Discovery could lead to new way to combat cancer

One way to defeat an opponent is to cut off its supply lines. Tumors are no different. The supply lines for tumors are the blood vessels that ferry oxygen and nutrients to the cells. Restricting the blood vessels that feed tumor cells can shrink the tumor. A cross-institutional international team of scientists recently discovered a new, important step of the process that grows new blood vessels, a discovery that could lead to a new way to combat cancer.

Wadih Arap, MD, PhD, and Renata Pasqualini, PhD, now at the University of New Mexico Cancer Center, are the leaders of the team of scientists that recently discovered a new type of immune cell called "CD13+ myeloid cells." These cells gather around tumors and release an enzyme called CD13. The team's previous studies showed that CD13 spurs a natural process called angiogenesis, which grows new blood vessels, and they report identification of the cell that makes the CD13 in their new study recently published in the "Proceedings of the National Academy of Sciences."

Dr. Arap is the Deputy Director at the UNM Cancer Center and a UNM Professor and Division Chief of Hematology/Oncology, in the Department of Internal Medicine at the UNM School of Medicine. His wife, Dr. Pasqualini, is also a UNM Professor and is the Chief of the Division of Molecular Medicine in the Department of Internal Medicine. They are experts in vascular biology — the study of blood vessels — and in drug development. The discovery of CD13+ myeloid cells as part of the complex process of angiogenesis could make them a possible target in disrupting a cancer tumor's supply line.

Says Dr. Pasqualini, "the far-reaching biological principle emphasized in this study is that the several types of cells in a given normal or pathological organ are highly interactive. They receive and deliver molecular signals with their neighbors, such that each of them appears to be unable to sustain its usual functions in isolation."
"These findings could have relevance also for bone metastasis or other cancers featuring angiogenesis (such as multiple myeloma, a blood cell cancer in which there is prominent angiogenesis in the bone marrow itself)," says Angelo Corti, one of the co-authors. "CD13+ bone marrow-derived cells residing in the marrow might contribute strongly to angiogenesis in this context."

Co-author Richard Sidman adds, "Tumor cells depend for their nutrition and growth on blood that reaches them through vessels composed of several types of cells, but also, as is less commonly recognized, on interactions of cancer and blood vessel cells with special types of non-tumor cells that are formed in the bone marrow. These cells migrate through the blood to populate the cancer tissue, where their direct interplay promotes the cancer cells to grow and even to metastasize. We identify in this paper a previously unknown subclass of these bone marrow-derived cells that represent new plausible targets for anti-cancer therapy."

SOURCE UNM Cancer Center