Intracellular nutrient metabolism, particularly the metabolism of essential amino acids (EAAs), is crucial for cellular functions, including energy production and redox homeostasis. An EAA deficiency can lead to cellular dysfunction and oxidative stress. This study explores the mechanisms underlying cellular responses to EAA starvation, focusing on ROS-induced DNA damage and apoptosis. MC3T3-E1 cells were subjected to EAA starvation, and various assays were conducted to assess cell proliferation, survival, DNA damage, and apoptosis. The antioxidant N-acetylcysteine (NAC) was employed to block ROS formation and mitigate cellular damage. Gene expression and Western blot analyses were performed to elucidate molecular pathways. EAA starvation-induced ROS generation, DNA damage, and apoptosis in MC3T3-E1 cells. NAC administration effectively reduced DNA damage and apoptosis, highlighting the pivotal role of ROS in mediating these cellular responses during EAA deficiency. This study demonstrates that EAA starvation triggers ROS-mediated DNA damage and apoptosis, offering insights into the intricate interplay between nutrient deficiency, oxidative stress, and programmed cell death. NAC emerges as a potential therapeutic intervention to counteract these adverse effects.

The high-glucose conditions caused by diabetes mellitus (DM) exert several effects on cells, including inflammation. miR-146a, a kind of miRNA, is involved in inflammation and may be regulated mutually with reactive oxygen species (ROS), which are produced under high-glucose conditions. In the present study, we used human periodontal ligament cells (hPDLCs) to determine the effects of the high-glucose conditions of miR-146a and their involvement in the regulation of oxidative stress and inflammatory cytokines using Western blotting, PCR, ELISA and other methods. When hPDLCs were subjected to high glucose (24 mM), cell proliferation was not affected; inflammatory cytokine expression, ROS induction, interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) expression increased, but miR-146a expression decreased. Inhibition of ROS induction with the antioxidant N-acetyl-L-cysteine restored miR-146a expression and decreased inflammatory cytokine expression compared to those under high-glucose conditions. In addition, overexpression of miR-146a significantly suppressed the expression of the inflammatory cytokines IRAK1 and TRAF6, regardless of the glucose condition. Our findings suggest that oxidative stress and miR-146a expression are mutually regulated in hPDLCs under high-glucose conditions.

Shikonin is a naturally occurring compound known for its anti-inflammatory properties and wound-healing effects. The increased production of reactive oxygen species (ROS) causes oxidative stress and influences the progression of periodontal disease. MiR-146a, a type of microRNA, is reported to be involved in the control of inflammation. This research seeks to examine the anti-inflammatory and antioxidant properties of shikonin on human gingival fibroblasts (hGFs) under inflammation induced by Interleukin (IL)-1β, which is associated with the progression of periodontitis and to further investigate the effect of shikonin on miR-146a expression. Cell proliferation, scratching, and toxicity tests were performed, and the shikonin concentration was set at 0.1 µM. The levels of ROS, miR-146a, and inflammatory cytokines were measured to examine the effects of shikonin on inflammation. The addition of shikonin reduced IL-6 by approximately 20% and reduced IL-8 by approximately 30% compared to IL-6 and IL-8 production and expression induced by IL-1β. MiR-146a expression increased 3.38-fold under IL-1β-induced inflammation but showed a decreasing trend with the addition of shikonin. These results suggest that IL-1β-induced inflammation and oxidative stress are regulated by shikonin in hGFs and are associated with the expression of miR-146a.