Man-made mineral fibers (MMMFs) are substitutes for asbestos. MMMFs are widely used as insulation, but their molecular mechanisms underlying the tumorigenic effects in vivo have been poorly studied. For this reason, this work aimed to explore the properties and carcinogenic molecular mechanisms of MMMFs. The three MMMFs, rock wool (RW), glass fibers (GFs), and ceramic fibers (CFs), were prepared into respirable dust. Particle size, morphology, and chemical composition were analyzed by laser particle analyzer, scanning electron microscope, and X-ray fluorescence spectrometer, respectively. The Wistar rats were administered multiple intratracheal instillations of three MMMFs once a month. Then, several parameters (e.g. body mass, lung mass, and lung histology) were measured at 1, 3, and 6 months. After that, levels of P53, P16, C-JUN, and C-FOS mRNA and protein were measured by quantitative real-time reverse transcription polymerase chain reaction and Western blotting. This work found that exposure to MMMFs could influence the growth of body mass and increase lung mass. General conditions showed white nodules and irregular atrophy. In addition, MMMFs could lead to inactivation of anti-oncogene P16 and activation of proto-oncogenes (C-JUN and C-FOS) in the mRNA and protein levels, in which GF and CF were more obvious compared with RW. The effect of MMMFs was different, which may be related to the physical and chemical characteristics of different MMMFs. In conclusion, MMMFs (GF and CF) could induce an unbalanced expression of cancer-related genes in the lung tissues of rats. The understanding of the determinants of toxicity and carcinogenicity provides a scientific basis for developing and introducing new safer MMMF products, and the present study provides some useful insights into the carcinogenic mechanism of MMMFs.
Keywords: C-FOS; C-JUN; MMMFs; P16; P53; carcinogenicity.