Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

Activity of sunitinib in extraskeletal myxoid chondrosarcoma

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma, marked by NR4A3 rearrangement. Herein we report on the activity of sunitinib in a series of 10 patients, strengthening what initially observed in two cases.

PATIENTS AND METHODS

From July 2011, 10 patients with progressive metastatic translocated EMC have been consecutively treated with sunitinib 37.5mg/day, on a named-use basis. In an attempt to interpret the activity of sunitinib in EMC, genotype/phenotype correlations were carried out by fluorescence in situ hybridization (FISH) analyses. Moreover, transcriptome, immunohistochemical and biochemical analyses of a limited set of samples were performed focusing on some putative targets of sunitinib.

RESULTS

Eight of 10 patients are still on therapy. Six patients had a Response Evaluation Criteria in Solid Tumours (RECIST) partial response (PR), two were stable, two progressed. Positron emission tomography (PET) was consistent in 6/6 evaluable cases. One patient underwent surgery after sunitinib, with evidence of a pathologic response. At a median follow-up of 8.5 months (range 2-28), no secondary resistance was detected. Median progression free survival (PFS) has not been reached. Interestingly, all responsive cases turned out to express the typical EWSR1-NR4A3 fusion, while refractory cases carried the alternative TAF15-NR4A3 fusion. Among putative sunitinib targets, only RET was expressed and activated in analysed samples.

CONCLUSIONS

This report confirms the therapeutic activity of sunitinib in EMC. Genotype/phenotype analyses support a correlation between response and EWSR1-NR4A3 fusion. Involvement of RET deserves further investigation.

Morphology, mineralogy, and solid-liquid phase separation characteristics of Cu and Zn precipitates produced with biogenic sulfide

The morphology, mineralogy, and solid-liquid phase separation of the Cu and Zn precipitates formed with sulfide produced in a sulfate-reducing bioreactor were studied at pH 3, 5, and 7. The precipitates formed at pH 7 display faster settling rates, better dewaterability, and higher concentrations of settleable solids as compared to the precipitates formed at pH 3 and 5. These differences were linked to the agglomeration of the sulfidic precipitates and coprecipitation of the phosphate added to the bioreactor influent. The Cu and Zn quenched the intensity of the dissolved organic matter peaks identified by fluorescence-excitation emission matrix spectroscopy, suggesting a binding mechanism that decreases supersaturation, especially at pH 5. X-ray absorption fine structure spectroscopy analyses confirmed the precipitation of Zn-S as sphalerite and Cu-S as covellite in all samples, but also revealed the presence of Zn sorbed on hydroxyapatite. These analyses further showed that CuS structures remained amorphous regardless of the pH, whereas the ZnS structure was more organized at pH 5 as compared to the ZnS formed at pH 3 and 7, in agreement with the cubic sphalerite-type structures observed through scanning electron microscopy at pH 5.

KIT gene molecular analysis distinguishes multiple primary GIST from metastatic disease

10048

Background: The occurrence of multiple primary GIST (MPG) has been reported exclusively in children and in NF1 patients. However, sometimes adult GIST patients present at onset with double lesions raising the problem of the differential diagnosis between metastatic and MPG. Morphologic features might help in recognizing MPG. A clear cut distinction is much less obvious when dealing with simultaneous high risk lesions. Molecular analysis of KIT gene may represent an important tool to discriminate among these two possibilities, allowing proper therapeutic strategies. Methods: From a series of 200 GIST we selected 5 non NF1 adult GIST patients, presenting double lesions at onset. Genomic DNA was extracted from both the nodules of each patients and exons 9, 11, 13, 14 and 17 of KIT gene were sequenced. Cases were also investigated for KIT exon 10 and intron 10 and PDGFRA exons 12 and 18. Results: Age ranged from 48 to 82 years. Four patients had a dominant nodule, ranging in size between 3 and 10 cm, and a peritoneal/hepatic nodule ranging in size between 0.8 and 3 cm. One patient had one gastric and one small intestinal nodules of 6 cm. No significant differences in mitotic rate and morphology were seen between the two nodules in each case. In two cases, both nodules showed same molecular profile, confirming the metastatic nature of the disease. In one case, the same KIT mutation was detected in both lesions, but an additional mutation was present only in the intestinal tumor. In contrast, in one case, different KIT mutations were found, suggesting the occurrence of two synchronous GIST. In an additional case, while a PDGFRA mutation was found in the tumor located in the stomach, no mutations were detected in the tumor located in the liver. Conclusions: 1. Molecular analysis proves the existence of exceptional cases of multiple primary GIST in non children, non NF1 patients. 2. Since discrimination between metastatic disease at onset and multiple primaries impacts over therapeutic strategies, it might be useful also in the routine practice to perform molecular analysis of both nodules in cases of double GIST.

No significant financial relationships to disclose.

Twist is substrate for caspase cleavage and proteasome-mediated degradation

Twist is a member of the basic helix-loop-helix family of transcription factors. An aberrant Twist expression has been found in diverse types of cancer, including sarcomas, carcinomas and lymphomas, supporting a role for Twist in tumor progression. Twist is known to be essential for mesodermal development. However, since a prolonged Twist expression results in a block of muscle, cartilage and bone differentiation, Twist has to be excluded from somites during late embryogenesis for terminal differentiation to occur. This implies that Twist expression must be target of a tight control. Here we provide evidence that Twist undergoes post-transcriptional regulation. Twist is substrate for cleavage by caspases during apoptosis and its cleavage results in ubiquitin-mediated proteasome degradation. Our findings suggest that Twist post-transcriptional regulation may play an important role in tissue determination and raise the possibility that alterations in the protein turnover may account for Twist overexpression observed in tumors.

Caspase activation and apoptosis in response to proteasome inhibitors

Several studies have indicated that proteasome inhibitors (PIs) are promising anticancer agents. We have discovered that PIs have the unique ability to activate effector caspases through a mitochondrial Bcl-2 inhibitable but caspase-9 independent pathway. Stabilization of released Smac induced by blockade of the proteasome could explain the apoptosome-independent cell death induced by PIs. In fact, Smac/DIABLO critically supports this PIs-dependent caspase activation. By using a new assay, we confirm that at a single cell level both Smac and PIs can activate caspases in the absence of the apoptosome. Moreover, we have observed two PIs-induced kinetics of caspase activation, with caspase-9 being still required for the rapid caspase activation in response to mitochondrial depolarization, but dispensable for the slow DEVDase activation. In summary, our data indicate that PIs can activate downstream caspases at least in part through Smac/DIABLO stabilization.

Coordinated expression and amplification of the MDM2, CDK4, and HMGI-C genes in atypical lipomatous tumours

Atypical lipomatous tumours (ALTs) represent a distinctive subset of mesenchymal neoplasms featuring mature adipocytic differentiation. Most ALTs are characterized cytogenetically by the presence of supernumerary ring and/or long marker chromosomes derived from the chromosomal region 12q13-15. The 12q13-15 chromosome region contains several genes which may play an important role in human tumorigenesis. A series of ALTs was analysed by investigating the MDM2, CDK4, and HMGI-C genes and their proteins. The study was extended to a series of ordinary lipomas, to determine whether the immunohistochemical investigation of these gene products might play any diagnostic role. Cytogenetic analysis revealed the presence of various cytogenetic aberrations involving the 12q13-15 region in 11/18 (61%) lipomas and of ring chromosomes in all ALTs. Overexpression of mdm2 protein was observed in 6/12 (50%) atypical lipomatous tumours. All lipomas were mdm2-negative. cdk4 overexpression was present in 100% of ALTs. Weak cdk4 immunopositivity was detected in 2/18 (11%) ordinary lipomas in a minority of cells. HMGI-C immunopositivity was observed in 10/12 (83%) ALTs. Positive immunoreactivity was also observed in 8/18 (44%) lipomas. Southern blot analysis revealed amplification of the CDK4 and MDM2 genes in 3/5 ALTs analysed. HMGI-C was amplified in 3/5 cases and was deleted in one case. Mutation analysis of the CDK4 gene did not demonstrate any mutation. These data support the hypothesis that ordinary lipomas may form a molecular genetic and morphological continuum with ALT. At one end of the spectrum are lipomas characterized by 12q13-15 rearrangements and HMGI-C activation and at the other end are ALTs with ring chromosomes, 12q13-15 amplification with overrepresentation of the HMGI-C, CDK4 or MDM2 genes, and aberrant cdk4, mdm2, and HMGI-C protein expression. These findings not only provide insights into the molecular pathogenesis of lipomatous tumours, but also indicate that the immunohistochemical analysis of mdm2 and cdk4 may help to increase diagnostic accuracy.

Twist is a potential oncogene that inhibits apoptosis

Oncogene activation increases susceptibility to apoptosis. Thus, tumorigenesis must depend, in part, on compensating mutations that protect from programmed cell death. A functional screen for cDNAs that could counteract the proapoptotic effects of the myc oncogene identified two related bHLH family members, Twist and Dermo1. Both of these proteins inhibited oncogene- and p53-dependent cell death. Twist expression bypassed p53-induced growth arrest. These effects correlated with an ability of Twist to interfere with activation of a p53-dependent reporter and to impair induction of p53 target genes in response to DNA damage. An underlying explanation for this observation may be provided by the ability of Twist to reduce expression of the ARF tumor suppressor. Thus, Twist may affect p53 indirectly through modulation of the ARF/MDM2/p53 pathway. Consistent with a role as a potential oncoprotein, Twist expression promoted colony formation of E1A/ras-transformed mouse embryo fibroblasts (MEFs) in soft agar. Furthermore, Twist was inappropriately expressed in 50% of rhabdomyosarcomas, a tumor that arises from skeletal muscle precursors that fail to differentiate. Twist is known to block myogenic differentiation. Thus, Twist may play multiple roles in the formation of rhabdomyosarcomas, halting terminal differentiation, inhibiting apoptosis, and interfering with the p53 tumor-suppressor pathway.

Loss of heterozygosity at 10q in tumors of the upper respiratory tract is associated with poor prognosis

Frequent loss of a specific chromosomic region in cancers is often associated with inactivation of a tumor-suppressor gene. The long arm of chromosome 10 is deleted in several types of tumor, among them squamous-cell carcinomas of the head and neck (HNSCC). To determine the role of 10q deletions in the tumorigenesis of the upper respiratory tract, 47 HNSCCs were examined for loss of heterozygosity (LOH) at 10q: 43% of the cases analyzed showed LOH at 10q, and 2 distinct hot spots of deletion were identified, at 10q22-23 and 10q25-26. The possible involvement of pTEN/MMAC1, a tumor-suppressor gene mapped at 10q23, was also evaluated. No mutation, homozygous deletion or loss of expression of pTEN/MMAC1 was detected, indicating that inactivation of this gene plays a minor role in HNSCC development. Interestingly, the frequency of deletion at 10q was greater in invasive carcinoma than in adjacent carcinoma in situ, and a significant association between LOH and poor prognosis was observed. Taken together, our results suggest the presence in the long arm of chromosome 10 of (a) tumor-suppressor gene(s) other than pTEN/MMAC1 and presumably involved in the malignant progression of tumors of the upper respiratory tract. Int. J. Cancer (Pred. Oncol.) 84:432-436, 1999.

Microsatellite instability in squamous cell carcinomas of the head and neck related to field cancerization phenomena

Patients affected by squamous cell carcinoma of the head and neck (HNSCC) show frequent occurrence of multiple cancers and widespread precancerous lesions in the mucosa of the upper respiratory tract, a phenomenon known as field cancerization. In this study, we investigated the role of genetic instability in the development of HNSCC and in particular in tumour multiplicity phenomena of the upper respiratory tract. For this purpose, we analysed microsatellite instability (MI) and loss of heterozygosity (LOH) at 20 loci mapping on five chromosomal arms in 67 HNSCC patients, 45 of whom had a single cancer and 22 had multiple primary tumours. The possible involvement of the hMLH1 gene in genetic instability and as a potential target of 3p21 deletion phenomena in head and neck cancers was also investigated. Our data indicate that mismatch repair-related genetic instability plays a minor role in the carcinogenesis of HNSCC and in tumour multiplicity of the head and neck region. Moreover, our results exclude a role for the hMLH1 gene as a determinant of MI and as a specific gene target of deletion at 3p21 in HNSCC. We conclude that presumably other genetic mechanisms, such as those hypothesized for MI-negative hereditary non-polyposis colorectal cancer patients, may play a major role in the carcinogenesis of the mucosa of the upper respiratory tract.

Overexpression of CDC25A and CDC25B in head and neck cancers

The deregulation of several cell cycle-related genes participates in neoplastic transformation. Cell cycle progression is driven by cyclin-dependent kinases, which are positively regulated by association with cyclins and negatively regulated by binding to inhibitory subunits. The activity of cyclin-dependent kinases is also regulated by the phosphorylation status, which is controlled by the antagonistic action of wee1 kinase and CDC25 phosphatases. Three CDC25 genes are present in human cells: CDC25A, CDC25B, and CDC25C. These three genes function at different phases of the cell cycle. Whereas CDC25A and CDC25B are expressed throughout the cell cycle, with peak expression in G1 for CDC25A and in both G1-S-phase and G2 for CDC25B, CDC25C is predominantly expressed in G2. Several lines of evidence suggest a role for CDC25s as oncogenes. CDC25A and CDC25B cooperate with Ha-ras or loss of Rb1 in the oncogenic transformation of rodent fibroblasts. Moreover, they are transcriptional targets of c-myc, and CDC25A in particular plays an important role as a mediator of myc functions. On the basis of the evidence that CDC25 phosphatases can act as oncogenes, we analyzed the expression of CDC25A, CDC25B, and CDC25C genes in 20 squamous cell carcinomas of the head and neck by quantitative reverse transcription-PCR. Our results show that whereas CDC25C is expressed at a low level with no relevant differences between neoplastic tissue and normal mucosa, CDC25A and CDC25B are overexpressed in a large fraction of tumors.

Human non-Hodgkin's lymphomas overexpress a wild-type form of p53 which is a functional transcriptional activator of the cyclin-dependent kinase inhibitor p21

A large fraction of non-Hodgkin's lymphomas (NHLs) accumulate a wild-type form of the p53 tumor suppressor protein at the nuclear level. In normal cells, p53 induction is associated with a temporary cell growth arrest at the G1-S boundary of the cell cycle. This activity of p53 as a G1 checkpoint molecule is strictly dependent on its ability to induce the transcription of the inhibitor of the cyclin dependent kinase, p21. To verify the functionality of the wild-type p53 protein accumulated in NHL cells, 70 cases were comparatively analyzed for p53 and p21 expression and status of the respective genes. Overexpression of the wt p53 protein was associated with the accumulation of p21, indicating that p53 is functional with respect to p21 induction in these tumors. The coaccumulation of p53 with Ki-67 antigen indicates that wt p53-positive cells and p21-positive cells, as well, are actively proliferative elements, supporting the notion that p53-induced, p21-mediated growth arrest is somehow overridden in NHL cells. No p21 mutation or particular allele variant was shown to correlate with p21 protein accumulation, thus excluding a role for p21 structural abnormalities. Taken together, our data suggest the existence in NHL of a peculiar mechanism of functional inactivation of the p53 G1 checkpoint pathway occurring downstream of the CDK inhibitor p21.

p16/CDKN2 and CDK4 gene mutations in sporadic melanoma development and progression

The p16/CDKN2(MTS1) gene encoding for the p16 inhibitor of cyclin D/CDK4 complexes is frequently mutated and deleted in a large fraction of melanoma cell lines, and p16 germline mutations have also been observed in familial melanomas. Moreover, a CDK4 gene mutation, responsible for a functional resistance of CDK4 kinase to p16 inhibitory activity, has been described to occur in some cases of familial melanoma. These data strongly support the idea that deregulation of the CDK4/cyclin D pathway, via CDKN2 or CDK4 mutations, is of biological significance in the development of melanoma. To shed light on the role of these alterations in the development and progression of sporadic melanoma, 12 primary melanomas and 9 corresponding metastases were analyzed for CDKN2 and CDK4 gene mutations. Of the 12 primary melanomas analyzed, 4 showed the presence of mutational inactivation of the p 16 protein and 2 carried silent mutations. No metastases showed the presence of CDKN2 mutations, indicating that mutations of this cyclin-dependent kinase inhibitor is not common in the progression of sporadic melanoma. On the other hand, the absence, in the metastases, of the CDKN2 mutation detected in the corresponding primary tumors suggests that 9p21 homozygous deletion may play a major role in the metastatic spreading of this type of tumor. None of the cases analyzed showed the presence of an Arg24Cys mutation, which functionally protects CDK4 from p16 inhibition. This indicates that CDK4 mutation plays a minor role in the development and progression of sporadic melanoma.

All-TRANS, 13-CIS and 9-CIS retinoic acids induce a fully reversible growth inhibition in HNSCC cell lines: Implications forin vivo retinoic acid use

Retinoids are a group of vitamin A analogues that have shown promise as chemopreventive and therapeutic agents in many types of malignancy and have been entered in clinical trials with some successful results. To better understand the mechanism that mediates retinoid action and the anti-proliferative effects, we treated 7 human oral squamous-cell carcinoma (SCC) cell lines (FADU, HEp-2, CCL-17, SCC-9, SCC-15, SCC-25 and HN-212) with 10(-6) M of all-trans retinoic acid (ATRA), 9-cis and 13-cis retinoic acid (RA) in continuous for different periods of time. We assessed the extent of growth inhibition, the stability of the anti-proliferative effect and the mRNA expression levels (by RT-PCR) of RA receptors (RARs), retinoid X receptors alpha (RXR alpha) and cytosolic RA-binding proteins (CRBP I and CRABP II) in treated cells compared with controls. The data obtained showed that all 3 RAs were able to inhibit the cellular growth of the tested cell lines, although to a different extent. The cis compounds were able to inhibit the proliferation of all cell lines, whereas ATRA was ineffective in inhibiting the proliferation of the CCL-17 cell line, which was naturally resistant to ATRA concentrations in the range between 10(-5) and 10(-6) M. All inhibitory effects were completely reversible since all cell lines restored their normal growth proliferation within few days after drug removal. RT-PCR analysis of the receptor and cell binding protein status of control and treated cells showed a good correlation between growth inhibition and induction of, or increase in, the expression levels of RAR beta in RA-treated cells. No differences were observed in RAR alpha and RXR alpha mRNA expression levels between control and treated cells. CRBP I, CRABP II and RAR gamma mRNA levels increased in some treated cell lines but not in all.

Molecular abnormalities of the p53 pathway in dedifferentiated liposarcoma

Dedifferentiated liposarcoma represents a distinct subtype of liposarcoma and is characterized by the presence of abrupt transition from well-differentiated liposarcoma to high-grade pleomorphic sarcoma (mostly MFH-like). A key role for p53 in tumour progression of this subset of liposarcomas has been suggested on the basis of p53 immunopositivity. A series of 14 dedifferentiated liposarcomas has been investigated by analysing the p53 gene and protein together with the p53-related molecules p21Waf1 and mdm2, to verify whether the p53 pathway is involved in the development and progression of this tumour type. The results indicate that the p53 gene is rarely involved in dedifferentiated liposarcoma (7 per cent of cases analysed) and that low percentages of p53 immunopositivity are still compatible with integrity of the p53 gene. This concept is also supported by the observed preservation of p21Waf1 immunoreactivity in all but the p53-mutated cases. By contrast, mdm2 overexpression emerges as the most frequent abnormality in dedifferentiated liposarcoma (57 and 78 per cent of cases in well-differentiated and high-grade areas, respectively).

Tumor suppressor genes and related molecules in leiomyosarcoma

Soft tissue sarcomas represent a heterogeneous group of mesenchymal malignancies, and the majority of the previous scientific studies that have analyzed the occurrence of cell cycle regulators aberrations within soft tissue sarcomas have dealt with broad categories of different tumors. As a consequence, data concerning single classes of sarcomas are very limited. The authors analyze herein a histologically homogeneous series of 23 cases of leiomyosarcoma of the deep soft tissue. The p53 pathway was studied by investigating the p53 gene and protein, MDM2 protein, and p21waf1 protein. The Rb-cyclin D pathway was analyzed by studying the Rb gene and protein, p16MTS1/INK4A gene and protein, cyclin D1Prad1/bcl1 and cyclin D3 proteins. Aberrations of the p53 pathway were observed in about 16 percent of cases and were limited to the p53 gene. Such a finding contrasts with the higher rates of p53/MDM2 abnormalities reported in other types of sarcomas such as liposarcoma. Interestingly, abnormalities involving the Rb-cyclin D pathway were detected in about 90 percent of cases. The Rb-cyclin D pathway therefore emerges as the preferred target for molecular abnormalities in this subset of soft tissue sarcomas.

Chromosome 13q deletion mapping in head and neck squamous cell carcinomas: identification of two distinct regions of preferential loss

Heal and neck squamous cell carcinomas show frequent cytogenetic alterations involving the long arm of chromosome 13. To define the extent of 13q deletions and to identify the minimal areas of chromosome loss, 48 primary squamous cell carcinomas of the head and neck were analyzed for loss of heterozygosity using 11 different polymorphic loci. About 67% of the tumors displayed loss of genetic material at 13q. Most of the cases showed loss of the entire long arm of the chromosome. However, the presence of partial deletions in 10 cases provided evidence of the existence of two preferential sites of chromosome loss at 13q32-ter and 13q14.2-q14.3. The colocalization of the 13q14 minimal region of deletion with the retinoblastoma (RB) gene, which has been proposed as an oncosuppressor in diverse tumor types, prompted us to verify the involvement of this gene in the development of head and neck cancer. No significant variation in RB protein or RB mRNA expression was detected, thus excluding a role for such a gene in the genesis of this type of tumor. Taken together, our data suggest the existence of two new tumor suppressor genes (one close to and one distal to RB), which play a role in the development and/or progression of head and neck squamous cell carcinomas.

Immunophenotypic and molecular analyses of acquired immune deficiency syndrome-related and Epstein-Barr virus-associated lymphomas: a comparative study

Limited information is current available on the molecular and immunophenogenotypic characteristics of CD30-positive anaplastic large cell (ALC) lymphomas occurring in human immunodeficiency virus (HIV)-infected individuals. To address this issue, the authors have undertaken a combined analysis of these lymphomas in a comparison with other Epstein-Barr virus (EBV)-associated tumors in the setting of HIV infection. Twenty-one AIDS-related lymphomas, including five CD30-positive ALC and 11 small noncleaved cell (SNCC) lymphomas, and five Hodgkin's disease (HD) specimens were characterized regarding the immunophenogenotypic features, the frequency and subtype distribution of EBV (as defined by in situ hybridization [ISH], Southern blot, and a polymerase chain reaction [PCR] amplification of the EBV nuclear antigen-2 [EBNA-2] region) antigen expression (latent membrane protein-1 [LMP-1], EBNA-2, and for alterations of the tumor suppressor gene p53. Combined immunophenotypic and immunogenotypic analyses showed a derivation from anomalously matured B cells in four of five CD30-positive ALC lymphomas, whereas SNCC showed features of mature B cells; no evidence of immunoglobulin or TCR gene rearrangement could be obtained in HD cases. Combined ISH and Southern blot analyses revealed that EBV was more strictly associated with HD (five of five) and CD30-positive ALC lymphomas (four of five) than with SNCC lymphomas (four of 11). EBV-positive samples from CD30-positive ALC lymphomas carried type 1 EBV (two of two specimens tested), whereas both EBV subtypes were observed in SNCC lymphomas and HD samples. All three forms of viral latent gene expression were found in the EBV positive CD30-positive ALC lymphomas. SNCC specimens did not express LMP-1 or EBNA-2, whereas HD specimens expressed LMP-1 (four of five tested) but no EBNA-2. Immunostaining for ZEBRA was consistently negative. HHV-6 DNA sequences were detected by PCR in one SNCC of the 19 specimens analyzed. Three out of five CD30-positive ALC lymphoma specimens and six of 10 SNCC showed nuclear staining for p53. No mutation was detected in any of the three CD30-positive Alc lymphoma analyzed, whereas an aberrant SSCP pattern was found in all the four SNCC samples tested. At variance with SNCC lymphomas, AIDS-related B-cell CD30- positive ALC lymphomas are strictly associated with EBV infection and may also express the broad lymphoblastoid cell line-like (LMP-1-positive, EBNA-2-positive) pattern, and lack p53 genetic lesions. Unlike EBV, HHV-6 probably does not represent a relevant factor involved in the pathogenesis of CD30-positive ALC and other HIV related lymphomas.

Recurrences and second primary tumours in the head and neck region: differentiation by p53 mutation analysis

BACKGROUND

Patients with head and neck cancer are at high risk of developing additional primary tumours in the aerodigestive tract as a result of field cancerization phenomena. In this context, the appearance of a new neoplasm often poses a problem of differential diagnosis between recurrence and new primary tumour. The differentiation between the two entities in essentially clinical and conventionally based on the histological and spatio-temporal relations between the two lesions; however, the validity of these criteria has still to be assessed.

DESIGN

To evaluate whether field cancerization phenomena may affect the clinical diagnosis of relapse/metastasis in the head and neck region, p53 mutation pattern was analysed in a series of primary tumours and corresponding recurrences/metastases. The rationale was that, since p53 mutations are a very early and polymorphic phenomenon, a recurrence/metastasis must retain the same mutation as the the primary tumour, whereas independent tumours are likely to display a different p53 gene status.

RESULTS

Molecular analysis provided conclusive results in 9 of 12 cases analysed. The clinical diagnosis of recurrence was confirmed by molecular analysis in 4 of these cases. In contrast, a differential p53 mutation pattern supported an independent origin for 3 presumed local recurrences and 2 lung lesions.

CONCLUSIONS

The use of p53 mutation analysis as a clonality marker allowed us to ascertain the inadequacy of the current diagnostic criteria for the differentiation between a new independent tumour and recurrence/metastasis. These findings substantiate the relevance of field cancerization phenomena in the head and neck region and prompt the use of p53 mutation analysis as a fundamental tool to improve the diagnosis and management of head and neck cancers.

Spontaneous Mutation of Cell Oncogenes Plays a Minor Role in Neoplastic Transformation of Virus-Induced Murine T-Cell Lymphomas

Mink cell focus-forming viruses (MCF) are slow-transforming retroviruses that are able to accelerate the appearance of T-cell lymphomas when injected in newborn AKR mice. Activation of proto-oncogenes by proviral insertion is thought to be the major mechanism by which these viruses exert their oncogenic potential. However, molecular phenomena not strictly virus-determined, such as mutations in cellular oncogenes/tumor suppressor genes or chromosome aberrations, have been hypothesized to contribute to the achievement of the fully neoplastic phenotype in MCF-infected mice. To evaluate the role of spontaneous mutagenesis phenomena in murine virus-induced lymphomagenesis, we analyzed a series of 18 MCF247-induced thymic lymphomas and derived cell lines for the presence of p53 and c-ras gene mutations. Only 1 mutation at the p53 gene and 1 mutation at the ki-ras gene were detected in our study. Our results suggest that spontaneous mutagenesis plays a minor role in virus-induced lymphomagenesis and support the notion that multiple proviral insertions could be the prevalent mechanism of transformation in this experimental system.

MDM2 overexpression does not account for stabilization of wild-type p53 protein in non-Hodgkin's lymphomas

p53 protein overexpression is a frequent finding in non-Hodgkin's lymphomas (NHL), being detected in over 25% of the cases. Moreover, some high-grade lymphomas and a large fraction of low-grade tumors show a pattern of scattered p53 accumulation in a limited percentage of neoplastic cells. In contrast, NHLs show a low frequency of p53 gene mutations. To investigate the molecular bases of p53 protein overexpression, a large series of NHLs was analyzed for p53 gene status. The analysis of the entire coding region of the gene (exons 2-11) and corresponding donor and acceptor splicing sites indicated that a significant proportion of p53-positive tumors overexpresses a wild-type form of p53 protein (wt-p53). To assess whether wt-p53 accumulation was related to the formation of inactive complexes with endogenous proteins, MDM2 oncogene expression and amplification were analyzed. MDM2 overexpression was detected only in one third of the wt-p53-positive cases, thus excluding that MDM2 accounts tout court for the accumulation of a normal p53 protein. However, the fact that MDM2 overexpression was detected in only the p53-positive cases and the observation that MDM2-positive cells were a subpopulation of p53-positive cells suggest a link between the two phenomena. In particular, our results indicate that the accumulation of a wt form of p53 protein could promote the overexpression of the MDM2 gene product. In addition, the prevalence of MDM2 positivity in intermediate/high-grade tumors together with the concordant expression of wt-p53 and MDM2 only in the high-grade component of a 'composite' lymphoma suggests that perturbation in the MDM2/p53 critical ratio could play a role in lymphoma progression.

Analysis of the p53 gene in relation to tobacco and alcohol in cancers of the upper aero-digestive tract

To elucidate the relationship, if any, of p53 gene expression according to smoking and drinking habits, 135 subjects with cancer of the upper aero-digestive tract were sampled from a case-control investigation conducted in Pordenone province, Northeast Italy, between 1986 and 1991. Adequate pathological material for immunohistochemical analysis was available for 83 subjects. Level of p53 expression was classified according to intensity on immunoreaction and percentage of p53-positive cells. Mutations were analyzed by means of single-strand conformation polymorphism and sequencing in 8 p53-positive life-long non-smokers exposed to various levels of alcohol intake. The association between p53 expression and smoking status and alcohol intake was evaluated by means of odds ratios, and 95% confidence intervals. Significantly, more men (39/65) than women (6/18) had elevated p53 expression. No significant trend of increasing percentage of p53-positive cancers with increasing smoking and drinking level was detected, especially after allowance for gender. With respect to specific mutation pattern, in 8 life-long non smokers who drank alcohol, 6 mutations involved G:C base pairs. G-to-A transitions were identified in 4 cases. The present study does not support an association between elevated p53 expression and tobacco smoking or alcohol intake. It provides an example of a molecular biology study in the framework of a large epidemiological investigation.

Ultraviolet-induced p53 mutations in atypical fibroxanthoma

Atypical fibroxanthoma (AFX) is an uncommon neoplasm of the superficial soft tissue occurring in actinically damaged skin of elderly patients. Sun-exposed skin also represents the main site of squamous and basal cell carcinomas and malignant melanoma, and a key role for ultraviolet (UV) radiation in their pathogenesis has long been suspected. UV-related mutations of the p53 gene have been identified in human skin cancers. To verify whether the pathogenesis of AFX is related to the effect of sunlight, p53 protein and gene status have been investigated in a series of 10 cases of AFX. Seven of 10 showed p53 immunoreactivity in most of the neoplastic cells. Molecular analysis of the p53 gene revealed an abnormal single strand conformation polymorphism pattern in all the p53 positive cases. Polymerase chain reaction direct sequencing revealed that all the mutations involved cytosine bases. Four cases showed C to T transitions (including two CC-TT double base substitutions) and two cases showed C to G transversion. All but one mutation took place at dipyrimidine sites. These findings provide the first objective evidence for the central role of UV radiation in the development of AFX and also represent the first in vivo demonstration of solar UV-induced mutations in a human mesenchymal neoplasm.

p53 protein over-expression and p53 gene abnormalities in HIV-1-related non-Hodgkin's lymphomas

Alteration of the p53 tumor-suppressor gene was studied in non-Hodgkin's lymphomas (NHLs) from HIV-1-infected patients. p53 protein was over-expressed in 10 out of the 45 (22%) cases analyzed, mainly clustering in the small-non-cleaved-cell (SNC) (5/19) and Ki-1+ anaplastic large-cell (ALC) (3/8) sub-types, according to previous findings on HIV-1-unrelated NHLs. p53-positive small-non-cleaved-cell lymphomas presented a diffuse or clustered pattern of p53-positive neoplastic cells consequent upon p53-gene mutations. In contrast, in Ki-1+ ALC lymphomas p53 immunohistochemical reactivity was limited to scattered tumor cells, and no p53-gene alterations could be detected. These results suggest that p53-gene alterations play a role in the lymphomagenetic process of a fraction of HIV-1-related SNC NHLs, however with a frequency no different from that observed in HIV-1-unrelated NHLs of the same sub-type. In HIV-1-related Ki-1+ ALC lymphomas, mechanisms different from gene alterations might be implicated in over-expression of p53 protein.

In vivo phenotypic characteristics of AKR T-cell lymphomas with different leukemic potential: possible role of alpha 4 beta 7 integrin in the progression towards the leukemic phenotype

The present study was undertaken in order to determine whether the expression of specific surface molecules which mediate immune recognition as well as cell-cell and cell-matrix interactions is associated with the leukemic evolution of T-cell lymphomas. To this end, we have investigated the in vivo phenotypic characteristics and the in vitro natural-killer(NK)-cell susceptibility of a group of MCF-247-induced AKR/J T-cell lymphomas with different leukemic potential. We found that in the AKR/J model, the biological aggressiveness of leukemic cells is not dependent upon an escape from host immune surveillance as a consequence of an in vivo down-regulation of H2-Kk determinants or a resistance to NK lysis. Moreover, NK susceptibility of AKR/J lymphomas does not seem to correlate with the level of H2-antigen expression. No obvious correlation was found between the leukemic phenotype and the amount of MEL-14, LFA-1, ICAM-1, Pgp-1/CD44 and THAM/CD26 antigen expression. An in vivo coordinated up-regulation of alpha 4 and beta 7 integrin chains, with the highest levels of expression detected in secondary sites of leukemic infiltration, was observed in the highly leukemic lymphoma NQ22 and, albeit to a lesser extent, in lymphomas with moderate leukemic potential. Conversely, non-leukemic lymphomas were repeatedly alpha 4- and beta 7-negative. These findings suggest that in the AKR/J system the expression of alpha 4 beta 7 integrin may contribute to leukemic spreading of T-cell lymphomas.

Three discrete regions of deletion at 3p in head and neck cancers

Alteration of the short arm of chromosome 3 is one of the most consistent cytogenetic abnormalities found in human head and neck cancers. These alterations, composed of translocations and deletions, have been associated with the presence of a tumor suppressor gene(s), but no clear evidence of the location of this presumptive gene(s) was available. We performed a molecular analysis of the 3p region using a polymerase chain reaction-based approach. Twenty-eight of the 38 cases analyzed (74%) showed the presence of single or multiple areas of allelic loss. Three commonly deleted regions, tentatively mapped to 3p24-ter, 3p21.3, and 3p14--cen, were identified. Our results suggest that at least three oncosuppressor genes mapping on 3p may be involved in head and neck cancer development and support a common oncogenic pathway with squamous cell lung cancer, for which a similar pattern of 3p deletion has been described recently.

p53 over-expression is an early event in the development of human squamous-cell carcinoma of the larynx: genetic and prognostic implications

The tumor-suppressor protein p53 is over-expressed in a large fraction of squamous-cell carcinomas of the larynx (LSCCs). p53 overexpression is dependent upon the synthesis of mutated versions of the protein and has been associated with the malignant progression of certain tumor types. In order to examine the prognostic value of p53 immunodetection in LSCCs, we performed a retrospective analysis on a selected series of tumors, using the PAb 1801 and CM1 antibodies. No significant difference in the frequency of p53 over-expression was observed between tumors from patients with early relapse (67%) and those who had been disease-free for more than 5 years (84%). The lack of correlation of p53 immunoreactivity with clinical stage and differentiation grade of LSCCs, together with the coordinated expression of p53 in primary tumors and the corresponding lymph-node metastases, indicate that p53 over-expression is probably unrelated to the biological aggressiveness of these tumors. In addition, the detection of p53 immunostaining in pre-invasive areas as well as in preneoplastic lesions suggests that p53 abnormalities probably constitute a very early event in LSCC development.

High frequency of p53 gene alterations associated with protein overexpression in human squamous cell carcinoma of the larynx

A series of 58 primary human squamous cell carcinomas of the larynx (LSCCs) was examined for the expression of the p53 tumor-suppressor gene by a combined immunohistochemical and molecular approach. About 60% of the cases displayed nuclear p53 overexpression as revealed by immunostaining with PAb1801, PAb122 and PAb240 monoclonal antibodies. This phenomenon was associated with the presence of structural and/or transcriptional alterations of the p53 gene. Our results provide evidence that p53 abnormalities constitute the most frequent genetic alteration identified so far in LSCC and indicate that the abnormal accumulation of the protein correlates with the presence of p53-mutated versions. These findings, taken together with the peculiar biochemical properties of p53, support the hypothesis of a possible pathogenetic relationship between smoke carcinogen exposure and p53 inactivation in the development of this tumor type.

Expression of the mdr1 gene in human colorectal carcinomas: relationship with multidrug resistance inferred from analysis of human colorectal carcinoma cell lines

To investigate whether mdr1 gene products are involved in conferring the chemoresistant phenotype to human colorectal carcinomas (HCCs), we determined the mdr1 mRNA expression level (mdr1 EL) in surgical specimens from 29 pharmacologically untreated patients and analyzed the relationship between mdr1 EL and drug resistance in an in vitro experimental model. This consisted of 7 HCC cell lines chosen to cover the range of mdr1 ELs detected in the neoplastic specimens. No relationship was observed between the mdr1 EL of the HCC cell lines and the degree of chemosensitivity found for each drug tested, regardless of whether mdr1 gene products may [doxorubicin (DOX), vincristine (VCR), and actinomycin-D (ACT-D)] or may not affect [cis-diamminedichloroplatinum (CDDP)] drug-transmembrane equilibria. Conversely, a direct relationship was found between the mdr1 EL of HCC cell lines and the number of drug-resistant (DR) colonies arising from each parent cell line treated in continuous culture with high DOX concentrations. In addition, the chemoresistance index and mdr1 EL of the DR cell variants were roughly proportional to the mdr1 EL of the parent cell line. Our findings suggest that primary HCCs derive multidrug resistance from biochemical mechanism(s) other than mdr1 gene products. However, the mdr1 EL might be indicative of a predisposition to develop DR cell variants after chemotherapeutic treatment.

Adhesion molecule expression does not influence the leukemic behavior of murine T-cell lymphomas

Recirculation and homing properties of normal lymphocytes are controlled by interactions with high endothelial venules (HEVs), specialized vessels which mediate the extravasation into lymphoid tissues. The present study was aimed at elucidating whether lymphoma-derived leukemic cell spreading and peripheral lymph node invasion ability are mediated by the recognition mechanisms which physiologically regulate normal lymphocyte trafficking. For this purpose, we tested the HEV-binding ability and the expression of the lymphocyte homing receptor (LHR) for peripheral lymph nodes as well as Pgp-1/CD44, LFA-1 and ICAM-1 adhesion molecules by the highly leukemic cell line NQ22 in comparison with a series of non-leukemic murine T-lymphoma cell lines. Our results indicate that the hematogenous spreading as well as peripheral node invasion of lymphoma-derived leukemic cells may occur independently of LHR expression. In addition, our findings seem to rule out that gross quantitative modifications in LFA-1 or ICAM-1 antigen expression are associated with differential dissemination abilities of transformed lymphoid cells.

Proto-oncogene allelic variations in human squamous cell carcinomas of the larynx

Proto-oncogene restriction fragment length polymorphisms (RFLPs) were investigated in a group of 23 patients with squamous cell carcinomas of the larynx. The frequency of the rare 5 kb c-mos allele was significantly higher than that observed in control groups of patients with colorectal neoplasms or lymphoproliferative disorders. In addition, the 2 patients heterozygous at the c-mos locus (TC-8 and TC-10) were the only 2 of our series of develop multiple malignancies. Also, the 10 kb L-myc allele was remarkably more represented in patients with laryngeal carcinoma when compared to controls. These findings suggest that c-mos and L-myc RFLPs might be helpful in identifying those individuals who are at a higher risk of developing laryngeal carcinomas. Single allele amplification of L-myc, c-myb and c-mos proto-oncogenes, with no concomitant mRNA hyperexpression, were observed in 3 cases. The results obtained seem to rule out a direct pathogenetic role of these proto-oncogenes and suggest that the amplification of other closely linked genes, located on chromosomes 1, 6 and 8, respectively, may be causally associated with the development of these tumors. No allelic deletions at the c-myb locus were observed, whereas a loss of a c-Ha-ras-1 allele was demonstrated in one of the 11 heterozygous patients. Thus, the analysis of polymorphic proto-oncogenes in laryngeal carcinomas allowed us to identify a group of genetic abnormalities (chromosomes 1, 6 and 8 gene amplifications and c-Ha-ras-1 deletions) which may be involved in the development or progression of these tumors.

Correlation between chromosome 5q deletions and different mechanisms of c-myc overexpression in human colorectal cancer

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Establishment and characterization of a leukemic murine cell line derived from MCF 247 MuLV-induced T-cell lymphoma

Understanding of the leukemic evolution of human non-Hodgkin's lymphomas is hindered by the lack of appropriate animal models. For this purpose, a highly leukemic cell line NQ22, derived from a MCF 247 murine leukemia virus (MuLV)-induced murine T-cell lymphoma, was established, and its preliminary characterization is described. The NQ22 cell line is easily transplantable subcutaneously (s.c.) into syngeneic AKR mice exhibiting early peripheral blood invasion and widespread dissemination with a leukemic pattern of infiltration. Such peculiar in vivo behavior is a stable phenotypic feature, probably determined genetically. Biological and differentiation characteristics of the NQ22 cell line were analyzed and compared to those of other non-leukemic T-lymphoma lines. In addition, no evidence of possible involvement of plasminogen activator (PA) enzymes and of their inhibitors (PAI) in the spreading ability of NQ22 cells was observed.

c-myc overexpression is a tumor-specific phenomenon in a subset of human colorectal carcinomas

The transcriptional activity of the c-myc proto-oncogene was examined in 25 primary human colorectal carcinomas and their corresponding normal mucosae. The purpose was to determine whether the elevated levels of c-myc expression, frequently detected in this type of tumor, might be the consequence of alterations in the cell growth rate or the effect of a real transcriptional deregulation of the gene. In about 44% of the tumors the elevated c-myc expression was consequent to the enhanced growth rate of the neoplastic tissue, as estimated by the expression of the S-phase-specific histone H3 gene. In the other 56%, c-myc overexpression did not entirely depend on the proliferative activity of the neoplastic population. In this latter group, c-myc deregulation did not reside in structural modifications of the putative regulatory regions of the gene. Therefore, c-myc overexpression, at least in a subset of colorectal cancer, seems to be consequent to alterations in transregulative phenomena exerted on the c-myc gene by other genetic loci.

A coordinated proto-oncogene expression characterizes MCF 247 murine leukemia virus-induced T-cell lymphomas irrespectively of proviral insertion affecting myc loci

Proto-oncogene transcriptional activation was analyzed in a group of MCF 247 MuLv-induced T-cell lymphomas to identify transformation-specific gene activations and determine whether the proviral insertion near a myc gene could promote a peculiar mechanism of transformation through a differential proto-oncogene expression pattern. Of the six lymphomas analyzed, three showed the MCF 247 provirus integrated within the N-myc locus, one carried the provirus integrated near c-myc, whereas for the remaining two, no evidence of proviral integrations in any of the known myc loci was obtained. Independently of the integrative events, the pattern of proto-oncogene expression was almost identical in all six lymphomas. These findings seem to rule out the existence of a peculiar pathway of transformation associated with the proviral insertion near a myc locus. Moreover, the transcription pattern observed was qualitatively identical to that displayed by normal thymocytes; only quantitative differences in c- or N-myc, c-myb and Ha-ras were observed. These results suggest that the T-cell proto-oncogene activation program is not qualitatively affected by the transforming event(s).

N-myc activation by proviral insertion in MCF 247-induced murine T-cell lymphomas

N-myc proto-oncogene rearrangement was found in three out of six AKR murine T-cell lymphomas induced by the highly oncogenic MCF 247 MuLV. Molecular analyses showed that structural modification of the proto-oncogene in all three lymphomas was in the consequence of MCF 247 proviral integration within the gene III exon. All integrated proviruses have the same transcriptional orientation as the N-myc gene. As a consequence of proviral insertion, the N-myc gene becomes transcriptionally active, producing an abnormal mRNA. These findings suggest a possible causative role of such an integrative event in murine T-cell lymphomagenesis.

In K562 leukemia cells treated with doxorubicin and hemin, a decrease in c-myc mRNA expression correlates with loss of self-renewal capability but not with erythroid differentiation

The decrease in c-myc mRNA expression occurring in leukemia cell lines induced to differentiate is supposed to be an early event of the commitment to the differentiation program. Alternatively, the decrease in c-myc mRNA expression could be simply a consequence of loss of the self-renewal capability characteristic of the terminal differentiated phenotypes. In an attempt to clarify these hypotheses, we analysed comparatively the kinetics of variations in c-myc mRNA expression, hemoglobin synthesis, DNA and RNA syntheses, cell cycle kinetics and self-renewal capability in normal and hemin-treated K562 leukemia cells exposed for different periods of time to the antitumoral antibiotic doxorubicin. Times of exposure to doxorubicin were either 2 h, which resulted in reversible induction of hemoglobin synthesis without significant cytostatic effects, or continuously for more than 5 days, which resulted in an irreversible induction of hemoglobin synthesis and in the complete and irreversible loss of self-renewal activity. Comparative analysis of the experimental data indicated that the decrease in c-myc mRNA expression correlated with the loss of replicative activity, possibly due to an irreversible cytostatic effect of the long exposure to doxorubicin, but not with the commitment to the differentiation programs.

Activation by Point Mutation of Ki-ras Gene Occurring in Transfected Human Normal dna

A mutation-activated human Ki-ras gene was detected in NIH 3T3 cells transfected with high molecular weight DNA extracted from peripheral blood leukocytes of a healthy blood donor. A deoxyguanosine at position 35 of the first exon was substituted by deoxythymidine. Nevertheless, cloning and sequencing of seven independent Ki-ras first exons, isolated from the same human genomic DNA used to transfect NIH 3T3 cells, failed to reveal the expected point mutation. Since transfected DNA is susceptible to mutagenesis in mammalian cells, we hypothesize that a base substitution occurred during the transfection assay.