The receptor encoded by the human C-MET oncogene is expressed in testicular tissue and on human spermatozoa

Because of its distinctive ability to act as a mitogen, a mitogen and a morphogen, hepatocyte growth factor/scatter factor (HGF/SF) has all the characteristics of a molecule able to function in regulatory networks of motility, such as the spermatogenic epithelium, and this through binding of its receptor p190(MET) (C-MET). In this study we report the expression of C-MET in the human seminiferous epithelium and on spermatozoa from men being treated for infertility and sperm donors. The presence of C-MET was demonstrated by immunochemistry on the cell membrane of spermatogonia, spermatocytes, spermatids and on spermatozoa, whereas Sefton cells and Leydig cells did not show expression. Comparison of C-MET expression on spermatozoa of the 90% Percoll layer of subfertile patients and donors revealed clearly two distinct groups (unpaired t-test, P < 0.001), whereas comparison of C-MET expression on spermatozoa in the 47% Percoll layer was not significantly different between patients and donors. In addition, there was a significant inverse correlation between sperm concentration and the C-MET expression of spermatozoa in the 90% Percoll layer (r = -0.80, 95% confidence interval, -0.92 to -0.55; P < 0.0001), but not with the C-MET expression of spermatozoa in the 47% Percoll layer. In conclusion, the presence of C-MET was demonstrated in the seminiferous epithelium and on mature and immature spermatozoa, indicating a role for this growth factor receptor in the differentiation and/or migration that occurs during human spermatogenesis.