RESUMO
Per- and polyfluorinated substances (PFAS) have been associated with numerous human diseases. Recent in vitro studies have implicated the association of PFAS with an increased risk of breast cancer in humans. This study aimed to assess the toxic effects of PFAS during the development of human breast cancer using a zebrafish xenograft model. Perfluorooctanoic acid (PFOA) was used as a PFAS chemical of interest for this study. Two common breast cancer cell lines, MCF-7 and MDA-MB-231, were used to represent the diversity of breast cancer phenotypes. Human preadipocytes were co-implanted with the breast cancer cells into the zebrafish embryos to optimize the microenvironment for tumor cells in vivo. With this modified model, we evaluated the potential effects of the PFOA on the metastatic potential of the two types of breast cancer cells. The presence of human preadipocytes resulted in an enhancement to the metastasis progress of the two types of cells, including the promotion of cell in vivo migration and proliferation, and the increased expression levels of metastatic biomarkers. The enhancement of MCF-7 proliferation by preadipocytes was observed after 2 days post injection (dpi) while the increase of MDA-MB-231 proliferation was seen after 6 dpi. The breast cancer metastatic biomarkers, cadherin 1 (cdh1), and small breast epithelial mucin (sbem) genes demonstrated significant down- and upregulations respectively, by the co-injection of preadipocytes. In the optimized xenograft model, the PFOA consistently promoted cell proliferation and migration and altered the metastatic biomarker expression in MCF-7, which suggested a metastatic effect of PFOA on MCF-7. However, those effects were not consistently observed in MDA-MB-231. The presence of the preadipocytes in the xenograft model may provide a necessary microenvironment for the progress of tumor cells in zebrafish embryos. The finding suggested that the impacts of PFOA exposure on different phenotypes of breast cancers may differ.
RESUMO
Anthracene, a polycyclic aromatic hydrocarbon (PAH), is a widespread environmental pollutant that poses potential risks to human health. Exposure to anthracene can result in various adverse health effects, including skin-related disorders. Photo exposure sufficiently removes the anthracene from the environment but also generates more degradation products which can be more toxic. The goal of this study was to assess the change in anthracene dermotoxicity caused by photodegradation and understand the mechanism of this change. In the present study, over 99.99% of anthracene was degraded within 24 h of sunlight exposure, while producing many intermediate products including 9,10-anthraquinone and phthalic acid. The anthracene products with different durations of photo exposure were applied to 2D and 3D human keratinocyte cultures. Although the non-degraded anthracene significantly delayed the cell migration, the cell viability and differentiation decreased dramatically in the presence of the photodegraded anthracene. Anthracene photodegradation products also altered the expression patterns of a number of inflammation-related genes in comparison to the control cells. Among these genes, il1a, il1b, il8, cxcl2, s100a9, and mmp1 were upregulated whereas the tlr4 and mmp3 were downregulated by the photodegraded anthracene. Topical deliveries of the photodegraded and non-degraded anthracene to the dorsal skin of hairless mice showed more toxic effects by the photodegraded anthracene. The 4-hour photodegradation products of anthracene thickened the epidermal layer, increased the dermal cellularity, and induced the upregulation of inflammatory markers, il1a, il1b, s100a9, and mmp1. In addition, it also prevented the production of a gap junction protein, Connexin-43. All the evidence suggested that photodegradation enhanced the toxicities of anthracene to the skin. The 4-hour photodegradation products of anthracene led to clinical signs similar to acute inflammatory skin diseases, such as atopic and contact dermatitis, eczema, and psoriasis. Therefore, the potential risk of skin irritation by anthracene should be also considered when an individual is exposed to PAHs, especially in environments with strong sunlight.