Curing Cancer By Differentiation

Milan, Italy -

It is believed that out of a 1000 cancer cells, less than 1, or maybe even less than that are actual "tumor stem cells", and that this population is responsible for dividing and maintaining the tumor mass. The question has been, how to target this very small population.

A recent paper (Piccirillo et al. Bone morphogenetic proteins inhibit the tumorigenic potential of human brain tumour-initiating cells. Nature. 2006 Dec 7;444(7120):761-5) appears to have the answer (at least the first step towards the answer).

Investigators treated human glioblastoma cells with bone morphogenic protein (BMP)-4 in vitro and transplanted the cells into immune deficient mice. The ability of the glioblastoma cells to cause cancer was significantly reduced. When BMP-4 was administered in vivo none of the treated mice developed tumors, whereas 100% of untreated mice succumbed to the tumors.

Mechanistically, the tumor stem cells were shown not to die, but instead to differentiate into non-proliferating neurons. This was demonstrated by decrease of CD133+ tumor stem cells, and alteration in growth kinetics.

Since several other members of the BMP family are already in the clinic, it is curious to see if clinical trials with this approach are initiated soon.