Cancer Vaccine Therapy Using Tumor Endothelial Cells as Antigens Suppresses Solid Tumor Growth and Metastasis.

Tumor angiogenesis plays an important role in tumor growth and metastasis, with tumor cells requiring nutrients and oxygen via blood flow for their proliferation. In comparison, angiogenesis also occurs under normal physiological conditions, such as wound healing and in the formation of the corpus luteum. Herein, we report on the development of a novel dendritic cell (DC) vaccine therapy using tumor endothelial cells (TECs) derived from tumor vessels as tumor antigens. After density gradient centrifugation and the detection of angiotensin-converting enzyme activities, a TEC-rich fraction was separated from solid tumor tissues. Prophylactic or therapeutic immunization using DCs pulsed with TECs as vaccine antigens significantly suppressed solid tumor growth in a Colon-26 colorectal adenocarcinoma tumor-bearing mouse model, compared with the use of tumor cells as DC vaccine antigens. Tumor tissues showed reduced angiogenesis. However, vaccination using DCs pulsed with TECs did not inhibit physiological angiogenesis as evidenced by a wound healing assay. Additionally, in a B16/BL6 mouse melanoma lung metastasis model, DC vaccination using TECs derived not only from the same tumor tissue but from a different type of tumor also suppressed metastasis. These results thus show that cancer vaccine therapy targeting TECs is an effective therapy against angiogenesis in several types of cancer, but does not affect normal blood vessel growth.

Suppression of murine collagen-induced arthritis by vaccination of synovial vascular endothelial cells.

AIMS: Endothelial cells (ECs) lining the lumina of blood vessels are involved in leukocyte extravasation underlying inflammatory states, such as rheumatoid arthritis (RA). The rheumatoid pannus, the site of inflammation and joint destruction in the rheumatoid synovium, relies on the development of neovascular vessels to sustain its growth. We studied a method to selectively target and destroy new synovial blood vessels by vaccination with synovial EC. MAIN METHODS: Collagen-induced arthritis (CIA) mice were vaccinated with tumor necrosis factor (TNF)-alpha-stimulated EC (TNF-EC) antigen with an incomplete adjuvant. TNF-EC was used as a model of EC in synovial tissue on RA. KEY FINDINGS: Arthritis was significantly decreased in TNF-EC vaccinated mice compared with non-vaccinated mice based on the arthritis score. Moreover, the TNF-EC vaccine suppressed bone erosion, hyperplasia of the synovium and expression of neovascular vessel as shown by hematoxylin-eosin staining, X-ray analysis and immunohistochemical. SIGNIFICANCE: Vaccine therapy against vascular EC in synovial tissue may provide a novel approach to the treatment of RA.

Prophylactic immunization with Bubble liposomes and ultrasound-treated dendritic cells provided a four-fold decrease in the frequency of melanoma lung metastasis.

Melanoma has an early tendency to metastasize, and the majority of the resulting deaths are caused by metastatic melanoma. It is therefore important to develop effective therapies for metastasis. Dendritic cell (DC)-based cancer immunotherapy has been proposed as an effective therapeutic strategy for metastasis and recurrence due to prime tumor-specific cytotoxic T lymphocytes. In this therapy, it is important that DCs present peptides derived from tumor-associated antigens on MHC class I molecules. Previously, we developed an innovative approach capable of directly delivering exogenous antigens into the cytosol of DCs using perfluoropropane gas-entrapping liposomes (Bubble liposomes, BLs) and ultrasound. In the present study, we investigated the prevention of melanoma lung metastasis via DC-based immunotherapy. Specifically, antigens were extracted from melanoma cells and used to treat DCs by BL and ultrasound. Delivery into the DCs by this route did not require the endocytic pathway. The delivery efficiency was approximately 74.1%. DCs treated with melanoma-derived antigens were assessed for in vivo efficacy in a mouse model of lung metastasis. Prophylactic immunization with BL/ultrasound-treated DCs provided a four-fold decrease in the frequency of melanoma lung metastases. These in vitro and in vivo results demonstrate that the combination of BLs and ultrasound is a promising method for antigen delivery system into DCs.

Cancer gene therapy by IL-12 gene delivery using liposomal bubbles and tumoral ultrasound exposure.

Interleukin-12 (IL-12) gene therapy is expected to be effective against cancers because it primes the immune system for cancer cells. In this therapy, it is important to induce IL-12 gene expression in the tumor tissue. Sonoporation is an attractive technique for developing non-invasive and non-viral gene delivery systems, but simple sonoporation using only ultrasound is not an effective cancer gene therapy because of the low efficiency of gene delivery. We addressed this problem by combining ultrasound and novel ultrasound-sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. Our previous work showed that this is an effective gene delivery system, and that Bubble liposome collapse (cavitation) is induced by ultrasound exposure. In this study, we assessed the utility of this system in cancer gene therapy using IL-12 corded plasmid DNA. The combination of Bubble liposomes and ultrasound dramatically suppressed tumor growth. This therapeutic effect was T-cell dependent, requiring mainly CD8(+) T lymphocytes in the effector phase, as confirmed by a mouse in vivo depletion assay. In addition, migration of CD8(+) T cells was observed in the mice, indicating that the combination of Bubble liposomes and ultrasound is a good non-viral vector system in IL-12 cancer gene therapy.