Infertility has been stated as a risk factor for
testicular cancer; but currently, there is no prognostic
indicator of
tumor development from the pathologic testis with impaired spermatogenesis. Regenerating
proteins are expressed in many human tissues including the testis, and their role in
carcinogenesis has been well documented. In the present work, regenerating I
messenger RNA and
protein expression and cellular
protein localization were studied in testicular biopsies of patients with normal (obstructive
azoospermia) or impaired spermatogenesis (
nonobstructive azoospermia) and in
seminoma testis by quantitative
reverse transcriptase-polymerase chain reaction, Western blot, and immunofluorescence analyses. No significant differences in regenerating I transcripts were reported between the 3 groups studied. However, regenerating I
protein was highly expressed in pure
seminoma and in
placental-like alkaline phosphatase-positive seminiferous tubules with in situ
carcinoma. Regenerating I
protein levels measured by Western blotting increased from the
placental-like alkaline phosphatase-negative distal region of the
seminoma to the pure
placental-like alkaline phosphatase-positive tumoral region. Importantly, although cells localized in seminiferous tubules of obstructive azoospermic patients with normal spermatogenesis were very slightly labeled, persisting germ, Sertoli, and myoid cells and fibrous tissues were strongly regenerating I positive in seminiferous tubules of
nonobstructive azoospermia. These results suggest the possibility to use regenerating I as a prognostic marker of tumoral development in the infertile testis.