Menstrual cycle dependent expression of CD44 in normal human endometrium

Differential expression of Oct-4, CD44, and E-cadherin in eutopic and ectopic endometrium in ovarian endometriomas and their correlations with clinicopathological variables

BACKGROUND

Endometriosis is an estrogen-dependent inflammatory disease that often causes infertility and chronic pelvic pain. Although endometriosis is known as a benign disease, it has demonstrated characteristics of malignant neoplasms, including neoangiogenesis, tissue invasion, and cell implantation to distant organs. Octamer-binding protein 4 (Oct-4) is a molecular marker for stem cells that plays an essential role in maintaining pluripotency and self-renewal processes in various types of benign and malignant tissues. CD44 is a multifunctional cell surface adhesion molecule that acts as an integral cell membrane protein and plays a role in cell-cell and cell-matrix interactions. E-cadherin is an epithelial cell-cell adhesion molecule that plays important role in the modulation of cell polarization, cell migration, and cancer metastasis. The aim of this study was to investigate the expression patterns of Oct-4, CD44, and E-cadherin in eutopic and ectopic endometrial tissues from women with endometrioma compared to control endometrial tissues from women without endometrioma.

METHODS

In the present study, Oct-4, CD44, and E-cadherin expressions were evaluated in eutopic and ectopic endometrial tissue samples from women with endometrioma (n = 32) and compared with those of control endometrial tissue samples from women without endometrioma (n = 30).

RESULTS

Immunohistochemical expression of Oct-4 was significantly higher in the ectopic endometrial tissue samples of women with endometrioma than in the control endometrial tissue samples (p = 0.0002). Conversely, CD44 and E-cadherin expressions were significantly lower in the ectopic endometrial tissue samples of women with endometrioma than in the control endometrial tissue samples (p = 0.0137 and p = 0.0060, respectively). Correlation analysis demonstrated significant correlations between Oct-4 expression and endometrioma cyst diameter (p = 0.0162), rASRM stage (p = 0.0343), and total rASRM score (p = 0.0223). Moreover, CD44 expression was negatively correlated with the presence of peritoneal endometriotic lesions (p = 0.0304) while E-cadherin expression was negatively correlated with the presence of deep infiltrating endometriosis (p = 0.0445).

CONCLUSIONS

Increased expression of Oct-4 and decreased expression of adhesion molecules in endometriotic tissues may contribute to the development and progression of endometriosis.

The impact of hyaluronan-enriched culture medium and intrauterine infusion of human chorionic gonadotropin on clinical outcomes in blastocyst transfer cycles

Over the last few decades, advances in ovarian hormonal stimulation, embryology laboratory technologies and embryo genetic testing, have significantly enhanced clinical outcomes in human assisted reproduction technologies (ART). However, embryo implantation remains a major bottleneck in achieving better pregnancy and live birth rates. Thus, there is growing interest in establishing new approaches to enhance implantation efficiency after embryo transfer. With advanced molecular techniques, many promising biomarkers associated with embryonic and endometrial changes occurring prior to and during embryo implantation have been identified. However, despite the progress in applying novel procedures into IVF practice, clinical evaluation of those biomarkers has so far reached modest predictive value for enhancing blastocyst developmental potential and endometrial receptivity. Therefore, other simpler strategies have also been introduced to increase the rates of successful clinical pregnancies and live births. One of these approaches is to investigate the impact of using embryo transfer medium containing high concentrations of an adherence compound, such as hyaluronic acid (HA), on IVF outcomes. Additionally, intrauterine infusion of a small volume of human chorionic gonadotropin (hCG) at the time of embryo transfer (ET) has also been proposed as a technique that might be advantageous for increasing the clinical outcomes, considering the fact that hCG plays a critical role in synchronizing endometrial and fetal development. However, the current findings from both interventions remain controversial, demonstrating a mixture of positive and indifferent results of these treatments in ART cycles. Further research will be crucial for a better understanding of the molecular mechanism of cross-talk between the blastocyst and the maternal endometrium during the optimal implantation period when using either hyaluronan-enriched medium or hCG infusion before embryo transfers. Therefore, this review aims to present existing literature related to both treatments, emphasizing their effects on blastocyst implantation.Abbreviations: ART: assisted reproduction technologies; HA: hyaluronic acid; hCG: human chorionic gonadotrophin; IVF: in vitro Fertilization; ET: embryo transfer; pH: hydrogen ions; CO2: Carbone dioxide; O2: Oxygen; PGT: pre-implantation genetic testing; FET: frozen embryo transfer; PCOS: Polycystic ovarian syndrome; DNA: deoxyribonucleic acid; miRNA: micro-ribonucleic acid; EVs: extracellular vesicles; ERA: endometrial receptivity array; CD44 and RHAMM: primary hyaluronan surface receptors; RCT: randomized clinical trials; LBR: life birth rate; CPR: clinical pregnancy rate; IR: implantation rate.

MicroRNA-200c impairs uterine receptivity formation by targeting FUT4 and α1,3-fucosylation

Successful embryo implantation requires the establishment of a receptive endometrium. Poor endometrial receptivity has generally been considered as a major cause of infertility. Protein glycosylation is associated with many physiological and pathological processes. The fucosylation is catalyzed by the specific fucosyltransferases. Fucosyltransferase IV (FUT4) is the key enzyme for the biosynthesis of α1,3-fucosylated glycans carried by glycoproteins, and the previous studies showed FUT4 expression changed dynamically during perimplantation. MicroRNAs (miRNAs) are known to regulate specific gene expression. However, the relationship between specific miRNA and FUT4, as well as the role of miRNA/FUT4 in the establishment of uterine receptivity remains elusive. In the current study, we reported that the levels of miR-200 family members were significantly increased in serum from infertility and abortion patients relative to healthy non-pregnancy and early-pregnancy women. Among these, miR-200c was the most sensitive diagnostic criterion for infertility by receiver operating characteristic curve analysis. FUT4 was lower in the serum from infertility and abortion patients compared with the healthy non-pregnancy and early-pregnancy women. Using endometrial cell lines and a mouse model, we demonstrated that miR-200c targeted and inhibited FUT4 expression, leading to the dysfunction of uterine receptivity. Our results also revealed that miR-200c decreased α1.3-fucosylation on glycoprotein CD44, which further inactivated Wnt/β-catenin signaling pathway. Taken together, miR-200c hampers uterine receptivity formation by targeting FUT4 and α1.3-fucosylation on CD44. miR-200c and FUT4 may be applied together as the potential markers for endometrial receptivity, and useful diagnostic and therapeutic targets for infertility.

Evaluation of transfer media containing different concentrations of hyaluronan for human in vitro fertilization

Purpose

The aim of the present prospective study was to investigate the efficacy of hyaluronan (HA) using two different concentrations as embryo transfer media for in vitro fertilization embryo transfer cycles.

Methods

A total of 169 cycles undergoing fresh embryo transfer on day 2 or 3, 561 cycles undergoing frozen‐thawed embryo transfer on day 2 or 3, and 484 cycles of frozen‐thawed blastocyst transfer were included in this study. Patients were randomly divided into two groups: transferred with low (l‐HA) or high (h‐HA) concentrations of HA in transfer media.

Results

In the case of fresh embryo transfer cycles, no significant differences were observed in the pregnancy (l‐HA 27.2%, h‐HA 31.2%), implantation (l‐HA 22.1%, h‐HA 24.2%), or abortion (l‐HA 24.0%, h‐HA 20.8%) rates between the two groups. In the case of frozen‐thawed embryo transfer cycles, no significant differences were noted in the pregnancy (l‐HA 20.9%, h‐HA 22.9%), implantation (l‐HA 13.4%, h‐HA 15.8%), or abortion (l‐HA 17.2%, h‐HA 21.5%) rates. In the case of frozen‐thawed blastocyst transfer cycles, no significant differences were observed in the pregnancy (l‐HA 46.0%, h‐HA 41.8%), implantation (l‐HA 45.8%, h‐HA 41.3%), or abortion (l‐HA 17.6%, h‐HA 26.9%) rates.

Conclusion

The present results showed that pregnancy, implantation, and abortion rates with transfer media containing different HA concentrations were similar.

Local and systemic factors and implantation: what is the evidence?

Significant progress has been made in the understanding of embryonic competence and endometrial receptivity since the inception of assisted reproductive technology. The endometrium is a highly dynamic tissue that plays a crucial role in the establishment and maintenance of normal pregnancy. In response to steroid sex hormones, the endometrium undergoes marked changes during the menstrual cycle that are critical for acceptance of the nascent embryo. There is also a wide body of literature on systemic factors that impact assisted reproductive technology outcomes. Patient prognosis is impacted by an array of factors that tip the scales in her favor or against success. Recognizing the local and systemic factors will allow clinicians to better understand and optimize the maternal environment at the time of implantation. This review will address the current literature on endometrial and systemic factors related to impaired implantation and highlight recent advances in this area of reproductive medicine.

CD44 expression in curettage and postoperative specimens of endometrial cancer

BACKGROUND

Adhesive molecules like CD44 are well defined key players in the metastatic cascade in many cancers, including endometrial cancer. They could play a role of markers of invasion, metastasis and prognostic factors.

AIM OF THE STUDY

The aim of the study is to assess a possible role of the CD44 as a marker of invasion in endometrial cancer, both at the moment of preoperative workup and final staging.

MATERIALS AND METHODS

Available for analysis were archival specimens of 51 patients who had underwent curettage and surgery between 2002 and 2007. An immunohistochemical study for CD44 expression was performed in curettage and postoperative specimens. Normal endometrium of 20 randomly chosen patients was used as a control group.

RESULTS

In endometrial cancer the expression of CD44 was significantly more intensive than in normal endometrium. In postoperative specimens, the CD44 expression was weaker in serous than in endometrioid cancer. There was no significant correlation between the adhesion molecule expression and clinicopathological features: grade,depth of invasion, cervical involvement, serosal and adnexal involvement, lymph-vascular space involvement, lymph node and distant metastases nor FIGO stage.

CONCLUSIONS

An increased expression of CD44 in endometrial cancer suggests its possible role in pathogenesis of this disease, however, it doesn't seem to be crucial. Different expression of the CD44 in endometrioid and papillary-serous type may reflect different pathogenesis of these types of cancer. No statistically proved relation between the investigated molecule expression and clinicopathological parameters suggests scepticism about its use in diagnostic process of endometrial cancer.

Expression of CD44 in endometrial stromal cells from women with and without endometriosis and its effect on the adherence to peritoneal mesothelial cells

OBJECTIVE

This study was performed to compare the expression of CD44 in endometrial stromal cells (ESCs) of women with and without endometriosis and to evaluate the role of CD44 in the adherence of ESCs to peritoneal mesothelial cells (PMCs).

METHODS

A PMC adherence assay was performed to evaluate the adherence of ESCs to PMCs in women with and without endometriosis. The expression of CD44 mRNA was measured by reverse transcription-polymerase chain reaction. CD44 protein was evaluated by Western blot analysis.

RESULTS

There were no significant differences in the expression of CD44 mRNA and protein in ESCs or in the binding of ESCs to PMCs between patients with endometriosis and controls. Although the expression of CD44 protein was decreased in both women with endometriosis and controls after anti-CD44 antibody treatment, there was no effect on binding of ESCs to PMCs. Treatment of ESCs with peritoneal fluid from endometriosis patients resulted in a significant increase in binding of ESCs to PMCs compared to untreated ESCs in the endometriosis group.

CONCLUSION

This study demonstrates that the expression of CD44 protein in ESCs from women with endometriosis might not be directly associated with adherence to PMCs.

Progesterone induction of chondroitin sulfate proteoglycan aggrecan expression in human endometrial epithelial cells

Chondroitin sulfate (CS) is the most abundant glycosaminoglycan species in the human endometrium, but the expression profile of CS proteoglycans (PGs) in this mucosal tissue remains fully undetermined. In this study, we aimed to clarify the expression of CSPGs including aggrecan, neurocan, melanoma-associated CSPG, neuroglycan C, and brevican in the human cycling endometrium. By reverse transcription-polymerase chain reaction, the gene transcripts for aggrecan core protein were detected in all samples examined, while other CSPGs were not. Western blotting showed the immunoreactivity for aggrecan core protein at approximately 370 kDa size after enzymatic digestion of CS-A and CS-C side chains. The expression level of aggrecan core protein was significantly higher in the secretory phase than in the proliferative phase. The immunostaining for aggrecan was detected in the endometrial microvascular endothelium throughout the menstrual cycle. The immunostaining in the glandular epithelium was faint during the proliferative and early secretory phase, but distinct during the mid-to-late-secretory phase. Progesterone, but not 17β-estradiol, induced aggrecan core protein expression in cultured endometrial epithelial cells. The endometrial expression pattern of aggrecan was distinct from that of other known CSPGs, suggesting the unique role of this proteoglycan at the implantation site.

Expression of E- and N-cadherin and CD44 in endometrium and hydrosalpinges from infertile women

In this prospective comparative study, compared with fertile control subjects (n = 12), infertile patients with hydrosalpinx (n = 18) had lower E-cadherin and a trend toward decreased N-cadherin H-scores in the endometrium (3.6 ± 0.6 vs. 2.4 ± 0.8 and 0.57 ± 1.0 vs. 0.52 ± 0.5, respectively). In hydrosalpinx, epithelial N-cadherin expression was discontinuous and disappeared in atrophic patches.

Menstrual endometrial cells from women with endometriosis demonstrate increased adherence to peritoneal cells and increased expression of CD44 splice variants

OBJECTIVE

We previously demonstrated that adherence of endometrial epithelial (EECs) and stromal cells (ESCs) to peritoneal mesothelial cells (PMCs) is partly regulated by ESC/EEC CD44 interactions with PMC associated hyaluronan. CD44, a transmembrane glycoprotein and major ligand for hyaluronan, has numerous splice variants which may impact hyaluronan binding. Here, we assessed whether ESCs and EECs from women with endometriosis demonstrate increased adherence to PMCs and examined CD44 splice variants' potential role in this process.

DESIGN

In vitro study.

SETTING

Academic medical center.

PATIENT(S)

Fertility patients with and without endometriosis.

INTERVENTION(S)

Menstrual endometrium was collected from women with and without endometriosis confirmed surgically. The adherence of ESC/EECs to PMCs was measured. The ESC/EEC CD44 splice variants were assessed using dot-blot analysis.

RESULT(S)

The ESCs and EECs from women with endometriosis demonstrated increased adherence to PMCs. The predominant CD44 splice variants expressed by ESCs and EECs from women with and without endometriosis were v3, v6, v7, v8, v9, and v10. The ESCs and EECs from women with endometriosis were more likely to express v6, v7, v8, and v9.

CONCLUSION(S)

Increased eutopic endometrial-PMC adherence and CD44 splice variant expression may contribute to the histogenesis of endometriotic lesions. Elucidation of factors controlling this expression may lead to novel endometriosis therapies.

Interleukin-11 and leukemia inhibitory factor regulate the adhesion of endometrial epithelial cells: implications in fertility regulation

Embryo implantation requires the closely harmonized processes of apposition, attachment, and adhesion of the conceptus to the maternal endometrial epithelium. IL-11 and leukemia inhibitory factor (LIF), two IL-6 family cytokines, are produced by the endometrium and are absolutely required for implantation in mice. We examined the effect of IL-11 and LIF on human endometrial epithelial cell adhesion. Both cytokines increased adhesion of primary human endometrial epithelial cells to fibronectin and collagen IV. IL-11 stimulated, whereas LIF had no effect on the adhesion of trophoblast to endometrial epithelial cells. Focused oligogene arrays were used to identify extracellular matrix and adhesion molecules mRNAs regulated by endometrial epithelial cells. We demonstrated by real-time RT-PCR and antibody arrays that both cytokines increased integrin-alpha2 mRNA and protein by endometrial epithelial cells. Signal transducers and activators of transcription (STAT)-3 inhibition reduced IL-11- and LIF-mediated epithelial cell adhesion to fibronectin, suggesting both cytokines regulated adhesion via phosphorylation of STAT3. Addition of either IL-11 neutralizing antibody and IL-11 or LIF and LIF antagonist to endometrial epithelial cells abolished cytokine induced phosphorylated STAT3. LIF but not IL-11 induced adhesion to collagen IV was reduced by an integrin-alpha2beta1 neutralizing antibody. This study demonstrated that IL-11 and LIF regulated endometrial epithelial cell adhesion, suggesting that targeting IL-11 and LIF may be useful in regulating fertility by either enhancing or blocking implantation.

Effect of low-dose mifepristone administration on day 2 after ovulation on transcript profiles in implantation-stage endometrium of rhesus monkeys

Progesterone is essential for endometrial receptivity in primates. In studies previously performed using global gene profiling based on microarray technology, attempts have been made to identify changes in gene expression between early luteal-phase and mid-luteal-phase endometria. However, the issue of the putative impact of preimplantation embryo-derived signal in the process of endometrial receptivity was missing in the previous studies. In the present study, an attempt has been made to delineate the transcripts profile in implantation-stage endometrium under combinatorial regulation of progesterone and embryo-derived signal in the rhesus monkey. To this effect, we have compared transcript profiles for 409 known genes between control receptive stage (n=13), and mifepristone-induced desynchronized and non-receptive stage (n=12) monkey endometrial samples collected on days 4 (n=12) and 6 (n=13) after ovulation from mated, potential conception cycles, using cDNA arrays containing sequence-verified clones. Statistical analysis of correlation of estimated transcript abundance between arrays and qRT-PCR for nine selected gene products yielded significant (P<0.05) concordance. Of 409 genes, a total of 40 gene transcripts were seen to be affected, nine gene transcripts in endometrial samples were found to progressively increase between days 4 and 6 following mifepristone treatment, while an additional five genes showed differential expression profile depending on the day after treatment. Additionally, different sets of 12 and 14 gene products showed changes in days 4 and 6 post-ovulation samples respectively. A new cohort of 28 gene products in implantation-stage endometrium was seen to be affected by luteal-phase mifepristone.

Hyaluronan in follicular fluid and embryo implantation following in vitro fertilization and embryo transfer

PURPOSE

To determine whether the concentration of hyaluronan (HA) in follicular fluid predicts implantation success following embryo transfer.

METHODS

Follicular fluids from 170 IVF patients were tested by ELISA for HA concentration.

RESULTS

The mean (standard error) HA concentration in follicular fluids was 158.0 (21.9) ng/ml from women whose embryos did not implant, 220.0 (21.3) ng/ml from women in which one embryo implanted and 239.3 (40.1) ng/ml from women with 2-3 implantations (implantation vs. no implantation p = .019). The HA level was unrelated to maternal age, number of oocytes harvested or fertilized or number of embryos transferred. Follicular fluids from women with an endocrine problem had a lower mean HA level (142.0 ng/ml) as compared to women undergoing IVF due to male factor infertility (257.3 ng/ml) (P = .05).

CONCLUSIONS

HA in follicular fluid is decreased in women with unsuccessful implantation or with an endocrine disorder. A woman's level of HA production may influence the potential for implantation of her embryos.

The Krüppel-like factor 9 (KLF9) network in HEC-1-A endometrial carcinoma cells suggests the carcinogenic potential of dys-regulated KLF9 expression

BACKGROUND

Krüppel-like factor 9 (KLF9) is a transcriptional regulator of uterine endometrial cell proliferation, adhesion and differentiation; processes essential for pregnancy success and which are subverted during tumorigenesis. The network of endometrial genes controlled by KLF9 is largely unknown. Over-expression of KLF9 in the human endometrial cancer cell line HEC-1-A alters cell morphology, proliferative indices, and differentiation, when compared to KLF9 under-expressing HEC-1-A cells. This cell line provides a unique model for identifying KLF9 downstream gene targets and signaling pathways.

METHODS

HEC-1-A sub-lines differing in relative levels of KLF9 were subjected to microarray analysis to identify differentially-regulated RNAs.

RESULTS

KLF9 under-expression induced twenty four genes. The KLF9-suppressed mRNAs encode protein participants in: aldehyde metabolism (AKR7A2, ALDH1A1); regulation of the actin cytoskeleton and cell motility (e.g., ANK3, ITGB8); cellular detoxification (SULT1A1, ABCC4); cellular signaling (e.g., ACBD3, FZD5, RAB25, CALB1); and transcriptional regulation (PAX2, STAT1). Sixty mRNAs were more abundant in KLF9 over-expressing sub-lines. The KLF9-induced mRNAs encode proteins which participate in: regulation and function of the actin cytoskeleton (COTL1, FSCN1, FXYD5, MYO10); cell adhesion, extracellular matrix and basement membrane formation (e.g., AMIGO2, COL4A1, COL4A2, LAMC2, NID2); transport (CLIC4); cellular signaling (e.g., BCAR3, MAPKAPK3); transcriptional regulation [e.g., KLF4, NR3C1 (glucocorticoid receptor), RXRalpha], growth factor/cytokine actions (SLPI, BDNF); and membrane-associated proteins and receptors (e.g., CXCR4, PTCH1). In addition, the abundance of mRNAs that encode hypothetical proteins (KLF9-inhibited: C12orf29 and C1orf186; KLF9-induced: C10orf38 and C9orf167) were altered by KLF9 expression. Human endometrial tumors of high tumor grade had decreased KLF9 mRNA abundance.

CONCLUSION

KLF9 influences the expression of uterine epithelial genes through mechanisms likely involving its transcriptional activator and repressor functions and which may underlie altered tumor biology with aberrant KLF9 expression.

Prokineticin 1 signaling and gene regulation in early human pregnancy

Prokineticin 1 (PROK1) is a recently described protein with a wide range of functions including tissue-specific angiogenesis, modulation of inflammatory responses, and regulation of hematopoiesis. The objective of this study was to investigate the role of PROK1 and prokineticin receptor 1 (PROKR1) in human endometrium during early pregnancy. PROK1 and PROKR1 expression is significantly elevated in first-trimester decidua, compared with nonpregnant endometrium. Expression of PROK1 and PROKR1 was localized in glandular epithelial and various cellular compartments within the stroma. To investigate the signaling pathways and target genes activated by PROK1, we generated an endometrial epithelial cell line stably expressing PROKR1 (Ishikawa PROKR1 cells). PROK1-PROKR1 interaction induced inositol phosphate mobilization and sequential phosphorylation of c-Src, epidermal growth factor receptor, and ERK 1/2. Gene microarray analysis on RNA extracted from Ishikawa PROKR1 cells treated with 40 nm PROK1 for 8 h revealed 49 genes to be differentially regulated. A number of these genes, including cyclooxygenase (COX)-2, leukemia inhibitory factor, IL-6, IL-8, and IL-11 are regulated in the endometrium during implantation and early pregnancy. We subsequently investigated the effect of PROK1 on expression of COX-2 in Ishikawa PROKR1 cells and first-trimester decidua. COX-2 mRNA and protein expression, and prostaglandin synthesis, were elevated in response to treatment with PROK1. Moreover, expression of COX-2 by PROK1 was dependent on activation of the Gq-phospholipase C-beta-cSrc-epidermal growth factor receptor-MAPK/ERK kinase pathway. These data demonstrate that PROK1 and PROKR1 expression is elevated in human decidua during early pregnancy and that PROK1-PROKR1 interaction regulates expression of a host of implantation-related genes.

Evaluation of a transfer medium containing high concentration of hyaluronan in human in vitro fertilization

OBJECTIVE

To examine whether a high concentration of recombinant hyaluronan in the embryo transfer (ET) medium can influence pregnancy rates in humans.

DESIGN

Retrospective, matched group study.

SETTING

Private and university hospital in vitro fertilization (IVF) units.

PATIENT(S)

Couples undergoing IVF or intracytoplasmic sperm injection (ICSI) were divided in two groups. In group 1 (402 patients), ET was performed with an ET medium containing a high concentration of recombinant hyaluronan in the presence of recombinant human serum albumin (HSA). In group 2 (425 couples), ET was performed with a medium containing a lower concentration of hyaluronan and HSA.

INTERVENTION(S)

IVF and ICSI.

MAIN OUTCOME MEASURE(S)

The two groups were compared for pregnancy rates according to the woman's age, the technique used (IVF or ICSI), the number of embryos transferred, and the day of ET.

RESULT(S)

Between the two groups, no statistically significant differences were observed in the total pregnancy rates after IVF or ICSI. Similarly, the pregnancy rates did not differ between the two groups when subdivided according to the woman's age, the number of embryos transferred (one to four), or the day of ET (2, 3, or 5 after oocyte pick up).

CONCLUSION(S)

The use of an ET medium with a high concentration of hyaluronan does not appear to have any statistically significant effect on pregnancy rates.

Temporal variation in the distribution of hyaluronic acid, CD44s, and CD44v6 in the human endometrium across the menstrual cycle

Tissues undergoing rapid growth and regeneration contain hyaluronic acid (HA) as a prominent component of the extracellular matrix. The physiologic role of HA is partly mediated by its relationship with CD44, its major cell surface receptor. Given the extensive remodeling of the endometrium during the menstrual cycle, the authors sought to determine whether these changes are related to the levels of HA, CD44s, and CD44v6 in the endometrium. Archival paraffin embedded cell blocks from 10 cases of proliferative endometrium and 20 cases of secretory endometrium were retrieved from the surgical pathology files. Specimens from the secretory phase were subdivided into three categories: early secretory (day 15-18), mid-secretory (day 19-23), and late secretory (day 24-28). All cases were stained for hyaluronic acid, CD44s, and CD44v6. Sections from umbilical cord, tonsil, and squamous cell carcinoma served as positive controls for HA, CD44s, and CD44v6, respectively. Positive staining was defined as droplet to diffuse intracytoplasmic or extracellular staining for HA and uniform membranous staining for CD44. During the proliferative phase, the endometrial glands and the stroma were both negative for CD44s and CD44v6 in all cases. In the secretory phase, the endometrial glands were negative for CD44s in all cases, but CD44v6 was expressed in 12 (60%) of cases. In contrast, the stromal cells expressed CD44s in 18 (90%) cases and were negative for CD44v6 in all cases. HA staining was present in the endometrial stroma throughout the menstrual cycle but was most intense (3+) and diffuse during the midsecretory phase. There was perivascular staining for HA throughout the cycle; it was most intense adjacent to the spiral arterioles in the secretory phase. These data indicate temporal and geographic differences in HA and CD44 staining in the endometrium in concert with the menstrual cycle. The timing of peak staining of HA and CD44s in the stroma and the upregulation of CD44v6 in secretory glands are coincident with the period in which the endometrium is most receptive to embryo implantation. Whether these changes are mere hormonal consequences or actually help modulate the cyclical changes in the endometrium warrants further study.

Histochemical evaluation of angiogenesis in endometrial adenocarcinoma

The formation of new vessels from endothelial cells, termed angiogenesis, is a complex process that is controlled by numerous paracrine factors. Vacularization of tumor tissue is a prerequsite for tumor growth and enables the dissemination of tumor cells throughout the body. Angiogenesis is classically assessed by counting the vessels or clusters of endothelial cells after selective immunohistochemical staining. In this study, vascularization of tumor tissue was evaluated quantitatively in 36 cases of stage I endometrial adenocarcinoma. The goal of this study was to evaluate whether the microvessel density correlates with the invasion potential of endometrial adenocarcinoma. The results show an increase in the number of endothelial cells at different stages in endometrial adenocarcinoma stage I and a strong positive correlation between the endothelial-to-stromal ratio and tumor grading.

Implantation markers and endometriosis

The receptive phase of the endometrium seems to occur in close association with the appearance of pinopodes and endometrial integrins that may be activated by the interleukin-1 system (IL-1). Embryo attachment is the result of adhesion protein expression, and the invasion of the embryo is governed by proteolytic enzymes. Leukaemia inhibitory factor (LIF) is produced by natural killer lymphocytes that interact with the invading trophoblast. This may activate urokinase plasminogen activator (uPA) and gelatinase enzymes, which play a crucial role in trophoblast invasion. Oestrogen stimulates, while progesterone inhibits, LIF. The role of endometrial contractility in displacing human embryos from the Fallopian tube to the lumen cavity of the uterus or vagina in terms of pregnancy or wastage is still a matter of discussion. Endometriosis and its associated abnormal uterine contractions may be also linked to implantation failure. Unless new evidence emerges to indicate otherwise, it can be assumed that progesterone is, either in a direct (non-genomic: contractility) or indirect (genomic: decidualization) manner, the only determinant of endometrial priming necessary for embryo nidation.

Mesothelial cell-associated hyaluronic acid promotes adhesion of endometrial cells to mesothelium

OBJECTIVE

To evaluate the role of hyaluronic acid in the attachment of endometrial cells to mesothelium.

DESIGN

In vitro study of adhesion of endometrial stromal and epithelial cells to mesothelial cells.

SETTING

University medical center.

PATIENT(S)

Reproductive-age women without endometriosis undergoing surgery for benign conditions.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The effect of hyaluronidase treatment of mesothelial cells or endometrial cells on adhesion of (51)Cr labeled endometrial stromal and epithelial cells to monolayers of mesothelium was evaluated. The expression of CD44, the hyaluronate receptor, was evaluated by western blot.

RESULT(S)

Hyaluronidase pretreatment of mesothelial cells decreased the binding of endometrial stromal and epithelial cells to mesothelium by 39% (P< .02) and 31% (P< .03), respectively. There was no effect on endometrial cell binding to mesothelial cells or to collagen IV when the endometrial cells were pretreated with hyaluronidase. CD44 expression by endometrial stromal and epithelial cells was demonstrated by western blot.

CONCLUSIONS

This study demonstrates that mesothelial cell-associated hyaluronic acid is involved in attachment of endometrial stromal and endometrial epithelial cells to the mesothelium. We hypothesize that binding of hyaluronic acid by endometrial cells is involved in the pathogenesis of the early endometriotic lesion.

Endometrial quality in infertile women with endometriosis

Several analyses in our infertility (IVF) and oocyte donation programs were carried out to gain clinical knowledge of the factors involved in the etiology of endometriosis-associated infertility. We first compared the IVF outcomes in women with tubal infertility and endometriosis. The results indicated that patients with endometriosis had a poorer IVF outcome in terms of reduced pregnancy rate per cycle, per transfer, and reduced implantation rate per embryo replaced. We then evaluated embryo development in vitro in women with and without endometriosis who underwent IVF and embryo replacement 72 hours after oocyte retrieval. We observed that compared to controls, patients with endometriosis had a significantly reduced number of blastomeres per embryo as well as an increased incidence of arrested embryos in vitro. In subsequent studies we compared fertility parameters in patients receiving donor oocytes. We noted that when donor oocytes came from patients without known endometriosis, embryo development and implantation rates were similar in patients with and without endometriosis. However, when the results of oocyte donation were classified according to the nature of the oocytes donated, patients who received embryos derived from oocytes from women with endometriotic ovaries showed a significantly reduced implantation rate compared to the controls. Taken together, these observations suggest that IVF in patients with endometriosis may be related to alterations within the oocyte, which, in turn, result in embryos of lower quality with a reduced ability to implant.

CD44s expression is reduced in endometriotic lesions compared to eutopic endometrium in women with endometriosis

Immunohistochemical expression of the standard form of CD44 (CD44s) was examined in archival formalin-fixed endometriotic and matching eutopic endometrial tissue obtained from 25 patients in proliferative (N = 16) and secretory (N = 9) stages of the cycle. CD44s was expressed in most eutopic endometria and endometriotic tissue. Its expression was significantly higher in secretory than in proliferative phase endometrium. It was low but detectable in 13 of 16 proliferative phase biopsies. The majority of these endometria exhibited both glandular and stromal staining (63%). In the secretory phase, glandular cells exhibited a significantly greater intensity of staining compared to stromal cells. In endometriotic tissue, stromal cell CD44s expression did not differ between tissue types in either stage of the cycle. In contrast, glandular expression in endometriotic tissue during the secretory phase was reduced (p < 0.05) compared to eutopic endometrium. It was absent in 66% of cases and reduced in the remaining cases. Our results indicate a correlation between CD44s expression and secretory differentiation of endometrial glands in the cycle, suggesting hormonal regulation of its expression. This cyclic pattern of CD44s expression was lost in corresponding endometriotic tissue. Reduced expression of CD44s in endometriotic tissue may provide insight into the pathophysiology of endometriosis.

Overexpression of CD44 variant 6 in human endometrial cancer and its prognostic significance

OBJECTIVE

We evaluated the prognostic significance of CD44 isoform CD44 V6 in endometrial cancer.

METHOD

Immunohistochemistry was used to determine the expression of CD44 V6 in 78 randomly selected endometrial cancer specimens.

RESULTS

CD44 V6 was detected in 53% (41/78) of the tumor samples. Clinicopathological evaluation revealed an inverse correlation with CD44 V6 expression and conventional poor prognosticators such as lower segment involvement, nuclear and structural grade, myometrial invasion, serosal involvement, lymph-vascular space invasion, and adnexal metastasis. Furthermore, the CD44 V6-negative group was found to be associated have a higher recurrence rate and a shorter disease-free survival.

CONCLUSION

These findings indicate that absence of CD44 V6 expression in cases of endometrial cancer might be coupled with a more aggressive course.

In vitro expression of soluble and cell surface-associated CD44 on endometrial cells from women with and without endometriosis

BACKGROUND

Endometriosis is one of the most common benign gynaecological diseases, and attachment of retrogradely shed viable endometrial cells is considered to be important in its development. CD44 is a multifunctional adhesion molecule that undergoes alternative splicing, giving rise to different isoforms.

METHODS

The expression of cell surface-associated CD44 std, v4, v5, v6 and v10 variants before and after cytokine treatment was investigated in endometrial cultures derived from 10 endometriosis patients and 22 women without the disease using immunocytochemistry. The immunoreactivity of soluble CD44 std, v5 and v6 variants was measured in culture medium using an enzyme immunoassay kit.

RESULTS

We report on the presence of soluble CD44 in endometrial culture supernatants. In particular, circulating CD44 standard form levels were significantly higher than levels of splice variants. We also found that both epithelial and stromal cells express surface-associated CD44 molecules in a distinct pattern and that this expression is not modulated by tumour necrosis factor (TNF)-alpha or/and interleukin 1 (IL-1) alpha/beta. Finally, cell surface-associated as well as soluble CD44 expression was similar in the two groups.

CONCLUSION

Our results indicate that endometrial cells can serve as a source of circulating CD44, but a direct role in the pathogenesis of endometriosis is rather improbable.

The prognostic value of CD44 isoform expression in endometrial cancer

Isoforms of the transmembrane glycoprotein CD44 have been implicated in tumour cell adhesion, tumour differentiation and metastatic spread in various human malignancies. We investigated the expression of CD44 isoforms containing variant exons v3, v5, v6 and v7-8 in 156 human endometrium cancer specimens by means of immunohistochemistry. CD44 isoforms CD44v3, CD44v5, CD44v6 and CD44v7-8 were detected in 26% (41 out of 156), 31% (48 out of 156), 22% (35 out of 156) and 15% (23 out of 156) of the tumour samples respectively. The expression of CD44 isoforms CD44v3, CD44v5 and CD44v7-8 showed no prognostic impact. In the univariate analysis, the expression of CD44v6 showed an association with shortened overall survival (log-rank test, P = 0.06). Multivariate analysis correcting for the confounding variable histological grading revealed CD44v6 not to be a prognostic factor in endometrial cancer (log-rank test, P = 0.06). Comparing the expression of CD44 isoforms CD44v3, CD44v5, CD44v6 and CD44v7-8 in 45 specimens of normal endometrial tissue, we found an up-regulation of all investigated CD44 isoforms in the secretory phase compared with the proliferative phase of the menstrual cycle. Our data indicate that the expression of CD44 isoforms, while obviously playing a role in the functional changes of normal endometrium, is not an adverse predictive factor in endometrial cancer.

CD44 exon v6 is not implicated in the progression and metastasis of endometrial cancer

We examined the presence of mRNA for CD44v6 and assessed the association with clinicopathological features in 42 patients with endometrial cancer by RT-PCR and subsequent Southern blot hybridization with oligonucleotide probe specific for v6. The standard form of CD44 was expressed in all specimens and 20 out of 42 endometrial cancers expressed an isoform containing exon v6 in combination with other variant exons. However, there was no correlation between the expression of CD44v6 and any clinicopathological factors. These findings suggested that the expression of CD44v6 is not implicated in the progression and metastasis of endometrial cancer.

CD44 and CD44v6 downregulation in clinical prostatic carcinoma: relation to Gleason grade and cytoarchitecture

BACKGROUND

Altered expression of CD44 has been implicated in tumor progression and metastasis in multiple neoplasms.

METHODS

CD44 expression in archival tissues of prostate carcinoma was examined by immunohistochemistry with monoclonal antibodies against core CD44 and the RNA splice variant CD44v6 (v6).

RESULTS

Core CD44 expression was reduced in the majority of primary neoplastic foci (n = 94) and loss of expression correlated with increasing Gleason grade. Staining for v6 was absent in most carcinomas and metastases. Expression of core CD44 in pelvic lymph node (n = 27) and bone metastases (n = 21) was significantly reduced. In addition, CD44 expression correlated with cytoarchitecture. Tall columnar tumor cells typically stained positively, yet more rounded cells forming cribiform structures or nests showed reduced expression. All cases of high-grade prostatic intraepithelial neoplasia were positive for core CD44 yet, there was decreased expression in cribiform and micropapillary variants.

CONCLUSIONS

The majority of clinically relevant human prostatic carcinomas and metastases downregulate expression of CD44. Additional studies to determine whether CD44 cell surface expression relates to clinical outcome independent of other established clinicopathologic risk factors are warranted.

CD44: structure, function, and association with the malignant process

CD44 is a ubiquitous multistructural and multifunctional cells surface adhesion molecule involved in cell-cell and cell-matrix interactions. Twenty exons are involved in the genomic organization of this molecule. The first five and the last 5 exons are constant, whereas the 10 exons located between these regions are subjected to alternative splicing, resulting in the generation of a variable region. Differential utilization of the 10 variable region exons, as well as variations in N-glycosylation, O-glycosylation, and glycosaminoglycanation (by heparan sulfate or chondroitin sulfate), generate multiple isoforms (at least 20 are known) of different molecular sizes (85-230 kDa). The smallest CD44 molecule (85-95 kDa), which lacks the entire variable region, is standard CD44 (CD44s). As it is expressed mainly on cells of lymphohematopoietic origin, CD44s is also known as hematopoietic CD44 (CD44H). CD44s is a single-chain molecule composed of a distal extracellular domain (containing, the ligand-binding sites), a membrane-proximal region, a transmembrane-spanning domain, and a cytoplasmic tail. The molecular sequence (with the exception of the membrane-proximal region) displays high interspecies homology. After immunological activation, T lymphocytes and other leukocytes transiently upregulate CD44 isoforms expressing variant exons (designated CD44v). A CD44 isform containing the last 3 exon products of the variable region (CD44V8-10, also known as epithelial CD44 or CD44E), is preferentially expressed on epithelial cells. The longest CD44 isoform expressing in tandem eight exons of the variable region (CD44V3-10) was detected in keratinocytes. Hyaluronic acid (HA), an important component of the extracellular matrix (ECM), is the principal, but by no means the only, ligand of CD44. Other CD44 ligands include the ECM components collagen, fibronectin, laminin, and chondroitin sulfate. Mucosal addressin, serglycin, osteopontin, and the class II invariant chain (Ii) are additional, ECM-unrelated, ligands of the molecule. In many, but not in all cases, CD44 does not bind HA unless it is stimulated by phorbol esters, activated by agonistic anti-CD44 antibody, or deglycosylated (e.g., by tunicamycin). CD44 is a multifunctional receptor involved in cell-cell and cell-ECM interactions, cell traffic, lymph node homing, presentation of chemokines and growth factors to traveling cells, and transmission of growth signals. CD44 also participates in the uptake and intracellular degradation of HA, as well as in transmission of signals mediating hematopoiesis and apoptosis. Many cancer cell types as well as their metastases express high levels of CD44. Whereas some tumors, such as gliomas, exclusively express standard CD44, other neoplasms, including gastrointestinal cancer, bladder cancer, uterine cervical cancer, breast cancer and non-Hodgkin's lymphomas, also express CD44 variants. Hence CD44, particularly its variants, may be used as diagnostic or prognostic markers of at least some human malignant diseases. Furthermore, it has been shown in animal models that injection of reagents interfering with CD44-ligand interaction (e.g., CD44s- or CD44v-specific antibodies) inhibit local tumor growth and metastatic spread. These findings suggest that CD44 may confer a growth advantage on some neoplastic cells and, therefore, could be used as a target for cancer therapy. It is hoped that identification of CD44 variants expressed on cancer but not on normal cells will lead to the development of anti-CD44 reagents restricted to the neoplastic growth.