Comparative genomic hybridization studies in hydatidiform moles and choriocarcinoma: amplification of 7q21-q31 and loss of 8p12-p21 in choriocarcinoma

Gestational trophoblastic disease: understanding the molecular mechanisms of placental tumours

Gestational trophoblastic disease (GTD) describes a group of rare benign and cancerous lesions originating from the trophoblast cells of the placenta. These neoplasms are unconventional entities, being one of the few instances in which cancer develops from the cells of another organism, the foetus. Although this condition was first described over 100 years ago, the specific genetic and non-genetic drivers of this disease remain unknown to this day. However, recent findings have provided valuable insights into the potential mechanisms underlying this rare condition. Unlike previous reviews focused primarily on the clinical and diagnostic aspects of disease development, this Review consolidates the latest research concerning the role of genetics, epigenetics and microRNAs in the initiation and progression of GTD. By examining GTD from a molecular perspective, this Review provides a unique framework for understanding the pathogenesis and progression of this rare disease.

Non-gestational choriocarcinoma: unraveling the similarities and distinctions from its gestational counterpart

Choriocarcinoma is a highly vascular and invasive tumor of anaplastic trophoblast, predominantly made up of cytotrophoblasts and syncytiotrophoblasts without villi. Based on its origin, choriocarcinoma can be either gestational or non-gestational. Non-gestational choriocarcinoma can be of germ cell origin, or can be seen in association with a somatic high-grade malignancy. It is difficult to differentiate gestational from non-gestational choriocarcinoma, especially in the reproductive age group. It is important to distinguish between the two, for accurate staging and prognostication, deciding the primary treatment modality, (ie, surgery or chemotherapy), and tailoring follow-up timeframes after diagnosis. An extensive literature search was performed regarding all cases of non-gestational choriocarcinoma, published before March 2023. A note was made of whether the origin of choriocarcinoma was ascertained and how gestational choriocarcinoma was differentiated from non-gestational choriocarcinoma. The keywords used for literature search were "non-gestational choriocarcinoma", "primary choriocarcinoma", "ovarian choriocarcinoma", "ovarian germ cell tumors", or "choriocarcinomatous differentiation". This review aims to summarize the similarities and differences in the epidemiology, pathogenesis, clinical presentation, and management guidelines between gestational and non-gestational choriocarcinoma, which can form an important educational resource for clinicians and laboratory physicians dealing with such cases.

Genetics of gestational trophoblastic disease

The abnormal pregnancies complete and partial hydatidiform mole are genetically unusual, being associated with two copies of the paternal genome. Typical complete hydatidiform moles (CHMs) are diploid and androgenetic, while partial hydatidiform moles (PHMs) are diandric triploids. While diagnosis can usually be made on the basis of morphology, ancillary techniques that exploit their unusual genetic origin can be used to facilitate diagnosis. Genotyping and p57 immunostaining are now routinely used in the differential diagnosis of complete and partial hydatidiform moles, for investigating unusual mosaic or chimeric products of conception with a molar component and identifying the rare diploid, biparental HMs associated with an inherited predisposition to molar pregnancies. Genotyping also plays an important role in the differential diagnosis of gestational and non-gestational trophoblastic tumours and identification of the causative pregnancy where tumours are gestational. Recent developments include the use of cell-free DNA for non-invasive diagnosis of these conditions.

Distinct genomic profiles of gestational choriocarcinoma, a unique cancer of pregnant tissues

Little is known about genomic alterations of gestational choriocarcinoma (GC), unique cancer that originates in pregnant tissues, and the progression mechanisms from the nonmalignant complete hydatidiform mole (CHM) to GC. Whole-exome sequencing (20 GCs) and/or single-nucleotide polymorphism microarray (29 GCs) were performed. We analyzed copy-neutral loss-of-heterozygosity (CN-LOH) in 29 GCs that exhibited androgenetic CN-LOHs (20 monospermic, 8 dispermic) and no CN-LOH (one with NLRP7 mutation). Most GCs (25/29) harboring recurrent copy number alterations (CNAs) and gains on 1q21.1-q44 were significantly associated with poor prognosis. We detected five driver mutations in the GCs, most of which were chromatin remodeling gene (ARID1A, SMARCD1, and EP300) mutations but not in common cancer genes such as TP53 and KRAS. One patient’s serial CHM/invasive mole/GC showed consistent CN-LOHs, but only the GC harbored CNAs, indicating that CN-LOH is an early pivotal event in HM-IM-GC development, and CNAs may be a late event that promotes CHM progression to GC. Our data indicate that GCs have unique profiles of CN-LOHs, mutations and CNAs that together differentiate GCs from non-GCs. Practically, CN-LOH and CNA profiles are useful for the molecular diagnosis of GC and the selection of GC patients with poor prognosis for more intensive treatments, respectively.

Genomic analysis reveals chromosomal alterations that drive disease progression in a poorly understood class of tumors that form in placental tissue. Gestational choriocarcinoma (GC) arises during pregnancy and can quickly develop into lethal metastatic disease if not treated promptly. To identify the origins of such malignancies, researchers led by Sug Hyung Lee and Yeun-Jun Chung at The Catholic University of Korea, Seoul, profiled genetic aberrations in 29 GC specimens. The researchers did not observe any consistent link between these malignancies and a particular set of ‘driver mutations’ underlying tumor progression as has been seen in other solid tumors. However, these GC samples exhibited striking levels of rearrangement between chromosomes. The researchers propose that the gain or loss of genes resulting from these chromosomal abnormalities may be an important contributor to rapidly progressing forms of this disease.

Tumour suppressor candidate 3 inhibits biological function and increases endoplasmic reticulum stress of melanoma cells WM451 by regulating AKT/GSK3-β/β-catenin pathway

Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. This study aims to evaluate the significance of TUSC3, an endoplasmic reticulum stress (ERS)-inducible gene and explore its relationship with AKT/GSK3-β/β-catenin signalling pathway in melanoma cell WM451. We investigated TUSC3 expression in melanoma cell by qRT-PCR, CCK-8 and clonal formation assays were utilized to evaluate cell proliferation. Wound healing and transwell experiments detected cell migration and invasion. Flow cytometry detected the level of apoptosis. Western blot analysed MMP2, MMP9, p-AKT, p-GSK3-β, β-catenin and AKT, GSK3-β, ERS-related proteins and apoptosis-related proteins in WM451 cells. The results revealed that TUSC3 was remarkably decreased in melanoma cell lines. Overexpression of TUSC3 significantly inhibits melanoma cell WM451 biological functions and promotes expression of ERS-related proteins in WM451 cells, increases ERS in WM451 cells by inhibiting AKT/GSK3-β/β-catenin pathway. These finding suggest that TUSC3 regulates biological functions of melanoma cells WM451 and increases ERS in melanoma cells WM451 via the inhibition of the AKT/GSK3-β/β-catenin signalling pathway. SIGNIFICANCE OF THE STUDY: Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. Therefore, studying the molecular mechanism of melanoma occurrence and metastasis is essential for the treatment of melanoma. Meanwhile, mounting studies suggest that TUSC3 is considered to be closely associated with the development of various malignancies. TUSC3 regulates proliferation, migration and epithelial-to-mesenchymal transition, but the molecular mechanism of the tumour suppressor effects of TUSC3 on melanoma cells is not well understood. Our study demonstrates that TUSC3 inhibits biological function of melanoma cells and increases ERS in melanoma cells by inhibiting AKT/GSK3-β/β-catenin pathway. And this is expected to be a new target and method for the treatment of melanoma.

Primary mediastinal choriocarcinoma in a female patient: Case report and review of the literature

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Primary mediastinal choriocarcinoma is rare, especially in female patients.

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Genomic losses predominated our case, which has not been previously reported.

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This tumor lacked human chorionic gonadotropin and required histologic diagnosis.

Endometrial Carcinoma With Trophoblastic Components: Clinicopathologic Analysis of a Rare Entity

Somatic endometrial carcinomas with trophoblastic components have only rarely been described. To better characterize this distinctive combination of histotypes, we report herein 4 new cases, representing the largest cohort reported thus far, and review previously reported cases. The 4 new patients ranged in age from 61 to 77 yr (mean, 68 yr). The first patient had a grade 2 endometrioid carcinoma, surgical International Federation of Gynecology and Obstetrics stage IA, that recurred 5 months later at the vaginal apex with purely choriocarcinoma elements, suggestive of unsampled trophoblastic areas in the uterus. The 3 other patients were all International Federation of Gynecology and Obstetrics stage III, and included 2 cases of dedifferentiated endometrial carcinoma with 40% and 20% choriocarcinoma components, and 1 case of grade 1 endometrioid carcinoma with a 40% choriocarcinoma component. Postoperative serum β-human chorionic gonadotropin was elevated in all patients. All received adjuvant combination chemotherapy, but all were dead of disease with distant metastases at an average of 11.75 mo (range, 7-16 mo) after primary staging. Data from our cases were combined with those from 24 cases that had previously been reported in the literature between 1972 and 2016. Analysis of this combined data indicates that endometrial carcinoma with trophoblastic component is a rare neoplasm that occurs primarily in postmenopausal patients. The trophoblastic component is most commonly a choriocarcinoma and the somatic component is most commonly an endometrioid carcinoma or an adenocarcinoma/carcinoma reported without further specification; the somatic component may be a diverse array of histotypes or histotype admixtures. Serum and/or urine β-human chorionic gonadotropin is elevated in almost all patients, and fluctuations of β-human chorionic gonadotropin generally correlated with tumor relapses or recurrences. The stage distribution and patient outcomes in the current and previously reported patients suggests that trophoblastic differentiation usually, but not invariably denotes clinical aggressiveness.

TUSC3: functional duality of a cancer gene

Two decades ago, following a systematic screening of LOH regions on chromosome 8p22, TUSC3 has been identified as a candidate tumor suppressor gene in ovarian, prostate and pancreatic cancers. Since then, a growing body of evidence documented its clinical importance in various other types of cancers, and first initial insights into its molecular function and phenotypic effects have been gained, though the precise role of TUSC3 in different cancers remains unclear. As a part of the oligosaccharyltransferase complex, TUSC3 localizes to the endoplasmic reticulum and functions in final steps of N-glycosylation of proteins, while its loss evokes the unfolded protein response. We are still trying to figure out how this mechanistic function is reconcilable with its varied effects on cancer promotion. In this review, we focus on cancer-related effects of TUSC3 and envisage a possible role of TUSC3 beyond endoplasmic reticulum.

[Cytogenomic studies of hydatiform moles and gestational choriocarcinoma]

The complete hydatidiform mole (CHM), a gestational trophoblastic disease, is usually caused by the development of an androgenic egg whose genome is exclusively paternal. Due to parental imprinting, only trophoblasts develop in the absence of a fetus. CHM are diploid and no abnormal karyotype is observed. It is 46,XX in most cases and less frequently 46,XY. The major complication of this disease is gestational choriocarcinoma, a metastasizing tumor and a true allografted malignancy. This complication is infrequent in developed countries, but is more common in the developing countries and is then worsened by delayed care. The malignancies are often accompanied by acquired, possibly etiological genomic abnormalities. We investigated the presence of recurrent cytogenetic abnormalities in CHM and post-molar choriocarcinoma using metaphasic CGH (mCGH) and high-resolution 244K aCGH techniques. The 10 CHM studied by mCGH showed no chromosomal gains or losses. For post-molar choriocarcinoma, 11 tumors, whose diagnosis was verified by histopathology, were investigated by aCGH. Their androgenic nature and the absence of tumor DNA contamination by maternal DNA were verified by the analysis of microsatellite markers. Three choriocarcinoma cell lines (BeWo, JAR and JEG) were also analyzed by aCGH. The results allowed us to observe some chromosomal rearrangements in primary tumors, and more in the cell lines. Chromosomal abnormalities were confirmed by FISH and functional effect by immunohistochemical analysis of gene expression. Forty minimum critical regions (MCR) were defined on chromosomes. Candidate genes implicated in choriocarcinoma oncogenesis were selected. The presence in the MCR of many miRNA clusters whose expression is modulated by parental imprinting has been observed, for example in 14q32 or in 19q13.4. This suggests that, in gestational choriocarcinoma, the consequences of gene abnormalities directly linked to acquired chromosomal abnormalities are superimposed upon those of imprinted genes altered at fertilization.

Genome-wide high-resolution aCGH analysis of gestational choriocarcinomas

Eleven samples of DNA from choriocarcinomas were studied by high resolution CGH-array 244 K. They were studied after histopathological confirmation of the diagnosis, of the androgenic etiology and after a microsatellite marker analysis confirming the absence of contamination of tumor DNA from maternal DNA. Three cell lines, BeWo, JAR, JEG were also studied by this high resolution pangenomic technique. According to aCGH analysis, the de novo choriocarcinomas exhibited simple chromosomal rearrangements or normal profiles. The cell lines showed various and complex chromosomal aberrations. 23 Minimal Critical Regions were defined that allowed us to list the genes that were potentially implicated. Among them, unusually high numbers of microRNA clusters and imprinted genes were observed.

Persistence and malignant sequelae of gestational trophoblastic disease: Clinical presentation, diagnosis, treatment and outcome

BACKGROUND

The major concern in gestational trophoblastic disease is management of persistent disease and malignant sequelae. However, prediction of response to treatment is difficult and methods used controversial.

AIM AND METHODS

To evaluate the usefulness of clinical presentation, methods of diagnosis and categorisation of risk in determining clinical outcomes, by analysis of a database of 705 registered patients collected over 30 years.

RESULTS

From the database, there were 97 patients who developed persistent disease and malignant sequelae on the basis of defined criteria - 80.4% had molar pregnancy and 19.6% non-molar pregnancy. Vaginal bleeding was not a common presentation; 59.8% had no clinical symptoms. According to protocol, monitoring by serial human chorion gonadotrophin (HCG) levels followed by imaging screen was used in all patients; histology was also available in 41.2% from hysterectomy and curettage specimens. There were 16 of 76 patients with persisting disease who had metastases (21.1%), and 2 of 20 patients with choriocarcinoma who had an antecedent molar pregnancy (10.0%). Based on five risk factors, 25 patients were categorised as 'high risk' and assigned to receive multi-drug chemotherapy. There were two deaths (2.1% for all malignant sequelae); both were from molar pregnancies. One patient failed to respond and the other suffered a complication of intensive chemotherapy.

CONCLUSION

Serial HCG levels remain the best monitor to determine therapeutic response. Categorisation of 'high risk' by five factors is useful in treatment. Albeit a small series, clinical outcome is favourable with a five-year survival of 89.7%.

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.

Epithelioid trophoblastic tumor: comparative genomic hybridization and diagnostic DNA genotyping

Arising from the putative chorionic-type intermediate trophoblast, epithelioid trophoblastic tumor is a recent addition to the spectrum of gestational trophoblastic diseases. Frequently, the tumor involves the uterine cervix and is misdiagnosed as invasive squamous-cell carcinoma. The pathogenesis of the tumor is poorly understood, and its molecular analysis is essentially lacking. This study was designed to explore chromosomal alterations in epithelioid trophoblastic tumor and to use DNA genotyping to demonstrate its trophoblastic origin, therefore separating the tumor from its mimics of the maternal origin. Five cases of epithelioid trophoblastic tumors were included in this study and paired DNA samples from the tumor and normal tissue were extracted from paraffin-embedded archival materials. The status of chromosomal alterations was analyzed by comparative genomic hybridization using conventional metaphase chromosome preparations. The parental genetic contribution was determined by DNA genotyping analysis using AmpFISTR Identifiler Amplification system (Applied Biosystems Inc.). Comparative genomic hybridization analysis was successful in three cases analyzed, all of which showed a balanced chromosomal profile without detectable gain or loss of the genome. DNA genotyping was informative in four epithelioid trophoblastic tumor involving anatomic locations including the cervix (two cases), endomyometrium (one case) and lung (metastatic, one case). All four cases were found to have unique paternal alleles, confirming the trophoblastic nature of the tumors. In summary, chromosomal alterations detectable by conventional comparative genomic hybridization are not features of epithelioid trophoblastic tumors. In difficult cases, the presence of the paternal alleles demonstrated by DNA genotyping is a powerful diagnostic application in separating an epithelioid trophoblastic tumor from its maternal mimics, particularly the far more common squamous-cell carcinoma of the uterine cervix.

A distinct pattern in the DNA ploidy histograms of hydatidiform moles and nonmolar abortuses is caused by accumulation of trophoblasts in the late s-phase

DNA ploidy analysis is a useful tool to distinguish the partial hydatidiform moles (PMs) from complete hydatidiform moles (CMs) and nonmolar abortuses (NAs). DNA ploidy histograms of hydatidiform moles are sometimes difficult to interpret because of the uneven distribution of nuclei in the S-phase, simulating aneuploid peaks. In this study, we analyzed DNA ploidy histograms of 25 CMs, 16 PMs, and 28 NAs, with special reference to the accumulation of cells in the late S-phase using a high-resolution DNA image cytometry. All the gestational products demonstrated the accumulation of cells in the late part of the S-phase fraction. To objectify the observation, we compared the percentage of cells in the second quarter with that of the third quarter of the S-phase fraction. All the gestational products had significantly lower (P < 0.001) percentage of cells in the second compared with that of the third quarter of the S-phase. The mean ratios of the third quarter to the second quarter in CMs, PMs, and NAs were 1.9, 1.7, and 2.5, respectively. This was significantly different from that of highly proliferative endometrial carcinomas. The knowledge of this specific S-phase fraction distribution in molar and nonmolar pregnancy material is important when interpreting the DNA histograms. The possibility of hypoxia being the cause of this phenomenon is also discussed.

Gestational trophoblastic neoplasia management: an update

PURPOSE OF REVIEW

Gestational trophoblastic neoplasia represents the malignant end of the gestational trophoblastic disease spectrum. This review updates readers on developments in the management of gestational trophoblastic neoplasia over the past few years.

RECENT FINDINGS

Progress has been made in elucidating the genetic changes that give rise to gestational trophoblastic neoplasia. The importance of accurate human chorionic gonadotrophin monitoring and the types of human chorionic gonadotrophin produced in cancer are also topical. Fortunately, most patients are cured with chemotherapy, and the choice of treatment schedule according to low-risk and high-risk prognostic groups is relatively unchanged. Indeed, most patients with low-risk gestational trophoblastic neoplasia are treated with single agent chemotherapy, and those who have high-risk disease with combination chemotherapy using etoposide, methotrexate and actinomycin D, alternating with cyclophosphamide and oncovine. For resistant disease, new paclitaxel-containing regimens appear better tolerated than etoposide and cisplatin alternating weekly with etoposide, methotrexate and actinomycin D.

SUMMARY

Prognosis in gestational trophoblastic neoplasia is now excellent following treatment. Virtually all patients with low-risk disease are cured, and survival is now 86% in high-risk patients. Optimization of treatment strategies for those who develop drug resistance remains a key challenge.

Identification of a novel tumor transforming gene GAEC1 at 7q22 which encodes a nuclear protein and is frequently amplified and overexpressed in esophageal squamous cell carcinoma

By comparative DNA fingerprinting, we identified a 357-bp DNA fragment frequently amplified in esophageal squamous cell carcinomas (ESCC). This fragment overlaps with an expressed sequence tag mapped to 7q22. Further 5' and 3'-rapid amplification of cDNA ends revealed that it is part of a novel, single-exon gene with full-length mRNA of 2052 bp and encodes a nuclear protein of 109 amino acids ( approximately 15 kDa). This gene, designated as gene amplified in esophageal cancer 1 (GAEC1), was located within a 1-2 Mb amplicon at 7q22.1 identified by high-resolution 1 Mb array-comparative genomic hybridization in 6/10 ESCC cell lines. GAEC1 was ubiquitously expressed in normal tissues including esophageal and gastrointestinal organs; with amplification and overexpression in 6/10 (60%) ESCC cell lines and 34/99 (34%) primary tumors. Overexpression of GAEC1 in 3T3 mouse fibroblasts caused foci formation and colony formation in soft agar, comparable to H-ras and injection of GAEC1-transfected 3T3 cells into athymic nude mice formed undifferentiated sarcoma in vivo, indicating that GAEC1 is a transforming oncogene. Although no significant correlation was observed between GAEC1 amplification and clinicopathological parameters and prognosis, our study demonstrated that overexpressed GAEC1 has tumorigenic potential and suggest that overexpressed GAEC1 may play an important role in ESCC pathogenesis.

Molecular targets in gynaecological cancers

The application of high throughput expression profiling and other advanced molecular biology laboratory techniques has revolutionised the management of cancers and is gaining attention in the field of gynaecological cancers. Such new approaches may help to improve our understanding of carcinogenesis and facilitate screening and early detection of gynaecological cancers and their precursors. Individualised prediction of patients' responses to therapy and design of personalised molecular targeted therapy is also possible. The studies of various molecular targets involved in the various signal pathways related to carcinogenesis are particularly relevant to such applications. At the moment, the application of detection and genotyping of human papillomavirus in management of cervical cancer is one of the most well established appliances of molecular targets in gynaecological cancers. Methylation, telomerase and clonality studies are also potentially useful, especially in assisting diagnosis of difficult clinical scenarios. This post-genomic era of clinical medicine will continue to make a significant impact in routine pathology practice. The contribution of pathologists is indispensable in analysis involving tissue microarray. On the other hand, both pathologists and bedside clinicians should be aware of the limitation of these molecular targets. Interpretation must be integrated with clinical and histopathological context to avoid misleading judgement. The importance of quality assurance of all such molecular techniques and their ethical implications cannot be over-emphasised.

Evaluation of deletions in 7q11.2 and 8p12–p21 as prognostic indicators of tumour development following molar pregnancy

OBJECTIVES

Previous studies have identified loss of chromosomal regions 7p12-q11.2 and 8p12-p21 in choriocarcinoma suggesting that suppressor genes involved in tumour development may be located within these regions. Our objectives were to refine the regions of loss and evaluate these deletions as prognostic indicators of trophoblastic tumour development following molar pregnancy.

METHODS

Fluorescent microsatellite genotyping was used to perform deletion mapping in a series of thirty-nine gestational trophoblastic tumours (GTT) including both choriocarcinoma and placental site trophoblastic tumours.

RESULTS

Significant loss of heterozygosity (LOH) was found for both regions in GTT that originated in non-molar pregnancies. Although no common interval of loss was found in those GTT with LOH for the 7q11.2 region, for the 8p12-p21 locus, markers D8S1731 and NEFL defined a minimal region of loss in all tumours showing LOH. However, complete LOH of either region occurred in only a minority of tumours (20%; chromosome 7: 24%; chromosome 8) suggesting that loss of neither region is likely to be a primary event in the development of GTT. This was further supported by the observation that no deletions were found in either region for the fourteen GTT that followed complete molar pregnancies.

CONCLUSIONS

While we have defined a minimal interval in 8p12-p21 in which tumour suppressor genes involved in GTT are likely to be located, the data suggest that deletions in 7q11.2 or 8p12-p21 are unlikely to be useful prognostic indicators in the management of patients with molar pregnancies.

Des andro- et parthénogénotes humains (môles hydatiformes et tératomes ovariens) au cancer

Genomic imprinting is a process that appeared in mammals. This phenomenon blocks the normal development of parthenogenic and androgenic conceptuses, that is to say benign ovarian teratomas and hydatidiform moles respectively. Pathological modifications of these conceptuses depend on whether the chromosomes come from the mother or father. These pathologies are associated with an accidental anomaly during gametogenesis and/or fertilizing. These reproductive anomalies are sporadic and some familial cases may exist suggesting a genetic control of such diseases. The human andro- and parthenogenetic conceptuses, but more frequently the moles, may be invasive (choriocarcinoma). An imbalance of the imprinting genes may initiate the deregulation of other genes, including oncogenes and anti-oncogenes, which can explain the cancerous modification. Immunological and environmental factors must be also considered (presence of the only paternal chromosomes in the choriocarcinoma). Numerous works on this subject are published and some recent important discoveries underline the roles of genes HOX, Tim P3, E-cad and p-16, and the recurrent chromosome anomalies 7q21+and 8p21- in the mole to choriocarcinoma processing. Although these phenomena are complex and heterogeneous, the andro- and parthenogenote conceptuses are particularly interesting models with which to understand developmental disorders and cancerous progression.

Gestational trophoblastic diseases: recent advances in histopathologic diagnosis and related genetic aspects

Gestational trophoblastic disease refers to a spectrum of proliferative disorders of the placental trophoblast, with a wide range of histologic appearances and clinical behaviors. This review discusses the more recent developments in the diagnosis of these entities. Changes in criteria for the histologic diagnosis of these lesions due to earlier clinical diagnosis are reviewed, and the ability to make more accurate diagnoses due to the introduction of newer antibodies such as p57 is highlighted. A discussion of epithelioid trophoblastic tumor, a newly introduced tumor subtype, with its differential diagnosis from placental-site trophoblastic tumor and squamous cell carcinoma is also presented. Last, a brief discussion on the role of genetic studies and the future direction of research in elucidating the nature of this intriguing group of lesions is presented.

Detection of chromosomal abnormalities by comparative genomic hybridization

PURPOSE OF REVIEW

Comparative genomic hybridization (CGH) is a modified in-situ hybridization technique. In this type of analysis, two differentially labeled genomic DNAs (study and reference) are cohybridized to normal metaphase spreads or to microarray. Chromosomal locations of copy number changes in the DNA segments of the study genome are revealed by a variable fluorescence intensity ratio along each target chromosome. Thus, CGH allows detection and mapping of DNA sequence copy differences between two genomes in a single experiment.

RECENT FINDINGS

Since its development, comparative genomic hybridization has been applied mostly as a research tool in the field of cancer cytogenetics to identify genetic changes in many previously unknown regions. It is also a powerful tool for detection and identification of unbalanced chromosomal abnormalities in prenatal, postnatal and preimplantation diagnostics.

SUMMARY

The development of comparative genomic hybridization and increase in resolution analysis by using the microarray-based technique offer new information on chromosomal pathologies and thus better management of patients.

Choriocarcinoma involving the pancreas as first manifestation of a metastatic regressing mixed testicular germ cell tumor

We describe an unusual case of metastatic choriocarcinoma of the pancreas arising from a regressing testicular mixed germ cell tumor that clinically mimicked a primary pancreatic tumor. A 54-year-old male presented with a 2-month history of progressive upper abdominal pain, weight loss, and jaundice. He also had a history of recurrent epididymitis associated with the presence of a right testicular mass shown to be cystic by ultrasound and stable for at least 10 years. A computed tomography scan showed an isolated 6 cm mass in the head of the pancreas. A pancreaticoduodenectomy was performed. Upon histological examination, the pancreatic tumor showed extensive hemorrhage and necrosis. In the viable area, the tumor was composed of an intimate mixture of mononuclear cytotrophoblast cells and multinucleated syncytiotrophoblasts with vascular invasion. These characteristic features led to the correct diagnosis on frozen section. The cytology of the tumor was nonspecific and suggested undifferentiated carcinoma of the pancreas. The trophoblastic origin of the tumor cells was confirmed by immunohistochemistry staining. The testicular mass showed a regressed mixed germ cell tumor of predominantly seminoma with focal teratoma but without a choriocarcinoma component. In conclusion, we present a rare and unusual case of a regressing testicular mixed germ cell tumor that presented as a primary pancreatic tumor. Cytological features of the pancreatic mass were not specific and raised the possibility of a primary undifferentiated carcinoma of the pancreas. Characteristic histological features of choriocarcinoma led to the correct diagnosis on frozen section. Subsequent resection of the testicular mass confirmed the presence of a cystic and scarring (regressing) mixed germ cell tumor but without evidence of choriocarcinoma.

Comparative genomic hybridization study of placental site trophoblastic tumour: a report of four cases

Placental site trophoblastic tumour (PSTT) is a neoplastic proliferation of the implantation intermediate trophoblast. Although clinicopathological studies are not uncommon in case reports or small series, molecular and genetic studies are quite limited. Four archived cases of PSTT were successfully analysed by comparative genomic hybridization (CGH) in this study. Regional chromosomal gains were observed in two cases. One case showed chromosomal gains in the regions of 19p13.2, 21q11-21 and 22q12. The second case demonstrated a single regional chromosomal gain involving 21q21. No chromosomal loss is observed. The remaining two cases showed a balanced CGH profile without detectable chromosomal gain or loss. In summary, although chromosomal alterations detectable by CGH are not common, rare chromosomal gains do occur in PSTT. The recurrent chromosomal gain involving chromosomal 21q observed in two of our cases deserves additional studies to ascertain whether it carries any pathobiological significance.

Temporal regulation of the expression of syncytin (HERV-W), maternally imprinted PEG10, and SGCE in human placenta

Maternally imprinted PEG10 and SGCE, separated by approximately 2.15 Mb from Syncytin (HERV-W) gene at 7q21.3, are implicated in choriocarcinoma and Silver-Russell syndrome. Here we have analyzed the temporal regulation of mRNA expression of these genes in placenta and demonstrate that Syncytin gene activation is highest in term placenta, PEG10, downregulated at early hypoxic phase, and highly activated at 11-12 wk of gestation. In contrast, transcription from SGCE remained unchanged throughout pregnancy, suggesting two neighboring imprinted genes are differentially regulated at very early pregnancy. Additionally, accumulation of two major species of mRNA (8 kb and 3.1 kb) encoded by HERV-W in placenta is regulated: 3.1 kb mRNA level remained unchanged throughout pregnancy, whereas the production of 8 kb species was highest in term placenta. Western blot and immunohistochemical staining of placental tissues with monoclonal antibodies revealed a marked reduction of syncytin glycoprotein synthesis in late pregnancy. Therefore, the relative levels of 3.1 kb and 8 kb mRNAs in trophoblasts could regulate syncytin protein synthesis, possibly by competition of the two mRNA species for translational apparatus.

A new imprinted cluster on the human chromosome 7q21-q31, identified by human-mouse monochromosomal hybrids

We have previously established a series of human monochromosomal hybrids containing a single human chromosome of defined parental origin as an in vitro resource for the investigation of human imprinted loci. Using the hybrids with a paternal or maternal human chromosome 7, we determined the allelic expression profiles of 76 ESTs mapped to the human chromosome 7q21-q31. Seven genes/transcripts, including PEG10 which has previously been reported to be imprinted, showed parent-of-origin-specific expression in monochromosomal hybrids. One of the 6 candidate genes/transcripts, i.e., DLX5 was confirmed to be imprinted in normal human lymphoblasts and brain tissues by a polymorphic analysis. Thus, an imprinted domain has been newly defined in the region of human chromosome 7q21-q31 using human-mouse monochromosomal hybrids.

Compilation of published comparative genomic hybridization studies

The power of comparative genomic hybridization (CGH) has been clearly proven since the first paper appeared in 1992 as a tool to characterize chromosomal imbalances in neoplasias. This review summarizes the chromosomal imbalances detected by CGH in solid tumors and in hemopathies. In May of 2001, we took a census of 430 articles providing information on 11,984 cases of human solid tumors or hematologic malignancies. Comparative generic hybridization has detected a number of recurrent regions of amplification or deletion that allows for identification of new chromosomal loci (oncogenes, tumor suppressor genes, or other genes) involved in the development, progression, and clonal evolution of tumors. When CGH data from different studies are combined, a pattern of nonrandom genetic aberrations appears. As expected, some of these gains and losses are common to different types of pathologies, while others are more tumor-specific.

Malignant placental site trophoblastic tumor: a cytogenetic study using comparative genomic hybridization and chromosome in situ hybridization

BACKGROUND

Placental site trophoblastic tumor (PSTT) is a rare form of gestational trophoblastic neoplasm composed predominantly of intermediate trophoblast. Most showed benign behavior whereas 10-15% of PSTTs were clinically malignant with later recurrence and metastasis. Currently, there are no reliable means to predict clinical outcome, and cytogenetic information is scanty.

METHODS

The clinicopathologic features of two cases of malignant PSTT were analyzed. Cytogenetic analysis was performed by comparative genomic hybridization (CGH) and chromosome in situ hybridization (CISH) using frozen tissue and paraffin embedded sections, respectively.

RESULTS

Both patients were 32 years old at time of diagnosis. One patient with PSTT presented with menorrhagia, and the other presented with symptoms of missed abortion. Elevated serum human chorionic gonadotropin (HCG) was detected in both patients. Histologic examination showed the typical features of PSTT with high mitotic count (> 5/10 high-power fields). Ovarian and lung metastasis occurred in both patients. Immunohistochemical staining revealed an equal distribution of HCG and human placental lactogen. Cytogenetic studies by CISH showed that karyotypes of these two malignant PSTTs were diploid. Analysis of the tumor tissue by CGH did not show any changes in DNA copy numbers.

CONCLUSIONS

The authors' study indicated that the two metastasizing PSTTs had balanced diploid karyotype. The malignant behavior of PSTTs may be not related to the DNA copy number changes. Such cytogenetic study may be useful in distinguishing metastatic PSTT from choriocarcinoma.

Current understandings of the molecular genetics of gestational trophoblastic diseases

Gestational trophoblastic disease (GTD) is a heterogeneous group of diseases characterized by abnormally proliferating trophoblastic tissues. This includes partial and complete hydatidiform moles, invasive mole, choriocarcinoma and placental site trophoblastic tumour. Cytogenetic studies revealed that hydatidiform moles contain either solely (as in complete moles) or an excess (as in partial moles) of paternal contribution to the genome. Genomic imprinting is believed to play a pivotal role in the pathogenesis of hydatidiform moles. However its precise role and mechanism remains poorly understood. Hydatidiform mole carries a potential of malignant transformation. Similar to other human cancers, malignant transformation in gestational trophoblastic tumours is likely a multistep process and involves multiple genetic alterations including activation of oncogenes and inactivation of tumour suppressor genes. In addition, expression of telomerase activity, altered expression of cell--cell adhesion molecules and abnormal expression of matrix metalloproteinases have also been reported in GTD. These represent disruption of the delicate balance and regulation of cellular processes including proliferation, differentiation, apoptosis and invasion. The significance of these alterations in the pathogenesis and malignant transformation of gestational trophoblastic diseases is reviewed in this paper.

Gastric choriocarcinoma shows characteristics of adenocarcinoma and gestational choriocarcinoma: a comparative genomic hybridization and fluorescence in situ hybridization study

The authors report two cases of the rare primary gastric choriocarcinoma. These tumors showed an overwhelming predominance of cytotrophoblast- and syncytiotrophoblast-like tumor cells that were positive for beta-human chorionic gonadotrophin, with small foci of glandular differentiation. Beta-human chorionic gonadotrophin was also detected serologically in one patient. Comparative genomic hybridization study was performed on one specimen. Copy number gains of chromosomes 12, 17, 20, 22, and X, together with losses on 18q, were the major findings. Except for the gain of chromosome 12, which is known to be uncommon in primary gastric adenocarcinoma but frequently associated with choriocarcinoma, the remaining genomic imbalances were among the most common comparative genomic hybridization findings reported in primary gastric adenocarcinoma. Fluorescence in situ hybridization on paraffin sections of both specimens confirmed the presence of polysomy 17 and trisomy 12. These results suggest that primary gastric choriocarcinoma genetically possesses characteristics of both adenocarcinoma and gestational choriocarcinoma. The authors believe this is the first interphase cytogenetics study on this rare tumor, and that the results support the theory that gastric choriocarcinoma arises from alternate differentiation pathways of adenocarcinoma.

A retrotransposon-derived gene, PEG10, is a novel imprinted gene located on human chromosome 7q21

A novel paternally expressed imprinted gene, PEG10 (Paternally Expressed 10), was identified on human chromosome 7q21. PEG10 is located near the SGCE (Sarcoglycan epsilon) gene, whose mouse homologue was recently shown to be imprinted. Therefore, it is highly possible that a new imprinted gene cluster exists on human chromosome 7q21. Analysis of two predicted open reading frames (ORF1 and ORF2) revealed that ORF1 and ORF2 have homology to the gag and pol proteins of some vertebrate retrotransposons, respectively. These data suggest that PEG10 is derived from a retrotransposon that was previously integrated into the mammalian genome. PEG10 is likely to be essential for understanding how exogenous genes become imprinted.

Comparative genomic hybridization detects losses of chromosomes 22 and 16 as the most common recurrent genetic alterations in primary ependymomas

In this study, we used comparative genomic hybridization to provide an overview of chromosomal imbalances in a series of 20 adult and 8 childhood ependymomas. All tumors displayed multiple genomic imbalances. Loss of genetic material was observed in chromosomes 22q (71%), 16 (57%), 17 (46%), 6 (39%), 19q (32%), 20q (32%), and 1p (29%), with the overlapped deletion regions determined at 16p13.1-13.3, 16q22-q24, 19q13.1-13.4, 20q13.1-13.2 and 1p36.1-36.3. Gain of DNA was commonly detected on chromosomes 5q (46%), 12q (39%), 7q (36%), 9q (36%), and 4q (32%), with overlapped regions of gain mapped to 5q21-22, 12q15-24.1, 7q11.2-31.2, 9q12-32, and 4q23-28, respectively. These findings suggest a greater degree of genomic imbalance in ependymomas than has been recognized previously and highlight chromosomal loci likely to contain oncogenes or tumor suppressor genes that may contribute to the molecular pathogenesis of this tumor. Our study also confirmed previous findings on frequent losses of 17 and 22q in ependymomas and further identified chromosome 16 loss as a common recurrent genetic aberration in ependymomas.

Gestational trophoblastic diseases: new standards for therapy

Gestational trophoblastic disease (GTD) is a spectrum of rare neoplastic conditions that are highly curable, even in the presence of widely metastatic disease. These diseases vary from partial hydatidiform mole, which rarely metastasizes and infrequently requires treatment with chemotherapy, to choriocarcinoma, for which multi-agent chemotherapy is the standard treatment. Much has been learned regarding the epidemiology of this disease, and our understanding of the genetics underlying GTD is rapidly expanding. As technology such as ultrasonography and sensitive tests for beta-human chorionic gonadotropin have evolved, the presentation of molar pregnancy has significantly changed, although the incidence of persistent GTD has not decreased. This review highlights these recent advancements in the epidemiology, genetics, diagnosis, and treatment of gestational trophoblastic disease.

Cytogenetic analysis from DNA by comparative genomic hybridization

Comparative genomic hybridization (CGH) is a modified in situ hybridization technique which allows detection and mapping of DNA sequence copy differences between two genomes in a single experiment. In CGH analysis, two differentially labelled genomic DNA (study and reference) are co-hybridized to normal metaphase spreads. Chromosomal locations of copy number changes in the DNA segments of the study genome are revealed by a variable fluorescence intensity ratio along each target chromosome. Since its development, CGH has been applied mostly as a research tool in the field of cancer cytogenetics to identify genetic changes in many previously unknown regions. CGH may also have a role in clinical cytogenetics for detection and identification of unbalanced chromosomal abnormalities.