Normal and pathological human testes express hormone-sensitive lipase and the lipid receptors CLA-1/SR-BI and CD36.
Numerous studies have demonstrated the important role of cholesterol and cholesteryl esters in tumor cell proliferation and progression of cancer. However, few studies have focused on the role of lipid transporters and lipases in cancer development and progression. The present study examined the expression of hormone-sensitive lipase (HSL) and the scavenger receptors CLA-1/SR-BI and CD36 in normal human testis and in nontumor and tumor testicular disorders by immunohistochemistry and Western blotting analysis. In normal young testes, immunoreaction to CLA-1/SR-BI was found in the spermatid acrosomic vesicle and on the surface of Sertoli and Leydig cells. HSL was detected in spermatogonia, the Golgi region of spermatocytes, the nucleus of spermatids, and the cytoplasm of both Sertoli and Leydig cells. Elderly testes and testes with hypospermatogenesis showed a similar staining pattern to that of normal young testes except for CD36, which was expressed in Sertoli cells. Cryptorchid testes demonstrated intense labeling to HSL and weak labeling to SR-BI in Sertoli cells (nucleus and cytoplasm) and Leydig cells (cytoplasm). Seminiferous tubules with intratubular germ cell neoplasia exhibited intense immunolabeling to the 3 lipid receptors in the surface of neoplastic cells and to HSL in the nucleus. In seminoma and spermatocytic seminoma, neoplastic cells labeled to HSL but failed to stain with antilipid receptors; in the seminiferous tubules at the periphery of the tumour, Charcot-Böttcher crystalloids of Sertoli cells were strongly positive to CLA-1. Testes with mature teratoma showed a weak reaction to CD36 and SR-BI in some cells of enteric-type glands, and immature teratoma were exclusively immunolabeled with HSL. Western blotting analysis revealed that multiple bands were immunolabeled, with differences seen between normal and pathological testes. The results of this study indicate that the presence of lipid receptors (CLA-1/SR-BI) and hormone-sensitive lipase in Leydig cells suggests a role of these proteins in steroidogenesis. Also, these proteins seem to be involved in spermiogenesis, as their labeling in spermatids suggests. In nonmalignant and malignant pathologies, cholesterol metabolism is probably altered, and HSL labeling in neoplastic germ cell nuclei suggests a still-unknown function of this enzyme, probably related to cell cycle regulation.
Arenas
Maria I
MI
Department of Cell Biology and Genetics, University of Alcalá, Alcalá de Henares, Madrid, Spain.
Lobo
Maria V T
MV
Caso
Enrique
E
Huerta
Lidia
L
Paniagua
Ricardo
R
Martín-Hidalgo
Martin A
MA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D018955:CD36 Antigens / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D008297:Male; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein / Q000378:metabolism*; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D002787:Sterol Esterase / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000201:enzymology* / Q000473:pathology
D018955:CD36 Antigens; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C495124:SCARB1 protein, human; D051122:Scavenger Receptors, Class B; D002787:Sterol Esterase