title: Molecular basis of carcinogenicity of tungsten alloy particles.
abstract: The tungsten alloy of 91% tungsten, 6% nickel and 3% cobalt (WNC 91-6-3) induces rhabdomyosarcoma when implanted into a rat thigh muscle. To investigate whether this effect is species-specific human HSkMc primary muscle cells were exposed to WNC 91-6-3 particles and responses were compared with those from a rat skeletal muscle cell line (L6-C11). Toxicity was assessed by the adenylate kinase assay and microscopy, DNA damage by the Comet assay. Caspase 3 enzyme activity was measured and oligonucleotide microarrays were used for transcriptional profiling. WNC 91-6-3 particles caused toxicity in cells adjacent to the particles and also increased DNA strand breaks. Inhibition of caspase 3 by WNC 91-6-3 occurred in rat but not in human cells. In both rat and human cells, the transcriptional response to WNC 91-6-3 showed repression of transcripts encoding muscle-specific proteins with induction of glycolysis, hypoxia, stress responses and transcripts associated with DNA damage and cell death. In human cells, genes encoding metallothioneins were also induced, together with genes related to angiogenesis, dysregulation of apoptosis and proliferation consistent with pre-neoplastic changes. An alloy containing iron, WNF 97-2-1, which is non-carcinogenic in vivo in rats, did not show these transcriptional changes in vitro in either species while the corresponding cobalt-containing alloy, WNC 97-2-1 elicited similar responses to WNC 91-6-3. Tungsten alloys containing both nickel and cobalt therefore have the potential to be carcinogenic in man and in vitro assays coupled with transcriptomics can be used to identify alloys, which may lead to tumour formation, by dysregulation of biochemical processes.
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Harris
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Tim D
authors.initials: TD
authors.lastname: Williams
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Rosemary H
authors.initials: RH
authors.lastname: Waring
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. Electronic address: n.hodges@bham.ac.uk.
authors.forename: Nikolas J
authors.initials: NJ
authors.lastname: Hodges
mesh_terms: D000328:Adult; D000497:Alloys / Q000633:toxicity*; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors / Q000633:toxicity; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020552:Comet Assay; D053960:DNA Breaks; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D018570:Risk Assessment; D013045:Species Specificity; D014158:Transcription, Genetic; D017973:Tungsten Compounds / Q000633:toxicity*
chemical_list: D000497:Alloys; D061945:Caspase Inhibitors; D009124:Muscle Proteins; D017973:Tungsten Compounds; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: Carcinogen; Cobalt; Nickel; Rhabdomyosarcoma; Transcriptomics; Tungsten