Expression and distribution of cyclooxygenase-2 in human periovulatory ovary

Runt-related transcription factor 1 regulates luteinized hormone-induced prostaglandin-endoperoxide synthase 2 expression in rat periovulatory granulosa cells

Runt-related transcription factor 1 (RUNX1), a transcription factor, is transiently induced by the LH surge and regulates gene expression in periovulatory granulosa cells. Potential binding sites for RUNX are present in the 5'-flanking region of the Ptgs2 (prostaglandin-endoperoxide synthase 2) gene. Periovulatory Ptgs2 expression is essential for ovulation. In the present study, we investigated the role of RUNX1 in mediating the LH-induced expression of Ptgs2 in periovulatory granulosa cells. We first determined whether the suppression of Runx1 expression or activity affects Ptgs2 expression using cultured preovulatory granulosa cells isolated from immature rat ovaries primed with pregnant mare serum gonadotropin for 48 h. Knockdown of human chorionic gonadotropin-induced Runx1 expression by small interfering RNA or inhibition of endogenous RUNX activities by dominant-negative RUNX decreased human chorionic gonadotropin or agonist-stimulated Ptgs2 expression and transcriptional activity of Ptgs2 promoter reporter constructs. Results from chromatin immunoprecipitation assays revealed in vivo binding of endogenous RUNX1 to the Ptgs2 promoter region in rat periovulatory granulosa cells. Direct binding of RUNX1 to two RUNX-binding motifs in the Ptgs2 promoter region was confirmed by EMSA. The mutation of these two binding motifs resulted in decreased transcriptional activity of Ptgs2 promoter reporter constructs in preovulatory granulosa cells. Taken together, these findings provide experimental evidence that the LH-dependent induction of Ptgs2 expression results, in part, from RUNX1-mediated transactivation of the Ptgs2 promoter. The results of the present study assign potential significance for LH-induced RUNX1 in the ovulatory process via regulating Ptgs2 gene expression.

Ovarian epithelial cancer: a role for PGE2-synthesis and signalling in malignant transformation and progression

Background

The involvement of the cyclooxygenases (COX), in particular COX-2, is well documented for many tumours, e.g. colon, breast and prostate cancer, by both experimental and clinical studies. There are epidemiological data from subjects using NSAIDs, and experimental evidence supporting the hypothesis of prostaglandins (PGs) as regulators of tumourigenesis in the ovary. One of the end products of PG-synthesis, PGE₂, regulates several key-processes, which are characteristic for tumour growth, e.g. angiogenesis, proliferation and apoptosisis. The present study investigated the pathway for PGE₂ – synthesis and signalling in ovarian tumourigenesis by analysing specimen from normal ovaries (n = 18), benign (B) (n = 8), borderline type (BL) (n = 6) and malignant tumours (AC) (n = 22). The expression and cell-specific localization of COX-1, COX-2, microsomal prostaglandin E synthase-1 (mPGES-1) and two of the receptors for PGE₂, EP₁ and EP₂, were examined by immunoblotting (IB) and immunohistochemistry (IHC).

Results

The results are in line with earlier studies demonstrating an increase of COX-2 in AC compared to the normal ovary, B and BL tumours. Increased expressions were also observed for COX-1, mPGES-1 and EP-1 which all were significantly (p < 0.05) augmented in less differentiated AC (grades: moderately-, poorly- and undifferentiated). The increase of COX-2 was also correlated to stage (FIGO classification) with significant elevations in stages II and III. EP₁ was increased in stage III while no significant alterations were demonstrated for COX-1, mPGES-1 or EP₂ for stage. IHC revealed staining of the tumour cells, but also increase of COX-1, COX-2, mPGES-1 and EP_1–2 in the stromal compartment of AC (grades: moderately-, poorly- and undifferentiated). This observation suggests interactions between tumour cells and stromal cells (fibroblasts, immune cells), e.g. paracrine signalling mediated by growth factors, cytokines and possibly PGs.

Conclusion

The increases of COX-1, COX-2, mPGES-1 and EP_1–2 in epithelial ovarian cancer, supports the hypothesis that PGE₂-synthesis and signalling are of importance for malignant transformation and progression. The observed augmentations of COX-1, COX-2 and mPGES-1 have implications for future therapeutic strategies.

The human cumulus--oocyte complex gene-expression profile

BACKGROUND

The understanding of the mechanisms regulating human oocyte maturation is still rudimentary. We have identified transcripts differentially expressed between immature and mature oocytes and cumulus cells.

METHODS

Using oligonucleotide microarrays, genome-wide gene expression was studied in pooled immature and mature oocytes or cumulus cells from patients who underwent IVF.

RESULTS

In addition to known genes, such as DAZL, BMP15 or GDF9, oocytes up-regulated 1514 genes. We show that PTTG3 and AURKC are respectively the securin and the Aurora kinase preferentially expressed during oocyte meiosis. Strikingly, oocytes overexpressed previously unreported growth factors such as TNFSF13/APRIL, FGF9, FGF14 and IL4 and transcription factors including OTX2, SOX15 and SOX30. Conversely, cumulus cells, in addition to known genes such as LHCGR or BMPR2, overexpressed cell-to-cell signalling genes including TNFSF11/RANKL, numerous complement components, semaphorins (SEMA3A, SEMA6A and SEMA6D) and CD genes such as CD200. We also identified 52 genes progressively increasing during oocyte maturation, including CDC25A and SOCS7.

CONCLUSION

The identification of genes that were up- and down-regulated during oocyte maturation greatly improves our understanding of oocyte biology and will provide new markers that signal viable and competent oocytes. Furthermore, genes found expressed in cumulus cells are potential markers of granulosa cell tumours.