Cytogenetic findings in liposarcoma correlate with histopathologic subtypes

Patterns of Metastatic Recurrence of Genetically Confirmed Myxoid Liposarcoma

BACKGROUND

Most sarcomas metastasize predominantly to the lungs, and chest x-ray, or computed tomography, is the most commonly used staging investigation. Myxoid liposarcomas (MLSs) are rare tumors with a tendency to metastasize to extrapulmonary loci. The aim of this study was to assess the locations of the first metastases in MLS patients, to guide the design of effective staging and follow-up imaging protocols.

METHODS

Patients treated for MLS between 1987 and 2017 were identified in a prospectively maintained register. Histology of the tumors was reassessed. In addition, the presence of one of the pathognomonic gene translocations was confirmed, uniquely for a retrospective series. The surgical and oncological outcomes were reviewed. A comprehensive review of the literature was performed on the metastatic pattern of MLS, including series with 10 or more MLS patients with metastatic disease.

RESULTS

A total of 32 patients with genetically confirmed MLS were identified, with a median follow-up of 7.6 years. Seven patients (22%) developed metastatic disease, five initially intra-abdominally and only one to the lungs. The comprehensive review included 14 series with 1853 patients, 348 (19%) of whom had metastases. The location of the first metastases was soft tissues in 32% of patients, intra-abdominal in 26%, pulmonary in 24%, and bone in 17%.

CONCLUSIONS

MLSs metastasize often intra-abdominally and to extra-abdominal soft tissues. Thus, whole-body imaging may be indicated during the initial assessment and follow-up of these patients.

The Role of CDK Pathway Dysregulation and Its Therapeutic Potential in Soft Tissue Sarcoma

Soft tissue sarcomas (STSs) are tumors that are challenging to treat due to their pathologic and molecular heterogeneity and their tumor biology that is not yet fully understood. Recent research indicates that dysregulation of cyclin-dependent kinase (CDK) signaling pathways can be a strong driver of sarcogenesis. CDKs are enzyme forms that play a crucial role in cell-cycle control and transcription. They belong to the protein kinases group and to the serine/threonine kinases subgroup. Recently identified CDK/cyclin complexes and established CDK/cyclin complexes that regulate the cell cycle are involved in the regulation of gene expression through phosphorylation of critical components of transcription and pre-mRNA processing mechanisms. The current and continually growing body of data shows that CDKs play a decisive role in tumor development and are involved in the proliferation and growth of sarcoma cells. Since the abnormal expression or activation of large numbers of CDKs is considered to be characteristic of cancer development and progression, dysregulation of the CDK signaling pathways occurs in many subtypes of STSs. This review discusses how reversal and regulation can be achieved with new therapeutics and summarizes the current evidence from studies regarding CDK modulation for STS treatment.

Cytogenomic Characterization of Giant Ring or Rod Marker Chromosome in Four Cases of Well-Differentiated and Dedifferentiated Liposarcoma

Chromosome and array comparative genomic hybridization (aCGH) analyses were performed on two cases of well-differentiated liposarcoma (WDLPS) and two cases of dedifferentiated liposarcoma (DDLPS). The results revealed the characteristic giant ring (GR) or giant rod marker (GRM) chromosomes in all four cases and amplification of numerous somatic copy number alterations (SCNAs) involving a core segment of 12q14.1q15 and other chromosomal regions in three cases. The levels of amplification for oncogenes OS9, CDK4, HMGA2, NUP107, MDM2, YEATS4, and FRS2 at the core segment or other SCNAs should be characterized to facilitate pathologic correlation and prognostic prediction. Further studies for the initial cellular crisis event affecting chromosome intermingling regions for cell-type specific gene regulation may reveal the underlying mutagenesis mechanism for GR and GRM in WDLPS and DDLPS.

Can radiomics improve the prediction of metastatic relapse of myxoid/round cell liposarcomas?

OBJECTIVE

The strongest adverse prognostic factor in myxoid/round cell liposarcomas (MRC-LPS) is the presence of a round cell component above 5% within the tumor bulk. Its identification is underestimated on biopsies and in the neoadjuvant setting. The aim was to improve the prediction of patients' prognosis through a radiomics approach.

METHODS

Thirty-five out of 89 patients with MRC-LPS managed at our sarcoma reference center from 2008 to 2017 were included in this IRB-approved retrospective study as they presented with a pre-treatment contrast-enhanced MRI (median age, 49 years old). Two radiologists reported usual conventional/semantic radiological variables. After signal intensity (SI) normalization, voxel size standardization of T2-WI, and whole tumor volume segmentation, 44 3D-radiomics features were extracted. Using least absolute shrinkage and selection operator penalized Cox regression on prefiltered features, a radiomics score based on 3 weighted radiomics features was generated. Four prognostic multivariate models for MRFS were compared using concordance index: (1) clinical model, (2) semantic radiological model, (3) radiomics model, and (4) radiomics + semantic radiological model.

RESULTS

Twelve patients showed a metastatic relapse. The radiomics score included FOS_Skewness, GLRLM_LRHGE, and SHAPE_Volume and correlated with MRFS (hazard ratio = 19.37, p = 0.0009) and visual heterogeneity on T2-WI (p < 0.0001). A high score indicated a poorer prognosis. After adjustment, the best predictive performances were obtained with model (4) (concordance index = 0.937) and the lowest with model (1) (concordance index = 0.637).

CONCLUSION

Adding selected radiomics features that quantify tumor heterogeneity and shape at baseline to a conventional radiological analysis improves prediction of MRC-LPS patients' prognosis.

KEY POINTS

• Fourteen radiomics features quantifying shape and heterogeneity of myxoid/round cell liposarcomas on T2-WI were associated with metastatic relapse in univariate analysis. • A radiomics score based on 3 selected and weighted radiomics features was a strong and independent prognostic factor for metastatic relapse-free survival. • The best prediction of metastatic relapse-free survival for myxoid/round cell liposarcomas was achieved by combining the radiomics score to relevant radiological features.

Double minute chromosomes harboring MDM2 amplification in a pediatric atypical lipomatous tumor

Adipocytic tumors are rare in children and are mostly benign. Less than 25 cases of pediatric well-differentiated liposarcoma (WDLPS), atypical lipomatous tumors (ALT), and dedifferentiated liposarcoma (DDLPS) have been reported. Among them, only three cases were genetically analyzed. We describe the genetic features of a rapidly growing adipose tumor that occurred in the thigh of a 7-year-old girl. Histologically, it was composed of mature adipocytic cells with a few atypia. Molecular analysis showed high-level amplification of the 12q13-21 region including MDM2 among 64 amplified genes. MDM2 amplification is a diagnostic hallmark of ALT/WDLPS/DDLPS. In adult cases, it is typically located in ring or giant marker chromosomes. In the present case, extra-copies of MDM2 were located on double minute chromosomes (dmin). This raised the hypothesis of dmin being precursors of adult's rings and giant markers and may provide indications for a better understanding of the mechanisms of adipose tumor oncogenesis.

Protein Degradation and the Pathologic Basis of Disease

The abundance of any protein is determined by the balance of protein synthesis and protein degradation. Regulated protein degradation has emerged as a powerful means of precisely controlling individual protein abundance within cells and is largely mediated by the ubiquitin-proteasome system (UPS). By controlling the levels of key regulatory proteins, the UPS contributes to nearly every aspect of cellular function. The UPS also functions in protein quality control, rapidly identifying and destroying misfolded or otherwise aberrant proteins that may be toxic to cells. Increasingly, we understand that dysregulation of protein degradation pathways is critical for many human diseases. Conversely, the versatility and scope of the UPS provides opportunities for therapeutic intervention. In this review, we will discuss the basic mechanisms of protein degradation by the UPS. We will then consider some paradigms of human disease related to protein degradation using selected examples. Finally, we will highlight several established and emerging therapeutic strategies based on altering pathways of protein degradation.

Limited Role of TP53 and TP53-Related Genes in Myxoid Liposarcoma

Aims

Circumstantial evidence suggests that genetic changes may lead to tumor progression within the myxoid liposarcoma tumors (MLTs) carrying non-random chromosomal translocation t(12;16).

Methods

To address this subject an immunophenotypic analysis, applying antibodies against proteins encoded by TP53, MDM2 and CDK4 genes, complemented by molecular analysis of eight suitable cases, was performed on 104 consecutive cases. Chromosomal translocations were assessed either by cytogenetic analysis or by RT-PCR in 9 suitable cases and chimeric transcripts were found in all cases but two pleomorphic liposarcomas.

Results

Based on immunophenotyping and tumor site, the case material consisted of three groups. The first one was made up of 92 non-retroperitoneal cases carrying a null p53, mdm2, cdk4 immunophenotype, which remained unchanged over the time of recurrences and along the gamut of histologic subtypes. The second group was represented by five p53+, mdm2-, cdk4- non-retroperitoneal cases, 4 of which were further analysed by PCR-SSCP for p53 mutation. The im-munophenotipic profile of these cases, complemented by the molecular findings, supported a role of TP53 in tumor progression in three high-grade MLTs. The third group, consisting of 7 retroperitoneal cases, showed a heterogeneous immunophenotype, sharing immunophenotypic and molecular features with the well-differentiated/evoluted (dedifferentiated) liposarcoma group.

Conclusions

TP53 mutations seem to play a role in tumor progression in a few cases of MLTs (2.8%) showing more aggressive histologic characteristics. The unexpected finding that a number of retroperitoneal LMTs display the immunophenotypic profile of the well differentiated/evoluted (dedifferentiated) liposarcomas, deserves further investigation.

Preclinical evaluation of potential therapeutic targets in dedifferentiated liposarcoma

Sarcomas are rare cancers with limited treatment options. Patients are generally treated by chemotherapy and/or radiotherapy in combination with surgery, and would benefit from new personalized approaches. In this study we demonstrate the potential of combining personal genomic characterization of patient tumors to identify targetable mutations with in vitro testing of specific drugs in patient-derived cell lines. We have analyzed three metastases from a patient with high-grade metastatic dedifferentiated liposarcoma (DDLPS) by exome and transcriptome sequencing as well as DNA copy number analysis. Genomic aberrations of several potentially targetable genes, including amplification of KITLG and FRS2, in addition to amplification of CDK4 and MDM2, characteristic of this disease, were identified. We evaluated the efficacy of drugs targeting these aberrations or the corresponding signaling pathways in a cell line derived from the patient. Interestingly, the pan-FGFR inhibitor NVP-BGJ398, which targets FGFR upstream of FRS2, strongly inhibited cell proliferation in vitro and induced an accumulation of cells into the G0 phase of the cell cycle. This study indicates that FGFR inhibitors have therapeutic potential in the treatment of DDLPS with amplified FRS2.

Metastatic Liposarcoma of the Skull Base: A Case Report and Review of Literature

BACKGROUND AND IMPORTANCE

Myxoid liposarcoma is not an uncommon form of sarcoma. However, it usually affects the lower extremity long bones. Scapular involvement is extremely rare, as is a metastasis to the parasellar region. We present a case of liposarcoma of the skull base originating in the scapular region and metastasizing to the sellar and parasellar regions and provide a review of the pertinent literature.

CLINICAL PRESENTATION

A 43-year-old female patient diagnosed with left scapular myxoid liposarcoma was treated with surgical resection. She had clear resection margins and was treated pre- and postoperatively with radiotherapy to the region. She remained asymptomatic for 2 years following surgery, after which she abruptly developed diplopia with right lateral gaze. There were no symptoms of raised intracranial pressure or impaired vision. Her examination was normal apart from complete right sixth nerve palsy. Imaging studies of the brain showed a large mass in the clivus eroding into the floor of the sella, encircling the right internal carotid artery in the cavernous sinus. The mass also displaced the sellar contents superiorly. An endonasal, endoscopic skull base approach was undertaken, and a subtotal resection was performed in an effort to avoid multiple cranial nerve pareses.

CONCLUSION

Our literature search revealed that this case report is the first to document liposarcoma metastasis to the skull base originating from the scapular region. Subtotal surgical resection resulted in minimal improvement of the patient's sixth nerve palsy. Postoperative radiation was undertaken. A multidisciplinary approach on an individual patient basis is recommended.

Dedifferentiated Components Versus Well-differentiated Components in Dedifferentiated Lip sarcoma: A Comparative Study of Their Proliferative Activity and Interphase Cytogenetics Using MIB-1 Immunostaining and Fluorescence in Situ Hybridization

We retrospectively analyzed the proliferative activity and the centromeric copy number of chromosomes 8, 12, and 17 in both well-differentiated components and dedifferentiated ones of 10 dedifferentiated lip sarcoma cases by using MIB-1 immunostaining and fluorescence in situ hybridization (FISH) on the paraffin-embedded tissue specimens. The MIB1 labeling index (LI) in dedifferentiated components was higher than that in the well-differentiated components (p<.01). Chromosomal aberrations such as gains in chromosomes 8, 12, and 17 were found in two dedifferentiated components of the seven cases in which signals were detected. The most frequent aberrations were a gain in chromosome 17 (cases 2 and 10), followed by gains in chromosomes 8 (case 10) and 12 (case 2). In contrast, no chromosomal aberrations were observed in any of the eight well-differentiated components in which signals were detected. Based on these findings, chromosomal aberrations in the dedifferentiated components may reflect aggresive tumor progression in dedifferentiated lip sarcoma.

Liposarcomas of the posterior mediastinum: clinicopathologic study of 18 cases

Sarcomas of the posterior mediastinum are rare and correspond mostly to neurogenic tumors. We studied 18 cases of liposarcoma presenting in the posterior mediastinum; because of their unusual location, some of these tumors posed difficulties for diagnosis. There were 11 men and 7 women aged 29-87 years (mean: 57). The tumors were large lobulated masses ranging from 6 to 30 cm in greatest diameter (median: 15 cm). Symptoms included cough, dysphagia, and chest pain. Four patients were asymptomatic and the tumors were discovered incidentally on chest X-rays. Histologically, 10/18 (55%) cases were atypical lipomatous tumor/well-differentiated liposarcoma, one of which harbored a smooth muscle component (lipoleiomyosarcoma); 3/18 (16%) were de-differentiated liposarcoma, one of which also harbored a smooth muscle component; 3/18 (16%) were myxoid/round cell liposarcoma; and 2/18 (11%) were pleomorphic liposarcoma. The cases of well-differentiated liposarcoma were mostly of the sclerosing type; however, five of them also showed prominent myxoid stroma closely resembling myxoid liposarcoma. Immunohistochemistry was performed in selected cases; 4/8 cases tested showed focal positivity for S-100 protein and 5/8 cases showed nuclear positivity for MDM-2. The three cases of myxoid liposarcoma were all negative for MDM2. Both cases of lipoleiomyosarcoma showed positivity for SMA and desmin in the smooth muscle component. FISH was performed in two cases of well-differentiated liposarcoma and high levels of amplification of MDM2 at 12q13-15 were observed; the CHOP translocation at 12q13.1-q13.2 was absent in both cases. Complete surgical excision was performed in 11 cases; however, negative surgical margins were achieved only in four. Clinical follow-up ranging from 1 to 192 months (median 28 months) was available for 13 patients. Two patients with myxoid/round cell liposarcoma died of tumor after 4 months and 3 years, respectively. Both had widely disseminated metastatic disease at the time of death. Six patients (6/10) with well-differentiated liposarcoma were alive and well with no evidence of disease (at 4, 7, 12, 15, and 25 months) and three (3/10) were alive with disease (at 3, 4, and 6 months). One patient with well-differentiated liposarcoma had multiple recurrences and a liver metastasis after 14 years; however, the patient was alive and well at 16 years. Five patients were lost to follow-up. In general, the biologic behavior of liposarcomas in the posterior mediastinum seems to correlate well with the histologic subtype and mirrors that of their counterpart in the retroperitoneum.

Whole genome analyses of a well-differentiated liposarcoma reveals novel SYT1 and DDR2 rearrangements

Liposarcoma is the most common soft tissue sarcoma, but little is known about the genomic basis of this disease. Given the low cell content of this tumor type, we utilized flow cytometry to isolate the diploid normal and aneuploid tumor populations from a well-differentiated liposarcoma prior to array comparative genomic hybridization and whole genome sequencing. This work revealed massive highly focal amplifications throughout the aneuploid tumor genome including MDM2, a gene that has previously been found to be amplified in well-differentiated liposarcoma. Structural analysis revealed massive rearrangement of chromosome 12 and 11 gene fusions, some of which may be part of double minute chromosomes commonly present in well-differentiated liposarcoma. We identified a hotspot of genomic instability localized to a region of chromosome 12 that includes a highly conserved, putative L1 retrotransposon element, LOC100507498 which resides within a gene cluster (NAV3, SYT1, PAWR) where 6 of the 11 fusion events occurred. Interestingly, a potential gene fusion was also identified in amplified DDR2, which is a potential therapeutic target of kinase inhibitors such as dastinib, that are not routinely used in the treatment of patients with liposarcoma. Furthermore, 7 somatic, damaging single nucleotide variants have also been identified, including D125N in the PTPRQ protein. In conclusion, this work is the first to report the entire genome of a well-differentiated liposarcoma with novel chromosomal rearrangements associated with amplification of therapeutically targetable genes such as MDM2 and DDR2.

Adipose and myxoid tumors of childhood and adolescence

Adipose and myxoid tumors in children are an unusual and challenging group of neoplasms that have some unique aspects in contrast to these tumors in adults. Less than 10% of soft tissue neoplasms in the 1st 2 decades of life have an adipose phenotype and most are benign. The most common are various types of lipoma and lipoblastoma. Liposarcoma in young patients is rare and has a distinctive distribution of histologic subtypes, including classic myxoid liposarcoma, and unusual variants, such as pleomorphic-myxoid liposarcoma. Pathologic examination enhanced by adjunct techniques, such as immunohistochemistry and cytogenetic or molecular genetic studies, is useful for classification of difficult cases. Myxoid tumors can overlap with adipose tumors and are included in this review because of the morphologic similarities and importance of diagnostic accuracy. This article reviews the clinicopathologic features of adipose and myxoid tumors with an emphasis on the unique aspects of these neoplasms in children and adolescents and the differential diagnosis.

Contributions of cytogenetics and molecular cytogenetics to the diagnosis of adipocytic tumors

Over the last 20 years, a number of tumor-specific chromosomal translocations and associated fusion genes have been identified for mesenchymal neoplasms including adipocytic tumors. The addition of molecular cytogenetic techniques, especially fluorescence in situ hybridization (FISH), has further enhanced the sensitivity and accuracy of detecting nonrandom chromosomal translocations and/or other rearrangements in adipocytic tumors. Indeed, most resent molecular cytogenetic analysis has demonstrated a translocation t(11;16)(q13;p13) that produces a C11orf95-MKL2 fusion gene in chondroid lipoma. Additionally, it is well recognized that supernumerary ring and/or giant rod chromosomes are characteristic for atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma, and amplification of 12q13–15 involving the MDM2, CDK4, and CPM genes is shown by FISH in these tumors. Moreover, myxoid/round cell liposarcoma is characterized by a translocation t(12;16)(q13;p11) that fuses the DDIT3 and FUS genes. This paper provides an overview of the role of conventional cytogenetics and molecular cytogenetics in the diagnosis of adipocytic tumors.

Doxorubicin resistance in a novel in vitro model of human pleomorphic liposarcoma associated with alternative lengthening of telomeres

Soft tissue sarcomas are a diverse set of fatal human tumors where few agents have demonstrable clinical efficacy, with the standard therapeutic combination of doxorubicin and ifosfamide showing only a 25% to 30% response rate in large multi-institutional trials. Although liposarcomas are the most common histologic form of adult soft tissue sarcomas, research in this area is severely hampered by the lack of experimentally tractable in vitro model systems. To this end, here we describe a novel in vitro model for human pleomorphic liposarcoma. The cell line (LS2) is derived from a pleomorphic liposarcoma that uses the alternative lengthening of telomeres (ALT) mechanism of telomere maintenance, which may be important in modulating the response of this tumor type to DNA-damaging agents. We present detailed baseline molecular and genomic data, including genome-wide copy number and transcriptome profiles, for this model compared with its parental tumor and a panel of liposarcomas covering multiple histologies. The model has retained essentially all of the detectable alterations in copy number that are seen in the parental tumor, and shows molecular karyotypic and expression profiles consistent with pleomorphic liposarcomas. We also show the utility of this model, together with two additional human liposarcoma cell lines, to investigate the relationship between topoisomerase 2A expression and the sensitivity of ALT-positive liposarcomas to doxorubicin. This model, together with its associated baseline data, provides a powerful new tool to develop treatments for this clinically poorly tractable tumor and to investigate the contribution that ALT makes to modulating sensitivity to doxorubicin.

Cytogenetic and real-time quantitative reverse-transcriptase polymerase chain reaction analyses in pleomorphic rhabdomyosarcoma

Pleomorphic rhabdomyosarcoma (PRMS) is a rare variant of rhabdomyosarcoma that occurs mostly in adults. A few cytogenetic studies of PRMS have been reported, but no consistent specific chromosome aberrations were detected. We herein report a cytogenetic study of three cases of pleomorphic rhabdomyosarcoma using a conventional G-banded karyotyping analysis. The three cases appeared to exhibit an extremely complex karyotype with numeric and structural rearrangements. Although the three cases displayed several common aberrations, including -2, -4, -9, -13, -14, -15, -19, -21, add(X)(p11), add(1)(q11), add(7)(p11), and add(13)(p11), no recurrent characteristic chromosomal aberrations could be detected. In addition, among these cases and seven other cases of previously reported PRMS, the most frequent chromosomal alterations were -2, -13, -14, -15, -16, and -19. No obviously consistent structural alterations can be found in these 10 PRMS cases, however, thereby suggesting that it is difficult to confirm whether these complex karyotypes correlated with the diagnosis or clinical outcome in PRMS. In this study, we detected MyoD1 and myogenin gene transcripts at the mRNA level in four cases of PRMS together with other soft-tissue sarcomas, including seven cases of malignant fibrous hitiocytoma, five cases of liposacroma, and three cases of leiomyosacroma using a real-time quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. High-level expressions of MyoD1 and myogenin gene transcripts were determined in all cases of PRMS. In contrast, the other non-PRMS sarcomas showed either no expression or extremely weak expressions for both genes. Our findings suggest that the detections of MyoD1 and myogenin transcripts using real-time quantitative RT-PCR, combined with immunohistochemical stains, are extremely sensitive and useful for the diagnosis of PRMS.

Analysis of CHOP rearrangement in pleomorphic liposarcomas using fluorescence in situ hybridization

Pleomorphic liposarcoma (PLS) is an aggressive subtype of liposarcoma composed of high-grade sarcoma with pleomorphic lipoblasts. PLS usually exhibits a heterogeneous histology and sometimes has a myxoid or round cell area similar to myxoid/round cell liposarcomas (MLS/RCs). Using fluorescence in situ hybridization (FISH) analysis, we investigated the existence of CHOP split signals in various histological areas of PLS including the MLS/RC-like feature and also estimated the distribution of various signals with polyploidy and amplification. Moreover, to detect CHOP fusion transcripts we performed nested reverse transcription-polymerase chain reaction (RT-PCR). Seven PLSs and three MLS/RCs were selected for FISH analysis using the locus-specific indicator CHOP (12q13) dual color, break apart probe (Vysis, USA). The FISH analysis was applied to formalin-fixed, paraffin-embedded tissue sections of representative areas in all cases. Six of seven PLS cases showed the CHOP split signal ranging from 0.5% to 3% of counted nuclei, while all cases of MLS/RC exhibited CHOP rearrangement in more than 50% of counted nuclei. All cases of PLS showed a varied distribution of extra signals with polyploidy and amplification in each histological area. No CHOP fusion transcript was found in any case of PLS by nested RT-PCR. A CHOP rearrangement in PLS should be recognized only as a representative part of complex karyotypes, because the number of cells with split signals was minute compared with that of MLS/RC, and the signals were found in any area despite their histological differences. The cytogenetic background of PLS and that of MLS/RC are obviously different despite histological similarity.

Heterogeneous in vitro effects of doxorubicin on gene expression in primary human liposarcoma cultures

BACKGROUND

Doxorubicin is considered one of the most potent established chemotherapeutics in the treatment of liposarcoma; however, the response rates usually below 30%, are still disappointing. This study was performed to identify gene expression changes in liposarcoma after doxorubicin treatment.

METHODS

Cells of 19 primary human liposarcoma were harvested intraoperatively and brought into cell culture. Cells were incubated with doxorubicin for 24 h, RNA was isolated and differential gene expression was analysed by the microarray technique.

RESULTS

A variety of genes involved in apoptosis were up and down regulated in different samples revealing a heterogeneous expression pattern of the 19 primary tumor cell cultures in response to doxorubicin treatment. However, more than 50% of the samples showed up-regulation of pro-apoptotic genes such as TRAIL Receptor2, CDKN1A, GADD45A, FAS, CD40, PAWR, NFKBIA, IER3, PSEN1, RIPK2, and CD44. The anti-apoptotic genes TNFAIP3, PEA15, Bcl2A1, NGFB, and BIRC3 were also up-regulated. The pro-apoptotic CD14, TIA1, and ITGB2 were down-regulated in more than 50% of the tumor cultures after treatment with doxorubicin, as was the antiapoptotic YWHAH.

CONCLUSION

Despite a correlation of the number of differentially regulated genes to the tumor grading and to a lesser extent histological subtype, the expression patterns varied strongly; however, especially among high grade tumors the responses of selected apoptosis genes were similar. The predescribed low clinical response rates of low grade liposarcoma to doxorubicin correspond to our results with only little changes on gene expression level and also divergent findings concerning the up- and down-regulation of single genes in the different sarcoma samples.

Excellent Local Control Rates and Distinctive Patterns of Failure in Myxoid Liposarcoma Treated With Conservation Surgery and Radiotherapy

PURPOSE

To evaluate the local control rates and patterns of metastatic relapse in patients with localized myxoid liposarcoma treated with conservation surgery and radiotherapy (RT).

PATIENTS AND METHODS

Between 1960 and 2003, 127 patients with non-metastatic myxoid liposarcoma were treated with conservation surgery and RT at our institution. The median patient age was 39 years (range, 14-79 years). Of the 127 patients, 46% underwent preoperative RT (median dose, 50 Gy) and 54% underwent postoperative RT (median dose, 60 Gy). Also, 28% received doxorubicin-based chemotherapy as a part of their treatment.

RESULTS

The median follow-up was 9.1 years. The overall survival rate at 5 and 10 years was 87% and 79%, respectively. The corresponding disease-free survival rates were 81% and 73%. The local control rate at > or =5 years was 97%. The actuarial rate of distant metastases at 5 and 10 years was 15% and 24%, respectively. Of the 27 patients who developed distant metastases, 48% did so in the retroperitoneum, 22% in other extrapulmonary soft tissues, 22% in the lung, 15% in bone, and 4% in the liver.

CONCLUSION

The results of our study have shown that RT and conservation surgery for localized myxoid liposarcoma provide excellent local control. Distant metastatic relapse tended to occur in the retroperitoneum and other nonpulmonary soft tissues. Therefore, staging and surveillance imaging should include the abdomen and pelvis, as well as the thorax, for patients with localized myxoid liposarcoma.

Imaging characteristics of deep-seated lipomatous tumors: intramuscular lipoma, intermuscular lipoma, and lipoma-like liposarcoma

BACKGROUND

Lipoma-like liposarcomas mimic deep-seated lipomas in regard to imaging as well as histological findings and occasionally cause problems concerning diagnosis and treatment. The differences in the imaging findings among these lesions are not well defined. The purpose of this study was to elucidate the differences among the deep-seated adipocytic neoplasms including intramuscular lipoma, intermuscular lipoma, and lipoma-like liposarcoma.

METHODS

The imaging and clinicopathological findings of 40 intramuscular lipomas, 27 intermuscular lipomas, and 22 lipoma-like liposarcomas were evaluated, and the possibilities in the differential diagnosis were assessed.

RESULTS

Although the most frequent symptom was a palpable mass, swelling was a common symptom of intramuscular lipomas and lipoma-like liposarcomas. Imaging studies revealed dumbbell-shaped appearances among intermuscular lipomas, whereas spherical masses were characteristic of intramuscular lipomas and lipoma-like liposarcomas. Computed tomography and magnetic resonance imaging revealed fatty lesions containing streaky structures in benign lesions, and CT revealed foci of hazy amorphous density, representing spindle cell proliferation, in lipoma-like liposarcoma. Although streaky structures corresponding to entrapped muscle fibers were thick and occasionally interrupted in intramuscular lipomas, the streaky structures corresponding to areolar fibrous tissue were thin and were usually not interrupted in intermuscular lipomas. In lipoma-like well-differentiated liposarcomas, thick streaks represented entrapped muscle fibers, and thin streaks represented fibrous tissue or neoplastic spindle cell proliferation.

CONCLUSIONS

The imaging findings are helpful and often afford almost pathognomonic evidence of these lesions and could help with the selection of appropriate surgery.

Incidence patterns of soft tissue sarcomas, regardless of primary site, in the surveillance, epidemiology and end results program, 1978-2001: An analysis of 26,758 cases

Soft tissue sarcomas (STS) are a heterogeneous group of uncommon tumors that show a broad range of differentiation that may reflect etiologic distinction. Routine tabulations of STS are not morphology-specific. Further, the lack of inclusion of sarcomas arising in all organs in most standard evaluations underestimates the true rates. We analyzed the 1978-2001 Surveillance, Epidemiology and End Results program incidence rates of STS regardless of primary site, except bones and joints, using the 2002 criteria of the WHO classification. There were 26,758 cases available for analysis. Leiomyosarcomas accounted for 23.9%, malignant fibrous histiocytomas 17.1%, liposarcomas 11.5%, dermatofibrosarcomas 10.5%, rhabdomyosarcomas 4.6% and angiosarcomas 4.1%. Almost half (47.9%) of the sarcomas arose in the soft tissues, 14.0% in the skin and 7.0% in the uterus. Overall, incidence rates were highest among black women (6.26/100,000 woman-years) and the lowest among white women (4.60/100,000). Age-adjusted rates increased at 1.2% and 0.8% per year among white males and females, respectively, both trends statistically significant, while rates among blacks declined slightly. About 40% of leiomyosarcomas among women were uterine in origin, with a black/white rate ratio of 1.7. This rate ratio increased to 2.0 when we accounted for the lower prevalence of intact uteri among black compared to white women. Total STS rates rose exponentially with age. Rates for both uterine leiomyosarcoma and dermatofibrosarcoma increased rapidly during the childbearing years, peaking at about age 40 and 50, respectively. Incidence patterns of STS varied markedly by histologic type, supporting the notion that these tumors may be etiologically distinct.

Alteration of chromosome positioning during adipocyte differentiation

Chromosomes are highly restricted to specific chromosome territories within the interphase nucleus. The arrangement of chromosome territories is non-random, exhibiting a defined radial distribution as well as a preferential association with specific nuclear compartments, which indicates a functional role for chromosome-territory organization in the regulation of gene expression. In this report, we focus on changes in adipocyte differentiation that are related to a specific chromosomal translocation associated with liposarcoma tumorigenesis, t(12;16). We have examined the relative and radial positioning of the chromosome territories of human chromosomes 12 and 16 during adipocyte differentiation, and detected a close association between the territories of chromosomes 12 and 16 in differentiated adipocytes, an association not observed in preadipocytes. Although further studies are required to elucidate the underlying reasons for the adipocyte-specific translocation of chromosomes 12 and 16, our observations indicate that alteration of relative chromosome positioning might play a key role in the tumorigenesis of human liposarcomas. In addition, these results demonstrate the potential impact of higher order chromatin organization on the epigenetic mechanisms that control gene expression and gene silencing during cell differentiation.

Monosomy 22 as a diagnostic aid in a case of late recurrence of adult granulosa cell tumor of the ovary

Cytogenetic analysis of a case of metastatic granulosa cell tumor recurring 21 years after oophorectomy revealed monosomy 22. This anomaly, typical of granulosa cell tumor, coupled with the pathologic and immunophenotypic findings assisted in establishing the proper diagnosis of this lesion in the absence of the original histopathologic slides.

Pleomorphic liposarcoma of the uterus: case report and literature review

A 62-year-old woman with a history of breast carcinoma being treated with tamoxifen presented with a rapidly enlarging pelvic mass. Imaging studies suggested a uterine leiomyoma with possible sarcomatous transformation. Laparotomy revealed a 15-cm, oval, well-circumscribed mass emanating from the posterior cervix and left uterosacral ligament. The tumor had a variegated fleshy, tan, myxoid, and necrotic sectioned surface. Microscopic examination revealed a variety of patterns and cell types characteristic of liposarcoma that included myxoid/round cell, storiform/pleomorphic, epithelioid, and spindle cell areas. Lipogenic areas exhibited a "crow's feet" vasculature and characteristic lipoblasts. The tumor cells were highly pleomorphic with numerous mitotic figures, some of them atypical. The tumor cells were immunoreactive for vimentin, estrogen receptors, and S-100. The tumor recurred 9 months postoperatively. Although a variety of uterine tumors have been associated with tamoxifen treatment, this appears to be the first example of tamoxifen-associated uterine liposarcoma.

Pediatric-type sarcomas in adult patients

Sarcomas included in the broad group of small round-cell tumors (SRCT) and some non-SRCT lesions that typically are seen in pediatric-age patients can rarely occur in adults. However, there are differences in the anatomic sites that are involved and the prognosis in these two patient groups. The diagnosis of pediatric-type sarcomas in adults is often challenging because of the unusual contextual clinical setting and morphologic features. Immunohistochemical studies have greatly facilitated this process. Moreover, limited biomolecular studies that have been conducted have demonstrated comparable cytogenetic alterations in adults and children with pediatric-type tumors. They also have raised interesting questions concerning possible biological bases for differences in clinical behavior in the two cohorts. This review focuses on the morphological, immunohistochemical, and molecular characteristics of childhood-type sarcomas that affect adults, with emphasis on possible pitfalls in differential diagnosis.

Different mRNA expression profile during tumor progression in a well-differentiated liposarcoma--A microdissection approach

Like malignant fibrous histiocytoma (MFH), dedifferentiated liposarcoma represents a distinct subtype of liposarcoma and is characterized by an abrupt transition from well-differentiated liposarcoma (WDL) to highgrade dedifferentiated liposarcoma (DDL) . In addition, specific cytogenetic aberrations support the close biological relationship between WDL and DDL. Recent observations indicated the significance of cell cycle aberrations in tumor progression from the low-malignant, well differentiated to its dedifferentiated form, the prognosis of which is poor. Thus, alterations of mdm2 and p53 genes belong to the most frequently reported alterations in these two subtypes of liposarcoma. In previous investigations, we reported that loss of heterozygosity at the Rb gene locus, telomerase activity, hTERT, and c-Myc expression were associated with tumor progression in liposarcomas. In this study, we report on a case of a WD/DDL, in which both tumor components were separated using laser microdissection (P.A.L.M.) for the investigation of hTERT mRNA expression on a LightCycler. Macroscopically selected and histologically proven cryosections of low malignant and highly malignant tumor areas were cytogenetically investigated to confirm the diagnosis and to find additional chromosomal alterations with tumor progression.

Neocentromeres: role in human disease, evolution, and centromere study

The centromere is essential for the proper segregation and inheritance of genetic information. Neocentromeres are ectopic centromeres that originate occasionally from noncentromeric regions of chromosomes. Despite the complete absence of normal centromeric alpha-satellite DNA, human neocentromeres are able to form a primary constriction and assemble a functional kinetochore. Since the discovery and characterization of the first case of a human neocentromere in our laboratory a decade ago, 60 examples of constitutional human neocentromeres distributed widely across the genome have been described. Typically, these are located on marker chromosomes that have been detected in children with developmental delay or congenital abnormalities. Neocentromeres have also been detected in at least two types of human cancer and have been experimentally induced in Drosophila. Current evidence from human and fly studies indicates that neocentromere activity is acquired epigenetically rather than by any alteration to the DNA sequence. Since human neocentromere formation is generally detrimental to the individual, its biological value must lie beyond the individual level, such as in karyotype evolution and speciation.

TLS-CHOP target gene DOL54 expression in liposarcomas and malignant fibrous histiocytomas

Downstream of the gene for the liposarcoma-associated fusion oncoprotein 54 (DOL54) is a target gene of the myxoid liposarcoma and round cell liposarcoma (M-LPS/RC-LPS) oncogene, TLS/FUS-CHOP. The DOL54 gene product is closely associated with adipogenic differentiation. DOL54 overexpression resulted in tumorigenicity when Chinese Hamster Ovary (CHO) cells were injected subcutaneously into nude mice. The biological significance of DOL54 expression for human malignant soft tissue tumors, however, has not yet been investigated. We examined TLS-CHOP and DOL54 expression in M-LPS/RC-LPS, well-differentiated liposarcoma and malignant fibrous histiocytoma (MFH), a tumor whose cellular origin has not been determined. We observed DOL54 expression in 50% of M-LPS/RC-LPS cases (in which TLS-CHOP was also expressed) and 33% of MFH cases, suggesting that a portion of MFH lesions may either derive from adipocytic precursor cells or have the potential to undergo adipogenic differentiation. In this manner, M-LPS/RC-LPS and MFH lesions may share tumorigenic characteristics, resulting from the unscheduled expression of DOL54.

Distinct chromosomal imbalances in pleomorphic and in high-grade dedifferentiated liposarcomas

Using comparative genomic hybridization, DNA copy number changes were studied in 14 pleomorphic liposarcomas and compared to those detected in high-grade areas of 9 dedifferentiated liposarcomas. A total of 251 gains and 84 losses were detected. The most frequent gains involved subregions of chromosomal arms 12q and 20q (70% each), 5p (57%), 6q and 9q (52% each), 1q, 7p and 17p (48% each), 1p (43%), 6p and 17q (39% each), 20p and 22q (35% each) as well as 7q and 12p (30% each). The same subregions were also affected by 30 high level amplifications. The most frequent losses were found in subregions of chromosomal arms 13q (35%) as well as 11q and 12p (30% each). Overall, gains of chromosomal material were more frequent than losses (p < 0.001). There were significant differences in the frequency and distribution of recurrent chromosomal imbalances between pleomorphic liposarcomas and the dedifferentiated areas of dedifferentiated liposarcomas. Gains of chromosomal material detected predominantly in pleomorphic liposarcomas involved subbands 5p13-p15 (p < 0.010), 1p21 (p < 0.019), 1q21-q22 (p < 0.040) and 7q22 (p < 0.049). Conversely, high level amplifications within chromosomal subregion 12q13-q21 were only found in the dedifferentiated components of dedifferentiated liposarcomas (p < 0.001). Overall, both gains and the less pronounced losses of chromosomal material were more frequent in pleomorphic than in dedifferentiated liposarcomas (p < 0.001 and p < 0.025, respectively). These results show that pleomorphic liposarcomas display a considerable number of recurrent chromosomal imbalances that are essentially different from those present in high-grade areas of dedifferentiated liposarcomas. Therefore, genetic data are considered as a helpful diagnostic adjunct for the discrimination between these 2 types of liposarcoma. The overall higher frequency of chromosomal imbalances in pleomorphic as compared to dedifferentiated liposarcomas could account for the more aggressive biological behavior of pleomorphic relative to dedifferentiated liposarcoma types.

A well-differentiated liposarcoma with a new type of chromosome 12-derived markers

Well-differentiated liposarcomas (WDLPS) are cytogenetically characterized by the presence of supernumerary ring or giant rod marker chromosomes. These supernumerary chromosomes are composed of amplified sequences from chromosome 12 (12q14 approximately 15) in association with amplified segments from various other chromosomes, and contain alterations of the alpha satellite sequences. We report a case of WDLPS of the lipoma-like and sclerosing subtype that contains a novel type of supernumerary marker chromosome. Instead of rings or giant rods, these cells had three apparently identical copies of a subtelocentric supernumerary marker with a size and shape similar to C-group chromosomes. Fluorescence in situ hybridization analysis revealed that the markers were composed of amplified material from 12q14 approximately 15, including the genes MDM2 and CDK4. Similar to the rings and giant rods observed in other WDLPS cases, these unusual markers had no alpha satellite repeats at the primary constriction site, but centromeric activity could be demonstrated by using anti-centromere protein C antibodies. These findings show that the supernumerary markers of WDLPS may be variable in size and shape, but consistently share the same genomic structure, specifically 12q amplified sequences together with centromere alterations, and underline the importance of molecular methods in the diagnosis of adipose tissue tumors.

LiSa-2, a novel human liposarcoma cell line with a high capacity for terminal adipose differentiation

LiSa-2 is a stable cell line derived from a poorly differentiated, pleomorphic liposarcoma. In serum-containing medium, LiSa-2 cells are fibroblastoid and rapidly dividing. In a serum-free, chemically defined culture medium containing physiological concentrations of insulin, triiodothyronine and cortisol, LiSa-2 cells divide slower and, extensively storing fat, acquire adipocyte morphology. In contrast to fibroblastoid LiSa-2 cells, these adipocyte-like LiSa-2 cells highly express transcripts for peroxisome proliferator-activated receptor-gamma, lipoprotein lipase, fatty acid synthetase, hormone-sensitive lipase, adipocyte most abundant gene transcript-1, glycerol-3-phosphate-dehydrogenase and the insulin-sensitive glucose transporter-4, all of which are specific for differentiated adipocytes. However, leptin mRNA expression was demonstrated only after preventing DNA methylation by incorporation of 5-aza-deoxycytidine into cellular DNA. Functionally, adipocyte-like LiSa-2 cells show increased insulin-dependent glucose uptake and lipid synthesis and are sensitive to lipolytic agents. This cell line may serve as an in vitro model for studying the regulation of human liposarcoma differentiation and for screening drugs for induction of differentiation-associated growth arrest in liposarcomas.

Specificity of TLS-CHOP rearrangement for classic myxoid/round cell liposarcoma: absence in predominantly myxoid well-differentiated liposarcomas

Myxoid liposarcoma (LS), the most common subtype of LS, is known to be characterized by the specific t(12;16) resulting in a TLS-CHOP fusion in almost all cases. We wished to address the following questions: (i) Is this genetic hallmark also present in other types of LS with predominant myxoid change? (ii) What is the proportion of cases with the variant EWS-CHOP fusion? (iii) What is the optimal approach for Southern blot detection of TLS breakpoints? We identified 59 LS characterized histologically by >90% myxoid component, in which frozen tissue tumor was available for DNA extraction. These 59 LS with myxoid features were divided into 2 groups: 42 LS with classic myxoid/round cell appearance (myxoid LS) and 17 well-differentiated LS (WDLS) with a predominant (>90%) myxoid component. Within the myxoid LS group, 29 tumors were low grade and 13 high grade (>20% round cell component). Among the 17 predominantly myxoid WDLS, there were 15 low grade and 2 focally high grade tumors. In addition, we selected as control group, 20 LS of other histological types with minimal or no myxoid change (17 WDLS and 3 pleomorphic LS) and 13 myxofibrosarcomas. Southern blot analysis was performed in all cases using a CHOP cDNA probe, and in all CHOP rearranged cases using a TLS cDNA probe. Probe/enzyme combinations for Southern blot analysis were CHOP exon 3-4 cDNA probe with BamHI or SacI, TLS exon 3-6 cDNA probe with BclI. All 42 cases of myxoid LS showed a CHOP rearrangement and 38 of them also had a TLS rearrangement. Among the 4 myxoid LS without Southern blot evidence of TLS rearrangement, 1 showed an EWS-CHOP fusion by Southern blotting and reverse transcriptase-polymerase chain reaction and in another case, reverse transcriptase-polymerase chain reaction detected a TLS-CHOP fusion transcript. None of the predominantly myxoid WDLS and none of the tumors included in the control group showed rearranegements with CHOP probe. In addition, 12 predominantly myxoid WDLS, 10 other LS, and 5 myxofibrosarcoma from the control group were also tested for TLS rearrangement; all were negative. The TLS-CHOP fusion is highly sensitive and specific for the entity of classic myxoid/round cell LS. Other types of LS, even with a predominant myxoid component, lack the TLS-CHOP rearrangement, confirming that they represent a genetically distinct group of LS. The prevalence of the EWS-CHOP variant fusion was approximately 2% in this series. The optimal enzyme for TLS genomic breakpoint detection is BclI.

Retroperitoneal liposarcoma with combined well-differentiated and myxoid malignant fibrous histiocytoma-like myxoid areas

To broaden the knowledge of myxoid morphology in liposarcoma, eight cases of unusual liposarcoma with combined well-differentiated and myxoid malignant fibrous histiocytoma (MFH)-like myxoid areas are reported. The tumors arose as huge retroperitoneal masses in elderly patients, except for one that occurred in the spermatic cord. Three cases had local recurrences, and one of the seven patients who were followed up had died of the tumor. Grossly, the tumors were mostly confluent and multinodular and showed a glistening myxoid appearance in variable proportions, which merged gradually into or were juxtaposed to yellow fatty or sclerotic whitish areas. Microscopically, in addition to areas of well-differentiated lipoma-like or sclerosing liposarcoma, all the tumors contained myxoid portions characterized by scattered multinucleated or bizarre giant cells and a prominent plexiform vascular pattern that resembled myxoid MFH or myxofibrosarcoma. The myxoid areas were associated with discernible lipogenesis. High-grade dedifferentiation was present in one tumor. Cytogenetically, in one case, the myxoid lesion had nonrandom chromosomal aberrations, such as ring and marker chromosomes, characteristic of a well-differentiated variant of liposarcoma. In a nested reverse transcription-polymerase chain reaction analysis using archival paraffin-embedded tissue, it was seen that none of the eight tumors with myxoid MFH-like features had TLS/FUS-CHOP fusion transcripts characteristic of myxoid and round cell liposarcomas. These clinicopathologic and molecular features suggest that the current myxoid tumors are more closely related to well-differentiated liposarcoma rather than to ordinary myxoid liposarcoma despite their unequivocal myxoid morphology. Missense point mutations of the p53 gene were detected in two (25%) cases by single-strand conformation polymorphism and sequence analyses. Immunohistochemical expressions of p53 and mdm2 were observed in 75% of the cases, in which immunoreactive tumor cells were seen more often in the myxoid MFH-like areas. Thus, altered p53 pathways, such as p53 gene mutation and mdm2-mediated inactivation of p53, may play a pathogenetic role in this form of tumor progression showing myxoid MFH-like morphology in liposarcoma, as has been suggested in dedifferentiated liposarcoma.

Molecular genetics of chromosome translocations involving EWS and related family members

Many types of sarcomas are characterized by specific chromosomal translocations that appear to result in the production of novel, tumor-specific chimeric transcription factors. Many of these show striking similarities: the emerging picture is that the amino-terminal domain of the fusion product is donated by the Ewing's sarcoma gene (EWS) or a related member from the same gene family, whereas the carboxy-terminal domain often consists of a DNA-binding domain derived from one of a number of transcription factors. Given the observation that the different translocation partners of the EWS protooncogene are associated with distinct types of sarcomas, the functional consequence of fusing EWS (or a related family member) to a different DNA-binding domain can only be understood in the context of functional studies that define the specificity of action of the different fusion products. An understanding of the molecular structure and function of these translocations provides new methods for diagnosis and novel targets for therapeutics.

Diagnostic and prognostic implications of the unfolding molecular biology of bone and soft tissue tumours

Sarcomas account for approximately 1-2% of human malignant disease and are relatively uncommon. Histopathological study of these mesenchymal tumours at light microscopic and ultrastructural level may not always provide an unambiguous diagnosis. It has become apparent with the identification of increasing numbers of tumour specific genetic alterations that (cyto) genetic evaluation could become a very helpful adjunct to histopathological assessment in reaching a correct diagnosis. Thus, once the different tumour types can be accurately identified and classified, more meaningful clinical trials can be initiated to evaluate and select optimal methods of management. In addition, an increasing awareness and understanding of the molecular changes associated with, and the genetic variability in, the various tumour groups is beginning to provide important new information about clinical progression and prognosis.

Fine mapping of an apparently targeted latent human herpesvirus type 6 integration site in chromosome band 17p13.3

An unusually high level of latent HHV-6 infection has been documented in the peripheral blood and/or bone marrow cells of a small group of patients with predominantly malignant lymphoid disorders, and in at least one healthy individual. We have shown previously in peripheral blood mononuclear cells (PBMCs) of three patients, two with a history of lymphoma and one with multiple sclerosis, a specific target site for latent integration of the full-length HHV-6 viral genome on the distal short arm of chromosome 17, in band p13.3. Fluorescence in situ hybridization (FISH) procedures were used to map more precisely the location of the viral integration site in one of those patients, relative to two known oncogenes mapped previously, namely CRK, and the more telomeric ABR oncogene. It is shown that the HHV-6 integration site is located at least 1,000 kb telomeric of ABR, and is very likely to map close to or within the telomeric sequences of 17p. This finding is significant given that human telomeric-like repeats flank the terminal ends of the HHV-6 genome. Cytogenetic studies showed evidence of karyotype instability in the peripheral blood cells infected latently.

Induction of a secreted protein by the myxoid liposarcoma oncogene

The TLS-CHOP oncoprotein, found in the majority of human myxoid liposarcomas, consists of a fusion between the transcription factor CHOP/GADD153 and the N terminus of an RNA-binding protein TLS/FUS. Clinical correlation and in vitro transformation assays indicate that the N terminus of TLS plays an important role in oncogenesis by TLS-CHOP. Until now, however, the only activity attributed to the oncoprotein is that of inhibiting the binding of transcription factors of the C/EBP class to certain adipogenic target genes, a function that TLS-CHOP shares with the nononcogenic CHOP protein. Here we report the isolation of a gene, DOL54, that is activated in primary fibroblasts by the expression of TLS-CHOP. DOL54 is expressed in the neoplastic component of human myxoid liposarcomas and increases the tumorigenicity of cells injected in nude mice. Activation of DOL54 requires an intact DNA-binding and dimerization domain in TLS-CHOP, a suitable cellular dimerization partner, and depends on the TLS N terminus. Normal adipocytic differentiation is associated with an early and transient expression of DOL54, and the gene encodes a secreted protein that is tightly associated with the cell surface or extracellular matrix. TLS-CHOP thus leads to the unscheduled expression of a gene that is normally associated with adipocytic differentiation.

Mixed-type liposarcoma of the oral cavity: a case with unusual features and a long survival

A case of mixed-type liposarcoma, which showed unusual dedifferentiation in the recurrence, is reported. The rapidly growing mass in the palate of a 60-year-old Japanese woman first revealed a combination of myxoid liposarcoma with features resembling storiform malignant fibrous histiocytoma. The recurrent neoplasm, showing an abrupt transition between myxoid and non-lipogenic parts, partially reverted to sclerosing well-differentiated liposarcoma. The patient died 10.1 years after the first operation.

Ring chromosomes in a malignant mesenchymoma

We report, for the first time, the cytogenetic and molecular genetic constitution of a human mesenchymoma. As in several other soft tissue sarcomas, supernumerary ring and rod-shaped marker chromosomes were observed next to an otherwise normal diploid karyotype. Comparative genomic in situ hybridization and whole chromosome painting experiments revealed that chromosome 1q21-q25 and 12q14-q15 sequences were amplified, and that these sequences resided on the supernumerary marker chromosomes. We assume that, in this malignant mesenchymoma, the observed chromosomal anomalies may be associated with its well differentiated liposarcomatous component.