Sperm protein 17 is highly expressed in endometrial and cervical cancers

Abstract

Background: Sperm protein 17 (Sp17) is a highly conserved mammalian protein in the testis and spermatozoa and has been characterized as a tumor-associated antigen in a variety of human malignancies. Many studies have examined the role of Sp17 in tumorigenesis and the migration of malignant cells. It has been proposed as a useful target for tumor-vaccine strategies and a novel marker to define tumor subsets and predict drug response. This study aimed to investigate the expression of Sp17 in endometrial and cervical cancer specimens, its possible correlation with the pathological characteristics, and its value in the diagnosis and immunotherapy of the related cancers.

Methods: The monoclonal antibodies against human Sp17 were produced as reagents for the analysis and immunohistochemistry was used to study two major kinds of paraffin-embedded gynecological cancer specimens, including 50 cases of endometrial cancer (44 adenous and 6 adenosquamous) and 31 cases of cervical cancer (15 adenous and 16 squamous). Normal peripheral endometrial and cervical tissues were used as controls.

Results: Sp17 was found in 66% (33/50) of the patients with endometrial cancer and 61% (19/31) of those with cervical cancer. Its expression was found in a heterogeneous pattern in the cancer tissues. The expression was not correlated with the histological subtype and grade of malignancy, but the staining patterns were different in endometrial and cervical cancers. The hyperplastic glands were positive for Sp17 in the normal peripheral endometrial and cervical tissues in 10% (8/81) of the patients.

Conclusions: Sp17 is highly expressed in human endometrial and cervical cancers in a heterogeneous pattern. Although the expression frequency of Sp17 is not correlated with the histological subtype, the staining pattern may help to define endometrial and cervical cancers. Sp17 targeted immunotherapy of tumors needs more accurate validation.

Figure 1

Production of recombinant human Sp17 and specific identification of hSp17 mAbs by Western blot. A. SDS-PAGE analysis of recombinant human Sp17; B. Specific identification of hSp17 mAb 3C12 by Western blot. Protein from human testis (B1) and ejaculated spermatozoa (B2).

Figure 2

Immunohistochemical characteristics of the Sp17 monoclonal antibody. a. testis from an old patient with prostatic cancer; b. ejaculated spermatozoa; c. EMC staining before blocking; d. EMC staining after blocking.

Figure 3

Immunohistochemistry of Sp17 in the EMC tissues (A-C) and cultured cell line (D). The expression of Sp17 was heterogeneous: A. confertim; B. scattered. C. Sp17 was localized in the cytoplasm and nucleus, with enplaque; D. Sp17 was localized in the cytoplasm, nucleus and membrane. (A, B 10×; C, D 40× original magnification, 100× inset).

Figure 4

Immunohistochemistry of Sp17 in cervical cancer tissues (A-C) and hyperplastic gland (D). The staining pattern of Sp17 was granulo in all the original cervical tissues and located in the cavosurface of adenocancer and the hyperplastic gland. A. squamous cancer; B, C, adenocancer; D. hyperplastic glands in the periphery of the lesions. Sp17 was localized in the cytoplasm but had different intensity. (A, B, D, 20×; C, 40× original magnification, 100× inset).