自噬与肿瘤耐受的关系

肿瘤是机体在各种致癌因素作用下,局部组织的某一个细胞在基因水平上失去对其生长的正常调控,导致其克隆性异常增生而形成的新生物。目前化疗和放疗是其治疗的重要手段,但一直以来,耐受性的产生成为肿瘤治疗的主要障碍。自噬是一种进化保守的溶酶体依赖的自身降解途径,越来越多的证据表明肿瘤的耐受性与自噬有关:放疗和化疗可以诱导保护性自噬的产生,帮助肿瘤细胞逃避凋亡途径。其机制可能与PI3KAkt-mTOR通路、Beclin 1、ATP、p53等有关,深入了解自噬与肿瘤耐受性之间的调控不仅为克服肿瘤细胞耐受性提供了靶点,也为自噬与凋亡关系的研究提供了线索。     

三维工程化肿瘤模型的构建及应用

肿瘤微环境指肿瘤细胞发生及转移所处的复杂三维环境。传统研究多让细胞生长在二维培养瓶或培养皿中,缺少肿瘤转移过程中复杂的细胞-细胞和细胞-基质间的动态联系,难以反映肿瘤组织的自身特点以及阐明肿瘤细胞转移的机制,也限制了有效药物的准确检测。为阐明原发性肿瘤微环境的特点,多种生物模拟的三维工程化肿瘤模型已被用于实验和临床研究,即将肿瘤基质细胞、基质组分、生物化学和生物物理学信号整合于同一个时空系统。本文总结了典型三维工程化肿瘤的构建及应用。     

死亡受体信号通路耐受机制及肿瘤治疗

死亡受体介导的凋亡通路是治疗肿瘤的理想方案。凋亡通路中具有复杂的调控机制,控制细胞的生死存亡。其中有多类抗凋亡因子,致使肿瘤细胞对凋亡信号耐受,使得凋亡在肿瘤治疗领域的应用受限。临床前体外细胞及裸鼠研究发现,单独靶向这些死亡受体或抗凋亡因子的药物或与传统化疗联合可以有效引起肿瘤细胞凋亡,但临床II期实验没有明显治疗效果。本综述总结分析多种抗凋亡因子产生的耐受机制以及靶向药物的研究现状,提出同时靶向死亡受体、c-FLIP及IAP是治疗肿瘤的理想方案。     

染色质结构蛋白变异与人类疾病

层级复杂的三维染色质结构对于细胞命运决定和功能维持所需的多种DNA相关生物学过程的时空调控至关重要,如DNA复制、转录、重组和损伤修复等.三维染色质结构失调导致基因表达异常,被认为是肿瘤或神经发育障碍等多种疾病的主要诱因.本文重点阐述组蛋白及其变体、甲基CpG结合蛋白2在三维染色质高级结构及动态性调节中的作用,总结疾病相关突变对基因功能的影响,探讨肿瘤或神经发育障碍发生发展过程中染色质层面的病理学机制.     

死亡受体信号通路耐受机制及肿瘤治疗CSCD

死亡受体介导的凋亡通路是治疗肿瘤的理想方案。凋亡通路中具有复杂的调控机制,控制细胞的生死存亡。其中有多类抗凋亡因子,致使肿瘤细胞对凋亡信号耐受,使得凋亡在肿瘤治疗领域的应用受限。临床前体外细胞及裸鼠研究发现,单独靶向这些死亡受体或抗凋亡因子的药物或与传统化疗联合可以有效引起肿瘤细胞凋亡,但临床II期实验没有明显治疗效果。本综述总结分析多种抗凋亡因子产生的耐受机制以及靶向药物的研究现状,提出同时靶向死亡受体、c-FLIP及IAP是治疗肿瘤的理想方案。     

单细胞测序技术在肝癌研究中的应用

传统的细胞遗传信息研究方法是对大量混合细胞进行高通量测序,得到一群细胞基因表达的平均值,忽视了细胞间存在的异质性。肝癌作为一种人类常见的恶性致命肿瘤,其内部肿瘤细胞存在高度异质性,群体水平分析无法精确揭示其恶性细胞克隆结构和免疫微环境的细胞种类、状态和亚群分布,因此迫切需要进行单细胞水平的分析,这将有助于深入了解肝癌发病机制,进行精准肝癌分型指导临床治疗。同时发现,新型治疗靶点及有效生物标记物,为肝癌患者今后进行精准诊疗提供参考。本文综述了单细胞基因组和转录物组测序技术在肝癌免疫微环境、肝癌细胞异质性、肝癌细胞演化与诊疗和肝癌转移机制及生物标志物研究中的应用。本文还总结了在肝癌研究中,单细胞多组学测序技术在发现新肿瘤亚群、精确识别肿瘤细胞间的异质性和了解肿瘤微环境构成等方面的优势。     

长春新碱诱导建立人结肠癌多药耐受性小鼠模型及MDR1和MRP1基因表达

目的建立人结肠癌多药耐受性动物模型并初步探索其耐药机制。方法结合体内外诱导方法建立人结肠癌多药耐受性动物模型,利用VCR和CTX的肿瘤抑制实验评价其MDR特性;利用real-time PCR和West-ern blotting等方法分析其P-gp/MDR1和MRP1基因和蛋白的表达。结果肿瘤抑制实验结果显示,MDR和敏感型结肠癌模型的肿瘤生长速度差异不显著,MDR结肠癌动物模型对于VCR和CTX的耐药性均有较大程度的提高;表达分析结果显示,人结肠癌MDR动物模型的P-gp/MDR1表达水平有较大提高,而MRP1表达没有显著变化。结论人结肠癌多药耐受性动物模型具有较好的多药耐受性,其多药耐受性表型主要是由于P-gp/MDR1过量表达所导致。     

《生物制造》:世界首个体外三维肿瘤模型构建成功

<正>清华大学机械工程系"千人计划"特聘教授孙伟课题组运用自主开发的细胞三维打印技术,在世界上首次构建出Hela细胞(一种子宫颈癌细胞)的体外三维肿瘤模型。相关研究发表于最新一期的《生物制造》(Biofabrication),英国广播公司也对此成果进行了报道,并称之为"令人着迷的技术进展"。据了解,三维打印构建的癌细胞三维结构能够更好地反映体内肿瘤的生长和发育情况,是一种更接近体内癌细胞病变特性的肿瘤模型。其对     

酪氨酸磷酸酶PRL-3增加胃癌细胞BGC823的SP细胞比例并提高其对化疗药物的耐受性

蛋白酪氨酸磷酸酶PRL-3是近年发现的蛋白酪氨酸磷酸酶家族成员,能促进肿瘤细胞的侵袭、转移及上皮细胞间质转型,提示PRL-3可能在肿瘤发生发展及诱导肿瘤干细胞生成中发挥重要作用.由于侧群(SP)细胞具有许多干细胞的性质,SP细胞分选是目前筛选和分离获得干细胞或前体细胞常用的有效方法.为探讨PRL-3在诱导干细胞生成中的潜在作用,本文在建立过表达PRL-3的人胃癌细胞BGC823的基础上,通过SP分选和CCK-8的方法分析PRL-3对BGC823细胞中SP细胞的比例以及对化疗药物耐受性的影响.结果提示,高表达PRL-3提高BGC823中SP细胞的比例（2.5% vs 9.4%）,同时增加BGC823对化疗药物紫杉醇和顺铂的耐受性（相对于对照细胞,其耐药指数分别为1.75和1.29）.由于SP细胞的产生和细胞耐药性的提高与ABC家族基因表达水平上调密切相关,通过定量 RT-PCR和Western印迹检测发现,PRL-3能上调ABCB1和ABCG2的表达.上述研究结果表明,PRL-3有可能通过上调ABCB1和ABCG2的表达,增加胃癌细胞BGC823的SP细胞比例并增加其对化疗药物的耐受性.     

研发动态

<正>清华大学和中国医科院打印出世界首个体外肿瘤模型清华大学机械工程系特聘教授孙伟课题组与中国医学科学院肿瘤医院程书钧院士课题组合作,运用自主开发的细胞三维打印技术,在世界上首次构建出Hela细胞(一种子宫颈癌细胞)的体外三维肿瘤模型。相关研究发表于最新一期的《生物制造》杂志。三维打印构建的癌细胞三维结构能够更好地反映体内肿瘤的生长和发     

Identification of three gene candidates for multicellular resistance in colon carcinoma

Solid tumours display elevated resistance to chemo- and radiotherapies compared to individual tumour derived cells. This so-called multicellular resistance (MCR) phenomenon can only be partly explained by reduced diffusion and altered cell cycle status; even fast growing cells on the surface of solid tumours display MCR. Multicellular spheroids (MCS) recapture this phenomenon ex vivo and here we compare gene expression in exponentially growing MCS with gene expression in monolayer culture. Using an 18,664 gene microarray, we identified 42 differentially expressed genes and three of these genes can be linked to potential mechanisms of MCR. A group of interferon response genes were also up-regulated in MCS, as were a number of genes that that are indicative of greater differentiation in three-dimensional cultures.     

Intrinsic or acquired drug resistance and metastasis: Are they linked phenotypes?

Evidence is reviewed which suggests a linkage may exist between certain forms of de novo or acquired drug resistance and metastasis. This includes finding that expression of certain dominantly acting mutant oncogenes or tumor suppressor genes, e.g. genes which normally act to “drive” tumor progression and metastasis, can also affect the expression of drug resistance. Moreover, this can be accompanied by altered expression of certain cellular genes thought to be involved in expression of drug resistance. A direct linkage between acquired drug resistance and metastasis would suggest that tumor sublines selected for drug resistance should manifest more aggressive malignant properties than their drug-sensitive counterparts. While this does not appear to be true for drug resistant sublines selected in vitro, indeed such cell lines frequently manifest diminished in vivo tumorigenic and/or metastatic competence, there is some evidence to support such a correlation exists for tumor cell lines that are selected in vivo for drug resistance. Attention is also drawn to the fact that new linkages between metastasis and drug resistance may be uncovered by analyzing the ability of tumor subpopulations to acquire drug resistance after one or several previous exposures to chemotherapeutic drugs, as opposed to examining intrinsic drug resistance only. Furthermore, ability to detect induced or acquired drug resistance in vitro may be strongly influenced by the types of assay used to detect and monitor drug resistanc. In particular, three-dimensional cell culture systems may reveal acquired or induced “multicellular” drug resistance in situations where conventional two-dimensional culture systems may therefore reveal as yet undiscovered associations between the phenotypes of metastasis and drug resistance.     

Studies on low-level MDR cells

Acquired or spontaneous resistance is a major clinical problem in the treatment of cancer. Low levels of MDR gene expression or P-glycoprotein have been correlated with a high level of drug resistance in vitro and a poor response to chemotherapy in some tumors. A strong correlation between MDR mRNA, P-glycoprotein levels and degree of drug resistance has not been found in several resistant model tumor cell lines. In some cell lines at low and high level of resistance different mechanisms seem to be involved.     

基于最小累积阻力模型的崩岗侵蚀危险性分区——以安溪县小流域为例

为在风险评价中体现出崩岗侵蚀产生的可能性和空间趋势、分清崩岗防治中的主次区域,本研究以安溪县小流域为研究区,以崩岗为源地,通过最小累积阻力模型构建崩岗扩张阻力面并划分危险性分区。结果表明: 研究区内崩岗周围区域阻力值较低,西北部及东南部阻力值较高,崩岗扩张阻力面形态为岛屿型。依据阻力面将研究区域分为高危险区、较高危险区、中等危险区、较低危险区和低危险区,并由此提出相应的崩岗治理建议。基于阻力面形态提取出鞍部战略点共21个,较低安全区中战略点应作为预防崩岗重点区域。将基于最小累积阻力模型和信息量法的危险性结果进行比较,两者在空间分布态势上一致,证明通过最小累积阻力模型进行危险性分区的结果可靠。     

Cytokeratin-19 associated with apoptosis and chemosensitivity in human cervical cancer cells

Cytokeratins are one group of intermediate filament proteins responsible for the integrity of cell structure, and have been recently reported to play a role in conferring a drug resistance phenotype. MAb Cx-99 is a monoclonal antibody exhibiting the specificity toward its corresponding antigen which was recently identified as the cytokeratin-19 protein. In the present study, we found that the level of cytokeratin-19 in cervical cancer cells could be decreased by incubation of cancer cells with MAb Cx-99. The reduction of cytokeratin-19 level had a killing effect on cervical carcinoma SIHA and HeLa S3 cell lines. The DNA ladder pattern, convoluted nuclei and blebbing morphology were observed with these cells after exposure to MAb Cx-99 for 72 h, suggesting that the cytotoxic mechanism of reduced cytokeratin-19 was mediated by induction of apoptosis. Moreover, the MAb Cx-99 treatment could increase the cytotoxicities of cancer chemotherapeutic agents such as cisplatin and vinblastine to both cervical carcinoma cell lines. The LD80 values were at least 15-fold reduced when cancer cells were treated with cisplatin or vinblastine in the presence of MAb Cx-99. These results suggest that the functional role of cytokeratin-19 was associated with the apoptosis prevention and drug resistance of cervical cancer cells.     

Mechanisms and relevant genes of drug resistance in gastric cancer

Gastric cancer (GC) is one of the most common malignancies in China, and chemotherapy is an important treatment for GC. However, drug resistance remains the main barrier to successful chemotherapy. Drug resistance is a complex phenomenon resulting from a combination of factors and mechanisms. The number of known relevant genes implicated in this phenomenon is growing rapidly. This review focuses on the mechanisms involved in the occurrence of drug resistance and explores the functions of several relevant genes in GC chemotherapy resistance.     

The c‐MYC‐ABCB5 axis plays a pivotal role in 5‐fluorouracil resistance in human colon cancer cells

c‐MYC overexpression is frequently observed in various cancers including colon cancer and regulates many biological activities such as aberrant cell proliferation, apoptosis, genomic instability, immortalization and drug resistance. However, the mechanism by which c‐MYC confers drug resistance remains to be fully elucidated. In this study, we found that the c‐MYC expression level in primary colorectal cancer tissues correlated with the recurrence rate following 5‐fluorouracil (5‐FU)‐based adjuvant chemotherapy. Supporting this finding, overexpression of exogenous c‐MYC increased the survival rate following 5‐FU treatment in human colon cancer cells, and knockdown of endogenous c‐MYC decreased it. Furthermore, c‐MYC knockdown decreased the expression level of ABCB5, which is involved in 5‐FU resistance. Using a chromatin immunoprecipitation assay, we found that c‐MYC bound to the ABCB5 promoter region. c‐MYC inhibitor (10058‐F4) treatment inhibited c‐MYC binding to the ABCB5 promoter, leading to a decrease in ABCB5 expression level. ABCB5 knockdown decreased the survival rate following 5‐FU treatment as expected, and the ABCB5 expression level was increased in 5‐FU‐resistant human colon cancer cells. Finally, using a human colon cancer xenograft murine model, we found that the combined 5‐FU and 10058‐F4 treatment significantly decreased tumorigenicity in nude mice compared with 5‐FU or 10058‐F4 treatment alone. 10058‐F4 treatment decreased the ABCB5 expression level in the presence or absence of 5‐FU. In contrast, 5‐FU treatment alone increased the ABCB5 expression level. Taken together, these results suggest that c‐MYC confers resistance to 5‐FU through regulating ABCB5 expression in human colon cancer cells.     

产AmpC酶阴沟肠杆菌的基因分析及其耐药性

探讨昆明地区阴沟肠杆菌的耐药性及与结构基因ampC和调节基因ampD的相关性。通过K-B法检测阴沟肠杆菌的药敏情况,头孢西丁三维试验检测AmpC酶,PCR法扩增ampC和ampD基因。结果显示74株阴沟肠杆菌经头孢西丁三维试验检测,产AmpC酶的有17株,检出率为22.3%,而且产酶菌株抗生素敏感率低于非产酶菌株。ampC基因扩增阳性率为89.2%(66/74);64株ampD基因阳性率为86.5%(64/74)。实验证实昆明地区产酶阴沟肠杆菌耐药状况严重,与结构基因ampC和调节基因ampD密切相关。     

Role of fatty acid synthase in gemcitabine and radiation resistance of pancreatic cancers

Human fatty acid synthase (FASN) is a homo-dimeric protein with multi-enzymatic activity responsible for the synthesis of palmitate. FASN expression has been found to be up-regulated in multiple types of human cancers and its expression correlates with poor prognosis possibly by causing treatment resistance. In this study, we tested if FASN expression is up-regulated in human pancreatic cancers and if its higher expression level in pancreatic cancers causes intrinsic resistance to gemcitabine and radiation. We found that FASN expression is significantly up-regulated in human pancreatic cancer tissues without any correlation to age, sex, race, and tumor stage. Knocking down or over-expressing FASN significantly down- or up-regulate resistance of pancreatic cancer cell lines to both gemcitabine and radiation treatments. These findings imply that the elevated FASN expression in pancreatic cancers may contribute to unsuccessful treatments of pancreatic cancers by causing intrinsic resistance to both chemotherapy and radiation therapy.     

Three-dimensional culture models to study drug resistance in breast cancer

Despite recent advances in breast cancer treatment, drug resistance frequently presents as a challenge, contributing to a higher risk of relapse and decreased overall survival rate. It is now generally recognized that the extracellular matrix and cellular heterogeneity of the tumor microenvironment influences the cancer cells' ultimate fate. Therefore, strategies employed to examine mechanisms of drug resistance must take microenvironmental influences, as well as genetic mutations, into account. This review discusses three-dimensional (3D) in vitro model systems which incorporate microenvironmental influences to study mechanisms of drug resistance in breast cancer. These bioengineered models include spheroid-based models, biomaterial-based models such as polymeric scaffolds and hydrogels, and microfluidic chip-based models. The advantages of these model systems over traditionally studied two-dimensional tissue culture polystyrene are examined. Additionally, the applicability of such 3D models for studying the impact of tumor microenvironment signals on drug response and/or resistance is discussed. Finally, the potential of such models for use in the development of strategies to combat drug resistance and determine the most promising treatment regimen is explored.