RESUMO
Vesicular stomatitis virus (VSV) matrix (M) protein can directly induce apoptosis by inhibiting host gene expression when it is expressed in the absence of other viral components. Previously, we found that the M protein gene complexed to DOTAP-cholesterol liposome (Lip-MP) can suppress malignant tumor growth in vitro and in vivo; however, little is known regarding the biological effect of Lip-MP combined with radiation. The present study was designed to determine whether Lip-MP could enhance the antitumor activity of radiation. LLC cells treated with a combination of Lip-MP and radiation displayed apparently increased apoptosis compared with those treated with Lip-MP or radiation alone. Mice bearing LLC or Meth A tumors were treated with intratumoral or intravenous injections of Lip-MP and radiation. The combined treatment significantly reduced mean tumor volumes compared with either treatment alone in both tumor models and prolonged the survival time in Meth A tumor models and the intravenous injection group of LLC tumor models. Moreover, the antitumor effects of Lip-MP combined with radiation were greater than their additive effects when compared with the expected effects of the combined treatment in vivo. This study suggests that Lip-MP enhanced the antitumor activity of radiation by increasing the induction of apoptosis.
Assuntos
Apoptose/efeitos da radiação , Raios gama , Terapia Genética , Neoplasias/genética , Neoplasias/radioterapia , Proteínas da Matriz Viral/genética , Proteínas da Matriz Viral/uso terapêutico , Animais , Linhagem Celular Tumoral , Proliferação de Células , Ácidos Graxos Monoinsaturados/metabolismo , Lipossomos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Neoplasias/patologia , Compostos de Amônio Quaternário/metabolismo , Ensaio Tumoral de Célula-TroncoRESUMO
Colorectal cancer is one of the most common cancers. Survivin is strongly immunogenic in a fraction of colorectal cancer patients. The present study was designed to determine whether full-length mouse Survivin dominant-negative mutant SurvivinT34A has the antitumor activity in a murine colon carcinoma model. The complex of cationic liposome (DOTAP/Chol) to plasmid pORF9-mSurvivin T34A was administered intravenously in a mouse subcutaneous (S. C.) CT 26 tumor model. Apoptotic cells and anti-angiogenesis were evaluated by fluorescent in situ TUNEL assay and by immunohistochemistry with an antibody reactive to CD31, respectively. A 4 h 51Cr release assay was performed to determine Survivin-specific cytotoxicity. The adoptive transfer of CD8+ or CD4+ T-lymphocytes assay was to further explore the roles of immune cell subsets. We demonstrated the complex of cationic liposome (DOTAP/Chol) to plasmid pORF9--mSurvivin T34A when administered intravenously induced an efficient antitumor activity in a S. C. CT26 tumor model in mice. The main mechanism is involved in three aspects: triggering the apoptosis of tumor cells, inhibiting angiogenesis, and inducing Survivin-specific immune response. Our observations may have potential implications for the further exploration of the treatment of human colorectal cancer by intravenous delivery of dominant-negative mutant Survivin T34A.