The protooncogene CHOP/GADD153, involved in growth arrest and DNA damage response, is amplified in a subset of human sarcomas

Aminoacyl-tRNA synthetase - a molecular multitasker

Aminoacyl-tRNA synthetases (AaRSs) are valuable "housekeeping" enzymes that ensure the accurate transmission of genetic information in living cells, where they aminoacylated tRNA molecules with their cognate amino acid and provide substrates for protein biosynthesis. In addition to their translational or canonical function, they contribute to nontranslational/moonlighting functions, which are mediated by the presence of other domains on the proteins. This was supported by several reports which claim that AaRS has a significant role in gene transcription, apoptosis, translation, and RNA splicing regulation. Noncanonical/ nontranslational functions of AaRSs also include their roles in regulating angiogenesis, inflammation, cancer, and other major physio-pathological processes. Multiple AaRSs are also associated with a broad range of physiological and pathological processes; a few even serve as cytokines. Therefore, the multifunctional nature of AaRSs suggests their potential as viable therapeutic targets as well. Here, our discussion will encompass a range of noncanonical functions attributed to Aminoacyl-tRNA Synthetases (AaRSs), highlighting their links with a diverse array of human diseases.

Clinical utility of methionyl-tRNA synthetase 1 immunostaining in cytologic brushings of indeterminate biliary strictures: a multicenter prospective study

BACKGROUND AND AIMS

Endobiliary brushings are routinely used in the diagnosis, treatment, and prognostication of biliary strictures. However, standard Papanicolaou (Pap) staining has a low sensitivity in this setting, and the accuracy of brush cytology has not been established for indeterminate strictures. We therefore evaluated the diagnostic merit of methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence (IF) staining in such cytologic specimens.

METHODS

During ERCP, endobiliary brushings were obtained from patients with extrahepatic biliary strictures prospectively enrolled at 6 tertiary hospitals. Using liquid-based cytologic preparations of these samples, we performed Pap and MARS1 IF staining.

RESULTS

In total, 240 patients were eligible; of these, we compared the Pap and MARS1 IF staining results of 218 (malignant, 157; benign, 61). By conventional Pap staining, the diagnoses were distributed as follows: malignant, 55; suspicious of malignancy, 60; atypical, 45; negative for malignancy, 58. MARS1 IF staining was strongly positive in malignant biliary stricture but not so in specimens negative for malignancy. The diagnostic parameters (sensitivity, specificity, positive predictive value, negative predictive value, and accuracy) of the MARS1 IF (93.6%, 96.7%, 98.7%, 85.5%, and 94.5%, respectively) and conventional Pap (73.2%, 100%, 100%, 59.2%, and 80.7%, respectively) staining methods differed significantly (P < .0001).

CONCLUSIONS

The high sensitivity and accuracy of MARS1 IF staining enabled the detection of malignancy in patients with biliary strictures. Further prospective studies are needed to validate our findings. (Clinical trial registration number: NCT03708445.).

Single-Cell Transcriptomics Reveals the Complexity of the Tumor Microenvironment of Treatment-Naive Osteosarcoma

Osteosarcoma (OS), which occurs most commonly in adolescents, is associated with a high degree of malignancy and poor prognosis. In order to develop an accurate treatment for OS, a deeper understanding of its complex tumor microenvironment (TME) is required. In the present study, tissues were isolated from six patients with OS, and then subjected to single-cell RNA sequencing (scRNA-seq) using a 10× Genomics platform. Multiplex immunofluorescence staining was subsequently used to validate the subsets identified by scRNA-seq. ScRNA-seq of six patients with OS was performed prior to neoadjuvant chemotherapy, and data were obtained on 29,278 cells. A total of nine major cell types were identified, and the single-cell transcriptional map of OS was subsequently revealed. Identified osteoblastic OS cells were divided into five subsets, and the subsets of those osteoblastic OS cells with significant prognostic correlation were determined using a deconvolution algorithm. Thereby, different transcription patterns in the cellular subtypes of osteoblastic OS cells were reported, and key transcription factors associated with survival prognosis were identified. Furthermore, the regulation of osteolysis by osteoblastic OS cells via receptor activator of nuclear factor kappa-B ligand was revealed. Furthermore, the role of osteoblastic OS cells in regulating angiogenesis through vascular endothelial growth factor-A was revealed. C3_TXNIP⁺ macrophages and C5_IFIT1⁺ macrophages were found to regulate regulatory T cells and participate in CD8⁺ T cell exhaustion, illustrating the possibility of immunotherapy that could target CD8⁺ T cells and macrophages. Our findings here show that the role of C1_osteoblastic OS cells in OS is to promote osteolysis and angiogenesis, and this is associated with survival prognosis. In addition, T cell depletion is an important feature of OS. More importantly, the present study provided a valuable resource for the in-depth study of the heterogeneity of the OS TME.

Aminoacyl-tRNA synthetases and amino acid signaling

Aminoacyl-tRNA synthetases (ARSs) are a family of evolutionarily conserved housekeeping enzymes used for protein synthesis that have pivotal roles in the ligation of tRNA with their cognate amino acids. Recent advances in the structural and functional studies of ARSs have revealed many previously unknown biological functions beyond the classical catalytic roles. Sensing the sufficiency of intracellular nutrients such as amino acids, ATP, and fatty acids is a crucial aspect for every living organism, and it is closely connected to the regulation of diverse cellular physiologies. Notably, among ARSs, leucyl-tRNA synthetase 1 (LARS1) has been identified to perform specifically as a leucine sensor upstream of the amino acid-sensing pathway and thus participates in the coordinated control of protein synthesis and autophagy for cell growth. In addition to LARS1, other types of ARSs are also likely involved in the sensing and signaling of their cognate amino acids inside cells. Collectively, this review focuses on the mechanisms of ARSs interacting within amino acid signaling and proposes the possible role of ARSs as general intracellular amino acid sensors.

Inducing endoplasmic reticulum stress in cancer cells using graphene oxide-based nanoparticles

The endoplasmic reticulum is one of the vital organelles primarily involved in protein synthesis, folding, and transport and lipid biosynthesis. However, in cancer cells its functions are dysregulated leading to ER stress. ER stress is now found to be closely associated with hallmarks of cancer and has subsequently emerged as an alluring target in cancer therapy. However, specific targeting of the ER in a cancer cell milieu remains a challenge. To address this, in this report we have engineered ER-targeted self-assembled 3D spherical graphene oxide nanoparticles (ER-GO-NPs) encompassing dual ER stress inducers, doxorubicin and cisplatin. DLS, FESEM and AFM techniques revealed that the nanoparticles were spherical in shape with a sub 200 nm diameter. Confocal microscopy confirmed the specific homing of these ER-GO-NPs into the subcellular ER within 3 h. A combination of gel electrophoresis, confocal microscopy and flow cytometry studies revealed that these ER-GO-NPs induced ER stress mediated apoptosis in HeLa cells. Interestingly, the nanoparticles also activated autophagy which was inhibited through the cocktail treatment with ER-GO-NPs and chloroquine (CQ). At the same time these ER-GO-NPs were found to be efficient in prompting ER stress associated apoptosis in breast, lung and drug resistant triple negative breast cancer cell lines as well. We envision that these ER specific self-assembled graphene oxide nanoparticles can serve as a platform to exploit ER stress and its associated unfolded protein response (UPR) as a target resulting in promising therapeutic outcomes in cancer therapy.

New staining method using methionyl-tRNA synthetase 1 antibody for brushing cytology of bile duct cancer

BACKGROUND AND AIMS

Identifying malignant biliary strictures using endobiliary brushing cytology specimens is important for treatment decision-making and prognosis prediction. The sensitivity of brushing cytology specimens based on Papanicolaou (Pap) staining is low, which hampers accurate diagnosis of indeterminate strictures. Here, we assessed the diagnostic value of immunohistochemical (IHC) and immunofluorescence (IF) staining for methionyl-tRNA synthetase 1 (MARS1).

METHODS

Endobiliary brushing cytology specimens were obtained during ERCP from 80 patients with an extrahepatic biliary stricture. Pap and MARS1 IF staining were performed on liquid-based cytology slides derived from these specimens. Sections of bile duct adenocarcinoma and normal bile duct tissue were obtained from 45 patients who underwent surgery for malignant biliary stricture, and MARS1 levels were evaluated by IHC staining.

RESULTS

MARS1 IF staining was applied to brushing cytology specimens, and the results showed strong signals in malignant biliary structures but not in the negative for malignancy specimens. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 70.4%, 96.2%, 97.4%, 56.8%, and 78.8%, respectively, for conventional Pap staining and 98.1%, 96.1%, 98.1%, 96.2%, and 97.5%, respectively, for MARS1 IF (P < .0001). When IHC staining was used, MARS1 was detected in 45 bile duct adenocarcinoma sections but not in 15 normal bile duct sections. Moreover, MARS1 mRNA and protein levels were significantly higher in bile duct adenocarcinoma sections according to polymerase chain reaction and Western blot, respectively.

CONCLUSIONS

The high sensitivity and accuracy of MARS1 IF staining enabled detection of malignancy in patients with indeterminate biliary stricture. Further prospective studies are needed to validate our findings. (Clinical trial registration number: KCT 0003285.).

Aminoacyl-tRNA synthetases as therapeutic targets

Aminoacyl-tRNA synthetases (ARSs) are essential enzymes for protein synthesis with evolutionarily conserved enzymatic mechanisms. Despite their similarity across organisms, scientists have been able to generate effective anti-infective agents based on the structural differences in the catalytic clefts of ARSs from pathogens and humans. However, recent genomic, proteomic and functionomic advances have unveiled unexpected disease-associated mutations and altered expression, secretion and interactions in human ARSs, revealing hidden biological functions beyond their catalytic roles in protein synthesis. These studies have also brought to light their potential as a rich and unexplored source for new therapeutic targets and agents through multiple avenues, including direct targeting of the catalytic sites, controlling disease-associated protein-protein interactions and developing novel biologics from the secreted ARS proteins or their parts. This Review addresses the emerging biology and therapeutic applications of human ARSs in diseases including autoimmune and rare diseases, and cancer.

Attenuation of steatohepatitis, fibrosis, and carcinogenesis in mice fed a methionine-choline deficient diet by CCAAT/enhancer-binding protein homologous protein deficiency

BACKGROUND AND AIMS

Hepatic steatosis is a metabolic liver disease with the potential to progress to steatohepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The aim of this study was to investigate the impact of CCAAT/enhancer-binding protein homologous protein (CHOP) deficiency in the development of steatosis-associated progression of HCC.

METHODS

Eight-week-old wild-type (WT) and CHOP knockout (CHOP-/-) mice were fed a normal or methionine-choline-deficient (MCD) diet. Mice were sacrificed after 3 weeks, and steatosis, inflammation, apoptosis, and liver damage were assessed. We also evaluated fibrosis after 8 weeks of nutrition intervention. To explore the role of CHOP in liver carcinogenesis, 25 mg/kg of diethylnitrosamine (DEN) was injected intraperitoneally into 2-week-old mice, which were then fed the aforementioned diets from 8 to 24 weeks of age. CHOP expression in HCC patient livers was also evaluated.

RESULTS

CHOP deficiency did not affect steatosis but significantly reduced apoptotic cells, inflammation scores, and serum liver enzymes. It also significantly suppressed total serum bilirubin levels, fibrotic area size, and messenger RNA expression of profibrotic cytokines. DEN-initiated carcinogenesis was promoted by the MCD diet, while CHOP deficiency significantly attenuated the total number and maximum diameter of tumors and the Ki-67 labeling index. In human livers, CHOP expression was enhanced in parallel with non-alcoholic steatohepatitis-to-HCC progression.

CONCLUSIONS

CHOP deficiency attenuated apoptosis, inflammation, fibrosis, and tumorigenesis under fat-loading conditions, indicating that a therapeutic strategy targeting CHOP might be effective for fat-induced liver injury and protecting against promotion of carcinogenesis in patients with liver steatosis.

Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells

How cells degenerate from oxidative stress in aging-related disease is incompletely understood. This study's intent was to identify key cytoprotective pathways activated by oxidative stress and determine the extent of their protection. Using an unbiased strategy with microarray analysis, we found that retinal pigmented epithelial (RPE) cells treated with cigarette smoke extract (CSE) had overrepresented genes involved in the antioxidant and unfolded protein response (UPR). Differentially expressed antioxidant genes were predominantly located in the cytoplasm, with no induction of genes that neutralize superoxide and H2O2 in the mitochondria, resulting in accumulation of superoxide and decreased ATP production. Simultaneously, CSE induced the UPR sensors IRE1α, p-PERK, and ATP6, including CHOP, which was cytoprotective because CHOP knockdown decreased cell viability. In mice given intravitreal CSE, the RPE had increased IRE1α and decreased ATP and developed epithelial-mesenchymal transition, as suggested by decreased LRAT abundance, altered ZO-1 immunolabeling, and dysmorphic cell shape. Mildly degenerated RPE from early age-related macular degeneration (AMD) samples had prominent IRE1α, but minimal mitochondrial TOM20 immunolabeling. Although oxidative stress is thought to induce an antioxidant response with cooperation between the mitochondria and the ER, herein we show that mitochondria become impaired sufficiently to induce epithelial-mesenchymal transition despite a protective UPR. With similar responses in early AMD samples, these results suggest that mitochondria are vulnerable to oxidative stress despite a protective UPR during the early phases of aging-related disease.

Biomarkers of histone deacetylase inhibitor activity in a phase 1 combined-modality study with radiotherapy

BACKGROUND

Following the demonstration that histone deacetylase inhibitors enhanced experimental radiation-induced clonogenic suppression, the Pelvic Radiation and Vorinostat (PRAVO) phase 1 study, combining fractionated radiotherapy with daily vorinostat for pelvic carcinoma, was designed to evaluate both clinical and novel biomarker endpoints, the latter relating to pharmacodynamic indicators of vorinostat action in clinical radiotherapy.

PATIENTS AND METHODS

Potential biomarkers of vorinostat radiosensitizing action, not simultaneously manifesting molecular perturbations elicited by the radiation itself, were explored by gene expression array analysis of study patients' peripheral blood mononuclear cells (PBMC), sampled at baseline (T0) and on-treatment two and 24 hours (T2 and T24) after the patients had received vorinostat.

RESULTS

This strategy revealed 1,600 array probes that were common for the comparisons T2 versus T0 and T24 versus T2 across all of the patients, and furthermore, that no significantly differential expression was observed between the T0 and T24 groups. Functional annotation analysis of the array data showed that a significant number of identified genes were implicated in gene regulation, the cell cycle, and chromatin biology. Gene expression was validated both in patients' PBMC and in vorinostat-treated human carcinoma xenograft models, and transient repression of MYC was consistently observed.

CONCLUSION

Within the design of the PRAVO study, all of the identified genes showed rapid and transient induction or repression and therefore, in principle, fulfilled the requirement of being pharmacodynamic biomarkers of vorinostat action in fractionated radiotherapy, possibly underscoring the role of MYC in this therapeutic setting.

CHOP regulates the p53-MDM2 axis and is required for neuronal survival after seizures

Hippocampal sclerosis is a frequent pathological finding in patients with temporal lobe epilepsy and can be caused by prolonged single or repeated brief seizures. Both DNA damage and endoplasmic reticulum stress have been implicated as underlying molecular mechanisms in seizure-induced brain injury. The CCAAT/enhancer-binding protein homologous protein (CHOP) is a transcriptional regulator induced downstream of DNA damage and endoplasmic reticulum stress, which can promote or inhibit apoptosis according to context. Recent work has proposed inhibition of CHOP as a suitable neuroprotective strategy. Here, we show that transcript and protein levels of CHOP increase in surviving subfields of the hippocampus after prolonged seizures (status epilepticus) in mouse models. CHOP was also elevated in the hippocampus from epileptic mice and patients with pharmacoresistant epilepsy. The hippocampus of CHOP-deficient mice was much more vulnerable to damage in mouse models of status epilepticus. Moreover, compared with wild-type animals, CHOP-deficient mice subject to status epilepticus developed more spontaneous seizures, displayed protracted hippocampal neurodegeneration and a deficit in a hippocampus-dependent object-place recognition task. The absence of CHOP was associated with a supra-maximal induction of p53 after status epilepticus, and inhibition of p53 abolished the cell death-promoting consequences of CHOP deficiency. The protective effect of CHOP could be partly explained by activating transcription of murine double minute 2 that targets p53 for degradation. These data demonstrate that CHOP is required for neuronal survival after seizures and caution against inhibition of CHOP as a neuroprotective strategy where excitotoxicity is an underlying pathomechanism.

Association of aminoacyl-tRNA synthetases with cancer

Although aminoacyl-tRNA synthetases (ARSs) and ARS-interacting multi-functional proteins (AIMPs) have long been recognized as housekeeping proteins, evidence indicating that they play a key role in regulating cancer is now accumulating. In this chapter we will review the conventional and non-conventional functions of ARSs and AIMPs with respect to carcinogenesis. First, we will address how ARSs and AIMPs are altered in terms of expression, mutation, splicing, and post-translational modifications. Second, the molecular mechanisms for ARSs' and AIMPs' involvement in the initiation, maintenance, and progress of carcinogenesis will be covered. Finally, we will introduce the development of therapeutic approaches that target ARSs and AIMPs with the goal of treating cancer.

Expression of CHOP in squamous tumor of the uterine cervix

Background

High-risk human papillomavirus (HR-HPV) infection and abnormal p53 expression are closely involved in carcinogenesis of squamous cell carcinoma (SqCC) of uterine cervix. Recent studies have suggested that virus-induced endoplasmic reticulum (ER) stress modulates various cell survival and cell death signaling pathways. The C/EBP homologous protein (CHOP) is associated with ER stress-mediated apoptosis and is also involved in carcinogenesis of several human cancers. We hypothesized that CHOP is involved in the carcinogenesis of uterine cervical cancer in association with HR-HPV and/or p53.

Methods

Immunohistochemistry was used to analyze CHOP and p53 protein expression of tissue sections from 191 patients with invasive cancer or preinvasive lesions of the uterine cervix (61 cases of SqCC, 66 cases of cervical intraepithelial neoplasia [CIN] III, and 64 cases of CIN I).

Results

CHOP was expressed in 59.4% of CIN I, 48.5% of CIN III, and 70.5% of SqCC cases. It was also significantly more frequent in invasive SqCC than in preinvasive lesions (p=0.042). Moreover, CHOP expression significantly correlated with HR-HPV infection and p53 expression (p=0.009 and p=0.038, respectively).

Conclusions

Our results suggest that CHOP is involved in the carcinogenesis of the uterine cervix SqCC via association with HR-HPV and p53.

Aminoacyl-tRNA synthetases and tumorigenesis: more than housekeeping

Over the past decade, the identification of cancer-associated factors has been a subject of primary interest not only for understanding the basic mechanisms of tumorigenesis but also for discovering the associated therapeutic targets. However, aminoacyl-tRNA synthetases (ARSs) have been overlooked, mostly because many assumed that they were simply 'housekeepers' that were involved in protein synthesis. Mammalian ARSs have evolved many additional domains that are not necessarily linked to their catalytic activities. With these domains, they interact with diverse regulatory factors. In addition, the expression of some ARSs is dynamically changed depending on various cellular types and stresses. This Analysis article addresses the potential pathophysiological implications of ARSs in tumorigenesis.

Molecular approaches to sarcoma therapy

Soft tissue sarcomas comprise a heterogeneous group of aggressive tumors that have a relatively poor prognosis. Although conventional therapeutic regimens can effectively cytoreduce the overall tumor mass, they fail to consistently achieve a curative outcome. Alternative gene-based approaches that counteract the underlying neoplastic process by eliminating the clonal aberrations that potentiate malignant behavior have been proposed. As compared to the accumulation of gene alterations associated with epithelial carcinomas, sarcomas are frequently characterized by the unique presence of a single chromosomal translocation in each histological subtype. Similar to the Philadelphia chromosome associated with CML, these clonal abnormalities result in the fusion of two independent unrelated genes to generate a unique chimeric protein that displays aberrant activity believed to initiate cellular transformation. Secondary gene mutations may provide an additional growth advantage that further contributes to malignant progression. The recent clinical success of the tyrosine kinase inhibitor, STI571, suggests that therapeutic approaches specifically directed against essential survival factors in sarcoma cells may be effective. This review summarizes published approaches targeting a specific molecular mechanism associated with sarcomagenesis. The strategy and significance of published translational studies in six distinct areas are presented. These include: (1) the disruption of chimeric transcription factor activity; (2) inhibition of growth stimulatory post-translational modifications; (3) restoration of tumor suppressor function; (4) interference with angiogenesis; (5) induction of apoptotic pathways; and (6) introduction of toxic gene products. The potential for improving outcomes in sarcoma patients and the conceptual obstacles to be overcome are discussed.

Aminoacyl tRNA synthetases and their connections to disease

Aminoacylation of transfer RNAs establishes the rules of the genetic code. The reactions are catalyzed by an ancient group of 20 enzymes (one for each amino acid) known as aminoacyl tRNA synthetases (AARSs). Surprisingly, the etiology of specific diseases-including cancer, neuronal pathologies, autoimmune disorders, and disrupted metabolic conditions-is connected to specific aminoacyl tRNA synthetases. These connections include heritable mutations in the genes for tRNA synthetases that are causally linked to disease, with both dominant and recessive disease-causing mutations being annotated. Because some disease-causing mutations do not affect aminoacylation activity or apparent enzyme stability, the mutations are believed to affect functions that are distinct from aminoacylation. Examples include enzymes that are secreted as procytokines that, after activation, operate in pathways connected to the immune system or angiogenesis. In addition, within cells, synthetases form multiprotein complexes with each other or with other regulatory factors and in that way control diverse signaling pathways. Although much has been uncovered in recent years, many novel functions, disease connections, and interpathway connections of tRNA synthetases have yet to be worked out.

Endoplasmic reticulum stress in disease pathogenesis

The endoplasmic reticulum (ER) is the site of synthesis and folding of membrane and secretory proteins, which, collectively, represent a large fraction of the total protein output of a mammalian cell. Therefore, the protein flux through the ER must be carefully monitored for abnormalities, including the buildup of misfolded proteins. Mammalian cells have evolved an intricate set of signaling pathways from the ER to the cytosol and nucleus, to allow the cell to respond to the presence of misfolded proteins within the ER. These pathways, known collectively as the unfolded protein response, are important for normal cellular homeostasis and organismal development and may also play key roles in the pathogenesis of many diseases. This review provides background information on the unfolded protein response and discusses a selection of diseases whose pathogenesis involves ER stress.

Mapping and characterization of the amplicon near APOA2 in 1q23 in human sarcomas by FISH and array CGH

BACKGROUND

Amplification of the q21-q23 region on chromosome 1 is frequently found in sarcomas and a variety of other solid tumours. Previous analyses of sarcomas have indicated the presence of at least two separate amplicons within this region, one located in 1q21 and one located near the apolipoprotein A-II (APOA2) gene in 1q23. In this study we have mapped and characterized the amplicon in 1q23 in more detail.

RESULTS

We have used fluorescence in situ hybridisation (FISH) and microarray-based comparative genomic hybridisation (array CGH) to map and define the borders of the amplicon in 10 sarcomas. A subregion of approximately 800 kb was identified as the core of the amplicon. The amplification patterns of nine possible candidate target genes located to this subregion were determined by Southern blot analysis. The genes activating transcription factor 6 (ATF6) and dual specificity phosphatase 12 (DUSP12) showed the highest level of amplification, and they were also shown to be over-expressed by quantitative real-time reverse transcription PCR (RT-PCR). In general, the level of expression reflected the level of amplification in the different tumours. DUSP12 was expressed significantly higher than ATF6 in a subset of the tumours. In addition, two genes known to be transcriptionally activated by ATF6, glucose-regulated protein 78 kDa and -94 kDa (GRP78 and GRP94), were shown to be over-expressed in the tumours that showed over-expression of ATF6.

CONCLUSION

ATF6 and DUSP12 seem to be the most likely candidate target genes for the 1q23 amplification in sarcomas. Both genes have possible roles in promoting cell growth, which makes them interesting candidate targets.

Amplification of chromosome 1 sequences in lipomatous tumors and other sarcomas

Amplifications and gains involving 1q are common abnormalities in solid tumors. Recently, an amplicon originating from 1q21-23, containing the candidate oncogenes COAS1, COAS2 and COAS3 (Chromosome One Amplified Sequence) was identified. The presence, distribution and copy number level of extra COAS sequences were investigated in 48 bone and soft tissue tumor (BSTT) samples using metaphase FISH analysis. Amplification was seen in 27/48 (56%) samples. With few exceptions, all 3 genes were involved, but on average COAS2 exhibited higher copy numbers. The presence of extra COAS signals, irrespective of copy numbers, was found at similar frequencies in different histologic tumor subtypes. However, medium or high level amplification was common in lipomatous tumors but rare in other, nonlipomatous tumors (9/21 vs. 2/27 samples). The most common localization of extra COAS signals in lipomatous tumors was in supernumerary ring and giant marker chromosomes. Among nonlipomatous tumors, the distribution of extra COAS genes was more disperse, being located in various unidentified chromosomal structures, including double minutes, and only rarely in ring chromosomes. Because MDM2 is known to be amplified frequently in BSTTs, and in particular in atypical lipomatous tumors, cases with extra copies of COAS were studied also with an MDM2 probe. Twelve out of 18 lipomatous tumors had extra copies of both COAS and MDM2, and the 2 genes were found to be coamplified and interspersed exclusively in ring and giant marker chromosomes. Also 12 out of 18 nonlipomatous tumors exhibited simultaneous gain of COAS and MDM2, but colocalization in the same chromosome was less frequent. The role of the frequent coamplification of COAS, or some other yet unknown gene in the 1q21-23 region, and MDM2 remains to be elucidated.

Genetic imbalances revealed by comparative genomic hybridization in osteosarcomas

Osteosarcomas are the most frequent bone sarcomas. The molecular chromosomal aberrations in osteosarcomas were analyzed by comparative genomic hybridization (CGH). We studied 47 frozen tumors (41 primary samples, 6 relapses) in osteosarcoma patients registered in the Cooperative Osteosarcoma Study (COSS) protocol. Genomic imbalances were detected in 40 of 41 primary tumors and 6 of 6 relapsed tumors. Gains were more frequent than losses (ratio of 1.3:1). The median number of changes was 16 and 12 in primary and relapsed osteosarcomas, respectively. The median number of aberrations in primary high-grade osteosarcomas (17.0) was significantly higher than in low- or intermediate-grade osteosarcoma subtypes (3.0) (p = 0.038). The most frequent gains included 8q, 1p21-p31 and 1q21-q24, and the most frequent losses were 10q, 5q and 13q. High-level gains were observed on 8q23-q24, 17p13 and 1q21-q24. A gain of 19p (p < 0.001) or loss of 9p (p = 0.027) was more frequent in poor responders than in good responders. Univariate analysis revealed that patients with primary metastases (p = 0.002), poor histologic responses (p = 0.005), high-level gains of 19p (p = 0.012) or losses of 13q14 (p = 0.042) had significantly lower event-free survival (EFS), whereas patients with a loss of 5q (p = 0.007) or a loss of 10q21-22 (p = 0.017) had significantly higher EFS than patients without these aberrations. Multivariate analysis demonstrated that primary metastasis, loss of 13q14 and loss of 5q were independent prognostic factors. The findings of our study seem to be useful for evaluating the prognosis of patients and may finally lead to treatment strategies based on genetic background of osteosarcoma.

Increased expression of the transcription factors CCAAT-enhancer binding protein-beta (C/EBBeta) and C/EBzeta (CHOP) correlate with invasiveness of human colorectal cancer

Regulation of cell differentiation is most often impaired in malignant tumors and may represent a key mechanism for the progression of the disease. CCAAT-enhancer binding protein (C/EBP) is a family of transcription factors involved in the regulation of embryonic gut development in rodents, which has also been detected in various malignancies, e.g., liposarcomas and breast and ovarian epithelial tumors. We studied the relationship between C/EBP and tumor histology (Duke's invasive stage and pathological grade) in colorectal cancer. Immunoblotting techniques were used on microdissected fresh frozen tumor specimens, and expression of C/EBPalpha, C/EBPbeta and C/EBPzeta (CHOP) was analyzed in addition to that of the cell-cycle regulator p53 and the proliferation marker PCNA. Expression of C/EBPbeta (LAP isoforms) was markedly increased in all tumors compared with normal colon mucosa. Although the inter-patient variability was large, we found that LIP, the isoform of C/EBPbeta known to inhibit transcription, was expressed at higher levels in Duke's stage B tumors compared with Duke's stage A, whereas Duke's C tumors had the lowest LIP expression. A similar relationship was seen for CHOP. The cell-cycle regulator gene p53 was the only factor that clearly correlated with pathological grade: a decrease in p53 expression was demonstrated. Our data suggest that genetic and cellular events involving C/EBPbeta and CHOP are important for tumor invasion and that these events do not appear to be related to the pathological grade of the tumor.

Supernumerary ring chromosomes derived from the long arm of chromosome 12 as the primary cytogenetic anomaly in a rare soft tissue chondroma

Supernumerary ring chromosomes varying with respect to both size and number were found as the primary cytogenetic anomaly in a rare benign soft tissue chondroma resected from the floor of the mouth of a 3-year-old girl. Reverse fluorescence in situ hybridization paint probes prepared by polymerase chain reaction from microdissected rings produced fluorescent signal over two large but discontinuous parts of the chromosome 12 long arm, subdivided into four regions. This case expands the spectrum of mesenchymal neoplasms in which ring chromosomes have been described as the primary genetic anomaly. A review of the literature reporting similar findings in other soft tissue tumors further supports the possibility that low-level amplification of chromosome 12 long-arm regions may contribute to abnormal cellular proliferation in a variety of mesenchymal tumors. Genes implicated in the control of the cell cycle such as sarcoma amplified sequence (SAS), the human homolog of the murine double-minute type 2 gene (MDM-2), proto-oncogenes CHOP/GADD153, GLI, A2MR, cyclin-dependent kinase (CDK4), and the high mobility group (HMGIC) gene implicated in mesenchymal tumorigenesis are all located on the long arm of chromosome 12. Chromosomal abnormalities involving the 12q13-q15 region are associated with a wide range of benign soft tissue tumors and sarcomas.

Comparative genomic hybridization reveals novel chromosome deletions in 90 primary soft tissue tumors

Comparative genomic hybridization (CGH) was used to detect chromosomal gains and losses in a series of 90 frozen soft tissue primary tumors (STTs), all untreated. The material consisted of 69 malignant sarcomas, including 20 malignant fibrous histiocytomas (MFH), 23 liposarcomas (LPS), 6 leiomyosarcomas (LMS), 4 synovial sarcomas, 4 primitive neuroectodermal tumors (PNETs), and various others subtypes, in addition to 21 benign tumors. Within the benign tumors, only 2 of the 3 schwannomas showed genetic changes. In malignant sarcomas, genetic changes were detected in 64 of the 69 samples analyzed (92%), with a mean of 4.5 per sample (range 0-10). Gains and losses on chromosome 13 were observed in 32% of the sarcomas with genomic imbalance. Recurring low-level copy number increases were found at new sites on chromosomes 7 (6 MFH samples, 30%) and 8 (10 LPS samples, 43%), the minimal common regions being 7p15-pter and 8q24. No new recurring high-level amplifications were found. Surprisingly, losses of DNA sequences were more frequent than gains; particularly, losses were the main feature in LMS, with highly recurrent common minimal losses at 11q14-qter and 13q21-q22 (4 samples, 66%, and 5 samples, 83%, respectively). Losses of chromosome 2 sequences (minimal common regions at 2p24-pter and 2q32-qter) were observed in 50% of the MFH analyzed. New recurrent losses of whole or part of chromosome 14 were found in 57% of the pleomorphic LPS (PLPS) analyzed. This study uncovers new clues for the diagnosis of malignant STTs and shows the importance of deletions as events in the early steps involved in the tumorigenesis of STTs.

Amplifications of DNA primase 1 (PRIM1) in human osteosarcoma

We studied the involvement of PRIM1 in osteosarcoma by differential display, Northern and Southern hybridization, as well as fluorescence in situ hybridization (FISH) on interphase nuclei. In total, 22 pediatric oncology specimens were tested. PRIM1 was found to be amplified in 41% of the samples. PRIM1 is coamplified with the core 12q13 amplicon genes CDK4, SAS, and OS9, and was physically mapped very close to them. PRIM1 is therefore a new candidate for the role of a major target gene of 12q13 amplifications in human cancers. Genes Chromosomes Cancer 26:62-69, 1999.

CHOP/GADD153 and methionyl-tRNA synthetase (MetRS) genes overlap in a conserved region that controls mRNA stability

The transcription factor CHOP is involved in the regulation of the cell division cycle and the control of programmed cell death in response to cellular stress. CHOP expression has been linked with several forms of cancer. A reciprocal translocation between the CHOP and TLS RNA-binding protein gene results in myxoid liposarcoma and amplifications of the CHOP gene are associated with solid tumors including several types of sarcomas. Here we report the mapping of the methionyl tRNA synthetase (MetRS) gene to the identical 12q13 locus where the CHOP gene had previously been mapped. PCR analysis demonstrates a tail-to-tail overlap of both genes over a 55-bp region. As a result the two mRNAs share a 3' UTR complementary sequence allowing an in vivo interaction between the two mRNAs. An AU-rich regulatory element (ARE) known to control mRNA stability resides in the overlapping sequence. To test for functional significance of the ARE a luciferase reporter plasmid containing the 3'UTR of CHOP was constructed. Transfection experiments in NIH-3T3 cells show that CHOP 3'UTR confers a significantly lower activity than a control reporter or a reporter in which the region overlapping the MetRS mRNA is deleted. The conservation of this overlapping of the CHOP and MetRS genes and the role of their complementary sequence in the control of mRNA stability suggest the existence of a functional link between the expression of these two genes.

DNA sequence copy number increase at 8q: a potential new prognostic marker in high-grade osteosarcoma

Histologic response to chemotherapy is currently the best prognostic parameter in high-grade osteosarcoma but it can be evaluated only after several weeks of chemotherapy. Thus a prognostic parameter known at the time of diagnosis would be of great clinical benefit. In the present study, we present the results of 31 primary high-grade osteosarcomas analyzed by comparative genomic hybridization (CGH). CGH allows for genome-wide screening of a tumor by detecting alterations in DNA sequence copy number. The most frequent aberrations were copy number increases at 1q21 in 58% of the tumors and at 8q (8q21.3-q22 in 52% and 8cen-q13 in 45%), followed by copy number increases at 14q24-qter (35%) and Xp11.2-p21 (35%). The most common losses were detected at 6q16 (32%) and 6q21-q22 (32%). Patients with a copy number increase at 8q21.3-q22 and/or at 8cen-q13 had a statistically significant poor distant disease-free survival (p = 0.003) and showed a trend toward short overall survival (p = 0.04). Patients with a copy number increase at 1q21 showed a trend toward short overall survival (p = 0.04). Thus, specific genetic aberrations detected at the time of the diagnosis could be used in prognostic evaluation of high-grade osteosarcoma.

[Unusual course of hemangiopericytoma]

BACKGROUND

Hemangiopericytomas, rare perivascular tumors, normally tend to be well circumscribed, however, since some have a malignant behavior they are recognized to be potentially malignant.

CASE REPORT

In the case presented here, we report the medical history of a 46-year-old man with a hemangiopericytoma of the nose. In 1983, the tumor was surgically removed, and histological examination revealed no signs of malignancy. In 1987, a local recurrence was removed followed by X-irradiation. In March 1995, the patient presented with multiple hepatic and bone metastases. Chemotherapy with ifosfamide (5 g/m2, day 1) and epirubicin (50 mg/m2, day 1) was performed. After three courses of chemotherapy a tumor stabilization was achieved. In November 1995, however, a massive progression of the hepatic lesions was found. Therefore, six courses of a second-line chemotherapy with dacarbazine (200 mg/m2, day 1 to 5) and adriamycin (60 mg/m2, day 1) were applied. A partial remission was achieved lasting until November 1996. A couple of weeks later the patient died due to hepatic failure.

CONCLUSION

Despite of unacceptably low survival rates in patients with advanced soft tissue sarcomas (especially after pretreatment with ionizing radiation) our report demonstrates that it is also possible to induce long lasting remissions without altered quality of life.

Chromosomal organization of amplified chromosome 12 sequences in mesenchymal tumors detected by fluorescence in situ hybridization

The chromosomal organization of amplified chromosome 12 sequences was studied with fluorescence in situ hybridization in six mesenchymal tumors: two osteosarcomas, one lipoma, two liposarcomas, and one fibrosarcoma. All except the fibrosarcoma contained ring and/or giant marker chromosomes. Amplification of chromosome 12 sequences, demonstrated with whole-chromosome paint in all cases, was confined to ring and giant marker chromosomes in four tumors. In one of the osteosarcomas and in the fibrosarcoma, amplified sequences were added to chromosome 12 and to chromosomes 10, 12, 18, and the Y chromosome, respectively. Hybridizations with single-copy probes demonstrated considerable inter- and intracellular variation in the arrangement of chromosome 12 sequences in ring and marker chromosomes. Amplification of 12q13-15 sequences, predominantly from the HMGIC-MDM2 region, was detected in all cases, but the two osteosarcomas also contained amplification of 12p material. This finding, combined with results from previous studies, indicates that 12p amplification is a feature distinguishing osteosarcomas from adipose tissue tumors. A novel finding was the presence of positive signals for chromosome 12 alpha-satellite sequences in ring and marker chromosomes in four cases. Rod chromosomes carrying amplified material, in particular those that were relatively stable, frequently exhibited chromosome 12 negative terminal segments; two of these, present in two separate cases, were shown by C-banding to contain constitutive heterochromatin. The significant intercellular heterogeneity in the number and structure of rings and giant markers in a subset of mesenchymal tumors could be explained by continuous recombination through breakage-fusion-bridge cycles. If so, this process will continue until broken ends become stabilized, for example by acquisition of telomeric segments from other chromosomes.

Overrepresentation of 1q21-23 and 12q13-21 in lipoma-like liposarcomas but not in benign lipomas: a comparative genomic hybridization study

Twenty lipomatous tumors, including eight lipoma-like liposarcomas and 12 benign lipomas, were analyzed using comparative genomic hybridization (CGH). DNA sequence copy number changes detected in five lipoma-like liposarcomas (mean, 1.1 aberrations/tumor; range, 0-2) consisted of gains of 12q13-21 (five tumors) and 1q21-23 (four tumors). Two of the tumors showed high-level amplification at 12q14-21 and one tumor at 1q21-22. No copy number changes were found in lipomas. Overrepresentation of 1q and 12q sequences was a recurrent finding in lipoma-like liposarcomas but not in lipomas. Thus, CGH may help in the differential diagnosis of low-grade or borderline adipose neoplasms.

Microsatellite markers as tools for characterization of DNA amplifications evaluated by comparative genomic hybridization

To test the applicability of microsatellite markers in the study of DNA amplifications evaluated by comparative genomic hybridization, we analyzed 55 highly polymorphic microsatellite marker loci from six liposarcoma tumors (seven specimens) and from one atypical lipoma with a gain or high-level amplification at 12q13-22. Twelve-trisomic neoplastic cells from a patient with B-cell chronic lymphocytic leukemia were used as a positive control, in which 74% of informative loci showed allelic imbalance. In every tumor specimen microsatellite marker loci analysis showed allelic imbalance. The amplicons were discontinuous, indicating the presence of separate amplicons in the 12q13-22 region. Not only gains but also losses as well as concomitant gains and losses of alleles were observed. The use of microsatellite markers has several advantages: gene loci as well as flanking DNA loci can be analyzed, it is fast and lends itself to automation, and allows a large number of marker loci to be analyzed simultaneously.

Complexity of 12q13-22 amplicon in liposarcoma: microsatellite repeat analysis

The 12q13-22 amplicon from four liposacroma specimens evaluated by comparative genomic hybridization was studied analyzing 55 microsatellite markers by PCR. All four specimens were informative in at least 34 loci; an amplification or allelic imbalance was identified with four to 17 markers. The amplicons were discontinuous; there were non-amplified marker loci between the amplified marker loci. These findings indicate the presence of separate amplicons in the 12q13-22 region. Evidence of the concomitant gain of one allele and loss of the other allele was found with several markers in one tumor and with one marker in two tumor specimens. Southern blotting showed amplification of CDK4 and MDM2 in all four specimens.

Separate amplified regions encompassing CDK4 and MDM2 in human sarcomas

Amplification of MDM2 and CDK4 is observed frequently in human sarcomas. Although overexpression of these protooncogenes might inhibit growth regulation through the TP53- and retinoblastoma tumor suppressor protein (RB)-mediated pathways, neither gene was included consistently in all of the amplicons observed in our sarcoma panel. It was unclear whether both of these genes were selected for during amplification. Furthermore, in some samples without amplification of MDM2 or CDK4, comparative genomic hybridization showed amplification in the 12q13-15 region, suggesting that another selection mechanism might also be involved. To investigate the possibility that another target gene, which may be located between CDK4 and MDM2, could be the driving force, we characterized the involvement of 17 loci from this region in 12q13-15 amplicons that were detected previously in 21 sarcoma samples. The results showed discrete amplicons around MDM2 and CDK4 with reduced amplification of the intervening sequences. This suggests that there is separate selection for amplification of the two genes, and it makes the possibility of a common selective gene unlikely. Furthermore, D12S8, localized distal to MDM2, was amplified almost as frequently as MDM2 and was also amplified in one of the samples without MDM2 or CDK4 amplification. The data suggest that amplification of at least three different regions within the 12q13-15 segment may be selected for in tumor cells involving MDM2, CDK4, or a more distally located gene, possibly near D12S8.

Gains and losses of DNA sequences in liposarcomas evaluated by comparative genomic hybridization

Comparative genomic hybridization (CGH) was used to detect and map the regions of gain, high-level amplification, and loss of DNA sequences in 14 liposarcomas. Thirteen tumors showed DNA sequence copy number changes of one or more genomic regions (mean, six aberrations/tumor; range, 0-17). These aberrations were observed in almost every chromosome but some chromosomal regions were affected more often than others. DNA sequence gains were more frequent than losses. The most common gain was seen at 12q14-21 (50% of tumors). Other frequent gains (29%) were of 1q21-24, 8cen-q21.2, 19q, and 20q. High-level amplification was observed in six (43%) tumors and included as minimal common segments bands 12q15, 1q22, and 1q24. In five (36%) tumors, sequences at 1q21-24 and 1q32 were found to be gained simultaneously with 12q14-21, which means that in 71% of the tumors with gain at 12q, an increase of DNA sequence copy number at 1q was also observed. The most common losses of DNA sequences (21%) occurred from regions 9p21-pter and 13q21-qter. Most of the aforementioned regions have not previously been reported to be altered in liposarcomas. The detection of a novel recurring amplicon at 1q21-24 with high-level amplification at 1q22 and frequent simultaneous DNA sequence gain at 12q14-21 (high-level amplification at 12q15) suggests that genes linked to both these regions may play a significant role in the development and progression of liposarcomas.

Identification of two distinct chromosome 12-derived amplification units in neuroblastoma cell line NGP

The neuroblastoma cell line NGP contains two homogeneously staining regions (hsr). One of these hsrs contains MYCN sequences. Reverse painting experiments demonstrated that the second HSR consisted of two chromosome 12-derived amplification units, located at 12q14-15 and 12q24. Southern blot and fluorescence in situ hybridization (FISH) analysis showed amplification of genes located at 12q14-15: SAS, MDM2, and CDK4, GLI, CHOP, CDK2, and A2MR were found not to be amplified. FISH further demonstrated amplification of RSN, a gene located at 12q24. The finding of two distinct chromosome 12 amplification units in a neuroblastoma cell line NGP is reminiscent of recent findings in well-differentiated liposarcoma (WDLPS) and other sarcomas. The second amplification unit on chromosome 12 in NGP is located more distal (12q24) than the one observed in WDLPS (12q21). The mechanism and biologic significance of this amplification process in neuroblastoma and WDLPS remain to be elucidated.