Expression of alpha6 and beta4 integrin subunits on human endometrium throughout the menstrual cycle and during early pregnancy

Pregnancy and Cancer: Cellular Biology and Mechanisms Affecting the Placenta

Cancer during pregnancy is rarely studied due to its low incidence (1:1000). However, as a result of different sociocultural and economic changes, women are postponing pregnancy, so the number of pregnant women with cancer has been increasing in recent years. The importance of studying cancer during pregnancy is not only based on maternal and foetal prognosis, but also on the evolutionary mechanisms of the cell biology of trophoblasts and neoplastic cells, which point out similarities between and suggest new fields for the study of cancer. Moreover, the magnitude of how cancer factors can affect trophoblastic cells, and vice versa, in altering the foetus's nutrition and health is still a subject to be understood. In this context, the objective of this narrative review was to show that some researchers point out the importance of supplementing branched-chain amino acids, especially leucine, in experimental models of pregnancy associated with women with cancer. A leucine-rich diet may be an interesting strategy to preserve physiological placenta metabolism for protecting the mother and foetus from the harmful effects of cancer during pregnancy.

The Depolarized Expression of the Alpha-6 Integrin Subunit in the Endometria of Women With Endometriosis

OBJECTIVE

The current study sought to compare the endometrial localization of the integrin subunit alpha-6 in women with endometriosis and women without the disease. Alpha-6 integrins have an important function, not only in the attachment of cells to the extracellular matrix and laminin, but they also serve as inductors of cell migration and invasion, depending on their pattern of expression in the cell membrane.

METHODS

The endometriosis group consisted of 32 women with a confirmed diagnosis of endometriosis by laparoscopy or laparotomy. The control group consisted of 20 women not having endometriosis or any other gynecologic disease at laparoscopy. Endometria were obtained by biopsy. Immunohistochemical techniques were used to assess alpha-6 localization. In each section, the percentage of positive cells and the localization of expression were evaluated.

RESULTS

All glandular cells expressed alpha-6 in all of the samples but presented two different patterns, either only in the basal side of the cells (polarized) or also in other sides of the cells (depolarized). The percentage of samples showing depolarized expression was significantly higher in the endometriosis group (66.6% vs 15.8%, chi2 =12.09, P = .001).

CONCLUSIONS

The endometria of women with endometriosis more frequently show a depolarized expression of integrin subunit alpha-6, a characteristic usually found in highly proliferating cells with migrating and invasive abilities.

Endometrial gene expression in high- and low-fertility heifers in the late luteal phase of the estrous cycle and a comparison with midluteal gene expression

Embryonic mortality is a major constraint to improving reproductive efficiency and profitability in livestock enterprises. We previously reported differential expression of genes with identified roles in cellular growth and proliferation, lipid metabolism, endometrial remodeling, inflammation, angiogenesis, and metabolic exchange in endometrial tissue on day 7 of the estrous cycle (D7), between heifers ranked as either high (HF) or low (LF) for fertility. The aim of the current study was to further elucidate the underlying molecular mechanisms contributing to early embryo loss by examining differential endometrial gene expression in HF or LF heifers at a later stage of the estrous cycle;day 14(D14). A second objective was to compare these expression profiles with those from midluteal HF and LF endometrium. Using the same animal model as employed in the previous study, we slaughtered HF and LF animals on D14, harvested endometrial tissue, and carried out global gene expression analysis using the Affymetrix Bovine GeneChip. Microarray analysis detected 430 differentially expressed genes (DEG) between HF and LF animals. Ingenuity Pathway Analysis revealed enrichment for a host of biological pathways including lipid metabolism, molecular transport, immune response, cell morphology and development, and cell growth and proliferation. Important DEG includedALB, BMPR2, CCL28, COL4A3/4, FADS1, ITGA6, LDLR, PLCB3, PPARG, PTGS2, and SLC27A4 Furthermore, DEG expressed on both D7 and D14 included:PCCB,SLC25A24,DAP, and COL4A4 This study highlights some of the pathways and mechanisms underpinning late luteal bovine endometrial physiology and endometrial-related conception rate variance.

Bovine pretransfer endometrium and embryo transcriptome fingerprints as predictors of pregnancy success after embryo transfer

Aberrant gene expression in the uterine endometrium and embryo has been the major causes of pregnancy failure in cattle. However, selecting cows having adequate endometrial receptivity and embryos of better developmental competence based on the gene expression pattern has been a greater challenge. To investigate whether pretransfer endometrial and embryo gene expression pattern has a direct relation with upcoming pregnancy success, we performed a global endometrial and embryo transcriptome analysis using endometrial and embryo biopsy technology and the pregnancy outcome information. For this, endometrial samples were collected from Simmental heifers at day 7 and 14 of the estrous cycle, one cycle prior to embryo transfer. In the next cycle, blastocyst stage embryos were transferred to recipients at day 7 of the estrous cycle after taking 30-40% of the blastocyst as a biopsy for transcriptome analysis. The results revealed that at day 7 of the estrous cycle, the endometrial gene expression pattern of heifers whose pregnancy resulting in calf delivery was significantly different compared with those resulting in no pregnancy. These differences were accompanied by qualitative and quantitative alteration of major biological process and molecular pathways. However, the transcriptome difference was minimal between the two groups of animals at day 14 of the estrous cycle. Similarly, the transcriptome analysis between embryos biopsies that resulted in calf delivery and those resulted in no pregnancy revealed a total of 70 differentially expressed genes. Among these, the transcript levels of 32 genes including SPAG17, PF6, UBE2D3P, DFNB31, AMD1, DTNBP1, and ARL8B were higher in embryo biopsies resulting in calf delivery. Therefore, the present study highlights the potential of pretransfer endometrial and embryo gene expression patterns as predictors of pregnancy success in cattle.

Microarray evaluation of endometrial receptivity in Chinese women with polycystic ovary syndrome

Patients with polycystic ovary syndrome (PCOS) have lower pregnancy and higher miscarriage rates, possibly due to decreased endometrial receptivity. In this study, endometrium was processed for RNA extraction and hybridization of chemically fragmented, biotinylated, complementary RNA on high-density oligonucleotide microarrays, and screened for 21,571 genes. Real-time polymerase chain reaction (PCR) was used to verify the result. Genes found to be down-regulated in the endometrium during the implantation window in PCOS patients included those whose activity was integral to membrane function, adhesion, invasive growth and the cytoskeleton. Among these genes, some have previously been associated with endometrial receptivity (by microarray research or other methods) and some have never previously been associated with endometrial receptivity. Using real-time PCR, expression of transmembrane 4 superfamily member 4 (TM4SF4) and matrix metalloproteinase 26 (MMP26) was found to be significantly decreased during the implantation window in patients with PCOS (P= 0.003). TM4SF4 has been demonstrated to be associated with adhesion; MMP26 has been shown to be related to degradation of extracellular matrix. It is suggested the down-regulated gene expression during the implantation window in patients with PCOS indicates differential gene expression in the endometrium between PCOS and normal women during the implantation window. This might affect endometrial receptivity.

Immunohistochemical localization of beta1 and beta4 integrins in mouse endometrium during implantation and early pregnancy

Implantation presents the remarkable synchronisation between the development of embryo and differentiation of endometrium. Cell-cell adhesion is an important phenomenon taking place during blastocyst implantation in uterine membrane. We think that the investigation of existence and the level of integrins in women can be a guide for treatment of infertility. Our purpose in this study was to show expression beta1 and beta4 integrins on gestational days 4, 6, 12 by immunohistochemical methods and to investigate whether beta4 integrin is a useful marker for receptivity. beta1 and beta4 integrin were exhibited on surface epithelium on gestational day 4. On the other hand, strong beta4 immunoreactivity was detected on surface epithelium and glandular cells on gestational day 12 but no beta1 reactivity was present in the surface epithelium and glandular cells on day 12. In conclusion, both beta1 and beta4 integrins may have a role in implantation process because positive immunoreactivity was seen on apical membrane of surface epithelium on day 4 when implantation occurred. The localization to apical pole of surface epithelium suggest a role for beta1, beta4 integrins in initial embryo and endometrium interaction. It does not seem that beta1 integrin has a role supporting pregnancy since expression of beta4 on surface epithelium and glandular epithelium disappeared on day 12. beta4 integrin expression increasing on day 12 of pregnancy leads us to think a possible functional role supporting pregnancy.

Expression of integrin alpha5 and integrin beta4 and their extracellular ligands fibronectin and laminin in human decidua during early pregnancy and its sex steroid-mediated regulation

The reorganization of the human endometrium is termed decidualization, which includes endometrial cell proliferation, differentiation, integrin switching and extracellular matrix (ECM) remodeling during early pregnancy. The present study aimed to investigate distribution patterns, staining intensity and sex steroid-mediated regulation of integrin alpha5 (CD49e), integrin beta4 (CD49f) expression and their ligands fibronectin and laminin during decidualization. Human tissue samples were evaluated in two groups, those collected in early days and those collected in advanced days of the first trimester. Correlating immunostaining was found between laminin and integrin beta4, and between fibronectin and integrin alpha5. The expression of fibronectin was higher than that of laminin in the early days (p < 0.05). Temporal and spatial immunostaining of integrin beta4 and alpha5 in the apical pole of luminal and glandular cells was observed as pregnancy progressed (p < 0.05). In vitro results showed that human chorionic gonadotropin (hCG) stimulated laminin expression, downregulated integrin beta4 expression, whereas estradiol decreased fibronectin expression by Ishikawa cells. hCG suppressed fibronectin expression in endometrial stromal cells in culture. Our results suggest that fibronectin is responsible for induction of decidual cell differentiation, and different temporal and spatial expression of the integrins may play a role in implantation. Our in vitro results suggest that regulation of extracellular matrix remodeling and integrin switching are at least partially regulated by reproductive hormones.

Endometrial receptivity and the window of implantation

Implantation is a highly co-ordinated event that involves both embryonic and endometrial participation. The endometrium expresses a sophisticated repertoire of proteins during the menstrual cycle many of which help to define a period of receptivity collectively known as the 'window of implantation'. Many of these factors, which are temporally aligned with this window, are now seen as chemical messengers that are recognized by the embryo and facilitate embryonic growth and differentiation. The use of such proteins as biomarkers has also advanced our understanding of the implantation process and may identify women with implantation failure and infertility. While the study of endometrial receptivity is still evolving, the field is growing rapidly and will probably enhance our ability to diagnose and treat couples with infertility, especially in the arena of assisted reproductive technologies (ART).

A quantitative evaluation of alpha1, alpha4, alphaV and beta3 endometrial integrins of fertile and unexplained infertile women during the menstrual cycle. A flow cytometric appraisal

The expression of integrin molecules alpha1beta1, alpha4beta1 and alphaVbeta3 within endometrial tissue has been proposed as a marker of uterine receptivity during the implantation window. The present investigation examines by flow cytometric analysis the concentrations of alpha1, alpha4, alphaV and beta3 integrin subunits in endometrial stromal (ESC) and epithelial cells (EEC) in two groups of women throughout the menstrual cycle: normal fertile women (n = 27) and women with unexplained infertility (n = 26). Integrin concentrations in endometrial cells were calculated in relative fluorescence units against a negative cellular control. The assessment of integrin subunits detected the protein in ESC and EEC from the late proliferative to the late secretory phase. In both groups of women, the alpha1 was the highest integrin expressed in ESC and EEC throughout the menstrual cycle. All women exhibited low concentrations of alpha4-EEC at the time of the implantation window. Infertile women expressed lower concentrations of the alpha4-ESC during the proliferative and early secretory phase while lower concentrations of the alpha1-ESC were seen during the late secretory phase. Interestingly, the infertile women expressed lower concentrations of beta3-EEC in the early, mid-secretory and late secretory phases (P < 0.05). Infertile women also expressed lower concentrations of alpha1-EEC and alphaV-EEC during the late secretory phase (P < 0.05). It can be concluded that the quantitative determination of beta3-EEC by flow cytometry confirmed its potential feature as a marker of endometrial receptivity at the time of the implantation window. In addition, the defective expression of the alpha1-ESC found in the late secretory phase might be associated with the poor fertility outcome of women with unexplained infertility.

Expression of alpha6 and beta4 integrin subunits throughout the menstrual cycle: no correlation with uterine receptivity

OBJECTIVE

To compare the expression of alpha6 and beta4 integrin subunit levels throughout the menstrual cycle in the endometrium of healthy women and infertile women.

DESIGN

Prospective study.

SETTING

An academic teaching hospital.

PATIENT(S)

Endometrium was collected from 58 women, including healthy subjects (n = 28) and patients undergoing diagnostic testing for infertility (n = 30).

INTERVENTION(S)

Endometrial biopsies were performed throughout the menstrual cycle in healthy women and infertile women.

MAIN OUTCOME MEASURE(S)

Immunohistochemical staining intensity of alpha6 and beta4 using the semiquantitative immunohistochemical score, compared using regression analysis and analysis of variance with Scheffé's correction.

RESULT(S)

There was no correlation between menstrual cycle phase and endometrial integrin subunit alpha6 or beta4 on glandular or luminal epithelium. Even women with identified luteal phase defects had indistinguishable patterns of expression for these integrin subunits during the window of implantation.

CONCLUSION(S)

The integrin subunits alpha6 and beta4 are expressed uniformly throughout the menstrual cycle on glandular and luminal epithelium. These integrins may have a housekeeping role in anchoring endometrial epithelium and do not appear to be useful markers of uterine receptivity.

Expression of integrin messenger ribonucleic acid in human endometrium: a quantitative reverse transcription polymerase chain reaction study

OBJECTIVE

To assess the expression of selected integrin subunit's messenger RNA (mRNA) in human endometrium during the menstrual cycle.

DESIGN

A prospective comparative study.

SETTING

Academic research environment.

PATIENT(S)

Premenopausal women with histologically normal endometrium who were undergoing hysterectomy.

INTERVENTION(S)

Endometrial tissues were collected.

RESULT(S)

Human endometrium expresses integrins alpha2, alpha3, alpha4, alpha5, alpha6.1, alpha6.2, alpha v, beta1, beta2, beta3, and beta5, as well as fibronectin mRNA. The levels of endometrial integrins mRNA expression varied significantly, with the lowest levels observed for alpha2, beta3, and fibronectin and the highest for alpha5, beta2, and beta5. The levels of integrins alpha2, alpha3, and alpha5 mRNA expression were significantly higher during the proliferative phase, whereas alpha4, alpha6.2, alpha v, beta1, beta2, beta3, beta5, and fibronectin were higher during the secretory phase of the menstrual cycle. The alpha6.1 mRNA was found to be equally expressed in the endometrium during the menstrual cycle, whereas the most dramatic changes occurred in alpha v and beta3 expression, compared with other integrin subunits.

CONCLUSION(S)

Human endometrium expresses mRNA for several integrins and fibronectin, with up-regulation of alpha4, alpha v, beta1, and beta3 during the secretory phase of the menstrual cycle, suggesting that their differential expression may be regulated in part by ovarian steroids.