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High mobility group box 1 promotes sorafenib resistance in HepG2 cells and in vivo.

ABSTRACT: Primary liver cancer is a lethal malignancy with a high mortality worldwide. Currently, sorafenib is the most effective molecular-targeted drug against hepatocellular carcinoma (HCC). However, the sorafenib resistance rate is high. The molecular mechanism of this resistance has not been fully elucidated. High mobility group box 1 (HMGB1) is a multifaceted protein that plays a key role in the proliferation, apoptosis, metastasis and angiogenesis of HCC cells. In addition, HMGB1 has been suggested to contribute to chemotherapy resistance in tumours, including lung cancer, osteosarcoma, neuroblastoma, leukaemia, and colorectal cancer. This study investigated the association between HMGB1 and sorafenib resistance in HCC.HepG2 cells with HMGB1 knockdown or overexpression were generated. The efficacy of sorafenib in these cells was tested using flow cytometry and a cell counting assay. The subcellular localization of HMGB1 in HepG2 cells following sorafenib treatment was measured by western blotting and confocal microscopy. A murine subcutaneous HCC model was generated to examine the association between HMGB1 and the sensitivity of sorafenib treatment.The HMGB1 knockdown cells exhibited a significantly higher apoptotic level and lower cell viability than the normal HMGB1 expressing cells following the sorafenib treatment. In addition, the cell viability observed in the HMGB1 overexpressing cells was higher than that observed in the control cells following the sorafenib intervention. Sorafenib had a better tumour inhibition effect in the HMGB1 knockdown group in vivo. The amount of mitochondrial HMGB1 decreased, while the amount of cytosolic HMGB1 increased following the exposure to sorafenib. Altogether, HMGB1 translocated from the mitochondria to the cytoplasm outside the mitochondria following the exposure of HepG2 cells to sorafenib.A novel potential role of HMGB1 in the regulation of sorafenib therapy resistance in HCC was observed. The knockdown of HMGB1 restores sensitivity to sorafenib and enhances HepG2 cell death, while HMGB1 overexpression blunts these effects. The translocation of HMGB1 from the mitochondria to the cytosol following sorafenib treatment provides new insight into sorafenib resistance in HCC.

SUBMITTER: Xiao Y

PROVIDER: S-EPMC5731191 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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High mobility group box 1 promotes sorafenib resistance in HepG2 cells and in vivo.

Xiao Yinzong Y Sun Lunquan L Fu Yongming Y Huang Yan Y Zhou Rongrong R Hu Xingwang X Zhou Pengcheng P Quan Jun J Li Ning N Fan Xue-Gong XG

BMC cancer 20171215 1

<h4>Background</h4>Primary liver cancer is a lethal malignancy with a high mortality worldwide. Currently, sorafenib is the most effective molecular-targeted drug against hepatocellular carcinoma (HCC). However, the sorafenib resistance rate is high. The molecular mechanism of this resistance has not been fully elucidated. High mobility group box 1 (HMGB1) is a multifaceted protein that plays a key role in the proliferation, apoptosis, metastasis and angiogenesis of HCC cells. In addition, HMGB1 ...[more]

PMID: 29246127

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Project description:Myeloid-derived suppressor cells are immune-suppressive cells that are elevated in most individuals with cancer, where their accumulation and suppressive activity are driven by inflammation. As myeloid-derived suppressor cells inhibit anti-tumor immunity and promote tumor progression, we are determining how their viability is regulated. Previous studies have established that the damage-associated molecular pattern molecule high-mobility group box protein 1 drives myeloid-derived suppressor cell accumulation and suppressive potency and is ubiquitously present in the tumor microenvironment. As high-mobility group box protein 1 also facilitates tumor cell survival by inducing autophagy, we sought to determine if high-mobility group box protein 1 regulates myeloid-derived suppressor cell survival through induction of autophagy. Inhibition of autophagy increased the quantity of apoptotic myeloid-derived suppressor cells, demonstrating that autophagy extends the survival and increases the viability of myeloid-derived suppressor cells. Inhibition of high-mobility group box protein 1 similarly increased the level of apoptotic myeloid-derived suppressor cells and reduced myeloid-derived suppressor cell autophagy, demonstrating that in addition to inducing the accumulation of myeloid-derived suppressor cells, high-mobility group box protein 1 sustains myeloid-derived suppressor cell viability. Circulating myeloid-derived suppressor cells have a default autophagic phenotype, and tumor-infiltrating myeloid-derived suppressor cells are more autophagic, consistent with the concept that inflammatory and hypoxic conditions within the microenvironment of solid tumors contribute to tumor progression by enhancing immune-suppressive myeloid-derived suppressor cells. Overall, these results demonstrate that in addition to previously recognized protumor effects, high-mobility group box protein 1 contributes to tumor progression by increasing myeloid-derived suppressor cell viability by driving them into a proautophagic state.

Project description:BackgroundCancer-associated fibroblasts and high mobility group box 1 (HMGB1) protein have been suggested to mediate cancer progression and chemotherapy resistance. The role of such fibroblasts in HMGB1 production in breast cancer is unclear. This study aimed to investigate the effects of cancer-associated fibroblasts on HMGB1 expression in breast cancer cells and its role in chemotherapeutic response.MethodsBreast cancer-associated fibroblasts (BCFs) and non-tumor-associated fibroblasts (NTFs) were isolated from human breast cancers or adjacent normal tissues and established as primary cultures in vitro. After confirmation of the activated status of these fibroblasts, conditioned-media (CM) were collected and applied to MDA-MB-231 human triple negative breast cancer cells. The levels of intracellular and extracellular HMGB1 were measured by real-time PCR and/or Western blot. The response of BCF-CM-pre-treated cancer cells to doxorubicin (Dox) was compared with those pre-treated with NTF-CM or control cultures. The effect of an HMGB1 neutralizing antibody on Dox resistance induced by extracellular HMGB1 from non-viable Dox-treated cancer cells or recombinant HMGB1 was also investigated.ResultsImmunocytochemical analysis revealed that BCFs and NTFs were alpha-smooth muscle actin (ASMA) positive and cytokeratin 19 (CK19) negative cells: a phenotype consistent with that of activated fibroblasts. We confirmed that the CM from BCFs (but not NTFs), could significantly induce breast cancer cell migration. Intracellular HMGB1 expression was induced in BCF-CM-treated breast cancer cells and also in Dox-treated cells. Extracellular HMGB1 was strongly expressed in the CM after Dox-induced MDA-MB-231 cell death and was higher in cells pre-treated with BCF-CM than NTF-CM. Pre-treatment of breast cancer cells with BCF-CM induced a degree of resistance to Dox in accordance with the increased level of secreted HMGB1. Recombinant HMGB1 was shown to increase Dox resistance and this was associated with evidence of autophagy. Anti-HMGB1 neutralizing antibody significantly reduced the effect of extracellular HMGB1 released from dying cancer cells or of recombinant HMGB1 on Dox resistance.ConclusionsThese findings highlight the potential of stromal fibroblasts to contribute to chemoresistance in breast cancer cells in part through fibroblast-induced HMGB1 production.

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High mobility group box 1 promotes sorafenib resistance in HepG2 cells and in vivo.

Publications

High mobility group box 1 promotes sorafenib resistance in HepG2 cells and in vivo.

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