104 research outputs found

    Long telomeres at baseline and male sex are main determinants of telomere loss following chemotherapy exposure in lymphoma patients

    No full text
    Although chemotherapy (CHT) exposure is an established cause of telomere attrition, determinants of telomere length (TL) dynamics after chemotherapy are poorly defined. In this study, we analyzed granulocyte telomere dynamics in 34 adult lymphoma patients undergoing first-line CHT. TL was measured by southern blot at each CHT cycle and after 1 year from CHT completion. Median age was 59 yrs (range 22-77). Median number of CHT cycles was 6 (range 3-6). The majority of patients (79%, n = 27) experienced TL shortening following CHT exposure. Mean telomere loss was 673 base pairs (bp) by cycle 6. Telomere shortening was an early event as 87% of the total telomere loss (mean 586 bp) occurred by the end of cycle 3, with no significant recovery after 1 year. A significant correlation was observed between baseline TL and total or fractional telomere loss (p < 0.001), with telomere shortening by cycle 3 observed predominantly in male patients with long telomeres at pre-treatment evaluation. Stratifying the analysis by gender and age only young women (<51 years of age) did not show significant telomere shortening following chemotherapy exposure. These findings indicate that gender and baseline TL are major determinants of TL dynamics following chemotherapy exposure in lymphoma patients

    Tumor angiogenesis and progression are enhanced by Sema4D produced by tumor-associated macrophages

    No full text
    Increased evidence suggests that cancer-associated infiammation supports tumor growth and progression. We have previously shown that semaphorin 4D (Sema4D), a ligand produced by different cell types, is a proangiogenic molecule that acts by binding to its receptor, plexin B1, expressed on endothelial cells (Conrotto, P., D. Valdembri, S. Corso, G. Serini, L. Tamagnone, P.M. Comoglio, F. Bussolino, and S. Giordano. 2005. Blood. 105:4321 - 4329). The present work highlights the role of Sema4D produced by the tumor microenvironment on neoplastic angiogenesis. We show that in an environment lacking Sema4D, the ability of cancer cells to generate tumor masses and metastases is severely impaired. This condition can be explained by a defective vascularization inside the tumor. We demonstrate that tumor-associated macrophages (TAMs) are the main cells producing Sema4D within the tumor stroma and that their ability to produce Sema4D is critical for tumor angiogenesis and vessel maturation. This study helps to explain the protumoral role of infiammatory cells of the tumor stroma and leads to the identification of an angiogenic molecule that might be a novel therapeutic target

    The tumor suppressor semaphorin 3B triggers a prometastatic program mediated by interleukin 8 and the tumor microenvironment

    No full text
    Semaphorins are a large family of evolutionarily conserved morphogenetic molecules originally identified for their repelling role in axonal guidance. Intriguingly, semaphorins have recently been implicated in cancer progression (Neufeld, G., T. Lange, A. Varshavsky, and O. Kessler. 2007. Adv. Exp. Med. Biol. 600:118-131). In particular, semaphorin 3B (SEMA3B) is considered a putative tumor suppressor, and yet we found that it is expressed at high levels in many invasive and metastatic human cancers. By investigating experimental tumor models, we confirmed that SEMA3B expression inhibited tumor growth, whereas metastatic dissemination was surprisingly increased. We found that SEMA3B induced the production of interleukin (IL) 8 by tumor cells by activating the p38-mitogen-activated protein kinase pathway in a neuropilin 1-dependent manner. Silencing the expression of endogenous SEMA3B in tumor cells impaired IL-8 transcription. The release of IL-8, in turn, induced the recruitment of tumor-associated macrophages and metastatic dissemination to the lung, which could be rescued by blocking IL-8 with neutralizing antibodies. In conclusion, we report that SEMA3B exerts unexpected functions in cancer progression by fostering a prometastatic environment through elevated IL-8 secretion and recruitment of macrophages coupled to the suppression of tumor growth. © 2008 Rolny et al. The Rockefeller University Press
    corecore