Sperm-Associated Antigen 9, a Novel Cancer Testis Antigen, Is a Potential Target for Immunotherapy in Epithelial Ovarian Cancer

Abstract

Purpose: Cancer testis antigens are a group of tumor antigens with gene expression restricted to male germ cells in the testis and in various cancerous tissues. Recently, we reported a novel testisspecific sperm-associated antigen 9 (SPAG9) gene, a new member of the c-Jun NH 2 -terminal kinase^interacting protein family, having functional role in sperm-egg fusion and mitogenactivated protein kinase signaling pathway. National Center for Biotechnology Information Blast searches revealed SPAG9 nucleotide sequence similarities with expressed sequence tags of various cancerous tissues. In an effort to examine the clinical utility of SPAG9, we investigated the SPAG9 mRNA and protein expression in epithelial ovarian cancer (EOC). Humoral immune response to SPAG9 was also evaluated in EOC patients. Experimental Design: We determined the expression profile of SPAG9 transcript by reverse transcription-PCR and RNA in situ hybridization and SPAG9 protein expression by immunohistochemistry in EOC specimens and human ovarian cancer cell lines. Using ELISA and Western blotting, we analyzed specific antibodies for SPAG9 in sera from patients with EOC. Results: SPAG9 mRNA and protein expression was detected in 90% of EOC tissues and in all three human ovarian cancer cell lines. Specific SPAG9 antibodies were detected in 67% of EOC patients and not in sera from healthy individuals. Conclusions: Our findings indicate that SPAG9 is highly expressed in EOC and immunogenic in patients. Humoral immune response against SPAG9 in early stages of EOC suggests its important role in early diagnostics.These results collectively suggest that SPAG9, a novel member of cancer testis antigen family, could be a potential target for the development of diagnostic and therapeutic methods in EOC.

Sperm‐associated antigen 9 is a biomarker for early cervical carcinoma

“…10,11 We recently reported on the expression of a new member of the CT antigen family, sperm-associated antigen 9 (SPAG9), in patients with epithelial ovarian cancer (EOC). 13 We also demonstrated the presence of humoral immune response against SPAG9 in EOC patients. In addition, gene expression microarray analysis of cervix carcinoma cells 14 found the SPAG9 gene expressed along with other important much-studied genes.…”

“…17 SPAG9 protein expression in 4-lm paraffin-embedded sections (serial sections) of cervical cancer tissues was analyzed with anti-SPAG9 antibody or control immunoglobulin (Ig) G by immunohistochemistry as described earlier. 13 Paraffinembedded sections of ANCT were also processed as described earlier. 13 To confirm the grades of the cervical tumor, serial tumor sections were incubated with mouse monoclonal antiproliferating cell nuclear antigen (PCNA [F-2]; Santa Cruz Biotechnology, Calif) at a dilution of 1:50 at 4 C overnight in a humid chamber.…”

“…13 Paraffinembedded sections of ANCT were also processed as described earlier. 13 To confirm the grades of the cervical tumor, serial tumor sections were incubated with mouse monoclonal antiproliferating cell nuclear antigen (PCNA [F-2]; Santa Cruz Biotechnology, Calif) at a dilution of 1:50 at 4 C overnight in a humid chamber. After washing, antigen-bound primary antibodies were detected by horseradish peroxidase-conjugated goat antimouse IgG (Jackson ImmunoResearch Laboratories, West Grove, Pa).…”

“…All ANCT and tumor tissues were immediately snap frozen and stored at À80 C for gene expression as described earlier. 13 …”

A novel cancer testis antigen target A-kinase anchor protein (AKAP4) for the early diagnosis and immunotherapy of colon cancer

“…8,9 Interestingly, none of these studies reported humoral response against CT antigens except OY-TES-1 which demonstrated that only 9.6% (7/73) patients generated auto-antibodies. 7 The most studied SPAG9 in various malignancies [20][21][22][23][24][25] was also shown to be associated with CRC in various stages and histotypes. 6 SPAG9 was also found to be highly immunogenic and demonstrated humoral response in CRC patients.…”