Hypalgesia Effect of IL-24, a Quite New Mechanism for IL-24 Application in Cancer Treatment

Tumor suppressor melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) has been extensively regarded as an anti-oncogene; however, that whether IL-24, as a member of IL-10 family, is involved in cancer pain was seldom reported before. In this study, we found that IL-24 mediated by adenovirus could significantly increase the plantar mechanical pain threshold in both operation side and contralateral side of the animal models, which were established by injecting 5x103 Walker 256 rat breast cancer ascitic tumor cells into rats' tibia bone medullary canals; IL-24 could also suppress in vitro Walker 256 cells growth by inducing cell apoptosis. Pathologically, IL-24 could protect bone trabecula and substantia corticalis ossium from being completely destructed. Enzyme-linked immunosorbent assay (ELISA) showed that IL-24 treatment could increase the -endorphin levels and decrease the IL-6 concentration in plasma of animals. Our study indicated that IL-24 has a potential treatment effect on cancers not only by inhibiting tumor proliferation, but also by the promotion of -endorphin synthesis, inhibition of IL-6 secretion to relieve cancer pain.