Survivin has received great attention due to its expression in many human tumors and its potential as a therapeutic target in cancer. Survivin expression has been described to be cell cycle–dependent and restricted to the G2-M checkpoint, where it inhibits apoptosis in proliferating cells. In agreement with this current view, we found that survivin expression was high in immature neutrophils, which proliferate during differentiation. In contrast with immature cells, mature neutrophils contained only little or no survivin protein. Strikingly, these cells reexpressed survivin upon granulocyte/macrophage colony-stimulating factor (CSF) or granulocyte CSF stimulation in vitro and under inflammatory conditions in vivo. Moreover, survivin-deficient mature neutrophils were unable to increase their lifespan after survival factor exposure. Together, our findings demonstrate the following: (a) overexpression of survivin occurs in primary, even terminally differentiated cells and is not restricted to proliferating cells; and (b) survivin acts as an inhibitor of apoptosis protein in a cell cycle–independent manner. Therefore, survivin plays distinct and independent roles in the maintenance of the G2-M checkpoint and in apoptosis control, and its overexpression is not restricted to proliferating cells. These data provide new insights into the regulation and function of survivin and have important implications for the pathogenesis, diagnosis, and treatment of inflammatory diseases and cancer.

Small cell lung cancer cell lines were resistant to FasL and TRAIL-induced apoptosis, which could be explained by an absence of Fas and TRAIL-R1 mRNA expression and a deficiency of surface TRAIL-R2 protein. In addition, caspase-8 expression was absent, whereas FADD, FLIP and caspases-3, -7, -9 and -10 could be detected. Analysis of SCLC tumors revealed reduced levels of Fas, TRAIL-R1 and caspase-8 mRNA compared to non-small cell lung cancer (NSCLC) tumors. Methylation-specific PCR demonstrated methylation of CpG islands of the Fas, TRAIL-R1 and caspase-8 genes in SCLC cell lines and tumor samples, whereas NSCLC samples were not methylated. Cotreatment of SCLC cells with the demethylating agent 5 0 -aza-2-deoxycytidine and IFNc partially restored Fas, TRAIL-R1 and caspase-8 expression and increased sensitivity to FasL and TRAIL-induced death. These results suggest that SCLC cells are highly resistant to apoptosis mediated by death receptors and that this resistance can be reduced by a combination of demethylation and treatment with IFNc.

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The immunomodulatory drug fingolimod (FTY720, Gilenya) was approved for oral treatment of relapsing-remitting multiple sclerosis, due to its impressive efficacy and good tolerability. Pharmacologically, it acts as an unselective agonist of sphingosine 1-phosphate receptors (S1PR) and as a selective functional antagonist of the S1P subtype by induction of receptor downregulation. Since S1P is crucial for the regulation of lymphocyte trafficking, its downregulation causes redistribution of the immune cells to secondary lymphoid tissues, resulting in the depletion from the circulation and hence immunosuppression. Numerous preclinical studies have since been performed with the aim to increase the spectrum of potential indications for fingolimod with emphasis on other autoimmune disorders and diseases associated with inflammation and uncontrolled cell proliferation, including cancer. As an alternative to fingolimod, novel S1PR modulators with a more selective receptor activation profile and improved pharmacokinetic performance and tolerability have also been developed. Preclinical and clinical studies are ongoing to investigate their therapeutic potential. This review discusses the most relevant preclinical and clinical findings from S1PR-targeting and from less-well defined off-target effects reported in the literature, and reveals perspectives for using fingolimod and functionally-related derivatives and new formulations in the management of an increasing number of diseases.