Intratumoral Administration of Secondary Lymphoid Chemokine and Unmethylated Cytosine-phosphorothioate-guanine Oligodeoxynucleotide Synergistically Inhibits Tumor Growth in Vivo

Secondary lymphoid tissue chemokine (SLC), which is expressed in T cell zones of secondary lymphoid organs, including the spleen and lymph nodes, strongly recruits both T lymphocytes and mature dendritic cells. As appropriate interaction of tumor-specific T cells and mature dendritic cells, equipped with tumor antigens, is a prerequisite for effective T cell immunity against established tumors, we mobilized lymphocytes and dendritic cells to tumor sites by intratumoral injection of secondary lymphoid tissue chemokine-Fc (SLC-Fc) fusion protein using the B16F10 murine melanoma model. Activation of dendritic cells, another prerequisite for the effective activation of naive tumor-specific T cells, was achieved by the addition of immunostimulatory cytosine-phosphorothioate-guanine oligodeoxynucleotide (CpG-ODN) into the tumor site. Intratumoral administration of SLC-Fc or CpG-ODN revealed antitumor effects against B16F10 murine melanoma grown in the subcutaneous space. Co-treatment of SLC-Fc and CpG-ODN displayed synergistic effects in reducing the tumor size. The synergistic antitumor effect in co-treatment group was correlated with the synergistic/additive increase in the infiltration of CD4+ T cells and CD11c+ dendritic cells in the tumor mass compared to the single treatment groups. These results suggest that the combined use of chemokines and adjuvant molecules may be a possible strategy in clinical tumor immunotherapy.

Nanoemulsão contendo 7-cetocolesterol (LDE/7KC) promove inibição do crescimento de malanoma em camundongos e aumento de sobrevida / A 7-ketocholesterol containing-nanoemulsion (LDE/7KC) inhibits growth of melanoma tumor in mice and increases survival rate

7-cetocoleterol (7KC) é um oxisterol conhecido por inibir a proliferação celular e por ser citotóxico. Uma nanoemulsão contendo 7KC (LDE/7KC) demonstrou efeito anti-proliferativo sobre as linhagens RPMI 8226 (mieloma) e melanoma (B16F10), in vitro. Sendo preferencialmente captada via receptores de LDL. No presente trabalho, avaliamos, in vivo, a cinética plasmática, biodistribuição e ação anti-tumoral em camundongos portadores de melanoma. A nanoemulsão dirigiu-se principalmente no fígado e ao tumor, demonstrando direcionamento a tecidos com alta expressão de receptores para LDL. LDE/7KC promoveu uma redução superior a cinqüenta por cento do tamanho do tumor, que apresentou maior área de necrose e menor quantidade de vasos e aumentou a sobrevida dos camundongos, sem causar toxicidade.

7-ketocholesterol (7KC) is an oxysterol known to inhibit cell proliferation and to be cytotoxic. A nanoemulsion containing-7KC (LDE/7KC) was shown to had antiproliferative effects on RPMI 8226 myeloma cell line and melanoma (B16F10), in vitro. This particle is taken up mainly by LDL receptors. Here we have evaluated the plasma kinetic, biodistribution and the anti-tumoral action of LDE/7KC in melanoma bearing mice. The nanoemulsion accumulated in the liver and tumor, tissues with a high expression of LDL receptors. LDE/7KC promoted a tumor size reduction over fifty percent. A increased necrosis area and a decreased amount of blood vessels was found. A increased survival rate was observed, together with a lack of toxicicity.

Activated natural killer cell-mediated immunity is required for the inhibition of tumor metastasis by dendritic cell vaccination

Immunization with dendritic cells (DCs) pulsed with tumor antigen can activate tumor-specific cytotoxic T lymphocytes (CTL), which is responsible for tumor protection and regression. In this study, we examined whether DCs pulsed with necrotic tumor lysates can efficiently prevent malignant melanoma tumor cell metastasis to the lung. DCs derived from mouse bone marrow were found to produce remarkably elevated levels of IL-12 after being pulsed with the tumor lysates. Moreover, immunization with these DCs induced CTL activation and protected mice from metastasis development by intravenously inoculated tumor cells. In addition, these DCs activated NK cells in vitro in a contact-dependent manner, and induced NK activities in vivo. Furthermore, NK cell depletion before DC vaccination significantly reduced the tumor-specific CTL activity, IFN-g production, and IFN-gamma- inducible gene expression, and eventually interfered with the antitumor effect of tumor-pulsed DCs. Finally, similar findings with respect to NK cell dependency were obtained in the C57BL/ 6J-bg/bg mice, which have severe deficiency in cytolytic activity of NK cells. These data suggest that the antitumor effect elicited by DC vaccination, at least in a B16 melanoma model, requires the participation of both cytolytic NK and CD8+ T cells. The findings of this study would provide important data for the effective design of DC vaccines for cancer immunotherapy.

Purificación parcial de antígenos de menbrana para la obtención de antisueros que reconocen al melanoma B-16 / Parcial purification of membrane antigens for obtaining anti-sera recornizing melanma B-16

Se obtuvieron antisueros que reconocen selectivamente a melanocitos normales y malignos de ratón mediante 2 formas de inmunización: con cèlulas enteras del melanoma murino B-16 y con una fracción semipurificada de menbrana de dichas células. El reconocimiento de los antisueros fue ensayado por técnicas de ELISA e inmunofluorescencia contra melanoma y otros tejidos. Se concluyó que los antisueros obtenidos por inmunización con la fracción purificada presentaron un reconocimiento más especìfico de los melanocitos