Vesicular stomatitis virus matrix protein gene enhances the antitumor effects of radiation via induction of apoptosis

Delivery of modified mRNA encoding vesicular stomatitis virus matrix protein for colon cancer gene therapy

Plasmid DNA based gene delivery has been widely utilized among both pre-clinical and clinical gene therapy studies. However, therapeutic efficiency is usually limited by the size and potential immune-stimulation issue of plasmid backbone. As an alternative form of genetic material, chemically modified messenger RNA (mRNA) provides a promising alternative to plasmid DNA. In this work, an in vitro transcription mRNA encoding vesicular stomatitis virus matrix protein (VSVMP) was delivered by a cationic liposome–protamine complex, resulting in high mRNA transporting and expression efficiency. The liposome–protamine complex delivered VSVMP mRNA strongly inhibits the growth of C26 tumor cells through inducing apoptosis, while obvious tumor regressions were achieved on both abdominal cavity metastatic and subcutaneous xenograft models in vivo with high safety. Our results also demonstrated that the liposome–protamine–mRNA complex was as potent as its plasmid DNA counterpart, showing strong potential in further colon cancer therapy.

Liposome–protamine complex delivered VSVMP mRNA efficiently inhibits C26 colon carcinoma with safety, providing an alternative strategy for non-viral gene therapy.

Ovarian cancer treatment with a tumor-targeting and gene expression-controllable lipoplex

Overexpression of folate receptor alpha (FRα) and high telomerase activity are considered to be the characteristics of ovarian cancers. In this study, we developed FRα-targeted lipoplexes loaded with an hTERT promoter-regulated plasmid that encodes a matrix protein (MP) of the vesicular stomatitis virus, F-LP/pMP_(2.5), for application in ovarian cancer treatment. We first characterized the pharmaceutical properties of F-LP/pMP_(2.5). The efficient expression of the MP-driven hTERT promoter in SKOV-3 cells was determined after an in-vitro transfection assay, which was significantly increased compared with a non-modified LP/pMP_(2.5) group. F-LP/pMP_(2.5) treatment significantly inhibited the growth of tumors and extended the survival of mice in a SKOV-3 tumor model compared with other groups. Such an anti-tumor effect was due to the increased expression of MP in tumor tissue, which led to the induction of tumor cell apoptosis, inhibition of tumor cell proliferation and suppression of tumor angiogenesis. Furthermore, a preliminary safety evaluation demonstrated a good safety profile of F-LP/pMP_(2.5) as a gene therapy agent. Therefore, FRα-targeted lipoplexes with therapeutic gene expression regulated by an hTERT promoter might be a promising gene therapy agent and a potential translational candidate for the clinical treatment of ovarian cancer.

Livin modulates the apoptotic effects of vesicular stomatotitis virus in lung adenocarcinoma

Vesicular stomatitis virus (VSV) has shown promise in cancer treatment. However, it achieved limited effects against lung cancer. Lung cancer has intrinsic mechanisms that render resistance to VSV. In this study, we attempted to explore the expression of the anti-apoptotic factor Livin in lung adenocarcinoma and its possible relationship to VSV vulnerability. We found VSV induced apoptosis in a time- and dose-dependent manner, with the concomitant change in the expression of Livin. We elevated the expression of Livin both transiently and stably, and the cells became insensitive to VSV treatment. We further found the BIR domain of Livin was mainly responsible for its modulation effects. This finding suggested a possible interaction with the second mitochondria-derived activator of caspase (SMAC). The knock-down of SMAC also inhibited apoptosis by VSV. The relationship was confirmed by the co-immunoprecipitation. Finally, we knocked down the endogenous Livin, and the knock-down sensitized cells to VSV treatment. Our results suggested the important role of Livin and its partner molecule in the process of VSV treatment.

RNA interference targeting human FAK and EGFR suppresses human non-small-cell lung cancer xenograft growth in nude mice

Transfection of plasmid vectors coexpressing short hairpin RNA (shRNA) for focal adhesion kinase (FAK) and epidermal growth factor receptor (EGFR) significantly inhibited protein level of FAK and EGFR. Knockdown of FAK and EGFR expression significantly inhibited cell proliferation and induced cell apoptosis of A549 lung cancer cells in vitro. In A549 subcutaneous xenograft model, mice treated for 3 weeks with plasmid that coexpresses FAK and EGFR shRNA had significantly smaller tumors than those in control mice (P < 0.01). FAK and EGFR dual silencing also significantly decreased microvessel density, tumor cell proliferation and increased the level of apoptosis in tumor cells. Moreover, administration with plasmid that coexpresses FAK and EGFR shRNA significantly inhibited the A549 experimental lung metastases. Collectively, our data suggest that the dual inhibition of FAK and EGFR by using plasmid vector-based RNA interference might be a novel therapeutic approach to the treatment of human NSCLC.

Gene therapy using the human telomerase catalytic subunit gene promoter enables targeting of the therapeutic effects of vesicular stomatitis virus matrix protein against human lung adenocarcinoma

The catalytic subunit of telomerase, human telomerase reverse transcriptase (hTERT), is highly active in immortalized cells and more than 90% of human cancer cells, but is quiescent in the majority of normal somatic cells. Thus, the hTERT promoter has been extensively used in targeted cancer gene therapy. Vesicular stomatitis virus (VSV) matrix protein (MP) induces the apoptosis of tumor cells in the absence of other viral components. In our previous studies, we successfully constructed the pVAX-M plasmid from the pVAX plasmid, which expressed wild-type VSV MP (VSV MP is under the control of the CMV promoter) and demonstrated that pVAX-M efficiently suppresses the growth of malignant tumors via the induction of apoptosis in vitro and in vivo. The present study was designed to construct the plasmid phTERTM (VSV MP is under the control of the hTERT promoter) and investigate whether it had a targeted antitumor effect in nude mice bearing human lung adenocarcinoma. In vitro, A549 human lung adenocarcinoma cells were treated with NS, Lip-null, etoposide, Lip-pVAX-M or Lip-phTERT-M, and examined for cell viability through MTT assays or for apoptosis by flow cytometry and TUNEL assays. In vivo, A549 human lung carcinoma models in nude mice were established. Mice were treated with 10 4-weekly intravenous administrations of NS, Lip-null, etoposide (2 mg/kg), Lip-pVAX-M or Lip-phTERT-M. Subsequently, Lip-phTERT-M was found to be the most efficient inhibitor of tumor growth and inducer of tumor cell apoptosis when compared with the other groups in vivo and in vitro (P<0.05). Notably, immunohistochemical staining showed that Lip-phTERT-M significantly limited the overexpression of VSV MP to the tumor tissues and reduced VSV MP expression in other organs in comparison with Lip-pVAX-M (P<0.05). Therefore, it can be concluded that phTERT-M demonstrates a targeted antitumor effect on A549 human lung adenocarcinoma cells. These observations suggest that phTERT-M gene therapy may be a novel and potent strategy for targeting human lung adenocarcinoma.

Vesicular stomatitis virus matrix protein (VSVMP) inhibits the cell growth and tumor angiogenesis in oral squamous cell carcinoma

The purpose of this study was to investigate the anticancer property of vesicular stomatitis virus matrix protein (VSVMP) in oral squamous cell carcinoma (OSCC) via in vitro and in vivo approaches. In this study, we found that OSCC cells treated with VSVMP showed retarded cell growth in vitro. The percentage of apoptotic cells in VSVMP group was much higher than that of the control groups. Moreover, our in vivo experiments showed that the growth of tumor xenografts was significantly suppressed by VSVMP treatment without any obvious side effects. Further studies revealed that the suppression of tumor growth may be caused by the synergistic effect of VSVMP related cell apoptosis enhancing and tumor angiogenesis suppression, and the latter is most likely correlated with the suppression of VEGF pathway. This study indicated that VSVMP treatment can effectively inhibited the cell growth and tumor angiogenesis in OSCC without obvious adverse effects. Therefore, VSVMP might be a potential and efficient strategy for OSCC treatment.

Vesicular stomatitis virus as a treatment for colorectal cancer

M protein mutant vesicular stomatitis virus is an attractive candidate oncolytic virus for the treatment of metastatic colorectal cancer due to its ability to kill cancer cells that are defective in their antiviral responses. The oncolytic activity of recombinant wild-type and M protein mutant vesicular stomatitis viruses was determined in RKO, Hct116 and LoVo colorectal cancer cells, as well as in human fibroblast and hepatocyte primary cultures. RKO and Hct116 cells were sensitive to both viruses, whereas LoVo cells were resistant. [(35)S]methionine labeling experiments and viral plaque assays showed that sensitive and resistant colorectal cancer cells supported viral protein and progeny production after infection with either virus. Colorectal cancer cells were pretreated with β-interferon and infected with vesicular stomatitis virus to evaluate the extent to which interferon signaling is downregulated in colorectal cancer cells. Although colorectal cancer cells retained some degree of interferon signaling, this signaling did not negatively impact the oncolytic effects of either virus in sensitive cells. Murine xenografts of RKO cells were effectively treated by intratumoral injections with M protein mutant virus, whereas LoVo xenografts were resistant to treatment with this virus. These results suggest that M protein mutant vesicular stomatitis virus is a good candidate oncolytic virus for the treatment of selected metastatic colorectal cancers.

The attitude of oncology physicians and nurses to the acceptance of new drugs for gene therapy

With the efficacy of gene therapy verified in phase III trials, cancer patients will consider whether to accept gene therapy sooner or later. The purpose of this study is to investigate the attitudes of oncology physicians and nurses regarding effective gene therapy. A questionnaire was administered to 368 oncology physicians and nurses. A total of 328 valid questionnaires were returned (response rate, 89.1%). Gene therapy was considered as very safe or safe by 256 (78.0%) participants. Regardless of the stage of cancer, participants who advised patients to enroll in clinical trials and considered gene therapy as safe tended to accept the effective gene therapy. Gene therapy is considered to be a safe treatment. Most participants are willing to accept effective and verified gene therapy on the assumption that they themselves suffer from cancers.

Efficient inhibition of C-26 colon carcinoma by VSVMP gene delivered by biodegradable cationic nanogel derived from polyethyleneimine

Biodegradable cationic nanoparticles have promising application as a gene delivery system. In this article, heparin-polyethyleneimine (HPEI) nanogels were prepared, and these nanogels were developed as a nonviral gene vector. The transfection efficiency of HPEI nanogels was comparable with that of PEI25K, while the cytotoxicity was lower than that of PEI2K and much lower than that of PEI25K in vitro. These HPEI nanogels also had better blood compatibility than PEI25K. After intravenous administration, HPEI nanogels degraded, and the degradation products were excreted through urine. The plasmid expressing vesicular stomatitis virus matrix protein (pVSVMP) could be efficiently transfected into C-26 colon carcinoma cells by HPEI nanogels in vitro, inhibiting the cell proliferation through apoptosis induction. Intraperitoneal injection of pVSVMP/HPEI complexes efficiently inhibited the abdominal metastases of C-26 colon carcinoma through apoptosis induction (mean tumor weight in mice treated with pVSVMP/HPEI complex = 0.93 g and in control mice = 3.28 g, difference = 2.35 g, 95% confidence interval [CI] = 1.75-2.95 g, P < 0.001) and prolonged the survival of treated mice. Moreover, intravenous application of pVSVMP/HPEI complexes also inhibited the growth of pulmonary metastases of C-26 colon carcinoma through apoptosis induction. The HPEI nanogels delivering pVSVMP have promising application in treating colon carcinoma.

Efficient inhibition of non-small-cell lung cancer xenograft by systemic delivery of plasmid-encoding short-hairpin RNA targeting VEGF

Vascular endothelial growth factor (VEGF) plays an important role in the growth and metastasis of non-small-cell lung cancer (NSCLC). The aim of this study was to develop an RNA-interference approach that targets VEGF, using a recombinant plasmid, and to explore its antitumor efficacy in NSCLC in vivo. shRNA-targeting VEGF was cloned into pGenesil-2 plasmid vector and then transfected into A549 human lung cancer cells, using cationic liposome. Reverse-transcriptase polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) analysis were used to evaluate the silencing effects of VEGF-shRNA on A549 cells in vitro. Further, the growth-inhibition capacity of VEGF-shRNA on A549 lung carcinoma xenografts was tested in nude mice. Proliferation, apoptosis, and angiogenesis in tumor tissues were measured by PCNA, TUNEL, and CD31 immunohistochemistry, respectively. shRNA-targeting VEGF significantly silenced VEGF expression in A549 lung cancer cells, as confirmed by RT-PCR and ELISA assay (P < 0.01). In vivo, the VEGF-shRNA delayed tumor growth and reduced tumor weight by approximately 61.96%, compared with control groups (P < 0.05), accompanied with angiogenesis inhibition (P < 0.01) and apoptosis induction (P < 0.01). Our data showed that the knockdown of VEGF by shRNA might be a potential therapeutic approach against human NSCLC.

Combination of vesicular stomatitis virus matrix protein gene therapy with low-dose cisplatin improves therapeutic efficacy against murine melonoma

Vesicular stomatitis virus (VSV) matrix protein (MP) can directly induce apoptosis via the mitochondrial pathway due to the inhibition of host gene expression. Our previous studies have demonstrated that MP gene therapy efficiently suppressed the growth of malignant tumor in vitro and in vivo. The present study was designed to determine the possibility that the combination of MP gene therapy with low-dose cisplatin would improve therapeutic efficacy against murine melanoma. Immunocompetent C57BL/6 mice bearing B16-F10 melanoma were established. Mice were treated once every 5 days with i.v. administration of 10 microg pVAX-MP/30 microg liposome complex per mouse for 16 days and i.p. delivery of cisplatin at 4 mg/kg/mouse on days 6 and 12 after the initiation of MP treatment. We found that MP + cisplatin treatment resulted in significant inhibition of tumor growth and improved the survival time of melanoma-bearing mice. MP successfully inhibited angiogenesis as assessed by CD31. Histological examination revealed that the combination therapy led to significant increased induction of apoptosis, tumor necrosis, and elevated CD8(+) lymphocyte infiltration. Furthermore, the induction efficacy of the CTL response was dramatically enhanced by the combination therapy. Our findings may prove useful in further explorations of the application of these combinational approaches to the treatment of malignant melanoma.

Apoptosis induction in BEFV-infected Vero and MDBK cells through Src-dependent JNK activation regulates caspase-3 and mitochondria pathways

Our previous report demonstrated that bovine ephemeral fever virus (BEFV)-infected cultured cells could induce caspase-dependent apoptosis. This study aims to further elucidate how BEFV activates the caspase cascade in bovine cells. BEFV replicated and induced apoptosis in Vero and Madin-Darby bovine kidney (MDBK) cells, and a kinetic study showed a higher efficiency of replication and a greater apoptosis induction ability of BEFV in Vero cells. Src and c-Jun N-terminal kinase (JNK) inhibitor, but not extracellular signal-regulated kinase (ERK) or p38 inhibitor, alleviated BEFV-mediated cytopathic effect and apoptosis. In BEFV-infected Vero and MDBK cells, BEFV directly induced Src tyrosine-418 phosphorylation and JNK phosphorylation and kinase activity, which was inhibited specifically by SU6656 and SP600125, respectively. The caspase cascade and its downstream effectors, Poly (ADP-ribose) polymerase (PARP) and DFF45, were also activated simultaneously upon BEFV infection. In addition, cytochrome c, but not Smac/DIABLO, was released gradually from mitochondria after BEFV infection. SU6656 suppressed Src, JNK, and caspase-3 and -9 activation, as well as PARP and DFF45 cleavage; SP600125 reduced JNK and caspase-3 and -9 activation, as well as PARP and DFF45 cleavage. Taken together, these results strongly support the hypothesis that a Src-dependent JNK signaling pathway plays a key role in BEFV-induced apoptosis. The molecular mechanism identified in our study may provide useful information for the treatment of BEFV.