Bone marrow derived cells aid in tumor metastasis

Bone marrow derived cells are cells that originate from the bone marrow.  Cancer cells can release chemical signals that, upon reception by bone marrow derived cells, may recruit these cells as pro-tumor factors that help tumor growth and metastasis.  A crucial step to tumor metastasis is angiogenesis.  Once a tumor gains access to the blood stream, it can shed cells into circulation and they can implant in other places in the body and start new tumors.  One example cited by McAllister and Weinberg is that in mouse models of melanoma, lymphoma, lung carcinoma, and mammary carcinoma, the secretion by tumors of the inflammatory cytokine granulocyte-colony stimulating factor (G-CSF) recruits pro-tumor cells from the bone marrow into the blood stream.  It was also found that these bone marrow cells had distinct sets of genes that promote angiogenesis.  Another study cited by McAllister and Weinberg showed that the secretion of osteopontin by tumor cells induced pro-tumorigenic function in bone marrow cells by recruiting them to the tumor microenvironment.  The secretion of growth factors such as vascular endothelial growth factor-A by tumor cells also recruits bone marrow derived cells to the tumor microenvironment and elicits pro-tumorigenic function that aids in angiogenesis.