title: Investigating palygorskite's role in the development of mesothelioma in southern Nevada: Insights into fiber-induced carcinogenicity.
abstract: Similar to asbestos fibers, nonregulated mineral fibers can cause malignant mesothelioma (MM). Recently, increased proportions of women and young individuals with MM were identified in southern Nevada, suggesting that environmental exposure to carcinogenic fibers was causing the development of MM. Palygorskite, a fibrous silicate mineral with a history of possible carcinogenicity, is abundant in southern Nevada. In this study, our aim was to determine whether palygorskite was contributing to the development of MM in southern Nevada. While palygorskite, in vitro, displayed some cytotoxicity toward primary human mesothelial (HM) cells and reduced their viability, the effects were roughly half of those observed when using similar amounts of crocidolite asbestos. No Balb/c (0/19) or MexTAg (0/18) mice injected with palygorskite developed MM, while 3/16 Balb/c and 13/14 MexTAg mice injected with crocidolite did. Lack of MM development was associated with a decreased acute inflammatory response, as injection of palygorskite resulted in lower percentages of macrophages (p = .006) and neutrophils (p = .02) in the peritoneal cavity 3 d after exposure compared to injection of crocidolite. Additionally, compared to mice injected with crocidolite, palygorskite-injected mice had lower percentages of M2 (tumor-promoting) macrophages (p = .008) in their peritoneal cavities when exposed to fiber for several weeks. Our study indicates that palygorskite found in the environment in southern Nevada does not cause MM in mice, seemingly because palygorskite, in vivo, fails to elicit inflammation that is associated with MM development. Therefore, palygorskite is not a likely contributor to the MM cases observed in southern Nevada.
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: David
authors.initials: D
authors.lastname: Larson
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Powers
authors.affiliation: b CNRS, IRD, CEREGE UM34 , Aix-Marseille Université , Aix en Provence, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Ambrosi
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Mika
authors.initials: M
authors.lastname: Tanji
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.|c Department of Molecular Biosciences and Bioengineering , University of Hawai'i at Manoa , Honolulu , Hawai'i , USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Napolitano
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Erin G
authors.initials: EG
authors.lastname: Flores
authors.affiliation: d ERIM , Université de la Nouvelle-Calédonie , Nouméa , New Caledonia.
authors.forename: Francine
authors.initials: F
authors.lastname: Baumann
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Pellegrini
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Cormac J
authors.initials: CJ
authors.lastname: Jennings
authors.affiliation: e Department of Geoscience , University of Nevada Las Vegas , Las Vegas , Nevada , USA.
authors.forename: Brenda J
authors.initials: BJ
authors.lastname: Buck
authors.affiliation: f Department of Environmental, Geographical and Geological Sciences , Bloomsburg University of Pennsylvania , Bloomsburg , Pennsylvania , USA.
authors.forename: Brett T
authors.initials: BT
authors.lastname: McLaurin
authors.affiliation: g U.S. Department of Agriculture , Natural Resources Conservation Service , Las Vegas , Nevada , USA.
authors.forename: Doug
authors.initials: D
authors.lastname: Merkler
authors.affiliation: h National Centre for Asbestos Related Diseases, School of Medicine and Pharmacology , University of Western Australia, Harry Perkins Institute for Medical Research , Nedlands, Perth , Western Australia.
authors.forename: Cleo
authors.initials: C
authors.lastname: Robinson
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.|i Department of Thoracic Surgery , Queen's Medical Center , Honolulu , Hawai'i , USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Morris
authors.affiliation: j Geological Engineering Department , Hacettepe University , Beytepe , Ankara , Turkey.
authors.forename: Meral
authors.initials: M
authors.lastname: Dogan
authors.affiliation: k Chemical and Biochemical Engineering Department & Center for Global and Regional Environmental Research , University of Iowa , Iowa City , Iowa , USA.
authors.forename: A Umran
authors.initials: AU
authors.lastname: Dogan
authors.affiliation: l Department of Cardiothoracic Surgery , New York Langone Medical Center , New York , New York , USA.
authors.forename: Harvey I
authors.initials: HI
authors.lastname: Pass
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Sandra
authors.initials: S
authors.lastname: Pastorino
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Carbone
authors.affiliation: a University of Hawai'i Cancer Center , University of Hawai'i , Honolulu , Hawai'i , USA.
authors.forename: Haining
authors.initials: H
authors.lastname: Yang
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects*; D008175:Lung Neoplasms / Q000139:chemically induced / Q000473:pathology*; D017616:Magnesium Compounds / Q000633:toxicity*; D008654:Mesothelioma / Q000139:chemically induced / Q000473:pathology*; D000086002:Mesothelioma, Malignant; D051379:Mice; D008807:Mice, Inbred BALB C; D009505:Nevada; D017655:Silicon Compounds / Q000633:toxicity*
chemical_list: D017616:Magnesium Compounds; D017655:Silicon Compounds; C026325:attapulgite