Botulinum toxin is a naturally occurring molecule, and historically has been implicated with intestinal poisonings. It has been developed for several clinical applications, including facial spasms, strabismus (a disease of the eye muscles), and other muscle hyperactivity. It also has become popularly known as Botox for its cosmetic uses on the face.
The toxin acts on the nervous system by blocking the release of neurotransmitters, particularly acetylcholine and norepinephrine. Gallez and his colleagues hypothesized that since Botulinum toxin impeded neurotransmitter release in the sympathetic nervous system, it could prevent neuromuscular contractions of vessels in tumors. The inhibition of this contraction could literally open the gate to improved tumor perfusion by chemotherapeutic drugs and oxygenation that enhances radiotherapy.
The scientists used two tumor models, one for fibrosarcoma and the other for mouse liver tumor. Botox was injected into the tumor once it had grown to about 6 mm. The tumors were then examined for three days, for vascular and perfusion changes as well as responses to anti-cancer therapies. In tests on oxygenation, cellular oxygen pressure was shown to significantly increase after treatment by Botox in both types of tumors. In tests on perfusion, magnetic resonance imaging results (MRI) showed significantly greater perfusion in treated mice after three days.
In addition, Botox "pre-treatment" led to significantly greater delays in tumor growth as well as stimulation of apoptosis (programmed cellular death) when compared by irradiation without Botox. The combination of Botox and the chemotherapeutic agent cy
Source:American Association for Cancer Research