Investigation of the cytotoxic effects of DNA damaging agents on neurofibromatosis cells

Cellular radiosensitivity of patients with different types of neurofibromatosis

Skin fibroblast cell strains were developed from nine Saudi patients with different types of neurofibromatosis (NF) and nine healthy subjects (controls), and their radiosensitivity was compared following chronic exposure to gamma-radiation at a dose rate of 0.0076 Gy/min (1 Gy = 100 rads). Cells from both normal appearing skin and café-au-lait spots of the different NF patients (7 out of 9) clearly showed increased radiosensitivity, with D10 (dose resulting in 10% survival) values of 2.0-4.4 Gy for the former and 3.0-4.8 Gy for the latter, compared to the normal controls (with D10 values of 6.1-10.6 Gy). These data provide further evidence of an association of enhanced cellular sensitivity to chronic irradiation with NF regardless of the classes they belong to. Hypersensitivity to specific carcinogens may, thus, be a factor responsible for the increased propensity to cancer in these patients.

Spontaneous and induced levels of chromosomal aberration and sister-chromatid exchange in neurofibromatosis: no evidence of chromosomal hypersensitivity

Chromosomal aberration (CA) and sister-chromatid exchange (SCE) frequencies have been assessed in 9 patients with von Recklinghausen's neurofibromatosis (NF1) and 8 apparently healthy controls. In separate experiments over a 5-year period, blood lymphocytes, skin fibroblast cell strains, and lymphoblastoid lines from both groups were treated with X-rays or mitomycin C (MMC) to determine whether the NF1 group was more sensitive to these agents than the control group. No difference between cells from NF1 patients and controls was observed with respect to spontaneous or X-ray-induced CA. Spontaneous or X-ray- and MMC-induced SCE frequencies were also similar in NF1 patients and controls.

The transformed (initiated) human cell phenotype: study of cultured skin fibroblasts from individuals predisposed to cancer

The present study demonstrated the expression of abnormal phenotypes (biomarkers) in cultured skin fibroblasts from hereditary adenomatosis of the colon and rectum (ACR) and neurofibromatosis (NF) patients. These biomarkers occur systemically and they include cytoskeletal structures, cytotoxicity and sensitivity to transformation by oncogenic agents, expression of transformation-associated antigen, and effects by a tumor promoter. Collectively, these biomarkers define the transformed (initiated) human cell phenotype, as determined through use of cultured skin fibroblasts that were obtained from individuals at risk of cancer. In conjunction with clinical signs, these biomarkers can be used to determine gene expression and gene penetrance. Extension of these studies in the form of a multiparameter matrix may permit the early detection of cancer.

Cell culture study on neurofibromatosis

Cells obtained on culture from normal appearing skin (NFns) and from neurofibromas of neurofibromatosis patients (NFnf), and from normal skin of normal donors (Normal) were studied. We measured the growth rate, maximal cell density, radiation sensitivity and resistance to 3-nitrotyrosine of each of the three groups of strains. The growth rate and maximal cell density of fibroblasts derived from neurofibromas of the neurofibromatosis patients were significantly lower than those in normal donors. The neurofibromatosis cells showed no X-ray hypersensitivity, as compared to normal controls. We also did not observe resistance to 3-nitrotyrosine of the cells derived from normal appearing skin of the neurofibromatosis patients. However, cells derived from neurofibromas of the neurofibromatosis patients showed resistance to 3-nitrotyrosine. This phenomenon may explain the slow growth rate of the latter cells.