Despite the great efforts made in research into cancer, in the last two decades
therapeutic progress has unfortunately been very limited. It is crucial to seek new
avenues of enquiry able to provide solutions to this scientific challenge. Currently, the
term “Magic Bullet”, coined by Paul Ehrlich, should be revisited and applied to new,
more selective and effective cancer treatments. The peptide substance P (SP) exerts an
important role in cancer progression. After the binding of SP to the tachykinin
neurokinin-1 receptor (NK-1 receptor), the peptide exerts a mitogenic action on tumour
and endothelial cells (inducing angiogenesis). It also regulates the migration of tumour
cells and exerts an antiapoptotic effect on them. However, when NK-1 receptor
antagonists bind to NK-1 receptors, these antagonists block the functions regulated by
SP. These antagonists inhibit tumour cell proliferation (tumour cells die by apoptosis),
angiogenesis, and tumour cell migration. These antagonists are broad-spectrum
antitumour drugs. It is known that the administration of NK-1 receptor antagonists in
combination with cytostatics exerts a synergic effect and decreases the side effects
induced by cytostatics to a considerable extent. Many authors have suggested that these
antagonists should be called “Intelligent Bullets”, because cancer cells overexpress the
NK-1 receptor and hence NK-1 receptor antagonists could act as specific anticancer
drugs. The aim of the present study is to update knowledge of the involvement of the
SP/NK-1 receptor system in cancer progression. We also suggest the use of NK-1
receptor antagonists as an anticancer therapy.
Keywords: Antitumour, aprepitant, cancer, metastasis, mitogenesis, neoangiogenesis,
NK-1 receptor antagonists, substance P, tachykinin NK-1 receptor.
