STUDY QUESTION
What are the roles of the microRNA miR-210—an miRNA that is up-regulated in endometriotic cyst stromal cells (ECSCs)—in the pathogenesis of endometriosis?
SUMMARY ANSWER
Up-regulated ...miR-210 expression in ECSCs is involved in their proliferation, resistance to apoptosis and angiogenesis through signal transducer and activator of transcription (STAT) 3.
WHAT IS KNOWN ALREADY
In the pathogenesis of endometriosis, a number of roles for microRNAs (miRNAs) are becoming apparent.
STUDY DESIGN, SIZE, DURATION
ECSCs and normal endometrial stromal cells (NESCs) were isolated from ovarian endometriotic tissues (patients aged 24–40 years undergoing salpingo-oophorectomy or evisceration for the treatment of ovarian endometriotic cysts, n = 10) and the eutopic endometrial tissues without endometriosis (premenopausal patients aged 35–45 years undergoing hysterectomies for subserousal leiomyoma, n = 13), respectively.
PARTICIPANTS/MATERIALS, SETTING, METHODS
We used a global gene expression microarray technique to identify downstream targets of miR-210, and we assessed the functions of miR-210 in the pathogenesis of endometriosis by using the miR-210-transfected NESCs.
MAIN RESULTS AND THE ROLE OF CHANCE
Gene expression microarray analysis revealed that one of the key target molecules of miR-210 is STAT3. In the NESCs, in comparison to the control, miR-210 transfection resulted in the induction of cell proliferation (P < 0.0005), the production of vascular endothelial cell growth factor (VEGF) (P < 0.0005) and the inhibition of apoptosis (P < 0.05) through STAT3 activation increased levels of mRNA (P < 0.0005), and protein (P < 0.005). In the ECSCs, inhibitors of STAT3 inhibited the cell proliferation and VEGF production (P < 0.05), and induced the apoptosis of these cells (P < 0.05).
LIMITATIONS, REASONS FOR CAUTION
The roles of aberrant miR-210 expression were investigated only in the stromal component of ectopic and eutopic endometrium. Control endometrial tissues were obtained from premenopausal patients who had subserosal leiomyoma and NESC gene expression patterns may be altered in these women. Furthermore, the effects of STAT3 inhibitors were evaluated only in ECSCs and not in NESCs.
WIDER IMPLICATIONS OF THE FINDINGS
The present findings indicate that miR-210 induces NESCs to differentiate into the endometriotic phenotype and we speculate that up-regulated miR-210 expression in ECSCs is involved in the creation of the endometriosis-specific cellular dysfunctions through epigenetic mechanisms. The data indicate that STAT3 inhibitors may be promising candidates for the treatment of endometriosis.
STUDY FUNDING/COMPETING INTEREST(S)
This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (no. 13237327 to K.N., no. 25861500 to Y.K. and no. 23592407 to H.N.). There are no conflicts of interest to declare.
STUDY QUESTION
What is the global expression pattern of microRNAs (miRNAs) in endometriotic stromal cells and is miR-196b involved in the pathogenesis of endometriosis?
SUMMARY ANSWER
Several miRNAs ...are aberrantly expressed in endometriotic cyst stromal cells (ECSCs), including miR-196b whose expression is repressed in endometriotic stromal cells.
WHAT IS KNOWN ALREADY
Although, histologically, endometriotic tissues and normal proliferative endometrium are similar, a number of distinct molecular differences have been reported to date. The anti-apoptotic and excessive proliferative properties of endometriotic cells are considered to be involved in the development and progression of endometriosis.
STUDY DESIGN AND SIZE DURATION
ECSCs and normal endometrial stromal cells (NESCs) were isolated from ovarian endometriotic tissues and eutopic endometrial tissues, respectively and compared.
PARTICIPANTS/MATERIALS, SETTING AND METHODS
Aberrantly expressed miRNAs in ECSCs were identified by a global miRNA microarray technique. The roles of miR-196b in ECSC proliferation, apoptosis, and c-myc and B-cell lymphoma/leukemia (Bcl)-2 mRNA expression were investigated with precursor hsa-miR-196b transfection. The methylation status of the miR-196b gene in ECSCs and the effect of a DNA demethylating agent on miR-196b expression were also examined.
MAIN RESULTS AND THE ROLE OF CHANCE
miRNA microarray analysis identified eight down-regulated miRNAs (including miR-196b) and four up-regulated miRNAs in ECSCs. Compulsory expression of miR-196b directed the inhibition of proliferation and the induction of apoptosis in ECSCs. miR-196b was found to suppress c-myc and Bcl-2 mRNA expression in ECSCs, and there was a significant correlation between miR-196b and HOXA10 expression in ECSCs and NESCs. The miR-196b gene was hypermethylated in ECSCs when compared with NESCs, and the treatment with a DNA demethylating agent restored the expression of miR-196b in ECSCs.
LIMITATIONS AND REASONS FOR CAUTION
miRNA expression profiles were investigated only in the stromal component of ectopic and eutopic endometrium samples. In addition to miR-196b, the roles of other miRNAs aberrantly expressed in ECSCs should be examined.
WIDER IMPLICATIONS OF THE FINDINGS
The present findings suggest that aberrant miRNA expression plays an important role in the pathogenesis of endometriosis as a part of epigenetic mechanisms, that expression of miR-196b in ECSCs is repressed by DNA hypermethylation of the miR-196b gene and this repression may be involved in the development of proliferative and anti-apoptotic characteristics of endometriosis.
STUDY FUNDING
This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (no. 20591920 to K.N. and no. 23592407 to H.N.) and The Uehara Memorial Foundation (to K.N.).
BACKGROUND
Accumulating evidence suggests that various epigenetic aberrations play definite roles in the pathogenesis of endometriosis. We investigated the histone acetylation status in endometriosis ...and the application of the histone deacetylase inhibitors (HDACIs) for the treatment of endometriosis.
METHODS
The levels of acetylated histones in the endometriotic cyst stromal cells (ECSCs) and normal endometrial stromal cells (NESCs) were evaluated. The effects of the HDACIs on cell proliferation, the cell cycle, apoptosis of ECSCs and NESCs, and the expression of genes related to these cellular events were investigated. The effects of HDACIs on histone acetylation in chromatin of the promoter region of the cell cycle regulatory genes in ECSCs were also investigated.
RESULTS
The acetylated histone levels were significantly lower in ECSCs than in NESCs (P < 0.025). HDACIs inhibited cell proliferation and induced cell cycle arrest and apoptosis of ECSCs. The effects of HDACIs on NESCs were marginal or weak. These HDACIs induced an accumulation of acetylated histones in total cellular chromatin and in the promoter regions of the p16INK4a, p21Waf1/Cip1, p27Kip1 and cycle checkpoint kinase 2 genes in ECSCs. HDACIs induced the protein expression of these cell cycle regulators and suppressed the protein expression of Bcl-2 and Bcl-XL in ECSCs.
CONCLUSIONS
The present findings demonstrated that aberrant histone modifications are present in endometriosis and that HDACIs reactivated epigenetically silenced genes, resulting in the suppression of cell proliferation, induction of cell cycle arrest and apoptosis of ECSCs. HDACIs are therefore promising agents for the treatment of endometriosis.
BACKGROUND Controversy has arisen on the natural history of early gastric cancer (EGC). While some emphasise the effectiveness of early detection in reducing mortality from gastric cancer, others ...insist that EGC is a pseudo-cancer. AIMS/PATIENTS/METHODS To elucidate the natural history of EGC, a non-concurrent, long term, follow up study was conducted in 71 patients who were diagnosed endoscopically as having EGC, which was confirmed as cancer on biopsy, but in whom surgical resection was not conducted or delayed by more than six months. RESULTS The natural course of EGC was observed in 56 cases. Over a period of 6–137 months, 20 remained in the early stage while 36 progressed to the advanced stage. The proportion remaining in the early stage consistently decreased with time. Median duration of those who remained in the early stage was estimated as 44 months. The cumulative five year risk for progressing to the advanced stage was 63.0%. In 38 cases there was no evidence for undergoing surgical resection for gastric cancer. The cumulative five year corrected survival was estimated as 62.8% among those unresected. Hazard rate ratio for gastric cancer mortality was 0.65 (p=0.34) for screening detected versus non-screening detected. Hazard rate ratio for gastric cancer mortality was 0.51, significantly lower for patients whose operations were delayed compared with those unresected. CONCLUSIONS Although EGC showed a relatively long natural history in general, it progressed to the advanced stage with time and led to death from gastric cancer for the most part if left untreated.
BACKGROUND
In order to investigate the regulation of chemokines interleukin-8 (IL-8), growth-regulated oncogene (GRO)α, monocyte chemoattractant protein-1 (MCP-1)) induced by thrombin in endometrial ...stromal cells (ESCs), the effects of thrombin, a protease activated receptor (PAR)-1 antagonist (PPACK), mitogen-activated protein kinase kinase inhibitor (U0126), phospholipase C inhibitor (U-73122), an antagonist of the intracellular InsP3 receptor (2-aminoethoxy-diphenylborate (2-APB) and a protein kinase C inhibitor (GF-109203X) on the production of chemokines by ESCs were evaluated.
METHODS
ESCs from eight endometrial specimens in the secretory phase were cultured and incubated for 24h with thrombin and PPACK, U0126, U-73122, 2-APB or GF-109203X. The levels of IL-8, GROα and MCP-1 in the culture medium were measured by means of ELISA. The activation of MAP kinase was detected by western blot analysis using anti-phosphorylated MAP kinase (ERK1/2) antibody.
RESULTS
Following stimulation by thrombin, the production of IL-8, GROα and MCP-1 increased significantly in a dose-dependent manner. PPACK, U0126, U-73122, 2-APB or GF-109203X suppressed the increases in production of IL-8, GROα and MCP-1 induced by thrombin (P < 0.001, P <0.001 and P <0.001, respectively). MAP kinase activities were induced by treatment with thrombin, and were suppressed by PPACK, U0126, U-73122, 2-APB or GF-109203X.
CONCLUSIONS
Our results suggest that thrombin stimulates the production of IL-8, GROα and MCP-1 via PAR-1 by a mechanism involving the MAP kinase system. The increases in IL-8, GROα and MCP-1 may contribute to the maintenance of implantation involving leukocyte chemotaxis.
Endometriosis, a disease affecting 3-10% of women of reproductive age, is characterized by the ectopic growth of endometrial tissue. Increasingly, endometriosis is also becoming recognized as a ...condition in which ectopic endometrial cells exhibit abnormal proliferative and apoptotic regulation in response to appropriate stimuli. Apoptosis plays a critical role in maintaining tissue homeostasis and represents a normal function to eliminate excess or dysfunctional cells. Accumulated evidence suggests that, in healthy women, endometrial cells expelled during menstruation do not survive in ectopic locations because of programmed cell death, while decreased apoptosis may lead to the ectopic survival and implantation of these cells, resulting in the development of endometriosis. Both the inability of endometrial cells to transmit a 'death' signal and the ability of endometrial cells to avoid cell death have been associated with increased expression of anti-apoptotic factors and decreased expression of pre-apoptotic factors. This paper is a review of the recent literature focused on the differential expression of apoptosis-associated molecules in the normal endometria of women without endometriosis, and in the eutopic and ectopic endometria of women with endometriosis. The role of apoptosis in the pathogenesis of endometriosis and the basic and clinical research on the current medical treatment for endometriosis from the view of apoptosis will be discussed.
PDF
