Blocked By Co-suppression Of Signaling Pathways Joint Chemotactic Antigen Gene-modified Tumor Cell Vaccine Treatment Of Cancer Research

In this study, To establish a more efficient treatment for immunotherapy against prostate tumor, we demonstrate that an effective immune response against prostate tumors in mouse tumor model can be elicited using a strategy that combines CTLA-4 or B7-H1 blockade and pSLC-3P-Fc-modified tumor cell vaccine (named B16F10-SLC-3P-Fc).We previously reported that several DNA fragments from human prostate-specific membrane antigen (hPSM), mouse prostatic acid phosphatase (mPAP) and human prostate-specific antigen (hPSA) genes were selected and fused to create a novel hPSM-mPAP-hPSA fusion gene (named 3P gene), and human secondary lymphoid tissue chemokine (SLC), 3P and human IgG Fc genes were inserted into pcDNA3.1 to construct a DNA vaccine, designated pSLC-3P-Fc. In this report, to establish a more efficient treatment for immunotherapy against prostate cancer, the construct was transfected into B16F10 to generate gene-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). In poorly immunogenic B16F10 mouse melanoma model, the immunization with B16F10-SLC-3P-Fc resulted in a strong antitumor response. The combined therapy of B16F10-SLC-3P-Fc plus anti-CTLA-4 (or anti-B7-H1) mAbs further enhanced the immune response. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8~+ T cells and CD4~+ T lymphocytes were required for the induction of CD8~+ CTL response in B16F10-SLC-3P-Fc＋anti-CTLA-4 (or anti-B7-H1) mAb-immunized mice. Moreover, mice that were cured of an established tumor were protected against a rechallenge with the same tumor for at least 4 months, suggesting the generation of memory responses. Adoptive transfer experiments further indicate that antitumor reactivity can be transferred to naive mice by splenocytes. These findings demonstrate that the combinatorial treatment can elicit a potent anti-tumor immune response and suggest potential of this approach for treatment of prostate cancer.We also found effective immune responses against TC-1 tumor cells when anti-CTLA-4 and anti-B7-H1 mAb were combined at the same time. Our findings demonstrate that the combination therapy could possibly have an synergetic effect in tumor rejection. To clone an extracellular region of human CTLA-4 and construct an immunoglobulin IgG Fc fusion protein expression vector, cDNA fragment was amplified by reverse transcription methods followed by PCR from the total RNA of PHA activated human peripheral blood mononuclear cells, and connected with IgG Fc. Then fusion gene CTLA-4-Fc was inserted into pHIgV to construct fusion protein expression vector. For further research the expression vector was transfected into CHO-dhfr~- cells, the expression of CTLA-4-Fc gene was confirmed by RT-PCR.