The Lin28/Let-7 System in Early Human Embryonic Tissue and Ectopic Pregnancy

Abstract

Our objective was to determine the expression of the elements of the Lin28/Let-7 system, and related microRNAs (miRNAs), in early stages of human placentation and ectopic pregnancy, as a means to assess the potential role of this molecular hub in the pathogenesis of ectopic gestation. Seventeen patients suffering from tubal ectopic pregnancy (cases) and forty-three women with normal on-going gestation that desired voluntary termination of pregnancy (VTOP; controls) were recruited for the study. Embryonic tissues were subjected to RNA extraction and quantitative PCR analyses for LIN28B, Let-7a, miR-132, miR-145 and mir-323-3p were performed. Our results demonstrate that the expression of LIN28B mRNA was barely detectable in embryonic tissue from early stages of gestation and sharply increased thereafter to plateau between gestational weeks 7–9. In contrast, expression levels of Let-7, mir-132 and mir-145 were high in embryonic tissue from early gestations (≤6-weeks) and abruptly declined thereafter, especially for Let-7. Opposite trends were detected for mir-323-3p. Embryonic expression of LIN28B mRNA was higher in early stages (≤6-weeks) of ectopic pregnancy than in normal gestation. In contrast, Let-7a expression was significantly lower in early ectopic pregnancies, while miR-132 and miR-145 levels were not altered. Expression of mir-323-3p was also suppressed in ectopic embryonic tissue. We are the first to document reciprocal changes in the expression profiles of the gene encoding the RNA-binding protein, LIN28B, and the related miRNAs, Let-7a, mir-132 and mir-145, in early stages of human placentation. This finding suggests the potential involvement of LIN28B/Let-7 (de)regulated pathways in the pathophysiology of ectopic pregnancy in humans.

Deregulation of miR-324/KISS1/kisspeptin in early ectopic pregnancy: mechanistic findings with clinical and diagnostic implications

“…The present study was approved by the Institutional Review Board/Independent Ethics Committee of the Hospital Universitario La Fe, Valencia, Spain. Early embryonic tissue (mostly trophoblast) was collected after obtaining the corresponding informed consent from each patient, as described elsewhere (28,29).…”

“…A total of 108 women with a normal ongoing pregnancy that desired a voluntary termination of pregnancy (VTOP) and 45 patients suffering from tubal ectopic pregnancy were recruited, following previous described criteria (28,29). All individuals (EP and VTOP) included in this study signed an informed consent, and samples were properly dated according to the last menstrual period (week of pregnancy).…”

“…MiRNAs are small, non-coding RNAs that can modulate (mainly repress) gene/protein expression, primarily via interaction with seed regions at the 3' untranslated region (3'-UTR) of target genes, thereby promoting mRNA degradation or Kisspeptin and miR-324-3p in Ectopic Pregnancy preventing protein translation (26). Deregulation of miRNA expression in embryonic/ placental tissues and the fallopian tube has been reported in EP (27)(28)(29). These studies have surfaced changes in the expression patterns of miRNAs of the let7 family, as well as mir-132, miR-145, miR149, miR-182, miR-196, miR-223, and miR-424 in ectopic implantation; yet, the putative mechanistic implications for these alterations are yet to be elucidated.…”

Pregnancy-associated microRNAs in plasma as potential molecular markers of ectopic pregnancy

“…In consequence, the small sample size in our study and other studies may be the reason for the discrepancy regarding circulating levels of cell-free miR-323-3p among the studies (4,21). A larger study is necessary to determine whether cell-free miR-323-3p is a universal biomarker for the identification of EP (4).…”

“…Furthermore, Lozoya et al (21) reported that the expression of miR-323-3p is lower in EP tissues than in normal human embryonic tissues at 7 to 9 weeks of gestation. Our…”