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Colon cancers with microsatellite instability (MSI) demonstrate a host immune response characterized by tumor infiltrating lymphocytes (TILs) that may exert effects upon tumor cell apoptosis and cell proliferation. Accordingly, we compared rates of apoptosis and cell proliferation in colon cancers with defective DNA mismatch repair and their association with phenotypic features and clinical outcome. Primary Astler-Coller stage B2 and C colon carcinomas (n = 329) were analyzed for MSI and for hMLH1 and hMSH2 protein expression. Apoptosis (TUNEL assay) and p53 expression were also analyzed by immunohistochemistry, and TILs were quantified by morphology. DNA ploidy and proliferation (PI: S phase + G(2)M) were evaluated using flow cytometry. MSI-H (n = 58) colon cancers showed increased TILs that were significantly associated with increased apoptosis, higher apoptosis to proliferation (AI/PI) ratios, reduced proliferative indices (PI) and diploid DNA content. Increased TILs (p = 0.036) and reduced PI (p = 0.042), but not AI or AI/PI, were associated with improved disease-free survival. Tumors with MSI-H (p = 0.032) or loss of hMLH1 or hMSH2 proteins (p = 0.040), or diploidy (p = 0.0015), had better adjusted overall survival rates. Interestingly, similar rates of cell turnover and overlapping survival rates were found in diploid MSS/MSI-L tumors and in MSI-H cases. In conclusion, higher apoptosis/proliferation ratios and reduced cell proliferation are phenotypic features of MSI-H tumors that are associated with increased TILs, indicating an activated immune response that may contribute to their favorable survival rates., ((c) 2006 Wiley-Liss, Inc.)

Background & Aims: Hepatocellular carcinoma (HCC) is the third most common cause of cancer death worldwide. Improved treatments for advanced HCC are urgently needed. The recently identified human sulfatase 1 enzyme (SULF1) desulfates cell surface heparan sulfate glycosaminoglycans and down-regulates cell growth signaling in HCC cells in vitro. While investigating the epigenetic regulation of SULF1, we discovered that histone H4 acetylation is up-regulated by SULF1 in HCC cells. Histone deacetylase (HDAC) inhibitors reprogram cellular gene expression through the acetylation of nucleosomal histones and promote cell growth arrest and apoptosis. Hence, they are a promising modality for cancer treatment., Methods: To explore the interaction between SULF1 expression and HDAC inhibitor action, we examined the effects of SULF1 expression on HCC cells and xenografts treated with HDAC inhibitors., Results: (1) Forced expression of SULF1 significantly delayed the growth of Huh7 and Hep3B xenografts in nude mice in vivo. (2) SULF1 increased histone H4 acetylation by modulation of cellular HDAC and histone acetyltransferase activities. (3) SULF1 enhanced the induction of apoptosis by the HDAC inhibitors apicidin and scriptaid. (4) SULF1 enhanced the inhibition of tumor growth, migration, and angiogenesis by HDAC inhibitors. We also demonstrate that knockdown of SULF1 with shRNA constructs up-regulates phosphorylation of AKT and Erk and attenuates apicidin-induced apoptosis. The interaction between SULF1 and apicidin was confirmed in vivo in Huh7 and Hep3B xenografts., Conclusions: These results show that SULF1 promotes histone H4 acetylation, potentiates the effects of HDAC inhibitors, and inhibits HCC tumorigenesis.