Curcumin, a dietary polyphenol derived from the root of the plant Curcuma longa, has shown potential as a chemopreventive (cancer-preventing) substance, with beneficial effects affecting different stages of cancer development. Curcumin has an anti-tumor effect by modulating the multiple genes involved in tumor cell proliferation, programmed cell death, invasion, and new blood vessel growth (angiogenesis). The poor absorption of orally ingested curcumin, however, has been considered a limitation of its use in cancer prevention.
Researchers at Wayne State University, Detroit, and the University of Minneapolis, have now developed an injectable, sustained-release formulation of curcumin microparticles that dramatically inhibited the growth of tumors in laboratory mice. The microparticles, consisting of microscopic spheres of curcumin in a biodegradable polymer, were injected into mice bearing human breast cancer tumors. Mice that received the curcumin microparticles had significantly less tumor growth and a reduction in markers of tumor angiogenesis, including the development of microscopic tumor capillaries and expression of a key angiogenic protein, compared with mice that received a placebo.
Notably, steady blood levels of curcumin were maintained for 4 weeks following a single injection of microparticles. The levels of curcumin were significantly higher in the lungs and brain, common sites of breast cancer metastasis, than in the blood. This would suggest that the microparticle approach might also potentially have a protective effect to keep metastases from forming in those organs.
The research group also studied repeated injections of curcumin microparticles and speculated that the steady blood concentrations of curcumin provided by the microparticles may provide a “metronomic chemotherapy”-like effect, in which regular, low-dose chemotherapy suppresses tumor growth by inhibiting angiogenesis. While requiring validation in human studies, these results suggest that new ways to deliver a dietary-derived antiangiogenic molecule as a drug. The findings were reported in the journal Cancer Research (2010;70(11):4443–52).