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Distinct Functions of Senescence-Associated Immune Responses in Liver Tumor Surveillance and Tumor Progression.

ABSTRACT: Oncogene-induced senescence causes hepatocytes to secrete cytokines, which induce their immune-mediated clearance to prevent tumor initiation, a process termed "senescence surveillance." However, senescent hepatocytes give rise to hepatocellular carcinomas (HCCs), if the senescence program is bypassed or if senescent cells are not cleared. Here, we show context-specific roles for CCR2⁺ myeloid cells in liver cancer. Senescence surveillance requires the recruitment and maturation of CCR2⁺ myeloid cells, and CCR2 ablation caused outgrowth of HCC. In contrast, HCC cells block the maturation of recruited myeloid precursors, which, through NK cell inhibition, promote growth of murine HCC and worsen the prognosis and survival of human HCC patients. Thus, while senescent hepatocyte-secreted chemokines suppress liver cancer initiation, they may accelerate the growth of fully established HCC.

SUBMITTER: Eggert T

PROVIDER: S-EPMC7789819 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Distinct Functions of Senescence-Associated Immune Responses in Liver Tumor Surveillance and Tumor Progression.

Eggert Tobias T Wolter Katharina K Ji Juling J Ma Chi C Yevsa Tetyana T Klotz Sabrina S Medina-Echeverz José J Longerich Thomas T Forgues Marshonna M Reisinger Florian F Heikenwalder Mathias M Wang Xin Wei XW Zender Lars L Greten Tim F TF

Cancer cell 20161001 4

Oncogene-induced senescence causes hepatocytes to secrete cytokines, which induce their immune-mediated clearance to prevent tumor initiation, a process termed "senescence surveillance." However, senescent hepatocytes give rise to hepatocellular carcinomas (HCCs), if the senescence program is bypassed or if senescent cells are not cleared. Here, we show context-specific roles for CCR2<sup>+</sup> myeloid cells in liver cancer. Senescence surveillance requires the recruitment and maturation of CC ...[more]

PMID: 27728804

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Project description:Background and aimsThe initiation of cellular senescence in response to protumorigenic stimuli counteracts malignant progression in (pre)malignant cells. Besides arresting proliferation, cells entering this terminal differentiation state adopt a characteristic senescence-associated secretory phenotype (SASP) which initiates alterations to their microenvironment and effects immunosurveillance of tumorous lesions. However, some effects mediated by senescent cells contribute to disease progression. Currently, the exploration of senescent cells' impact on the tumor microenvironment and the evaluation of senescence as possible target in colorectal cancer (CRC) therapy demand reliable detection of cellular senescence in vivo. Therefore, specific immunohistochemical biomarkers are required. Our aim is to analyze the clinical implications of senescence detection in colorectal carcinoma and to investigate the interactions of senescent tumor cells and their immune microenvironment in vitro and in vivo.MethodsSenescence was induced in CRC cell lines by low-dose-etoposide treatment and confirmed by Senescence-associated β-galactosidase (SA-β-GAL) staining and fluorescence activated cell sorting (FACS) analysis. Co-cultures of senescent cells and immune cells were established. Multiple cell viability assays, electron microscopy and live cell imaging were conducted. Immunohistochemical (IHC) markers of senescence and immune cell subtypes were studied in a cohort of CRC patients by analyzing a tissue micro array (TMA) and performing digital image analysis. Results were compared to disease-specific survival (DSS) and progression-free survival (PFS).ResultsVarying expression of senescence markers in tumor cells was associated with in- or decreased survival of CRC patients. Proximity analysis of p21-positive senescent tumor cells and cytotoxic T cells revealed a significantly better prognosis for patients in which these cell types have the possibility to directly interact. In vitro, NK-92 cells (mimicking natural killer T cells) or TALL-104 cells (mimicking both cytotoxic T cells and natural killer T cells) led to dose-dependent specific cytotoxicity in >75 % of the senescent CRC cells but <20 % of the proliferating control CRC cells. This immune cell-mediated senolysis seems to be facilitated via direct cell-cell contact inducing apoptosis and granule exocytosis.ConclusionCounteracting tumorigenesis, cellular senescence is of significant relevance in CRC. We show the dual role of senescence bearing both beneficial and malignancy-promoting potential in vivo. Absence as well as exceeding expression of senescence markers are associated with bad prognosis in CRC. The antitumorigenic potential of senescence induction is determined by tumor micromilieu and immune cell-mediated elimination of senescent cells.

Dataset Information

Distinct Functions of Senescence-Associated Immune Responses in Liver Tumor Surveillance and Tumor Progression.

Publications

Distinct Functions of Senescence-Associated Immune Responses in Liver Tumor Surveillance and Tumor Progression.

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