Triethylene glycol dimethacrylate induces large deletions in the hprt gene of V79 cells

Abstract

Acrylate esters are applied in industrial and consumer products often associated with polymers and resins. The difunctional methacrylate, triethylene glycol dimethacrylate (TEGDMA), is also frequently included in dental composite materials. Recently, mutagenicity testing of the compound revealed the induction of gene mutations at the hprt locus in V79 cell [H. Schweikl, G. Schmalz, K. Rackebrandt, The mutagenic activity of unpolymerized resin monomers in Salmonella typhimurium and V79 cells, Mutat. Res. 415 (1998) 119–130]. In the present study, TEGDMA caused a dose dependent increase of the number of micronuclei in V79 cells. Furthermore, the mutation spectra induced in exon sequences of the hprt gene in HPRT-deficient V79 cell clones were analyzed by the polymerase chain reaction (PCR). No DNA sequence deletions were observed in spontaneously occurring HPRT-deficient cell clones at the molecular level after PCR analysis, indicating that all spontaneous mutations were caused by point mutations. However, TEGDMA treated V79 cell cultures exhibited different mutation spectra. Only one cell clone among a total of 25 contained all exon sequences of the hprt gene. Large DNA sequences were deleted in 24 cell clones. Partial gene deletions occurred in four clones from exon 5 through 9, and exon 1 was not amplified in one cell clone. Exon sequences of the hprt gene were totally deleted in 19 HPRT-deficient clones. The induction of mostly large deletions in the genome of mammalian cells, like the mutation spectra induced by TEGDMA in V79 cells here, is probably typical for crosslinking agents, including anticancer drugs. Identical types of mutations including chromosomal aberrations and the formation of micronuclei in vitro were observed for acrylates and methacrylates tested so far in various mutation assays. Therefore, we conclude by analogy that the induction of large DNA sequence deletions as shown here with the reactive dimethacrylate, triethylene glycol dimethacrylate, is probably common for acrylates and methacrylates.