Plant lectins in the prevention and control of tumour growth- future directions in cancer therapy?

Journal/Book: Exp. Opin. Invest. Drugs 4 (12), 1293-1297. 1995;

Abstract: Summarising the reports available to date: it appears that lectins havepronounced immunomodulatory capabilities and that they can elicitcytocidal actions by acting either directly on the cells themselves orindirectly via the immune system. Moreover, lectins bind to specificreceptors on the cell surface, thereby rendering them useful forselective targeting against particular tumour types. By virtue of theseproperties, lectins form a class of naturally occurring agents which canbe viewed as potential candidates for cancer chemotherapy. Consideringthe innumerable numbers of lectins available in nature, only a meagreproportion have been reviewed for their effectiveness in cancer therapy.This area needs to be explored more extensively. An examination of thehistory of cytotoxic anticancer drug development suggests that thisactivity has almost reached a plateau. Experts are of the opinion that agreater effort in biological response modification is warranted in orderto affect this plateau significantly, Reports by many investigators,including our own, point towards the possibility of utilising a sizeablenumber of plant lectins in cancer chemotherapy. However, it must beemphasised that lectins, like many other therapeutic andimmunomodulatory agents, may only have limited use as single agents.Their efficacy in combination with other cytotoxic agents merits furtherevaluation. Our experiments on a murine model have shown that somelectins may be used as adjuvants to reduce the total effective dose ofcytotoxic drugs required. This would ensure that the toxic side-effectsof chemotherapeutic agents are minimised, Future research should focuson the development of agents that can be combined effectively for use inthe management of malignant disorders. As is now appreciated, emphasisshould be placed on the development of agents with minimal toxicity butmaximal benefit. Therefore, the search for newer, promising lectins withhigher anti-neoplastic activity, broader anti-tumour spectra, lowertoxicities and enhanced immunomodulatory actions must continue.Concomitant with such an ongoing process of drug development, adequate:attention should be given to the potential use of dietary lectins andlectin-rich dietary products in the chemoprevention of cancer.

Keyword(s): Medical:cancer-therapy

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