Understanding Tumor Growth

Certain tumors tend to metastasize preferentially to particular organs. Prostate cancer is a superb example of this kind of behavior as prostate tumors most commonly metastasize to bone, especially to the vertebrae of the spinal column.

Our earliest work on this tumor was designed to ask whether there were factors in bone that could stimulate the growth of prostate cancer cells. Work done by Marcela Chackal-Roy, a graduate student in our lab, showed that bone marrow did indeed contain factors that stimulated the growth of metastatic prostate cancer cells. This work revealed that the reason why prostate cancer metastases grow so rapidly in the spine is because of these bone-derived growth factors (Chackal-Roy M, Niemeyer C, Moore M, Zetter BR. Stimulation of human prostatic carcinoma cell growth by factors present in human bone marrow. J Clin Invest 1989; 84: 43-50).

Marcela then went on to purify one of these growth factors and show that it was transferrin, an iron-binding protein that is known to stimulate the growth of certain cell types. Transferrin is particularly rich in bone marrow where it is used in transporting iron to new red blood cells. Thus, a protein particularly abundant in bone marrow has the ability to stimulate the growth of prostate cancer cells that escape the prostate and reach the spine (Chackal-Rossi M, Zetter BR. Selective stimulation of prostatic carcinoma cell proliferation by transferrin. Proc Natl Acad Sci USA 1992; 89:6197-6201).

Stimulation of prostate cancer cells by human bone marrow-derived transferrin (_) compared with stimulation by control serum albumin (o).