SCC-S2/GG2-1/NDED (approved gene symbol TNFAIP8) is a transcription factor NF-kappaB-inducible, antiapoptotic, and oncogenic molecule. In this study, we examined the role of SCC-S2 in invasion and experimental metastasis. We demonstrate that expression of SCC-S2 cDNA in MDA-MB 435 human breast cancer cells is associated with enhanced invasion in vitro and increased frequency of pulmonary colonization of tumor cells in athymic mice. Systemic treatment of athymic mice with a cationic liposomal formulation of SCC-S2 antisense oligo led to decreased incidence of pulmonary metastasis and inhibition of SCC-S2 expression in vivo. Antisense inhibition of endogenous SCC-S2 expression correlated with decreased expression of VEGF receptor-2 in tumor cells and human lung microvascular endothelial cells and loss of endothelial cell viability. In addition, downregulation of SCC-S2 expression in tumor cells was associated with decreased expression of known metastasis-related molecules MMP-1 and MMP-9. These results demonstrate a novel role for SCC-S2 in tumor progression, involving multiple effectors, and provide a basis for SCC-S2-targeted cancer gene therapy.
TNFAIP8 is a NF-κB-inducible, oncogenic molecule. Previous “promoter array” studies have identified differential methylation and regulation of TNFAIP8 in prostate epithelial and cancer cell lines. Here we demonstrate that TNFAIP8 expression is induced by androgen in hormone-responsive LNCaP prostate cancer cells. In athymic mice bearing hormone-refractory PC-3 prostate tumor xenografts, intravenous treatment with a liposomal formulation of TNFAIP8 antisense oligonucleotide (LE-AS5) caused reduced expression of TNFAIP8 in tumor tissues, and a combination of LE-AS5 and radiation or docetaxel treatment resulted in significant inhibition of PC-3 tumor growth as compared to single agents. The immunohistochemical evaluation of TNFAIP8 expression revealed correlation of both cytoplasmic and nuclear TNFAIP8 overexpression with high grade prostatic adenocarcinomas, while nuclear overexpression was found to be an independent predictor of disease recurrence controlling for tumor grade. Increased nuclear TNFAIP8 expression was statistically significantly associated with a 2.44 fold (95 % confidence interval: 1.01–5.91) higher risk of prostate cancer recurrence. Mechanistically, TNFAIP8 seems to function as a scaffold (or adaptor) protein. In the antibody microarray analysis of proteins associated with the TNFAIP8 immune-complex, we have identified Karyopherin alpha2 as a novel binding partner of nuclear TNFAIP8 in PC-3 cells. The Ingenuity Pathway Analysis of the TNFAIP8 interacting proteins suggested that TNFAIP8 influences cancer progression pathways and networks involving integrins and matrix metalloproteinases. Taken together, present studies demonstrate that TNFAIP8 is a novel therapeutic target in prostate cancer, and indicate a potential relationship of the nuclear trafficking of TNFAIP8 with adverse outcomes in a subset of prostate cancer patients.
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