The molecular mechanism by which sperm triggers Ca 2C oscillation, oocyte activation, and early embryonic development has not been clarified. Recently, oocyte activation has been shown to be induced by sperm-specific phospholipase Cz (PLCz). The ability of PLCz to induce oocyte activation is highly conserved across vertebrates. In the present study, porcine PLCz cDNA was identified and the nucleotide sequence was determined. The expression pattern of porcine PLCz mRNA during the period of postnatal testicular development was shown to be similar to that of mouse PLCz. PLCz mRNA expression in the pig and mouse was detected only in the testes when the elongated spermatids had differentiated, and was detected from day 96 after birth in the pig. Histological examination of porcine testis during the period of postnatal development revealed the presence of spermatozoa from day 110 after birth. These findings suggest that the synthesis of PLCz mRNA starts when spermiogenesis is initiated. Microinjection of porcine PLCz complementary RNA into porcine oocytes demonstrated that porcine PLCz has the ability to trigger repetitive Ca 2C transients in porcine oocytes similar to that observed during fertilization. It was also found that porcine PLCz cRNA has the potential to induce oocyte activation and initiate embryonic development up to the blastocyst stage.

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Context: Asoprisnil, a selective progesterone (P4) receptor (PR) modulator (SPRM) with mixed P4 agonist/antagonist activities, reduces uterine leiomyoma volume in a dose-dependent manner in the presence of follicular phase estrogen concentrations. The evidence from clinical studies suggests that asoprisnil may directly target the uterine leiomyomata. Objective and Methods:The present study evaluated the effects of asoprisnil on cell proliferation, the expression of apoptosis-related proteins, and apoptosis in cultured human uterine leiomyoma cells and matched normal myometrial cells. PR-A and PR-B expression in the two types of cells was comparatively evaluated. Cell proliferation, proliferating cell nuclear antigen (PCNA)-positive rate, and TUNEL-positive rate were assessed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, immunocytochemistry, and terminal deoxynucleotidyl transferase-mediated 2Ј-deoxyuridine 5Ј-triphosphate nick end labeling (TUNEL) assay, respectively. The expression of apoptosis-related proteins and PR was assessed by Western blot analysis. Results:Compared with untreated cultures, asoprisnil decreased the number of viable cultured cells, the PCNA-positive rate, and PCNA protein expression in cultured leiomyoma cells. Asoprisnil increased the TUNEL-positive rate, cleaved caspase-3, and cleaved poly(adenosine 5Ј-diphosphate-ribose) polymerase expression and decreased Bcl-2 protein expression in cultured leiomyoma cells. These effects were dose and time dependent. In cultured myometrial cells, however, asoprisnil did not affect cell proliferation and apoptosis. PR-B expression was elevated in cultured leiomyoma cells compared with cultured myometrial cells, whereas no differences in PR-A expression were noted between the two cell types. Conclusions:These results show that asoprisnil inhibits proliferation and induces apoptosis in cultured uterine leiomyoma cells in the absence of comparable effects on cultured normal myometrial cells, suggesting a cell type-specific effect.

Although the traditional concept supports a crucial role of estrogen in promoting leiomyoma growth, unequivocal evidence has emerged indicating that progesterone also plays a vital role in the regulation of leiomyoma growth. Recent clinical trials have demonstrated the efficacy of asoprisnil, a selective progesterone receptor modulator, and CDB-2914, a novel progesterone receptor modulator, for the treatment of women with symptomatic leiomyomata. These compounds significantly reduced leiomyoma and uterine volume and improved leiomyoma-related symptoms without serious complications. However, the precise mechanism whereby these compounds cause leiomyoma regression remains poorly understood. Our extensive in vitro studies have provided novel evidence for the growth inhibitory effects of asoprisnil and CDB-2914 on cultured leiomyoma cells. Both compounds exhibited antiproliferative, proapoptotic, and antifibrotic actions on cultured leiomyoma cells in the absence of comparable effects on cultured normal myometrial cells. Asoprisnil and/or CDB-2914 modulated the ratio of progesterone receptor isoforms (PR-A and PR-B) in cultured leiomyoma cells; decreased the cell viability; suppressed the expression of growth factors, angiogenic factors, and their receptors in those cells; and induced apoptosis through activating the mitochondrial and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathways and eliciting endoplasmic reticulum stress. Furthermore, these compounds suppressed types I and III collagen synthesis by modulating extracellular matrix-remodeling enzymes in cultured leiomyoma cells without affecting those syntheses in cultured normal myometrial cells. These findings indicate that both compounds exert antiproliferative, proapoptotic, and antifibrotic actions on leiomyoma cells in a cell-type specific manner. This supports the notion that asoprisnil and CDB-2914 hold promise for the nonsurgical treatment of uterine leiomyomata.