In a new study, researchers at the Tel Aviv University have found that breast tumors enhance their growth by recruiting stromal cells, originating from the bone marrow. Although the recruitment of bone marrow-derived fibroblasts decreases the chances of surviving breast cancer, targeting these cells could be an effective way to treat the disease, according to the researchers whose findings were detailed in the recent issue of Journal of Experimental Science.
Within solid tumors, apart from the cancer cells, there are other types of cells that are not cancerous but promote tumor growth and metastasis. Similarly, breast tumors comprise of numerous fibroblast cells that stimulate cancer cell proliferation and inflammation. Further, they promote formation of new blood vessels that supply nutrients and oxygen to the developing tumor. Majority of the cancer-linked fibroblasts are thought to be obtained from the surrounding breast tissue, but other seems to appear from other parts of the body.
A group of researchers, led by Neta Erez at the Tel Aviv University, Israel have made the new discoveries in mice with breast cancer. In the research, they found that notable amount of cancer-associated fibroblasts are derived from a type of bone marrow cells which are known as mesenchymal stromal cells or MSCs. The breast tumors recruit the MSCs in the bone marrow and forces them to grow into fibroblasts, the researchers said.
As reported in the journal, the bone marrow-derived fibroblasts vary from other cancer-associated fibroblasts and are absent of ‘PDGFRα’, an important signaling protein. However, these cells produce a large amount of a protein called ‘clusterin’ that are effective in promoting the formation of new blood cells. As tumors with bone marrow-derived fibroblasts are more vascularized, they grow faster when compared to tumors with breast-derived fibroblasts.
According to the research team, some fibroblasts in the human breast tumor also lack PDGFRα, suggesting that the human tumor might recruit bone marrow-derived fibroblasts. Furthermore, tumors with low levels of PDGFRα tend to be more deadly, indicating that recruiting bone marrow-derived cells is a critical step in the progress of breast cancer.
The new study demonstrates that recruitment of cells in the bone marrow is essential for facilitating growth of the tumor, most likely by improving the formation of blood vessel, Erez said. Better understanding the functions of these cancer-linked fibroblasts could help in developing novel therapeutic methods that target both the cancer cells and the bone marrow-derived cells, she added.