Wadih Arap, MD, PhD
Dr. Wadih Arap is deputy director of the University of New Mexico Cancer Center.

One way to defeat an enemy 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.

An international team of researchers led by University of New Mexico scientists recently uncovered a new, important step of the process that grows new blood vessels that could lead to a new way to combat cancer.

The UNM Cancer Center's Dr. Wadih Arap and Dr. Renata Pasqualini lead the scientific team that identified a new type of immune cell called CD13+ myeloid cells. These cells gather around tumors and release an enzyme called CD13, which spurs a natural process called angiogenesis -- the growth of new blood vessels. Their findings were recently published in the Proceedings of the National Academy of Sciences.

Arap is deputy director of the UNM Cancer Center and professor and chief of the hematology/oncology division in the department of Internal Medicine at the UNM School of Medicine. His wife, Pasqualini, is also a professor and chief of the molecular medicine division 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.

"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," Pasqualini says. “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 and a professor of biochemistry at the Universita Vita e Salute San Raffaele in Milan, Italy. “CD13+ bone marrow-derived cells residing in the marrow might contribute strongly to angiogenesis in this context.”

Co-author Dr. Richard Sidman, a Harvard Medical School researcher, 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.”