Due to its potential adverse effects on human health, perfluorooctanoic acid (PFOA), one of the once widely used legacy per- and polyfluoroalkyl substances (PFASs), has been recently replaced by its novel alternatives including hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA). These alternative PFASs are detected in water and exposed workers. PFASs can enter organs like thyroids, however, it is yet unknown whether the new alternatives are safer than PFOA. In the current study, we compared the thyroid disrupting effects of PFOA and its alternatives GenX and ADONA in vitro with both rat thyroid cell line FRTL5 and primary normal human thyroid (NHT) cells. Cells were exposed to ascendant doses of PFOA, GenX or ADONA for various incubation time and cell viability was assessed by WST-1 assay and LDH assay. The proliferation rate of survived cells was determined by crystal violet-based cell proliferation assay and MTT assay. The gene expression of thyroid hormone regulation-related genes in thyroid cells after exposure was quantified by RT-PCR and Western blot. Our data showed that both PFOA and GenX reduced thyroid cell viability in both dose and time dependent manner, with GenX being more toxic than PFOA at the same condition. Similarly, the proliferation rate of cells survived exposure to PFOA and GenX was considerably impaired, with GenX showing more profound adverse effect than PFOA. Unlike PFOA and GenX, ADONA showed no apparent adverse effects on the viability and proliferation of both thyroid cell types. Gene expression data revealed that all three PFASs altered gene expression in both thyroid cells and the altered gene expression seemed to be PFAS and cell type dependent. Taken together, our data reveal that the thyroid disrupting effects is increased in the order of GenX > PFOA > ADONA. Our findings will be beneficial for the guidance of the future usage of PFASs and development of better alternatives.

由于其对人类健康的潜在不利影响，全氟辛酸 (PFOA) 是曾经广泛使用的传统全氟和多氟烷基物质 (PFAS) 之一，最近已被其新型替代品所取代，包括六氟环氧丙烷二聚酸 (GenX ) 和 4,8-二氧杂-3H-全氟壬酸铵 (ADONA)。这些替代的全氟和多氟烷基物质在水和暴露的工人中被检测到。PFAS 可以进入甲状腺等器官，但是，尚不清楚新替代品是否比 PFOA 更安全。在目前的研究中，我们在体外比较了 PFOA 及其替代品 GenX 和 ADONA 对大鼠甲状腺细胞系 FRTL5 和原代正常人甲状腺 (NHT) 细胞的甲状腺破坏作用。将细胞暴露于递增剂量的 PFOA、GenX 或 ADONA 不同的孵育时间，并通过 WST-1 测定和 LDH 测定评估细胞活力。通过基于结晶紫的细胞增殖试验和MTT试验测定存活细胞的增殖率。通过RT-PCR和Western印迹定量暴露后甲状腺细胞中甲状腺激素调节相关基因的基因表达。我们的数据显示，PFOA 和 GenX 都以剂量和时间依赖性方式降低了甲状腺细胞的活力，在相同条件下，GenX 比 PFOA 毒性更大。同样，暴露于 PFOA 和 GenX 后存活的细胞增殖率显着受损，GenX 显示出比 PFOA 更严重的不利影响。与 PFOA 和 GenX 不同，ADONA 对两种甲状腺细胞类型的活力和增殖没有表现出明显的不利影响。基因表达数据显示，所有三种 PFAS 都改变了甲状腺细胞中的基因表达，并且改变的基因表达似乎与 PFAS 和细胞类型有关。综上所述，我们的数据表明，甲状腺干扰作用以 GenX > PFOA > ADONA 的顺序增加。我们的研究结果将有助于指导未来 PFAS 的使用和开发更好的替代品。