Panax notoginseng saponin reduces IL-1β-stimulated apoptosis and endoplasmic reticulum stress of nucleus pulposus cells by suppressing miR-222-3p

BACKGROUND: It is well documented that the malignant biological behaviors of nucleus pulposus cells (NPCs) could trigger intervertebral disc degeneration (IDD). Panax notoginseng saponin (PNS) is a traditional Chinese medicine that inhibits osteoclastogenesis. However, its effects on the phenotypes of NPCs in IDD remains largely unknown. This study sought to examine the role of PNS in IDD and its regulatory mechanism. METHODS: First, human NPCs (hNPCs) were treated with interleukin-1 beta (IL-1β) to induce an IDD cell model. Cell proliferation and apoptosis were estimated by Cell Counting Kit-8 (CCK-8) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays. Western blot was employed to examine the levels of proteins related to apoptosis and endoplasmic reticulum (ER) stress. Enzyme-linked immunosorbent assays (ELISAs) were used to test inflammatory factors levels. Immunofluorescence (IF) assays were used to determine the nuclear translocation of nuclear factor-kappa beta (NF-κB) p65. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect miR-222-3p expression. RESULTS: We discovered that PNS enhanced the viability but reduced the apoptosis, inflammation, and ER stress response of IL-1β-induced hNPCs in a concentration-dependent manner. Additionally, PNS significantly reduced miR-222-3p expression in the IL-1β-induced hNPCs. Notably, these PNS effects were reversed by the upregulation of miR-222-3p. CONCLUSIONS: In summary, PNS appears to facilitate the proliferation and attenuate the apoptosis, inflammatory response, and ER stress response of IL-1β-induced hNPCs by inhibiting miR-222-3p expression. Our findings provide a theoretical basis for a novel drug application in IDD research.