Shinya Gomi

Contribution of CD95 Ligand-Induced Neutrophil Infiltration to the Bystander Effect in p53 Gene Therapy for Human Cancer

Clinical trials of adenoviral p53 gene therapy provide the evidence that the bystander effect induced by the wild-type p53 gene transfer on adjacent tumor cells contributes to tumor progression; its mechanism, however, remains uncharacterized. We report in this work that injection of adenovirus expressing the human wild-type p53 gene (Ad5CMVp53) into established human colorectal tumors in nu/nu mice resulted in CD95 ligand (CD95L) overexpression, followed by a massive neutrophil infiltration. Culture supernatants of human colorectal cancer cells infected with Ad5CMVp53 exhibited a potent chemotactic activity against murine polymorphonuclear neutrophils, which could be abolished by the anti-CD95L mAb (NOK-1). In vivo cell depletion experiments indicated that neutrophils were in part responsible for the antitumor effect of the Ad5CMVp53 infection. Our data directly suggest that overexpression of CD95L by the wild-type p53 gene transfer induces neutrophil infiltration into human colorectal tumors, which may play a critical role in the bystander effect of p53 gene therapy.

Antitumor Effect of Intratumoral Administration of Bone Marrow-Derived Dendritic Cells Transduced with Wild-Type p53 Gene

Purpose: Dendritic cells (DCs) are attractive effectors for cancer immunotherapy because of their potential to function as professional antigen-presenting cells for initiating cellular immune responses. The tumor suppressor gene p53 is pivotal in the regulation of apoptosis, and ∼50% of human malignancies exhibit mutation and aberrant expression of p53. We investigated the antitumor effect of intratumoral administration of bone marrow-derived dendritic cells transduced with wild-type p53 gene. Experimental Design: We examined whether intratumoral administration of DCs infected with recombinant adenovirus expressing murine wild-type p53 (Ad-mp53) could induce systemic antitumor responses against mutant p53-expressing tumors, highly immunogenic MethA, or weakly immunogenic MCA-207 implanted in syngeneic mice. Results: Accumulation of wild-type p53 protein in bone marrow-derived murine DCs could be successfully achieved by Ad-mp53 infection. Treatment with intratumoral injection of Ad-mp53-transduced DCs caused a marked reduction in the in vivo growth of established MethA and MCA-207 tumors with massive cellular infiltrates. Administration of p53-expressing DCs suppressed the growth of both injected MCA-207 tumors and untreated distant MCA-207 tumors, but not unrelated Lewis lung carcinoma tumors, suggesting the augmentation of systemic immunogenicity against MCA-207 tumor cells. Moreover, intratumoral injection of p53-expressing DCs had a greater antitumor effect than did s.c. immunization. Conclusions: Our results indicate that intratumoral administration of DCs expressing murine wild-type p53 leads to significant systemic immune responses and potent antitumor effects in mutant p53-expressing murine cancer models. These findings raise the possibility of using this strategy of intratumoral injection of p53-expressing DCs for human cancer treatment.

Induction of human leukocyte antigen-A26-restricted and tumor-specific cytotoxic T lymphocytes by a single peptide of the SART1 antigen in patients with cancer with different A26 subtypes.

Peptide antigens available for use in specific immunotherapy of patients with cancer have not been fully determined. Although the authors have reported the SART1 gene encoding epitopes recognized by HLA-A2601–restricted and tumor-specific cytotoxic T lymphocytes (CTLs), the HLA-A26 allele is mainly subdivided into A2601, A2602, and A2603 subtypes. In this study, the authors attempted to determine whether the SART1-derived peptide at position 736-744 (KGSGKMKTE) is suitable to induce HLA-A26–restricted and tumor-specific CTLs in patients with cancer who have these subtypes. This peptide induced the HLA-A26 subtype-restricted and tumor-specific CTLs in HLA-A2601+ or HLA-A2603+ peripheral blood mononuclear cells, respectively. It also induced the HLA-A26–restricted CTL activity in HLA-A2602+ peripheral blood mononuclear cells. Therefore, this peptide could be useful for specific immunotherapy of patients with cancer who have any of the three HLA-A26 subtypes.

Establishment and Epitope Analysis of Allo-Specific Cytotoxic T Lymphocytes at a Tumor Site Recognizing a Spouse's HLA-A0206 Molecule

PROBLEM: The molecular basis of allo‐reactivity in reproductive immunity has not been fully clarified.
 METHOD OF STUDY: Cytotoxic T lymphocytes (CTLs) were established from tumor‐infiltrating lymphocytes (TILs). The allo‐reactivity of the CTLs against various tumor cell lines or human leukocyte antigen (HLA)‐A allele‐transfected COS‐7 cells was measured by Cr‐release or interferon‐Γ production assay.
 RESULTS AND CONCLUSIONS: We have established CTLs reacting to an HLA‐A0206 molecule that matched a spouses HLA‐A allele from the TILs of a 68‐year‐old multiparous patient with gastric cancer. The amino acids at positions 66 and 88 in the α1 domain of HLA‐A0206, both of which were common in the other HLA‐A2 subtypes, were involved in the recognition by the CTLs. Endogenous peptides in the groove were not involved in the recognition. These results suggest the presence of long‐lasting memory CTLs raised by the reproduction process, and may facilitate a better understanding of the molecular basis of allo‐recognition during reproduction.