The proliferation of cancer metastases is often a major cause of tumor complications and death. Recently a team of researchers from the Institute of Experimental Cancer Research (ISREC) at the Swiss Federal Institute of Technology in Lausanne looked closely at the formation of these metastases themselves for the first time, rather than focusing only on the primary tumors from which they originate, as has been the case previously. The researchers identified a protein that plays a key role in the formation of metastases and demonstrated that blocking this protein effectively inhibits the formation of secondary tumors. The new findings open the door to new treatment options for advanced cancers. The findings are published online in Nature. It is well known that once a malignant tumor forms, it quickly spreads cancer cells widely throughout the body. These cancer cells do not always lead to secondary tumor formation, and research has shown that all cancer cells are not created equal: only a small percentage of them, called “cancer stem cells,” can initiate metastasis. To do so, they must first set up camp in a place (the microenvironment, niche) that is conducive to their formation. Researchers at the Swiss Institute for Experimental Cancer Research have confirmed that there are several conditions that are essential for cancer to spread. “Of interest, we isolated a protein called periostin from the microenvironment where metastases form,” says Joerg Huelsken, head of the tumor formation signaling project at the Swiss Federal Institute of Technology in Lausanne, “and we confirmed that in the absence of this protein, cancer stem cells not only fail to initiate metastasis, but instead cause them to disappear or remain dormant.” Periostin protein is a component of the extracellular matrix under physiological conditions and plays an important role in embryonic development. In adults, Periostin proteins are only actively expressed in specific organs such as the breast, bone, skin and intestine. The new study confirms that Periostin may play a critical role in the microenvironment necessary for cancer stem cells to initiate tumor metastasis. The results show that mice deficient in Periostin protein are able to resist metastatic tumor formation. “We have developed an antibody that binds to the Periostin protein, which disables the Periostin protein. We hope that this approach will block the formation of metastases.” Huelsken. said. The results of the experiments show that blocking the periostin protein produces only very mild side effects in mice. “But this does not necessarily mean that the same results can be obtained in humans,” the researchers said cautiously, “and we are not even sure yet if we can find antibodies that can have the same effect in humans.” Nonetheless, the new findings are very encouraging, especially since we know that malignant tumors spread much more rapidly than previously thought. Being able to block the formation of metastases appears to be an important therapeutic option for limiting the harmful effects of cancer.