It has been known for over 60 years that in general, prostate cancer cells respond to androgen deprivation (hormonal) therapy. At some point however, the prostate cells no longer respond (they become hormone-refractory) and levels of prostate-specific antigen (PSA) begin to rise. Treating this hormone-refractory prostate cancer remains a major challenge. There is now evidence that the resulting hormone-refractory solid tumors originate from undifferentiated (less-specialized) stem cell-like cells which are thought to only comprise 0.1 percent of the original prostate tumors. Metastasis also arises from these stem cell-like cells. [Stem cells are found in all multicellular organisms; they can divide and change from being less-specialized into more-specialized cell types as well as producing more stem cells.] These cancer stem cell-like cells often do not respond to chemotherapy or hormonal therapy, so a different approach that attacks these cells in advanced prostate cancer is needed.
In a recent report on Prostate.net and in the September 20th, 2011 ZeroHour Newsletter, a Swedish research team has found that a protein called STAT3 is active in the stem cell-like cells. In addition, a natural compound called galiellalactone was found to have an effect on STAT3 and inhibits prostate cancer growth. This research represents only the initial stages of the process of developing a drug that will attack the stem cell-like cells. Using the known compound galiellalactone as a model, other better drug-like substances will hopefully be identified that will inhibit STAT3 and become new therapies that attack the stem cell-like cancer cells in men who have prostate cancer and prevent growth and spread of the disease.