Local expression of secondary lymphoid tissue chemokine delivered by adeno-associated virus within the tumor bed stimulates strong anti-liver tumor immunity.

Development of an effective antitumor immune response depends on the appropriate interaction of effector and target cells. Thus, the expression of chemokines within the tumor may induce a more potent antitumor immune response. Secondary lymphoid tissue chemokine (SLC) is known to play a critical role in establishing a functional microenvironment in secondary lymphoid tissues. Its capacity to attract dendritic cells (DCs) and colocalize them with T cells makes it a good therapeutic candidate against cancer. In this study, we used SLC as a treatment for tumors established from a murine hepatocellular carcinoma model. SLC was encoded by recombinant adeno-associated virus (rAAV), a system chosen for the low host immunity and high efficiency of transduction, enabling long-term expression of the gene of interest. As a result, rAAV-SLC induced a significant delay of tumor progression, which was paralleled by a profound infiltration of DCs and activated CD4(+) T cells and CD8(+) T cells (CD3(+) CD69(+) cells) into the tumor site. In addition, rAAV-SLC treatment was also found to reduce tumor growth in nude mice, most likely due to inhibition of neoangiogenesis. In conclusion, local expression of SLC by rAAV represents a promising approach to induce immune-mediated regression of malignant tumors.