DICER1 mutations in familial multinodular goiter with and without ovarian Sertoli-Leydig cell tumors.

Context: Nontoxic multinodular goiter (MNG) is frequently observed in the general population, but little is known about the underlying genetic susceptibility to this disease. Familial cases of MNG have been reported, and published reports describe 5 families that also contain at least 1 individual with a Sertoli-Leydig cell tumor of the ovary (SLCT). Germline mutations in DICER1, a gene that codes for an RNase III endoribonuclease, have been identified in families affected by pleuropulmonary blastoma (PPB), some of whom include cases of MNG and gonadal tumors such as SLCTs.

Paraganglioma, neuroblastoma, and a SDHB mutation: Resolution of a 30-year-old mystery.

Familial paraganglioma/pheochromocytoma (PGL/PCC) is genetically heterogenous with mutations in three of the four subunits of the heterotetrameric mitochondrial complex II enzyme succinate dehydrogenase (SDH) being causally responsible for the majority of cases. In addition to PGL/PCC an array of non-paraganglial tumors have been described in affected individuals. We present a 30-year follow-up on the family of a deceased patient who synchronously developed malignant neuroblastoma (NBL), PCC, and renal cell carcinoma (RCC).

The Hunter-MacDonald syndrome with expanded phenotype including risk of meningioma: an update and review.

Hunter-MacDonald syndrome (HMS) is a rare, autosomal dominant skeletal dysplasia with multiple malformations. The skeletal manifestations of HMS include short stature, scoliosis, epiphyseal dysplasia with early osteoarthritis leading to joint replacement, prominent humeral insertions for the deltoids, camptodactyly, subluxation of the thumbs, and malformed feet. Craniofacial manifestations include normal head circumference, tall forehead, bitemporal narrowing, ptosis, short palpebral fissures, and short philtrum.

An unusual sellar mass--solitary plasmacytoma.

Objective: To describe a case of solitary intrasellar plasmacytoma in a patient with a preoperative diagnosis of a nonfunctioning pituitary adenoma.

Methods: A case of a solitary intrasellar plasmacytoma is presented, in which the clinical and laboratory findings are detailed and the response to treatment is discussed. Pertinent reports from the literature are reviewed.

Clinical and molecular delineation of the Greig cephalopolysyndactyly contiguous gene deletion syndrome and its distinction from acrocallosal syndrome.

Greig cephalopolysyndactyly syndrome (GCPS) is caused by haploinsufficiency of GLI3 on 7p13. Features of GCPS include polydactyly, macrocephaly, and hypertelorism, and may be associated with cognitive deficits and abnormalities of the corpus callosum. GLI3 mutations in GCPS patients include point, frameshift, translocation, and gross deletion mutations.

Two distinct phenotypes caused by two different missense mutations in the same codon of the VHL gene.

We have identified a family segregating von Hippel-Lindau (VHL) disease with a previously unreported T547A mutation in exon 1 of the VHL gene that causes a Tyr112 to Asn missense alteration in the protein. The mutation was identified by nucleotide sequencing and confirmed by restriction enzyme digestion. The mutation cosegregated with the disease in all five tested affected individuals from the extended family.

Inhibition of apoptosis by overexpressing Bcl-2 enhances gene amplification by a mechanism independent of aphidicolin pretreatment.

To study the effect of apoptosis on gene amplification, we have constructed HeLa S3 cell lines in which the expression of bcl-2 (BCL2) can be controlled by tetracycline in the growth medium. Induction of Bcl-2 expression caused a temporary delay of apoptosis and resulted in roughly a 3-fold increase in the frequency of resistant colonies when cells were selected with trimetrexate. This resistance was due to amplification of the dihydrofolate reductase gene.

Tetracycline-controlled gene expression system achieves high-level and quantitative control of gene expression.

The tetracycline-controlled gene expression system utilizes the control elements of the tetracycline resistance operon encoded in TnlO of Escherichia coli to control gene expression in eukaryotic cells. Here we demonstrate the quantitative control of the expression of the luciferase gene, dihydrofolate reductase gene, and bcl-2 gene in HeLa S3 or Chinese hamster ovary AA8 cells using the tetracycline-controlled gene expression system. Regardless of the host cell lines or the genes being expressed, there is a common range of tetracycline concentration within which the expression of genes is most sensitively regulated.

P-glycoprotein confers methotrexate resistance in 3T6 cells with deficient carrier-mediated methotrexate uptake.

P-glycoprotein (Pgp), a transmembrane efflux pump encoded by the MDR1 gene, transports various lipophilic drugs that enter the cell by passive diffusion through the lipid bilayer. Pgp-expressing multidrug-resistant cell lines are not usually cross-resistant to a hydrophilic antifolate methotrexate (MTX). MTX enters cells primarily through a folate carrier, but passive diffusion becomes the primary mode of MTX uptake in carrier-deficient cells.

BCL-2 expression delays drug-induced apoptosis but does not increase clonogenic survival after drug treatment in HeLa cells.

Apoptosis is a major form of cell death induced by chemotherapeutic drugs. Overexpression of the proto-oncogene bcl-2 can prevent apoptosis in various types of cells. We have constructed a HeLa S3 cell line in which the expression of bcl-2 can be controlled by the concentration of tetracycline in the medium.

Dissociation of nuclear and cytoplasmic cell cycle progression by drugs employed in cell synchronization.

We have studied the effect of the cell synchronization agents compactin, ciclopirox olamine, mimosine, aphidicolin, ALLN, and colcemid on several parameters of cell cycle progression in mitotically synchronized HeLa S3 cells. Using cell size and cyclin A and B levels as markers of cytoplasmic progression and DNA content as a measure of nuclear cell cycle position, we have examined coordination of cytoplasmic and nuclear events during induction synchrony. Each synchronizing agent was unique in its effect on the coordination of the cytoplasmic and nuclear cycle.

Genetic and biochemical normalization in female carriers of Duchenne muscular dystrophy: evidence for failure of dystrophin production in dystrophin-competent myonuclei.

We studied 19 symptomatic female carriers of the Duchenne muscular dystrophy (DMD) gene. Most of these dystrophinopathy patients had had an erroneous or ambiguous diagnosis prior to dystrophin immunofluorescence testing. We assessed clinical severity by a standardized protocol, measured X-chromosome inactivation patterns in blood and muscle DNA, and quantitated the dystrophin protein content of muscle.

Human cDNA clones that modify radiomimetic sensitivity of ataxia-telangiectasia (group A) cells.

Genes responsible for genetic diseases with increased sensitivity to DNA-damaging agents can be identified using complementation cloning. This strategy is based on in vitro complementation of the cellular sensitivity by gene transfer. Ataxia-telangiectasia (A-T) is a multisystem autosomal recessive disorder involving cellular sensitivity to ionizing radiation and radiomimetic drugs.

Induction of apoptosis by the anti-tubulin drug colcemid: relationship of mitotic checkpoint control to the induction of apoptosis in HeLa S3 cells.

We have studied the relationship between apoptosis and drug-induced cell cycle perturbation in HeLa S3 cells when treated with the anti-tubulin drug colcemid. We found that at least two distinct mechanisms contributed to colcemid cytotoxicity and apoptosis. Continuous exposure to concentrations of colcemid sufficient to block cells at the mitotic checkpoint led to the appearance of apoptotic cells approximately one cell cycle after their initial accumulation in mitosis.

Heterogeneity in the mitotic checkpoint control of BALB/3T3 cells and a correlation with gene amplification propensity.

Chinese hamster ovary (and many rodent cell lines) transiently delay mitosis and progress into a second cell cycle without undergoing cytokinesis when treated with Colcemid, whereas HeLaS3 (and most human cell lines) arrest permanently in mitosis. We have discussed these differences and their consequences for cell survival under cell cycle-perturbing conditions within the context of mitotic checkpoint control (Schimke et al., Cold Spring Harbor Symp.

Life, death and genomic change in perturbed cell cycles.

HeLaS3 cells undergo apoptosis after 18-24 h of cell cycle stasis irrespective of the agent employed (colcemid, aphidicolin, cis-platin). At high drug concentrations apoptosis occurs in cells arrested in the cell cycle in which the drug is applied and at a cell cycle position dependent on the mechanism of drug action. At low concentrations (or short exposure times) cells undergo apoptosis after progressing through an aberrant mitosis and only after 18 h of cell cycle stasis in a 'pseudo G1/S' cell cycle position.

Detection of new paternal dystrophin gene mutations in isolated cases of dystrophinopathy in females.

Duchenne muscular dystrophy is one of the most common lethal monogenic disorders and is caused by dystrophin deficiency. The disease is transmitted as an X-linked recessive trait; however, recent biochemical and clinical studies have shown that many girls and women with a primary myopathy have an underlying dystrophinopathy, despite a negative family history for Duchenne dystrophy. These isolated female dystrophinopathy patients carried ambiguous diagnoses with presumed autosomal recessive inheritance (limb-girdle muscular dystrophy) prior to biochemical detection of dystrophin abnormalities in their muscle biopsy.

Cyclin B1 expression in HeLa S3 cells studied by flow cytometry.

Using a procedure to stain cells simultaneously for cyclin B1 protein and DNA, we have examined cyclin B1 expression by flow cytometry in human cells under a variety of perturbing and nonperturbing conditions. The method described is useful for measuring relative differences in cyclin B level (immunochemically detectable epitope) as a function of cell cycle position on an individual cell basis and thus to examine cell cycle-related changes in cyclin B expression without prior cell synchronization. We show that in HeLaS3 cells, cyclin B1 accumulates in cells only after they become 4C and have resided in G2 for a short period of time.

The propensity for gene amplification: a comparison of protocols, cell lines, and selection agents.

We have studied cell lines of rodent and human origin for their propensity to become resistant to antifolates (methotrexate, trimetrexate), phosphonacetyl-L-aspartate (PALA), and colcemid, resistances associated with amplification of the DHFR, CAD, and MDR1 genes, respectively. We have employed two different methods: (1) a shallow step-wise selection protocol, where time to attain specified resistance is the quantitative measure, (2) the frequency of resistant colonies at specified drug concentrations. Although there are advantages and disadvantages to both methods, the two methods gave the same relative ranking of cell lines.