The Fate of Chrysotile-Induced Multipolar Mitosis and Aneuploid Population in Cultured Lung Cancer Cells

Abstract

Chrysotile is one of the six types of asbestos, and it is the only one that can still be commercialized in many countries. Exposure to other types of asbestos has been associated with serious diseases, such as lung carcinomas and pleural mesotheliomas. The association of chrysotile exposure with disease is controversial. However, in vitro studies show the mutagenic potential of chrysotile, which can induce DNA and cell damage. The present work aimed to analyze alterations in lung small cell carcinoma cultures after 48 h of chrysotile exposure, followed by 2, 4 and 8 days of recovery in fiber-free culture medium. Some alterations, such as aneuploid cell formation, increased number of cells in G2/M phase and cells in multipolar mitosis were observed even after 8 days of recovery. The presence of chrysotile fibers in the cell cultures was detected and cell morphology was observed by laser scanning confocal microscopy. After 4 and 8 days of recovery, only a few chrysotile fragments were present in some cells, and the cellular morphology was similar to that of control cells. Cells transfected with the GFP-tagged α-tubulin plasmid were treated with chrysotile for 24 or 48 h and cells in multipolar mitosis were observed by time-lapse microscopy. Fates of these cells were established: retention in metaphase, cell death, progression through M phase generating more than two daughter cells or cell fusion during telophase or cytokinesis. Some of them were related to the formation of aneuploid cells and cells with abnormal number of centrosomes.

Single-walled carbon nanotube-induced mitotic disruption

“…The coefficient of variance (CV) of G1 and G2/M was higher in SWCNT-treated cells than that in PBS treated cells further indicating disruption of the cell cycle in SWCNT-treated cells. The disruption of the cell cycle observed 24 h following SWCNT exposure was comparable to the level observed with the potent carcinogenic fiber asbestos [48]. The dose of carbon nanotubes was three-fold lower than the effective dose of asbestos.…”

“…The ability of asbestos fibers to induce aneuploidy in vitro is highly correlated with the ability to induce mesotheliomas in vivo; this provides data supporting the importance of aneuploidy in carcinogenesis due to particulates with high aspect ratios [81]. Chrysotile has also been observed to cause a G2/M block similar to the block observed with SWCNT [48]. The dose of chrysotile used in the in vitro studies was three-fold higher than the lowest dose of SWCNT that induced similar damage.…”

Cytogenetic evaluation of functionalized single-walled carbon nanotube in mice bone marrow cells

“…Although it is most likely that this impairment in cell cycle progression is associated with f‐SWCNT, further experiments are needed to elucidate the biochemical mechanisms involved. Several reports (Cortez et al, , ; Sargent et al, ; Siegrist et al, ) are in accordance with our study, showing that interaction between carbon nanotubes and DNA produces a conformational change at G–C rich areas on chromosomal and telomeric DNA. DNA intercalation and telomeric binding have been shown to induce damage to chromsomes, the carbon nanotubes at and above certain doses may possibly cause damage.…”

Independent of ErbB1 gene copy number, EGF stimulates migration but is not associated with cell proliferation in non-small cell lung cancer

“…The possibility of a fragile site near the ErbB1 gene has also been suggested to contribute to breaks near the ErbB1 gene region [30]. The HK2 cells are comprised of 2.4% cells undergoing multipolar mitosis and 3.7% micronucleated cells, suggesting that errors in chromosome segregation may occur during mitosis in these cells [31]. Thus, subpopulations of cells with different ErbB1 gene copy numbers were observed in culture.…”