Kathleen S. Wilson

Absence of cancer-associated changes in human fibroblasts immortalized with telomerase

The ectopic expression of telomerase in normal human cells results in an extended lifespan, indicating that telomere shortening regulates the timing of cellular senescence. As telomerase expression is a hallmark of cancer, we investigated the long–term effects of forced expression of human telomerase catalytic component (hTERT) in normal human fibroblasts. In vitro growth requirements, cell–cycle checkpoints and karyotypic stability in telomerase–expressing cells are similar to those of untransfected controls. In addition, co–expression of telomerase, the viral oncoproteins HPV16 E6/E7 (which inactivate p53 and pRB) and oncogenic HRAS does not result in growth in soft agar. Thus, although ectopic expression of telomerase in human fibroblasts is sufficient for immortalization, it does not result in changes typically associated with malignant transformation.

High-resolution array CGH identifies common mechanisms that drive embryonal rhabdomyosarcoma pathogenesis

Pediatric rhabdomyosarcoma occurs as two biologically distinct histological variants, embryonal (ERMS) and alveolar (ARMS). To identify genomic changes that drive ERMS pathogenesis, we used a new array comparative genomic hybridization (aCGH) platform to examine a specific subset of ERMS tumors, those occurring in children with clinically defined intermediate‐risk disease. The aCGH platform used has an average probe spacing ∼1 kb, and can identify genomic changes with single gene resolution. Our data suggest that these tumors share a common genomic program that includes inactivation of a master regulator of the p53 and Rb pathways, CDKN2A/B, and activation of FGFR4, Ras, and Hedgehog (Hh) signaling. The CDKN2A/B tumor suppressor is deleted in most patient samples. FGFR4, which encodes a receptor tyrosine kinase, is activated in 20% of tumors, predominantly by amplification of mutant, activating FGFR4 alleles. Over 50% of patients had low‐level gains of a region containing the Hh‐pathway transcription factor GLI1, and a gene expression pattern consistent with Hh‐pathway activation. We also identified intragenic deletions affecting NF1, a tumor suppressor and inhibitor of Ras, in 15% of tumor samples. Deletion of NF1 and the presence of activating Ras mutations (in 42% of patients) were mutually exclusive, suggesting NF1 loss is an alternative and potentially common mechanism of Ras activation in ERMS. Our data suggest that intermediate‐risk ERMS is driven by a common set of genomic defects, a finding that has important implications for the application of targeted therapies to improve the treatment of children diagnosed with this disease.

Renal cell carcinoma with translocation (X;1) Further evidence for a cytogenetically defined subtype

A renal cell carcinoma from a 15-year-old male had a 49,Y,t(X;1)(p11.2;q21), +der(X)t(X;1) (p11.2;q21), +5, -16, +17, +18 karyotype. This is the third report of a translocation involving a breakpoint at Xp11.2 in a renal cell carcinoma in a child. A total of nine cases of renal cell carcinoma involving Xp11, including this case, have been reported. Of the eight cases for which there are genetics reports, all are male. Patients with renal cell carcinoma with abnormalities at Xp11 appear to be younger than renal cell carcinoma patients overall.

HER-2 fluorescence in situ hybridization: results from the survey program of the College of American Pathologists.

CONTEXT Fluorescence in situ hybridization (FISH) is a common method used to determine HER-2 status in breast cancer. Limited information is available concerning reproducibility of FISH in determining HER-2 gene amplification. OBJECTIVE To present proficiency testing results of FISH for HER-2 conducted by the Cytogenetics Resource Committee of the College of American Pathologists/American College of Medical Genetics. DESIGN During the past 5 years, unstained sections from 9 invasive breast carcinomas were used for HER-2 FISH proficiency testing, allowing for comparison of FISH results among a large number of laboratories. Additional data were collected using an educational (ungraded) challenge and supplemental questions in the surveys. RESULTS The number of laboratories participating in HER-2 FISH proficiency testing has increased steadily during the past 5 years (from 35 in 2000 to 139 in 2004). Reproducibility of test results among laboratories was excellent for breast tumors with low copy number (no HER-2 amplification) and for breast tumors with high copy number (HER-2 amplification). However, there was considerable variation in interpretation of results for a tumor with low-level HER-2 amplification that was tested on 2 separate occasions. Responses to supplemental questions indicated that there was a need for consensus on the use of a separate equivocal/borderline interpretative category and the need for standardization of cutoff values used to define interpretative categories. CONCLUSIONS The College of American Pathologists proficiency survey programs provide useful information concerning the reproducibility of clinical testing for HER-2 by FISH and reflect clinical interpretation of HER-2 FISH analyses from laboratories across the country.

Primary effusion lymphomas exhibit complex and recurrent cytogenetic abnormalities

Summary. Cytogenetic findings in a few primary effusion lymphoma (PEL) cell lines have been reported, but only three complete karyotypes of primary specimens from patients with this neoplasm have been published. In this study, cytogenetic analysis was performed on 11 effusion specimens from 10 patients with PEL. We corroborate data obtained from the cell line studies that trisomy 7, trisomy 12 and aberrations in the proximal long arm of chromosome 1 (1q) are recurring cytogenetic aberrations in PEL and also identify breakpoints at 3q23, 7p22, 7q22, 10q24, 12q24, 13q22, 14q24, 14q32, 15p11.2 and Xq22 as well as +8, +15, +19, +X and –Y as recurring chromosome abnormalities. The identification of recurring cytogenetic aberrations may lead to delineation of the genetic events in PEL.

PARK2 copy number aberrations in two children presenting with autism spectrum disorder: further support of an association and possible evidence for a new microdeletion/microduplication syndrome.

Microdeletions of PARK2 have been reported previously in seven patients with autism spectrum disorder. There are no reports of PARK2 microduplications in this population. Presented are two patients, one with deletion and the other with duplication, both with autism spectrum disorder, though their syndromic phenotypes vary. The deletion patient is cognitively normal and ectomorphic: the duplication patient is cognitively impaired, underweight and short. Further, the microduplication patient has demonstrated adverse medication reactions to psychotropic medications active in the dopamine metabolic pathway: cyclopentolate, lisdexamfetamine, methylphenidate. These patients support an association between PARK2 mutations and autism spectrum disorder and suggest that duplications may be equally causative. It is hypothesized that the disparate patient phenotypes may represent a deletion/duplication syndrome and that the adverse medication reactions may be a pharmacogenetic phenomenon.

Translocation (4;19)(q35;q13.1)–Associated Primitive round Cell Sarcoma: Report of a Case and Review of the Literature:

We report the 4th case of a primitive round cell sarcoma with the translocation (4;19)(q35;q13.1) as the primary cytogenetic abnormality. This undifferentiated sarcoma shows some features of Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), including a diffuse reactivity for FLI1, but it shows only focal and weak reactivity for CD99 and is negative for a rearrangement of EWS, the molecular signature of ES/PNET. Recognition of the histopathologic and cytogenetic features of this entity is necessary to avoid its misdiagnosis as ES/PNET, especially in small biopsy samples.

The family pet as an unlikely source of group A beta-hemolytic streptococcal infection in humans

This study examines the possibility of the family pet serving as a reservoir for group A betahemolytic streptococcal infections in humans. We obtained oropharyngeal cultures from children with acute pharyngitis and concurrent oropharyngeal cultures from their household pets. Children with culture-proved group A betahemolytic streptococcal pharyngitis were detected in 26 of 42 households surveyed. Oropharyngeal cultures were also collected from a group of children without pharyngitis and their pets. Additionally 149 dogs and cats from a local veterinary hopsital were cultured from 371 body sites including the oropharynx, axilla and vagina. All beta-hemolytic bacterial isolates were identified by colonial and microscopic morphology, catalase and pyrrolidonylarylamidase production, bacitracin susceptibility and serogrouping. No group A beta-hemolytic streptococci were recovered from any of the body sites surveyed from a total of 230 animals. Based on these findings, the family pet seems to be an unlikely reservoir for group A beta-hemolytic streptococci.

Malignant transformation of non-neoplastic Barrett's epithelial cells through well-defined genetic manipulations.

Background Human Barretts cancer cell lines have numerous, poorly-characterized genetic abnormalities and, consequently, those lines have limited utility as models for studying the early molecular events in carcinogenesis. Cell lines with well-defined genetic lesions that recapitulate various stages of neoplastic progression in Barretts esophagus would be most useful for such studies. Methodology/Principal Findings To develop such model cell lines, we started with telomerase-immortalized, non-neoplastic Barretts epithelial (BAR-T) cells, which are spontaneously deficient in p16, and proceeded to knock down p53 using RNAi, to activate Ras by introducing oncogenic H-RasG12V, or both. BAR-T cells infected with either p53 RNAi or oncogenic H-RasG12V alone maintained cell-to-cell contact inhibition and did not exhibit anchorage-independent growth in soft agar. In contrast, the combination of p53 RNAi knockdown with expression of oncogenic H-RasG12V transformed the p16-deficient BAR-T cells, as evidenced by their loss of contact inhibition, by their formation of colonies in soft agar, and by their generation of tumors in immunodeficient mice. Conclusions/Significance Through these experiments, we have generated a number of transformed and non-transformed cell lines with well-characterized genetic abnormalities recapitulating various stages of carcinogenesis in Barretts esophagus. These lines should be useful models for the study of carcinogenesis in Barretts esophagus, and for testing the efficacy of chemopreventive and chemotherapeutic agents.

Case report of a 22-week fetus with 47,XXX karyotype and multiple lower mesodermal defects

ABSTRACT A 22-week stillborn fetus with 47,XXX karyotype had lower mesodermal defects consisting of irregular fusion of the sacral vertebrae, anal agenesis, multicystic dysplasia of a horseshoe kidney, a single umbilical artery, dysplastic ovaries, and uterine hypoplasia. This case provides additional evidence for an association between trisomy X and genitourinary defects including lower mesodermal defects sequence.