Association of cytogenetic abnormalities in a neuroblastoma and fragile sites expression

Normal expression of fra(3)(p14.2) in lymphocytes of lung cancer patients

Fragile site (FS) analysis was performed in 10 bronchogenic carcinoma families (non-small cell type) each represented by the patient and one adult offspring. Twenty age- and sex-matched controls were evaluated simultaneously for FS expression. The question whether increased fragility at band 3p14 exists in lung cancer patients or their offspring was examined. The expression level was found to be similar among patients, offspring, and controls.

Expression of common fragile sites in untreated non-Hodgkin's lymphoma with aphidicolin and folate deficiency

The frequency and distribution of aphidicolin induced and folate sensitive common fragile sites on chromosomes of peripheral blood lymphocytes in untreated non-Hodgkin's lymphoma patients and healthy controls showed a considerable overlap in the expression of common fragile sites between the two groups. However, a significant increase in the expression of 16 aphidicolin induced common fragile sites was seen in untreated lymphoma patients. In the folate deficient cultures only, the common fragile sites 2q22, 8q24, 11q13, 12q21, 16q22, 17p12 and 20p12 were found in both the groups under study. The fragile sites at 8q22, 8q24, 11q13 and 18q21 in patients showed an increased expression over the control group. Interestingly these fragile sites were located in the same chromosomal bands as the oncogenes, MOS, MYC, BCL-1 and BCL-2 as well as cancer breakpoints specifically associated with non-Hodgkin's lymphoma, suggesting the possibility that fragile sites may play a critical role in the pathogenesis of non-Hodgkin's lymphoma.

Karyotypic abnormalities in benign adrenocortical tumors producing aldosterone

Because familial hyperaldosteronism type II (FH-II) includes tumor formation, we examined the karyotypes of benign adrenocortical aldosterone-producing adenomas (APAs), including those from patients with FH-II. Cell culture was successful in 12 of 14 tumors removed, two of which were from patients with FH-II. Five of the 12 tumors cultured (one from a patient with FH-II) had abnormal karyotypes. All were from male patients, and loss of the Y chromosome was observed in each. One showed loss of chromosome 19, and another showed an unbalanced t(6;7) producing partial trisomy 7q. Oncogenes are present at these breakpoints, and loss of the Y chromosome and monosomy 19 have previously been reported in neoplasia. This is the first report of cytogenetic abnormalities in benign adrenocortical tumors.

Sensitivity to bleomycin and arabinoside cytosine in lymphocytes of patients affected by neuroblastoma and in those of their parents

Chromosomal instability has been described in patients affected by various tumors. We previously reported a high sensitivity to fragile sites induction by aphidicolin in lymphocytes from patients affected by neuroblastoma and in those from their parents. In the search for the most suitable clastogenic agent to enhance the possible differences between healthy controls and patients affected by tumors, we have now tested two other drugs: bleomycin, a radiomimetic agent already used in vitro on chromosomes of patients affected by other tumors and arabinoside cytosine, an inhibitor of DNA polymerases alfa and beta. We observed a high sensitivity to bleomycin both in patients and in their parents, but to arabinoside cytosine only in NB patients. Moreover, the two drugs induced more fragile sites in 1p in patients and in their parents than in healthy controls. This phenomenon, which we already observed after treatment with aphidicolin, might be related to the frequent deletions and loss of heterozigosity in 1p in neuroblastoma cells.

Enhanced expression of 1p32 and 1p22 fragile sites in lymphocytes in cutaneous malignant melanomas

Frequency and distribution of 5-fluorodeoxyuridine (5-FdU) plus caffeine-induced fragile sites on chromosomes of peripheral blood lymphocytes (PBL) from 10 patients with cutaneous melanoma were studied in comparison with 10 PBL samples from normal donors of corresponding sex and age. The total number of breaks showed a significant difference among individuals in both groups, however, the average frequencies of 5-FdU plus caffeine-induced, as well as spontaneous damages in PBL from melanoma patients, were higher than those from healthy volunteers. The analysis of the breakpoint distribution showed a statistically significant increase in the expression of several fragile sites. The highest enhancement was observed at 1p32 and 1p22 sites (p less than 0.001). Earlier, the increase in the expression of 1p32 fragile sites was reported for neuroblastoma patients. We believe that enhanced expression of fragile sites in 1p may play a yet-unknown pathogenetic role in the development of some neuroectodermal tumors.

Cytogenetic and molecular characterization of a newly established neuroblastoma cell line LS

A new human neuroblastoma cell line (LS) that originated from an abdominal tumor of a 16-month-old girl is presented; it was classified, according to Evans, as being stage III. Morphological (dense-core particles) and biochemical characteristics (dopamine-beta-hydroxylase, acetylcholinesterase, neuron-specific-enolase) confirmed the diagnosis. In addition to a slightly variable modal chromosome number of 48 or 49 (because of marker-chromosomes and autosomal trisomies), cytogenetic analysis revealed two constantly appearing chromosomes with homogeneously stained regions (HSR's). The karyotype remained constant over 50 passages in vitro [49,XX, -12, +der5, + 17, + mar1, + mar2]. Double minutes were a rare phenomenon and appeared only in a few metaphases. In situ hybridization showed that some of the HSR's consisted of amplified N-myc copies. The distribution of the N-myc copies according to in situ hybridization signals along the HSR's was compared with the data of Southern and Northern blotting analyses.

Fragile site induction by aphidicolin may be increased in parents of neuroblastoma patients

We recently demonstrated an increased expression of fragile sites, induced by aphidicolin, in lymphocytes of neuroblastoma patients. We have now extended our studies to parents of affected children with neuroblastoma to verify if this characteristic may be genetically transmitted. We have examined 20 families. In most of them, the hypersensitivity to aphidicolin was found in the affected child and in at least one parent. Moreover, some of the parents showed an increase in the expression of the fragile sites 1p32, 1p13, or both that are preferentially expressed in neuroblastoma patients. The possible relations between the hypersensitivity to aphidicolin and the inheritance of predisposition to neuroblastoma must be clarified.

Bleomycin-induced chromosomal damage in tuberous sclerosis

To investigate the possible involvement of mutagen-induced chromosomal instability in tuberous sclerosis the blood lymphocytes obtained from eleven patients with this disease and eleven healthy controls of comparable age and sex were exposed to bleomycin in vitro during the late S and G2 phases of the cell cycle. Neither the spontaneous aberration yields nor the bleomycin-induced chromosomal sensitivity differed between the two groups. The chromosomal distribution of 578 and 478 induced breaks in patients and controls, respectively, was similar. Thus, bleomycin-induced G2 chromosomal hypersensitivity in lymphocytes of patients with tuberous sclerosis is not an intrinsic feature of this hereditary disease.

Common fragile sites and human cancer. A study on lymphocytes from neuroblastoma patients

To clarify the possible relationship between fragile site expression and cancer, we examined lymphocytes from patients affected by neuroblastoma. This neoplasia may be inherited in some cases and is often characterized by a specific chromosomal aberration: deletion of the short arm of chromosome 1. We found a higher expression of fragile sites after aphidicolin and, to a lesser extent, after methotrexate treatment in lymphocytes from neuroblastoma patients as compared with those of normal donors. The analysis of fragile site distribution pointed out the increase in the expression of fragile site 1p32 in the patients. We believe that this finding might be relevant because this fragile site is located in the same region where breakpoints and rearrangements frequently occur in neuroblastoma cells.