Genetics of gestational trophoblastic neoplasia: an update for the clinician

ATR and CDK4/6 inhibition target the growth of methotrexate-resistant choriocarcinoma

Low-risk gestational trophoblastic neoplasia including choriocarcinoma is often effectively treated with Methotrexate (MTX) as a first line therapy. However, MTX resistance (MTX-R) occurs in at least ≈33% of cases. This can sometimes be salvaged with actinomycin-D but often requires more toxic combination chemotherapy. Moreover, additional therapy may be needed and, for high-risk patients, 5% still die from the multidrug-resistant disease. Consequently, new treatments that are less toxic and could reverse MTX-R are needed. Here, we compared the proteome/phosphoproteome of MTX-resistant and sensitive choriocarcinoma cells using quantitative mass-spectrometry to identify therapeutically actionable molecular changes associated with MTX-R. Bioinformatics analysis of the proteomic data identified cell cycle and DNA damage repair as major pathways associated with MTX-R. MTX-R choriocarcinoma cells undergo cell cycle delay in G1 phase that enables them to repair DNA damage more efficiently through non-homologous end joining in an ATR-dependent manner. Increased expression of cyclin-dependent kinase 4 (CDK4) and loss of p16^Ink4a in resistant cells suggested that CDK4 inhibition may be a strategy to treat MTX-R choriocarcinoma. Indeed, inhibition of CDK4/6 using genetic silencing or the clinically relevant inhibitor, Palbociclib, induced growth inhibition both in vitro and in an orthotopic in vivo mouse model. Finally, targeting the ATR pathway, genetically or pharmacologically, re-sensitised resistant cells to MTX in vitro and potently prevented the growth of MTX-R tumours in vivo. In short, we identified two novel therapeutic strategies to tackle MTX-R choriocarcinoma that could rapidly be translated into the clinic.

Prediction of Neoplastic Transformation of Hydatidiform Mole: Current Evidence

Gestational trophoblastic disease is not an uncommonly encountered pathology in clinical practice. The rate of post-molar neoplastic transformation is around 5-20% with higher rates after complete versus partial molar pregnancies. Recently, a role for molecular and genetic markers in the prediction of neoplastic transformation has emerged. We read with interest the article by St. Laurent et al. published in this issue of Reproductive Sciences. The authors compared miRNA profiles between complete hydatidiform moles (CHMs) and pre-gestational trophoblastic neoplasia CHM samples at three distinct tropho-miRNA clusters, 14q32, C19MC, and miR-371-3, as well as the expression of the contiguous DLK1, DIO3, and RTL1 genes. They found significant differences in expression of the 14q32 miRNA cluster and a fivefold decrease in protein expression of DIO3 but no difference in DIO3 mRNA expression. We reviewed the literature for similar studies looking at predictive tools for neoplastic transformation. We encourage future randomized controlled trials using these 2 novel risk predictors postulated by St. Laurent et al. to validate and guide future prophylactic chemotherapy for prevention of post-molar GTN.

A Review on the Pathogenesis and Clinical Management of Placental Site Trophoblastic Tumors

Placental site trophoblastic tumor (PSTT) is a rare type of gestational trophoblastic disease originating from the intermediate trophoblast. Compared with hydatidiform mole, invasive hydatidiform mole and choriocarcinoma, the diagnosis of PSTT is more complicated and lacks specific and sensitive tumor markers. Most PSTT patients demonstrate malignant potential, and the primary treatment of PSTT is hysterectomy. However, metastasis occasionally occurs and even causes death in a small number of PSTT patients. Most PSTT patients are young women hence fertility preservation is an important consideration. The major obstacle for PSTT patient prognosis is chemotherapy resistance. However, the current understanding of the pathogenesis of PSTT and clinical treatment remains elusive. In this review, we summarized the research progress of PSTT in recent years from three aspects: mechanism, clinical presentation, and treatment and prognosis. Well-conducted multi-center studies with sufficient sample sizes are of great importance to better examine the pathological progress and evaluate the prognosis of PSTT patients, so as to develop prevention and early detection programs, as well as novel treatment strategies, and finally improve prognosis for PSTT patients.

A metastatic invasive mole arising from iatrogenic uterus perforation

Background

Invasive mole derives from hydatidiform mole, but its pathogenesis remains unknown. Invasive mole arising from iatrogenic uterine perforation has not been reported yet.

Case presentation

A reproductive woman was admitted because she suffered form severe abdominal pain and acute intra-abdominal hemorrhage after suction evacuation due to misdiagnosis as inevitable abortion. The patient underwent hysteroscopy and laparoscopy, by which an iatrogenic uterine perforation and omentum and pelvic peritoneum metastases were confirmed. All lesions were removed and the final pathological diagnosis was metastatic invasive mole. The patient underwent post-operative chemotherapy with methotrexate and presented a good prognosis.

Conclusion

Invasive mole arising form iatrogenic uterine perforation displays an unusual metastatic manner other than general invasive moles. The prevention of uterine perforation should be emphasized during suction evacuation for mole pregnancy.

FBI-1 Is Overexpressed in Gestational Trophoblastic Disease and Promotes Tumor Growth and Cell Aggressiveness of Choriocarcinoma via PI3K/Akt Signaling

Human placental trophoblasts can be considered pseudomalignant, with tightly controlled proliferation, apoptosis, and invasiveness. Gestational trophoblastic disease (GTD) represents a family of heterogeneous trophoblastic lesions with aberrant apoptotic and proliferative activities and dysregulation of cell signaling pathways. We characterize the oncogenic effects of factor that binds to the inducer of short transcripts of HIV-1 [FBI-1, alias POZ and Krüppel erythroid myeloid ontogenic factor (POKEMON)/ZBTB7A] in GTD and its role in promoting cell aggressiveness in vitro and tumor growth in vivo. IHC studies showed increased nuclear expression of FBI-1, including hydatidiform moles, choriocarcinoma (CCA), and placental site trophoblastic tumor, in GTD. In JAR and JEG-3 CCA cells, ectopic FBI-1 expression opposed apoptosis through repression of proapoptotic genes (eg, BAK1, FAS, and CASP8). FBI-1 overexpression also promoted Akt activation, as indicated by Akt-pS473 phosphorylation. FBI-1 overexpression promoted mobility and invasiveness of JEG-3 and JAR, but not in the presence of the phosphoinositide 3-kinase inhibitor LY294002. These findings suggest that FBI-1 could promote cell migration and invasion via phosphoinositide 3-kinase/Akt signaling. In vivo, nude mice injected with CCA cells with stable FBI-1 knockdown demonstrated reduced tumor growth compared with that in control groups. These findings suggest that FBI-1 is clinically associated with the progression of, and may be a therapeutic target in, GTD, owing to its diverse oncogenic effects on dysregulated trophoblasts.

Crosstalk between the p38 and TGF-β signaling pathways through TβRI, TβRII and Smad3 expression in plancental choriocarcinoma JEG-3 cells

Choriocarcinoma is a highly aggressive tumor that develops from germ cells. Some choriocarcinomas originate in the testes or ovaries, while others may develop in the uterus after a normal pregnancy or after miscarriage. The tumor is characterized by early hematogenous spread to distal organs, such as the lung and brain. Transforming growth factor β1 (TGF-β1) is key in regulating tumor cell proliferation and invasion through a variety of Smad-dependent and -independent pathways, including the p38 mitogen-activated protein kinase (MAPK) pathway. There appears to be crosstalk between the TGF-β/Smad and p38 MAPK pathways; however, the molecular mechanisms underlying the crosstalk are not fully understood. The present study validated the role of TGF-β signaling in cancer progression and explored the interaction between Smad and p38 MAPK signaling on transduction mediators in choriocarcinoma using the JEG-3 cell line. MTT assay was used to detect the effect of TGF-β1 on JEG-3 cell proliferation. Cells were treated with p38 MAPK inhibitor and TGF-β receptor inhibitor, followed by TGF-β1, and reverse transcription quantitative real-time polymerase chain reaction was used to examine the transcriptional levels of Smad3 and TGF-β receptors. The data demonstrated that TGF-β can enhance the viability of JEG-3 cells. Blockade of the TGF-β and p38 MAPK pathways attenuated the expression of Smad3, TGF-β receptor type I (TβRI) and TβRII, and inhibited their expression in a dose-dependent manner. Analysis revealed that p38 MAPK is involved in and contributes to the TGF-β pathway, dependent on the regulation of TβRI, TβRII and Smad3. Further investigation of the interactions between the TGF-β and p38 MAPK pathways may offer potential venues for therapeutic intervention for choriocarcinoma.