Monosomy 6 in human cultured fibroblast-like cells after long-term stimulation with acidic fibroblast growth factor (FGF1)

Abstract

Long-term exposure to fibroblast growth factor type 1 (FGFl) of fibroblast-like cells derived from neurofibromas of patients with neurofibromatosis type 1, from angiofibromas of patients with tuberous sclerosis, and from foreskin of unaffected donors resulted in the outgrowth of monosomy 6 in 7 out of 14 cell lines examined. After their initial detection by cytogenetic analysis, the proportion of cells which had lost one chromosome 6 was monitored by FISH using α-satellite probes specific for chromosome 6 and 7, and by PCR analysis of polymorphic microsatellite markers. Monosomy 6 exceeding baseline levels developed only in cultures exposed to FGF1, and the emergence of monosomic cells could not be correlated with a given donor’s genotype. During serial culture, the proportion of monosomic cells increased to over 90 % in 5 of the 7 affected strains. A conspicuous change of cellular morphology from spindle-shaped to more epithelial-type cells was noted in monosomic cultures, even though none of them converted to a permanent cell line during the observation period. We conclude that long-term exposure of human fibroblast-like cell strains to FGFl results in the emergence of monosomy 6 in 50% of the cultures so treated. A selective advantage for such monosomic cells is the most likely explanation for their steady increase during serial culture.

Monosomy 6 in human cultured fibroblast-like cells permanently stimulated by fibroblast growth factor 1: evidence for selection

“…In our previous study, 7 of 14 lines of human FLCs responded to permanent stimulation with FGF1 by developing increasing subpopulations of mono6 cells (Krone et al, 1997). These findings prompted us to examine additional FLC lines, six of which have meanwhile achieved a cumulative number of cell population doublings (CPDs) comparable with those of the lines previously investigated.…”

“…Some of the experiments were performed with a foreskin-derived (C2) and an angiofibroma-derived (TS2) line that had been studied in our previous investigation (Krone et al, 1997).…”

“…In some cases, 1:2 splits were employed. Details of the procedure for the determination of cumulative cell population doublings (CPDs) were described previously (Krone et al, 1997). Standard techniques were used for chromosome preparations; G-banding by staining with DAPI and subsequent image processing served for chromosome identification.…”

“…FISH was performed with either a biotin-labeled chromosome painting probe for chromosome 6 or with a combination of ·-satellite probes specific for chromosomes 6 (D6Z1) and 7 (D7Z1), as described previously (Krone et al, 1997). As a rule, at least 200 nuclei were analyzed in each FISH experiment.…”

“…In the course of our studies on the response of human fibroblast-like cells (FLCs) to long-term stimulation with acidic fibroblast growth factor (FGF1), we observed the emergence of morphologically altered cells that exhibited increasing portions of cells with monosomy 6 (mono6 cells) toward the end of their in vitro lifespan in 7 of 14 lines grown in the presence of FGF1 (Krone et al, 1997). None of these lines has immortalized.…”