We have already shown that
IL-10 plays an important role in immunosuppression and metastatic dissemination in the rat
B-cell lymphoma L-
TACB model. It was suggested that the up-regulation of
IL-10 production and
IL-10 receptor (IL-10R) expression would be part of the transition from primary
tumor to metastatic phenotype and that
IL-10, besides its immunosuppressive activity, may act as a
growth factor for metastatic L-
TACB cells. The treatment of L-
TACB-bearing rats with a single low-dose
cyclophosphamide decreased
IL-10 production, reverted immunosuppression and induced the immunologic rejection of
tumor metastasis without any effect on primary
tumor growth. Our current aim was to investigate the effects of
cyclophosphamide on the expression of
IL-10 and IL-10R on primary and metastatic L-
TACB cells. Considering that
cyclophosphamide is a
prodrug, we used
mafosfamide, a compound that yields in vitro the same active metabolites as
cyclophosphamide does in vivo.
Mafosfamide induced down-regulation of
IL-10 production and IL-10R expression on metastatic cells and, concomitantly, inhibited metastatic cell proliferation. We suggest that
mafosfamide would inhibit the regulatory loop mediated by the IL-10/IL-10R system and, as a consequence, metastatic cell proliferation. These results may have a considerable impact on the design of new
therapies for metastatic
lymphomas.