Comparison of telomerase activity in normal chorionic villi to trophoblastic diseases

LPCAT1-TERT fusions are uniquely recurrent in epithelioid trophoblastic tumors and positively regulate cell growth

Gestational trophoblastic disease (GTD) is a heterogeneous group of lesions arising from placental tissue. Epithelioid trophoblastic tumor (ETT), derived from chorionic-type trophoblast, is the rarest form of GTD with only approximately 130 cases described in the literature. Due to its morphologic mimicry of epithelioid smooth muscle tumors and carcinoma, ETT can be misdiagnosed. To date, molecular characterization of ETTs is lacking. Furthermore, ETT is difficult to treat when disease spreads beyond the uterus. Here using RNA-Seq analysis in a cohort of ETTs and other gestational trophoblastic lesions we describe the discovery of LPCAT1-TERT fusion transcripts that occur in ETTs and coincide with underlying genomic deletions. Through cell-growth assays we demonstrate that LPCAT1-TERT fusion proteins can positively modulate cell proliferation and therefore may represent future treatment targets. Furthermore, we demonstrate that TERT upregulation appears to be a characteristic of ETTs, even in the absence of LPCAT1-TERT fusions, and that it appears linked to copy number gains of chromosome 5. No evidence of TERT upregulation was identified in other trophoblastic lesions tested, including placental site trophoblastic tumors and placental site nodules, which are thought to be the benign chorionic-type trophoblast counterpart to ETT. These findings indicate that LPCAT1-TERT fusions and copy-number driven TERT activation may represent novel markers for ETT, with the potential to improve the diagnosis, treatment, and outcome for women with this rare form of GTD.

Dysregulation of Placental Functions and Immune Pathways in Complete Hydatidiform Moles

Gene expression studies of molar pregnancy have been limited to a small number of candidate loci. We analyzed high-dimensional RNA and protein data to characterize molecular features of complete hydatidiform moles (CHMs) and corresponding pathologic pathways. CHMs and first trimester placentas were collected, histopathologically examined, then flash-frozen or paraffin-embedded. Frozen CHMs and control placentas were subjected to RNA-Seq, with resulting data and published placental RNA-Seq data subjected to bioinformatics analyses. Paraffin-embedded tissues from CHMs and control placentas were used for tissue microarray (TMA) construction, immunohistochemistry, and immunoscoring for galectin-14. Of the 14,022 protein-coding genes expressed in all samples, 3,729 were differentially expressed (DE) in CHMs, of which 72% were up-regulated. DE genes were enriched in placenta-specific genes (OR = 1.88, p = 0.0001), of which 79% were down-regulated, imprinted genes (OR = 2.38, p = 1.54 × 10-6), and immune genes (OR = 1.82, p = 7.34 × 10-18), of which 73% were up-regulated. DNA methylation-related enzymes and histone demethylases were dysregulated. "Cytokine-cytokine receptor interaction" was the most impacted of 38 dysregulated pathways, among which 17 were immune-related pathways. TMA-based immunoscoring validated the lower expression of galectin-14 in CHM. In conclusion, placental functions were down-regulated, imprinted gene expression was altered, and immune pathways were activated, indicating complex dysregulation of placental developmental and immune processes in CHMs.

Maternal human telomerase reverse transcriptase variants are associated with preterm labor and preterm premature rupture of membranes

Objective

Premature aging and short telomere lengths of fetal tissues are associated with spontaneous preterm labor (PTL) and preterm premature rupture of membranes (pPROM). Maintenance of telomere length is performed by the enzyme telomerase. Human telomerase reverse transcriptase (hTERT) is a subunit of telomerase, and its dysfunction affects telomere shortening. This study assessed whether maternal or fetal genetic variations in the hTERT gene are associated with PTL or pPROM.

Methods

A case (PTL or pPROM) control (term birth) genetic association study was conducted in 654 non-Hispanic white mothers (438 term, 162 PTL, 54 pPROM) and 502 non-Hispanic white newborns (346 term, 116 PTB, 40 pPROM). Maternal and fetal DNA samples were genotyped for 23 single nucleotide polymorphisms (SNPs) within the hTERT gene. Allele frequencies were compared between cases and controls, stratified by PTL and pPROM. Maternal and fetal data were analyzed separately.

Results

Allelic differences in one SNP of hTERT (rs2853690) were significantly associated with both PTL (adjusted OR 2.24, 95%CI 1.64–3.06, p = 2.32e-05) and with pPROM (adjusted OR 7.54, 95%CI 3.96–14.33, p = 2.39e-07) in maternal DNA. There was no significant association between the hTERT SNPs analyzed and PTL or pPROM in the fetal samples.

Conclusion

hTERT polymorphisms in fetal DNA do not associate with PTL or pPROM risk; however, maternal genetic variations in hTERT may play a contributory role in risk of PTL and PPROM.

Telomerase activity in pregnancy complications (Review)

Telomeres are specific DNA regions positioned at the ends of chromosomes and composed of functional non-coding repeats. Upon cell division, the telomeres decrease in length by a preordained amount. When the telomeres become critically short, cells lose the ability to divide and enter a specific functioning mode designated as 'cellular senescence'. However, human tissues express an enzyme that deters the shrinking of the telomeres, the telomerase. Due to its ability to maintain telomere length, the telomerase slows down and possibly suspends the aging of the cells. In regard to this, solid evidence demonstrates that female human fertility decreases with increased maternal age and that various adverse factors, including alterations in telomerase activity, can contribute to age-associated infertility in women. The fact that telomerase activity is regulated in a time- and location-dependent manner in both embryo and placental tissues, highlights it potential importance to the successful completion of pregnancy. Since maternal age is a crucial determining factor for the success of in vitro and in vivo fertilization, numerous studies have focused on telomerase activity and its correlation with mammalian fertilization, as well as the following cleavage and pre-implantation developmental processes. Associations between telomerase activity and pregnancy complications have been previously observed. Our aim in this review was to summarize and critically discuss evidence correlating telomerase activity with pregnancy complications.

The status of telomerase enzyme activity in benign and malignant gynaecologic pathologies

BACKGROUND

Telomeres are essential for the function and stability of eukaryotic chromosomes. Telomerase consists of three subunits: human telomerase reverse transcriptase (hTERT), human telomerase RNA (hTR), and telomerase protein 1 (TP1). The hTERT subunit determines the activity of telomerase as an enzyme and is detected in most human tumors and regenerative cells. Telomerase activity is a useful cancer-cell detecting marker in some types of cancers.

AIMS

The aim of this study was to assess of telomerase hTERT mRNA in gynaecological tumors for diagnosis of malignancy.

STUDY DESIGN

Cross-sectional study.

METHODS

A total of 55 gynaecologic tumor samples (35 ovarian, 13 endometrial, 6 cervical and 1 placental site trophoblastic tumor tissue) were obtained at the time of surgery. Quantification of hTERT mRNA was performed in a real-time reverse transcriptase polymerase chain reaction (RT-PCR) using the LightCycler TeloTAGGG hTERT Quantification Kit.

RESULTS

It was histopathologically detected that 18 of the tissue samples were malignant and 37 of the samples were benign. 16 of the malignant tissue samples (88.9%) and 3 (8.1%) (endometrial tissue in proliferative phase, mucinous cyst adenoma and endometriosis) of the benign tissue samples were found to be hTERT positive. With the presence of these data, sensitivity and specificity of hTERT for the diagnosis of malignancy were calculated to be 88.9% and 91.9%, respectively.

CONCLUSION

It was suggested that the measurement of telomerase activity in gynaecologic tumors, except for endometrial tissue in the reproductive phase, is a valuable method for pathological investigation.

The long and short of it: the role of telomeres in fetal origins of adult disease

Placental insufficiency, maternal malnutrition, and other causes of intrauterine growth restriction (IUGR) can significantly affect short-term growth and long-term health. Following IUGR, there is an increased risk for cardiovascular disease and Type 2 Diabetes. The etiology of these diseases is beginning to be elucidated, and premature aging or cellular senescence through increased oxidative stress and DNA damage to telomeric ends may be initiators of these disease processes. This paper will explore the areas where telomere and telomerase biology can have significant effects on various tissues in the body in IUGR outcomes.

Telomerase and apoptosis in the placental trophoblasts of growth discordant twins

In an effort to investigate the molecular basis of growth discordance in embryos that experience the same uterine environment, we compared telomerase activity and apoptosis in placental trophoblasts obtained from growth discordant twins. Between January 2003 and February 2005, placental tissue from twenty pairs of twins was obtained within thirty minutes of delivery. Eleven cases were classified as growth discordant, with birth weight discordance greater than 20%. Nine cases comprised the control group, with less than 20% discordance. Telomerase and apoptotic activities in placental trophoblasts were analyzed by ELISA and immunoblot. Statistical significance was analyzed by a paired t-test, chi- squared test, and ANOVA (SPSS ver 11.0). The average growth discordance was 26.8% in the growth discordant group and 14.4% in the control group. There were no significant differences in maternal age, week of gestation at delivery, parity, or chorionisity between the two groups. In the growth discordant group, the larger twin showed significantly higher telomerase activity (p < 0.01), whereas no significant difference was observed in the control group (p = 0.36). In addition, there was no definitive correlation between telomerase activity and the degree of growth discordance in the larger or smaller twins (R = -0.521 and -0.399, p = 0.15 and 0.25, respectively). The apoptosis proteins Bax and Bcl 2 were detected in both the larger and smaller twins in the growth discordant and control groups. There was no statistically significant difference in Bax expression between the larger and smaller twins (p = 0.25 and 0.92, respectively) for either the growth discordant or the control groups. Bcl 2 expression also showed no significant difference between groups. In conclusion, a tendency toward reduced telomerase activity and increased apoptosis was discovered in placental trophoblasts of the smaller growth- discordant twin, possibility resulting in delayed fetal growh.

Regulation of growth and function of the human placenta

The human placenta is a tumor-like tissue in which highly proliferative, migratory, and invasive extra-villous trophoblast cells, migrate and invade the uterus and its vasculature, to provide a vital link between the mother and the developing fetus. In the present article, we review our studies on a series of experiments, designed to identify molecular events responsible for the phenotypic changes during placental growth. Our observations illustrate that the human placenta is endowed with the biochemical machinery to proliferate indefinitely throughout gestation, yet, there are intrinsic mechanisms that effectively circumscribe the extent and duration of trophoblast proliferation. The placenta combines in itself the unique ability to produce a wide variety of protein, peptide and steroid hormones, but intricately interwoven in this process, is also the remarkable capacity to simultaneously regulate their synthesis and secretion. The placenta therefore represents an autonomous or a self-sufficient unit capable of modulating its own growth and function, while assisting the developing fetus until it is capable of independent existence.

Hypoxia-inducible factor 1 mediates upregulation of telomerase (hTERT)

Hypoxia occurs during the development of the placenta in the first trimester and correlates with both trophoblast differentiation and the induction of telomerase activity through hTERT expression. We sought to determine the mechanism of regulation of hTERT expression during hypoxia. We show that hypoxia-inducible factor 1alpha (HIF-1alpha) and hTERT expression in the human placenta decrease with gestational age and that these are overexpressed in preeclamptic placenta, a major complication of pregnancy. Hypoxia not only transactivates the hTERT promoter activity but also enhances endogenous hTERT expression. The hTERT promoter region between -165 and +51 contains two HIF-1 consensus motifs, and in vitro reporter assays show that these are essential for hTERT transactivation by HIF-1. Introduction of an antisense oligonucleotide for HIF-1 diminishes hTERT expression during hypoxia, indicating that upregulation of hTERT by hypoxia is directly mediated through HIF-1. Our results provide persuasive evidence that the regulation of hTERT promoter activity by HIF-1 represents a mechanism for trophoblast growth during hypoxia and suggests that this may be a generalized response to hypoxia in various human disorders including resistance to cancer therapeutics by upregulating telomerase.

Establishment and characterization of a new human cell line (EJ) derived from endometrial carcinoma

We present a new cell line, EJ established from an invasive endometrioid adenocarcinoma of the uterine corpus in a 56-year-old patient. The cells show rapid growth in culture with a doubling time of 16 h and high migration activity. Monolayer-cultured cells were polygonal in shape showing a tendency to pile up without contact inhibition. Subcutaneous transplantation of the EJ cells into nude mice formed solid tumors that were histologically diagnosed as adenocarcinoma, whereas no metastasis was observed. Cultured EJ cells produced tissue polypeptide antigen (IPA). Genetic and molecular analyses revealed high telomerase activity but not estrogen receptor alpha expression. Using the DNA sequencing technique, we have screened EJ cells for p53 mutation in exon 5 to 8 but no mutation of p53 was observed. This cell line appears to represent the development of a more malignant clone with divergent receptor function and growth behavior, and provides us with an interesting new tool for the study of tumorigenesis in the human endometrium.