The recent development of a prosaposin -/- mouse model has allowed the investigation of the role of prosaposin in the development of the male reproductive organs. A morphometric analysis of the male reproductive system of 37 days old mice revealed that prosaposin ablation produced a 30 % reduction in size and weight of the testes, 37 % of the epididymis, 75 % of the seminal vesicles and 60 % of the prostate glands. Light microscopy (LM) showed that smaller testis size from homozygous mutant mice was associated with reduced spermiogenesis. Both, dorsal and ventral lobules of the prostate glands were underdeveloped in the homozygous mutant. LM analysis also showed that prostatic alveoli were considerably smaller and lined by shorter epithelial cells in the homozygous mutant. Smaller tubular diameter and shorter undifferentiated epithelial cells were also observed in seminal vesicles and epididymis. In the efferent ducts of the homozygous mutant mice, the epithelium was composed exclusively of ciliated cells in contrast to the heterozygotes, which showed the presence of nonciliated cells. Radioimmunoassays demonstrated that testosterone levels were normal or higher in mice with the inactivated prosaposin gene. Immunostaining of prostate sections with an anti-androgen receptor antibody showed that the epithelial cells lining the alveoli express androgen receptor in both the heterozygous and homozygous tissue. Similarly, sections immunostained with antibodies to the phosphorylated MAPKs and Akts strongly reacted with tall prostatic secretory cells in prostate from heterozygous mouse. On the other hand, the epithelial cells in the homozygous prostate remained unstained or weakly stained. These findings demonstrate that inactivation of the prosaposin gene affected the development of the prostate gland and some components of the MAPK pathway.
Animals ; Glycoproteins ; metabolism ; Humans ; MAP Kinase Signaling System ; physiology ; Male ; Prostate ; growth & development ; metabolism ; Protein-Serine-Threonine Kinases ; Proto-Oncogene Proteins ; metabolism ; Proto-Oncogene Proteins c-akt ; Saposins

AIMTo determine the effect of saposin C (a known trophic domain of prosaposin) on proliferation, migration and invasion, as well as its effect on the expression of urokinase plasmonogen activator (uPA), its receptor (uPAR) and matrix metalloproteinases (MMP)-2 and -9 in normal and malignant prostate cells. In addition, we tested whether saposin C can activate p42/44 and stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK) signal transduction pathways of the mitogen-activated protein kinase (MAPK) superfamily.

METHODSWe employed Western blot analysis, phospho-specific antibodies, cell proliferation assay, reverse transcriptase-polymerase chain reaction, in vitro kinase assays and migration and invasion to determine the effect of saposin C on various biological behaviors of prostate stromal and cancer cells.

RESULTSSaposin C, in a cell type-specific manner, upregulates uPA/uPAR and immediate early gene c-Jun expression, stimulates cell proliferation, migration and invasion and activates p42/44 and SAPK/JNK MAPK pathways in prostate stromal and cancer cells. Normal prostate epithelial cells were not responsive to saposin C treatment in the above studies.

CONCLUSIONSaposin C functions as a multipotential modulator of diverse biological activities in prostate cancer and stromal cells. These results strongly suggest that saposin C functions as a potent growth factor for prostatic cells and may contribute to prostate carcinogenesis and/or the development of hormone-refractory prostate cancer.

Cell Division ; drug effects ; Enzyme Activation ; Humans ; Male ; Mitogen-Activated Protein Kinases ; metabolism ; Neoplasm Invasiveness ; Prostatic Neoplasms ; enzymology ; metabolism ; pathology ; Receptors, Cell Surface ; genetics ; Receptors, Urokinase Plasminogen Activator ; Reverse Transcriptase Polymerase Chain Reaction ; Saposins ; pharmacology ; Signal Transduction ; Stromal Cells ; enzymology ; metabolism ; pathology ; Up-Regulation ; Urokinase-Type Plasminogen Activator ; genetics

AIMTo determine the effects of the functional domain of saposin C (neurotrophic peptide [NP]) on androgen receptor (AR) expression and transcriptional activity.

METHODSWe constructed DNA vectors expressing NP or a chimeric peptide of the viral TAT transduction domain and NP (TAT-NP) using gene cloning technology. The effects of ectopic expression of NP or TAT-NP on cell growth were examined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Reverse transcription-polymerase chain reaction (RT-PCR), Western blot, transient transfection and reporter gene assays were used to determine the effects of NP on AR expression and activation.

RESULTSNP stimulated proliferation of androgen responsive LNCaP cells in the absence of androgens. RT-PCR and Western blot analyses showed that ectopic expression of NP resulted in induction of AR gene expression, and that the NP-stimulated expression of AR could be synergistically enhanced in the presence of androgens. Furthermore, reporter gene assay results showed that NP could enhance AR transactivation by increasing androgen-inducible gene reporter activity.

CONCLUSIONWe provided evidence that ectopic expression of saposin C-originated NP could upregulate AR gene expression and activate the AR transcriptional function in an androgen-independent manner in prostate cancer cells.

Cell Division ; Cell Line, Tumor ; DNA, Neoplasm ; genetics ; Gene Expression Regulation, Neoplastic ; Genetic Vectors ; Humans ; Kinetics ; Male ; Nerve Growth Factors ; genetics ; Pancreatic Neoplasms ; genetics ; pathology ; RNA, Messenger ; genetics ; Receptors, Androgen ; genetics ; Restriction Mapping ; Reverse Transcriptase Polymerase Chain Reaction ; Saposins ; metabolism ; Transcription, Genetic ; Up-Regulation