奥沙利铂治疗肝细胞癌耐药的相关机制研究进展

奥沙利铂在我国已被批准用于晚期肝细胞癌（HCC）的治疗,以奥沙利铂为基础的FOLFOX 4方案已成为晚期HCC的标准治疗之一,显著延长了患者的生存期,展现出安全有效、耐受性良好等特点。尽管如此,奥沙利铂治疗HCC的临床疗效仍十分有限,其治疗失败与HCC产生耐药密切相关。本文就奥沙利铂治疗HCC的耐药机制研究进展作一综述,希望能帮助临床和科研工作者了解最新动态,并为他们的工作拓宽思路。     

Secretory clusterin contributes to oxaliplatin resistance by activating Akt pathway in hepatocellular carcinoma

Secretory clusterin (sCLU) is expressed in numerous cancers and is associated with the resistance to chemotherapy. However, the role of sCLU in the resistance of hepatocellular carcinoma (HCC) to oxaliplatin (OXA), a recently used third‐generation platinum agent, remains unclear. The stable transfectants that are depleted of or overexpress sCLU and OXA‐resistant cells were generated using human HCC cells. Overexpression of sCLU abrogated OXA‐induced inhibition of cell growth and cell apoptosis, but depletion of sCLU synergized with OXA to inhibit cell growth and enhance cell apoptosis, by regulating proteins involved in mitochondrial apoptosis pathways, such as Bcl‐2, Bax, Bcl‐xL and caspase‐9, and affecting phosphorylation of Akt and GSK‐3β. Overexpression of sCLU in either OXA‐resistant cells or stable transfectants that overexpress sCLU significantly increased phosphorylated Akt. However, specific inhibition of Akt enhanced sensitivity of sCLU‐overexpressing cells to OXA, but had no effect on sCLU expression, suggesting that the regulatory effects between sCLU and pAkt may be in a one‐way manner in HCC cells. The expression levels of sCLU affected the therapeutic efficacy of OXA to treat HCC tumors established in immunodeficiency mice. The results have demonstrated that sCLU contributes to OXA resistance by activating Akt pathway, indicating that sCLU may be a novel molecular target for overcoming OXA resistance in HCC.     

长链非编码RNA LINC00601调控肝细胞癌奥沙利铂耐药的分子机制研究

背景与目的：肝细胞癌（hepatocellular carcinoma,HCC）仍是当今中国乃至全世界的高发肿瘤之一,大部分HCC患者确诊时处于中晚期,对化疗耐药或介入治疗抵抗是影响此类患者生存预后的重要因素,但其中涉及的具体分子机制尚未完全明确。我们的前期研究发现长链非编码RNA LINC00601在奥沙利铂耐药的HCC细胞中高表达。本研究旨在探索LINC00601调控HCC细胞对奥沙利铂化疗耐药的作用及其机制,为临床筛选适宜接受奥沙利铂化疗的HCC患者并为中晚期HCC患者的治疗提供新的靶点和理论依据。方法：利用体外长期低剂量奥沙利铂刺激人HCC细胞株MHCC-97H和Hep-3B,建立奥沙利铂耐药细胞株97H-OXR和3B-OXR。采用实时荧光定量聚合酶链反应（real-timefluorescencequantitative polymerase chain reaction,RTFQ-PCR）检测奥沙利铂耐药细胞株中LINC00601的表达情况。进一步采用细胞计数试剂盒-8(cell counting kit-8,CCK-8)实验检测LINC00601基因沉默或过表达对HCC细...     

Restoration of klotho expression induces apoptosis and autophagy in hepatocellular carcinoma cells

Purpose

Klotho has been identified as a tumor suppressor in several human malignancies including hepatocellular carcinoma (HCC). However, the signaling pathways involved in the tumor suppressive role of klotho in HCC have not been reported. Here, we investigated the role of klotho in HCC cell proliferation, apoptosis, autophagy, and invasion, as well as its associated signal transduction pathways.

Methods

Restoration of klotho gene expression was established by delivering a klotho gene expression vector into the human HCC cell lines HepG2 and MHCC-97-H. Cell viability was measured using a cell counting (CCK-8) assay and apoptosis was analyzed through flow cytometry. Autophagy was measured via LC3-I and LC3-II protein expression levels and tumor cell invasion was assessed using a Matrigel invasion chamber assay. Expression and phosphorylation of several apoptosis and survival related proteins were assessed using Western blot assays.

Results

Exogenous klotho gene expression significantly inhibited HCC cell proliferation, induced HCC cell apoptosis, increased LC3-I and LC3-II protein expression in HCC cells, and decreased migration of HCC cells in a Matrigel invasion chamber assay. Exogenous klotho gene expression also down-regulated the phosphorylation levels of the IGF-1 receptor, and the downstream Akt, ERK, and p70S6K proteins. Both apoptosis and autophagy inhibitors decreased klotho-induced apoptosis and autophagy.

Conclusion

Klotho is a tumor suppressor that, through the regulation of IGF-1R phosphorylation and subsequent activation of downstream Akt-p70S6K and ERK signaling, regulates HCC tumor cell proliferation, apoptosis, autophagy and invasion.     

Interferon-alpha-2b induces autophagy in hepatocellular carcinoma cells through Beclinl pathway

Objeαive： To determine whether Interferon-alpha-2b （IFN-α2b） can modulate the autophagic response in hepatocellular carcinoma cells. Methods： Hepatocellular carcinoma cells were treated with IFN-α2b. Autophagy was assessed by acridine orange staining, GFP-LC3 dotted assay, transmission eleαron microscopy and immunoblotting. Results： Acridine orange staining showed that IFN-α2b triggered the accumulation of acidic vesicular and autolysosomes in HepG2 cells. The acridine orange HepG2 cell ratios were （4.3±1.0）%, （6.9±1.4）%, and （13.1±2.3）%, respeαively, after treatment with 100, 1,000, and 10,000 IU/mL IFN-α2b for 48 h. A markedly punαate pattern was observed in HepG2 cells treated with 10,000 IU/mL [FN-α2b for 48 h, but only diffuse and weakly fluorescent GFP-LC3 punαa was observed in control cells. HepG2 cells treated with 10,000 IU/mL IFN-α2b for 48 h developed autophagosome-like charaαeristics, including single- or double-membrane vacuoles containing intaα and degraded cellular debris. The Beclinl and LC3-II protein expression was up-regulated by IFN-α2b treatment. Conclusion： Autophagy can be induced in a dose-dependent manner by treatment with IFN-α2b in HepG2 cells, and the Beclinl signaling pathway was stimulated by IFN-α2b.     

MiR-21 mediates sorafenib resistance of hepatocellular carcinoma cells by inhibiting autophagy via the PTEN/Akt pathway

Sorafenib resistance remains a major obstacle for the effective treatments of hepatocellular carcinoma (HCC). Recent studies indicate that activated Akt contributes to the acquired resistance to sorafenib, and miR-21 dysregulates phosphatase and tensin homolog (PTEN), which inhibits Akt activation. Sorafenib-resistant HCC cells were shown to be refractory to sorafenib-induced growth inhibition and apoptosis. Akt and its downstream factors were highly activated and/or upregulated in sorafenib-resistant cells. Inhibition of autophagy decreased the sensitivity of sorafenib-resistant cells to sorafenib, while its induction had the opposite effect. Differential screening of miRNAs showed higher levels of miR-21 in sorafenib-resistant HCC cells. Exposure of HCC cells to sorafenib led to an increase in miR-21 expression, a decrease in PTEN expression and sequential Akt activation. Transfection of miR-21 mimics in HCC cells restored sorafenib resistance by inhibiting autophagy. Anti-miR-21 oligonucleotides re-sensitized sorafenib-resistant cells by promoting autophagy. Inhibition of miR-21 enhances the efficacy of sorafenib in treating sorafenib-resistant HCC tumors in vivo. We conclude that miR-21 participates in the acquired resistance of sorafenib by suppresing autophagy through the Akt/PTEN pathway. MiR-21 could serve as a therapeutic target for overcoming sorafenib resistance in the treatment of HCC.     

Interferon-alpha-2b induces autophagy in hepatocellular carcinoma cells through Beclin1 pathway

Objective

To determine whether Interferon-alpha-2b (IFN-α2b) can modulate the autophagic response in hepatocellular carcinoma cells.

Methods

Hepatocellular carcinoma cells were treated with IFN-α2b. Autophagy was assessed by acridine orange staining, GFP-LC3 dotted assay, transmission electron microscopy and immunoblotting.

Results

Acridine orange staining showed that IFN-α2b triggered the accumulation of acidic vesicular and autolysosomes in HepG2 cells. The acridine orange HepG2 cell ratios were (4.3±1.0)%, (6.9±1.4)%, and (13.1±2.3)%, respectively, after treatment with 100, 1,000, and 10,000 IU/mL IFN-α2b for 48 h. A markedly punctate pattern was observed in HepG2 cells treated with 10,000 IU/mL IFN-α2b for 48 h, but only diffuse and weakly fluorescent GFP-LC3 puncta was observed in control cells. HepG2 cells treated with 10,000 IU/mL IFN-α2b for 48 h developed autophagosome-like characteristics, including single- or double-membrane vacuoles containing intact and degraded cellular debris. The Beclin1 and LC3-II protein expression was up-regulated by IFN-α2b treatment.

Conclusion

Autophagy can be induced in a dose-dependent manner by treatment with IFN-α2b in HepG2 cells, and the Beclin1 signaling pathway was stimulated by IFN-α2b.KEYWORDS : Interferon-alpha-2b (IFN-α2b), autophagy, acridine orange, Beclin1, transmission electron microscopy     

含笑内酯通过促进自噬增强结直肠癌细胞对奥沙利铂的敏感性

目的:研究含笑内酯(micheliolide,MCL)对结直肠癌细胞奥沙利铂(oxaliplatin,OxP)敏感性的影响及其可能的作用机制.方法:采用2 μmol/L MCL、100 μmol/L OxP单独或联合处理结直肠癌HCT116、Lovo细胞,CCK-8法、平板克隆实验分别检测对细胞活力和体外克隆形成能力的...     

微小RNA在肝细胞癌及肝癌干细胞中的作用

微小RNA (miRNA)是一类约22个核苷酸分子构成的非编码单链小RNA.miRNA能参与一系列重要的生物学活动,如早期胚胎与器官发育、细胞增殖与分化、细胞凋亡等.miRNA在肝细胞癌中表达异常,与肝癌发生发展和浸润转移密切相关.肝癌干细胞可能是肝癌复发和转移的根源,某些miRNA与肝癌干细胞的自我更新、多向分化及成...     

蟾蜍灵诱导人胃癌SGC7901细胞自噬与凋亡的研究

目的：探讨自噬在蟾蜍灵（bufalin）诱导人胃癌SGC7901细胞死亡中的作用.方法：不同浓度的bu-falin处理人胃癌SGC7901细胞,采用MTT法检测bufalin对SGC7901细胞增殖的抑制作用.透射电镜观察给药后SGC7901细胞的自噬现象;流式细胞术检测细胞凋亡.Western blot检测自噬标志LC3蛋白表达.结果：Bufalin对胃癌SGC7901细胞生长有显著的抑制作用,且此作用呈明显的时间-剂量依赖性.Bufalin给药后可诱导SGC7901细胞发生自噬;并且在bufalin给药前用氯喹阻断自噬明显提高了bufalin对SGC7901的细胞毒性（P＜0.05）.结论：Bufalin能明显抑制SGC7901细胞的生长,并且诱导其发生保护性自噬.Bufalin和自噬抑制剂的联合应用可能为胃癌治疗提供新的策略.     

Mitochondrial cholesterol contributes to chemotherapy resistance in hepatocellular carcinoma

Cholesterol metabolism is deregulated in carcinogenesis, and cancer cells exhibit enhanced mitochondrial cholesterol content whose role in cell death susceptibility and cancer therapy has not been investigated. Here, we describe that mitochondria from rat or human hepatocellular carcinoma (HC) cells (HCC) or primary tumors from patients with HC exhibit increased mitochondrial cholesterol levels. HCC sensitivity to chemotherapy acting via mitochondria is enhanced upon cholesterol depletion by inhibition of hydroxymethylglutaryl-CoA reductase or squalene synthase (SS), which catalyzes the first committed step in cholesterol biosynthesis. HCC transfection with siRNA targeting the steroidogenic acute regulatory protein StAR, a mitochondrial cholesterol-transporting polypeptide which is overexpressed in HCC compared with rat and human liver, sensitized HCC to chemotherapy. Isolated mitochondria from HCC with increased cholesterol levels were resistant to mitochondrial membrane permeabilization and release of cytochrome c or Smac/DIABLO in response to various stimuli including active Bax. Similar behavior was observed in cholesterol-enriched mitochondria or liposomes and reversed by restoring mitochondrial membrane order or cholesterol extraction. Moreover, atorvastatin or the SS inhibitor YM-53601 potentiated doxorubicin-mediated HCC growth arrest and cell death in vivo. Thus, mitochondrial cholesterol contributes to chemotherapy resistance by increasing membrane order, emerging as a novel therapeutic niche in cancer therapy.     

High-LET radiation combined with oxaliplatin induce autophagy in U-87 glioblastoma cells

Modern protocols of concomitant chemo/radiotherapy provide a very effective strategy to treat certain types of tumors. High-linear energy transfer (LET) radiations, on the other hand, have an increased efficacy against cancer with low radiosensibility and critical localization. We previously reported that oxaliplatin, a third generation platinum drug, was able to reinforce the cytotoxicity of an irradiation by fast neutrons towards human glioblastoma U-87 cells in culture. We show here that such a combination has the capacity to enhance the number of double strand breaks in DNA and to induce autophagy in these cells. Xenografts experiments were further performed in nude mice subcutaneously transplanted with U-87 cells. When injected shortly before a single irradiation by fast neutrons, oxaliplatin causes a marked reduction of tumor growth compared with the irradiation alone. Overall, our data indicate the unique cytotoxic mechanism of a combined high-LET irradiation and oxaliplatin treatment modality and suggest its potential application in anticancer therapy.     

Nitric oxide inhibits autophagy and promotes apoptosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second most common cause of cancer‐related mortality worldwide. The expression of nitric oxide synthase (NOS) and the inhibition of autophagy have been linked to cancer cell death. However, the involvement of serum nitric oxide (NO), the expression of NOS and autophagy have not been investigated in HCC. In the present study, we first established that the NO level was significantly higher in hepatitis B virus‐related HCC than in the liver cirrhosis control (53.60 ± 19.74 vs 8.09 ± 4.17 μmol/L, t = 15.13, P < 0.0001). Using immunohistochemistry, we found that the source of NO was at least partially attributed to the expression of inducible NOS and endothelial NOS but not neuronal NOS in the liver tissue. Furthermore, in human liver cancer cells, NO‐induced apoptosis and inhibited autophagy. Pharmacological inhibition of autophagy also induced apoptosis, whereas the induction of autophagy could ameliorate NO‐induced apoptosis. We also found that NO regulates the switch between apoptosis and autophagy by disrupting the Beclin 1/Vps34 association and by increasing the Bcl‐2/Beclin 1 interaction. Overall, the present findings suggest that increased NOS/NO promotes apoptosis through the inhibition of autophagy in liver cancer cells, which may provide a novel strategy for the treatment of HCC.     

中期因子诱导肝癌细胞Hep3B抵抗失巢凋亡

目的：探讨肝素结合分子中期因子（midkine,MK）对肝癌细胞Hep3B抵抗失巢凋亡的影响。方法：采用悬浮培养法建立人肝癌来源细胞系Hep3B失巢凋亡模型,以不同质量浓度（10、50、100 ng/ml）MK或PBS（对照组）处理失巢培养的肝癌细胞Hep3B,采用流式细胞术检测Hep3B细胞的凋亡,采用Western blotting检测凋亡相关蛋白Bcl-2和caspase-3的表达。结果：随着悬浮培养时间的延长,肝癌细胞Hep3B失巢凋亡率逐渐升高,培养72 h后悬浮培养的Hep3B细胞凋亡率显著高于贴壁培养的Hep3B细胞凋亡率\[（38.76±4.23）% vs （6.76±1.43）%,P<0.01\]。不同质量浓度MK处理24 h后,悬浮培养Hep3B细胞的凋亡率均明显低于对照组,且与MK的浓度呈负相关关系（r=0.951,P=0.049）;同时,MK处理后Hep3B细胞内抗凋亡蛋白Bcl-2表达明显增加,而促凋亡蛋白caspase-3则明显下降。结论：MK可能通过上调Bcl-2蛋白表达和下调caspase-3蛋白的表达来提高肝癌细胞Hep3B在失巢状态下抵抗凋亡的能力。     

Antimicrobial peptaibols,novel suppressors of tumor cells,targeted calcium-mediated apoptosis and autophagy in human hepatocellular carcinoma cells

Background  

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world which is highly chemoresistant to currently available chemotherapeutic agents. Thus, novel therapeutic targets are needed to be sought for the successful treatment of HCC. Peptaibols, a family of peptides synthesized non-ribosomally by the Trichoderma species and other fungi, exhibit antibiotic activities against bacteria and fungi. Few studies recently showed that peptaibols exerted cytotoxicity toward human lung epithelial and breast carcinoma cells. However, the mechanism involved in peptaibol-induced cell death remains poorly understood.     

Emerging role of autophagy during ischemia-hypoxia and reperfusion in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary malignancy found in the liver. Autophagy is the intracellular bulk degradation process for long-lived proteins and dysfunctional organelles. In this study, we report that autophagy plays a role in HCC cell proliferation in response to ischemia-hypoxia (I/H) and reperfusion and discuss its potential therapeutic implications. By establishing a simulated model in cultured HepG2 (p53 wild-type) and Hep3B (p53 null) hepatoma cells in vitro, we found that exposure to I/H induced a significant increase in microtubule-associated protein 1 light chain 3 (LC3) lipidation and subsequent LC3 puncta formation. While the proliferation of HCC cells was stimulated upon acute I/H exposure compared to that of control, inhibition of autophagy by autophagy-related protein 7 interference abolished it. In addition, the steady-state levels of sequestosome 1 (p62) in both HepG2 and Hep3B cells were reduced following I/H exposure, supporting the notion that acute I/H induces autophagy. Intriguingly, the p62 level further decreased during reperfusion following I/H, accompanied by increased LC3 lipidation. The intracellular reactive oxygen species (ROS) accumulated during acute I/H exposure and persisted through reperfusion in both HepG2 and Hep3B cells and the ROS levels increased at a much faster rate during reperfusion than during I/H periods in both cells. Autophagy functions as a promoter for HCC cell survival during acute I/H and reperfusion and this also points to potential therapy for hepatoma by perturbing the acute I/H-reperfusion-autophagy axis.     

Inhibiting CBX4 efficiently protects hepatocellular carcinoma cells against sorafenib resistance

Background This study aimed to investigate the possible role of inhibiting chromobox protein homologue 4 (CBX4) to deregulate of cancer stem cells (CSCs) and to evaluate the contribution of these molecules to sorafenib resistance in advanced hepatocellular carcinoma (HCC).Methods HCC cell lines and a xenograft mouse model with resistance to sorafenib were employed to analyse the effects of miR424 on CSC characteristics. RNA expression was analysed by RT-PCR and next-generation sequencing in a cohort of HCC cancer patients and sorafenib-resistant (SR) cell lines, respectively, to validate the key microRNAs and targets in the network.Results MicroRNA and mRNA profiles of SR cell lines identified miR424 and its direct target CBX4 as significantly associated with stem-cell-like properties, poor survival, and clinical characteristics. Functional experiments demonstrated that miR424 suppressed CBX4 and CBX4 induced nuclear translocation of YAP1 protein but was not associated with protein production. When YAP1 and CBX4 were modulated with CA3 and UNC3866, tumorigenicity and stem-like properties were extremely inhibited, thus indicating that these compounds exerted a strong anti-tumour effect in vivo against SR HCC cells.Conclusions Our results revealed that blocking CBX4 expression is critical in response to sorafenib resistance with advanced HCC.Subject terms: Hepatocellular carcinoma, Nuclear receptors