癌基因药物载体材料的研究进展

开发基因药物的主要任务之一是寻找易于微粒化、能高效地将外部药物基因转入具体靶向癌细胞内而自身又无毒性的载体。病毒具有极强的将遗传物质转入宿主细胞的能力，但本身却有毒性，必须先改性处理尽可能去除它的毒性，同时又要保持它的高转染能力。考虑病毒载体的危险性，人们将注意力转向非病毒材料作栽体。非病毒材料一般带正电，易于与带负电的DNA结合形成非病毒／DNA复合物。相对病毒栽体，非病毒载体材料的转染能力较差，但其制备工艺简单，基因药物易于微粒化，且安全。介绍了用作癌基因药物病毒载体和非病毒载体的两类材料的结构和载转特性。

Effects of Wei Chang An on expression of multiple genes in human gastric cancer grafted onto nude mice

AIM： To investigate the expression of multiple genes in Chinese jianpi herbal recipe Wei Chang An （WCA） in human gastric cancer cell line SGC-7901. METHODS： A human gastric adenocarcinoma cell line SGC-7902 grafted onto nude mice was used as the animal model. The mice were randomly divided into 3 groups, one control and the two representing experimental conditions. Animals in the two experimental groups received either WCA over a 34-d period or 5-fluorouracil （5-FU） over 6-d period starting at 8th d after grafting. Control animals received saline on an identical schedule. Animals were killed 41 d after being grafted. The expression profiles in paired WCA treated gastric cancer samples and the N.S. control samples were studied by using a cDNA array representing 14181 cDNA clusters. The alterations in gene expression levels were confirmed by Real-time Quantitative polymerase chain reaction （qPCR）. RESULTS： When compared with controls, the average tumor inhibitory rate in WCA group was 44.32% ± 5.67% and 5-FU 47.04% ± 22.33% （P 〈 0.01, respectively）. The average labeling index （LI） for PCNA in WCA group and 5-FU group was significantly decreased compared with the control group. Apoptotic index （AI） was significantly increased to 9.72% ± 4.52% using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling （TUNEL） method in WCA group compared with the controls 2.45% ± 2.37%. 5-FU group was also found to have a significantly increased AI compared with the controls. The expression of cleaved Caspase-3 in WCA group and 5-FU group was significantly increased compared with the control group respectively. There were 45 different expressed sequence tags （ESTs） among the control sample pool and WCA sample pool. There were 24 ESTs up-regulated in WCA samples and 21 ESTs down-regulated. By using qPCR, the expression level of Stat3, rap2 interacting protein x （RIPX）, regulator of differentiation 1 （ROD1） and Bcl-2 was lower in WCA group than that in control group respectively. By using SP immunohistochemical method the expression of Phospho-Stat3 （Tyr705） and Bcl-2 in WCA group and 5-FU group was significantly decreased compared with the control group respectively. CONCLUSION： WCA could inhibit gastric cancer cell SGC-7901 growth in vivo. WCA could induce gastric cancer cell apoptosis and suppress proliferation. Its mechanisms might be involved in the down-regulation of Star3, RIPX, ROD1 and Bcl-2 gene.

Two novel germline mutations of MLH1 and investigation of their pathobiology in hereditary non-polyposis colorectal cancer families in China

AIM： To detect germline mutations of MLH1, and investigate microsatellite instability and expression of MLH1 in tumor tissues of hereditary non-polyposis colorectal cancer （HNPCC） with two novel germline mutations, and further investigate the pathobiology of the two novel mutations of MLH1. METHODS： RNA was extracted from the peripheral blood of 12 patients from 12 different families that fulfilled the Amsterdam 11 Criteria for HNPCC. Germline mutations of MLH1 were determined by RT-PCR, followed by cDNA sequencing analysis. PCR-GeneScan analysis was used to investigate microsatellite instability with a panel of five microsatellite markers （BAT26, BAT25, D5S346, D2S123 and mfd15）, along with immunohistochemical staining to detect the expression of MLH1 protein in two patients＇ tumor tissues with novel mutations. RESULTS： Three germline mutations were found in four patients, one of the mutations has previously been reported, but the other two, CGC→TGC at codon 217 of exon 8 and CCG→CTG at codon 581 of exon 16, have not been reported. The two patients＇ tumor tissues with novel mutations had high-frequency microsatellite instability that showed more than two unstable loci, and both tumors lost their MLH1 protein expression. CONCLUSION： The two novel germline mutations of MLH1 in HNPCC families i.e. CGC→TGC at codon 217 of exon 8 and CCG→CTG at codon 581 of exon 16, are very likely to have pathological significance.

HER2 over-expression and response to different chemotherapy regimens in breast cancer

Purpose: To exam the relationship between HER2 over-expression and different adjuvant chemotherapies in breast cancer. Patients and Methods: A total of 1625 primary breast cancer patients who received post-surgery adjuvant chemotherapy in Tianjin Cancer Hospital,China,from July 2002 to November 2005 were included in the study. Among them,600 patients were given CMF (CTX+MTX+5-Fu) regimen,600 given CEF (CTX+E-ADM+5-Fu) regimen,and 425 given anthracyclines plus taxanes regimen,with mean follow-up time of 42 months. Results: In CMF treatment group,the 3-year disease free survival (DFS) in HER2 over-expressed patients was lower than that of the HER2-negative ones (89.80% vs 91.24%,P=0.0348); in node-positive subgroup,the 3-year DFS was 84.72% in HER2 over-expressed patients,and 90.18% in the HER-2-negative ones (P=0.0271). Compared to CMF regimen,anthracyclines and anthracyclines plus taxanes regimens are more effective (P<0.05) in node-positive HER2 over-expression than those in the node-negative. Conclusion: HER2 over-expression is an independent index for predicting poor prognosis and short DFS for breast cancer patients. HER2 over-expressed patients are resistant to CMF regimen chemo-therapy,but sensitive to anthracyclines-based or anthracyclines plus taxanes regimen. HER2 expression can be taken as a marker for therapies in breast cancer.

Identification of eight genes that are potentially involved in tamoxifen sensitivity in breast cancer cells

Although the antiestrogen agent tamoxifen has long been used to treat women with hormone receptor positive inva-sive breast carcinoma, the mechanisms of its action and acquired resistance to tamoxifen during treatment are largelyunknown. A number of studies have revealed that over-activation of some signaling pathways can cause tamoxifenresistance; however, very little information is available regarding the genes whose loss-of-function alternation contrib-ute to tamoxifen resistance. Here we used a forward genetic approach in vitro to generate tamoxifen resistant cells fromthe tamoxifen sensitive breast cancer cell line ZR-75-1, and further identified the disrupted gene in different tamoxifenresistant clones. Retinol binding protein 7, DNA polymerase-transactivated protein 3, γ-glutamyltransferase-like activity 1,slit-robo RhoGTPase-activating protein, tetraspan NET-4, HSPC194, amiloride-sensitive epithelial sodium channel gene,and Notch2, were the eight mutated genes identified in different tamoxifen resistant clones, suggesting their requirementfor tamoxifen sensitivity in ZR-75-1 cells. Since the functions of these genes are not related to each other, it suggeststhat multiple pathways can influence tamoxifen sensitivity in breast cancer cells.

Targeting late SV40 factor: Is the achilles heel of hepatocarcinogenesis revealed?

Hepatocellular carcinoma (HCC) is a dreadful cancer and a major cause of death among patients with chronic liver disease and cirrhosis. The apparent alterations in a diversity of intracellular pathways found in HCC has set the rational for developing molecular-directed drugs that simultaneously inhibit multiple pathways, such as the multi-kinase inhibitor Sorafenib. However, recently this concept has been challenged by showing that HCC is heavily dependent on a single oncogene designated late SV-40 factor (LSF), a transcription factor that is over-expressed in liver cancer cells and that its expression is strongly correlated with tumor grade and aggressiveness. Furthermore, using an intensive screening for drugs that inhibit LSF activity, Grant et al have found a molecule designated factor quinolinone inhibitor 1 that can specifically block the ability of LSF to bind its target promoters, resulting in a massive death of HCC cells both in vitro and in vivo. The innovative findings of HCC representing "oncogene addiction" to LSF and the ability of a single molecule to block the activity of this oncogene resulting in tumor abolishment are encouraging and provide us with the hope that the "Achilles heel" of HCC has been found.

Demethylation of FANCF gene may be a potential treatment through inhibiting the proliferation of cervical cancer

Objective: The aim of the study was to explore the effect of demethylating agent 5-Aza-2'-deoxycytidine (5-ADC) on expression of Fanconi anemia complementation group F (FANCF) gene and the proliferation of cervical cancer cells, to observe cell's sensitivity to chemotherapeutic drug taxol, and to explore the antitumor effect of 5-ADC as well as the new treatment of cervical cancer. Methods: Cervical cancer cell lines SiHa (FANCF gene full-methylated) and Hela (unmethylated) were treated with 5-ADC. We used the methylation-specific PCR (MSP), reverse transcription-polymerase chain reaction (RT-PCR) and Western blot to detect the FANCF methylation, mRNA and protein respectively. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect the proliferation of cells. The cytotoxicity of taxol was measured by flow cytometer. The nude mice bearing SiHa was used to observe the effect of 5-ADC in vivo. Results: Inhibition of DNA promoter methylation by 5-ADC reactivated the expression of FANCF mRNA and protein in SiHa cells, consistent with decreased growth speed and increased taxol resistance. These results were proven in experiments in vivo. Conclusion: The 5-ADC probably become a potential treatment drug through inhibiting the proliferation of cervical cancer cells in taxol-resistant patients.

MDR1/P-Glycoprotein Overexpression in Bladder Transitional Cell Carcinoma and its Correlation with Expression of Survivin and Fas

OBJECTIVE To explore the expression of the MDR1/P-glycoprotein, Fas and survivin and to examine their correlation with the biologic behavior of bladder transitional cell carcinoma (BTCC). METHODS Immunohistochemistry was used to examine the expression of P-gp, survivin and Fas in BTCC (n=64) and normal bladder mucosa (n=12). RESULTS The expression level of P-gp and survivin in BTCC was higher compared to normal bladder mucosa (P<0.01) and their expression was strongly correlated with clinical grading (P<0.01). In BTCC and normal bladder mucosa Fas expression was 50% and 100%, respectively (P< 0.01). Recurrent BTCC showed higher expression than primary BTCC (P< 0.01) and the expression of P-gp in BTCC had a reverse correlation with Fas expression but no correlation with survivin expression. CONCLUSUON The MDR of BTCC was strongly correlated with the ex- pression of P-gp and Fas, but was not correlated with survivin expres- sion. Thus, enhancing cancer sensitivity to chemotherapy by reversing multidrug resistance with reversal agents or up-regulating Fas expres- sion by apoptotic enhancing agents, might be a potential therapy to pre- vent tumor recurrence and invasiveness.

Induction of apoptosis and change of bcl-2 expression in macrophage Ana-1 cells by all-trans retinoic acid

Macrophage cells play an important role in the initiation and regulation of the immune response. All-trans retinoic acid (ATRA) and its natural and synthetic analogs (retinoids) affect a large number of biological processes.Recently , retinoids have been shown promise in the therapy and prevention of various cancers. However, many interesting questions related to the activities of retinoids remain to be answered: (Ⅰ) Molecular mechanisms by which retinoids exert their effects; (Ⅱ) why the clinical uses of retinoids give undesirable side effects of varying severity with a higher freqllency of blood system symptoms; (Ⅲ)little is known for its impacts on macrophage cells etc. We set up this experiment, therefore, to examine the apoptosis of ATRA on macrophage Ana-1 cell line. Apoptosis of the cells was quantitated, after staining cells with propidium iodide (PI), by both accounting nuclear condensation and flow cytometry. When the cells were treated with ATRA at or higher than 1 μM for more than 24 h, significant amount of the apoptotic cells was observed. Induction of apoptosis of Ana-1 cells by ATRA was in time- and dose-dependent manners, exhibiting the similar pattern as the apoptosis induced by actinomycin D (ACTD). ATRA treatment of Ana-1 cells also caused the changes of the mRNA levels of apoptosis-associated gene bcl-2, as detected by Northern blot analysis. The temporal changes of bcl-2 expression by ATRA was also parallel to that by ACTD. In conclusion,ATRA can induce apoptosis in macrophage cells, which may be helpful in understanding of immunological functions retinoids.

A preliminary study on K-ras,EGFR,and B-raf mutations of esophageal squamous cell carcinoma

Objective: Molecular targeted drugs have been widely used in clinical application which has successfully prolonged some patients' life. Meanwhile, molecular targeted drug therapy for esophageal cancer are attracting more and more attention from doctors and experts. However, little study has been done towards the effect of this approach for treating esophageal squamous cell carcinoma. This paper, therefore, intends to explore the possibilities of applying EGFR-TKI inhibitors or anti-EGFR monoclonal antibody in esophageal squamous cell carcinoma by studying the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Methods: Thirty-five cases of resected specimens of diagnosed esophageal squamous cell carcinoma with complete clinical and pathological data from January to April 2009 were collected. Pyrophosphate was used for observing the mutations of EGFR, K-ras and B-raf in the esophageal squamous cell carcinoma tissues. Results: Examinations were undertaken respectively to the codon segment 746-754 of exon 19 in EGFR genes, codon 12 and 13 in K-ras genes as well as condon 600 in B-raf genes. No mutation was found in EGFR and B-raf genes with mutation rate 0% (0/35), all of codon 12 in K-ras genes were wild-type without any mutation, while 2 specimens of codon 13 had mutations with mutation rate of 5.71% (2/35). Conclusion: In treating esophageal squamous cell carcinoma patients, all K-ras genes are expressed as wild type due to low mutation rate; cetuximab is effective due to low mutation rate of B-raf while EGFR-TKI inhibitor will not be effective enough because of low mutation rate of EGFR genes.

mieroRNA-451通过靶向下调c-myc表达对乳腺癌MDA—MB-231细胞侵袭的影响

目的探讨microRNA-451（miR-451）在乳腺癌中的表达及其对乳腺癌细胞MDA-MB-231侵袭能力的影响。 方法收集2014年1月至2014年12月间普通外科行手术切除并经病理检查证实为乳腺浸润性导管癌（IDC）及对应癌旁组织45例，采用实时定量PCR法分别检测miR-451在肿瘤和癌旁组织中的表达，统计分析miR-451表达与患者临床特征间的关系；采用人工合成的miR-451特异性模拟物（miR-451 mimics）转染人乳腺癌MDA-MB-231细胞，采用Transwell侵袭小室试验检测转染miR-451 mimics后MDA-MB-231细胞侵袭能力的变化。通过实时定量PCR、蛋白免疫印记检测转染miR-451 mimics后其下游潜在靶点c-myc及c-myc下游基质金属蛋白酶（MMP）-2、MMP-9表达变化。 结果与对应癌旁组织相比，miR-451在IDC组织中表达水平明显降低（P〈0.05），IDC组织中低水平的miR-451与肿瘤淋巴结转移及高TNM分期有关（P〈0.05）；miR-451 mimics转染MDA-MB-231细胞后可显著抑制乳腺癌细胞的侵袭能力（P〈0.05）；实时定量PCR及蛋白免疫印记结果证实，过表达miR-451后可显著抑制c-myc、MMP-2、MMP-9的表达水平（P〈0.05）。 结论miR-451在IDC组织中表达下调并与患者不良临床病理特征有关，miR-451可能通过下调c-myc/MMP轴的表达来抑制乳腺浸润性导管癌细胞侵袭。

Natural products and their derivatives as G-quadruplex binding ligands

G-quadruplexes comprise a class of secondary structures that are formed in guanine-rich sequences in eukaryotic genomes and play a crucial role in the regulation of many biological events.G-quadruplexes have become targets for anticancer drugs with high selectivity vs.duplex DNA and low cytotoxicity against normal cells.Natural products and their derivatives display polymorphism,structural complexity,and potent activity.It is,therefore,reasonable to seek ligands targeting G-quadruplexes from natural products.Recently,many successful examples have been reported,showing ligands with excellent anticancer activities.In this review,we summarized the development of research on natural products and derivatives that target G-quadruplex structures in an effort to guide future studies.