Investigation of hypoxia networks in ovarian cancer via bioinformatics analysis.

BACKGROUND: Ovarian cancer is a leading cause of the death from gynecologic malignancies. Hypoxia is closely related to the malignant growth of cells. However, the molecular mechanism of hypoxia-regulated ovarian cancer cells remains unclear. Thus, this study was conducted to identify the key genes and pathways implicated in the regulation of hypoxia by bioinformatics analysis. METHODS: Using the datasets of GSE53012 downloaded from the Gene Expression Omnibus (GEO), the differentially expressed genes (DEGs) were screened by comparing the RNA expression from cycling hypoxia group, chronic hypoxia group, and control group. Subsequently, cluster analysis was performed followed by the construction of the protein-protein interaction (PPI) network of the overlapping DEGs between the cycling hypoxia and chronic hypoxia using ClusterONE. In addition, gene ontology (GO) functional and pathway enrichment analyses of the DEGs in the most remarkable module were performed using Database for Annotation, Visualization and Integrated Discovery (DAVID) software. Ultimately, the signaling pathways associated with hypoxia were verified by RT-PCR, WB, and MTT assays. RESULTS: A total of 931 overlapping DEGs were identified. Nine hub genes and seven node genes were screened by analyzing the PPI and pathway integration networks, including ESR1, MMP2, ErbB2, MYC, VIM, CYBB, EDN1, SERPINE1, and PDK. Additionally, 11 key pathways closely associated with hypoxia were identified, including focal adhesion, ErbB signaling, and proteoglycans in cancer, among which the ErbB signaling pathway was verified by RT-PCR, WB, and MTT assays. Furthermore, functional enrichment analysis revealed that these genes were mainly involved in the proliferation of ovarian cancer cells, such as regulation of cell proliferation, cell adhesion, positive regulation of cell migration, focal adhesion, and extracellular matrix binding. CONCLUSION: The results show that hypoxia can promote the proliferation of ovarian cancer cells by affecting the invasion and adhesion functions through the dysregulation of ErbB signaling, which may be governed by the HIF-1α-TGFA-EGFR-ErbB2-MYC axis. These findings will contribute to the identification of new targets for the diagnosis and treatment of ovarian cancer.

Reproductive role of miRNA in the hypothalamic-pituitary axis.

The hypothalamic-pituitary-gonadal (HPG) axis plays a critical role in regulating reproductive function. Gonadotropin-releasing hormone (GnRH), which is secreted by the hypothalamus, acts on pituitary gonadotrophs to stimulate luteinizing hormone (LH) and follicle-stimulating hormone (FSH) synthesis and secretion, ultimately affecting the animal's fertility. MicroRNAs are small, non-coding RNAs that are widely expressed throughout the brain and can fine-tune gene expression post-transcriptionally. Recently, growing evidence has unveiled the central position of miRNAs within a key regulatory process involving GnRH secretion and subsequent activation in the pituitary. Although transcriptional regulation of reproduction has been well studied, the post-transcriptional processes are less well understood. In this review, we elaborate comprehensively on the critical role of miRNAs in the reproductive process, including both temporal and spatial aspects. A better understanding of how miRNAs impact the neuroendocrine system may improve our knowledge of reproduction and provide novel targets for therapeutic development.

The potential regulatory mechanisms of the gonadotropin-releasing hormone in gonadotropin transcriptions identified with bioinformatics analyses.

BACKGROUND: The regulation of gonadotropin synthesis and release by gonadotropin-releasing hormone (GnRH) plays an essential role in the neuroendocrine control of reproduction. However, the mechanisms underlying gonadotropin regulation by GnRH pulse frequency and amplitude are still ambiguous. This study aimed to explore the molecular mechanisms and biological pathways associated with gonadotropin synthesis by GnRH pulse frequencies and amplitudes. METHODS: Using GSE63251 datasets downloaded from the Gene Expression Omnibus (GEO), differentially expressed genes (DEGs) were screened by comparing the RNA expression from the GnRH pulse group, the GnRH tonic group and the control group. Pathway enrichment analyses of DEGs was performed, followed by protein-protein interaction (PPI) network construction. Furthermore, sub-network modules were constructed by ClusterONE and GO function and pathways analysed by DAVID. In addition, the relationship between the metabolic pathways and the GnRH pathway was verified in vitro. RESULTS: In total, 531 common DEGs were identified in GnRH groups, including 290 up-regulated and 241 down-regulated genes. DEGs predominantly enriched in 16 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including 11 up-regulated pathways (signallingsignallingmetabolic pathways, signallingand GnRH signalling pathway) and 5 down-regulated pathways (type II diabetes mellitus). Moreover, FBJ osteosarcoma oncogene (FOS) and jun proto-oncogene (JUN) had higher connectivity degrees in the PPI network. Three modules in the PPI were identified with ClusterONE. The genes in module 1 were significantly enriched in five pathways, including signallingthe insulin resistance and GnRH signalling pathway. The genes in modules 2 and 3 were mainly enriched in metabolic pathways and steroid hormone biosynthesis, respectively. Finally, knockdown leptin receptor (LEPR) and insulin receptor (INSR) reversed the GnRH-modulated metabolic related-gene expression. CONCLUSIONS: The present study revealed the involvement of GnRH in the regulation of gonadotropin biosynthesis and metabolism in the maintenance of reproduction, achieved by bioinformatics analyses. This, indicates that the GnRH signalling pathway played a central linkings role in reproductive function and metabolic balance. In addition, the present study identified the difference response between GnRH pulse and GnRH tone, indicated that abnormal GnRH pulse and amplitude may cause disease, which may provide an improved understanding of the GnRH pathway and a new insight for disease diagnosis and treatment.

MicroRNA Mediating Networks in Granulosa Cells Associated with Ovarian Follicular Development.

Ovaries, which provide a place for follicular development and oocyte maturation, are important organs in female mammals. Follicular development is complicated physiological progress mediated by various regulatory factors including microRNAs (miRNAs). To demonstrate the role of miRNAs in follicular development, this study analyzed the expression patterns of miRNAs in granulosa cells through investigating three previous datasets generated by Illumina miRNA deep sequencing. Furthermore, via bioinformatic analyses, we dissected the associated functional networks of the observed significant miRNAs, in terms of interacting with signal pathways and transcription factors. During the growth and selection of dominant follicles, 15 dysregulated miRNAs and 139 associated pathways were screened out. In comparison of different styles of follicles, 7 commonly abundant miRNAs and 195 pathways, as well as 10 differentially expressed miRNAs and 117 pathways in dominant follicles in comparison with subordinate follicles, were collected. Furthermore, SMAD2 was identified as a hub factor in regulating follicular development. The regulation of miR-26a/b on smad2 messenger RNA has been further testified by real time PCR. In conclusion, we established functional networks which play critical roles in follicular development including pivotal miRNAs, pathways, and transcription factors, which contributed to the further investigation about miRNAs associated with mammalian follicular development.

Application of epigenetic markers in molecular breeding of the swine.

Livestock phenotypes are determined by the interaction of a variety of factors, including the genome, the epigenome and the environment. Epigenetics refers to gene expression changes without DNA sequence alterations. Epigenetic markers mainly include DNA methylation, histone modifications, non-coding RNAs, and imprinting genes. More and more researches show that epigenetic markers play an important role in the traits of pigs by modulating phenotype changes via gene expression. However, the role of epigenetic markers has caught little attention in swine breeding. The mechanism that influences important traits of swine has not been analyzed in detail, and it still lacks adequate scientific basis for practical applications. From the aspects of nutrition, diseases, important economic traits and trans-generational inheritance, we summarize the research, application prospects and challenges in the field of utilizing epigenetic markers in molecular breeding of pigs, thus providing a more comprehensive theoretical basis to promote more rapid research development in this field.

[A mechanistic review of how hypoxic mircroenvironment regulates mammalian ovulation].

Mammalian ovulation is a complicated process that includes development of follicles, ovulation, formation of corpus luteum and luteolysis. The three different stages of the ovulation activity are affected by hypoxic microenvironment and hypoxia-induced factors (HIF), which play a crucial role in physiologyical processes, such as angiogenesis and inflammation. Although the process of ovulation has been well elucidated, the molecular mechanism regulated by hypoxia needs an in depth study. In this review, we summarize how hypoxic and HIF regulate gene expression during mammalian ovulation in order to provide a better understanding of ovulation mechanism, which may lay a theoretical basis for prevention and therapy of various ovarian diseases.

[The mechanism of miRNA-mediated PGR signaling pathway in regulating female reproduction].

MicroRNAs (miRNAs) are involved in several physiological processes as important post-transcriptional regulators. Progesterone (P4), an important steroid hormone, produces physiological effect through binding specific receptor progesterone receptors (PGR) which regulates functions of both reproductive and non-reproductive tissues as a member of the nuclear receptor superfamily. P4/PGR and miRNAs could regulate female reproduction independently, however, it is still unclear how miRNAs and P4/PGR interaction regulates female reproductive activities such as ovulation in female reproduction. In this review, we summarize the possible ways in which miRNAs regulate P4 production and PGR gene expression as well as P4/PGR regulate miRNAs expression, which provide a theoretical basis for further studying the role of miRNAs and P4/PGR in female reproduction.