Published online Jun 26, 2020. doi: 10.4252/wjsc.v12.i6.500
Peer-review started: December 18, 2019
First decision: February 20, 2020
Revised: March 17, 2020
Accepted: April 8, 2020
Article in press: April 8, 2020
Published online: June 26, 2020
Processing time: 190 Days and 3.4 Hours
With continuous advancement of industrial society, environmental pollution has become more and more serious. There has been an increase in infertility caused by environmental factors. Nonylphenol (NP) is a stable degradation product widely used in daily life and production and has been proven to affect male fertility. However, the underlying mechanisms therein are unclear. Thus, it is necessary to study the effect and mechanism of NP on spermatogonial stem cells (SSCs).
To investigate the cytotoxic effect of NP on SSCs via the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway.
SSCs were treated with NP at 0, 10, 20 or 30 µmol. MTT assay was performed to evaluate the effect of NP on the proliferation of SSCs. Flow cytometry was conducted to measure SSC apoptosis. The expression of Bad, Bcl-2, cytochrome-c, pro-Caspase 9, SOX-2, OCT-4, Nanog, Nanos3, Stra8, Scp3, GFRα1, CD90, VASA, Nanos2, KIT, PLZF and PI3K/AKT/mTOR-related proteins was observed by western blot, and the mRNA expression of SOX-2, OCT-4 and Nanog was detected by quantitative reverse transcription polymerase chain reaction.
Compared with untreated cells (0 μmol NP), SSCs treated with NP at all concentrations showed a decrease in cell proliferation and expression of Bcl-2, Nanog, OCT-4, SOX-2, Nanos3, Stra8, Scp3, GFRα1, CD90, VASA, Nanos2, KIT, and PLZF (P < 0.05), whereas the expression of Bad, cytochrome-c, and pro-Caspase 9 increased significantly (P < 0.05). We further examined the PI3K/AKT/mTOR pathway and found that the phosphorylation of PI3K, AKT, mTORC1, and S6K was significantly decreased by NP at all concentrations compared to that in untreated SSCs (P < 0.05). NP exerted the greatest effect at 30 μmol among all NP concentrations.
NP attenuated the proliferation, differentiation and stemness maintenance of SSCs while promoting apoptosis and oxidative stress. The associated mechanism may be related to the PI3K/AKT/mTOR pathway.
Core tip: With continuous advancement of industrial society, environmental pollution has become more and more serious. There has been an increase in infertility caused by environmental factors. Nonylphenol is a stable degradation product widely used in daily life and production and has been proven to affect male fertility. Our study demonstrated that nonylphenol reduced the proliferation, differentiation and stemness maintenance of spermatogonial stem cells while promoting apoptosis and oxidative stress. The mechanism may be related to the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathway, providing a potential method for the treatment of male infertility.