The expression of the cancer/testis antigen, A-kinase anchor protein 4 (AKAP-4), has been evaluated in prostate cancer (PC) patients.

The exploitation tumor-associated antigens, not only for screening purposes, but also as targets for tumor immunotherapy underlines their relevance in oncology and is due to features frequently shared by molecular biomarkers and tumor antigens.

Scientists at Texas Technical University (Lubbock, TX, USA) analyzed normal prostate tissues, 15 patients with PC and the LnCAP PC cell line by immunohistochemistry. The immunogenicity of AKAP-4 was tested through indirect enzyme-linked immunosorbent assay (ELISA) on sera from cancer patients and healthy subjects. In vitro AKAP-4-specific cytotoxic lymphocytes were generated from peripheral blood mononuclear cells. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to measure AKAP-4 messenger ribonucleic acid (mRNA) expression.

The AKAP-4 was shown both at the cytoplasmic and surface levels of the LnCAP PC cell line. AKAP-4 was also highly expressed in PC cells from patients. Specific anti-AKAP-4 circulating immunoglobulins were detected in AKAP-4 positive subjects. The use of recombinant AKAP-4-loaded autologous dendritic cells generated AKAP-4-specific and human leukocyte antigen-1 (HLA-I)-restricted cytotoxic T lymphocytes able to kill PC cells in vitro. Further characterization indicated a T-helper cell (Th-1) skewing in the cytokine secretion profile of these cells.

The indirect ELISA was performed using specific reagents from Pierce (Rockford, IL, USA) and the ELISA for T Cell Cytokine Expression used sandwich ELISA kits from U-CyTech (Utrecht, The Netherlands). The authors concluded that the aberrant expression of AKAP-4 in PC will potentially be developed as a biomarker in PC and is a potential target for immunotherapy. The study was published in the January 2012 issue of the journal the Prostate.

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Texas Technical University
Pierce
U-CyTech