Sperm protein 17 is expressed in human nervous system tumours.
BACKGROUND
Human sperm protein 17 (Sp17) is a highly conserved protein that was originally isolated from a rabbit epididymal sperm membrane and testis membrane pellet. It has recently been included in the cancer/testis (CT) antigen family, and shown to be expressed in multiple myeloma and ovarian cancer. We investigated its immunolocalisation in specimens of nervous system (NS) malignancies, in order to establish its usefulness as a target for tumour-vaccine strategies.


METHODS
The expression of Sp17 was assessed by means of a standardised immunohistochemical procedure [(mAb/antigen) MF1/Sp17] in formalin-fixed and paraffin embedded surgical specimens of NS malignancies, including 28 neuroectodermal primary tumours (6 astrocytomas, 16 glioblastoma multiforme, 5 oligodendrogliomas, and 1 ependymoma), 25 meningeal tumours, and five peripheral nerve sheath tumours (4 schwannomas, and 1 neurofibroma).


RESULTS
A number of neuroectodermal (21%) and meningeal tumours (4%) were found heterogeneously immunopositive for Sp17. None of the peripheral nerve sheath tumours was immunopositive for Sp17. The expression pattern was heterogeneous in all of the positive samples, and did not correlate with the degree of malignancy.


CONCLUSIONS
The frequency of expression and non-uniform cell distribution of Sp17 suggest that it cannot be used as a unique immunotherapeutic target in NS cancer. However, our results do show the immunolocalisation of Sp17 in a proportion of NS tumour cells, but not in their non-pathological counterparts. The emerging complex function of Sp17 makes further studies necessary to clarify the link between it and immunopositive cells.
Grizzi
Fabio
F
Istituto Clinico Humanitas, IRCCS, 20089 Rozzano, Milan, Italy. fabio.grizzi@humanitas.it
Gaetani
Paolo
P
Franceschini
Barbara
B
Di Ieva
Antonio
A
Colombo
Piergiuseppe
P
Ceva-Grimaldi
Giorgia
G
Bollati
Angelo
A
Frezza
Eldo E
EE
Cobos
E
E
Rodriguez y Baena
Riccardo
R
Dioguardi
Nicola
N
Chiriva-Internati
Maurizio
M
D000368:Aged; D000954:Antigens, Surface; D014408:Biomarkers, Tumor / Q000032:analysis*; D001932:Brain Neoplasms / Q000737:chemistry; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins / Q000032:analysis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D009423:Nervous System Neoplasms / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000954:Antigens, Surface; D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C090172:SPA17 protein, human