Stress response in periodontal ligament stem cells may contribute to bisphosphonate-associated osteonecrosis of the jaw: A gene expression array analysis

Gene expression alterations in periodontal ligament stem cells (PDLSCs) during bisphosphonate (BP) usage and the transcriptomic mechanism underlying BP-related osteonecrosis of the jaw have not been fully elucidated. In the present study, human PDLSCs were isolated from adults with no history of periodontal disease, and subsequently incubated and treated with zoledronate on days 3 and 5. Subsequently, PDLSCs from all timepoints were screened using an Affymetrix Gene Expression Array. Limma differential expression analysis was performed on a normalized gene expression matrix, followed by cluster analysis, pathway and network analyses. Overall, 906 genes (352 upregulated and 554 downregulated) exhibited differential expression levels between days 0 and 5, and these were termed slow-response genes. These slow-response genes were enriched in cellular stress response signaling pathways (upregulated genes), as well as proliferation- and ossification-associated signaling pathways (downregulated genes). Furthermore, 168 (day 3 vs. 0) and 105 (day 5 vs. 3) genes were differentially expressed between adjacent timepoints. These genes were also enriched in stress response- and proliferation-associated signaling pathways, but not in ossification-associated signaling pathways. Poly(ADP-ribose) polymerase 1 (PARP1) and CYLD lysine 63 deubiquitinase (CYLD) had the most protein-protein interaction partners among the slow-response genes and were connected with both stress- (e.g. caspase-1) and ossification-associated genes [e.g. secreted phosphoprotein 1 and collagen type I α1 chain (COL1A1)]. BP treatment induced stress response-like transcriptional alterations in PDLSCs, followed by inhibition of proliferation and ossification. These alterations may contribute to the onset of jaw osteonecrosis. PARP1 and CYLD may be two key genes involved in this pathological procedure.