Identification of nucleolar protein No55 as a tumour-associated autoantigen in patients with prostate cancer

Four different genes were identified by immunoscreening of a cDNA expression library from the human prostate cancer cell line DU145 with allogeneic sera from four prostate cancer patients. A cDNA encoding the nucleolar protein No55 was further analysed and shown to be expressed at the mRNA level in several normal tissues, including ovaries, pancreas and prostate and in human prostate cancer cell lines PC-3, PC-3m and LNCaP. By reverse transcriptase/polymerase chain reaction, expression of No55 was several-fold higher in two out of nine prostate cancer primary tumours and two out of two metastatic lesions, compared to normal prostate tissue. Antibodies to No55 were detected in sera from seven out of 47 prostate cancer patients but not in sera from 20 healthy male controls. Sequence analysis of the No55 open reading frame from normal and tumour tissues revealed no tumour-specific mutations. The No55 gene was located to chromosome 17q21, a region reported to be partially deleted in prostate cancer. Considering the immunogenicity of the No55 protein in the tumour host, the expression profile and chromosomal localization of the corresponding gene, studies evaluating No55 as a potential antigen for immunological studies in prostate cancer may be warranted. © 2000 Cancer Research Campaig

Immunotherapy with allotumour mRNA-transfected dendritic cells in androgen-resistant prostate cancer patients

Here, we present results from a clinical trial employing a new vaccination method using dendritic cells (DCs) transfected with mRNA from allogeneic prostate cancer cell lines (DU145, LNCaP and PC-3). In all, 20 patients were enrolled and 19 have completed vaccination. Each patient received at least four weekly injections with 2 × 107 transfected DCs either intranodally or intradermally. Safety and feasibility of vaccination were determined. Immune responses were measured as delayed-type hypersensitivity and by in vitro immunoassays including ELISPOT and T-cell proliferation in pre- and postvaccination peripheral blood samples. Serum prostate-specific antigen (PSA) levels and bone scans were monitored. No toxicity or serious adverse events related to vaccinations were observed. A total of 12 patients developed a specific immune response to tumour mRNA-transfected DCs. In total, 13 patients showed a decrease in log slope PSA. This effect was strengthened by booster vaccinations. Clinical outcome was significantly related to immune responses (n=19, P=0.002, r=0.68). Vaccination with mRNA-transfected DCs is safe and results in cellular immune responses specific for antigens encoded by mRNA derived from the prostate cancer cell lines. The observation that in some patients vaccination affected the PSA level suggests that this approach may become useful as a treatment modality for prostate cancer patients

Monoclonal hybridoma antibodies to human amyloid related protein SAA.

Problems concerning isolation and characterization of the amyloid related serum protein SAA in a pure form prompted us to make monoclonal antibodies to the protein. Protein SAA isolated by gel filtration under dissociating conditions was used for immunization of BALB/c mice, and spleen cells from a mouse producing high titred antiserum to SAA were fused with cells from the mouse plasmacytoma line P3U1. Antibody specificity to various preparations of protein SAA was tested using an indirect enzyme-linked immunosorbent assay. Monoclonal antibodies with specificity for SAA were obtained in addition to antibodies which reacted with both SAA and the related amyloid protein AA. Antibodies specific for one of the apoC proteins of the lipoprotein fraction were also produced showing that the SAA preparation used for immunization was contaminated with apoC proteins