Enhanced T-cell immunity induced by dendritic cells with phagocytosis of heat shock protein 70 gene-transfected tumor cells in early phase of apoptosis

Abstract

The dual role of heat shock protein 70 (HSP70), as antigenic peptide chaperone and danger signal, makes it especially important in dendritic cell (DC)-based vaccination. In this study, we investigated the impacts of apoptotic transgenic MCA/HSP tumor cells expressing HSP70 on DC maturation, T-cell stimulation and vaccine efficacy. We found that DCs with phagocytosis of MCA/HSP in early phase of apoptosis expressed more pMHC I complexes, stimulated stronger cytotoxic T lymphocyte (CTL) responses (40% specific killing at an E:T cell ratio of 50) and induced immune protection in 90% of mice against MCA tumor cell challenge, compared with 25% specific CTL killing activity and 60% immune protection seen in mice immunized with DC with phagocytosis of MCA/HSP in late phase of apoptosis (Po0.05). Similar results were confirmed in another EG7 tumor model also expressing HSP70. Taken together, our data demonstrate that HSP70 on apoptotic tumor cells stimulate DC maturation, and DC with phagocytosis of apoptotic tumor cells expressing HSP70 in early phase of apoptosis more efficiently induced tumor-specific CTL responses and immunity than DCs with phagocytosis of apoptotic tumor cells in late phase of apoptosis. These results may have an important impact in designing DC-based antitumor vaccines.

Immunogenic cancer cell death: a key-lock paradigm

“…Bortezomib induces the expression of heat shock protein 90 (hsp90) on the surface of dying human myeloma tumor cells, and it is the geldanamycin-inhibitable recognition of such tumor cells by DC that leads to the generation of anti-tumor T cells [17]. Similarly, in preclinical experiments, manipulation designed to increase the expression of HSPs such as local hyperthermia applied to tumors [18], infection with HSP70-encoding oncolytic viruses or transfection with HSP70 followed by irradiation [19] can increase immunogenicity. Extracellular targeting of the ER chaperone glucose-regulated protein 170 (GRP170) also enhances the immunogenicity of tumor cells [20].…”

Abrogation of Local Cancer Recurrence After Radiofrequency Ablation by Dendritic Cell-based Hyperthermic Tumor Vaccine

“…Furthermore, HSPs deliver maturation signals to DCs by upregulating the expression of costimulatory and antigenpresenting molecules, including CD80, CD86, and MHC (major histocompatibility complex) class II molecules. [17][18][19] More importantly, it is conceivable that heat shocked tumor cell lysatepulsed DCs (HTDCs) might be able to prime a set of tumorspecific T cells that could more efficiently recognize and eradicate the surviving heatshocked tumors cells till remain unkilled by RFA treatment. To test this possibility, we evaluated the effect of combining RFA with HTDC vaccination on the poorly immunogenic B16F10luc melanoma.…”

Tumor Apoptotic Bodies Inhibit CTL Responses and Antitumor Immunity via Membrane-Bound Transforming Growth Factor-β1 Inducing CD8+ T-Cell Anergy and CD4+ Tr1 Cell Responses

“…23). These splenic DC cultured in the above medium containing OVA (0.5 mg/mL) and in the above medium with irradiated (9,000 rad) P815 tumor cells at a ratio of 1:2 for overnight (22) were termed DC OVA and DC P815 , respectively.…”

“…EG7 tumor cells were in vitro irradiated with different doses (3,000, 6,000, 9,000, and 12,000 rad) of irradiation, and irradiated tumor cells were further cultured in DMEM plus 10% FCS and G418 (0.5 mg/mL) for different lengths (3,6,9, and 12 h) of time. These irradiated tumor cells were stained with propidium iodide (PI) and FITC-Annexin V using an Annexin V-FITC Apoptosis Detection kit (Pharmingen) as well as ECD-anti-TGF-h1 antibody and analyzed by flow cytometry (22). Tumor cell lines such as EL4, P815, and SP2/0 and other tumor cell lines such as 3LL, F1, and MCA26 were irradiated with 9,000 and 20,000 rad, respectively.…”

“…Recently, we have shown that the apoptotic EG7 tumor cells expressing HSP70 in early phase of apoptosis more efficiently induced DC maturation and vaccine efficiency than those in late phase of apoptosis (22). In this study, we purified APB derived from irradiation-induced apoptotic EG7 tumor cells and investigated its potential immune modulation in OVA-pulsed DC (DC OVA )-induced antitumor immune responses.…”