Interruption of endogenous growth regulatory networks: A novel approach to inhibition of leukaemia cell proliferation

Several studies have demonstrated that proliferation of neoplastic cells obtained from haematologic malignancies and from solid tumours may be driven by endogenous growth-stimulatory mechanisms, and that interruption of these autocrine growth-stimulatory loops may suppress neoplastic cell proliferation. For instance, researchers have noted that interleukin-1 (IL- 1) is overproduced by acute myelogenous leukaemia (AML) and by some chronic myelogenous leukaemia marrow cells, and serve as an autocrine stimulatory cytokine. This cytokine therefore became a target for therapeutic manipulation in haematologic malignancies. Similarly, laboratory studies showing that tumour necrosis factor (TNF) may serve as an autocrine growth factor in diseases such as AML, juvenile chronic myelogenous leukaemia and neuroblastoma, suggested that inhibition of TNF activity may inhibit neoplastic cell proliferation. Interestingly, some endogenously-produced polypeptides such as soluble receptors possess these activities. The possible therapeutic potentials of these naturally occurring molecules and of artificial agents with similar activities have been recently investigated. Specifically, several IL-1- and TNF- inhibitory molecules have been recently isolated. In this review we focus on these molecules and on recent studies in haematologic diseases that have suggested the possibility of this therapeutic approach.