Apoptosis at the interface of immunosuppressive and anticancer activities:The examples of two classes of chemical inducers, oxysterols and alkylating agents
Pl. Bischoff et al., Apoptosis at the interface of immunosuppressive and anticancer activities:The examples of two classes of chemical inducers, oxysterols and alkylating agents, CURR MED CH, 7(7), 2000, pp. 693-713
Recent progresses in the understanding of molecular and biochemical pathway
s involved in apoptotic cell death offer novel perspectives for therapeutic
interventions, in particular in immunosuppressive and anti-cancer therapie
s. In this review, we examine some chemical, biological, and mechanistic as
pects of two classes of apoptosis chemical inducers: oxysterols and alkylat
ing agents. Oxysterols represent a vast family of oxygenated derivatives of
sterols. Found in both animal and vegetal kingdoms, they can be considered
as ultimate products of an oxidative stress, and are chemically inert. Som
e of them (7 beta-hydroxycholesterol, 25-hydroxycholesterol and 7,25-dihydr
oxycholesterol) are cytotoxic at micromolar concentrations towards normal a
nd tumor cells in culture, particularly lymphocytes, and reduce the growth
of murine transplanted tumors. Thus, possible applications of oxysterols in
medicine as immunosuppressants or as anticancer agents may be considered.
Alkylating agents, on the other hand, have been widely used in cancer chemo
therapy for decades. There toxicity results from their high chemical reacti
vity, causing lesions to macromolecules through covalent linkage. Some repr
esentative members of this class, mainly bifunctional derivatives which pos
sess dichloroethyl groups, such as Chlormethine, Cyclophosphamide and Chlor
abucil, express a pronounced cytotoxicity against lymphoid cells, and have
therefore potent immunosuppressive properties. Because they triggers apopto
sis via both common and distinct mechanisms, oxysterols and alkylating agen
ts provide unique tools for exploring the initiation of this phenomenon in
lymphoid cells, and may help design novel pharmacological approaches based
on apoptotic modulation of these cells.