Establishment and characterization of cell lines derived from complete hydatidiform mole

Elucidation of the role of XBP1 in the progression of complete hydatidiform mole to invasive mole through RNA-seq

OBJECTIVE

A complete hydatidiform mole (CHM) is a common disease and is known to develop post-molar gestational trophoblast neoplasia (GTN). However, the molecular mechanisms underlying the progression of CHM to post-molar GTN remain largely unknown. In this study, we investigated the molecular factors associated with the progression using RNA-seq.

METHODS

We included 13 patients with CHM and performed RNA-seq using freshly frozen samples. We identified differentially expressed genes between patients who developed GTN (GTN group) and those who achieved spontaneous remission after uterine evacuation (SR group), and performed pathway analysis. Then, functional analyses were performed on choriocarcinoma (JAR and JEG-3) and CHM (Hmol1-3B and Hmol1-2C) cells. Moreover, we evaluated the in vivo tumorigenicity of XBP1-overexpressed Hmol1-3B cells.

RESULTS

The gene expression profiles were separated into two groups, and an upstream regulator analysis was performed using 281 differentially expressed genes. We focused on transcription factors and identified that 33 transcription factors were activated in the GTN group. Then, excluding those with low expression levels in clinical samples and cell lines, XBP1 was selected for further analysis. Additionally, XBP1 downregulation significantly decreased the migration and invasive abilities of choriocarcinoma cells, whereas XBP1 overexpression significantly increased the migration and invasive abilities of CHM cells. Furthermore, animal experiments showed that tumor weight and blood human chorionic gonadotropin (hCG) levels were significantly higher in the XBP1-overexpressing Hmol1-3B-bearing mice than those in the control mice.

CONCLUSION

RNA-seq identified XBP1 as a key factor in post-molar GTN, suggesting it contributes to the development of post-molar GTN.

Epidemiologic study on gestational trophoblastic diseases in Japan

Objective

This study aims to estimate the population-based incidence of gestational trophoblastic diseases (GTDs) and to identify the characteristics of gestational trophoblastic neoplasia (GTN) in Japan.

Methods

The annual number of GTD and live births from 1974 to 2018 were used to estimate the incidence of GTD. The data of 1,574 GTN cases from 1999 to 2018 were analyzed to identify the characteristics of low-risk GTN, high-risk GTN, placental site trophoblastic tumor (PSTT), and epithelioid trophoblastic tumor (ETT).

Results

The incidence of hydatidiform mole was 2.02 per 1,000 live births on average which decreased from 1974 to 2008 and increased from 2009 to 2018. The incidence of low-risk GTN, high-risk GTN, PSTT, and ETT was 15.3, 3.5, 0.3, and 0.07 per 100,000 live births, respectively. The estimated incidence of post-molar GTN was 9.8% of molar patients. High-risk GTN was diagnosed more pathologically, had more various kinds of antecedent pregnancies, and had longer intervals after the antecedent pregnancy compared to low-risk GTN. Furthermore, 8.2% of high-risk GTN occurred after the subsequent non-molar pregnancy of hydatidiform mole. The cumulative percentage of developing high-risk GTN after hydatidiform mole reached 89.3% at the 60th month.

Conclusion

The incidence of hydatidiform mole, low-risk GTN, high-risk GTN was 2.02 per 1,000 live births, 15.3 per 100,000 live births, and 3.5 per 100,000 live births, respectively. High-risk GTN was diagnosed more pathologically and later after the antecedent pregnancy than low-risk GTN. Following molar patients for five years is needed to improve the mortality of malignant GTN.

The incidence of hydatidiform mole and gestational trophoblastic neoplasia (GTN) in Japan was estimated. The incidence of post-molar GTN was stable at approximately 10%. Of high-risk GTN, 8.2% occurred after the subsequent non-molar pregnancy of hydatidiform mole. Following molar patients for 5 year is necessary for early diagnosis of high-risk GTN.

Derivation of human triploid trophoblast stem cells

PURPOSE

Human trophoblast stem cells (hTSCs) are counterparts of the precursor cells of the placenta and are valuable cell models for the study of placental development and the pathogenesis of placental diseases. The aim of this work was to establish a triploid human TSC (hTSC^3PN) derived from the tripronuclear embryos, which are clinically discarded but readily available, for potential applications in basic placental research and disease modeling.

METHODS

Eighteen tripronuclear human zygotes from IVF were collected and cultured for 5-6 days. Five high-quality blastocysts were harvested and were individually cultured in hTSC medium. Finally, two hTSC lines were established after 10 days and could be passaged stably.

RESULTS

The karyotyping analysis showed that hTSC^3PN contained three sets of chromosomes. And the hTSC^3PN exhibited typical features of hTSCs, with the ability to differentiate into two trophoblast lineages: extravillous cytotrophoblasts (EVTs) and syncytiotrophoblasts (STs). In addition, the hTSC^3PN can mimic some vital features of trophoblast, including hormone secretion and invasion. Further studies showed that the proliferation and differentiation of hTSC^3PN were reduced compared with normal hTSCs, which may be related to the disturbed metabolic signaling in hTSC^3PN.

CONCLUSIONS

We established the triploid hTSC lines derived from tripronuclear embryos, which provides a potentially useful research model in vitro to study human placental biology and diseases.

Transfection types, methods and strategies: a technical review

Transfection is a modern and powerful method used to insert foreign nucleic acids into eukaryotic cells. The ability to modify host cells' genetic content enables the broad application of this process in studying normal cellular processes, disease molecular mechanism and gene therapeutic effect. In this review, we summarized and compared the findings from various reported literature on the characteristics, strengths, and limitations of various transfection methods, type of transfected nucleic acids, transfection controls and approaches to assess transfection efficiency. With the vast choices of approaches available, we hope that this review will help researchers, especially those new to the field, in their decision making over the transfection protocol or strategy appropriate for their experimental aims.

MiR-30a-5p inhibits proliferation and metastasis of hydatidiform mole by regulating B3GNT5 through ERK/AKT pathways

Hydatidiform moles are gestational trophoblastic disease. They are abnormal proliferations of trophoblast cells that have the potential to become cancerous. miR-miR30a-5p is a tumour suppressor that participates in the development of numerous diseases. However, the role of miR-30a in hydatidiform moles and the mechanisms underlying its effects are presently unclear. This study explored the levels of miR-30a and B3GNT5 expression in human hydatidiform mole tissue. The results showed that miR-30a and B3GNT5 were differentially expressed in normal placenta and hydatidiform mole, and miR-30a decreased cell proliferation, invasion and migration in trophoblast cell lines. Upon further examination, it was confirmed that miR-30a directly targeted the 3'untranslated region of B3GNT5 using a dual-luciferase assay. The results of the present study also revealed that miR-30a reduced the proliferation, invasion and migration ability in JAR and BeWo cells by regulating B3GNT5, which may inactivate the ERK and AKT signalling pathways. This study demonstrated that miR-30a was a novel target B3GNT5 that serves an important role in the development of hydatidiform moles, suggesting that miR-30a may serve as a novel potential biomarker or useful diagnostic and therapeutic tool for hydatidiform moles in clinical settings.

Evaluation of a routine second curettage for hydatidiform mole: a cohort study

OBJECTIVE

The aim of this study was to evaluate routine second curettage for hydatidiform mole (HM) by comparing the characteristics and outcomes of developing gestational trophoblastic neoplasia (GTN).

STUDY DESIGN

This was a cohort study including 173 patients diagnosed with HM between January 2002 and August 2019 who were followed up at Nagoya University Hospital, Japan. After an evacuation, 105 and 68 patients were managed with the routine method (routine group) and elective method (elective group) for a second curettage, respectively. The routine second curettage was performed around 7 days after the first evacuation. Patients in the elective group underwent a second curettage if there was ultrasonographic evidence of molar remnants in the uterine cavity. Socio-clinical factors were retrospectively compared between the routine and elective groups, and between patients showing regression and those who developed GTN.

RESULTS

The incidence of GTN was 15.2% in the routine group and 20.6% in the elective group, and the difference was not significant (P = 0.364). The median GTN risk score was significantly higher in the routine group than in the elective group (P = 0.033). Presence of a complete HM, gestational age, and a pre-treatment human chorionic gonadotropin level of ≥ 200,000 mIU/mL were independent risk factors for GTN in molar patients.

CONCLUSION

The incidence of GTN was unchanged but the risk score of GTN was higher in the routine group than in the elective group. Routine second curettage may not be necessary, but further study will be needed to confirm this.

Loss of p57KIP2 expression confers resistance to contact inhibition in human androgenetic trophoblast stem cells

Complete hydatidiform moles (CHMs) develop from androgenetic conceptuses and are characterized by enhanced proliferation of trophoblast cells and a significantly higher risk of trophoblast tumors. Loss of the maternal genome and duplication of the paternal genome are considered to be responsible for the phenotype, but the detailed mechanism remains unclear. Here, we report the derivation of trophoblast stem (TS) cells from CHMs. These cells have reduced sensitivity to contact inhibition of cell proliferation and exhibit aberrant expression of imprinted genes, which are expressed from only 1 parental allele. We also reveal that the maternally expressed imprinted gene p57^KIP2 would be responsible for the enhanced proliferation of CHM-derived TS cells. Our findings provide an insight into the pathogenesis of CHMs.

A complete hydatidiform mole (CHM) is androgenetic in origin and characterized by enhanced trophoblastic proliferation and the absence of fetal tissue. In 15 to 20% of cases, CHMs are followed by malignant gestational trophoblastic neoplasms including choriocarcinoma. Aberrant genomic imprinting may be responsible for trophoblast hypertrophy in CHMs, but the detailed mechanisms are still elusive, partly due to the lack of suitable animal or in vitro models. We recently developed a culture system of human trophoblast stem (TS) cells. In this study, we apply this system to CHMs for a better understanding of their molecular pathology. CHM-derived TS cells, designated as TS^mole cells, are morphologically similar to biparental TS (TS^bip) cells and express TS-specific markers such as GATA3, KRT7, and TFAP2C. Interestingly, TS^mole cells have a growth advantage over TS^bip cells only after they reach confluence. We found that p57^KIP2, a maternally expressed gene encoding a cyclin-dependent kinase inhibitor, is strongly induced by increased cell density in TS^bip cells, but not in TS^mole cells. Knockout and overexpression studies suggest that loss of p57^KIP2 expression would be the major cause of the reduced sensitivity to contact inhibition in CHMs. Our findings shed light on the molecular mechanism underlying the pathogenesis of CHMs and could have broad implications in tumorigenesis beyond CHMs because silencing of p57^KIP2 is frequently observed in a variety of human tumors.