Introduction

TSGA10 has been described as a 82-kDa protein expressed in testis and during devel-opmental stage of spermatogenesis and em-bryiogenesis (1). It has already been indicated that full-length TSGA10 is post-translational modified, and the processed N-terminus
27-kDa mature TSGA10 is located in the Fi-brous Sheath (FS) of sperm tail (2). However, the C-terminal 55-kDa part of TSGA10 accu-mulates in the midpiece of spermatozoa,


where it co-localizes with HIF-1a, and ex-pressed during brain development (3), and in some solid and nonsolid tumors as a testis-cancer antigen.
The solid tumors include melanoma, pan-creatic adenocarcinoma, hepatocellular car-cinoma (4) and cutaneous lumphoma (5), ovar-ian leiomyosarcoma, germ cell tumor and gas-tric adenocarcinoma (derived ESTs). The non-solid tumors include Acute Lymphocytic Leu-kemia (ALL) and Acute Myeloplastic Leuke-mia (AML) (6,7).
The TSGA10 interacts directly with hyp-oxia inducible factor-1-alpha (3) and contrib-utes to the ciliary structure; thus it may be-have such as VHL. In this study, we have shown the over-expression of TSGA10 in brain tumors, and our eventual goal is to determine its role in brain tumorigenesis.

Materials and Methods

Immunohistochemistry

Result

It has been shown that TSGA10 is ex-pressed in some particular regions of normal brain. The brain regions in which TSGA10 is mainly expressed include the granular layer of cerebellum, hippocampus and subventricular zone (Figure 1). This pattern of TSGA10 ex-pression in the brain suggested a possible high expression of TSGA10 in dividing astrocyte and/or glia cells.
This study has demonstrated TSGA10 over-expression in different pathologic types of human brain tumors with a significant differ-ence compared to normal brain. The signals were scored via a point system by two differ-ent reviewers and final scores were an aver-age of points in different samples by different reviewers.

The brain tumors include glioblastoma, astrocytoma (pilocytic, grades II and III), oligodendroglioma, and medulloblastoma with highest TSGA10 over-expression in grade II oligodendrogliom (average 5+ in three samples) followed by glioblastoma (Table 1, Figure 2 ).
Sixty three samples (dots) have been pro-vided in the tissue array slide with nine differ-ent histopathologic diagnoses including 8 normal brains (1+), 3 medulloblastoma (3+), 12 oligodendroglioma (3 grade II:5+, and 9 grade III:3+), 19 astrocytoma (9 grade II:4+ and 7 grade III:3.9+, and 3 pilocytic:4+), and 21 glioblastoma (4.2+). Medulloblastoma and oligodendroglioma (grade III) generally show

a lower expression of TSGA10 protein com-pared to other tumors. Although TSGA10 protein seems to be expressed more in grades II compared to grade III, this difference is minimal in astrocytoma whereas maximal in oligodendroglioma. Meanwhile, the highest expression of TSGA10 is observed in grade II oligodendroglioma. However, glioblastoma identifies maximum TSGA10 expression as a histopathologic entity among brain tumors (Table 1).
To investigate a possible expression of TSGA10 in an astrocyte, a cell line which was derived from a known human astrocytoma (grade III, WHO, as a gift) selected and endo-genous TSGA10 expression was shown within the cells. Using immunostaining and IF methods, the antibody against the C-terminal of TSGA10 could localize the protein as a single spot around the nucleus, and as several spots within the nucleus, respectively (Figure 3). We also found a significant increase in The TSGA10 expression in this human cell line which was derived from astrocytoma, utilizing protein analysis. Western blot shows a 82 kDa TSGA10 band which was more intense in above-mentioned cell line (astro-cyte derived from grade III astrocytoma) than the astrocyte cell line (A735), as verified by scanning densitometry normalized to ß-actin (Figure 4).

Discussion

It has already been shown that TSGA10 protein has a post-translational modification, resulting in an N-terminus 27-kDa and a
C-terminus 55-kDa components (1). Although the C-terminus TSGA10 may be associated with an organelle such as centrosome which is consistent with its role in cell division and proliferation however a further study in tumor biology is necessary to confirm a precise

and specific function of each component.
In this study, we have demonstrated an over-expression of TSGA10 in brain tumors with a significant difference between normal brain and malignant cells. This is consistent with the previously reported over-expression in some other tumors (4-6; BLAST/NCBI ESTs). The TSGA10 (C-terminus) also inter-acts with HIF-1-alpha (3) and contributes to ciliary-centrosomal structure (1). The results of this study along with prior molecular findings on the TSGA10, may address a crucial role in regulating brain tumorigenesis, apoptosis and hypoxia pathways. These findings on the TSGA10 molecular behavior and expression also remind a similar function to VHL tumor suppresser protein.

Acknowledgement

Authors would like to thank Prof. Sue Povey (UCL, London, UK) for providing the cell line astrocyte which was derived from a known human astrocytoma (grade III, WHO).