shRNA沉默增殖诱导配体基因抑制胰腺癌细胞生长的研究

目的 研究靶向增殖诱导配体(a proliferation-inducing ligand,APRIL)基因的短发夹RNA(short hairpin RNA,shRNA)在体内外对胰腺癌细胞生长的影响,探讨其对胰腺癌基因治疗的可行性.方法 将前期构建的LV-shAPRIL感染CFPAC1细胞,MTY法及流式细胞技术分别检测CFPAC1细胞生长和凋亡.用CFPAC1细胞建立裸鼠移植瘤模型,观察瘤内注射LV-shAPRIL对瘤生长的影响.结果 LV-shAPRIL感染CFPAC1细胞96 h后,CFPAC1细胞的生长明显受抑制,与对照组及空载体组相比有显著差异(P＜0.05);同时细胞凋亡率为(17.35±0.96)%,明显高于对照组和空载体组(P＜0.05).将LV-shAPRIL局部注射到裸鼠移植瘤内,LV-shAPRIL组肿瘤生长明显比同期对照组和空载体组减缓;第27天LV-shAPRIL组肿瘤体积和重量分别为(821.8±123.3)mm3和(2.16±0.18)g,明显小于其他两组(P＜0.05).结论 靶向APRIL基因的慢病毒表达载体LV-shAPRIL在体内外抑制胰腺癌CFPAC1细胞的生长,为胰腺癌基因治疗探索新的思路.     

Novel gene therapy approaches to pancreatic cancer

One of the most lethal human malignancies, pancreatic adenocarcinoma has remained a therapeutic challenge. Historically, the only curable treatment modalities available to patients with this disease have included pancreaticoduodenectomy with adjuvant chemoradiation. Few patients, however, have resectable disease at the time of presentation, and even for those who are offered this radical course of treatment, post-surgical survival is dismally short. Recently, however, advances in the understanding of the molecular biology of pancreatic cancer have enabled researchers to investigate novel gene therapy approaches to the treatment of this disease. In this paper, we review the common genetic mutations found in pancreatic adenocarcinomas, discuss strategies for the manipulation of genetic targets, and assess current progress in the field of gene therapy as it relates to pancreatic cancer.     

Update on familial pancreatic cancer

Approximately 5% to 10% of patients with pancreatic cancer have one or more first-degree relatives with this disease. A subset of these individuals have a hereditary form of pancreatic cancer designated by association with such hereditary disorders as familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, hereditary pancreatitis, or familial atypical multiple mole melanoma (FAMMM) syndrome. A subset of those FAMMM kindred with the CDKN2A (p16) germline mutation that expresses both pancreatic cancer and malignant melaonoma may constitute a new hereditary pancreatic cancer-prone syndrome.     

New targeted therapies in pancreatic cancer

Patients with pancreatic cancer have a poor prognosis with a median survival of 4-6 mo and a 5-year survival of less than 5%. Despite therapy with gemcitabine, patient survival does not exceed 6 mo, likely due to natural resistance to gemcitabine. Therefore, it is hoped that more favorable results can be obtained by using guided immunotherapy against molecular targets. This review summarizes the new leading targeted therapies in pancreatic cancers, focusing on passive and specific immunotherapies. Passive immunotherapy may have a role for treatment in combination with radiochemotherapy, which otherwise destroys the immune system along with tumor cells. It includes mainly therapies targeting against kinases, including epidermal growth factor receptor, Ras/Raf/mitogenactivated protein kinase cascade, human epidermal growth factor receptor 2, insulin growth factor-1 receptor, phosphoinositide 3-kinase/Akt/m TOR and hepatocyte growth factor receptor. Therapies against DNA repair genes, histone deacetylases, micro RNA, and pancreatic tumor tissue stromal elements(stromal extracellular matric and stromal pathways) are also discussed. Specific immunotherapies, such as vaccines(whole cell recombinant, peptide, and dendritic cell vaccines), adoptive cell therapy and immunotherapy targeting tumor stem cells, have the role of activating antitumor immune responses. In the future, treatments will likely include personalized medicine, tailored for numerous molecular therapeutic targets of multiple pathogenetic pathways.     

Gene therapy for gastric cancer： Is it promising？

Gastric cancer is one of the most common tumorsworldwide.The therapeutic outcome of conventionaltherapies is inefficient.Thus,new therapeutic strategiesare urgently needed.Gene therapy is a promisingmolecular alternative in the treatment of gastric cancer,including the replacement of defective tumor suppressorgenes,the inactivation of oncogenes,the introduction ofsuicide genes,genetic immunotherapy,anti-angiogeneticgene therapy,and virotherapy.Improved molecularbiological techniques and a better understanding ofgastric carcinogenesis have allowed us to validate avariety of genes as molecular targets for gene therapy.This review provides an update of the new developmentsin cancer gene therapy,new principles,techniques,strategies and vector systems,and shows how they maybe applied in the treatment of gastric cancer.     

Gene therapy for pancreatic cancer

Despite improvements in surgical care and locoregional therapy, the prognosis of patients with pancreatic cancer has seen little improvement over the last several decades. It is difficult to diagnose pancreatic cancer at its earliest stages when it is amenable to cure by surgical resection because it is too small to produce symptoms in the affected patient. Recent improvements in radiographic modalities aimed at earlier detection and extent of cancer spread have enabled the clinician to provide the most efficacious treatment regimen possible. Nevertheless, pancreatic cancer is very aggressive locally and frequently metastasizes to the liver and peritoneum. New strategies are necessary to treat pancreatic cancer and gene therapy offers hope in this regard. Many studies have revealed the promise of gene therapy in the treatment of pancreatic cancer in rodent models. Early clinical trials are ongoing to evaluate the success of these gene therapy regimens in humans. In this article we review the gene therapy strategies currently employed in the fight against pancreatic cancer, including antisense strategies, gene-directed prodrug activation therapy, promoter gene strategies, and oncolytic viral therapy.     

A Review of Kinases Implicated in Pancreatic Cancer

The current 5-year survival rate of pancreatic cancer is about 3% and the median survival less than 6 months because the chemotherapy and radiation therapy presently available provide only marginal benefit. Clearly, pancreatic cancer requires new therapeutic concepts. Recently, the kinase inhibitors imatinib and gefitinib, developed to treat chronic myelogenous leukaemia and breast cancer, respectively, gave very good results. Kinases are deregulated in many diseases, including cancer. Given that phosphorylation controls cell survival signalling, strategies targeting kinases should obviously improve cancer treatment. The purpose of this review is to summarize the present knowledge on kinases potentially usable as therapeutic targets in the treatment of pancreatic cancer. All clinical trials using available kinase inhibitors in monotherapy or in combination with chernotherapeutic drugs failed to improve survival of patients with pancreatic cancer. To detect kinases relevant to this disease, we undertook a systematic screening of the human kinome to define a ‘survival kinase’ catalogue for pancreatic cells. We selected 56 kinases that are potential therapeutic targets in pancreatic cancer. Preclinical studies using combined inhibition of PAK7, MAP3K7 and CK2 survival kinases in vitro and in vivo showed a cumulative effect on apoptosis induction. We also observed that these three kinases are rather specific of pancreatic cancer cells. In conclusion, if kinase inhibitors presently available are unfortunately not efficient for treating pancreatic cancer, recent data suggest that inhibitors of other kinases, involved more specifically in pancreatic cancer development, might, in the future, become interesting therapeutic targets.     

Recent progress in targeting cancer

In recent years, numerous new targets have been identified and new experimental therapeutics have been developed. Importantly, existing non-cancer drugs found novel use in cancer therapy. And even more importantly, new original therapeutic strategies to increase potency, selectivity and decrease detrimental side effects have been evaluated. Here we review some recent advances in targeting cancer.     

Treatment of familial pancreatic cancer and its precursors

Opinion statement Approximately 10% of pancreatic cancers are believed to have a familial basis. The familial aggregation of pancreatic cancers provides a unique opportunity to prevent the development of pancreatic cancer, to identify and treat precancerous lesions of the pancreas, and to advance our understanding of the genetic basis for the development of all forms of pancreatic cancer. After appropriate genetic counseling, individuals with a strong family history of pancreatic cancer can now be tested for inherited genetic alterations that are known to increase the risk of pancreatic cancer. These include germline BRCA2, STK11/LKB1, p16/CDKN2A and PRSS1 gene mutations. Individuals with one of these inherited genetic alterations and individuals with a strong family history of pancreatic cancer can be counseled on smoking cessation and possible dietary modifications. Selected individuals, even if they are asymptomatic, can be screened using a combination of endoscopic ultrasound and multidetector computed tomography. Patients found to have a mass lesion in the pancreas would then be candidates for surgical resection. The resection of noninvasive precancers will cure these lesions before they have the opportunity to spread and metastasize. Even with the best early detection efforts, some patients will still be diagnosed with an invasive cancer. Surgical resection of invasive pancreatic cancer is proven to be safe and can provide long-term survival in patients with small, node-negative, and margin-negative cancers. Chemotherapy and radiation therapy are effective in some patients with invasive pancreatic cancer, but these therapies do not usually result in long-term cures. Individuals with a family history of pancreatic cancer may also choose to join a research study such as the National Familial Pancreas Tumor Registry.     

Can one target T-cell ALL?

Progress in our understanding of the central genes, pathways, and mechanisms in the pathobiology of T-cell acute lymphoblastic leukemia (T-ALL) has identified key drivers of the disease, opening new opportunities for therapy. Drugs targeting highly prevalent genetic alterations in NOTCH1 and CDKN2A are being explored, and multiple other targets with readily available therapeutic agents, and immunotherapies are being investigated. The molecular basis of T-ALL is reviewed here and potential targets and therapeutic targets discussed.     

Gene therapy in pancreatic cancer

Pancreatic cancer(PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC.This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website(http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property.Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras,anti-angiogenesis gene VEGFR, suicide gene HSK-TK,cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiother-apy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.     

蛋白质组学在胰腺癌中的研究进展

胰腺癌是一种常见的恶性肿瘤,迫切需要早期诊断及治疗。快速发展的蛋白质组学技术为探讨胰腺癌发生的分子机制、发现新的肿瘤标记物及治疗靶点提供了新的手段,在胰腺癌研究中显示出巨大的前景。     

MLPA技术在检测胰腺癌细胞系9p21大片段缺失中的应用

目的:评价MLPA技术检测染色体9p21区大片段缺失的有效性及判断缺失边界的准确性,并探讨染色体9p21区大片段缺失的意义.方法:利用MLPA技术检测胰腺癌细胞系PANC-1和BxPC3的9p21区缺失情况,并利用常规PCR实验对MLPA缺失边界进行验证.结果:MLPA检测发现PANC-1和BxPC3均存在累及MTAP、CDKN2A和CDKN2B等基因大片段缺失的情况.PCR实验证实MLPA对PANC-1端粒侧的缺失边界判断准确.PANC-1细胞系染色体9p21区大片段缺失的端粒侧缺失断点位于MTAP基因内.结论:MLPA技术是检测染色体9p21大片段缺失的有效方法,能准确判断大片段缺失边界范围,适合于aCGH检测后大样本筛查.PANC-1细胞系中染色体9p21区大片段缺失可能改变MTAP基因结构.     

The MLL fusion gene, MLL-AF4, regulates cyclin-dependent kinase inhibitor CDKN1B (p27kip1) expression

MLL, involved in many chromosomal translocations associated with acute myeloid and lymphoid leukemia, has >50 known partner genes with which it is able to form in-frame fusions. Characterizing important downstream target genes of MLL and of MLL fusion proteins may provide rational therapeutic strategies for the treatment of MLL-associated leukemia. We explored downstream target genes of the most prevalent MLL fusion protein, MLL-AF4. To this end, we developed inducible MLL-AF4 fusion cell lines in different backgrounds. Overexpression of MLL-AF4 does not lead to increased proliferation in either cell line, but rather, cell growth was slowed compared with similar cell lines inducibly expressing truncated MLL. We found that in the MLL-AF4-induced cell lines, the expression of the cyclin-dependent kinase inhibitor gene CDKN1B was dramatically changed at both the RNA and protein (p27kip1) levels. In contrast, the expression levels of CDKN1A (p21) and CDKN2A (p16) were unchanged. To explore whether CDKN1B might be a direct target of MLL and of MLL-AF4, we used chromatin immunoprecipitation (ChIP) assays and luciferase reporter gene assays. MLL-AF4 binds to the CDKN1B promoter in vivo and regulates CDKN1B promoter activity. Further, we confirmed CDKN1B promoter binding by ChIP in MLL-AF4 as well as in MLL-AF9 leukemia cell lines. Our results suggest that CDKN1B is a downstream target of MLL and of MLL-AF4, and that, depending on the background cell type, MLL-AF4 inhibits or activates CDKN1B expression. This finding may have implications in terms of leukemia stem cell resistance to chemotherapy in MLL-AF4 leukemias.     

胰腺癌免疫治疗及其最新进展

胰腺癌是一种预后极差的恶性肿瘤,胰腺导管腺癌(pancreatic ductal adenocarcinoma,PDAC)是其中最常见的类型,患者被诊断时多为晚期。晚期患者在所有患者中所占比例可超过80%,这类人群的治疗主要是全身化疗,但化疗效果有限。大多数针对PDAC新疗法的研究与开发则开始关注新辅助治疗以及对各种间质成分的靶向,并且旨在缓解免疫抑制的药物疗法也备受关注,但不管是PD-1/PD-L1抗体还是CTLA-4抗体,抑或是两类药物的联合,在改善胰腺癌患者的生存方面均未能获得显著的成效。由此,我们猜测,通过对其他潜在免疫疗法的探索与研究,或许可以给胰腺癌的治疗带来新的希望。本综述旨在总结胰腺癌免疫治疗及其最新进展,通过对其进一步的理解来认识此疾病带来的治疗难点,从而有望改善其治疗策略。     

Molecular targeting to treat gastric cancer

Trastuzumab that targets human epidermal growth factor receptor 2 (HER2) protein is the only approved molecular targeting agent for treating gastric cancer in Japan and the outcomes have been favorable. However, trastuzumab is effective for only 10% to 20% of the population with gastric cancer that expresses HER2 protein. Molecular targeting therapy with bevacizumab against vascular endothelial growth factors (VEGF) and with cetuximab and panitumumab against the epidermal growth factors pathway that have been approved for treating colorectal cancer are not considered effective for treating gastric cancer according to several clinical trials. However, ramucirumab that targets VEGF receptor-2 prolonged overall survival in a large phase III clinical trial and it might be an effective molecular targeting therapy for gastric cancer. The significance of molecular targeting therapy for gastric cancer remains controversial. A large-scale randomized clinical trial of novel molecular targeting agents with which to treat gastric cancer is needed.     

Targeting X-linked inhibitor of apoptosis protein inhibits pancreatic cancer cell growth through p-Akt depletion

AIM: To determine whether lentivirus-mediated shRNA targeting the X-linked inhibitor of apoptosis protein (XIAP) gene could be exploited in the treatment of pancreatic cancer.METHODS: Human pancreatic cancer cells Panc-1, Mia-paca2, Bxpc-3 and SW1990, infected with lentivirus, were analyzed by real-time polymerase chain reaction (PCR). Western blotting was used to examine XIAP protein levels, survivin and p-Akt to confirm the result of real-time PCR and determine the possible mechanism. The 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to measure IC₅₀ to determine chemosensitivity to the chemotherapeutic drugs 5-fluorouracil (5-FU) and gemcitabine. A colony assay, MTT assay and a tumorigenicity experiment were used to study cell proliferation in vitro and in vivo. Caspase-3/7 activity, 4'',6-diamidino-2-phenylindole-staining and flow cytometric measurements were used to study apoptosis in SW1990 cells.RESULTS: XIAP proteins were found to be differentially expressed among pancreatic cancer cell lines Panc-1, Mia-paca2, Bxpc-3 and SW1990. Data of real-time PCR and Western blotting showed that XIAP was reduced persistently and markedly by lentivirus-mediated shRNA. Downregulation of XIAP by transfection with XIAP shRNA resulted in decreased p-Akt expression. XIAP shRNA also inhibited the growth of pancreatic cancer cells in vitro and in vivo, enhanced drug-induced apoptosis and increased chemosensitivity to 5-FU and gemcitabine. Results also suggest that inhibition of XIAP and subsequent p-Akt depletion may have an anti-tumor effect through attenuating the ability of cancer cells to survive.CONCLUSION: Lentivirus-mediated gene therapy is an attractive strategy in the treatment of pancreatic cancer and justifies the use of lentivirus in pancreatic cancer gene therapy studies.