Yukichi Tanaka

Germline mutations in HRAS proto-oncogene cause Costello syndrome

Costello syndrome is a multiple congenital anomaly and mental retardation syndrome characterized by coarse face, loose skin, cardiomyopathy and predisposition to tumors. We identified four heterozygous de novo mutations of HRAS in 12 of 13 affected individuals, all of which were previously reported as somatic and oncogenic mutations in various tumors. Our observations suggest that germline mutations in HRAS perturb human development and increase susceptibility to tumors.

Deletions and epimutations affecting the human 14q32.2 imprinted region in individuals with paternal and maternal upd(14)-like phenotypes.

Human chromosome 14q32.2 carries a cluster of imprinted genes including paternally expressed genes (PEGs) such as DLK1 and RTL1 and maternally expressed genes (MEGs) such as MEG3 (also known as GTL2), RTL1as (RTL1 antisense) and MEG8 (refs. 1,2), together with the intergenic differentially methylated region (IG-DMR) and the MEG3-DMR. Consistent with this, paternal and maternal uniparental disomy for chromosome 14 (upd(14)pat and upd(14)mat) cause distinct phenotypes. We studied eight individuals (cases 1–8) with a upd(14)pat-like phenotype and three individuals (cases 9–11) with a upd(14)mat-like phenotype in the absence of upd(14) and identified various deletions and epimutations affecting the imprinted region. The results, together with recent mouse data, imply that the IG-DMR has an important cis-acting regulatory function on the maternally inherited chromosome and that excessive RTL1 expression and decreased DLK1 and RTL1 expression are relevant to upd(14)pat-like and upd(14)mat-like phenotypes, respectively.

Fusion of an ETS-family gene, EIAF, to EWS by t(17;22)(q12;q12) chromosome translocation in an undifferentiated sarcoma of infancy

EIAF is a newly isolated ETS‐family gene that is located on 17q21 and codes for the adenovirus EIA enhancer‐binding protein. In our chromosome analysis of 18 of the Ewing family of tumors and undifferentiated sarcomas, we found t(17;22)(q12;q12) in an MIC2 antigen‐positive undifferentiated sarcoma of infancy. On Southern blot analysis, EWS and EIAF cDNA probes hybridized to the same rearranged band, indicating that an EWS‐EIAF fusion gene was formed in the tumor. Further Southern blot analysis using four EIAF cDNA probes of different sizes showed that the breakpoint lies in the region upstream to the ETS domain of the EIAF gene. EIAF may be the fourth ETS‐family gene to be identified forming a fusion gene with EWS. We assume that the RNA binding domain of EWS may have been replaced by the DNA binding domain of EIAF in the EWS‐EIAF fusion protein as in other fusion proteins previously characterized in Ewing sarcoma and other types of sarcomas. Genes Chromosom Cancer 15:115–121 (1996).

Possible linkage between specific histological structures and aberrant reactivation of the Wnt pathway in adamantinomatous craniopharyngioma

This study concerns the significance of nuclear/cytoplasmic expression of beta‐catenin and mutation of the beta‐catenin gene in craniopharyngiomas. Fourteen adamantinomatous type and one squamous papillary type craniopharyngiomas were studied. Histologically, 13 of 14 adamantinomatous type craniopharyngiomas showed typical features, ie mixtures of ‘palisading cells’, ‘stellate cells’, and ‘ghost cells’. In addition, ‘whorl‐like arrays’ of epithelial cells were frequently observed in the areas of stellate cells. On immunohistochemistry, all typical adamantinomatous type craniopharyngiomas showed nuclear/cytoplasmic expression of beta‐catenin predominantly in cohesive cells within the whorl‐like arrays and in cells transitional towards ghost cells, where immunoreactivity for Ki‐67 was almost absent. The cohesive cells in the whorl‐like arrays also demonstrated loss of cytokeratin isoform expression. Using direct sequencing of amplified nucleic acids, nine of the 13 typical adamantinomatous type craniopharyngiomas with nuclear beta‐catenin accumulation showed heterozygous one‐base substitution mutation of the beta‐catenin gene. The other unusual adamantinomatous type and squamous papillary type craniopharyngiomas showed no obvious nuclear/cytoplasmic beta‐catenin immunoreactivity and no mutation of the beta‐catenin gene, suggesting molecular heterogeneity. These findings suggest that the pathogenesis of typical adamantinomatous type craniopharyngioma is associated with abnormalities of Wnt signalling that act as a morphogenetic signal towards whorl‐like arrays and ghost cells rather than as simple proliferation stimuli. Copyright

Natural Course of Neuroblastoma Detected by Mass Screening: A 5-Year Prospective Study at a Single Institution

PURPOSE To describe various favorable courses of neuroblastoma (NBL) detected by mass screening and to present our observation program as a temporary treatment option, to be used until a final decision is made regarding the mass screening program for 6-month-old infants. PATIENTS AND METHODS Between October 1993 and November 1999, 26 of 51 patients with NBL detected by mass screening were enrolled in our observation program. The criteria for observation included urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) levels less than 50 microg/mg creatinine, smaller tumor size (< 5.0 cm), preoperative status, and granted informed consent. Patients were divided into four groups according to changes in urinary VMA and HVA values and tumor size. Patients who no longer fulfilled criteria underwent surgery. RESULTS The observation period ranged from 4 to 73 months. Urinary VMA and HVA levels decreased in 19 of 26 patients, often by age 16 months. Eighteen patients had regressing tumors, and in 10 of these cases, the tumor was undetectable or barely detectable by imaging techniques. Four patients younger than 12 months had increased tumor marker levels and tumor volume, histologically reflecting neuroblastic proliferation. The remaining three patients, all older than 18 months, had varied tumor marker levels but increased tumor volume, histologically reflecting an increase in Schwann cells. No upgrading of tumor stage or unfavorable biologic factor was noted in any patient. CONCLUSION None of our patients showed evidence of transition from favorable to unfavorable prognosis, a finding that points to a reduction in the significance of screening as a public health measure. Until results of ongoing screening trials involving older patients have been evaluated, the observation program can be used as a temporary measure to avoid, with little risk, unnecessary surgical intervention.

Aberrant Nuclear Localization and Gene Mutation of β-catenin in Low-Grade Adenocarcinoma of Fetal Lung Type: Up-Regulation of the Wnt Signaling Pathway May Be a Common Denominator for the Development of Tumors that Form Morules

The salient histopathologic features of low-grade adenocarcinoma of the fetal lung type (L-FLAC)/well-differentiated fetal adenocarcinoma (WDFA) include complex glandular structures and morules with biotin-rich optically clear nuclei. Interestingly, these characteristic features are shared by the cribriform-morular variant of papillary thyroid carcinoma, whose morphology is identical to that of familial adenomatous polyposis (FAP)-associated thyroid carcinoma. Furthermore, the single reported case of lung cancer associated with FAP was L-FLAC/WDFA. These observations lead us to hypothesize that up-regulation of the Wnt signaling pathway underlies the development of L-FLAC/WDFA. To verify this hypothesis, 11 cases of L-FLAC/WDFA, including the one FAP-associated case, eight cases of high-grade adenocarcinoma of the fetal lung type (H-FLAC), 24 cases of conventional pulmonary adenocarcinoma (CAC), and 13 fetal lungs were immunostained for β-catenin. All cases of L-FLAC/WDFA showed predominantly aberrant nuclear/cytoplasmic expression, especially in budding glands and morules, whereas six of eight cases (75%) of H-FLAC and all but one case (96%) of CAC showed predominantly membranous expression. Fetal lungs showed nuclear/cytoplasmic expression restricted to the distal branching airway epithelium. Mutational analysis of exon 3 of the β-catenin gene in five sporadic cases of L-FLAC/WDFA showed a point mutation at codon 34 and codon 37 in two cases, respectively. The present study indicates that up-regulating disturbances in the Wnt signaling pathway, including mutation of the β-catenin gene, underlie tumorigenesis of L-FLAC/WDFA. The expression pattern of β-catenin in L-FLAC/WDFA resembles that of the developing fetal lung airway. With the expression pattern of β-catenin as a marker, most cases of H-FLAC as well as CAC appear to have different oncogenic pathways from cases of L-FLAC/WDFA. The present study together with other available data also suggests that abnormal up-regulation of the Wnt signaling pathway may be a common denominator for the development of tumors with morular formation from a variety of anatomic sites.

Towards an international pediatric liver tumor consensus classification: proceedings of the Los Angeles COG liver tumors symposium

Liver tumors are rare in children, and their diagnoses may be challenging particularly because of the lack of a current consensus classification system. Systematic central histopathological review of these tumors performed as part of the pediatric collaborative therapeutic protocols has allowed the identification of histologic subtypes with distinct clinical associations. As a result, histopathology has been incorporated within the Children’s Oncology Group (COG) protocols, and only in the United States, as a risk-stratification parameter and for patient management. Therefore, the COG Liver Tumor Committee sponsored an International Pathology Symposium in March 2011 to discuss the histopathology and classification of pediatric liver tumors, and hepatoblastoma in particular, and work towards an International Pediatric Liver Tumors Consensus Classification that would be required for international collaborative projects. Twenty-two pathologists and experts in pediatric liver tumors, including those serving as central reviewers for the COG, European Société Internationale d’Oncologie Pédiatrique, Gesellschaft für Pädiatrische Onkologie und Hämatologie, and Japanese Study Group for Pediatric Liver Tumors protocols, as well as pediatric oncologists and surgeons specialized in this field, reviewed more than 50 pediatric liver tumor cases and discussed classic and newly reported entities, as well as criteria for their classification. This symposium represented the first collaborative step to develop a classification that may lead to a common treatment-stratification system incorporating tumor histopathology. A standardized, clinically meaningful classification will also be necessary to allow the integration of new biological parameters and to move towards clinical algorithms based on patient characteristics and tumor genetics, which should improve future patient management and outcome.

Perivascular epithelioid cell tumor with SFPQ/PSF-TFE3 gene fusion in a patient with advanced neuroblastoma.

We report a case of perivascular epithelioid cell tumor (PEComa) with an SFPQ/PSF-TFE3 gene fusion in a 14-year-old girl treated for adrenal neuroblastoma for 4 years. Imaging studies revealed a tumor in the wall of the sigmoid colon, which was radiologically different from the neuroblastoma, together with several inguinal and cervical lymph node metastases of the neuroblastoma. Microscopically, the tumor in the sigmoid colon showed sheet-like growth of epithelioid cells with abundant clear cytoplasm and round nuclei, which were separated by thin fibrovascular septa. These epithelioid cells were immunohistochemically positive for vimentin, gp100 (detected with monoclonal antibody HMB-45), and TFE3, and the tumor was diagnosed as PEComa. In a fluorescence in situ hybridization assay using an in-house probe for TFE3, the tumor cells showed split signals, indicating a rearrangement of TFE3. Molecular cloning using 5′ rapid amplification of complementary DNA ends and subsequent reverse transcription-polymerase chain reaction revealed an SFPQ/PSF-TFE3 gene fusion. To the best of our knowledge, this is the second reported case of metachronous PEComa subsequent to a primary tumor, and the first report confirming an SFPQ/PSF-TFE3 gene fusion in PEComa.

Aberrations of the hSNF5/INI1 gene are restricted to malignant rhabdoid tumors or atypical teratoid/rhabdoid tumors in pediatric solid tumors

The hSNF5/INI1 gene, which encodes a subunit of the SWI/SNF family of chromatin‐remodeling complexes and is located at 22q11.2, has been reported as a tumor suppressor gene inactivated in malignant rhabdoid tumors (MRTs). We analyzed this gene in varieties of pediatric solid tumors including MRTs, using the reverse transcription‐polymerase chain reaction (PCR) and PCR‐single strand conformation polymorphism method. We found 5 homozygous deletions, 2 truncated mutations, one missense mutation, and one silent mutation of the hSNF5/INI1 gene in 7 MRT cell lines, and one homozygous deletion, one microdeletion, one splicing acceptor site mutation, and one absence of expression in 7 fresh tumor tissues of MRT and atypical teratoid (AT)/rhabdoid tumors (RTs). Homozygous deletions were also found in one (KYM‐1) of 8 rhabdomyosarcoma (RMS) cell lines. To investigate characteristics of the KYM‐1 cell line, we have established KYM‐1 tumors in nude mice into which KYM‐1 cells were transplanted. Notably, we found that MyoD1, known as a marker for RMS, was not expressed in the KYM‐1 cell line as well as MRT cell lines and fresh tumors. Histopathologic, cytogenetic, and molecular studies of the KYM‐1 cell line and KYM‐1 tumors in nude mice have revealed that this RMS cell line should be MRT rather than RMS. RMS‐carrying aberrations of the hSNF5/INI1 gene should be reevaluated. No aberrations of this gene were found in the other 34 cell lines or 80 fresh tumor specimens except the single nucleotide polymorphisms in the 3′ noncoding region. These results suggest that alterations of the hSNF5/INI1 gene were restricted to MRTs or AT/RTs in pediatric solid tumors.

Osteochondromyxoma of bone : A congenital tumor associated with lentigines and other unusual disorders

This article describes the clinical and pathologic features of four unusual bone tumors. Three were congenital or most likely so; the fourth, detected at age 1 year, was probably of considerable duration. The patients, three boys and one girl, each presented with a painless mass. Two had the Carney complex, a familial lentiginous and multiorgan tumorous syndrome; another probably had this disorder; the fourth did not show it, but his mother did. The tumors occurred in the nasal region (n = 2) and the diaphysis of the tibia and radius (n = 1 each). Roentgenographically, three had benign characteristics; the fourth, malignant features. Grossly, the tumors were gelatinous, cartilaginous, and bony. Microscopically, they featured benign-appearing polymorphic cells with few division figures arranged in sheets and lobules set in a myxomatous, cartilaginous, osseous, and hyaline fibrous matrix. Cellularity was low to moderate. The tumors eroded bone, one infiltrated between bony trabeculae, and three had soft tissue extension. Complete resection of one tumor was curative; incomplete excision of two tumors resulted in local recurrence (intracranial and fatal) in one and persistence in the other; the fourth tumor remains under observation after biopsy. No tumor metastasized.