Although liver enzymes

were not significantly elevated, alanine aminotransferase was moderately reduced in FTY720-treated and the high dose OSU-2S-treated mice (Supporting Fulvestrant solubility dmso Table 2). Alkaline phosphatase was also mildly reduced in the high dose OSU-2S-treated group. Nonetheless, levels of the affected parameters were within the normal ranges for mice. In the absence of corresponding histologic lesions, the clinical significance of these changes is unclear. To confirm that these in vivo tumor-suppressive activities could also occur in the context of a relevant tumor microenvironment, in vivo efficacy was assessed in an orthotopic xenograft model. Orthotopic tumors were established by intrahepatic injection of Hep3B-luc cells and monitored by bioluminescent imaging. Mice were treated with the agents at 5 mg/kg daily or with vehicle for 42 days. Figure 8C (left) shows that orthotopic tumors in vehicle-treated mice grew during the first 21 days of treatment, after which a plateau was reached. Tumors in FTY720-treated mice showed a gradual rise in bioluminescence over the first week of treatment, but,

by 3 weeks, mean tumor burden was suppressed to the original level. OSU-2S exhibited a higher tumor-suppressive potency than FTY720 in this model, achieving 80% reduction in bioluminescence at the end of treatment. Both treatments were well tolerated as indicated by stable body weights (Fig. 8C, right). Although down-regulation of PKCδ expression has selleck compound been reported in many cancer types, including squamous cell carcinoma,24 urinary bladder carcinoma,25 and endometrial cancer,26 information regarding the expression of this proapoptotic kinase in HCC is lacking. Thus, we used a TMA to evaluate PKCδ expression in 163 human HCC and 71 non-neoplastic liver tissue samples. Our data show a lower expression level of PKCδ in HCC relative to non-neoplastic 上海皓元医药股份有限公司 liver (P = 0.001) (Fig. 8D). Considering the translational potential

of FTY720 as a therapeutic agent for HCC, it is desirable to dissociate its S1P receptor agonist activity from its antitumor effects to avoid untoward side effects associated with immunomodulatory therapies. OSU-2S represents a proof-of-concept that these two pharmacological activities could be separated via structural modifications to develop novel antitumor agents with a unique mode of action. In contrast to FTY720, OSU-2S lacks significant effects on S1P1 receptor internalization in Huh7 cells and T lymphocyte homing in immunocompetent mice. Though devoid of immunosuppressive activity, OSU-2S exhibits twofold higher in vitro antiproliferative efficacy relative to FTY720 against HCC cells. Moreover, like FTY720, this antitumor activity is mediated, in part, through the activation of PKCδ signaling.