SK1 Immunolocalization in Head and Neck Cancer.

FACCHINETTI, MM; GANDINI, N; FERMENTO M.E.; NORMA STERIN-SPEZIALE; YOUNMI,JI; VYOMESH,P; GUTKIND, SJ; RIVADULLA, M; CURTINO, AC

CELLS TISSUES ORGANS

KARGER

Lugar: Basilea; Año: 2010 vol. 188 p. 384 - 392

1422-6405

Sphingosine kinase 1 (SK1) is a key enzyme in the sphingolipid metabolic pathway responsible for catalyzing the formation of sphingosine-1-phosphate (S1P) which has been shown to stimulate cell growth, differentiation, angiogenesis and migration, and to inhibit apoptosis. Much is known regarding SK1 involvement in tumorigenesis although few studies actually address SK1 immunolocalization in human tumors. In this study, immunohistochemical distribution of SK1 was examined in head and neck squamous cell carcinoma. An initial screening for SK1 expression was performed in a tissue array consisting in 291 samples of squamous cell carcinomas, 15 non-tumor head and neck samples and 32 normal tissues. The results show that 85% of samples (154) are positive for SK1 with different staining intensities, whereas only 2 of the 15 non-tumor head and neck show staining. Additionally, 25 samples of regular paraffin-embedded tissue were studied for SK1 expression. Tumor areas exhibited overwhelmingly positive immunostaining for SK1 as compared with normal adyacent areas of the tumors. Strong immunoreactivity was evident in epithelial cells being mainly cytoplasmic. No staining was seen in stromal cells. In order to corroborate if squamous cell carinomas present different SK1 expression than their normal adjacent tissue, laser capture microdissection was performed in samples belonging to 4 HNSCC patiens, and SK1 mRNA extracted was quantified by RT-PCR. Pooled data of four patients showed an increase expression in tumor areas compared with their adjacent tissue. These results show immunolocalization of SK1 in squamous cell carcinoma and help define a role for this protein in tumor progression.