Expression of human telomerase reverse transcriptase, the catalytic subunit of telomerase, is associated with the development of persistent disease in complete hydatidiform moles

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.

Pathogenesis of choriocarcinoma: clinical, genetic and stem cell perspectives

Choriocarcinoma is a unique malignant neoplasm composed of mononuclear cytotrophoblasts and multinucleated syncytiotrophoblasts that produce human chorionic gonadotrophin. Choriocarcinoma can occur after a pregnancy, as a component of germ cell tumors, or in association with a poorly differentiated somatic carcinoma, each with distinct clinical features. Cytogenetic and molecular studies, predominantly on gestational choriocarcinoma, revealed the impact of oncogenes, tumor suppressor genes and imprinting genes on its pathogenesis. The role of stem cells in various types of choriocarcinoma has been studied recently. This review will discuss how such knowledge can enhance our understanding of the pathogenesis of choriocarcinoma, enable exploration of novel anti-choriocarcinoma targeted therapy and possibly improve our insight on embryological and placental development.

Estrogen and progesterone receptors and telomerase enzyme immunohistochemical detection in gestational trophoblastic tumors

The purpose of this study is to evaluate the immunohistochemical detection of telomerase enzyme and estrogen receptor (ER) and progesterone receptor (PGR) in gestational trophoblastic neoplasia (GTN) and its clinical significance. Formalin-fixed paraffin blocks for 30 patients (24 with molar pregnancy, 3 with choriocarcinoma, and 3 with placental site trophoblastic tumor) as cases and six products of conception samples from patients with incomplete abortion as controls were included in the study. Immunohistochemical detection of the telomerase catalytic protein and ER and PGR was carried out using streptavidin-biotin-peroxidase method. All control tissues were negative for telomerase and ER expression, while five of six were PGR positive. Significant positive telomerase expression was detected in all gestational trophoblastic tumors (three of six partial moles, 12 of 18 complete moles, three of three choriocarcinomas, and two of three placental site trophoblastic tumors). Nine of 24 molar pregnancies were followed by GTN. Molar pregnancies followed by GTN were associated with higher serum beta-hCG (human chorionic gonadotrophic hormone), larger uterine size for gestational age, negative ER expression, negative PGR expression, and positive telomerase expression. All patients with molar pregnancy with negative telomerase expression (9 of 24) showed spontaneous regression after evacuation. Positive telomerase expression and its immunohistochemical detection are associated with the development of GTN. Negative telomerase expression is highly predictive of postmolar spontaneous regression. Patients with molar pregnancies with negative telomerase expression can be saved the long-term follow-up. ER and PGR expression do not show a significantly different pattern in molar tissues, while negative expression is associated with developing GTN. Cautions on the use of postmolar hormonal contraception may be unjustified.

The changes of gene expression profiles in hydatidiform mole and choriocarcinoma with hyperplasia of trophoblasts

The purpose of this study is to investigate changes of gene expression profiles in hydatidiform moles (HM) and choriocarcinoma and to explore causes of trophoblastic hyperplasia. Using cDNA microarray, 4,096 genes were analyzed in two pairs of the tissues of HM versus normal villi and in two pairs of normal primary culture trophoblasts versus JAR cell line of choriocarcinoma. The expressions of two genes in normal villi and HM, as well as in JAR and JEG-3, were examined with the help of immunohistochemistry, immunoblot, and reverse transcriptase-polymerase chain reaction in order to confirm the findings of cDNA microarray. Twenty-four genes were upregulated and 65 genes were downregulated in all HM. Four hundred thirty-three genes were upregulated and 380 genes were downregulated in JAR. Forty-six genes were upregulated in both HM and choriocarcinoma, whereas 13 genes were downregulated. Genes associated with the inhibition of cell proliferation were significantly downregulated, whereas genes associated with cell proliferation, malignant transformation, metastasis, and drug resistance were upregulated. Thymidine kinase-1 (TK-1) and small subunit ribonucleotide reductase (RRM-2) were overexpressed in HM, JAR, and JEG-3. The expressions of TK-1 and RRM-2 in moles were positively correlated with proliferative index of trophoblasts. Our results suggest that altered expression of genes exist in HM and choriocarcinoma. Trophoblastic hyperplasia may be involved in the overexpression of DNA synthetic enzymes.