Iron oxide nanoparticles (IONPs)-based contrast agents are widely used for T2-weighted magnetic resonance imaging (MRI) in clinical diagnosis, highlighting the necessity and importance to evaluate their potential systematic toxicities. Although a few previous studies have documented the toxicity concerns of IONPs to major organs, limited data are available on the potential reproductive toxicity caused by IONPs, especially when administrated via intravenous injection to mimic clinical use of MRI contrast agents. Our study aimed to determine whether exposure to IONPs would affect male reproductive system and cause other related health concerns in ICR mice. The mice were intravenously injected with different concentrations IONPs once followed by routine toxicity tests of major organs and a series of reproductive function-related analyses at different timepoints. As a result, most of the contrast agents were captured by reticuloendothelial system (RES) organs such as liver and spleen, while IONPs have not presented adverse effects on the normal function of these major organs. In contrast, although IONPs were not able to enter testis through the blood testicular barrier (BTB), and they have not obviously impaired the overall testicular function or altered the serum sex hormones levels, IONPs exposure could damage Sertoli cells in BTB especially at a relative high concentration. Moreover, IONPs administration led to a short-term reduction in the quantity and quality of sperms in a dose-dependent manner, which might be attributed to the increase of oxidative stress and apoptotic activity in epididymis. However, the semen parameters have gradually returned to the normal range within 14 days after the initial injection of IONPs. Collectively, these results demonstrated that IONPs could cause reversible damage to the reproductive system of male mice without affecting the main organs, providing new guidance for the clinical application of IONPs as T2-MRI contrast agents. Graphical Abstract

Background A growing number of studies indicate that circular RNAs (circRNAs) play critical roles in human diseases, and show great potential as biomarkers and therapeutic targets. This study aimed to investigate the expression and function of circANKS1B in prostate cancer (PC). Methods The expression of circANKS1B and miR‐152‐3p was analyzed by real‐time quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR). Cell migration and invasion were measured using a transwell assay. The interaction between circANKS1B and miR‐152‐3p was confirmed by a dual‐luciferase reporter gene assay. Rescue experiments were conducted to determine whether circANKS1B regulated the invasion of PC cells via the circANKS1B‐miR‐152‐3p‐TGF‐α pathway. Results The expression of circANKS1B was markedly upregulated in both PC cells and tissues. Moreover, high circANKS1B expression was associated with poor prognosis in PC patients. Dual‐luciferase reporter assay indicated that circANKS1B directly bound to miR‐152‐3p. Furthermore, circANKS1B negatively regulated miR‐152‐3p expression. Knockdown of circANKS1B markedly suppressed cell migration and invasion and TGF‐α expression in PC cells, whereas the effects of circANKS1B silencing were reversed by miR‐152‐3p deficiency. In addition, the impact of miR‐152‐3p silencing on invasion of circANKS1B‐deficient PC cells was also abrogated by TGF‐α deficiency. Overall, circANKS1B acts as a sponge for miR‐152‐3p to promote PC progression by upregulating TGF‐α expression. Conclusion Our findings reveal that circANKS1B may be a potential prognostic biomarker and therapeutic target for PC.

NADPH oxidase 4 (Nox4) is an important source of reactive oxygen species (ROS) production, and its expression is increased in lipopolysaccharide- (LPS-) stimulated lung epithelial cells. Polymerase δ-interacting protein 2 (Poldip2) has been proved to bind Nox4 and participates in oxidative stress and inflammation. However, the role of Poldip2/Nox4 in LPS-induced oxidative stress and inflammation in lung epithelial cells remains unclear. Cell viability was measured via MTT assays. The expression of Poldip2, Nox4, heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX-2), AKT, and p-AKT was detected by Western blotting and/or immunofluorescence. Poldip2 and Nox4 interaction was analyzed via coimmunoprecipitation (Co-IP) assay. NADPH enzymatic activity and production of ROS, prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were assessed simultaneously. The small interfering RNA (siRNA) or plasmid targeting Nox4 was used to downregulate or upregulate Nox4, and the lentiviral vector encoding Poldip2 was used to downregulate or upregulate Poldip2. The present study demonstrated that LPS stimulation significantly increased the protein levels of Poldip2 and Nox4 and proved that Poldip2 interacted with Nox4 proved by Co-IP. Importantly, Poldip2 acted as an upstream regulator of Nox4. The increased expression of Nox4 and COX-2; NADPH enzymatic activity; production of ROS, PGE2, TNF-α, and IL-1β; and decreased HO-1 expression were significantly suppressed by lentiviral Poldip2 shRNA downregulation but were increased by lentiviral upregulation of Poldip2. Furthermore, inhibiting of PI3K-AKT signaling notably attenuated LPS-induced Poldip2/Nox4 activation. Our study demonstrated that Poldip2 mediates LPS-induced oxidative stress and inflammation via interaction with Nox4 and was regulated by the PI3K-AKT signaling. Targeting Poldip2 could be a beneficial therapeutic strategy for the treatment of ALI.