Vaccine of engineered tumor cells secreting stromal cell-derived factor-1 induces T-cell dependent antitumor responses

The CXC chemokine SDF-1 has been characterized as a T-cell chemoattractant both in vitro and in vivo. To determine whether SDF-1 expression within tumors can influence tumor growth, we transfected an expression vector pCI-SDF-1 for SDF-1 into J558 myeloma cells and tested their ability to form tumors in BALB/c. Production of biologically active SDF-1 (1.2 ng/mL) was detected in the culture supernatants of cells transfected with the expression vector pCI-SDF-1. J558 cells gave rise to a 100% tumor incidence, whereas SDF-1-expressing J558/SDF-1 tumors invariably regressed in BALB/c mice and became infiltrated with CD4(+) and CD8(+) T cells. Regression of the J558/SDF-1 tumors was dependent on both CD4(+) and CD8(+) T-cells. Our data also indicate that TIT cells containing both CD4(+) and CD8(+) T-cells within J558/SDF-1 tumors express the SDF-1 receptor CXCR4, and that SDF-1 specifically chemoattracts these cells in vitro. Furthermore, immunization of mice with engineered J558/SDF-1 cells elicited the most potent protective immunity against 0.5 x 10(6) cells J558 tumor challenge in vivo, compared to immunization with the J558 alone, and this antitumor immunity mediated by J558/SDF-1 tumor cell vaccination in vivo appeared to be dependent on CD8(+) CTL. Thus, SDF-1 has natural adjuvant activities that may augment antitumor responses through their effects on T-cells and thereby could be important in gene transfer immunotherapies for some cancers.