Presumed Roles of APRO Family Proteins in Cancer Invasiveness.

The APRO family members may be involved in the regulation of cell growth, migration, and/or invasion. Although an APRO protein could suppress the invasiveness of several cancer cells, it has been reported that overexpression of the same APRO protein could also promote the invasiveness and/or metastasis of the same cancer cells. In general, the invasiveness of cancer cells might be associated with the function of matrix metalloproteinases (MMPs) as well as with the function of certain exosomes. However, it has been shown that exosomes involving particular APRO proteins, MMPs, and/or microRNA could contribute to the regulation of invasiveness. Here, we discuss contradictory reports on invasiveness in relation to APRO family proteins on the basis of understanding the function of MMPs and/or various exosomes. A better understanding of those mechanisms could be of use to bring about innovative strategies for cancer treatment.