ras gene mutations in salivary gland tumors

OBJECTIVE: To assess the prevalence of activating mutations in K-ras and H-ras genes in salivary gland tumors with ductal or acinar differentiation and to evaluate their potential correlation with clinical parameters. DESIGN: Paraffin-embedded tissue samples of salivary gland carcinomas were investigated by the application of a direct sequence analysis procedure with automated DNA sequencing of polymerase chain reaction-amplified ras sequences. SETTING: Tertiary care teaching hospital. PATIENTS: Twenty-four patients with salivary gland carcinoma were surgically treated. Nine had adenocarcinoma, 1 had adenosquamous carcinoma, 11 had mucoepidermoid carcinoma, and 3 had acinic cell carcinoma. RESULTS: Point mutations were detected in 7 (29%) of the 24 carcinomas examined. The K-ras gene was mutated in only 2 samples (8%): a GGC-to-ATC mutation at codon 13 in an adenocarcinoma and a GGC-to-GTC transversion mutation at codon 13 in a mucoepidermoid carcinoma. Five (21%) harbored H-ras mutations: 4 contained a GGC-to-GTC transversion mutation at codon 12 and 1 had 2 distinct mutations, the same G-to-T at codon 12 as was shown in the other cases and a GGT-to-GGA heterozygous mutation at codon 13. All the H-ras mutations were in the group of mucoepidermoid carcinoma lesions (45%; 5/11). CONCLUSION: Our data suggest that K-ras gene alteration is probably not an important factor in the oncogenesis of human salivary gland tumors. However, mutational activation of the H-ras gene appears to play a role in the development and/or progression of salivary gland mucoepidermoid carcinomas.     

H-, K-, and N-ras gene mutation in atypical fibroxanthoma and malignant fibrous histiocytoma.

Atypical fibroxanthoma (AFX) which is histologically similar to malignant fibrous histiocytoma (MFH), occurs in the sun-exposed skin. The presence of mutations at codons 12 and 13 of the H- and K-ras genes and in exons 1 and 2, which include codons 12, 13, and 61, of the N-ras gene was studied in 8 cases of AFX and 8 cases of storiform-pleomorphic-type MFH using polymerase chain reaction (PCR)-restriction fragment length polymorphism and PCR-single-conformation polymorphism. Two of the 8 cases of MFH showed ras mutations in the H-ras gene at codon 12 (GGC-AGC) and in the K-ras gene at codon 13 (GGC-GAC). H- and K-ras gene mutations were not seen in any of the cases of AFX (0 of 8). N-ras gene mutation was not detected in either the AFX (0 of 8) or MFH (0 of 8) cases. In conclusion, although the number of cases in this study was small, H- and K-ras genes were present in some of the MFH cases and accordingly may play an important role in the pathogenesis of MFH. In addition, the finding that H-, K-, and N-ras gene mutations are not present in AFX may indicate why AFX has a more favorable behavior than MFH.     

Mutational activation of the K-ras oncogene. A possible pathogenetic factor in adenocarcinoma of the lung

To define the role of cellular oncogenes in human cancers, we studied the prevalence of mutational activation of ras oncogenes in untreated non-small-cell lung cancer. Genomic DNA was extracted from 39 tumor specimens obtained by thoracotomy and was examined for activating point mutations in codons 12, 13, and 61 of the H-ras, K-ras, and N-ras genes. A novel, highly sensitive assay based on oligonucleotide hybridization following an in vitro amplification step was employed. The K-ras gene was found to be activated by point mutations in codon 12 in 5 of 10 adenocarcinomas. Two of these tumors were less than 2 cm in size and had not metastasized. No ras gene mutations were observed in 15 squamous-cell carcinomas, 10 large-cell carcinomas, 1 carcinoid, 2 metastatic adenocarcinomas from primary tumors outside the lung, and 1 small-cell carcinoma. An approximately 20-fold amplification of the unmutated K-ras gene was observed in a tumor that proved to be a solitary lung metastasis of a rectal carcinoma. We conclude that mutational K-ras activation may be an important early event in the pathogenesis of adenocarcinoma of the lung but that amplification of ras genes or mutational activation of H-ras or N-ras does not play a major part in non-small-cell lung cancer.     

H-ras oncogene mutation in dedifferentiated liposarcoma. Polymerase chain reaction-restriction fragment length polymorphism analysis

Point mutations of the ras gene family (K-ras, H-ras, and N-ras) are thought to be involved in the development of a variety of human tumors. Dedifferentiated liposarcoma is characterized by the coexistence of well-differentiated (WD) and high-grade anaplastic (HG) components. The presence of point mutations at codons 12 and 13 of the H-ras gene was studied in 34 liposarcomas, comprising 15 well-differentiated liposarcomas and 19 dedifferentiated liposarcomas, and in 8 storiform-pleomorphic type malignant fibrous histiocytomas (MFHs) using polymerase chain reaction-restriction fragment length polymorphism and direct sequencing analysis. The 2 components of dedifferentiated liposarcoma were analyzed independently. H-ras mutations were seen only in dedifferentiated liposarcomas (4/19 [21%]), 1 in WD components and 3 in HG components. The mutation was not seen in any of 15 cases of well-differentiated liposarcoma. MFHs showed an H-ras mutation in 1 (12%) of 8 cases. Our results seem to suggest that the H-ras mutation is a relatively uncommon event in dedifferentiated liposarcoma, which may demonstrate an epiphenomenon of dedifferentiation in dedifferentiated liposarcoma.     

Gene expression analysis of soft tissue sarcomas: characterization and reclassification of malignant fibrous histiocytoma.

In soft tissue sarcomas, the diagnosis of malignant fibrous histiocytoma (MFH) has been a very controversial issue, and MFH is now considered to be reclassified into pleomorphic subtypes of other sarcomas. To characterize MFH genetically, we used an oligonucleotide microarray to analyze gene expression in 105 samples from 10 types of soft tissue tumors. Spindle cell and pleomorphic sarcomas, such as dedifferentiated liposarcoma, myxofibrosarcoma, leiomyosarcoma, malignant peripheral nerve sheath tumor (MPNST), fibrosarcoma and MFH, showed similar gene expression patterns compared to other tumors. Samples from those five sarcoma types could be classified into respective clusters based on gene expression by excluding MFH samples. We calculated distances between MFH samples and other five sarcoma types (dedifferentiated liposarcoma, myxofibrosarcoma, leiomyosarcoma, MPNST and fibrosarcoma) based on differentially expressed genes and evaluated similarities. Three of the 21 MFH samples showed marked similarities to one of the five sarcoma types, which were supported by histological findings. Although most of the remaining 18 MFH samples showed little or no histological resemblance to one of the five sarcoma types, 12 of them showed moderate similarities in terms of gene expression. These results explain the heterogeneity of MFH and show that the majority of MFHs could be reclassified into pleomorphic subtypes of other sarcomas. Taken together, gene expression profiling could be a useful tool to unveil the difference in the underlying molecular backgrounds, which leads to a rational taxonomy and diagnosis of a diverse group of soft tissue sarcomas.     

Polymerase chain reaction/sequencing analysis of ras mutations in paraffin-embedded tissues as compared with 3T3 transfection and polymerase chain reaction/sequencing of frozen tumor deoxyribonucleic acids.

The efficiency of detection of H- and K-ras mutations in 27 CD-1 mouse liver tumors by direct sequencing of polymerase chain reaction (PCR)-amplified DNA isolated from formalin-fixed and paraffin-embedded tissues was compared with that after assay by both NIH 3T3 transfection (followed by sequencing of amplified transformant DNA) and direct sequencing of PCR-amplified DNA isolated from frozen tumors. Some tumor samples were chosen for comparison because they contained ras mutations that were detected by either NIH 3T3 transfection or sequencing of PCR-amplified DNA derived from frozen tumors, but were not detected by both techniques. The efficiency of detecting K-ras mutations was similar for sequencing of amplified fragments derived from both paraffin-embedded tissues and from frozen tumors. However, these two techniques differed in their efficacy for detection of H-ras codon 61 mutations. Furthermore, this difference appeared to be mutation-specific: the sequencing of amplified products from paraffin-embedded tumor tissues allowed increased detection of CAA to AAA mutations but decreased detection of CAA to CTA mutations relative to sequencing of amplified fragments derived from frozen tumor DNA. Direct sequencing of PCR products from paraffin-embedded sections was more sensitive than NIH 3T3 transfection for detection of activated K-ras genes containing codon 13 mutations but less sensitive for detection of activated H-ras genes containing codon 61 mutations. In summary, direct sequencing of amplified DNA from either frozen tumors or formalin-fixed, paraffin-embedded tissues can be more sensitive than NIH 3T3 transfection for detection of codon 13-activated K-ras genes. However, it appears to be less sensitive than NIH 3T3 transfection for detection of certain activating H-ras mutations. Depending upon the questions being asked of the data, each of the methods can provide useful information about ras gene mutations in tumor samples. The apparent differences in sensitivities between the methods is not yet understood, but such differences should be considered in the analysis of data obtained when only one method is used.     

High frequency of ras mutations in forestomach and lung tumors of B6C3F1 mice exposed to 1-amino-2,4-dibromoanthraquinone for 2 years

1-Amino-2,4-dibromoanthraquinone (ADBAQ) is an anthraquinone-derived vat dye, and a potent carcinogen in laboratory animals. In a 2-year study with dietary exposure to 10,000 or 20,000 ppm ADBAQ, increased incidence of forestomach and lung tumors were observed in B6C3F1 mice. The present study indentified genetic alterations in H-ras and K-ras proto-oncogenes in ADBAQ-induced tumors. Point mutations in ras proto-oncogenes were identified by restriction fragment length polymorphism, single-stranded conformational polymorphism analysis and cycle sequencing of polymerase chain reaction-amplified DNA isolated from paraffin-embedded squamous cell papillomas and carcinomas in the forestomach, and alveolar/bronchiolar adenomas and carcinomas in the lung. A higher frequency of ras mutations was identified in ADBAQ-induced forestomach (23/32, 72%) and lung tumors (16/23, 70%) than in spontaneous forestomach (4/11, 36%) and lung tumors (26/86, 30%). H-ras codon 61 CTA mutations were detected in (4/8, 50%) ADBAQ-induced forestomach squamous cell papillomas and (10/24, 42%) squamous cell carcinomas, but not in the spontaneous forestomach tumors examined. H-ras codon 61 CGA mutation (6/24, 25%) was also detected in ADBAQ-induced forestomach squamous cell carcinomas. K-ras codon 61 A to T transversions and A to G transitions were prominent in ADBAQ-induced lung alveolar/bronchiolar adenomas and alveolar/bronchiolar carcinomas. The major finding of A to T transversions or A to G transitions in forestomach and lung tumors suggests that ADBAQ or its metabolites target adenine bases in the ras proto-oncogenes and that these mutations play a dominant role in multi-organ     

High-degree tumor budding and podia-formation in sporadic colorectal carcinomas with K-ras gene mutations

In vitro ras activation enhances the epithelial-mesenchymal transition of colorectal carcinoma cells. But ras effects are known to be highly dependent on cell types and the tissue context. Therefore, this study was made to test the hypothesis that in clinical colorectal carcinoma specimens, aggressive invasion phenotypes, specifically tumor budding and podia formation, would correlate with K-ras gene mutations. In a series of 95 clinically sporadic primary colorectal carcinomas collected ad hoc, tumor budding and podia formation were counted using pan-cytokeratin immunohistochemistry, and K-ras gene mutations in codons 12 and 13 were determined. Consistent with the hypothesis, tumor budding and podia formation were observed to be significantly higher in the 32 (34.7%) of the tumors with K-ras gene mutations (29 mutations in codon 12, 3 in codon 13), and this correlation was observed independent of the patterns of invasion (expansive versus infiltrative). Microsatellite status, numbers of losses of heterozygosity, adenomatous polyposis coli and p53 gene mutations, and degree of promoter methylations (CIMP status) were not associated with K-ras gene mutations. Besides their effects on the tumor cell cycles, oncogenic K-ras gene mutations in colorectal carcinomas could be important for aggressive tumor invasion. This may be important in metastasizing disease and could provide a rationale for developing drugs that interrupt ras-signaling cascades.     

Mutations of ras protooncogenes and p53 tumor suppressor gene in cardiac hemangiosarcomas from B6C3F1 mice exposed to 1,3-butadiene for 2 years

1,3-Butadiene is a multisite carcinogen in rodents. Incidences of cardiac hemangiosarcomas were significantly increased in male and female B6C3F1 mice that inhaled 1,3-butadiene (BD) for 2 years. Eleven BD-induced cardiac hemangiosarcomas were examined for genetic alterations in ras protooncogenes and in the p53 tumor suppressor gene. Nine of 11 (82%) BD-induced hemangiosarcomas had K-ras mutations and 5 of 11 (46%) had H-ras mutations. All of the K-ras mutations were G-->C transversions (GGC-->CGC) at codon 13; this pattern is consistent with reported results in BD-induced lung neoplasms and lymphomas. Both K-ras codon 13 CGC mutations and H-ras codon 61 CGA mutations were detected in 5 of 9 (56%) hemangiosarcomas. The 11 hemangiosarcomas stained positive for p53 protein by immunohistochemistry and were analyzed for p53 mutations using cycle sequencing of polymerase chain reaction (PCR) amplified DNA isolated from paraffin-embedded sections. Mutations in exons 5 to 8 of the p53 gene were identified in 5 of 11 (46%) hemangiosarcomas, and all of these were from the 200- or 625-ppm exposure groups that also had K-ras codon 13 CGC mutations. Our data indicate that K-ras, H-ras, and p53 mutations in these hemangiosarcomas most likely occurred as a result of the genotoxic effects of BD and that these mutations may play a role in the pathogenesis of BD-induced cardiac hemangiosarcomas in the B6C3F1 mouse.     

Ras gene activation in malignant cells of human ovarian carcinoma peritoneal fluids

In this study, we showed, for the first time, the pattern of point mutations at codon 12 of the K-ras, H-ras and N-ras genes, using polymerase chain reaction and restriction fragment length polymorphism analysis in 47 malignant cytologic specimens of ovarian adenocarcinoma peritoneal fluids. Forty-seven % of the samples were found to carry a point mutation at codon 12 of K-ras gene. Also, 21 cystadenoma peritoneal fluids were used as control specimens for the detection of ras mutations. Fourteen % of these samples were found to carry a point mutation at codon 12 of the K-ras gene. The prevalence of K-ras gene mutations were statistically correlated with FIGO and surgical stage of the malignant specimens. Our data demonstrates that the K-ras gene mutations are mainly affected (47%) in the malignant cells of the peritoneal washings or ascites of women with ovarian adenocarcinomas and may have value for the early diagnosis and monitoring of these neoplasms.     

Characterization of human soft tissue sarcomas in nude mice. Evidence for histogenic properties of malignant fibrous histiocytomas.

Twenty-two human sarcomas were grafted subcutaneously into nude mice. Twelve tumors grew successfully. Nine of these 12 tumors had an aneuploid DNA content, whereas only 1 of 10 nonsuccessful tumors was aneuploid. The 12 sarcomas included two leiomyosarcomas, two malignant schwannomas, one synovial sarcoma, and seven malignant fibrous histiocytomas (MFHs). With light and electron microscopic and immunolabeling studies the original and xenografted tumors (the latter for at least two generations) were histopathologically compared. The xenografted leiomyosarcomas showed ultrastructurally a more pronounced leiomyodifferentiation, and one of the malignant schwannomas a more pronounced schwannian differentiation. The second malignant schwannoma and the synovial sarcoma, however, remained unchanged. Five storiform pleomorphic MFHs expressed features that were not observed in the original tumors. Tumor cells of three of these xenografted sarcomas showed leiomyogenic differentiation (filamentous densities, pinocytotic vescicles, and desmin immunoreactivity), whereas cells of the two others demonstrated schwannian differentiation (long cytoplasmic processes, basal lamina). A xenografted myxoid MFH and a pleomorphic MFH gave rise to pleomorphic sarcomas composed of undifferentiated cells. It appeared that under transplantation conditions tumor cells of storiform pleomorphic MFH can differentiate into various directions.     

ras Gene mutations and expression of Ras signal transduction mediators in gastric adenocarcinomas

OBJECTIVE: To investigate ras gene alteration in human gastric adenocarcinomas and its potential relationship to ras signal transduction mediators. DESIGN: Genomic DNA from 104 gastric tumors were analyzed by sequencing of polymerase chain reaction-amplified products for the presence of ras mutations. All the samples were further investigated with the use of immunohistochemical analysis for ERK1 and ERK2. SETTING: Tertiary care teaching hospital. PATIENTS: Seventy patients from a Korean population and 34 from a Midwestern US population composed of white Americans and African Americans. RESULTS: Fifteen tumors (14%) were positive for either H-ras or K-ras mutation: 9 (13%) of 70 Korean patients and 6 (18%) of 34 US patients. Seven (78%) of the 9 mutated tumors from Korean patients and all 6 (100%) from the US patients were intestinal-type lesions. Either ERK1 and/or ERK2 was overexpressed in 68 samples (65%). No association was established between ras mutations and overexpression of ERK1/2. However, the correlation between ERK1/2 and progression (early vs late) was statistically significant (P =.007). CONCLUSIONS: These data suggest that ras mutations are uncommon in gastric adenocarcinomas and that differing racial and/or geographic mechanisms may not underlie ras gene alteration. Most ras mutations were, however, observed in the group of intestinal-type samples, supporting the different genetic mechanisms of carcinogenesis between the intestinal- and diffuse-type tumors. It is noteworthy that enhanced ERK1/2 activity could be one of the characteristics of tumor invasiveness in gastric cancers.     

The role of p21ras in pancreatic neoplasia and chronic pancreatitis.

K-ras mutations have been detected in both ductal cell carcinoma and intraductal papillary mucinous tumor (IPMT) of pancreas. The frequency of this mutation in ductal cell carcinoma is high, whereas in IPMT, it is variable. It has been suggested that the relatively high frequency of this mutation in ductal cell carcinomas compared with IPMT may account for the differences in biological behavior between these tumor types. More recently, the significance of K-ras mutations in pancreatic tissue has been questioned with the demonstration of this mutation in nonneoplastic pancreata. The current study aims to estimate the relative frequency and evaluate the biological significance of K-ras gene mutations in these neoplasms by performing polymerase chain reaction (PCR) assays of microdissected areas of IPMT, ductal cell carcinomas, and resected chronic pancreatitis. The study also investigates whether alterations of p21ras occur in K-ras mutation-negative cases by using immunohistochemical staining for K-, N- and H-ras. K-ras codon 12 mutations were found almost as frequently in IPMT (71%) as in ductal cell carcinomas (78%). They were also associated with the earliest morphological lesion, flat mucinous change. This mutation also was detected in 42% of cases of chronic pancreatitis. Expression of p21ras was found to correlate closely with K-ras mutation status in IPMT and ductal cell carcinoma. Negative staining for pan-ras, H-ras, and N-ras in cases with wild-type K-ras genes suggests that alternative routes of ras gene alteration are not operative in IPMT or ductal carcinoma. The findings suggest that K-ras activation is frequently associated with both IPMT and ductal cell carcinoma. Its high prevalence in nonneoplastic pancreata suggests that it is also associated with self-limited morphological lesions of the pancreas that do not progress to malignancy.     

Myxoid malignant fibrous histiocytoma and pleomorphic liposarcoma share very similar genomic imbalances

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma. Nevertheless, the validity of this heterogeneous pathological entity has been recurrently questioned by pathologists. Recently, analyses by comparative genomic hybridization (CGH) of a large series of MFHs suggested that MFHs consist of morphologic modulation of other poorly differentiated sarcomas like leiomyosarcomas (LMS) or dedifferentiated liposarcomas (DLPS). We report here an analysis by CGH of 22 myxoid MFHs (mMFH), one of the five histological subtypes of MFH, and of nine pleomorphic liposarcomas (pLPS), a rare poorly differentiated LPS. The chromosome imbalances encountered in the series of mMFH were very similar to those observed in the series of pLPS studied in the laboratory and in the series of 14 pLPS published in the literature. The most frequent gains involved chromosome subregions: pericentromeric regions of 1, 5p, 19p, 19q and 20q. Losses found in the chromosomal arms 1q, 2q, 3p, 4q, 10q, 11q and 13q were also recurrent. The use of a clustering software did not separate the two pathological groups (mMFH and pLPS) on the basis of genomic data. Moreover, pLPS-mMFH represented, according to the clustering software results, an entity clearly distinguished from other soft tissue sarcomas, LMS in particular, with which they share common genetic aberrations. Additional studies are needed to identify genes targeted by these genomic aberrations, and implicated in the oncogenesis of these tumor subtypes. The characterization of common gene alterations in both tumor groups would suggest a closer relationship between these two types of soft tissue sarcomas.     

HLA molecules in basal cell carcinoma of the skin.

Fifty basal cell carcinomas (BCC) and 8 samples of healthy skin were studied for HLA class I and class II antigen expression and for the presence of mutations in codon 12 of the K-ras and H-ras genes. All samples of healthy skin and of epithelium near the tumor showed high levels of class I molecules, whereas 38% of the tumors showed complete absence. Sixty-two percent of the tumors presented positive class I expression with heterogeneous staining. These losses were due to the simultaneous lack of heavy chain and beta 2-microglobulin. Selective losses of HLA-A or HLA-B antigens were not detected. Class II antigens were absent in most of the tumors, only two tumors showing a few weakly positive cells with anti-HLA-DR mAb. The loss of class I expression correlated significantly with the degree of histological differentiation and aggressiveness. We were unable to correlate class I expression with clinical size, depth of invasion or the extent of leukocytic infiltrate surrounding the tumor. Analysis by PCR amplification of codon 12 of the K-ras and H-ras oncogenes detected H-ras mutations in 1 out of 50 cases, and no K-ras mutations in any of the tumors studied. Thus, a positive relationship between K-ras and H-ras mutations and BCC tumorigenesis or MHC alterations seems unlikely in this neoplasia.     

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.     

HLA-DR (Ia-like) reactivity in tumors of bone and soft tissue: an immunohistochemical comparison of monoclonal antibodies LN3 and LK8D3 in routinely processed specimens.

Recent studies of Class II histocompatibility antigen expression in bone and soft tissue sarcomas have suggested that malignant fibrous histiocytoma (MFH) may express HLA-DR, whereas histologically similar pleomorphic, epithelioid, and spindle cell malignant neoplasms generally do not. To test whether these observations are reproducible in the differential diagnosis of soft tissue sarcomas, anti-HLA-DR antibodies LK8D3 and LN3 were applied to formalin-fixed, paraffin-embedded sections of MFH, neurofibrosarcoma (NFS), leiomyosarcoma (LMS), synovial sarcoma (SS), fibrosarcoma (FS), angiosarcoma (AS), Kaposi's sarcoma (KS), chondrosarcoma (ChS), "dedifferentiated" chondrosarcoma (DChS), osteosarcoma (OS), epithelioid sarcoma (ES), and clear cell sarcoma (CCS; malignant melanoma of soft parts). The only consistent difference in Class II antigen expression was seen in the group of neoplasms composed of large polygonal cells. Among the latter lesions, four of six clear cell sarcomas were labeled by LK8D3 or LN3, but none of 12 epithelioid sarcomas were reactive. Otherwise, a diversity of tumors in other morphologic categories expressed Class II antigens, with no clear diagnostic patterns. These results may be of use in the diagnostic separation of large cell epithelioid tumors of soft tissue, but neither LN3 nor LK8D3 appears to be helpful in the identification of other sarcomas.     

亚硝基诱发大鼠胃腺癌发生发展过程中p53,ras基因表达和突?…

目的 探讨Ｐ５３、ｒａｓ基因在亚硝基胍诱发大鼠胃腺癌发生发展过程中的作用。方法 用免疫组织化学、聚合酶链反应－单链构象多态怀分析（ＰＣＲ－ＳＳＣＰ）技术对大鼠正常腺胃粘膜、癌前病变和胃腺癌组织中ｐ５３、ｒａｓ基因的表达和突变进行检测。结果Ｐ５３蛋白在癌组织 的了性表达率为５０％,正常和癌前病缲为阴性;ｒａｓ蛋白癌前病变组织中阳性率为４４％,在癌组织中为２３％。癌组织中ｐ５３基因突变率为４５％,非     

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.     

卵巢浆液性交界及恶性肿瘤K-ras基因突变分析

目的探讨K-ras基因在卵巢浆液性交界及恶性肿瘤发生发展过程中的作用。方法收集51例卵巢浆液性肿瘤标本,包括经典型交界性浆液性肿瘤18例,微乳头型交界性浆液性肿瘤11例,浸润性微乳头型浆液性癌12例,经典型浆液性癌10例。采用显微切割技术获取肿瘤细胞后,提取基因组DNA、PCR技术扩增K—ras基因第一外显子,通过直接测序的方法鉴定K—ras基因第12、13密码子的突变情况。结果1例经典型交界性浆液性肿瘤K—ras基因第12密码子发生突变,突变类型为GGT→GTT即甘氨酸→缬氨酸,余50例标本未见突变;所有标本K—ras基因第13密码子均为野生型。结论K—ras基因第12、13密码子在被检患者中卵巢浆液性交界及恶性肿瘤中的突变频率很低,其在该肿瘤发生发展过程中可能不起主要作用。