Complex karyotypic alterations in an endometrial stromal sarcoma

Fusion of the genes BRD8 and PHF1 in endometrial stromal sarcoma

We present a new endometrial stromal sarcoma (ESS)‐associated genomic rearrangement involving chromosome arms 5p and 6p and leading to the formation of a BRD8‐PHF1 fusion gene. The PHF1 (PHD finger protein 1) gene, from 6p21, is known to be rearranged in ESS in a promiscuous way inasmuch as it has been shown to recombine with JAZF1, EPC1, MEAF6, and now also with BRD8, in tumors of this type. In all rearrangements of PHF1, including the present one, a recurrent theme is that the entire coding part of PHF1 constitutes the 3′ end of the fusion. BRD8 (bromodomain containing 8) encodes a protein which is involved in regulation of protein acetylation and/or histone acetyl transferase activity. All the genetic fusions identified so far in ESS appear to recombine genes involved in transcriptional regulation, that is, polycomb group complex‐mediated and aberrant methylation/acetylation genes. This adds to the likelihood that the new BRD8‐PHF1 shares the same pathogenetic mechanism as the other ESS‐specific rearrangements.

Molecular characteristics of uterine sarcomas

INTRODUCTION

Uterine sarcomas are rare cancers, of which the most common entities are leiomyosarcoma and endometrial stromal sarcoma. These two tumors may have overlapping clinical presentation, morphology and immunohistochemical profile, but are increasingly recognized to be two molecularly distinct entities. Endometrial stromal sarcomas are further currently divided into a low-grade and high-grade group based on molecular characteristics. Area covered: This review discusses recent data which shed light on the molecular profile of these two cancers and may aid in understanding their evolution and progression, in the aim of improving their diagnosis and management. Search was through PubMed, with focus on studies published in the last 5 years. Expert commentary: The literature presented and discussed documents rapidly expanding knowledge of the genetic characteristics of leiomyosarcoma and endometrial stromal sarcoma, with an array of molecules and pathways implicated in the biology of these cancers. Several of these molecules are potential therapeutic targets. Assessment of their predictive and prognostic role awaits larger studies.

Genomic characterization of endometrial stromal sarcomas with array comparative genomic hybridization

INTRODUCTION

The endometrial stromal sarcoma (ESS) is a very rare uterine sarcoma, counting for 1-3% of all gynecologic malignancies. ESS represents 0.2-8% of all uterine malignant tumors and accounts for about 10% of all uterine sarcomas. With regard to chromosomal aberrations, very little is known about benign and malignant endometrial stromal tumors.

METHODS

30 tumors, consisting of 4 cases of benign endometrial stromal nodule (ESN), 22 cases of low-grade ESS and 4 cases of undifferentiated endometrial sarcoma (UES), were analyzed by array-comparative genomic hybridization (aCGH).

RESULTS

ESN did not show many copy number changes (CNCs) by aCGH. Frequent losses could be identified on chromosomes 7p and 19, and gains on chromosomes 1q, 6p and 8q. Low-grade ESS presented as a very heterogeneous group. 90% (20/22) of cases displayed aberrations. Most frequent changes were losses on chromosomes 7 and 22, and gains on chromosome 1q or 11. UES showed a high number of chromosomal aberrations and on every chromosome CNCs were detected. Most frequent changes were losses on chromosomes 1q, 2q (3/4, 75%) and 13, and gains on chromosomes 1q and 17p.

CONCLUSION

Our data shows an increasing number of CNCs from ESN to low-grade ESS and to UES. However, the chromosomal aberrations differ considerably between the investigated ESN-, low-grade ESS- and UES cases and thus, a linear tumor progression seems to be unlikely.

JAZF1 rearrangement in a mesenchymal tumor of nonendometrial stromal origin: report of an unusual ossifying sarcoma of the heart demonstrating JAZF1/PHF1 fusion

Rearrangements of JAZF1 are a frequent genetic aberration in endometrial stromal tumors. We report a distinct primary cardiac ossifying sarcoma that harbored a JAZF1/PHF1 fusion. The patient was a 70-year-old man with a history of a 6.8 cm calcific intramural left ventricular mass. Six years after his initial evaluation, the patient developed multiple lung metastases and ultimately died of disease-related complications. Histologically, the cardiac tumor and lung metastases demonstrated an infiltrative, malignant spindle cell neoplasm that grew in short fascicles with areas of bone formation, nuclear palisading, and necrosis. The neoplastic cells were relatively monomorphic in a background of an amorphous collagenous matrix. Immunohistochemical analysis was positive for vimentin and negative for wide-spectrum cytokeratins, S100 protein, desmin, smooth muscle actin, and CD34. Fluorescence in situ hybridization using a dual-color, single-fusion probe set identified the JAZF1/PHF1 fusion. The unique morphology and the presence of a JAZF1/PHF1 rearrangement suggest that this distinctive ossifying sarcoma is not part of a currently established diagnostic entity, representing instead a novel primary cardiac sarcoma. This case also represents the first description of a JAZF1 fusion in a tumor outside the spectrum of endometrial stromal neoplasms.

Uterine tumors resembling ovarian sex cord tumors (UTROSCT) lack the JAZF1-JJAZ1 translocation frequently seen in endometrial stromal tumors

Uterine tumor resembling ovarian sex cord tumor (UTROSCT) is a rare uterine neoplasm composed predominantly or exclusively of cells which resemble those seen in sex cord tumors of the ovary. Since its initial morphologic description, it has been unclear whether UTROSCT represents a variant within the spectrum of endometrial stromal tumors (ESTs), which may rarely exhibit areas of sex cord-like differentiation, or whether it is a distinct uterine neoplasm unrelated to ESTs. Recently, several studies have revealed a recurrent t(7;17) translocation resulting in a JAZF1-JJAZ1 gene fusion in over 60% of EST and its variants, including 2 out of 4 endometrial stromal tumors with sex cord-like elements (ESTSCLE). We examined UTROSCTs for evidence of the JAZF1-JJAZ1 gene fusion by fluorescence in situ hybridization and by reverse transcriptase polymerase chain reaction in 24 and 20 cases, respectively. The JAZF1-JJAZ1 gene fusion was not identified in any tumor by either method. Although we cannot entirely exclude that UTROSCT represents a variant of ESTSCLE which lacks this translocation, our findings suggest that UTROSCT does not share the genetic mechanism common to the majority of ESTs with or without sex cord-like differentiation, and therefore most likely represents a distinct neoplasm unrelated to ESTSCLE.

An endometrial stromal sarcoma cell line with the JAZF1/PHF1 chimera

Endometrial stromal sarcomas (ESS) are rare malignancies, accounting for less than 10% of uterine sarcomas. Apart from the chromosomal rearrangement t(7;17)(p15;q21), which leads to the JAZF1/SUZ12 chimera, cytogenetic studies have shown that the chromosome band 6p21 is often rearranged in ESS. The translocation partners involved in the 6p21 rearrangements differ among the tumors, but chromosome 7 is involved in most aberrations. A JAZF1/PHF1 fusion gene was recently found in two tumors showing an exchange between 6p and 7p rearrangement. In the present study, we show that a low-grade ESS cell line carrying a der(7)t(6;7)(p21;p22) also harbors the a JAZF1/PHF1 fusion. In the fusion transcript, exon 3 of JAZF1 was fused with exon 2 of PHF1. At the junction, there was an insertion of 26 nucleotides, originating from intron 3 of JAZF1, thus maintaining an open reading frame of the chimeric transcript. The predicted 684-amino acid JAZF1/PHF1 chimeric protein retained one zinc finger domain from JAZF1 and the two zinc finger domains from PHF1, and its oncogenic mechanism should be similar to that of the JAZF1/SUZ12 protein. The present cell line constitutes an excellent model for further studies on the impact of the JAZF1/PHF1 fusion.

High Frequency of JAZF1-JJAZ1 Gene Fusion in Endometrial Stromal Tumors With Smooth Muscle Differentiation by Interphase FISH Detection

The most common cytogenetic alteration observed in low-grade endometrial stromal tumors (EST) is the t(7;17)(p15;q21) translocation, resulting in the fusion of the JAZF1 and JJAZ1 genes. By reverse-transcription polymerase chain reaction, the translocation has been detected overall in one-third of ESTs, but only rarely in its variants. The purpose of this study was to develop a fluorescence in situ hybridization assay for detection of this translocation using archival paraffin-embedded samples of ESTs with smooth muscle differentiation and to assess the nature of the smooth muscle component of these tumors. Representative paraffin blocks of 9 endometrial stromal nodules and 1 low-grade endometrial stromal sarcoma were collected for the study. In 1 case, the block selected also contained areas of sex cordlike differentiation. A fluorescence in situ hybridization probe set was designed to detect the t(7;17)(p15;q12) on tissue sections. Six out of 10 collected ESTs were assessable. Fusion signals were detected in 3 out of 6 cases (50%) in both the conventional endometrial stromal and the smooth muscle components of the tumors. The tumor sample with sex cordlike differentiation harbored the fusion signal in all the 3 components. Our results support the contention that the endometrial stromal and smooth muscle components of these tumors have the same origin, either from a common precursor cell with pluripotential differentiation or from endometrial stromal cells that have undergone smooth muscle metaplasia. Our results indicate that the detection of this chromosomal abnormality can be used to diagnose ESTs with smooth muscle differentiation when the smooth muscle component is predominant.

Uterine sarcomas

A wide variety of sarcomas occur in the uterus but two subtypes - leiomyosarcoma and endometrial stromal sarcoma - account for a majority of those more routinely encountered. Using the 2003 World Health Organization classification, this review focuses on six uterine sarcomas: endometrial stromal sarcoma, undifferentiated endometrial sarcoma, leiomyosarcoma, rhabomyosarcoma, angiosarcoma and liposarcoma. The epidemiological, clinical, pathological and molecular features are presented along with therapeutic approaches. Familiarity with molecular aspects of these tumors and application of novel technologies in their assessment should be encouraged as they may provide alternate therapies resulting in improved survival for the patient. Clinical information necessary for accurate diagnosis of these lesions is emphasised. A multidisciplinary approach to management of patients with uterine sarcomas is essential for optimal management.

Chromosomal alterations in low-grade endometrial stromal sarcoma and undifferentiated endometrial sarcoma as detected by comparative genomic hybridization

OBJECTIVE

Endometrial stromal sarcomas (ESS) are very rare neoplasms constituting less than 0.5% of all malignant uterine tumors. The aim of the present study was to characterize the karyotypic abnormalities in these malignant mesenchymal tumors and to find specific chromosomal aberrations with eventual correlation with histologic grades.

METHODS

Twelve cases of endometrial stromal sarcomas consisting of nine low-grade ESS and three undifferentiated endometrial sarcomas (UES) were investigated by comparative genomic hybridization (CGH).

RESULTS

Ten of the twelve cases (83.3%) displayed chromosomal gains or losses. Deletions occurred more frequently than gains (63.4% versus 36.6%). In low-grade ESS, gains on 1, 6q, 9q, 16p, 19, 20q, 22q and losses on 2, 4q, 6, 7, 11q, 13q, 15q, 16q, 20p, X were detected. CGH with UES exhibited gains on 2q, 4q, 6q, 7p, 9q, 20q and losses on 3q, 10p, 14q. One low-grade ESS and one UES did not reveal any chromosomal aberration.

CONCLUSIONS

Chromosomal aberrations in endometrial sarcomas are heterogeneous and do not clearly correlate with the histologic grades. There is no increased accumulation of aberrations from low-grade ESS to UES. Despite the karyotypic variations, chromosomal deletion on 7p was the most common finding (55.6%) in low-grade ESS and may play a role in tumor development and progression.

Identification of a BAC clone overlapping the t(6p12.3) breakpoint in the cell line ESS-1 derived from an endometrial stromal sarcoma

A major subgroup of endometrial stromal sarcomas (ESS) is characterized by translocations involving chromosome 6 with consistent breakpoints at 6p11 approximately p21. As part of an ongoing positional cloning effort to identify the genes affected by these translocations, this article reports on the delineation of the 6p breakpoint in the cell line ESS-1 derived from an ESS. The G- and 4',6-diamidino-2-phenylindole-banded karyotypes showed an unbalanced translocation described originally as der(3)t(3;6) (q29;p21.1). Fluorescence in situ hybridization using probes derived from contigous yeast artificial chromosome, bacterial artificial chromosome (BAC), and P1-derived artificial chromosome clones specific to 6p12.3 approximately p21.1 located the breakpoint at 6p to the BAC clone RP11-337K13 mapping to 6p12.3. The DNA sequence of the breakpoint region contained in RP11-337K13 will serve as a candidate locus for further molecular genetic analyses to isolate the gene(s) altered in ESS with 6p rearrangement.

Endometrial stromal sarcoma with a sole t(X;17) chromosome change: report of a case and review of the literature

BACKGROUND

Endometrial stromal sarcomas (ESSs) exhibit varying degrees of malignancy and heterogeneity at the karyotypic level. The biological mechanisms that contribute to tumorigenesis of ESS are still largely unknown.

CASE

A 33-year-old woman suffering from ESS was treated primarily surgically. Cytogenetic evaluation of the primary uterine nodule and metastatic tumor showed 46,XX,t(X;17)(p11:q23) karyotype in all metaphases analyzed. Normal endometrial cells exhibited 46,XX karyotype. Fluorescence in situ hybridization analysis confirmed the presence of the reciprocal t(X;17) translocation and allowed for the positioning of the chromosome X breakpoint distal to SSX1 gene loci.

CONCLUSIONS

Our report of a previously undescribed sole cytogenetic translocation in an advanced stage of ESS might identify a cytogenetically distinct subgroup of ESS and help to reveal genes involved in ESS tumorigenesis.

Endometrial stromal sarcoma with clonal complex chromosome abnormalities. Report of a case and review of the literature

Only eleven endometrial stromal sarcomas (ESS) with clonal chromosomal abnormalities have been reported in the literature. Of these, four have been reported to harbor the t(7;17) translocation. We report here an additional ESS that exhibited clonal complex chromosome abnormalities not described earlier: 38,XX,-1,del(1)(q11),-2,add(2)(p13),-3,der(4)add(4)(p12)psu dic(4;14)(q35;q11.2), add(6)(p21.3),add(7)(q22),del(7)(p11.2p13),-8,-9,add(9)(q34),- 10,add(10)(q24),-11,-11,ins(12;?) (q13;?),-14,-14,-15,ins(15;?)(q22;?),add(16)(q22),add(17)(q11.2),- 18,der(18)t(7;18)(q11.2;p11.2),-19, add(20)(p13),add(21)(p11.2),-22,add(22)(p11.2),+6mar in metaphase cells from primary short-term culture.

Cytogenetics of uterine sarcomas: presentation of eight new cases and review of the literature

Tissue from 14 uterine tumor samples from eight patients-four with endometrial stromal sarcoma (ESS), two with leiomyosarcoma (ULMS), and two with malignant mixed mesodermal tumor (MMMT)-were investigated cytogenetically after short-term culturing. Clonal chromosome aberrations were found in 12 tumors. One ESS showed a recombination between 7p14 and 17q12, a rearrangement characterizing a subset of ESSs. In our series, chromosomes 1, 6, 7, and 16 were involved in structural aberrations most frequently (four cases each). Net loss of 6q material was found in four cases and bands 11q13, 16q13, and 22q13 were each rearranged in four cases. Among 43 uterine sarcomas, including 12 MMTs, now available for evaluation, some differences in breakpoint distribution among different tumor types were found. Rearrangements of bands 1p32, 3p24, and 10q22 were found exclusively in ULMS, whereas aberrations of bands 6p21, 7p21, and 17q12 were found predominantly in ESS.

Characterization of a newly established endometrial stromal sarcoma cell line

We describe a newly established human sarcoma cell line derived from an endometrial stromal sarcoma (ESS). The cell line has been maintained in long-term cell culture for more than 2 years. It has been repeatedly analyzed in terms of morphology, immunocytochemical features, ultrastructure and karyotypic characteristics. In contrast to uniform endometrial stromal differentiation in vivo, the tumor cells were shown to display distinct phenotypical heterogeneity in vitro. In addition to the predominant cell type, which retained sarcomatous differentiation, foci of epithelial-like cells were observed in the cell culture. Immunocytochemical and ultrastructural analysis demonstrated a mainly mesenchymal phenotype with signs of epithelial characteristics, such as expression of cytokeratins, and the presence of desmosomes and kinetocilia, respectively. Cytogenetic analyses in early and late passages revealed unbalanced translocations between chromosomes 3 and 6 and an additional i(19)(q10), as common karyotypic changes in all tumor cells, indicating a monoclonal origin. Our new cell line can be used as an in vitro model to study the mechanisms of heterogeneous differentiation patterns in ESS.

Cytogenetics and the surgeon: an invaluable tool in diagnosis, prognosis and counselling of patients with solid tumours

BACKGROUND

Cytogenetic studies have become an important part of tumour characterization. In a minority of tumours cytogenetic and/or molecular studies may be of help for diagnosis, selection of treatment protocols and predicting outcome.

METHODS

This article reviews the literature on solid tumour translocations and established family cancer syndromes. In addition, the potential importance of genetics in management of patients with breast, ovarian and pancreatic carcinoma is reviewed.

RESULTS AND CONCLUSION

Cytogenetic analysis of tumours may help confirm the diagnosis when conventional histology demonstrates no evidence of differentiation along a particular tissue pathway. For patients with well defined cancer syndromes, cytogenetic and molecular analysis offers the prospect of screening to reduce the risk of malignant disease. For many malignancies the underlying genetic anomalies are gradually being elucidated. Further studies designed to demonstrate the significance of these findings can only be undertaken if tumour material is collected and stored in optimal conditions for cytogenetic and/or molecular biological studies.

A third case of a low-grade endometrial stromal sarcoma with a t(7;17)(p14 approximately 21;q11.2 approximately 21)

Cytogenetic analysis of a low-grade endometrial stromal sarcoma of the uterus in a 52-year-old woman revealed the karyotype 46,XX,t(7;17)(p14 approximately 21;q11.2 approximately 21),der(7)t(7;16)(p14-15;q22)t(7;9) (q22;q22), der(9)t(7;9)(q22;q22),del(16)(q22). The t(7;17) was identical to an aberration observed in two other cases of endometrial stromal sarcomas, thus confirming the idea that it constitutes a non-random aberration for this type of tumor.