The Prostate Lab www.prostatelab.com
"Focused on the Prostate since 1996"
Research from Memorial Sloan-Kettering Cancer Center in New York seems to suggest that the strategy of removing androgens form the body may increase the development of androgen-independent cancer, the variety of cancer that eventually causes death. It is cautioned that these laboratory findings do not at present have practical application. Contemporary clinical trials seem to show that early hormonal treatment for metastatic disease is beneficial.
The January 1998 issue of Nature Medicine reports (Papandreou, Usmani, Geng, et al. Neutral endopeptidase 24.11 loss in metastatic human prostate cancer contributes to androgen-independent progression; Vol 4(1):50-56) that in laboratory experiments a cell surface protein (neutral endopeptidase 24.11 or NEP) that is responsible for destroying many of the neuropeptides* that stimulate cell growth and division is down-regulated when androgens are removed from the environment. Thus, when there is less androgen around, the stimulatory neuropeptides are not destroyed by the NEP and stimulate tumor proliferation. The abstract concludes: "These data suggest that decreased NEP expression, common in androgen-independent prostate cancers, is facilitated by the elimination of androgens, and that NEP loss plays an important role in the development of androgen-independent PC by allowing PC cells to use mitogenic neuropeptides as an alternate sourse of androgen in order to stimulate cell proliferation."
Recent clinical studies have attested to the usefulness to both quality and length of life when hormonal ablation treatment is begun early in the course of metastatic disease. These new findings suggest that if this therapy is attempted too early, it might cause the development of androgen insensitive tumor cells that might cause problems later on. It is speculated that monitoring neuroendocrine substances released in the serum or identified in biopsy specimens might help to properly time the initiation of androgen ablation therapy. The fact that prostate cancer is often heterogenous, with different portions of the tumor(s) in different stages of development would make this a most challenging task.
*These neuropeptides include such chemical mediators as bombesin, neurotenin, and endothelin-1.
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