Neurofibromatosis type 1-related gastrointestinal stromal tumors: a special reference to loss of heterozygosity at 14q and 22q.

Purpose: Multiple gastrointestinal stromal tumors (GISTs) rarely occur in patients with neurofibromatosis type 1 (NF-1). In contrast to sporadic GISTs characterized by frequent allelic losses of 1p, 14q and 22q and mutations of KIT or PDGFRA gene with the activation of the downstream RAS-MAPK pathway, the molecular pathogenetic mechanisms of NF-1-related GISTs (NF-1 GISTs) remain unclear.

Methods: Thirty-one GISTs and two foci of Cajal cell hyperplasia (CCH) were obtained from five patients with NF-1.

Endometrial stromal sarcomas and related high-grade sarcomas: immunohistochemical and molecular genetic study of 31 cases.

Classification and terminology of non-low-grade endometrial sarcomas, which show significant nuclear atypia, have been controversial. Currently, these tumors seem to be classified all together into "undifferentiated endometrial sarcoma (UES)." However, it remains unclear whether these non-low-grade sarcomas are universally "undifferentiated.

Alterations of RB1 gene in embryonal and alveolar rhabdomyosarcoma: special reference to utility of pRB immunoreactivity in differential diagnosis of rhabdomyosarcoma subtype.

Purpose: Rhabdomyosarcoma (RMS), which is the most common pediatric soft tissue sarcoma, is classified into two major histologic subtypes, embryonal RMS (ERMS) and alveolar RMS (ARMS). RMS is occasionally reported to be the second neoplasm of hereditary retinoblastoma. Osteosarcoma is known as the most common second neoplasm of hereditary retinoblastoma, and tumorigenesis of osteosarcoma has been proven in previous studies to be related to the RB gene (RB1) alteration.

Diffuse-type giant cell tumor/pigmented villonodular synovitis arising in the sacrum: malignant form.

Diffuse-type giant cell tumor (GCT)/pigmented villonodular synovitis (PVNS) in the axial skeleton or spine is rare. Herein is reported a case of diffuse-type GCT/PVNS involving the sacrum and the fifth lumbar vertebra, in which the patient developed regional lymph node swelling after recurrence. The recurrent tumor was found to have atypical histological features such as spindle cell morphology, cytological atypia and high mitotic rate, which are compatible with the diagnostic criteria of secondary malignant diffuse-type GCT/PVNS.

Detection of COL1A1-PDGFB fusion transcripts and PDGFB/PDGFRB mRNA expression in dermatofibrosarcoma protuberans.

Fusion of the collagen type I alpha 1 (COL1A1) gene with the platelet-derived growth factor beta chain (PDGFB) gene has been described in dermatofibrosarcoma protuberans. The abnormal fusion transcripts probably cause PDGFB and its receptor (platelet-derived growth factor receptor beta, PDGFRB) autocrine stimulation and cell proliferation, which are responsible for the development of dermatofibrosarcoma protuberans. A reverse transcription-polymerase chain reaction assay was performed to detect the COL1A1-PDGFB fusion transcripts in 57 samples.

Dysadherin expression as a significant prognostic factor and as a determinant of histologic features in synovial sarcoma: special reference to its inverse relationship with E-cadherin expression.

Dysadherin is a cancer-associated cell membrane glycoprotein, which down-regulates E-cadherin and promotes metastasis. Synovial sarcoma is a very rare mesenchymal tumor that exhibits an epithelial profile. To confirm the diagnosis of synovial sarcoma, we evaluated several immunohistochemical markers, or detected SYT-SSX fusion gene transcript.

Prognostic significance of dysadherin expression in epithelioid sarcoma and its diagnostic utility in distinguishing epithelioid sarcoma from malignant rhabdoid tumor.

Dysadherin is a cancer-associated cell membrane glycoprotein, which downregulates E-cadherin and promotes metastasis. We studied the clinicopathological features in 72 cases of epithelioid sarcoma and in six cases of malignant rhabdoid tumor, and also assessed the immunohistochemical expression of dysadherin, E-cadherin and MIB-1 in epithelioid sarcoma and malignant rhabdoid tumor cases. In addition, we compared dysadherin mRNA expression between epithelioid sarcoma and malignant rhabdoid tumor cell lines, using RT-PCR and real-time quantitative RT-PCR analysis.

Aberrant expression of CHFR in malignant peripheral nerve sheath tumors.

Mitotic checkpoint maintains genomic integrity before mitosis. Numerous observations have suggested that mitotic abnormalities produce chromosomal instability and aneuploidy. In MPNST, complex karyotypes showing numerical and structural aberrations have been described.

Chromosomal aberrations and microsatellite instability of malignant peripheral nerve sheath tumors: a study of 10 tumors from nine patients.

Malignant peripheral nerve sheath tumor (MPNST) is an uncommon soft tissue neoplasm with a poor prognosis, occurring sporadically or associated with neurofibromatosis type 1 (NF1); however, the histogenesis of MPNST remains unclear, especially in sporadic tumors. There are two major forms of genomic instability in human cancer: chromosomal instability (CIN) and microsatellite instability (MSI). An inverse relationship has recently been demonstrated between CIN and MSI in colorectal cancers.

DNA hypermethylation status of multiple genes in soft tissue sarcomas.

The aberrant methylation of promoter CpG islands is known to be a major inactivation mechanism of tumor-related genes. To determine the clinicopathological significance of gene promoter methylation in soft tissue sarcomas, we examined the promoter methylation status of 10 tumor-related genes in 65 soft tissue sarcomas and 19 adjacent non-neoplastic tissues by methylation-specific PCR. The methylation frequencies of tumor-related genes tested in soft tissue sarcomas were 17 (26%) for RASSF1A, 11 (17%) for DAP kinase, 10 (15%) for MGMT, nine (14%) for GSTP1, eight (12%) for PTEN, six (9%) for p16 and hMLH1, five (8%) for hMSH2, two (3%) for p14, and one (2%) for RB.

Frequent alteration of p16(INK4a)/p14(ARF) and p53 pathways in the round cell component of myxoid/round cell liposarcoma: p53 gene alterations and reduced p14(ARF) expression both correlate with poor prognosis.

In myxoid/round cell liposarcoma (MLS/RCLS), the presence of a round cell (RC) component has been reported to correlate with a worse prognosis for the patients. However, little is known about the molecular genetic differences between conventional myxoid (MX) components and RC components in this tumour. The aim of this study was to investigate the possible implications of molecular alterations of G1 to S-phase check-point genes, especially in the RC component.

Alterations of the RB1 gene in dedifferentiated liposarcoma.

Dedifferentiated liposarcoma is a malignant adipocytic neoplasm containing a non-lipogenic sarcoma of variable histological grade that arises against the background of a pre-existing well-differentiated liposarcoma. The phenomenon of dedifferentiation is considered to be time-dependent, but the mechanism is not well known. The retinoblastoma protein, encoded by the RB1 gene located at 13q14, is a key regulator of proliferation, development, and differentiation of certain cell types, including adipocytes.

Genetic and epigenetic alterations of the PTEN gene in soft tissue sarcomas.

The PTEN/MMAC1 ( PTEN ) gene was identified as a tumor suppressor gene encoding a cytoplasmic protein that controls cellular processes. To investigate the potential role and the alteration of the PTEN gene in soft tissue sarcomas (STSs), we searched for homozygous deletion and promoter hypermethylation in a series of 48 STSs that was composed of malignant fibrous histiocytoma, leiomyosarcoma, malignant peripheral nerve sheath tumor, including 2 cases with a mutation that we previously reported; differential polymerase chain reaction and methylation-specific polymerase chain reaction, respectively, were used for the analyses. Furthermore, to determine whether PTEN gene alterations are involved in the down-regulation of PTEN expression, we examined the expression of PTEN protein in 38 cases in which paraffin-embedded tissues were available for immunohistochemical analysis.

Microsatellite instability and hMLH1 and hMSH2 expression analysis in soft tissue sarcomas.

Alterations of the size of microsatellite DNA sequences, namely microsatellite instability (MSI), have been demonstrated in some types of malignancies. We analyzed the MSI of five microsatellite markers in 40 cases of soft tissue sarcoma (STS) using high resolution fluorescent microsatellite analysis. In addition, we examined the expression of hMLH1 and hMSH2 proteins of DNA mismatch repair (MMR) genes by immunohistochemistry, and promoter methylation of the hMLH1 gene by methylation-specific PCR (MSP).

Death-associated protein kinase (DAP kinase) alteration in soft tissue leiomyosarcoma: Promoter methylation or homozygous deletion is associated with a loss of DAP kinase expression.

The death-associated protein kinase (DAP kinase) was initially identified as a positive mediator of programmed cell death induced by interferon-gamma. To investigate the potential role and the alteration of the DAP kinase gene in soft tissue leiomyosarcoma (LMS), we first searched for homozygous deletion and promoter hypermethylation in 45 LMSs for which genomic DNA was available, using differential PCR and methylation-specific PCR, respectively. Promoter methylation was recognized in 10 of 45 cases (22%), and homozygous deletion was detected in 3 of 45 cases (7%).

Alterations of the p16INK4a/p14ARF pathway in clear cell sarcoma.

Clear cell sarcoma (CCS) is a very rare soft tissue sarcoma with a poor prognosis. It has become apparent through immunohistochemical, ultrastructural, and microarray analyses that CCS is a soft tissue melanocytic neoplasm. Alterations in the p16INK4a/p14ARF gene are common in malignant melanoma, which is the prototypical melanocytic neoplasm.

c-kit and PDGFRA mutations in extragastrointestinal stromal tumor (gastrointestinal stromal tumor of the soft tissue).

Extragastrointestinal stromal tumor (EGIST) is a unique tumor that occurs outside the gastrointestinal tract. EGIST shows a c-kit expression and histologic appearance similar to those of gastrointestinal stromal tumor (GIST). Most GISTs have gain-of-functional mutation of the c-kit gene, and some have mutation of the platelet-derived growth factor receptor-alpha (PDGFRA) gene.

PTEN and other tumor suppressor gene mutations as secondary genetic alterations in synovial sarcoma.

Synovial sarcomas (SS) consistently show a characteristic chromosomal translocation, t(X;18)(p11;q11), which usually leads to the formation of 2 chimeric fusion transcripts, SYT-SSX1 and -SSX2. A recent multi-institutional retrospective study revealed that the SYT-SSX fusion type emerged as the only independent significant factor for overall survival in cases of SS. The aims of this study were; i).

Microsatellite instability and p53 mutation associated with tumor progression in dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is a dermal and subcutaneous tumor categorized as a tumor of intermediate malignancy, and its progression in some cases to fibrosarcoma is well known. However, molecular analysis of tumor progression has been limited. The present study investigated microsatellite instability (MSI) of 7 microsatellite markers through high-resolution microsatellite analysis in addition to a mutational analysis of the p53 gene in 44 tumors in 36 patients.

Decreased expression of transforming growth factor-beta II receptor is associated with that of p27KIP1 in giant cell tumor of bone: a possible link between transforming growth factor-beta and cell cycle-related protein.

Transforming growth factor (TGF)-beta is a potential regulator of cell growth that sends its signals through a heteromeric complex composed of type I and II receptors (IR and IIR). This study examined a correlation between TGF-beta1, TGF-beta-IR and -IIR, and cell cycle-related proteins in giant cell tumor (GCT) of bone, using immunohistochemical and Western blot analysis. First, an immunohistochemical study for TGF-beta1, TGF-beta-IR and -IIR, p27KIP1 (p27), p21WAF1 (p21), cyclin D1, and cyclin E was carried out on 92 cases of GCT of bone; the expression of these proteins was evaluated in multinucleated giant cells (MGCs) and mononucleated stromal cells (MSCs) separately; and proliferative activity was assessed using MIB-1.

Altered expression of cell cycle regulators in myxofibrosarcoma, with special emphasis on their prognostic implications.

Myxofibrosarcoma/myxoid malignant fibrous histiocytoma (MFH) has continued to be considered a distinct entity even after recently published reassessments of pleomorphic sarcomas and MFH. Several cell cycle-regulated proteins have already been screened by immunohistochemistry with the aim of finding the reliable prognostic indicator of soft tissue sarcomas; however, it is still unknown whether their altered expression affects patient survival in myxofibrosarcoma. In this study, we evaluated the expression of p53, MDM2, MIB-1 (Ki-67), p21, p27, p16, cyclin A, cyclin D1, and cyclin E by immunohistochemistry in 45 cases of myxofibrosarcoma.

Mechanisms of inactivation of the p16INK4a gene in leiomyosarcoma of soft tissue: decreased p16 expression correlates with promoter methylation and poor prognosis.

The p16INK4a tumour suppressor gene, encoding p16 protein, plays a crucial role in regulation of the G1 cell-cycle phase. To investigate the potential role of p16 in soft tissue leiomyosarcoma (LMS), an immunohistochemical analysis was performed of 77 LMSs for p16 expression. Decreased expression of the p16 protein was identified in 25 of 77 LMSs (32%).

Possible association between tumor-suppressor gene mutations and hMSH2/hMLH1 inactivation in alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor of unknown origin and pathogenesis. We clinicopathologically analyzed 16 cases of ASPS and screened for the genetic alterations of various tumor-suppressor genes and oncogenes, including p53, adenomatous polyposis coli (APC), E-cadherin, and beta-catenin, in 11 cases of ASPS. We also examined the expression of hMSH2/hMLH1 of DNA mismatch repair genes by immunohistochemistry, and promoter hypermethylation of these DNA mismatch repair genes by methylation-specific polymerase chain reaction (MS-PCR) to elucidate any possible association between mutation status of these genes and inactivation of the hMSH2/hMLH1 genes.

PTEN/MMAC1 gene mutation is a rare event in soft tissue sarcomas without specific balanced translocations.

The tumor suppressor gene PTEN/MMAC1 was identified on chromosome 10q23.3, which is homozygously deleted in many human malignancies. The loss of chromosome 10q was also frequently reported in some types of soft tissue sarcomas.