Melanoma differentiation-associated gene-7/
interleukin-24 (mda-7/IL-24), a unique member of the
IL-10 gene family, displays a broad range of antitumor properties including
cancer-specific induction of apoptosis, inhibition of
tumor angiogenesis, and modulation of anti-
tumor immune responses. Here, we identify
clusterin (CLU) as a MDA-7/IL-24 interacting
protein in DU-145 cells and investigate the role of MDA-7/IL-24 in regulating CLU expression and mediating the antitumor properties of mda-7/IL-24 in
prostate cancer. Ad.mda-7 decreased expression of soluble CLU (sCLU) and increased expression of nuclear CLU (nCLU). In the initial phase of Ad.mda-7
infection sCLU expression increased and CLU interacted with MDA-7/IL-24 producing a cytoprotective effect.
Infection of stable clones of DU-145
prostate cancer cells expressing sCLU with Ad.mda-7 resulted in generation of nCLU that correlated with decreased cell viability and increased apoptosis. In the presence of mda-7/IL-24, sCLU-DU-145 cells displayed G(2)/M phase arrest followed by apoptosis. Similarly, Ad.mda-7
infection decreased cell migration by altering cytoskeleton in sCLU-DU-145 cells. Ad.mda-7-treated sCLU-DU-145 cells displayed a significant reduction in
tumor growth in mouse xenograft models and reduced angiogenesis when compared to the vector control group.
Tumor tissue lysates demonstrated enhanced nCLU generated from sCLU with increased apoptosis in the presence of MDA-7/IL-24. Our findings reveal novel aspects relative to the role of sCLU/nCLU in regulating the anticancer properties of MDA-7/IL-24 that may be exploited for developing enhanced
therapies for
prostate cancer.