Protein disulfide isomerase A3-specific Th1 effector cells infiltrate colon cancer tissue of patients with circulating anti-protein disulfide isomerase A3 autoantibodies.

To investigate novel colorectal cancer (CRC)-associated antigens that could be targets of humoral or cellular responses, we analyzed the reactivity of serum from a long-surviving CRC patient (for more than 100 months of follow-up) in clinical remission, by serologic proteome analysis. Two-dimensional Western blotting (2D-WB) and mass spectrometry analysis revealed a strong reactivity of this serum against protein disulfide isomerase A3 (PDIA3). Anti-PDIA3 antibodies are not a diagnostic marker of CRC, 2D-WB and Luminex analysis revealed that they were equally present in about 10% of sera from healthy subjects and CRC patients. Kaplan-Meier analysis of survival in CRC patient cohort, after 48 months of follow-up, showed a trend of higher survival in patients with increased levels of autoantibodies to PDIA3. Therefore, the interplay between the presence of these antibodies and T-cell response was investigated. Peripheral blood T cells from CRC patients with high immunoglobulin G (IgG) reactivity to PDIA3 also secreted interferon gamma (IFN-γ) when stimulated in vitro with recombinant PDIA3, whereas those from CRC with low IgG reactivity to PDIA3 did not. PDIA3-pulsed dendritic cells efficiently induced proliferation and IFN-γ production of autologous CD4(+) and CD8(+) T cells. Finally, ex vivo analysis of tumor-infiltrating T lymphocytes from CRC patients with autoantibodies to PDIA3 revealed that PDIA3-specific Th1 effector cells accumulated in tumor tissue. These data indicate that the presence of autoantibodies to PDIA3 favors the development of an efficient and specific T-cell response against PDIA3 in CRC patients. These results may be relevant for the design of novel immunotherapeutic strategies in CRC patients.

Targeting of surface alpha-enolase inhibits the invasiveness of pancreatic cancer cells.

Pancreatic Ductal Adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by rapid progression, invasiveness and resistance to treatment. We have previously demonstrated that most PDAC patients have circulating antibodies against the glycolytic enzyme alpha-enolase (ENO1), which correlates with a better response to therapy and survival. ENO1 is a metabolic enzyme, also expressed on the cell surface where it acts as a plasminogen receptor. ENO1 play a crucial role in cell invasion and metastasis by promoting plasminogen activation into plasmin, a serine-protease involved in extracellular matrix degradation. The aim of this study was to investigate the role of ENO1 in PDAC cell invasion. We observed that ENO1 was expressed on the cell surface of most PDAC cell lines. Mouse anti-human ENO1 monoclonal antibodies inhibited plasminogen-dependent invasion of human PDAC cells, and their metastatic spreading in immunosuppressed mice was inhibited. Notably, a single administration of Adeno-Associated Virus (AAV)-expressing cDNA coding for 72/1 anti-ENO1 mAb reduced the number of lung metastases in immunosuppressed mice injected with PDAC cells. Overall, these data indicate that ENO1 is involved in PDAC cell invasion, and that administration of an anti-ENO1 mAb can be exploited as a novel therapeutic option to increase the survival of metastatic PDAC patients.