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Sirtuin 6 promotes transforming growth factor-?1/H2O2/HOCl-mediated enhancement of hepatocellular carcinoma cell tumorigenicity by suppressing cellular senescence.

ABSTRACT: Sirtuin 6 (SIRT6) can function as a tumor suppressor by suppressing aerobic glycolysis and apoptosis resistance. However, the negative effect of SIRT6 on cellular senescence implies that it may also have the potential to promote tumor development. Here we report that the upregulation of SIRT6 expression was required for transforming growth factor (TGF)-?1 and H2O2/HOCl reactive oxygen species (ROS) to promote the tumorigenicity of hepatocellular carcinoma (HCC) cells. Transforming growth factor-?1/H2O2/HOCl could upregulate SIRT6 expression in HCC cells by inducing the sustained activation of ERK and Smad pathways. Sirtuin 6 in turn abrogated the inducing effect of TGF-?1/H2O2/HOCl on cellular senescence of HCC cells, and was required for the ERK pathway to efficiently suppress the expression of p16 and p21. Sirtuin 6 altered the effect of Smad and p38 MAPK pathways on cellular senescence, and contributed to the inhibitory effect of the ERK pathway on cellular senescence. However, SIRT6 was inefficient in antagonizing the promoting effect of TGF-?1/H2O2 HOCl on aerobic glycolysis and anoikis resistance. Intriguingly, if SIRT6 expression was inhibited, the promoting effect of TGF-?1/H2O2/HOCl on aerobic glycolysis and anoikis resistance was not sufficient to enhance the tumorigenicity of HCC cells. Suppressing the upregulation of SIRT6 enabled TGF-?1/H2O2/HOCl to induce cellular senescence, thereby abrogating the enhancement of HCC cell tumorigenicity by TGF-?1/H2O2/HOCl. These results suggest that SIRT6 is required for TGF-?1/H2O2/HOCl to enhance the tumorigenicity of HCC cells, and that targeting the ERK pathway to suppress the upregulation of SIRT6 might be a potential approach in comprehensive strategies for the therapy of HCC.

SUBMITTER: Feng XX

PROVIDER: S-EPMC4452156 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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Sirtuin 6 promotes transforming growth factor-β1/H2O2/HOCl-mediated enhancement of hepatocellular carcinoma cell tumorigenicity by suppressing cellular senescence.

Feng Xin-Xia XX Luo Jing J Liu Mei M Yan Wei W Zhou Zhen-Zhen ZZ Xia Yu-Jia YJ Tu Wei W Li Pei-Yuan PY Feng Zuo-Hua ZH Tian De-An DA

Cancer science 20150309 5

Sirtuin 6 (SIRT6) can function as a tumor suppressor by suppressing aerobic glycolysis and apoptosis resistance. However, the negative effect of SIRT6 on cellular senescence implies that it may also have the potential to promote tumor development. Here we report that the upregulation of SIRT6 expression was required for transforming growth factor (TGF)-β1 and H2O2/HOCl reactive oxygen species (ROS) to promote the tumorigenicity of hepatocellular carcinoma (HCC) cells. Transforming growth factor- ...[more]

PMID: 25683165

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Project description:The therapeutic induction of senescence is a potential means to treat cancer, primarily acting through the induction of a persistent growth-arrested state in tumors. However, recent studies have indicated that therapy-induced senescence (TIS) in tumor cells allows for the prolonged survival of a subgroup of cells in a dormant state, with the potential to re-enter the cell cycle along with an increased stemness gene expression. Residual cells after TIS with increased cancer stem cell phenotype may have profound implications for tumor aggressiveness and disease recurrence. Herein, we investigated senescence-associated stemness in EpCAM+/CD133+ liver cancer stem cell and EpCAM-/CD133- nonstem cell populations in HuH7 cell line. We demonstrated that treatment with doxorubicin induces senescence in both cell populations, accompanied by a significant increase in the expression of reprogramming genes SOX2, KLF4, and c-MYC as well as liver stemness-related genes EpCAM, CK19, and ANXA3 and the multidrug resistance-related gene ABCG2. Moreover, doxorubicin treatment significantly increased EpCAM + population in nonstem cells indicating senescence-associated reprogramming of nonstem cell population. Also, Wnt/β-catenin target genes were increased in these cells, while inhibition of this signaling pathway decreased stem cell gene expression. Importantly, Dox-treated EpCAM-/CD133- nonstem cells had increased in vivo tumor-forming ability. In addition, when SASP-CM from Dox-treated cells were applied onto hİPSC-derived hepatocytes, senescence was induced in hepatocytes along with an increased expression of TGF-β, KLF4, and AXIN2. Importantly, SASP-CM was not able to induce senescence in Hep3B-TR cells, a derivative line rendered resistant to TGF-β signaling. Furthermore, ELISA experiments revealed that the SASP-CM of Dox-treated cells contain inflammatory cytokines IL8 and IP10. In summary, our findings further emphasize the importance of carefully dissecting the beneficial and detrimental aspects of prosenescence therapy in HCC and support the potential use of senolytic drugs in HCC treatment in order to eliminate adverse effects of TIS.

Project description:BACKGROUND:Glioblastoma is devastating cancer with a high frequency of occurrence and poor survival rate and it is urgent to discover novel glioblastoma-specific antigens for the therapy. Cancer-germline genes are known to be related to the formation and progression of several cancer types by promoting tumor transformation. Dazl is one such germline gene and is up-regulated in a few germ cell cancers. In this study, we analyzed the expression of Dazl in human glioblastoma tissues and cells, and investigated its significance in proliferation, migration, invasion and chemoresistance of the glioblastoma cell lines. METHODS:We evaluated the expression of Dazl in different pathologic grades of glioblastoma tissues by immunohistochemistry. We assessed the expression of Dazl in glioblastoma cells and normal human astrocytes (NHA) cells by western blotting and RT-qPCR. Then we generated Dazl knockout glioblastoma cell lines using the CRISPR/Cas9 gene-editing technology to explore the cellular function of Dazl. We detected the proliferation and germline traits via CCK-8 assays and alkaline phosphatase staining, respectively. Boyden chamber assays were performed to measure glioblastoma cell migration and invasion. Crystal violet staining was used to determine the number of viable cells after the treatment of Doxorubicin and Temozolomide. Finally, we used subcutaneous xenograft studies to measure the growth of tumors in vivo. RESULTS:We found that Dazl was upregulated in glioblastoma tissues and glioblastoma cell lines. Dazl knockdown glioblastoma cells showed decreased cellular proliferation, migration, invasion, and resistance in vitro, and inhibited the initiation of glioblastoma in vivo. The glioblastoma cell lines A172, U251, and LN229 were found to express stem cell markers CD133, Oct4, Nanog, and Sox2. The expression of these markers was downregulated in Dazl-deficient cells. CONCLUSIONS:Our results indicated that Dazl contributes to the tumorigenicity of glioblastoma via reducing cell stemness. Therefore, cancer-germline genes might represent a new paradigm of glioblastoma-initiating cells in the treatment of malignant tumors.

Dataset Information

Sirtuin 6 promotes transforming growth factor-?1/H2O2/HOCl-mediated enhancement of hepatocellular carcinoma cell tumorigenicity by suppressing cellular senescence.

Publications

Sirtuin 6 promotes transforming growth factor-β1/H2O2/HOCl-mediated enhancement of hepatocellular carcinoma cell tumorigenicity by suppressing cellular senescence.

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