SERPINB1

SERPINB1, also known as maspin (Mammary Serine Protease Inhibitor), is a protein belonging to the serpin superfamily of serine protease inhibitors. Unlike many serpins that are secreted into the bloodstream to inhibit proteases, maspin is primarily intracellular and acts as a tumor suppressor.

Function:

The main function of SERPINB1 is to inhibit cell motility and invasion, particularly in epithelial cells. It is believed to exert its tumor-suppressive effects by modulating the activity of proteases involved in the breakdown of the extracellular matrix (ECM), a crucial step in cancer metastasis. While originally identified as a serine protease inhibitor, the specific target proteases of maspin in vivo remain a subject of ongoing research. Some studies suggest it may also function independently of protease inhibition.

Expression:

SERPINB1 is normally expressed in epithelial cells, including those of the mammary gland, prostate, and skin. However, its expression is often downregulated or lost in malignant tumors, particularly in breast and prostate cancer. This loss of expression is correlated with increased invasiveness and metastasis.

Clinical Significance:

The altered expression of SERPINB1 in cancer has made it a valuable diagnostic and prognostic marker. Reduced maspin expression is generally associated with a poorer prognosis in several types of cancer. Consequently, SERPINB1 is being investigated as a potential target for therapeutic interventions aimed at restoring its tumor-suppressive function. The mechanisms regulating SERPINB1 expression are also under investigation to identify potential targets for enhancing its expression in cancer cells.