Malignant fibrous histiocytoma: Inherited and sporadic forms have loss of heterozygosity at chromosome bands 9p21-22?evidence for a common genetic defect

Primate genome gain and loss: a bone dysplasia, muscular dystrophy, and bone cancer syndrome resulting from mutated retroviral-derived MTAP transcripts

Diaphyseal medullary stenosis with malignant fibrous histiocytoma (DMS-MFH) is an autosomal-dominant syndrome characterized by bone dysplasia, myopathy, and bone cancer. We previously mapped the DMS-MFH tumor-suppressing-gene locus to chromosomal region 9p21-22 but failed to identify mutations in known genes in this region. We now demonstrate that DMS-MFH results from mutations in the most proximal of three previously uncharacterized terminal exons of the gene encoding methylthioadenosine phosphorylase, MTAP. Intriguingly, two of these MTAP exons arose from early and independent retroviral-integration events in primate genomes at least 40 million years ago, and since then, their genomic integration has gained a functional role. MTAP is a ubiquitously expressed homotrimeric-subunit enzyme critical to polyamine metabolism and adenine and methionine salvage pathways and was believed to be encoded as a single transcript from the eight previously described exons. Six distinct retroviral-sequence-containing MTAP isoforms, each of which can physically interact with archetype MTAP, have been identified. The disease-causing mutations occur within one of these retroviral-derived exons and result in exon skipping and dysregulated alternative splicing of all MTAP isoforms. Our results identify a gene involved in the development of bone sarcoma, provide evidence of the primate-specific evolution of certain parts of an existing gene, and demonstrate that mutations in parts of this gene can result in human disease despite its relatively recent origin.

Benefits of molecular pathology in the diagnosis of musculoskeletal disease : Part II of a two-part review: bone tumors and metabolic disorders

The second part of this review, on the benefits of molecular pathology in the diagnosis disease, focuses on the genetics of bone tumors and metabolic disease. Unlike soft tissue tumors, the number of currently exploitable molecular abnormalities for diagnosing bone neoplasms is small, although the same gene rearrangements are found in primitive neuroectodermal tumor/Ewing sarcoma in both skeletal and extraskeletal sites. Compared with soft tissue tumors, genetic abnormalities, which are valuable to diagnosticians in skeletal disease, are often germline and post-zygotic aberrations rather than somatic translocations. In addition, the review highlights the range of disease entities classified as "osteoclast-rich lesions," some of which harbor germline mutations. It also addresses the importance of phosphate metabolism in skeletal disorders including phosphaturic mesenchymal tumor, vitamin D-resistant rickets, and tumoral calcinosis.

Total knee arthroplasty in a patient with Hardcastle syndrome

Diaphyseal medullary stenosis is a rare skeletal dysplasia of unknown etiology with potential autosomal dominant genetic inheritance. A variant of diaphyseal medullary stenosis has been associated with a high risk of malignant transformation, specifically in the form of malignant fibrous histiocytoma. This potential combination of diaphyseal medullary stenosis and malignant fibrous histiocytoma is known as Hardcastle syndrome. This article presents a case of a 32-year-old man with osteoarthrosis of the knee as a consequence of Hardcastle syndrome for which he underwent a total knee arthroplasty (TKA) with a satisfactory outcome. Our case demonstrates pathological and radiological signs of skull involvement, which has not previously been reported in the literature as a manifestation of this condition. We discuss the differential diagnoses of diaphyseal dysplasia that should be considered in such cases and advocate the use of a triad of preoperative radiological investigations, including early thallium isotope bone, magnetic resonance imaging, and computed tomography. We also discuss the use of long-stemmed prostheses, extramedullary femoral alignment, and the concerns of using Computer Assisted Surgery for total knee arthroplasty in patients with diaphyseal medullary stenosis.With the short-term success of TKA in Hardcastle syndrome, we found that TKA could be considered as an alternative treatment option in symptomatic patients. However, due to the fact that the potential for malignant transformation in this syndrome is unchanged by a TKA, the patient should remain under close clinical and radiological follow-up.

Diaphyseal medullary stenosis with pleomorphic malignant fibrous histiocytoma of the bone: 99mTc hydroxymethylenediphosphonate and 201Tl chloride scintigraphy findings

Diaphyseal medullary stenosis (DMS) is an extremely rare hereditary bone dysplasia, which was first described by Arnold in 1973. DMS has a high incidence of pleomorphic malignant fibrous histiocytoma (MFH). In this paper, we report the imaging findings of DMS with pleomorphic MFH of the bone, mainly describing 99mTc hydroxymethylenediphosphonate (HMDP) and thallium-201 (201Tl) chloride scintigraphy findings. On 99mTc HMDP scintigraphy, focal increased uptake area of the right femur corresponded to the area of bone marrow invasion of the tumor and bone infarction. The mechanism of the uptake of 99mTc HMDP to the extraosseous lesion was not clear. On 201Tl chloride scintigraphy, the increased uptake of the periphery of the mass seemed to reflect the aggressiveness of invasion and the cellularity.

Malignant fibrous histiocytoma of bone: analysis of genomic imbalances by comparative genomic hybridisation and C-MYC expression by immunohistochemistry

Malignant fibrous histiocytoma (MFH) of bone is a rare, highly malignant tumour. As very little is known about its genetic alterations, 26 bone MFHs were analysed by comparative genomic hybridisation (CGH). Twenty-three tumours (89%) had DNA sequence copy number changes (mean, 7.2 changes per sample). Gains were more frequent than losses (gains:losses=2.5:1). Minimal common regions for the most frequent gains were 8q21.3-qter (35%), 9q32-qter (35%), 7q22-q31 (35%), 1q21-q23 (31%), 7p12-pter (31%), 7cen-q11.2 (31%) and 15q21 (31%). Minimal common regions for the most frequent losses were 13q21-q22 (42%) and 18q12-q22 (27%). High-level amplifications were detected in 8 out of the 26 tumours (31%). The only recurrent amplifications, 1q21-q23 and 8q21.2-q22, were present in two samples (8%). As copy number increase at 8q24 (the locus of C-MYC) was frequent, the expression of C-MYC was studied by immunohistochemistry. Increased levels of c-myc protein were detected in 7 out of 21 tumours studied (33%). 81% of the samples studied both by CGH and immunohistochemistry showed concordant results. Furthermore, the findings of the present study were compared to previous publications on osteosarcoma, soft tissue MFH and fibrosarcoma of bone. Clear differences were detected in CGH aberration patterns, further supporting the concept of bone MFH as an individual bone tumour entity. Finally, the findings of the present study reflect well the high malignancy and aggressive nature of bone MFH.

The elusive multiple self-healing squamous epithelioma (MSSE) gene: further mapping, analysis of candidates, and loss of heterozygosity

The MSSE gene predisposes to multiple invasive but self-healing skin tumours (multiple self-healing epitheliomata). MSSE was previously mapped to chromosome 9q22-q31 and a shared haplotype in affected families suggested a founder mutation. We have refined the MSSE critical region (<1 cM, <1 Mb) between the zinc-finger gene ZNF169 and the Fanconi anaemia gene FANCC. By genetic mapping we have excluded ZNF169 and FANCC as well as PTCH (PATCHED) and TGFBR1 (transforming growth factor beta receptor type-1) genes. The CDC14B cell cycle phosphatase gene also lies in the region but screening of the complete coding region revealed no mutation in MSSE patients. Somatic cell hybrids created by haploid conversion of an MSSE patient's cells enabled screening of the MSSE chromosome 9 and showed no CDC14B deletion or mutation that abrogates CDC14B mRNA expression. Thus, CDC14B is unlikely to be the MSSE gene. We also report the first molecular analysis of MSSE tumours showing loss of heterozygosity of the MSSE region, with loss of the normal allele, providing the first evidence that MSSE is a tumour suppressor gene.

Local recurrence of myxofibrosarcoma is associated with increase in tumour grade and cytogenetic aberrations, suggesting a multistep tumour progression model

Myxofibrosarcoma is one of the most frequent soft tissue tumours in elderly patients, mostly arising in the extremities. Grade I lesions are only locally aggressive whereas grade II and grade III lesions have metastatic potential. The differential diagnosis contains several other (benign) myxoid soft tissue tumours. A number of sarcomas are characterised by specific cytogenetic aberrations, giving not only insight in their biological pathways; they also serve as molecular markers in difficult diagnoses. Cytogenetic data on myxofibrosarcoma are scarce with only few isolated cases described in the literature. No specific chromosomal aberrations have been detected so far. Moreover, molecular pathways in tumorigenesis and progression of myxofibrosarcoma are barely understood. We studied the clinicopathologic data and karyotypes of 32 myxofibrosarcomas using conventional banding and multicolour COmbined Binary RAtio labelling fluorescence in situ hybridisation technique. We included eight grade I, eight grade II and 16 grade III lesions. In all, 22 were primary tumours, nine were local recurrences and one a lymph node metastasis. The myxofibrosarcomas showed equal sex distribution, were mostly located at the extremities with two thirds deep-seated and had an average age of occurrence of 66 years. We found normal karyotypes in eight cases and clonal beside nonclonal aberrations in 22 cases. Complex cytogenetic anomalies were found in all grades. However, no tumour-specific chromosomal abnormalities could be withdrawn. Local recurrences showed increase in grade compared to their primary lesions. Interestingly, these recurrences showed more complex cytogenetic aberrations. Increase in grade seems to parallel increase in cytogenetic aberrations and malignant potential. Since the chromosomal aberrations found were not tumour type specific, they seem to be rather the result of secondary events in tumour progression and tumour genetic instability. Based on these findings, we suggest that tumorigenesis of myxofibrosarcoma is mainly a multistep genetic process, probably ruled by genetic instability caused by targeted checkpoint genes.

Mapping autosomal dominant progressive limb-girdle myopathy with bone fragility to chromosome 9p21-p22: a novel locus for a musculoskeletal syndrome

Progressive myopathy of a limb-girdle distribution and bone fragility is a rare autosomal dominant disorder of unknown etiology. Affected individuals, within this family, present with various combinations of progressive muscle weakness, easy fracturing, and poor healing of long bones. Additional features include premature graying with thin hair, thin skin, hernias, and clotting disorders. Electromyograms show myopathic changes and biopsies reveal non-specific myopathic changes. Skeletal radiographs demonstrate coarse trabeculation, patchy sclerosis, cortical thickening, and narrowing of medullary cavities. We report genetic mapping of this disorder to chromosome 9p21-p22 in a multigenerational family. A genome-wide scan for the disease locus obtained a maximal LOD score of 3.74 for marker GATA87E02 N (D9S1121). Haplotype analysis localized the disease gene within a 15 Mb interval flanked by markers AGAT142P and GATA5E06P. This region also localizes diaphyseal medullary stenosis with malignant fibrous histiocytoma (DMS-MFH). Identification of the disease gene will be necessary to understand the pathogenesis of this complex disorder.

Establishment and characterization of a novel myxofibrosarcoma cell line

We established a novel human myxofibrosarcoma cell line NMFH-1 and analyzed it with spectral karyotyping and comparative genomic hybridization (CGH). NMFH-1 cells are composed of two different types of cells, small, spindle-shaped mononuclear cells and bizarre multinucleated giant cells, which were maintained in vitro over 200 passages. Xenografted tumor showed typical features of myxofibrosarcoma, which included bizarre multinucleated giant cells. Cytogenetic analyses revealed complex abnormalities, including a t(17;22)(q2?2;q13), which has been found in dermatofibrosarcoma protuberans. Subsequent reverse-transcription polymerase chain reaction revealed that the cell line did not have the COL1A1-PDGFB gene fusion. Significant gains of the 1q12 approximately q23 and 8q13 approximately qter regions and loss of the 9p21 approximately pter and 13q12 regions often found in MFH were observed by CGH analysis. We investigated the origin of multinucleated giant cells in xenografted tumor through DNA in situ hybridization. In this system, the human-specific Alu sequence and the mouse L1 sequence were used as specific cell markers of identity. In situ hybridization revealed neoplastic proliferation of the multinucleated giant cells of human origin.

Leiomyosarcoma and malignant fibrous histiocytoma share similar allelic imbalance pattern at 9p

Formalin-fixed, paraffin-embedded tissue from 45 soft tissue sarcomas was analysed for allelic imbalance/loss of heterozygosity (AI/LOH) of chromosome 9. The specimens consisted of 17 cases of soft tissue leiomyosarcoma (LMS), 4 cases of cutaneous LMS, 22 cases of conventional malignant fibrous histiocytoma (MFH) and 2 cases of angiomatoid fibrous histiocytoma. All cases were categorised morphologically and immunohistochemically. DNA was microdissected from normal and neoplastic tissues. AI/LOH was performed using six microsatellite markers on the 9p region. The frequency of allelic imbalance at different loci on chromosome 9p was analysed in LMS and MFH and then compared with values previously examined in synovial sarcoma and malignant peripheral nerve sheath tumour. Although AI/LOH and microsatellite instability (MSI) were more frequent in MFH, LMS and MFH groups showed similar patterns of allelic imbalance at the 9p region. Alterations of chromosome 9p have been reported in many cell lines and tumours including LMS and MFH. 9p21 region encodes p16(INK4A) and p15(INK4B). Allelic imbalance observed at 9p 21 in this study suggests that alterations of the negative cell cycle regulators may be an important step in the pathogenesis of MFH and LMS. However, the most frequent allelic imbalance was observed at 9p24 at D9S230. Alterations of this locus were very rare in synovial sarcoma and malignant peripheral nerve sheath tumours and were absent in cutaneous LMS and angiomatoid fibrous histiocytoma. This locus may point to the existence of a genetically altered tumour suppressor gene involved in the pathogenesis of LMS and MFH. Our results support the hypothesis that MFHs may represent a morphological pathway in tumour progression of LMSs.

International nosology and classification of constitutional disorders of bone (2001)

The last International Classification of Constitutional Disorders of Bone was published in 1998. Since then rapid advances have been made in identifying the molecular changes responsible for defined conditions and new disorders are constantly being delineated. For these reasons a further update on the classification is appropriate. It has been expended to not only the osteochondrodysplasias (33 groups) but also genetically determined dysostoses (3 groups).

Malignant fibrous histiocytoma associated with diaphyseal medullary stenosis

An unusual presentation of secondary malignant fibrous histiocytoma of the femur in a patient with diaphyseal medullary stenosis is described. The patient, a 42-year-old man, presented with a painful lump in the right knee. A radiograph of the right femur showed lytic destruction. Characteristic features of longitudinal linear striations in the metaphysis and medullary stenosis in the diaphysis were observed in radiographs of the long tubular bones. A radiograph of the pelvis showed bilateral acetabular bone scleroses. After chemotherapy, surgical resection was done. On light microscopic examination, the tumor had features characteristic of malignant fibrous histiocytoma. Specimens from the diaphyseal medullary stenosis from the femur and tibia showed typical features of bone infarction. Radiographs of other members of the patient's family showed similar features of linear striation, cortical bone thickening, and acetabular sclerosis, including wavy, open growth plate of the iliac crest. The patient's aunt had died of a bone sarcoma in the shoulder region. It is important to recognize this extremely rare clinicopathologic type of diaphyseal medullary stenosis that frequently is associated with secondary high-grade sarcomas.

Genetic alterations in normal epithelium of colorectal cancer patients may be a useful indicator for subsequent metachronous tumor development

BACKGROUND

We attempted to identify areas of microsatellite alterations specific to histologically normal colorectal epithelium and to clarify the correlations among those molecular events and clinicopathologic features.

METHODS

We conducted a prospective observation study on 51 colorectal cancer patients. Preoperative blood and microdissected histologically normal colorectal epithelium and neoplastic tissues were collected. Microsatellite analyses with seven microsatellite loci were performed to examine the genetic potential of individual tumors and histologically normal colorectal epithelium.

RESULTS

In the sporadic colorectal cancer group, p53 LOH in the neoplastic epithelium had a significant correlation with the maximum tumor diameter and the preoperative serum cancer antigen 19-9 level, but not with the depth of invasion of the primary tumor. Among the patients who had p53 LOH in the histologically normal colorectal epithelium, four additional tumors were discovered within 30 months after curative surgery. For those patients, microsatellite alterations in normal colorectal epithelium were more sensitive than tumor markers.

CONCLUSIONS

For accurate LOH analysis, nonmalignant lymphocytes from blood should be used as the appropriate normal DNA sample. Focusing on the identification of high-risk patients for microsatellite alterations in histologically normal colorectal epithelium can be a useful indicator of subsequent metachronous tumor development after colorectal surgery. For accurate LOH analysis, nonmalignant lymphocytes from blood should be used as the appropriate normal DNA sample. Focusing on the identification of high-risk patients for microsatellite alterations in histologically normal colorectal epithelium can be a useful indicator of subsequent metachronous tumor development after colorectal surgery.

p16INK4A-alterations in primary angiosarcoma of the liver

BACKGROUND/AIMS

Alterations in the p16 (CDKN2/MTS-1/INK4A) gene have been implicated in the tumorigenesis of different human cancers. Recent evidence shows that transcriptional silencing as a consequence of hypermethylation of CpG islands is the predominant mechanism of p16INK4a gene inactivation in malignant epithelial tumors. This study was performed to determine whether alterations of p16 are involved in the development of angiosarcoma of the liver.

METHODS

The status of p16 was evaluated in 17 angiosarcomas of the liver by methylation-specific PCR (MSP), microsatellite analysis, DNA sequencing and immunohistochemical staining. The results obtained were correlated with histopathological variables and with patient survival.

RESULTS

Hypermethylation of the 5' CpG island of the p16 gene was found in 12 out of 17 (71%) angiosarcomas examined. Homozygous deletion at the p16 region was present in one case (6%), and loss of heterozygosity was present in two cases (12%). We failed to detect p16 gene missense mutations. The status of p16 correlated with neither histopathological factors nor with the prognosis of the patients with angiosarcomas.

CONCLUSIONS

These data suggest that inactivation of the p16 gene is a frequent event in angiosarcomas of the liver. The most common somatic alteration is promotor methylation of the p16 gene. We failed to establish p16 as independent prognostic factors in these tumors.

Genetic and molecular abnormalities in tumors of the bone and soft tissues

BACKGROUND

Malignant transformation requires the accumulation of multiple genetic alterations such as chromosomal abnormalities, oncogene activation, loss of tumor suppressor genes, or abnormalities in genes that control DNA repair and genomic instability. Sarcomas are a heterogeneous group of malignant mesenchymal tumors of difficult histologic classification and strong genetic predisposition. This article provides a comprehensive review of the cytogenetic abnormalities observed in bone and soft-tissue tumors, emphasizing known downstream molecular changes that may play a role in oncogenesis.

METHODS

The database of the National Library of Medicine was searched for literature relating to genetic and molecular mechanisms in sarcomas in general and in each of the main tumor entities.

RESULTS

Recent techniques in chromosome analysis and molecular cytogenetics have improved our ability to characterize genetic changes in mesenchymal tumors. Some changes are so characteristic as to be virtually pathognomonic of particular histologic types, while others are complex, difficult to characterize, and of unknown relevance to pathogenesis. The implications to the cell of some of these abnormalities are now being recognized.

CONCLUSIONS

The study of sarcomas will benefit from the information derived from genetic studies and translational research. The human genome project and new methodologies, such as computer-based DNA microarray, may help in the histogenetic classification of sarcomas and in the identification of molecular targets for therapy.

Isolation and characterisation of a novel human gene (C9orf11) on chromosome 9p21, a region frequently deleted in human cancer

The chromosome 9p21 region has been described to be frequently deleted in several neoplasias. The cyclin dependent kinase inhibitor 2A (CDKN2A or P16) gene was cloned in this region and identified as a tumour suppressor gene. However, much evidence indicates the existence of another tumour suppressor gene located proximal to the CDKN2A gene, which could be involved in cutaneous malignant melanoma (CMM) initiation. In the present report we have further investigated this 9p21 chromosomal region and cloned and characterised a novel gene within it (C9orf11). This gene shares no similarities to any known gene or predicted protein representing a novel human gene. Nevertheless, a putative leucine zipper pattern is located at the C-terminal end of the predicted protein, suggesting that it could dimerise. C9orf11 encodes for a protein of 294 amino acids with a predicted molecular mass of 32.8 kDa. C9orf11 is organised in eight exons that encompass a region of approx. 13 kb. Expression analysis demonstrates that C9orf11 is highly expressed in testis, although minor expression was seen in other tissues. Mutations in the C9orf11 gene were not detected in CMM families that were negative for CDKN2A mutations. Two SNPs for the C9orf11 gene have been identified, which could be used in segregation or association studies for other disorders.

Inclusion of malignant fibrous histiocytoma in the tumour spectrum associated with hereditary non-polyposis colorectal cancer

Sarcomas, including the malignant fibrous histiocytomas (MFHs), are not known to be part of the tumour spectrum of hereditary non-polyposis colorectal cancer (HNPCC) as epidemiologically established. Therefore, occurrence of MFH in an HNPCC family may very well be coincidental. HNPCC is associated with germline mutations in DNA mismatch repair genes, including the MSH2 gene. We analysed an MFH diagnosed in a 45-year-old male HNPCC patient carrying a germline MSH2 mutation for HNPCC-associated molecular characteristics, to investigate a possible relationship between the tumour and that mutation. DNA analysis revealed microsatellite instability and loss of one MSH2 copy, and immunohistochemistry showed absence of nuclear MSH2 protein staining. To investigate whether this is a common finding in MFH, microsatellite instability and nuclear MSH2 protein staining was tested for in 5 and 6 sporadic MFHs, respectively. None showed microsatellite instability and all stained positively for MSH2. Together, these findings show that in rare cases, MFH may be part of the HNPCC tumour spectrum.