of poor prognosis... because SATB1 drives breast cancer cells to become invasive...

SATB1 is a DNA-binding enzyme. When such enzymes bind to a gene sequence in the DNA they change the level of expression of a gene or genes (i.e. how much protein those genes will make). In the case of breast cells, the effect of whatever proteins SATB1 regulates has the effect of "loosening" cancer cells and letting them spread to other regions of the body.

It is possible that understanding the role of SATB1 will lead to better treatment methods but for now it only provides a valuable prognostic tool.

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