Blood cells and their use in active immunotherapy of prostate cancer

Vascular endothelial growth factor suppresses dendritic cells function of human prostate cancer

Purpose

Prostate cancer (PCa) patients often have dendritic cell (DC) function defects, but the mechanism is not clear. The aim of this study was to detect the effect of vascular endothelial growth factor (VEGF) in mature DCs.

Patients and methods

In this study, we chose 30 PCa patients, 10 prostatic intraepithelial neoplasia (PIN) patients and 30 benign prostatic hyperplasia (BPH) patients, and compared the composition of peripheral blood T cells, the composition and function of local dendritic cells in prostate tissue, and the density of local VEGF.

Results

The results showed that the numbers of total DCs, mature and functional DCs, and CD4⁺ T cells were inhibited in PCa, and the inhibitory effect was enhanced with increased malignancy. In addition, the infiltration density of VEGF-positive cells was increased in PCa, and this increase was associated with an increased malignant degree of PCa. The inhibition of tumor immunity in patients with PCa is achieved by inhibiting the function of dendritic cells.

Conclusion

VEGF plays an important role in the inhibition of the maturation and function of dendritic cells, and this inhibition is gradually increased with an increasing malignant degree of PCa.

Anti-CD27 Antibody Potentiates Antitumor Effect of Dendritic Cell-Based Vaccine in Prostate Cancer-Bearing Mice

In the current study, we investigated whether anti-CD27 monoclonal antibody can enhance the antitumor efficacy of a dendritic cell-based vaccine in prostate cancer-bearing mice. The overall therapeutic effect of a dendritic cell-based vaccine for prostate cancer remains moderate. A prostate cancer model was established by subcutaneous injection of RM-1 tumor cells into male C57BL/6 mice on day 0. After 4 days, tumor-bearing mice were treated with RM-1 tumor lysate-pulsed dendritic cells (i.e., dendritic cell-based vaccine), anti-CD27 monoclonal antibody, or a combination of RM-1 tumor lysate-pulsed dendritic cells with anti-CD27 monoclonal antibody. Mice were killed at 21 days after tumor cell implantation. Tumor size was measured for assessment of antitumor effect. Spleens were collected for analysis of antitumor immune responses. The antitumor immune responses were evaluated by measuring the proliferation and activity of T cells, which have the ability to kill tumor cells. The combination therapy with RM-1 tumor lysate-pulsed dendritic cells and anti-CD27 antibody significantly enhanced T-cell proliferation and activity, and significantly reduced tumor growth, compared with monotherapy with RM-1 tumor lysate-pulsed dendritic cells or anti-CD27 antibody. Our results suggest that combined treatment can strengthen antitumor efficacy by improving T-cell proliferation and activity.