Phyllanthus emblica Linn. fruit extract potentiates the anticancer efficacy of mitomycin C and cisplatin and reduces their genotoxicity to normal cells in vitro.

OBJECTIVE: Fruit of Phyllanthus emblica Linn. (PE) is widely consumed as a functional food and used as a folk medicine due to its remarkable nutritional and pharmacological effects. Mitomycin C (MMC) and cisplatin (cDDP) are the most widely used forms of chemotherapeutic drug, but their clinical use is limited by their genotoxicity to normal cells. We aimed to determine whether PE has potential to reduce the genotoxicity, while improving the anticancer effect, of MMC and cDDP. METHODS: Cell proliferation was evaluated using the trypan blue exclusion assay and colony-forming assay. Genomic instability (GIN) was measured using the cytokinesis-block micronucleus assay. RESULTS: Co-treatment (72 h) with PE at 20-320 µg/ml significantly enhanced the efficacy of MMC (0.05 µg/ml) and cDDP (1 µg/ml) against Colo205 colorectal cancer cells (P<0.05), and at 80-320 µg/ml significantly decreased MMC- and cDDP-induced GIN and multinucleation in normal colonic NCM460 cells (P<0.05). PE significantly decreased the mitotic index (P<0.01), blocked mitotic progression (P<0.05), and promoted apoptosis (P<0.01) in MMC- and cDDP-treated NCM460 cells, suggesting that PE-mediated inhibition of mitosis and induction of apoptosis may limit the division and survival of highly damaged cells. Also, PE was found to inhibit the clonal expansion of MMC- and cDDP-treated NCM460 cells (P<0.05) and decrease the heterogeneity of the surviving clones. CONCLUSIONS: PE potentiates the anticancer efficacy of MMC and cDDP, while preventing their genotoxicity and inhibiting clonal expansions of unstable genomes in normal cells. These data suggest that PE has the potential to reduce the risk of secondary cancers induced by chemotherapeutics.

Four microRNAs promote prostate cell proliferation with regulation of PTEN and its downstream signals in vitro.

BACKGROUND: Phosphatase and tensin homologue (PTEN), as a tumor suppressor, plays vital roles in tumorigenesis and progression of prostate cancer. However, the mechanisms of PTEN regulation still need further investigation. We here report that a combination of four microRNAs (miR-19b, miR-23b, miR-26a and miR-92a) promotes prostate cell proliferation by regulating PTEN and its downstream signals in vitro. METHODOLOGY/PRINCIPAL FINDINGS: We found that the four microRNAs (miRNAs) could effectively suppress PTEN expression by directly interacting with its 3' UTR in prostate epithelial and cancer cells. Under-expression of the four miRNAs by antisense neutralization up-regulates PTEN expression, while overexpression of the four miRNAs accelerates epithelial and prostate cancer cell proliferation. Furthermore, the expression of the four miRNAs could, singly or jointly, alter the expression of the key components in the phosphoinositide 3-kinase (PI3K)/Akt pathway, including PIK3CA, PIK3CD, PIK3R1 and Akt, along with their downstream signal, cyclin D1. CONCLUSIONS: These results suggested that the four miRNAs could promote prostate cancer cell proliferation by co-regulating the expression of PTEN, PI3K/Akt pathway and cyclin D1 in vitro. These findings increase understanding of the molecular mechanisms of prostate carcinogenesis and progression, even provide valuable insights into the diagnosis, prognosis, and rational design of novel therapeutics for prostate cancer.

Role and fate of SP100 protein in response to Rep-dependent nonviral integration system.

Previously, we studied an AAVS1 site-specific non-viral integration system with a Rep-donor plasmid and a plasmid containing adeno-associated virus integration element. Our earlier study focused on the plasmid vector itself, but the cellular response to the system was still unknown. SP100 is a member of the promyelocytic leukemia nuclear bodies. It is involved in many cellular processes such as transcriptional regulation and the cellular intrinsic immune response against viral infection. In this study, we revealed that SP100 inhibited the Rep-dependent nonviral integration. Conversely, transient expression of Rep78 increased the degradation of SP100. This degradation was inhibited by treatment with MG132, an inhibitor of the ubiquitin proteasome. SP100 and Rep78 are both located in the nucleolus, which provides the spatial possibility for their interaction. Rep78 was coimmunoprecipitated with the enhanced green fluorescent protein (EGFP)-SP100 fusion protein but not EGFP, which verified the interaction between Rep78 and SP100. These results have enriched our knowledge about the cellular protein SP100 and Rep-dependent nonviral integration. It may lead to an improvement in the application of Rep-related transgene integration method and in the selection of target cells.

MicroRNA-7 inhibits tumor growth and metastasis by targeting the phosphoinositide 3-kinase/Akt pathway in hepatocellular carcinoma.

UNLABELLED: MicroRNAs (miRNAs) are known to be involved in carcinogenesis and tumor progression in hepatocellular carcinoma (HCC). Recently, microRNA-7 (miR-7) has been proven to play a substantial role in glioblastoma and breast cancer, but its functions in the context of HCC remain unknown. Here, we demonstrate that miR-7 inhibits HCC cell growth and metastasis in vitro and in vivo. We first screened and identified a novel miR-7 target, phosphoinositide 3-kinase catalytic subunit delta (PIK3CD). Overexpression of miR-7 would specifically and markedly down-regulate its expression. miR-7-overexpressing subclones showed significant cell growth inhibition by G(0) /G(1) -phase cell-cycle arrest and significant impairment of cell migration in vitro. To identify the mechanisms, we investigated the phosphoinositide 3-kinase (PI3K)/Akt pathway and found that Akt, mammalian target of rapamycin (mTOR), and p70S6K were down-regulated, whereas 4EBP1 was up-regulated in miR-7-overexpressing subclones. We also identified two novel, putative miR-7 target genes, mTOR and p70S6K, which further suggests that miR-7 may be a key regulator of the PI3K/Akt pathway. In xenograft animal experiments, we found that overexpressed miR-7 effectively repressed tumor growth (3.5-fold decrease in mean tumor volume; n = 5) and abolished extrahepatic migration from liver to lung in a nude mouse model of metastasis (n = 5). The number of visible nodules on the lung surface was reduced by 32-fold. A correlation between miR-7 and PIK3CD expression was also confirmed in clinical samples of HCC. CONCLUSION: These findings indicate that miR-7 functions as a tumor suppressor and plays a substantial role in inhibiting the tumorigenesis and reversing the metastasis of HCC through the PI3K/Akt/mTOR-signaling pathway in vitro and in vivo. By targeting PIK3CD, mTOR, and p70S6K, miR-7 efficiently regulates the PI3K/Akt pathway. Given these results, miR-7 may be a potential therapeutic or diagnostic/prognostic target for treating HCC.

Development of chimeric gene regulators for cancer-specific gene therapy with both transcriptional and translational targeting.

Cancer gene therapy has been of great challenge in achieving maximal high levels of specificity and more rational efficiency in target cancer cell. We herein developed a novel approach for cancer-specific gene therapy using both transcriptional and translational targeting regulation. We integrated the tumor-specific gene promoter of hTERT, the 5'UTR of bFGF-2, the enhancer of woodchuck hepatitis virus post-transcriptional regulatory element (WRE), and/or the 3'UTR of the human EGFR into two major chimeric gene regulators. We found that chimeric gene regulator I (hTERT_5'UTR...WRE_BGHpolyA) enhanced the specificity of expression in hepatocellular carcinoma (HCC) cells up to 300% in total due to increases at both the transcriptional and translational levels but only 120-200% enhancement at the transcriptional level and 120-180% enhancement at the translational level. In addition, chimeric gene regulator II (hTERT_5'UTR...WRE_3'UTR_BGHpolyA) improved the specificity to 550% and also highly strengthened the stability of the mRNA. In vitro cytotoxicity assays demonstrated that HCC cell growth was inhibited by HSV-1 TK expression under the control of both chimeric regulators, with a relative cell viability of approximately 80% for 2 days and approximately 85% for 4 days after transfection, respectively. These observations represent a new approach for highly tumor-specific gene expression and also provide insights into application to cancer gene therapy.

Functional differentiation between Rep-mediated site-specific integration and transcriptional repression of the adeno-associated viral p5 promoter.

The adeno-associated virus (AAV) p5 promoter controls expression of Rep68 and Rep78, which are responsible for specific integration of the viral genome into the AAVS1 site of the human genome. The p5 promoter contains a Rep-binding element (RBE) sequence that acts as a substrate of the Rep proteins for both site-specific integration of p5 itself and transcriptional suppression of the p5 promoter. To differentiate these two Rep-mediated functions, we dissected the p5 core structure TATA/RBE/YY1+1 through a series of mutations. Mutations in the TATA box or YY1+1 region of p5IEE significantly reduced Rep-mediated site-specific integration (RMSSI) and p5 promoter transcriptional activity, but only the TATA box is involved in Rep-mediated transcriptional suppression (RMTS). Point mutations at nucleotides 266, 267, 268, 270, and 273 of the GAGTGAGC motif in p5 RBE significantly reduced RMSSI efficiency. However, only p5G270T lost the affinity of Rep binding and had significant reduction of RMTS. It appears that RMTS is determined by the affinity of p5RBE for Rep whereas RMSSI requires more stringent conditions. Thus, RMTS and RMSSI can be differentiated by point mutations in the p5 promoter, which is useful in gene therapy in a helper vector to drive Rep expression, as the mutant promoters seldom integrate themselves but remain the RMTS feature for reduced cytotoxicity caused by a high level of Rep protein.

PhiC31 integrase interacts with TTRAP and inhibits NFkappaB activation.

Phage PhiC31 integrase-mediated gene delivery is believed to be safer than using retroviral vectors since the protein confines its insertion of the target gene to a limited number of sites in mammalian genomes. To evaluate its safety in human cells, it is important to understand the interactions between this integrase and cellular proteins. Here we show that PhiC31 integrase interacts with TTRAP as presented by yeast two-hybrid and co-immunoprecipitation assays. Reducing the expression of endogenous TTRAP can increase the efficiency of PhiC31 integrase-mediated integration. A possible effect of interaction between PhiC31 integrase and TTRAP was highlighted by the fact that PhiC31 integrase inhibited the NFkappaB activation mediated by IL-1 in a dose-dependent manner. Because low dose of PhiC31 integrase can mediate considerable recombination events, we suggest that low dose of PhiC31 integrase be used when this integrase is applied in human cells.

Vector retargeting for cancer gene therapy.

Vector tropism is a research hot spot in cancer gene therapy, and targeted viral vectors play a key role in the enhancement of safety and efficiency in cancer gene therapy. Vector retargeting is one of the important strategies on viral vector targeting. This review mainly focused on the progresses of vector retargeting in cancer gene therapy, and summarized relevant pathways and strategies.

TTRAP is a novel PML nuclear bodies-associated protein.

PML nuclear body (PML NB) is an important macromolecular nuclear structure that is involved in many essential aspects of cellular function. Tens of proteins have been found in PML NBs, and promyelocytic leukemia protein (PML) has been proven to be essential for the formation of this structure. Here, we showed that TRAF and TNF receptor-associated protein (TTRAP) was a novel PML NBs-associated protein. TTRAP colocalized with three important PML NBs-associated proteins, PML, DAXX and Sp100 in the typical fashion of PML NBs. By yeast mating assay, TTRAP was identified to interact with these PML NBs-associated proteins. The transcription and expression of TTRAP could be induced by IFN-gamma, representing another common feature of PML NBs-associated proteins. These results would not only be important for understanding PML NBs but also be helpful in studying the TTRAP function in the future.

[Preparation of rAAV2/hFIX and experimentally application to gene therapy for hemophilia B].

OBJECTIVE: To prepare the rAAV2/hFIX and evaluate the efficiency of the preparation on gene therapy of hemophilia B model mice. METHODS: The rAAV-2/hFIX was prepared by "one helper virus-one vector cell line" strategy and transfected both BHK-21 and C2C12 cells in vitro. The hFIX antigen level in cell culture supernatant was assayed. The rAAV-2/hFIX was injected into muscles of hemophilia B model mice and assayed the serum hFIX levels, hFIX clotting activity, bleeding time, 5 min bleeding volume. RESULTS: The hFIX antigen could be detected from 24 h till 120 h after BHK-21 and C2C12 cells were transfected with highest levels at 24 h reaching (51.0 +/- 6.5) ng/10(5) cells and (68.0 +/- 7.2) ng/10(5) cells, respectively. The rAAV2/hFIX injected mice could efficiently express hFIX and peaked at three weeks after injection, then slowly decreased but low level hFIX antigen was still detectable till 10 weeks after injection. There were significant differences between the high, middle and low dose groups of rAAV2/hFIX and the control group (P < 0.01), the plasma FIX clotting activities in the model mice were improved remarkably, bleeding time was greatly shortened and bleeding in 5 min was decreased. The hFIX expression level and FIX clotting activity of the high dose of rAAV2/hFIX group (1.6 x 10(13) v.g./kg) reached about (387.0 +/- 12.5) ng/ml plasma in contrast with the normal levels of (30.0 +/- 5.5)% at the third week after injection. No rAAV2 vector DNA was detected in the organs except for injected muscle tissue. CONCLUSION: The rAAV2/hFIX transfected BHK-21 and C2C12 cells could efficiently express hFIX antigen and was of therapeutic effects for the hemophilia B model mice by intramuscularly injection.The results provide the basis for clinical trial of rAAV2 gene therapy for hemophilia B.

Hybrid retroviral vector with MCK enhancers inserted in LTR for stable and specific expression of human factor IX in skeletal muscle.

BACKGROUND: Retroviral vectors have been widely used to introduce foreign into various target cells in vitro, thus showing relatively high systemic delivery efficiency of various transgene products. The authors investigated the stability and efficiency of skeletal muscle-specific hybrid retroviral vectors in expression of human factor IX (FIX) in vitro and iv vivo. METHODS: FIX cDNA in LIXSN vector was replaced with a FIX minigene containing splicing donor and splicing acceptor sequence of first intron of human FIX gene. Two copies of muscle creatine kinase enhancer (MCK, Me2) were inserted in forward or reverse orientation at NheI site of 3' long terminal repeat (LTR), resulting in two hybrid vectors, which were designated as LMe2IXm2SN(F) and LMe2IXm2SN(R), respectively. The vectors were tested in vitro and in vivo for stability and muscle-specificity of factor IX expression with SCID mice. RESULTS: Muscle cells carrying vector with Me2 expressed significantly higher levels of FIX (up to 1800 ng/106.24 h) than those without Me2, thus suggesting that Me2 could specifically increase expression level of FIX in muscle cells. Myoblasts transduced with LMe2IXm2SN(R) produced much less FIX in vivo in SCID mice than LMe2IXm2SN(F). One or two copies of Me2 sequence were deleted in myoblasts transduced with LMe2IXm2SN(R) without changing the orientation of Me2. CONCLUSIONS: LTR inserted with MCK enhancers can specifically increase human FIX expression in skeletal muscle cells in vitro and in vivo, and MCK enhancer should be positioned in the same orientation as that of LTR promoter.

Molecular cloning and expression of a smooth muscle-specific gene SM22alpha in zebrafish.

SM22alpha is a kind of 22-kDa protein which is exclusively expressed in smooth muscle containing tissues of the vertebrates. Here we report molecular cloning of a novel zebrafish SM22alpha gene. The full length of zebrafish SM22alpha cDNA is 1296bp and it encodes a polypeptide of 201 amino acids which shares 69.2%, 69.7%, 69.2%, 67.2%, and 61.2% overall identity with human, mouse, rat, chicken, and bovine SM22alpha, respectively. Characterization of zebrafish SM22alpha genomic sequence reveals that it spans 7.7kb and contains five exons and four introns. The expression pattern of SM22alpha in zebrafish embryonic development is studied by whole-mount in situ hybridization. Strong expression is observed in vascular, gut, swim bladder, branchial arches, and fin epidermis. Furthermore, we carry out gene knock-down by antisense morpholino oligonucleotide, which results in disappearance of yolk extension, caudal fin aberrance, and deficiency of circulation system in zebrafish embryo. Cross-section of SM22alpha-deficient embryo suggests that SM22alpha may play roles in smooth muscle cell morphology transform.

Generation and characterization of transgenic mice expressing tamoxifen-inducible cre-fusion protein specifically in mouse liver.

AIM: To establish transgenic mice expressing tamoxifen-inducible Cre-ERt recombinase specifically in the liver and to provide an efficient animal model for studying gene function in the liver and creating various mouse models mimicking human diseases. METHODS: Alb-Cre-ERt transgenic mice were produced by microinjecting the construct with Cre-ERt fusion gene of DNA fragments into fertilized eggs derived from inbred C57BL/6 strain. Transgenic mice were identified by using PCR and Southern blotting. Expression of Cre-ERt fusion gene was analyzed in the liver, kidney, brain and lung from F1 generation transgenic mice at 8 weeks of age by reverse transcription (RT)-PCR. RESULTS: Four hundred and fourteen fertilized eggs of C57 BL/6 mice were microinjected with recombinant Alb-Cre-ERt DNA fragments, and 312 survival eggs injected were transferred to the oviducts of 12 pseudopregnant recipient mice, 6 of 12 recipient mice became pregnant and gave birth to 44 offsprings. Of the 44 offsprings, two males and one female carried the hybrid Cre-ERt fusion gene. Three mice were determined as founders, and were back crossed to set up F1 generations with other inbred C57BL/6 mice. Transmission of Cre-ERt fusion gene in F1 offspring followed Mendelian rules. The expression of Cre-ERt mRNA was detected only in the liver of F1 offspring from two of three founder mice. CONCLUSION: Transgenic mice expressing tamoxifen-inducible Cre-ERt recombinase under control of the liver-specific promoter are preliminary established.

[Vesicular stomatitis virus G-protein retrovector mediated a herpes simplex virus thymidine kinase gene transduction and expression in the human retinal pigment epithelial cells].

OBJECTIVE: The herpes simplex virus-thymidine kinase suicide gene (HSV-TK) was delivered to the human retinal pigment epithelial cell (RPE) by a new vesicular stomatitis virus G protein (VSV-G) retroviral vector. The growth inhibitory effects of ganciclovir on VSV-G/HSV-TK transfected RPE were studied. METHODS: A VSV-G retrovirus-packaging cell line 293GPG was transferred with retroviral vector plasmas bearing HSV-TK (G1NaCTK) or galactosidase (LacZ gene, G1BgSvNa) to produce a 293GPG/TK cell line or a 293GPG/LacZ cell line, respectively. LacZ activity was assessed following transduction of CRL2302 cells. HSV-TK transfected RPE and NIH3T3 cells (at different titer levels) were treated with ganciclovir. The growth inhibitory effects of ganciclovir on various cell lines were studied. RESULTS: The titer of VSV-G/HSV-TK concentration was 1.2 x 10(8) cfu/ml. At a high titer (MOI = 200), the efficiency of LacZ gene transfer in CRL2302 cells was 58%. Ganciclovir inhibited the growth of cells transfected by HSV-TK. The maximum inhibitory rate (45%) was obtained at cells with a high titer (MOI = 200). CONCLUSION: Our results suggested that VSV-G/LacZ and VSV-G/HSV-TK retroviral vectors are highly efficient for in vitro delivery and stable expression of genes in NIH3T3 cells and human RPE cells. The cells modified by HSV-TK gene are very sensitive to ganciclovir and the cell growth can be inhibited by ganciclovir.

Construction of a recombinant vector based on AAV carrying human endothelial nitric-oxide synthase gene.

AIM: To construct an AAV based vector carrying human endothelial nitric-oxide synthase (eNOS) cDNA and study its expression in vitro for future gene therapy. METHODS: eNOS cDNA was inserted into the EcoR I site of pSNAV-1 containing the cytomegalovirus (CMV) promoter and inverted terminal repeat sequences of adeno-associated virus. The constructed vector was transfected into BHK and C2C12 cells. eNOS cDNA and mRNA were detected by polymerase chain reaction (PCR) and reverse transcription-PCR (RT-PCR), respectively. RESULTS: By restriction enzyme digestion analysis, it was proved that eNOS cDNA was inserted into pSNAV-1 in a proper direction. PCR detection demonstrated that pSNAV-eNOS was transferred into both BHK and C2C12 cells. RT-PCR analysis showed that these pSNAV-eNOS transfected cells could express eNOS mRNA. CONCLUSION: pSNAV-eNOS was successfully constructed with the ability to express human eNOS mRNA in cultured mammalian cells.