HIF-1 inactivation empowers HIF-2 to drive hypoxia adaptation in aggressive forms of medulloblastoma

Medulloblastoma (MB) is the most prevalent brain cancer in children. Four subgroups of MB have been identified; of these, Group 3 is the most metastatic. Its genetics and biology remain less clear than the other groups, and it has a poor prognosis and few effective treatments available. Tumor hypoxia and the resulting metabolism are known to be important in the growth and survival of tumors but, to date, have been only minimally explored in MB. Here we show that Group 3 MB tumors do not depend on the canonical transcription factor hypoxia-inducible factor-1α (HIF-1α) to mount an adaptive response to hypoxia. We discovered that HIF-1α is rendered inactive either through post-translational methylation, preventing its nuclear localization specifically in Group 3 MB, or by a low expression that prevents modulation of HIF-target genes. Strikingly, we found that HIF-2 takes over the role of HIF-1 in the nucleus and promotes the activation of hypoxia-dependent anabolic pathways. The exclusion of HIF-1 from the nucleus in Group 3 MB cells enhances the reliance on HIF-2's transcriptional role, making it a viable target for potential anticancer strategies. By combining pharmacological inhibition of HIF-2α with the use of metformin, a mitochondrial complex I inhibitor to block respiration, we effectively induced Group 3 MB cell death, surpassing the effectiveness observed in Non-Group 3 MB cells. Overall, the unique dependence of MB cells, but not normal cells, on HIF-2-mediated anabolic metabolism presents an appealing therapeutic opportunity for treating Group 3 MB patients with minimal toxicity.

Molecular follow-up of first-line treatment by osimertinib in lung cancer: Importance of using appropriate tools for detecting EGFR resistance mutation C797S

The C797S mutation encoded by EGFR exon 20 is classically observed as a tertiary event in EGFR-mutant non-small-cell lung carcinoma (NSCLC) primarily treated by first generation tyrosine kinase inhibitors (TKI) and secondarily treated by third-generation TKI, such as osimertinib, if the EGFR-T790M resistance mutation is detected. Recently, significant prolonged progression free survival has been observed following first-line osimertinib, in EGFR-mutant NSLC. While mechanisms of molecular resistance to first-generation TKI have been well studied, little is known about resistance induced by primary third-generation TKI treatments. We report the case of a 65 year-old female treated by first-line osimertinib for a multimetastatic exon 19-EGFR-mutant NSCLC. EGFR-C797S resistance mutation and PIK3CA mutation were detected together with the remaining EGFR-exon 19 deletion. This observation provides insights of acquired resistance to first line-osimertinib. It also highlights the importance of making molecular platforms which perform routine EGFR testing in lung cancer aware of the kind of therapeutic protocols given to the patient. Indeed, for rapid results or low-costs procedures, some targeted methods specifically targeting T790M may be used at relapse and may overlook alterations such as C797S or PIK3CA mutations. Targeted next generation sequencing is therefore a recommended option.

MET immunolabelling is a useful predictive tool for MET gene amplification in glioblastoma

AIMS

MET gene amplification is rare in glioblastoma (GBM) and represents a potential target for MET inhibitors. An immunohistochemical screening may be useful to identify MET amplification. The aim of our study was to establish how MET immunolabelling correlates with MET amplification.

METHODS

Three cohorts including 108 GBM (cohort 1, prospective), 104 GBM (cohort 2, retrospective) and 52 GBM (cohort 3, prospective) were investigated for MET expression by immunohistochemistry. MET amplification was assessed by comparative genomic hybridization on microarray (CGH-array) in all cohorts and by fluorescent in situ hybridization (FISH) in cohorts 2 and 3. Active form of MET was assessed using p-MET (Y1349) immunohistochemistry.

RESULTS

Diffuse MET amplification detectable by CGH-array was associated with diffuse, strong MET immunolabelling (four cases in cohort 1 and one case in cohort 2). Focal MET amplification detectable only by FISH was observed in small foci of strongly immunopositive cells in two GBM (cohort 2). In both cohorts, MET amplification was never detected in GBM devoid of strongly immunopositive cells. MET overexpression, observed in 23% of unamplified GBM, was associated with a predominant weak-to-moderate staining intensity and with necrosis (P < 0.005). p-MET was detected in all MET-amplified GBM and in perinecrotic areas of nonamplified GBM. A strong MET immunostaining intensity, at least focal and distant from necrosis, showed 100% sensitivity and 84% specificity for predicting MET amplification in cohort 3.

CONCLUSIONS

MET amplification is characterized by strongly immunopositive cells. Only GBM showing strong MET immunostaining is appropriate for the assessment of MET amplification.

Self-renewal gene tracking to identify tumour-initiating cells associated with metastatic potential

Tumour-initiating cells (TICs) are rare cancer cells isolated from tumours of different origins including high-grade tumours that sustain neoplasic progression and development of metastatic disease. They harbour deregulated stem cells pathways and exhibit an unchecked ability to self-renew, a property essential for tumour progression. Among the essential factors maintaining embryonic stem (ES) cells properties, OCT-4 (also known as POU5F1) has been detected in tumours of different origins. Although ectopic expression results in dysplasic growth restricted to epithelial tissues, overexpression expands the proportion of immature cells in teratomas. However, OCT-4-expressing cells have not been purified from spontaneously occurring tumours, thus information concerning their properties is rather scant. Here, using p53-/- mice expressing green fluorescent protein and the puromycin resistance gene under the control of the Oct-4 promoter, we show that OCT-4 is expressed in 5% onwards of the undifferentiated tumour cell populations derived from different organs. OCT-4 expression was low as compared with ES cells, but was associated with a 'stemness' signature and expression of the chemokine receptor CXCR4. These cells displayed cancer stem cell features, including increased self-renewal and differentiation ability in vitro and in vivo. They not only formed allografts containing immature bone regions but also disseminated into different organs, including lung, liver and bone. Experiments based on RNA interference revealed that Oct-4 expression drives both their engraftment and metastasis formation. This work points out the crucial contribution of Oct-4-expressing TICs in the hierarchical organization of the malignant potential, leading to metastasis formation. Consequently, it provides an appropriate model to develop novel therapies aiming to strike down TICs by targeting self-renewal genes, therefore efficient to reduce tumour growth and metastatic disease.

Liposarcoma or lipoma: does genetics change classic imaging criteria?

Differentiating benign from malignant fatty tumours has always been very difficult for both radiologists and pathologists. Cytogenetic and molecular genetic analyses provide complementary tools for differentiating soft tissue tumours. Our objective was to compare imaging criteria of malignancy with a new diagnostic gold standard, namely, pathological analysis combined with cytogenetic and molecular genetic analyses. Nineteen patients with a fatty tumour were included. All had computed tomography and/or magnetic resonance imaging examination before any biopsy or surgery. All had histopathological and cytogenetic and/or molecular genetic analyses. The imaging diagnosis of benign or malignant lesions was accurate in 15 cases, with 4 false positives for malignancy. Erroneous criteria were a large size (4 cases), and a mass that was not purely fatty. In conclusion, the main pitfall for a false positive radiological diagnosis of liposarcoma is certainly a large-sized tumour. Cytogenetic and molecular genetic analyses contribute to the diagnosis and can be performed at the same time with a core biopsy.

Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: Results of a multicentric phase II study on 25 patients

10032

The treatment of dermatofibrosarcoma protuberans (DFSP) relies on a wide local excision with frequent need of reconstructive surgery. A (17,22)translocation with Co1A1-PDGF fusion is present in > 90 % of the cases. Some patient's observations and a report on 9 patients suggest that Imatinib mesylate (IM), targeting PDGFRβ, has a clinical interest in DFSP. The primary aim of this phase II multicentric study was to define the percentage of clinical responders (RECIST) to a preoperative 2 months 600mg IM daily before wide local excision. The secondary goals were to determine tolerance, imaging (ultrasound and MRI), pathological responses and to analyse PDGFRβ phosphorylation status and tumour cell apoptosis in sequential tissues specimen. A flexible design with interim analysis after recruitment of 6 patients was used. 18 to 28 patients had to be enrolled to detect a 30% clinical response rate (relative decrease of tumor of at least 30%) with power 80%, using a one-sided test against 5%, at the 2.5% one-sided level. The interim analysis yielded a clinical response in 3 of 6 patients without severe adverse event. An independent committee advised to continue the trial to obtain a total number of at least 24 patients, in order to reduce the confidence interval of response rate. Twenty-five adults suffering from primary or recurrent DFSP have been included from July 2004 to May 2006, 13F and 12 M, median age 42.4 years [range 23.0–72.5]. Tumour characteristics were as follows: primary (n=20), recurrence (n=5) involving trunk(n=14), head or neck (n=3), limbs (n=6), other n=2; median size was 4.5cm [range 2.4–16]. Translocation t(17;22) was detected in 12 of 12 informative tumours following caryotype or FISH analysis. A clinical response was achieved in 9 (36%) patients(95%CI 18.9–57.5). The median relative decrease of tumor was of 20.0% [range -12.5;100]. Apart from expected grade 1 or 2 side effects, we observed 1 grade 3 neutropenia, 1 grade 3 maculopapular rash and 1 grade 4 transient transaminitis. Imatinib has been recently approved for the treatment of unresectable or metastatic dermatofibrosarcoma. Our results should prompt us to analyse the clinical benefit of a longer duration neoadjuvant treatment for patients with DFSPin order to reduce surgical margins

[Table: see text]

[Childhood-onset multifocal atrophic dermatofibrosarcoma]

BACKGROUND

Atrophic dermatofibrosarcoma is a rare clinical variant of dermatofibrosarcoma protuberans (or Darier-Ferrand tumor) preferentially observed in childhood and early adulthood.

OBSERVATION

We report a case of multifocal atrophic dermatofibrosarcoma protuberans of childhood onset only diagnosed when the patient was 29 years old. The clinical presentation was an asymptomatic macular brown plaque on the right thigh measuring 10 cm. Initially, because of the large size of the lesion, treatment consisted of limited surgical excision.

DISCUSSION

Diagnosis of the atrophic variant of dermatofibrosarcoma in childhood is difficult, and is usually made several years later in early adulthood because of its slow development, lack of symptoms and generally benign appearance. Histological tests and immunohistochemical staining may confirm clinically suspected diagnosis, and in complex cases, cytogenetic studies can help confirm a diagnosis of dermatofibrosarcoma through detection of reciprocal translocation t (17,22), which fuses collagen type Ialpha1 (COLIA1) and platelet-derived growth factor (PDGDFbeta), and which is highly characteristic of dermatofibrosarcoma protuberans. Conventional treatment of dermatofibrosarcoma protuberans consists of extensive surgical excision, but Mohs micrographic surgery is also advocated for removal of certain dermatofibrosarcoma protuberans, while use of tyrosine kinase PDGF receptor inhibitors such as imatinib mesylate (Glivec) is limited to distant metastases.

Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: Preliminary results of a multicentric phase II study

9550

Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma of intermediate malignant potential. Treatment relies on a wide local excision with negative margin with frequent need of reconstructive surgery. A translocation between chromosomes 17 and 22 that places PDGFB under the control of the collagen 1A1 promoter is present in > 90% of the cases leading to an up regulation of PDGFB expression and activation of the tyrosinase kinase PDGFRβ. Anecdotal reports and a report on 8 patients suggest that Imatinib mesylate (IM) has a clinical interest in DFSP. The primary aim of this phase II multicentric study is to define the percentage of clinical responders (RECIST) to a preoperative 2 months 600mg IM daily before wide local excision. The secondary goals are to determine tolerance, imaging (ultrasound and MRI), pathological responses and to analyse PDGFRβ phosphorylation status and tumour cell apoptosis in sequential tissues specimen. Fifteen adults suffering from primary or recurrent DFSP have been included since July 2004. All tumors had a diameter ≥2cm. A flexible design with interim analysis after recruitment of 6 patients was used. 18 to 28 patients had to be enrolled to detect a 30% response rate with power 80%, using a one-sided test against 5%, at the 2.5% level. Three men and 3 women, median age 48.4 years [23; 72.5] have been evaluated. Tumour characteristics are as follows : primary (n=4), recurrence (n=2) all involved trunk, median size 5.75cm [2.5–12]. Tolerance was good apart from grade 1 facial oedema (n=6) grade 2 maculopapular rash (n=1), grade 1 asthenia (n=1), grade 1 pyrosis (n=2). Translocation t(17;22) was detected in all tumours. A partial response was achieved in 3 of 6 patients. The median relative decrease of tumor in the PR and non responder patients was of 21.9% [−3.3; 72.0]. Histological analysis revealed a global decrease of cellularity often accompanied with a CD34 loss of expression, a fibrosis and mild peripheral lymphoid infiltrates. No evidence of apoptosis on tissue specimen after surgery was observed using TUNEL. These encouraging interim results weresubmitted to an independent committee who allowed to continue the trial and to include a total of 24 patients in order to reduce the confidence interval of response rate.

[Table: see text]

Comparison of the epidermal growth factor receptor gene and protein in primary non-small-cell-lung cancer and metastatic sites: implications for treatment with EGFR-inhibitors

BACKGROUND

Very recent studies have suggested that EGFR gene copy number and expression obtained by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) should be used to predict which lung cancer patients are expected to respond to anti-EGFR treatments. However, it is still not known whether EGFR expression differs in metastases compared to primary non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

EGFR status was analysed by IHC and FISH on tumor samples of primary NSCLC and at least one distant metastatic lesion in 30 patients.

RESULTS

Ten cases (33.3%) showed primary tumor/metastasis discordance by IHC analysis (n = 30): in seven cases, EGFR was expressed in the primary tumor but not in the metastasis, while three samples showed EGFR expression in the metastasis but not in the primary tumor (Pearson correlation coefficient = 0.331, P = 0.0074). By FISH (n = 26), seven (27%) cases were discordant: six cases showed a high-level of EGFR polysomy in the primary tumor but not in the metastasis and one case showed a high-level of EGFR polysomy in the metastasis but not in the primary sample (Pearson correlation coefficient = 0.52, P = 0.007).

CONCLUSION

EGFR expression is not stable during metastatic progression in a significant proportion of NSCLC. These findings have to be considered in future prospective studies.

Evaluation ofMDM2 andCDK4 amplification by real-time PCR on paraffin wax-embedded material: a potential tool for the diagnosis of atypical lipomatous tumours/well-differentiated liposarcomas

Atypical lipomatous tumours/well-differentiated liposarcomas and dedifferentiated liposarcomas are characterized by 12q13-15 region amplification. In contrast, this molecular event has not been reported in benign lipomas. Within the 12q13-15 chromosomal region, the MDM2, SAS, HMGA2, and CDK4 genes are the most frequent targets of amplification. A series of lipomas (36 cases) and liposarcomas (48 cases) was analysed for MDM2 and CDK4 gene amplification by real-time PCR. MDM2 and CDK4 gene amplification was detected in 2.8% and 5.6% of lipomas and 98.2% and 82.4% of liposarcomas, respectively. Moreover, co-amplification of the two genes as well as a higher-level amplification was observed more frequently in dedifferentiated liposarcomas than in atypical lipomatous tumours/well-differentiated liposarcomas. Real-time PCR proved to be a fast and reliable method to characterize lipomas and liposarcomas by quantification of MDM2 and CDK4 gene amplification. It is applicable to paraffin wax-embedded tissues and could be useful when histological diagnosis is difficult.

Infiltrating intramuscular lipoma of the temporal muscle. A case report with molecular cytogenetic analysis

Intramuscular lipomas are uncommon benign mesenchymal tumors which infiltrate skeletal muscle and are exceedingly rare in the head and neck region. Because of the infiltrating nature of the lesion and a high propensity for recurrence, they are sometimes difficult to distinguish from well-differentiated liposarcomas (WDLS). We report, the first case of an infiltrating lipoma of the temporal muscle in a 62-year-old white man who presented with a slow growing mass in the left temporal region. The histopathological examination showed diffuse infiltration of the striated muscle fibers by mature adipocytes. There were no lipoblasts or cells with atypical nuclei as described in WDLS. We performed interphase fluorescence in situ hybridization (FISH) analyses using painting probes for chromosome 12 and a specific probe for the MDM2 gene and comparative genomic hybridization. The results did not identify MDM2 or 12q amplification and therefore confirmed the benign nature of the lesion.

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

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

[Spindle cell lipoma and 13q deletion: diagnostic utility of cytogenetic analysis]

AIM

Spindle cell lipomas are rare adipose tissues tumors. Histologically, these lesions are composed of mature adipocytes and spindle cells associated with collagen bundles. Spindle cell lipomas are benign tumors that can be difficult to distinguish from malignant tumors such as spindle cell liposarcomas, myxoid liposarcomas or well-differentiated liposarcomas.

RESULTS

We report herein the description of two new cases. The first case was a deeply situated and infiltrating tumor located in the retromastoidian area. The karyotype showed the presence of two chromosomal abnormalities, a partial deletion of the long arm of chromosome 13, del(13)(q12) and a balanced reciprocal translocation t(2;6)(p16~21;p21). The second case was a subcutaneous tumor of posterior cervical localization. The karyotype showed a 13q deletion associated with a complex rearrangement of chromosomes 5, 6 and 10. The presence of the 13q deletion allowed us to confirm the diagnosis of spindle cell lipoma in both cases. This deletion has been previously described in six out the eleven published karyotype reports. The 13q deletion is usually associated with partial monosomy 16. The present case confirms that it can occur independently. The 6p21 rearrangement may also play a role in the pathobiology of this tumor, as suggested by the positive HMGIY expression detected by immunohistochemistry.

CONCLUSION

Our study further illustrates that spindle cell lipomas can infiltrate the surrounding muscle and emphasizes the usefulness of cytogenetic analysis in the differential diagnosis of soft tissue tumors.

Ectopic sequences from truncated HMGIC in liposarcomas are derived from various amplified chromosomal regions

The HMGIC gene codes for an architectural transcription factor frequently rearranged by translocation in lipomas and other benign mesenchymal tumors. In sarcomas, malignant tumors of mesenchymal origin, the gene is also found to be rearranged, but in addition amplified and overexpressed. Here we report the sequence, chromosomal localization, and expression patterns of 11 novel ectopic sequences fused to exons 2 and 3 of HMGIC in seven different sarcoma samples. In addition, we identified a number of variant transcripts observed previously in benign tumors. Consistent with the suggested role of HMGIC in adipocytic differentiation, most of the novel ectopic sequences were observed in well-differentiated liposarcomas. These tumors are known to have complex marker chromosomes containing amplified segments from several chromosomes. Five novel sequences were derived from 12q14-q15, where HMGIC resides, two from 1q24, a region frequently amplified in these types of tumors, two from 11q14, and one from chromosome 2. All except one of the aberrant transcripts encoded truncated proteins with intact DNA-binding domains (AT hooks) but lacking the C-terminal acidic region, a target for constitutive phosphorylation by protein kinase CK2. Some of the ectopic sequences were transcribed in other tissues, and most of the ectopic sequences also showed recurrent amplification in liposarcomas.

ALK probe rearrangement in a t(2;11;2)(p23;p15;q31) translocation found in a prenatal myofibroblastic fibrous lesion: toward a molecular definition of an inflammatory myofibroblastic tumor family?

A prenatal tumor located in the lumbar paravertebral area was discovered during a routine ultrasound examination at 32 weeks of pregnancy and surgically removed at 4 months of life. The histopathological diagnosis was first suggested to be an infantile desmoid fibromatosis. The tumor karyotype showed a three-way translocation involving both chromosomes 2 and a chromosome 11, t(2;11;2)(p23;p15;q31). Fluorescence in situ hybridization with a probe flanking the ALK gene at 2p23 demonstrated a rearrangement, as previously described in inflammatory myofibroblastic tumors (IMTs). In light of the genetic analysis, the histopathological diagnosis was revised to IMT, although inflammatory cells were scarce. IMTs are pseudosarcomatous inflammatory lesions that primarily occur in the soft tissue and viscera of children and young adults. Our report describes for the first time the occurrence of IMT during prenatal life. The ALK rearrangement may represent the molecular definition of a subgroup of mesenchymal tumors, not always with complete morphological features of IMT, similar to the model of EWS rearrangement in the Ewing sarcoma family of tumors.

Characterization of centromere alterations in liposarcomas

Supernumerary ring and large marker chromosomes are a characteristic of atypical lipomas and well-differentiated liposarcomas (ALP-WDLPS) and are composed of amplified 12q14-15 sequences in association with variable segments from other chromosomes. Although stably transmitted, these chromosomes contain centromeric alterations, showing no detectable alpha-satellite sequences. We performed C-banding, fluorescence in situ hybridization, and immunostaining with anti-centromere antibodies in 8 cases of liposarcomas with supernumerary rings and large markers, including 5 ALP-WDLPS and 3 dedifferentiated-LPS and high-grade LPS. Our results with alpha-satellite probes and anti-CENPB antibodies confirm the lack of detectable alpha-satellite sequences in the five ALP-WDLPS supernumerary chromosomes, whereas centromeric activity was proved by the detection of kinetochores by using anti-CENPC antibodies. In contrast, the high grade and dedifferentiated liposarcomas showed a different pattern. In 2 cases, amplified chromosome 12 sequences, including amplification of alpha-satellite 12 sequences in 1 case, were present on chromosomes with typical centromeres. In another case, the rings were similar to WDLPS-ALP rings, but a large marker contained a chromosome 5 centromere and amplified alpha-satellite sequences from chromosome 8. ALP-WDLPS is the first example of a tumor class for which the presence of stable analphoid chromosomes is a constant and specific abnormality. Formation of newly derived centromeres, so-called neocentromeres, could be an original and effective way to maintain a selective advantage in neoplastic cells by conferring stability to the supernumerary chromosomes of ALP-WDLPS. The activation of normally non-centromeric sequences might be obtained by an epigenetic mechanism due to the peculiar chromatin conformation of these highly complex chromosomes.

Dysregulation of HMGIC in a uterine lipoleiomyoma with a complex rearrangement including chromosomes 7, 12, and 14

Uterine lipoleiomyomas are extremely rare tumors consisting of a mixture of mature adipocytes and smooth muscle cells. Using G-banding and FISH, we characterized a complex rearrangement involving chromosomes 7, 8, 10, 11, 12, and 14 in one of these tumors. The region 14q23-24 was inserted into the long arm of the derivative chromosome 12, between the 3' end of HMGIC and 7q21-22, another region often rearranged in uterine leiomyomas. Other portions of chromosomes 12 and 14 were involved in derivative chromosomes 7, 11, 12, and 14. A chromosome 8 was involved in a three-way rearrangement including the derivative 7, a ring chromosome 10, and a small derivative chromosome 8 bearing segments of chromosomes 10 and 11. No abnormality of chromosome 5 was detected, in contrast to two previously reported cytogenetic analyses of uterine lipoleiomyoma. The consistent finding of chromosomes 12 and 14 on different derivatives indicates that the t(12;14) was a primary event. In addition, immunohistochemical studies showed that HMGI-C was aberrantly expressed in this tumor. These observations suggest that uterine lipoleiomyomas have a pathogenetic origin similar to that of typical leiomyomas. Genes Chromosomes Cancer 27:209-215, 2000.

The C1orf9 gene encodes a putative transmembrane member of a novel protein family

Here we report the characterization of a human mRNA encoding a novel protein denoted C1orf9 (chromosome 1 open reading frame 9). The cDNA sequence, derived from a testis cDNA library, contains 5700 bp which encodes an open reading frame of 1254 amino acids. The deduced protein contains a putative N-terminal signal peptide and one putative transmembrane region, indicating membrane localization. No significant homology was found with known characterized proteins. However, a 150 amino acid region has significant homology to deduced protein sequences from other organisms, including Caenorhabditis elegans (43% identity), Saccharomyces cerevisiae (47% identity), Schizosaccharomyces pombe (48% identity), and two proteins from Arabidopsis thaliana (42% and 40% identity), suggesting a novel family of conserved domains. The C1orf9 gene was assigned to chromosome 1q24. The gene spans approximately 78.7 kb and is organized into at least 24 exons. Expression analysis revealed a single C1orf9 mRNA species of approximately 6.0 kb with a predominant expression in pancreas and testis, and only low levels of expression in other tissues examined.

[Genetics of uterine leiomyomata]

Uterine leiomyomata, or fibroids, represent the most common tumor in women of reproductive age. Although benign, leiomyomata constitute a major health problem, and are the most frequent indication for hysterectomy. The pathobiology of these tumors is still poorly understood. Cytogenetic and genetic studies have, in recent years, advanced our understanding of the etiology of these tumors. Specifically, cytogenetic aberrations involving chromosomes 6, 7, 12 and 14 have been shown to constitute the major chromosomal abnormalities seen in leiomyomata and have led to the discovery that HMGIC and HMGIY, two members of the non-histone high mobility group of genes, are involved in fibroid development. HMGIC and HMGIY map to 12q15 and 6p21, and their disruption or dysregulation has been shown to contribute to leiomyomata formation. Given the observation of several additional, but consistent, chromosomal aberrations, it is likely that other genes with fundamental roles in the pathobiology of uterine leiomyomata await identification. Furthermore, twin studies and the discovery of both ethnic and familial predispositions have suggested a genetic liability to develop uterine leiomyomata.

Identification and characterization of TESK2, a novel member of the LIMK/TESK family of protein kinases, predominantly expressed in testis

In this study we present the cDNA sequence of a novel putative protein kinase, denoted TESK2. The open reading frame of TESK2 encodes a putative 555-amino-acid protein, including a protein kinase consensus sequence in the N-terminal half. The protein kinase domain of TESK2 is structurally similar to the kinase domain of the protein serine/threonine kinase TESK1 (64% identity) and to those of the LIMK1 and LIMK2 kinases (42 and 39% identity, respectively). TESK2, together with TESK1, constitutes a second subgroup of the LIMK/TESK family of protein kinases, as revealed by phylogenetic analysis of the protein kinase domains. Chromosomal localization of human TESK2 was assigned to 1p32. Expression analysis of human TESK2 revealed a single mRNA species of 3.0 kb predominantly expressed in testis and prostate and low expression in most other tissues examined. Rat testicles expressed a single species of TESK2 mRNA of approximately 3.5 kb. However, the transcript was first detectable in rat testis after day 30 of postnatal development and was predominantly expressed in round spermatids. These observations suggest that TESK2 plays an important role in spermatogenesis.

Expression of HMGIY in three uterine leiomyomata with complex rearrangements of chromosome 6

Uterine leiomyomata (UL) are a major public health problem, yet little is known about their etiology. Genetic factors likely influence UL development and growth; for example, approximately 40% of UL have chromosomal abnormalities detectable by conventional cytogenetic analysis, including t(12;14)(q15;q23-24), rearrangements involving the short arm of chromosome 6 and interstitial deletions of the long arm of chromosome 7. Two high-mobility group (HMG) protein genes, HMGIC and HMGIY, located at 12q15 and 6p21.3, respectively, are involved in rearrangements in various mesenchymal tumors including UL. In this study, we investigated HMGIY expression in three UL with complex cytogenetic rearrangements of 6p21.3 by reverse transcriptase-polymerase chain reaction (RT-PCR) and electrophoretic shift assay (EMSA). Our findings suggest that there are multiple mechanisms for HMGIY dysregulation, which may include post-translational modification of the hmgiy protein and dysregulation due to different translocation partners. Furthermore, the mechanism dysregulating HMGIY in UL with 6p21.3 and 14q23-24 rearrangements may be similar to the mechanism dysregulating HMGIC in UL characterized as t(12;14)(q15;q23-24), because of the common involvement of an HMG gene and a gene at 14q23-24.

Structure of the supernumerary ring and giant rod chromosomes in adipose tissue tumors

Supernumerary ring or giant rod marker chromosomes are a characteristic of well-differentiated liposarcomas (WDLPS) and atypical lipomas (ALP) and are often observed as the sole cytogenetic abnormality, but are rare in lipomas. Using a combination of different methods, we extensively investigated the structure and composition of rings and giant rods in a series of 17 WDLPS-ALP samples and three intra- or intermuscular lipomas (IMLP), revealing a unique combination of particular features strikingly related to these tumors. Although the rings and rods displayed in vitro and in vivo stability, the presence of alpha-satellites could not be detected on these supernumerary structures. Comparative genomic hybridization analysis, in combination with fluorescence in situ hybridization, identified the chromosomal regions contributing to the formation of these chromosomes: in WDLPS-ALP, all carried amplifications of 12q 14-15 and the MDM2 gene, with variable other noncontiguous regions. In the three IMLP, the rings consistently carried amplifications of 12q15-21 and 1q21, but increased copies of MDM2 were found in only one case. Other genes located more proximal in 12q14-15 were amplified in several WDLPS-ALP, but showed a normal copy number in IMLP. Furthermore, the immunohistochemical expression of the MDM2 protein was detected in most (12/14) WDLPS-ALP, in 1-30% of the cells, but never in IMLP. These supernumerary chromosomes represent a peculiar kind of amplification structure, midway between double minute chromosomes and homogeneously staining regions, but the mechanisms underlying the formation of these structures remain obscure.

Localization and expression of the human estrogen receptor beta gene in uterine leiomyomata

Estrogens have an important function in the natural history of uterine leiomyomata. The human estrogen receptor beta gene (ESR2) has been identified recently and mapped to 14q22-24, a region frequently rearranged in uterine leiomyomata and other benign tumors, including pulmonary chondroid hamartomas and endometrial polyps. Using fluorescence in situ hybridization and radiation hybrid mapping, we map ESR2 within 14q23-24.1, to a region approximately 2 Mb centromeric to the t(12;14) breakpoint in uterine leiomyomata, between markers D14S63 and WI-7536. Two YAC clones, 948B6 and 741H4, contain ESR2. Using RT-PCR, we show that ESR2 is expressed in uterine leiomyomata and pulmonary chondroid hamartomas as well as in normal myometrium. Lack of a direct relationship between rearrangement of 14q23-24 and ESR2 expression suggests that ESR2 is not involved with HMGIC or HMGIY in t(12;14) or t(6;14). However, because of its relatively close physical distance from the characteristic site of rearrangements in 14q23-24, a role for ESR2 in the pathobiology of these tumors warrants future consideration.

[Jacobsen's syndrome, thrombopenia and humoral immunodeficiency]

BACKGROUND

Clinical features of Jacobsen syndrome include facial dysmorphism, congenital heart defects, digit anomalies and mild to moderate psychomotor retardation. Thrombocytopenia or pancytopenia is observed in one half of patients.

PATIENTS

Two unrelated children, a 6-month- and a 12-year-old, presented with a moderate thrombocytopenia associated with the clinical features of Jacobsen syndrome. Bone marrow aspirates showed, in both patients, normal cellularity with an increased number of micromegacaryocytes. Chromosome analysis showed a partial deletion of the long arm of chromosome 11. The 12-year-old patient had a history of upper respiratory airways infections with immune humoral deficiency (decreased level of IgA and IgM) which, to our knowledge, has never been reported.

CONCLUSION

Jacobsen syndrome is a cause of inherited thrombocytopenia in children. Humoral immune functions must be explored in patients with a history of repeated infections.

Cloning, chromosal mapping, and tissue expression of the gene encoding the human Eph-family kinase ligand ephrin-A2

The Eph-related receptor tyrosine kinases constitute a large family of receptors with most members displaying specific expression patterns in the developing embryo. Ligands for Eph receptor tyrosine kinases, recently renamed ephrins, comprise a family of at least 8 membrane-bound members that display promiscuous binding to Eph receptors. Here we report the characterization of a human cDNA clone with high homology to the gene encoding the murine ephrin-A2 ligand. The human gene encodes a single 2.4-kb mRNA with a restricted and developmentally-regulated tissue distribution pattern. In the fetus, ephrin-A2 mRNA is expressed in brain and intestine, whereas in the adult, high levels of ephrin-A2 mRNA are detectable in lung and intestine. Using PCR-based screening of genomic DNA from human x rodent hybrid cell lines, the gene encoding ephrin-A2 (EFNA2) was assigned to chromosome 19. Fluorescence in situ hybridization to metaphase chromosome preparations refined this localization to band p13.3.

COL1A1-PDGFB fusion in a ring chromosome 4 found in a dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DP), an infiltrative skin tumor of intermediate malignancy, presents specific cytogenetic features such as reciprocal translocations t(17;22)(q22;q13.1) or, more often, supernumerary ring chromosomes derived from t(17;22). Different translocations, including t(2;17) and t(X;7), have also been described. We have shown previously that both r(17;22) and t(17;22) present the same molecular rearrangement fusing the COL1A1 gene on chromosome 17 and the PDGFB gene on chromosome 22. Out of our series of 16 DPs, we detected an extra ring chromosome in tumor T96-1175, which juxtaposed sequences from chromosomes 4 and 17. As shown by fluorescence in situ hybridization (FISH) using chromosome painting and alpha-satellite probes, T96-1175 apparently lacked chromosome 22 material in the ring. However, involvement of chromosome 22 through a rearrangement of PDGFB was shown by Southern blotting, reverse transcriptase-polymerase chain reaction (RT-PCR), and FISH. This study demonstrates that a cryptic molecular rearrangement between chromosomes 17 and 22 occurred in addition to the recombination of chromosomes 4 and 17 initially identified by FISH. Assessment for cryptic molecular events should be performed in other variant DP rearrangements.

Molecular cloning of a T cell-specific adapter protein (TSAd) containing an Src homology (SH) 2 domain and putative SH3 and phosphotyrosine binding sites

Adapter proteins link catalytic signaling proteins to cell surface receptors or downstream effector proteins. In this paper, we present the cDNA sequence F2771, isolated from an activated CD8+ T cell cDNA library. The F2771 cDNA encodes a novel putative adapter protein. The predicted amino acid sequence includes an SH2 domain as well as putative SH3 and phosphotyrosine binding interaction motifs, but lacks any known catalytic domains. The expression of the gene is limited to tissues of the immune system and, in particular, activated T cells. The protein expressed by F2771 cDNA in transfected COS cells is localized in the cytoplasm. A polyclonal antiserum raised against an F2771-encoded peptide reacts with a tyrosine-phosphorylated 52-kDa protein expressed in phytohemagglutinin-stimulated peripheral blood mononuclear cells. The gene is localized to chromosome 1q21, a region often found to be aberrant in lymphomas. The T cell-specific expression and the rapid induction of mRNA expression upon receptor binding, as well as the lack of catalytic domains in the presence of protein interaction domains, indicate that the F2771 gene encodes a novel T cell-specific adapter protein (TSAd) involved in the control of T cell activation.

Identification of new translocation breakpoints at 12q13 in lipomas

Cytogenetic studies of banded chromosomes and fluorescence in situ hybridization (FISH) of several yeast artificial chromosomes (YACs) that are part of a 128-kb resolution physical map of a portion of 12q13 revealed that 4/14 (28%) lipomas have breakpoints in 12q13. These breakpoints are more than 10 Mb away from the HMGIC gene at 12q14-q15, which is known to be modified in some lipomas. FISH with individual YACs at 12q13 enabled us to identify four YACs that span three breakpoints. Our results suggest that genes other than HMGIC on human chromosome 12 may be involved in the etiology of lipoma development.

The melanin-concentrating hormone gene in human: flanking region analysis, fine chromosome mapping, and tissue-specific expression

Genomic sequences encoding the human melanin-concentrating hormone (MCH) were isolated from a YAC library and subcloned in pUC vector using a novel E. coli transformation method. A 4.1-kb fragment encompassing approximately 1.0 kb of the 5'-end-flanking region, the three exons-two introns of the coding region and approximately 1.7 kb of the 3'-end-flanking region, was sequenced. Comparison with the rat MCH gene indicated strong conservation in the 5'-flanking region, in particular over the putative TATA box, CAAT box, GRE and AP-1 elements that could potentially regulate MCH gene expression. FISH with a fluorescent MCH genomic probe on human chromosomes and PCR analysis of a YAC panel mapped MCH to chromosome 12q23.1 in a region flanked by D12S1074 and D12S1030 markers. Expression of the MCH RNA species and pro-MCH-derived peptides (MCH and NEI) was investigated in human tissues by combining Northern blotting, RT-PCR, in situ hybridization, immunohistochemistry and RIA. In the human brain, MCH mRNA and MCH/NEI peptides were predominantely expressed in the lateral hypothalamus in agreement with the known distribution of MCH expression in rat. In addition, MCH gene products were detected in extra-hypothalamic sites, such as the pallidum, neocortex and cerebellum. In peripheral tissues, MCH mRNA was identified in several organs, including the thymus, brown adipose tissue, duodenum and testis. An additional shorter MCH gene transcript, likely the result of alternate splicing, was revealed in several brain areas and peripheral tissues. While only fully processed MCH and NEI were found in hypothalamus, a different peptide form, bearing MCH and NEI epitopes, was detected in peripheral organs. This represents the first evidence for differential processing of pro-MCH in mammals.

Characterization, expression and chromosomal localization of a human gene homologous to the mouse Lsc oncogene, with strongest expression in hematopoetic tissues

A human cDNA clone, denoted sub1.5, was isolated from cDNA library generated from human T cells. The sub1.5 cDNA sequence was novel and was not identical to any known cDNA sequences in the GenBank. Recently, however, a mouse cDNA (Lsc) with high homology to sub1.5 was identified, indicating that the sub1.5 sequence may represent the human homologue of the mouse Lsc gene. The sub1.5 cDNA includes an open reading frame of 875 amino acids, predicting a protein with molecular weight of 97 kDa. Like Lsc, sub1.5 shows homology to the previous described oncogene Lbc, in particular to two functional domains in the Lbc protein; the Dbl proto-oncogene homology domain and the pleckstrin homology domain. Lsc is proposed to be an oncogene and is a member of a growing family of proteins that may function as activators of the Rho family GTPases. Members of the Rho family regulates the polymerization of actin to produce stress fibers. Activation of Rho GTPases by sub1.5 is also indicated by our studies, as stress fiber formation is observed in serum-starved stable NIH3T3 sub1.5 transfectants. Sub1.5 cDNA hybridizes to two major transcripts of 3.5 and 5 kb size and the strongest expression is seen in hematopoietic tissues like thymus, lymph nodes, peripheral blood leukocytes and spleen. We also show that both purified B and T cells express sub1.5. In addition, our data indicate that sub1.5 mRNA is abundantly expressed in CD34+ human progenitor cells. Fluorescent in situ hybridisation, using sub1.5 cDNA as a probe on human metaphases, shows that the sub1.5 gene is localized to chromosome 19q13.13.