Less is more: biological effects of NiSe2/rGO nanocomposites with low dose provide new insight for risk assessment

Low-dose graphene oxide promotes tumor cells proliferation by activating PI3K-AKT-mTOR signaling via cellular membrane protein integrin αV

Along with the increasing production and application of graphene oxide (GO), its environmental health and safety (EHS) risks have become a global concern. Numerous studies have investigated the biosafety and toxicity mechanisms associated with GO, however, the majority of previous studies were based on its direct toxic dose, which could not reflect the realistic state of environmental exposure of GO with an indirect toxic dose (low dose). Meanwhile, the effects of low-dose GO on the progression of tumors are still unclearly. Herein, we found that GO can promote multiple types of tumor cell proliferation under its low-dose treatment. Moreover, the lateral size of GO has no obvious distinction on its promoting effect on tumor proliferation. The mechanistic investigation revealed that low-dose GO treatment increased the expression level of integrin αV protein, a cell membrane receptor, and further lead to the constitutively activated PI3K/AKT/mTOR signaling pathway and promoted mitotic progression. Collectively, these findings increased our understanding of the detrimental effects of GO in promoting tumor proliferation, as well as improved our biosafety assessment at its realistic exposure doses.

Exposure to Polypropylene Microplastics via Oral Ingestion Induces Colonic Apoptosis and Intestinal Barrier Damage through Oxidative Stress and Inflammation in Mice

Extensive environmental pollution by microplastics has increased the risk of human exposure to plastics. However, the biosafety of polypropylene microplastics (PP-MPs), especially of PP particles < 10 μm, in mammals has not been studied. Thus, here, we explored the mechanism of action and effect of exposure to small and large PP-MPs, via oral ingestion, on the mouse intestinal tract. Male C57BL/6 mice were administered PP suspensions (8 and 70 μm; 0.1, 1.0, and 10 mg/mL) for 28 days. PP-MP treatment resulted in inflammatory pathological damage, ultrastructural changes in intestinal epithelial cells, imbalance of the redox system, and inflammatory reactions in the colon. Additionally, we observed damage to the tight junctions of the colon and decreased intestinal mucus secretion and ion transporter expression. Further, the apoptotic rate of colonic cells significantly increased after PP-MP treatment. The expression of pro-inflammatory and pro-apoptosis proteins significantly increased in colon tissue, while the expression of anti-inflammatory and anti-apoptosis proteins significantly decreased. In summary, this study demonstrates that PP-MPs induce colonic apoptosis and intestinal barrier damage through oxidative stress and activation of the TLR4/NF-κB inflammatory signal pathway in mice, which provides new insights into the toxicity of MPs in mammals.