RNA interference (RNAi) is a post-transcriptional gene silencing process by targeting mRNA for degradation in a sequence-specific manner. This powerful platform has enormous potential in functional genomics and medical research. As a tool to knock out expression of specific genes in a variety of organisms, RNAi was used to investigate gene function in a high throughput fashion. Highly conserved in evolution RNAi appears to have evolved as a cellular defense mechanism in plants and animals to suppress viral infection, transposon jumping and endogenous aberrant genes. Exploiting the natural mechanism, the researchers can shut down disease-causing genes and develop novel therapeutics against infection, tumor and other disease.
Gene Expression Regulation ; Gene Silencing ; Genomics ; RNA Interference ; RNA, Small Interfering ; RNA-Induced Silencing Complex

Humans ; Neoplasms ; genetics ; immunology ; therapy ; RNA Interference ; RNA, Small Interfering ; RNA-Induced Silencing Complex

Genetic Therapy ; Hepatitis B ; therapy ; Hepatitis C ; therapy ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; RNA-Induced Silencing Complex ; genetics

OBJECTIVETo find some effective short interfering RNA's sites targeting HBV surface gene sequence using shRNA expression vectors.

METHODSFour shRNA expression vectors targeting HBV surface gene sequence were constructed based on pAVU6 + 27 vector, and cotransfected into AD293 cells with HBs-EGFP fusion gene plasmid. The changes of HBs-EGFP image were detected by FACS and microscopy. The HBs-EGFP mRNA expression was evaluated by RT-PCR.

RESULTSFour shRNA expression vectors and HBs-EGFP fusion gene plasmid were successfully constructed. pAVU6 + 4sh579 vector inhibited the HBs-EGFP expression by 69.8% in AD293 and suppressed the HBs-EGFP mRNA expression by 74.6%.

CONCLUSIONSThe results showed that the 579 site of HBV surface gene sequence was an effective target and pAVU6 + 4sh579 vector could suppress the HBs-EGFP expression in AD293 cells

Gene Expression Regulation, Viral ; Gene Silencing ; Gene Targeting ; methods ; Hepatitis B Surface Antigens ; genetics ; metabolism ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; RNA-Induced Silencing Complex ; genetics

Animals ; Gene Silencing ; physiology ; Gene Targeting ; Genetic Therapy ; methods ; Genomics ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; therapeutic use ; RNA-Induced Silencing Complex

OBJECTIVETo evaluate the inhibitory effect of small interfering RNA (siRNA) targeting HBV C gene region on hepatitis B virus (HBV) in vivo.

METHODSAn animal model of HBV infection was developed hydrodynamically, and pcDNA3.1-HBV and siRNA were together injected into the tail vein of the BALB/c mice. HBsAg was analyzed by time-resolved immunofluorometric assay, HBV DNA was analyzed by fluorogenic quantitative PCR (FQ-PCR), HBV C-mRNA was detected by semi-quantitative RT-PCR, and viral specific proteins (HBsAg and HBcAg) in the mice livers were assayed using immunohistochemical staining.

RESULTSIn the mice, the siRNA effectively inhibited HBV replication and expression compared with the controls. The inhibitive effect of siRNA on HBV lasted at least 3 days.

CONCLUSIONThese results demonstrate that RNAi can substantially inhibit HBV replication and expression in vivo.

Animals ; Female ; Hepatitis B ; therapy ; Hepatitis B virus ; genetics ; physiology ; Mice ; Mice, Inbred BALB C ; RNA, Small Interfering ; physiology ; RNA-Induced Silencing Complex ; Random Allocation ; Virus Replication ; genetics

Animals ; Antineoplastic Agents ; therapeutic use ; Gene Silencing ; Genetic Therapy ; methods ; Humans ; MicroRNAs ; antagonists & inhibitors ; therapeutic use ; Neoplasms ; genetics ; therapy ; RNA Interference ; physiology ; RNA, Small Interfering ; antagonists & inhibitors ; therapeutic use ; RNA-Induced Silencing Complex ; metabolism

Plant Dicer-like (DCL) and Argonaute (AGO) are the key enzymes involved in anti-virus post-transcriptional gene silencing (AV-PTGS). Here we show that AV-PTGS exhibited nucleotide preference by calculating a relative AV-PTGS efficiency on processing viral RNA substrates. In comparison with genome sequences of dicot-infecting Turnip mosaic virus (TuMV) and monocot-infecting Cocksfoot streak virus (CSV), viral-derived small interfering RNAs (vsiRNAs) displayed positive correlations between AV-PTGS efficiency and G+C content (GC%). Further investigations on nucleotide contents revealed that the vsiRNA populations had G-biases. This finding was further supported by our analyses of previously reported vsiRNA populations in diverse plant-virus associations, and AGO associated Arabidopsis endogenous siRNA populations, indicating that plant AGOs operated with G-preference. We further propose a hypothesis that AV-PTGS imposes selection pressure(s) on the evolution of plant viruses. This hypothesis was supported when potyvirus genomes were analysed for evidence of GC elimination, suggesting that plant virus evolution to have low GC% genomes would have a unique function, which is to reduce the host AV-PTGS attack during infections.
Arabidopsis ; enzymology ; genetics ; virology ; Base Composition ; Dactylis ; enzymology ; genetics ; virology ; Genes, Plant ; Genes, Viral ; Models, Genetic ; Mustard Plant ; enzymology ; genetics ; virology ; Plant Diseases ; genetics ; virology ; Plant Proteins ; metabolism ; Plant Viruses ; genetics ; pathogenicity ; Plants ; enzymology ; genetics ; virology ; Potyvirus ; genetics ; pathogenicity ; RNA Interference ; RNA, Plant ; genetics ; RNA, Small Interfering ; chemistry ; genetics ; metabolism ; RNA, Viral ; chemistry ; genetics ; metabolism ; RNA-Induced Silencing Complex ; metabolism ; Ribonuclease III ; metabolism ; Selection, Genetic ; Substrate Specificity

BACKGROUNDHIWI is a member of PIWI gene family and its expression is found in various tumors, indicating that it may play a pivotal role in tumor development. This study was designated to examine HIWI protein expression profile in several cancer cell lines and its prognostic value for patients with colorectal cancer.

METHODSTotally 270 patients who underwent surgical resection of primary colorectal cancer between January 1999 and December 2002 with a median follow-up time of 33 months were registered in the study. Formalin-fixed and paraffin-embedded specimens from these patients and 236 matched adjacent non-cancerous normal colorectal tissues were collected. Anti-HIWI monoclonal antibodies were generated and used for evaluating HIWI protein expression. χ(2) tests were conducted to determine the association between HIWI expression and the other variables. Survival curves were estimated using the Kaplan-Meier method and compared by the log-rank test. Multivariate analysis was performed by using the Cox regression model.

RESULTSBy generating antibodies specific for HIWI, we examined HIWI protein expression in several cancer cell lines and demonstrated positive expression of HIWI in 69 out of 270 (25.6%) colorectal cancer tissues; 15 of 236 (6.4%) matched adjacent non-cancerous tissues were also positive for HIWI. Patients with positive HIWI expression in adjacent non-cancerous tissue had statistically lower overall survival (OS) and disease free survival (DFS) compared with negative patients (OS: 10.4% vs. 55.5%, P = 0.009; DFS: 10.4% vs. 55.1%, P = 0.015). For early stage group (stages I and II), patients with positive HIWI expression had significantly lower OS and DFS (OS: 57.4% vs. 79.5%, P = 0.014; DFS: 56.7% vs. 80.5%, P = 0.010). In lymph node negative group, patients with positive HIWI expression had statistically lower OS and DFS (OS: 53.0% vs. 73.5%, P = 0.037; DFS: 52.2% vs. 74.6%, P = 0.025). Multivariate analysis revealed that HIWI over-expression was a significant prognostic factor for OS (95%CI: 1.132 - 2.479, P = 0.010).

CONCLUSIONHIWI could be a potential prognostic biomarker for the patients with colorectal cancer, especially for those at early stages or without lymph node metastasis.

Argonaute Proteins ; metabolism ; Blotting, Western ; Cell Line, Tumor ; Colorectal Neoplasms ; metabolism ; pathology ; Enzyme-Linked Immunosorbent Assay ; Humans ; Immunohistochemistry ; Prognosis

OBJECTIVETo study the expressions of Piwil2 protein and mRNA in papillary thyroid carcinoma (PTC) and the relationship between Piwil2 and the invasion and metastasis of PTC.

METHODSImmunohistochemistry and in situ hybridization were used to detect the expression of Piwil2 protein and mRNA in 60 cases of PTC with the matched adjacent non-cancerous epithelium (NCE).

RESULTSThe positive rates of Piwil2 protein expression in PTC and NCE were 88.3% (53/60) and 10.0% (6/60) respectively, with significant difference (χ² = 73.654, P < 0.01). The positive rates of Piwil2 mRNA expression in PTC and NCE were 85.0% (51/60) and 6.7% (4/60) respectively, also with significant difference (χ(2) = 74.148, P < 0.01). Up-regulated expressions of Piwil2 protein and mRNA were related to the invasion and metastasis of PTC (P < 0.05).

CONCLUSIONSPiwil2 may play a role in the invasion and metastasis of PTC.

Adolescent ; Adult ; Aged ; Argonaute Proteins ; Carcinoma ; Carcinoma, Papillary ; Child ; Female ; Humans ; Lymphatic Metastasis ; Male ; Middle Aged ; Proteins ; genetics ; metabolism ; RNA, Messenger ; genetics ; Thyroid Neoplasms ; metabolism ; pathology ; Young Adult