Does sphingosine kinase 1 (SPHK1) play a role in endometriosis?

Sphingolipids are important constituents of cell membranes, which play key roles as regulatory molecules for various cellular functions. Sphingosine- 1-phosphate produced by sphingosine kinase 1 (SPHK1) promotes cell proliferation, regulates angiogenesis, and influences invasion as well as the attachment of cells. Since these processes are believed to be involved in the development of endometriosis, we analyzed the expression of SPHK1 in human eutopic and ectopic endometrium using immunohistochemistry and microarray analysis. Epithelial cells of both eutopic and ectopic endometrium showed highly variable immunostaining with polyclonal antibody directed against SPHK1. However, strong expression of SPHK1 was largely restricted to the epithelial endometrial cells of peritoneal endometriotic lesions (n = 8/23, 34.8%). Only n = 1/15 (6.7%) of the adenomyosis samples and n = 3/41 (7.3%) of the eutopic endometrium samples displayed strong antigen expression (p = 0.008, X ² test). No association between SPHK1 and Ki-67 expression was detectable. Still further research is needed in order to clarify the role of sphingolipids in the development of endometriosis, and particularly in invasive growth.