A Carcinogen-induced mouse model recapitulates the molecular alterations of human muscle invasive bladder cancer.

The N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) mouse model is an attractive model system of muscle-invasive bladder cancer (MIBC) as it recapitulates the histology of human tumors in a background with intact immune system. However, it was unknown whether this carcinogen-induced model also mimicked human MIBC at the molecular and mutational level. In our study, we analyzed gene expression and mutational landscape of the BBN model by next-generation sequencing followed by a bioinformatic comparison to human MIBC using data from The Cancer Genome Atlas and other repositories. BBN tumors showed overexpression of markers of basal cancer subtype, and had a high mutation burden with frequent Trp53 (80%), Kmt2d (70%), and Kmt2c (90%) mutations by exome sequencing, similar to human MIBC. Many variants corresponded to human cancer hotspot mutations, supporting their role as driver mutations. We extracted two novel mutational signatures from the BBN mouse genomes. The integrated analysis of mutation frequencies and signatures highlighted the contribution of aberrations to chromatin regulators and genetic instability in the BBN tumors. Together, our study revealed several similarities between human MIBC and the BBN mouse model, providing a strong rationale for its use in molecular and drug discovery studies.

Facial intramuscular lipoma occurrence following topical cosmetic injection with a mixture of basic fibroblast growth factor: A report of two cases.

Growth factors and cytokines control cell growth, proliferation and differentiation via a network of inter- and intracellular signalling pathways, and are involved in skin self-renewing and wound healing. In recent years, topical and injectable growth factors and cytokines have emerged as an intriguing therapeutic modality that can be harnessed for aesthetic purposes. However, very little data are available on their long-term safety and tolerability. In this report, we describe two cases of patients, who developed intramuscular lipoma of the chin following topical injection with a mixture of basic fibroblast growth factor as the main ingredients for chin augmentation. Biopsies in the two cases were performed at our department, and revealed intramuscular lipoma. Our report indicates that the topical injection of growth factors can lead to tumorigenesis, so health care providers need to be aware of its potential consequences.

Induction of rhabdomyosarcoma by embedded military-grade tungsten/nickel/cobalt not by tungsten/nickel/iron in the B6C3F1 mouse.

Continued improvements in the ballistic properties of military munitions have led to metal formulations for which little are known about the long-term health effects. Previously we have shown that a military-grade tungsten alloy comprised of tungsten, nickel, and cobalt, when embedded into the leg muscle of F344 rats to simulate a fragment wound, induces highly aggressive metastatic rhabdomyosarcomas. An important follow-up when assessing a compound's carcinogenic potential is to test it in a second rodent species. In this study, we assessed the health effects of embedded fragments of 2 military-grade tungsten alloys, tungsten/nickel/cobalt and tungsten/nickel/iron, in the B6C3F1 mouse. Implantation of tungsten/nickel/cobalt pellets into the quadriceps muscle resulted in the formation of a rhabdomyosarcoma around the pellet. Conversely, implantation of tungsten/nickel/iron did not result in tumor formation. Unlike what was seen in the rat model, the tumors induced by the tungsten/nickel/cobalt did not exhibit aggressive growth patterns and did not metastasize.

In vivo corrosion, tumor outcome, and microarray gene expression for two types of muscle-implanted tungsten alloys.

Tungsten alloys are composed of tungsten microparticles embedded in a solid matrix of transition metals such as nickel, cobalt, or iron. To understand the toxicology of these alloys, male F344 rats were intramuscularly implanted with pellets of tungsten/nickel/cobalt, tungsten/nickel/iron, or pure tungsten, with tantalum pellets as a negative control. Between 6 and 12 months, aggressive rhabdomyosarcomas formed around tungsten/nickel/cobalt pellets, while those of tungsten/nickel/iron or pure tungsten did not cause cancers. Electron microscopy showed a progressive corrosion of the matrix phase of tungsten/nickel/cobalt pellets over 6 months, accompanied by high urinary concentrations of nickel and cobalt. In contrast, non-carcinogenic tungsten/nickel/iron pellets were minimally corroded and urinary metals were low; these pellets having developed a surface oxide layer in vivo that may have restricted the mobilization of carcinogenic nickel. Microarray analysis of tumors revealed large changes in gene expression compared with normal muscle, with biological processes involving the cell cycle significantly up-regulated and those involved with muscle development and differentiation significantly down-regulated. Top KEGG pathways disrupted were adherens junction, p53 signaling, and the cell cycle. Chromosomal enrichment analysis of genes showed a highly significant impact at cytoband 7q22 (chromosome 7) which included mouse double minute (MDM2) and cyclin-dependant kinase (CDK4) as well as other genes associated with human sarcomas. In conclusion, the tumorigenic potential of implanted tungsten alloys is related to mobilization of carcinogenic metals nickel and cobalt from corroding pellets, while gene expression changes in the consequent tumors are similar to radiation induced animal sarcomas as well as sporadic human sarcomas.

Isolation and characterization of a novel noncoding RNA from nickel-induced lung cancer.

Noncoding RNAs have drawn significant attention in carcinogenesis. In this study, we identified a novel gene named nickel-related gene1 (NRG1) associated with nickel-induced cancer. By using rapid amplification of cDNA end PCR, we obtained the full length of the cDNA. The sequence was analyzed by using related bioinformatics software and comparative genomics methods. The results showed that NRG1 was located on chromosome 2q12, within intron2 of ADAMTS6, a disintegrin and metalloproteinase with thrombospondin motifs. And, NRG1 had a high level of homology (76 %) to rat LINE1 sequence RL1.3 (long interspersed middle repetitive DNA). What's more, there was no continuous open reading frame present in NRG1 sequence. Taken together, these data demonstrate that NRG1 is a novel noncoding RNA, and we predicted it may be a transposon-like gene. The identification of NRG1 emphasized the potential role of noncoding RNA in nickel carcinogenesis.

Muscle sarcomas and alopecia in A/J mice chronically treated with nicotine.

AIMS: To evaluate the pathobiologic effects of long-term treatment with nicotine of A/J mice susceptible to tobacco-induced lung carcinogenesis. MAIN METHODS: Experimental group of mice received subcutaneous injections of the LD(50) dose of (-)nicotine hydrogen tartrate of 3 mg/kg/day, 5 days per week for 24 months, and control group received the vehicle phosphate-buffered saline. KEY FINDINGS: Nicotine treated mice, 78.6%, but none of control of mice, developed neoplasms originating from the uterus or skeletal muscle. Examination of the uterine neoplasms revealed leiomyosarcomas, composed of whorled bundles of smooth-muscle like cells with large and hyperchromatic nuclei. Sections of the thigh neoplasms revealed densely cellular tumors composed of plump spindle cells, with occasional formation of 'strap' cells, containing distorted striations. Both neoplasms were positive for desmin staining. A solitary pulmonary adenoma with papillary architecture also occurred in one nicotine treated mouse. Experimental mice also developed transient balding starting as small patches of alopecia that progressed to distinct circumscribed areas of complete hair loss or large areas of diffuse hair loss. SIGNIFICANCE: We demonstrate for the first time that chronic nicotine treatment can induce the development of muscle sarcomas as well as transient hair loss. These findings may help explain the association of childhood rhabdomyosarcoma with parental smoking and earlier onset of balding in smokers. It remains to be determined whether the pathobiologic effects of nicotine result from its receptor-mediated action and/or its tissue metabolites cotinine and N'-nitrosonornicotine, or toxic effects of reactive oxygen species activated due to possible intracellular accumulation of nicotine.

Methylation of RAR-ß2, RASSF1A, and CDKN2A genes induced by nickel subsulfide and nickel-carcinogenesis in rats.

OBJECTIVE: To investigate the expression variation of RAR-ß2, RASSF1A, and CDKN2A gene in the process of nickel-induced carcinogenesis. METHODS: Nickel subsulfide (Ni(3)S(2)) at dose of 10 mg was given to Wistar rats by intramuscular injection. The mRNA expression of the three genes in induced tumors and their lung metastasis were examined by Real-time PCR. The methylation status of the 5' region of these genes were detected by Quantitative Real-time methylation specific PCR. RESULTS: The mRNA expressions of the three genes both in muscle and lung tumor were decreased distinctly in comparison with normal tissue. But hypermethylation was found only in muscle tumor. CONCLUSION: These findings suggest that loss of function or decrease of RAR-ß2, RASSF1A, and CDKN2A, as well as the hypermethylation of 5' region of these genes, are related with nickel exposure.

Specific clones of spontaneously evolving karyotypes generate individuality of cancers.

Several researchers, including us, have recently proposed that specific karyotypes, rather than specific mutations, generate the "biochemical individuality" of cancers, defined by individual growth rates, metabolisms, drug-resistances, metastases and cell morphologies. According to our theory, independent karyotypic evolutions generate cancers, much like new phylogenetic species. To allow such evolutions in the lifetime of an organism, the normal karyotype must be destabilized, but not the genes. The karyotype is destabilized by aneuploidy, because aneuploidy unbalances conserved teams of proteins that segregate, synthesize and repair chromosomes. And aneuploidy is induced either by carcinogens or spontaneously. Here, we tested this theory using a new system that virtually excludes spontaneous mutation. In this sytem, 50% of normal human muscle cells became aneuploid and 5 per 10(6) formed foci of transformed Mu6 cells - only 2 months after transfection with 6 virus-activated cellular genes. Analyses of 10 foci revealed: (1) clonal karyotypes, consisting of one or more stemlines of spontaneously evolving aneuploidies and some non-clonal aneuploidies, and (2) individual phenotypes, such as cell morphologies, growth rates and intrinsic resistance to cytosine arabinoside, shared by 5 foci with a common stemline. Due to the short preneoplastic latencies of Mu6 cells several non-clonal precursors of focus-specific, aneuploid karyotypes were detectable before focus formation. Chemical carcinogens were also found to induce tumors with clonally evolving stemlines in Chinese hamsters. We conclude that specific clones of spontaneously evolving karyotypes, rather than specific mutations, generate the individuality of cancers. This answers the age-old question, why even cancers of the same kind do not have consistent karyotypes.

Embedded weapons-grade tungsten alloy shrapnel rapidly induces metastatic high-grade rhabdomyosarcomas in F344 rats.

Continuing concern regarding the potential health and environmental effects of depleted uranium and lead has resulted in many countries adding tungsten alloy (WA)-based munitions to their battlefield arsenals as replacements for these metals. Because the alloys used in many munitions are relatively recent additions to the list of militarily relevant metals, very little is known about the health effects of these metals after internalization as embedded shrapnel. Previous work in this laboratory developed a rodent model system that mimicked shrapnel loads seen in wounded personnel from the 1991 Persian Gulf War. In the present study, we used that system and male F344 rats, implanted intramuscularly with pellets (1 mm times 2 mm cylinders) of weapons-grade WA, to simulate shrapnel wounds. Rats were implanted with 4 (low dose) or 20 pellets (high dose) of WA. Tantalum (20 pellets) and nickel (20 pellets) served as negative and positive controls, respectively. The high-dose WA-implanted rats (n = 46) developed extremely aggressive tumors surrounding the pellets within 4-5 months after implantation. The low-dose WA-implanted rats (n = 46) and nickel-implanted rats (n = 36) also developed tumors surrounding the pellets but at a slower rate. Rats implanted with tantalum (n = 46), an inert control metal, did not develop tumors. Tumor yield was 100% in both the low- and high-dose WA groups. The tumors, characterized as high-grade pleomorphic rhabdomyosarcomas by histopathology and immunohistochemical examination, rapidly metastasized to the lung and necessitated euthanasia of the animal. Significant hematologic changes, indicative of polycythemia, were also observed in the high-dose WA-implanted rats. These changes were apparent as early as 1 month postimplantation in the high-dose WA rats, well before any overt signs of tumor development. These results point out the need for further studies investigating the health effects of tungsten and tungsten-based alloys.

Reduced Fhit protein expression in nickel-transformed mouse cells and in nickel-induced murine sarcomas.

Nickel compounds are carcinogenic and induce malignant transformation of cultured cells. Since nickel has low mutagenic potential, it may act predominantly through epigenetic mechanisms, including down-regulation of tumor suppressor genes. FHIT is a tumor suppressor gene whose expression is frequently reduced or lost in tumors and pre-malignant lesions. Previously, we have shown that the phosphohydrolase activity of Fhit protein, associated with its tumor suppressor action, is inhibited by nickel. In cells, such effect would assist in carcinogenesis. The latter could be further enhanced if nickel also lowered cellular levels of Fhit protein itself, e.g. by down-regulation of FHIT gene. To test this possibility, we determined Fhit protein and Fhit-mRNA levels in a nickel-transformed mouse cell line and in nickel-induced murine sarcomas. In B200 cells, derived by nickel treatment of BALB/c-3T3 cells and exhibiting a malignant phenotype, Fhit protein levels were 50% of those in the parental cells, while Fhit-mRNA expression remained unchanged. A decrease of up to > 90% in Fhit protein levels was also observed in 22 local sarcomas (mostly fibrosarcomas) induced by i.m. injection of nickel subsulfide in C57BL/6 and MT+ (C57BL/6 overexpressing metallothionein) mice, as compared with normal muscles. Moreover, Fhit was absent in 3 out of 10 sarcomas from MT+ mice and in 1 of 12 sarcomas from C57BL/6 mice. The lack of Fhit protein coincided with the absence of the Fhit-mRNA transcript in these tumors. However, in the other tumors, the decreased Fhit levels were not always accompanied by reduced expression of Fhit-mRNA. Thus, the observed lowering of Fhit protein levels is mostly associated with changes in mRNA expression and protein translation or turnover rates, and rarely with a full silencing of the gene itself. Overall, the decline of Fhit in cells or tissues malignantly transformed by nickel may indicate possible involvement of this effect in the mechanisms of nickel carcinogenesis.

Chemical-specific alterations in ras, p53, and beta-catenin genes in hemangiosarcomas from B6C3F1 mice exposed to o-nitrotoluene or riddelliine for 2 years.

The most prominent neoplastic lesions in mice in the 2-year studies of o-nitrotoluene and riddelliine were hemangiosarcomas. Fifteen o-nitrotoluene-induced hemangiosarcomas of the skeletal muscle, subcutaneous tissue, and mesentery; 12 riddelliine-induced hemangiosarcomas of the liver; and 15 spontaneous subcutaneous hemangiosarcomas were examined for genetic alterations in ras, p53, and beta-catenin genes. Mutations in at least one of these genes were identified in 13 of 15 (87%) of the o-nitrotoluene-induced hemangiosarcomas with missense mutations in p53 exons 5-8 detected in 11 of 15 (73%) of these neoplasms. Seven of 15 (47%) hemangiosarcomas from mice exposed to o-nitrotoluene had deletions at exon 2 splice sites or smaller deletions in the beta-catenin gene. K-ras mutation was detected in only 1 of the 15 (7%) o-nitrotoluene-induced hemangiosarcomas. In contrast to the o-nitrotoluene study, 7/12 (58%) riddelliine-induced hemangiosarcomas had K-ras codon 12 GTT mutations and, when screened by immunohistochemistry, 9/12 (75%) had strong staining for the p53 protein in malignant endothelial cells, the cells of origin of hemangiosarcomas. Riddelliine-induced hemangiosarcomas were negative for the beta-catenin protein. Spontaneous hemangiosarcomas from control mice lacked both p53 and beta-catenin protein expression and ras mutations. Our data indicated that p53 and beta-catenin mutations in the o-nitrotoluene-induced hemangiosarcomas and K-ras mutations and p53 protein expression in riddelliine-induced hemangiosarcomas most likely occurred as a result of the genotoxic effects of these chemicals. It also suggests that these mutations play a role in the pathogenesis of the respective hemangiosarcomas in B6C3F1(1) mice.

Reactive oxygen-induced carcinogenesis causes hypermethylation of p16(Ink4a) and activation of MAP kinase.

BACKGROUND: Implantation of foreign materials into mice and humans has been noted to result in the appearance of soft tissue sarcomas at the site of implantation. These materials include metal replacement joints and Dacron vascular grafts. In addition, occupational exposure to nickel has been shown to result in an increased risk of carcinogenesis. The molecular mechanisms of foreign body-induced carcinogenesis are not fully understood. MATERIALS AND METHODS: In order to gain insight into these mechanisms, we implanted nickel sulfide into wild type C57BL/6 mice as well as a mouse heterozygous for the tumor suppressor gene, p53. Malignant fibrous histiocytomas arose in all mice, and we have characterized the profile of tumor suppressor genes and signal transduction pathways altered in these cells. RESULTS: All tumors demonstrated hypermethylation of the tumor suppressor gene p16, as well as activation of the mitogen activated protein kinase (MAP kinase) signaling pathway. This knowledge may be beneficial in the prevention and treatment of tumors caused by foreign body implantation. CONCLUSIONS: Oxidative stress induced by nickel sulfide appears to cause loss of p16 and activation of MAP kinase signaling. These findings support the hypothesis of synergistic interactions between MAP kinase activation and p16 loss in carcinogenesis.

Potentiation of antitumor effects of cisplatin by tumor necrosis factor-beta.

Recombinant tumor necrosis factor-beta potentiated the inhibitory effect of cisplatin on intramuscularly transplanted GA-1 tumor and liver metastasis in mice. The antitumor effect was related to cytotoxic and cytostatic activities of the test preparations rather than to initiation of apoptosis.

Immunohistochemical evaluation of chemically induced rhabdomyosarcomas in rats: diagnostic utility of MyoD1.

Monoclonal antibodies (mAbs) to selected muscle proteins were assessed as potential immunohistochemical markers to assist in the definitive diagnosis of poorly differentiated soft tissue sarcomas in rats. A series of 7 rat rhabdomyosarcomas (RMS) induced with nickel subsulfide were studied by light microscopy and were evaluated for immunoreactivity to desmin, vimentin, fast (type II isoform) skeletal myosin, alpha-actin (smooth muscle isoform), or MyoD1 (myogenic regulatory protein) mAbs using an avidin-biotin-chromogen technique. Consecutive RMS slices were fixed in 10% neutral buffered formalin (the fixative routinely used in carcinogenicity bioassays) for periods of 3 days or 2 mo prior to paraffin embedding to determine the effect of fixation time on immunoreactivity. Desmin and vimentin mAbs bound to many cells of all tumors, but fixation for 2 mo resulted in irretrievable loss of desmin and vimentin binding. Fast myosin and alpha-actin mAbs bound to many cells in 1 RMS but to < 1% of the cells in the remainder. MyoD1 mAb bound to tumor cell nuclei in 5/7 RMS with no loss of staining in tissue fixed for 2 mo. Results indicate that MyoD1 immunostaining, in contrast to desmin, maintains its sensitivity following prolonged formalin fixation and may be of value to distinguish RMS from other soft tissue sarcomas in the rat.

In vitro exposure to cadmium in rat L6 myoblasts can result in both enhancement and suppression of malignant progression in vivo.

Cadmium (Cd), a carcinogenic metal in humans and rodents, has been shown to transform cells in vitro. Cd in certain instances can also be anti-carcinogenic. The effects of Cd have been studied in different mammalian cell culture systems, where it has been shown to increase expression of several proto-oncogenes. In the present study the ability of Cd to affect malignant transformation was systematically investigated in L6 cells. Cells were grown in monolayer culture with concentrations of either 0 or 0.5 microM CdCl2 in the medium. Cell cultures treated with Cd for 9 weeks showed growth of large colonies in soft agar, while untreated control cells did not. When injected s.c. into athymic nude mice the 9 week Cd-treated cells gave rise to large, highly malignant sarcomas, resulting in high host mortality (9 dead/9 injected, 100%) by 7 weeks. Mice injected with untreated control cells also developed tumors, but of significantly smaller size and growth rate and associated with a lower host mortality (4/10, 40%, P

Relative susceptibilities of C57BL/6, (C57BL/6 x C3H/He)F1, and C3H/He mice to acute toxicity and carcinogenicity of nickel subsulfide.

The aim of this study was to compare susceptibility of mice of different strains to the toxicity and carcinogenicity of nickel subsulfide (Ni3S2), a water insoluble compound suspected to damage cells through oxidative mechanisms. Groups of 30 male mice of each strain, C57BL/6 (C57BL), (C57BL x C3H/He)F1 (B6C3F1), and C3H/He (C3H), were injected with single doses of 0.5-10 mg of Ni3S2/site into the thigh muscle and observed for up to 78 weeks. The highest Ni3S2 dose was lethal within 1 week to C57BL (93%) > B6C3F1 (80%) > C3H (53%) mice. The most susceptible C57BL mice also had the most severe necrotic/inflammatory kidney damage, compared with that in the other mice. The final incidence of local sarcomas at the 5 mg Ni3S2 dose was: C3H (97%) > B6C3F1 (76%) > C57BL (40% of mice at risk, i.e. those surviving at least 25 week; P < 0.05 or better as compared to the incidence in C3H mice). The relatively highest acute toxicity of Ni3S2 in C57BL mice observed in the present study, concurred with the weakest antioxidant response to systemic water-soluble nickel(II), resulting in reduction in glutathione (GSH) level and increased lipid peroxidation (LPO) in their kidneys and livers, two main targets of acute nickel toxicity, reported by us previously (Toxicol. Lett. 1991, 57, 269; ibid. 1991, 58, 121). Ni3S2 deposited in the muscle, therefore, constitutes a source of soluble nickel that can reach and damage distant organs. THe strongest tumor response in C3H mice relative to other strains did, in turn, concur with the lowest base levels of GSH and highest LPO in their muscle, the target for Ni3S2 carcinogenesis. Thus, the acute toxicity and carcinogenicity of Ni3S2 and Ni3S2-derived soluble nickel(II) in mice seem to depend, at least in part, on antioxidant capacity of target organs, which varies among different strains.