Targeting leiomyomas with all-trans-retinoic acid at phosphoinositide 3-kinase pathway suppression: Effective roles of ß-catenin and of signaling interactions.

AIM: Leiomyomas, monoclonal tumors developed by the transformation of myometrium somatic stem cells, are a major health concern that can severely impair quality of life. Pathological alterations of signaling pathways have been recognized as a key feature in a variety of human diseases. Our objective was to analyze treatment with all-trans-retinoic acid (ATRA) by suppression of the phosphoinositide 3-kinase (PI3K) pathway on growth, signaling pattern and interactions among PI3K/B-cell lymphoma 2 (Bcl2)/retinol leiomyoma proteins. METHODS: Cultures of paired myometrium and leiomyoma cells from premenopausal women undergoing hysterectomy were collected. Western blot and analysis of variance were used for analysis. RESULTS: Significant differences were detected between treatment with ATRA alone or with LY294002 (a PI3K growth suppressor) in response to treatment and among cell samples and cell numbers. Leiomyoma cells were less affected. Immunochemical analysis of signaling patterns demonstrated that treatments affected most of the examined protein levels differently. Significant differences between the cell type responses to treatment in pyruvate phosphate dikinase 1 (pPDK1), Bad and pß-catenin levels were identified. The pß-catenin level showed highly significant interaction between response to treatment and cell type. CONCLUSIONS: ATRA treatment on PI3K pathway suppression significantly affected growth, signaling pattern and interactions among PI3K/Bcl2/retinol proteins involved in the growth, survival and apoptosis of leiomyomas. Interpretation of our results suggests that increasing knowledge of the role of signaling interplay in the pathogenesis of leiomyomas may present an opportunity to use specific signal transduction inhibitors for treating and preventing this disorder.

Surgical versus medical treatment for secondary post-partum hemorrhage.

BACKGROUND: Secondary post-partum hemorrhage (PPH) is defined as any abnormal bleeding from the birth canal occurring between 24 hours and 12 weeks postnatally. Treatment usually falls into one of the two categories: surgical evacuation of the uterus or medical treatment. OBJECTIVE: To compare the two different clinical approaches and the implications on future fertility. STUDY DESIGN: A retrospective study. SETTING: From 1990 to 2002, 168 women diagnosed with late PPH were admitted to the Hadassah Medical Centers in Jerusalem. The cases were divided into two groups according to the planned initial treatment: primary surgical treatment vs. primary medical treatment. RESULTS: Primary surgical treatment was associated with significantly more primary negative events (p=0.01). After the primary event, primary surgical treatment was associated with fewer future deliveries (p=0.04) and resulted in increased rate of secondary infertility of borderline significance (p=0.06). CONCLUSIONS: Our results show that secondary PPH is related to high rates of immediate and long-term complications. It is possible that a conservative medical approach for secondary PPH may be superior to surgical treatment.

Mifepristone followed by high-dose oxytocin drip for second-trimester abortion: a randomized, double-blind, placebo-controlled, pilot study.

OBJECTIVE: To study the effect of mifepristone for priming and induction of second-trimester abortion in conjunction with a high-concentration oxytocin drip. STUDY DESIGN: Prospective, randomized, placebo-controlled, pilot study. Thirty patients with 14-25 weeks' gestational age abortion received either 600 mg of mifepristone or placebo in 3 identical capsules followed, 48 hours later, by a high-concentration oxytocin drip (HCOD). RESULTS: The mifepristone group showed significantly higher success rates as compared to the placebo group (92.3% vs. 52.9%, p<0.05). The time interval to abortion (from beginning of HCOD) was also significantly shorter in the mifepristone group as compared to the placebo group (11.3 +/- 6.0 hours vs. 17.6 +/- 6.5 hours, p <0.05). Probability of success as calculated by the Kaplan-Meier method was found to be highly significant (log rank test p = 0.001). CONCLUSION: Our results suggest that mifepristone is very effective for priming and induction of second-trimester abortion and shortens significantly the time interval to evacuation following HCOD.

[Chronic pelvic pain and Allen-Masters syndrome].

Allen-Masters syndrome, first described at 1955, is considered an uncommon etiology for chronic pelvic pain. The syndrome associates traumatic delivery to lacerations found on the posterior leaf of the broad Ligament. The authors report the clinical and laparoscopic findings of a female patient who was admitted to their department for evaluation due to chronic pelvic pain. The patient had a history of normal delivery six months before her admission. In the laparoscopy the authors reported finding bilateral Lacerations in the posterior leaf of the broad Ligament. Coagulation of both lacerations was performed and the patient reported significant improvement in her complaints. The relevant literature was reviewed and the article discusses the process of diagnosis and treatment.

[Fallopian tube torsion--a rare complication in the reproductive age].

Isolated fallopian tube torsion (ITT) is a rare condition defined as a total or partial rotation of the fallopian tube around its vascular axis. The torsion initiaLLy interferes with the venous and lymphatic circulation. If unrelieved in time, rapid progression occurs, occluding the arterial circulation and Leading to gangrene and hemorrhagic necrosis. The cLinicaL appearance usually includes sharp lower abdominal pain, with or without peritoneal signs. Urinary and gastrointestinal signs might also occur. isolated fallopian tube is a rare condition; the incidence s estimated to be 1:500,000 mostly in reproductive age women. ITT is most common in the right side, although several reports claim that there is no difference between the sides. The etiology is not completely understood, but tubal anomalies (anatomic or physiologic) as well as trauma or pelvic inflammation are predisposing factors. The clinical appearance and the imaging in these cases are not pathognomonic, and many cases are delayed by means of diagnosis and treatment. The treatment is surgical. Detorsion or salpingectomy is usually performed by laparoscopy. Three cases that were treated lately at the Department of Obstetrics and Gynecology at the Hadassah Medical Center are presented together with a review of the literature.

Ultrasound-diagnosed puerperal osteopenia in young primiparas.

OBJECTIVE: To study whether osteopenia occurs following pregnancy and to evaluate its severity in young primiparas. STUDY DESIGN: A prospective case control study. Sixty-one young primigravidae early after birth and 59 nulligravidae matched for age and BMI participated in the study. Bone status was examined using ultrasonic bone transmission velocity over the tibia; Z-score and T-score for bone density were calculated. Serum bone alkaline phosphatase, osteocalcin and urinary N-telopeptide crosslinks were evaluated as bone remodeling biochemical markers. RESULTS: Ultrasonic parameters of bone status following delivery were significantly lower in the puerperal group as compared to the nulligravida group. Serum mean bone alkaline phosphatase levels and urinary N-telopeptide crosslinks secretion were higher by 50% in the puerperal group, while serum osteocalcin levels were significantly lower (by 25%) than in the nulligravida controls. A positive correlation between ultrasonic measurements and biochemical markers was demonstrated in the postpartum group, whereas the control group showed a negative correlation. CONCLUSION: Women at their early puerperium demonstrate a significant cortical bone mass reduction as measured by ultrasonograph and markers of bone turnover. It appears that pregnancy is a state of unbalanced accelerated bone turnover that may be associated with reduced osteoblastic activity.

Preparation of low density lipoprotein from large apheresis cartridges for induction of cell death in Saos2 osteoblasts.

Atherosclerosis is epidemiologically associated with postmenopausal osteoporosis presumably by common etiologic factors, reflecting a state of comorbidity in aging. Osteoblasts make a significant facet of this comorbidity state. The present study shows that LDL (native and oxidized) separated by conventional density ultracentrifugation induces osteoblast cell growth arrest in culture. Since the density unltracentrifugation is a tedious procedure we examined, in the present study, the option of LDL purification by ionic strength elution from LDL-apheresis cartridges. We tested the ability of LDL and oxidized LDL (oxLDL) from apheresis columns to induce apoptosis in human Saos2 osteoblasts. Isotonic NaCl effluent washed from LDL-apheresis columns (before starting elution of LDL) induced cell proliferation. In some of the effluent fractions that stimulated Saos2 osteoblasts, up to 15% of the stimulation levels could be significantly inhibited with antilipoprotein A antibodies. After the isotonic washing (150 mM NaCl), upon elution with high ionic strength, 0.2-0.3 M NaCl, some front-runner LDL eluate fractions also induced cell growth and others did not inhibit Saos2 cell growth. This indicates that these fractions might have been contaminated with apolipoprotein A or with other mitogenic compounds. In contrast, the late-to-elute (last 1/3) LDL portion, with a mean density of 1.042 g/mL, killed the cells as expected. This suggests that only the very last one third of LDL eluted by high ionic strength (0.3-0.5 M) is free of osteoblast-mitogenic compounds or lipoprotein-A containing particles. This approach to LDL purification might serve as a convenient and economic method for studying the composition of individual LDL particles and their interaction with cells in culture.

Physical symptoms and emotional responses among women undergoing induced abortion protocols during the second trimester.

OBJECTIVE: To compare the physical and emotional effects of two medical protocols for induced abortion during the second trimester. METHODS: The present study was part of a prospective randomized controlled trial comparing mifepristone followed by oxytocin or misoprostol that was conducted at the Hadassah Hebrew University Medical Center, Jerusalem, Israel, from January 10, 2009, to February 22, 2012. Inclusion criteria were pregnancy (14-24weeks), epidural analgesia, and medical induction of abortion (either elective or following missed abortion). A structured questionnaire was used to assess the participants' physical symptoms and emotional responses. The primary outcome for the present analysis was the degree of physical symptoms reported. RESULTS: Overall, 68 women in the oxytocin group and 67 in the misoprostol group received epidural analgesia and completed the questionnaire. As assessed using a five-point Likert scale, women in the misoprostol group were more likely than those in the oxytocin group to experience diarrhea (1.34±0.84 vs 1.10±0.55; P=0.05) and shivers (3.03±1.75 vs 1.75±1.21; P<0.001). No other between-group differences were detected for the physical or emotional variables evaluated. CONCLUSION: Differences in physical symptoms experienced by the two treatment groups did not influence the participants' subsequent emotional response. ClinicalTrials.gov: NCT00784797.

Reproduction and ulcerative colitis: a review.

Ulcerative colitis is a chronic inflammatory bowel disease. The onset peaks at age 15-30 years and coincides with the reproductive period. We screened and summarized the relevant English-language publications (Entrez-PubMed) on ulcerative colitis, fertility and pregnancy. The presence of ulcerative colitis per se does not seem to significantly alterfertility in young women. However, associated conditions, such as active disease, surgical interventions and medication, may interfere with reproduction. It is difficult to draw conclusions regarding the effect of ulcerative colitis on pregnancy outcome in terms of pregnancy loss, intrauterine growth restriction, low birth weight, preterm labor, stillbirth and perinatal mortality. Nevertheless, it appears that major complications do not occur in ulcerative colitis patients more frequently than in healthy women. The rate of exacerbation is probably the same for pregnant and nonpregnant women. Disease control during pregnancy is of the utmost importance. Fortunately, most drugs can by used safely during pregnancy.

[Prevention of venous thromboembolism in obstetric & gynecology--an update].

BACKGROUND: Thromboembolic events are quite common in obstetrics and gynecology and constitute a significant cause for morbidity and mortality. Recently, a decline in complication rates has been observed following the implementation of effective preventive measures. OBJECTIVE: This article aims to review the different prevention and treatment methods and to evaluate their efficiency. Furthermore, the article strives to forge a structured approach and form appropriate protocols for our population. RESULTS: Many studies have shown that the extensive use of preventive treatment is safe, clinically effective and valuable from the cost-benefit perspective. Nevertheless, most surveys performed around the world showed that the number of surgeons that use prophylactic treatment is lower than expected. In our department, we have engaged in a discussion with our hematologist and created protocols with simple and clear flow-charts for DVT and PE prevention, both in gynecological operations and in obstetrics. CONCLUSION: The implementation of a clear departmental policy will increase the awareness and the use of preventive treatment and will potentially decrease morbidity and mortality from thromboembolic events.

Perinatal outcome of pregnancies complicated by placenta accreta.

OBJECTIVE: The purpose of the study was to characterize the perinatal outcome of pregnancies complicated by placenta accreta. METHODS: We conducted a case-control analysis of all deliveries between the years 1990 and 2000 that were complicated by placenta accreta. Perinatal variables included in the analysis were gestational age at delivery, birth weight, Apgar scores, and perinatal mortality. Statistical analysis was performed using both the unpaired and paired approach. P <.05 was considered significant. RESULTS: The study encompassed 34,450 deliveries, from which 310 cases of placenta accreta were diagnosed (0.9%) and compared with 310 matched controls. In the pregnancies complicated by placenta accreta, we found a statistically significant increase in preterm deliveries (10.7% versus 1%, P <.001, odds ratio 12.1, 95% confidence interval 3.7-39.9) and small-for-gestational-age babies (27.3% versus 14%, P <.001, odds ratio 5.05, 95% confidence interval 1.46-3.28). CONCLUSION: Pregnancies complicated by placenta accreta are at increased risk for perinatal adverse outcome. We speculate that these findings may arise from pathological implantation of the placenta, resulting in interference with normal fetal growth.

Prelabor rupture of the membranes at term: when to induce labor?

OBJECTIVES: To determine the significant predictors of clinical chorioamionitis and neonatal infection in patients with prelabor rupture of the membranes at term, and to apply this information to determination of optimal timing of labor induction. STUDY DESIGN: A retrospective case control series of women at > or =37 weeks' with prelabor rupture of the membranes. The study group consisted of women with evidence of maternal or neonatal infection. Controls had no evidence of infection. Three types of management were compared. (1) Immediate induction of labor, (2) expectant management up to 24 h followed by induction of labor if still necessary, or (3) expectant management for over 24 h. Univariate and multivariate analyses were performed by stepwise logistic regression (SPSS software package). The size of the study and the control groups was calculated for a 90% power with two sided P value of 0.05 in order to demonstrate an odds ratio of 2 for expectant management (two groups: early and late) versus immediate induction of labor (132 and 279 women in the study and the control groups, respectively). RESULTS: The rate of expectant management for over 24 h versus expectant management until 24 h followed by induction of labor when still necessary, was higher among cases than among controls ( OR = 1.84; P < 0.017; 95% CI, 1.127-3.003). Conversely, the rate of immediate induction of labor versus expectant management until 24 h followed by induction of labor when still necessary, was also higher among cases ( OR = 2.66; P < 0.001; 95% CI, 0.222-0.644). CONCLUSION: In women with prelabor rupture of the membranes at term, the best approach is to induce labor if spontaneous labor has not begun after 24 h.

IUD use and the risk of endometrial cancer.

OBJECTIVE: Although the intrauterine device (IUD) is one of the most widely used forms of contraception throughout the world, its potential long-term effects on the uterus have not been thoroughly evaluated. This paper reports the long-term results of IUD use on the incidence of endometrial cancer. STUDY DESIGN: The data is part of a nationwide case-control, pilot study that was undertaken in order to evaluate the possible influence of ovulation induction drugs on the risk of endometrial cancer. The study included 128 living women 35-64 years old, with a histologically confirmed diagnosis of endometrial carcinoma. The controls were 255 women from the same dialing areas selected by random digit dialing. A multivariate logistic model, controlling for age, was used to assess the independent effects of factors found to be significantly associated with endometrial cancer on univariate analysis. RESULTS: The following parameters were found to be independently associated with endometrial cancer controlling for age: nulliparity OR=2.7 (95% CI 1.1-6.5, P=0.03); history of infertility OR=1.8 (95% CI 1.0-3.3, P=0.05); BMI>/=27 OR=2.3 (95% CI 1.4-3.8, P=0.001). The use of oral contraceptives and IUD were found to be protective; OR=0.29 and 0.37, respectively, (95% CI 0.14-0.61, P=0.001, 0.19-0.70, and 0.003, respectively). CONCLUSIONS: IUD use may have a protective effect on endometrial cancer risk. The protective effect of IUD may be either, through the intense inflammatory response that leads to other lisosomal and inflammatory actions, which may include cells responsible for early elimination of hyperplastic endometrial epithelial cells or, the more complete shedding of the endometrium associated with IUD use may decrease hyperplasia of the endometrium, a known risk factor for endometrial carcinoma.

Extreme caudal agenesis. Possible drug-related etiology?

BACKGROUND: Caudal regression syndrome (CRS) is a rare anomaly of the lower body pole that represents a continuum of congenital malformations ranging from isolated sacral agenesis to absence of the lumbosacral spine and major visceral anomalies. While the exact etiology of this syndrome is unclear, maternal diabetes, genetic factors, teratogens and vascular anomalies altering blood flow have been hypothesized to play a role in its pathogenesis. CASE: A fetus had extreme hypotrophy of the caudal body pole, aplasia of the lower spine and complete renal agenesis diagnosed in the second trimester by ultrasound. Maternal history revealed the use of minoxidil solution for preventing hair loss for four years prior to and during gestation. Also, the mother had taken trimethoprim-sulfamethoxazole during the first trimester for treatment of upper respiratory disease. No maternal diabetes or history of familial genetic diseases was evident. CONCLUSION: In an extreme form of CRS consisting of complete aplasia of the lower body pole and viscera and additional malformations, a possible drug-related etiology was suggested but should be confirmed by more studies.

Listeria infection during pregnancy: a 10 year experience.

BACKGROUND: Although Listeria monocytogenes is widely distributed in nature, it rarely causes clinical infection in previously healthy people. This microorganism, however, may cause severe invasive disease in pregnant women and newborns. OBJECTIVES: To investigate--in our pregnant population--the impact, severity and outcome of listeriosis on both mother and fetus. METHOD: The study was carried out at a level III, university two-hospital complex. In a retrospective chart review of 65,022 parturients during a 10 year period (1990-1999), we identified and evaluated 11 pregnant patients and their offspring with Listeria infection. RESULTS: Chorioamnionitis with multiple placental abscesses were observed in all five placentae examined. Clinically, 4 of 11 parturients had a cesarean section for fetal distress (36.3%), as compared to the 14% mean CS rate in our general population. Two of 11 had a late abortion (18.1%), as compared with the 4% rate in our hospital. Four of 11 had premature labor (36%), which was about four times the rate in our population. Finally, although no intrauterine fetal death was recorded in our series, there was one neonatal death of a term infant (1/11, 9%), which is about 10 times higher than our corrected perinatal mortality rate. CONCLUSIONS: If not promptly and adequately treated, listeriosis in pregnancy may present serious hazards to the fetus and newborn through direct infection of the placenta and chorioamnionitis.

Mifepristone followed by misoprostol or oxytocin for second-trimester abortion: a randomized controlled trial.

OBJECTIVE: To compare two methods for induction of second-trimester abortion after priming the cervix with mifepristone. METHODS: This was a randomized prospective trial carried out between January 2009 and February 2012. The participants were healthy women between 14 and 24 weeks of gestation with missed miscarriage or need for termination of pregnancy. All participants received oral 200 mg mifepristone and, after 36 hours, after randomization, were given either a high-concentration oxytocin drip (maximal dose of 150 milli-international units/min) for up to 36 hours or 800 micrograms misoprostol vaginally followed by 400 micrograms oral misoprostol every 3 hours with a maximum of four oral doses. If expulsion of the fetus was not achieved, another 200 mg mifepristone was administered and another course of misoprostol was delivered as described previously. The primary outcome measure was success expulsion of the fetus in 36 hours since starting on uterotonic agent. Secondary outcomes included time until expulsion of the fetus and rate of adverse outcomes. RESULTS: Success rates in the mifepristone-misoprostol and mifepristone-oxytocin arms were 100% (70/70 patients) and 95.8% (69/72), respectively (relative risk 1.043, 95% confidence interval 0.99-1.10, P=.13). Time until fetal expulsion was shorter in the mifepristone-misoprostol arm (7.0 ± 4.9 hours compared with 11.3 ± 7.4 hours, P<.001). However, the rate of adverse effects in the misoprostol group was higher than in the oxytocin group. Factors associated with a shorter time until expulsion were missed miscarriage compared with therapeutic abortion, increased ultrasonographic gestational age, and increased parity. CONCLUSION: The two regimens studied had comparable efficacy for induction of second-trimester abortion; however, the mifepristone-oxytocin regimen has a longer time until expulsion but with fewer side effects. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00784797. LEVEL OF EVIDENCE: : I.

All-trans-retinoic acid mediates changes in PI3K and retinoic acid signaling proteins of leiomyomas.

OBJECTIVE: To detect changes induced by all-trans-retinoic acid (ATRA) on the expression and activation of target proteins of the retinoic acid (RA) and PI3K/Akt pathways involved in leiomyoma growth. DESIGN: A study on human tissue cultures. SETTING: Hadassah University Hospital. PATIENT(S): Premenopausal women with uterine leiomyomas. INTERVENTION(S): Paired cultures of normal myometrium and leiomyomas, from women undergoing hysterectomy, were obtained. MAIN OUTCOME MEASURE(S): The effect of ATRA was examined on the expression and phosphorylation of relevant RA, PI3K/Akt, and Bcl2 proteins (immunochemical analysis), cell proliferation, cell cycle distribution, and apoptosis. RESULT(S): Applying our cell culture model, we demonstrated that ATRA induced changes in the expression and activation of the RA and PI3K/Akt pathway proteins in leiomyoma cells, with significant increases of alcohol dehydrogenase 1 and cyclin D2 protein levels. In part of the leiomyoma cells, ATRA induced a relative increase of Bax (proapoptotic) as well as a relative decrease of phosphorylated glycogen synthase kinase 3ß (proapoptotic). CONCLUSION(S): Our results highlight the involvement of ATRA in the RA and PI3K/Akt pathways, whose specific signaling products may influence the outcome of leiomyoma growth by regulating cell proliferation, apoptosis, and survival. These results might be useful for the on-going research into alternative methods for treating and preventing this disorder.

Changes related to phosphatidylinositol 3-kinase/Akt signaling in leiomyomas: possible involvement of glycogen synthase kinase 3alpha and cyclin D2 in the pathophysiology.

OBJECTIVE: To identify changes in the expression and phosphorylation of phosphatidylinositol 3-kinase (PI3K)/Akt protein kinases controlling survival and/or apoptosis of in vitro cell cultures of uterine leiomyomas. DESIGN: Establishment of paired cell cultures of leiomyoma and myometrial specimens. SETTING: Hadassah gynecology research laboratory. PATIENT(S): Eleven white premenopausal women, 35 to 50 years of age, undergoing hysterectomy because of symptomatic uterine leiomyomas. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Immunochemical analysis of expression and phosphorylation of relevant PI3K/Akt and BCL2 proteins. RESULT(S): Analysis of total phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and of nonphosphorylated and phosphorylated (p) PDK1, Akt, glycogen synthase kinase 3 (GSK3), FKHR, tuberin (TSC2) and hamartin (TSC1) complex, and cyclin D2 proteins indicated that [1] the level of pGSK3alpha and cyclin D2 proteins was elevated significantly in the leiomyoma compared with the normal myometrium, [2] there was a significant interaction between PTEN- PDK1 and between pAkt-pGSK3beta in the leiomyoma compared with the myometrial cells, and [3] there was a significant interaction between pAkt-pGSK3alpha in the paired leiomyoma and myometrial cultures. CONCLUSION(S): Our study suggests that the downstream signaling components of the PI3K/Akt pathway, GSK3 (a regulator of apoptosis), and cyclin D2 (a promoter of G1/S progression), as well as the significant interaction between PTEN-PDK and between pAkt-pGSK3beta, are involved in the survival and proliferation of leiomyomas.

Acetaldehyde differentially affects the growth of uterine leiomyomata and myometrial cells in tissue cultures.

OBJECTIVE: To examine the effect of alcohol and its derivatives on leiomyomata versus normal myometrium in cell culture. DESIGN: A study on human tissue cultures. SETTING: A tertiary-care university hospital. PATIENT(S): Premenopausal women with uterine myomas. INTERVENTION(S): Obtaining paired cultures of normal myometrium and myomas from women undergoing hysterectomy. MAIN OUTCOME MEASURE(S): Analysis of the effect of ethanol and acetaldehyde on cell growth and the expression of relevant proteins. RESULT(S): Acetaldehyde statistically significantly inhibited the growth of myoma cells compared with normal myometrium. The level of alcohol dehydrogenase 1 (ADH1) protein was lower in myoma than in myometrial cells. The acetaldehyde dehydrogenase 1 (ALDH1) protein level was higher in myoma cells. Treatment with acetaldehyde resulted in a relative reduction of ALDH1 level in the myoma cells. CONCLUSION(S): Acetaldehyde has an inhibitory effect on cell growth of myoma compared with normal myometrium. The reduced level of ADH1 and the increased level of ALDH1 proteins observed in myoma cell culture reduces the acetaldehyde level and thus may be involved in myoma cell growth.

Comprehensive gene and microRNA expression profiling reveals a role for microRNAs in human liver development.

BACKGROUND AND AIMS: microRNAs (miRNAs) are small noncoding RNAs that regulate cognate mRNAs post-transcriptionally. miRNAs have been implicated in regulating gene expression in embryonic developmental processes, including proliferation and differentiation. The liver is a multifunctional organ, which undergoes rapid changes during the developmental period and relies on tightly-regulated gene expression. Little is known regarding the complex expression patterns of both mRNAs and miRNAs during the early stages of human liver development, and the role of miRNAs in the regulation of this process has not been studied. The aim of this work was to study the impact of miRNAs on gene expression during early human liver development. METHODS: Global gene and miRNA expression were profiled in adult and in 9-12w human embryonic livers, using high-density microarrays and quantitative RT-PCR. RESULTS: Embryonic liver samples exhibited a gene expression profile that differentiated upon progression in the developmental process, and revealed multiple regulated genes. miRNA expression profiling revealed four major expression patterns that correlated with the known function of regulated miRNAs. Comparison of the expression of the most regulated miRNAs to that of their putative targets using a novel algorithm revealed a significant anti-correlation for several miRNAs, and identified the most active miRNAs in embryonic and in adult liver. Furthermore, our algorithm facilitated the identification of TGFbeta-R1 as a novel target gene of let-7. CONCLUSIONS: Our results uncover multiple regulated miRNAs and genes throughout human liver development, and our algorithm assists in identification of novel miRNA targets with potential roles in liver development.