ABSTRACT: The growth of a murine non-Hodgkin lymphoma (NHL) tumour, either as an intraperitoneal ascites tumour or as a solid subcutaneous tumour, has been shown to be greatly reduced by including phytohaemagglutinin (PHA), a lectin present in raw kidney bean (Phaseolus vulgaris) in the diet. The reduced rate of growth occurred in a dose-dependent manner. Based on the experimental observations it has been suggested that a competition occurs between the gut tissue undergoing hyperplasia and the developing tumour for nutrients (including polyamines) from a common body pool. This may be an important factor with regard to the observed initial low level of tumour growth following the feeding of a PHA-containing diet. Results showing that the level of hyperplasia of the small intestine in response to feeding the PHA diets was higher in non-injected mice compared to those which had been injected with tumour cells substantiated the concept of competition between gut and tumour for nutrients etc. required for growth. The observations suggest that lectins, which exhibit growth-promoting effects on the gut, may have interesting applications in the formulation of new approaches with respect to cancer treatment.
COMMENTARY: Polyamines are a class of molecules known to enhance the growth of many common cancers. Since they are necessary for cell growth, efforts have been launched in recent years to develop anti-cancer drugs that work via inhibiting polyamine production. One of the two basic ways polyamines are produced is via the gut (the other being production in the liver). In recent years the use of lectins as a inhibitor of polyamine production in the gut has become an area of intense research. The theory is that dietary lectins cause the intestinal cells to 'sequester' polyamines inside themselves, thereby depriving the tumor cells of polyamine stimulation.
Perhaps the most important point behind this article is that lectins are not always 'bad' and in fact may under conditions of appropriate usage be quite helpful. Perhaps the best experimental design might be to use non-blood type specific lectins which do not have the ability to agglutinate or inflame the intestinal tract of the host.
The Ask Dr. D'Adamo internet advice column ran from 1996 to 2009, at which time Dr. D'Adamo's teaching and programming responsibilities no longer allowed him to
devote time and resources to directly answering visitor questions. However we've recently reorganized this treasure-trove of material and made it again available to his readership. He occasionally posts new entries. These are marked with a NEW tag.