P-glycoprotein expression induced by glucose depletion enhanced the chemosensitivity in human hepatocellular carcinoma cell-lines

Chemoresistance in cancer cells is frequently associated with an over-expression of the P-glycoprotein (P-gp). The expression of P-gp can be regulated as the cells encounter a number of chemical, physical or environmental stimuli. In this study, P-gp was found gradually expressed in a human hepatocellular carcinoma (HCC) QGY-7703 cells after 48 h of culturing in glucose-free medium. This phenomenon disappeared after the removal of glucose deprivation culture conditions. Mdr1-cDNA isolated from the cell line cultured in glucose-free conditions (namely QGY-7703G), was transiently transformed into the parent QGY-7703 cells, and multi-drug resistance was eventually induced. Results from XTT cytotoxicity assays indicated that the mdr1 gene was functional and the P-gp could restore the QGY-7703 cell's ability to withstand high concentrations of a number of chemotherapeutic agents. A P-gp inhibitor, verapamil, could completely reverse the cellular drug resistance when applied to the QGY-7703G cells. Our results indicated that an alteration of a specific state in cells caused by an external stimulus in vitro may lead to an expression of stress proteins (e.g. P-gp), which may enhance the cells' survival in adverse conditions. The expressed P-gp induced by glucose deprivation has a functional role in affecting the chemosensitivity in HCC QGY-7703G cells. Inhibition of P-gp activity may enhance the effect of the cancer cells towards cancer chemotherapy.     

Inhibitory effect of parvovirus H—1 on the formation of colonies of human hepatoma cell line in vitro and its tumors in nude mice

The inhibitory effect of parvovirus H-1 on the colonyforming ability.in vitro of QGY-7703,a cultured human hepatoma cell line,and on the formation and growth of its tumors in nude mice was studied.With higher multiplicity of infection(MOI) of H-1 given,survival of the QGY-7703 cells was found to be decreased.H-1 DNA amplification level at 30h postinfection(p.i.) was detected to be 7.4 times higher than that at 2h by dispersed cells assay,while the cells were delayed to enter into S phase.Plaques were formed in the indicator cells(new-born human kidney cell line,NBK) by progeny H-1 virus particles released from the infected QGY-7703 cells by infectious cell center assay.The formation of tumors in nude mice by QGY-7703 cells which were injected s c at 2h postinfection was observed to by prevented in 2 proups with given MOI 25 and 50.The tumor growth of MOI 10 group occurred at a lower exponential rate than that of control,after a 20d latent period.It was evident that parvovirus H-1 exhibited a direct inhibitory effect on the formation and growth of human hepatoma cells in vivo as well as in vitro.     

MKi67-siRNA可抑制QGY-7703细胞的生长

为了探讨MKI67在肝癌细胞发生发展中的作用,采用实时定量 PCR 方法检测人肝细胞癌 QGY 7703 细胞中MKI67 基因表达水平, 以及 MKI67在肝细胞癌组织和癌旁正常组织中的表达情况,设计并合成针对MKI67 的siRNA,利用脂质体转染法将其转入QGY-7703 细胞内,通过MTT和细胞集落形成实验观察MKI67-siRNA 对QGY-7703细胞生长活性和增殖能力的影响.实时定量PCR结果表明,MKI67在肝细胞癌组织中的表达水平明显高于癌旁正常组织（P< 0.01）. MTT和细胞集落形成实验结果显示,转染MKI67-siRNA 的QGY-7703细胞生长活性和集落形成率明显低于对照组（P< 0.01）.由此得出结论：MKI67 在肝癌细胞系QGY-7703细胞中的表达水平较高,且它在肝癌组织中的表达水平明显上调. 同时,MKI67-siRNA 可以有效抑制QGY-7703细胞的生长活性和增殖能力,提示MKI67可能与肝细胞癌的发生、发展相关.     

Proteomic investigation of taxol and taxotere resistance and invasiveness in a squamous lung carcinoma cell line

Pulse selections on a chemotherapy naive squamous lung carcinoma cell line, SKMES-1, with clinically relevant concentrations of taxanes (taxol or taxotere) resulted in the development of a stable taxotere-resistant variant, SKMES-1-Taxotere and an unstable taxol-resistant variant, SKMES-1-Taxol. Both variants exhibited increased invasiveness in vitro. The unstable nature of SKMES-1-Taxol facilitated looking at factors involved in loss of taxol resistance and increased invasion. The taxotere and taxol-resistant cell lines were 5.9-fold and 12.5-fold resistant to taxotere and taxol respectively. Alterations in expression of/or point mutations in tubulin, the main target of taxanes, is a major mechanism or resistance. However, alterations in expression of beta tubulin were not consistent in the taxane-selected variants. Cross-resistance to adriamycin, vincristine and etoposide (VP-16) was consistent with overexpression of P-glycoprotein (P-gp). However, P-gp alone is not sufficient to confer the complete multiple drug resistance phenotype as all cell lines exhibited cross-resistance to 5-Fluorouracil (5-FU) and more than one mechanism has been linked to taxane resistance. There was no correlation between the fall of taxol resistance in SKMES-1-Taxol and P-gp expression indicating the loss in resistance to be independent of P-gp expression. Furthermore, resistance to the other drugs was not unstable in SKMES-1-Taxol suggesting some parallel mechanisms of resistance. Two-dimensional electrophoresis coupled with matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry was used to identify alterations in expression of specific proteins associated with taxane resistance. A large number of differentially regulated proteins were identified in the resistant and invasive variants affecting cellular processes including stress response, protein turnover and cytoskeleton proteins.     

AFP的亚细胞定位及对肿瘤细胞生长的影响

目的观察甲胎蛋白（AFP）在不同肿瘤细胞中的亚细胞定位及对肿瘤细胞生长的影响。方法运用免疫荧光的方法观察内源性AFP在HeI。a细胞、QGY-7703细胞、MCF-7细胞中的亚细胞定位。将构建的表达AFP的质粒pcDNA3-AFP及AFP腺病毒siRNA干涉载体Adv—AFPsiRNA作用于QGY-7703细胞,MCF-7细胞,运用M1Tr,集落形成实验检测细胞增殖状况。结果免疫荧光显示,内源性的AFP在HeLa细胞、QGY-7703细胞、MCF-7细胞均只在细胞质中表达。pcDNA3-AFP使QGY-7703的细胞活性增加了2l％（P〈0．05）及集落形成能力增加了32％（P〈0．01）,MCF-7实验组比对照组细胞活性降低了30％（P〈0．01）．克隆形成能力降低82％（P〈0．01）。Adv—AFPsiRNA使QGY-7703的细胞活性降低了22％（P〈0．05）,平均克隆形成能力降低52％（P〈0．01）,MCF-7细胞活性提高了24．5％（P〈0．05）,克隆形成能力提高了89％（P〈O．01）。结论内源性的AFP只在细胞质中表达。AFP能促进QGY-7703细胞的增殖及克隆形成能力,而在MCF-7细胞中发挥相反的作用。腺病毒介导的内源性的AFP表达的下调能降低QGY-7703的增殖,却增加了MCF-7的细胞活性及克隆形成能力。     

Some differentiating effects of selenium on the cultured human hepatoma cells and human pulmonary adenocarcinoma cells in vitro

Two human hepatoma cell lines, QGY-7703 and SMMC-7721, and two human pulmonary adenocarcinoma cell lines, LTEP-a-2 and SPC-A-1, were found to respond to 1 μg/mL Na₂SeO₃, 24 h, in-vitro treatment by decreasing its confluent saturation density. The same treatment was found to cause an increase in the adhesiveness of cells measured as resistance to detachment by trypsin/EDTA. The pathological features of tumors after heterotransplantation of treated and untreated cells were similar, but the size of tumor grown from treated cells was much smaller.     

MicroRNA-142-3p, a new regulator of RAC1, suppresses the migration and invasion of hepatocellular carcinoma cells

RAC1 regulates a diverse array of cellular events including migration and invasion. MicroRNAs (miRNAs) have a key role in the regulation of gene expression. In this study, we demonstrated that microRNA-142-3p (miR-142-3p) acted as a negative regulator of human RAC1. Overexpression of miR-142-3p decreased RAC1 mRNA and protein levels. Moreover, the overexpression of miR-142-3p suppressed, while blocking of miR-142-3p increased colony formation, migration and invasion in hepatocellular carcinoma (HCC) cell lines (QGY-7703 and SMMC-7721). RAC1 overexpression without the 3'untranslated region abolished the effect of miR-142-3p in the QGY-7703 and SMMC-7721 cells. These results demonstrated that miR-142-3p directly and negatively regulates RAC1 in HCC cells, which highlights the importance of miRNAs in tumorigenesis.     

人肝癌细胞p53基因的表达及其对细小病毒H-1的敏感性

本文利用单链构象多态性分析,17号染色体短臂等位基因杂合性分析,Northern印迹,免疫沉淀,p53基因第7外显子酶切等技术检测了两个中国人肝癌细胞系SMMC-7721,YY-8103和一个自发转化的人肝细胞系L-02的p53基因结构与表达。实验表明,这三个细胞系中没有出现17号染色体短臂等位基因杂合性缺失,第4—9外显子也没发生突变,但其mRNA和蛋白表达水平很低。利用MTT比色分析法研究了这三个细胞系和其他已知p53基因背景的八个人肝癌细胞系(QGY-7703、PLC/PRF/5、Huh-7、Hep3B、FOCUS、Tong/ HCC、SK-Hep-1、HepG2)对自主性细小病毒H-1的敏感性。除HepG2细胞外,其他十个细胞系p53基因的结构和/或表达都不正常。经H-1感染(moi=20)后,其敏感性均高于HepG2细胞。本研究初步表明了p53基因结构或表达的不正常可能导致人肝癌或转化细胞对H-1的敏感性的提高。     

DNA methylation-regulated miR-193a-3p dictates resistance of hepatocellular carcinoma to 5-fluorouracil via repression of SRSF2 expression

Chemoresistance prevents effective cancer therapy and is rarely predictable prior to treatment, particularly for hepatocellular carcinoma (HCC). Following the chemoresistance profiling of eight HCC cell lines to each of nine chemotherapeutics, two cell lines (QGY-7703 as a sensitive and SMMC-7721 as a resistant cell line to 5-fluorouracil (5-FU) treatment) were systematically studied for mechanistic insights underpinning HCC 5-FU chemoresistance. Genomic profiling at both DNA methylation and microRNA (miR) levels and subsequent mechanistic studies illustrate a new mechanism for how DNA methylation-regulated miR-193a-3p dictates the 5-FU resistance of HCC cells via repression of serine/arginine-rich splicing factor 2 (SRSF2) expression. In turn, SRSF2 preferentially up-regulates the proapoptotic splicing form of caspase 2 (CASP2L) and sensitizes HCC cells to 5-FU. Forced changes of miR-193a-3p level reverse all of the phenotypic features examined, including cell proliferation, cell cycle progression, and 5-FU sensitivity, in cell culture and in nude mice. Importantly, the siRNA-mediated repression of SRSF2 phenocopies all of the miR-193a-3p mimic-triggered changes in QGY-7703. This newly identified miR-193a-3p-SRSF2 axis highlights a new set of companion diagnostics required for optimal 5-FU therapy of HCC, which involve assaying both the DNA methylation state of the miR-193a gene and the expression of miR-193a-3p and SRSF2 and the relative level of the proapoptotic versus antiapoptotic splicing forms of caspase 2 in clinical samples.