Oral squamous cell carcinoma (OSCC) is the most common primary oral cancer, characterized by a very poor prognosis and a median overall survival of 37.6 months (Zanoni et al., 2019). Contemporary standard treatment is comprised of surgical resection with immediate reconstruction, followed by adjuvant radiotherapy with or without concurrent systemic therapy depending on final surgical pathologic analysis (Caudell et al., 2022). OSCC is susceptible to local recurrence and regional and distant metastasis, resulting in a 5-year survival rate of only 50–60 % (Bray et al., 2024, Li et al., 2023). Treatment failure reflects OSCC complexity due to a complicated immunomicroenvironment landscape, high intra- and inter-tumor heterogeneity, and radioresistance or/and chemoresistance influenced by oral cancer stemness (Li et al., 2024a, Zhi et al., 2024).

Porphyromonas gingivalis (P. g) is the most important pathogenic bacteria for periodontal disease. Although causality is yet to be definitively established, emerging trends implicate periodontal pathogens such as P. g as associated with the cancerous state (Lamont et al., 2022). P. g has been recognized as an independent microorganism that plays a role in tumor progression and may increase mortality risk in patients suffering from OSCC (Li et al., 2024c). In addition, infection with P. g correlates with a poor prognosis in OSCC patients (Li et al., 2024b), and P. g is oncopathogenic in animal models (Wen et al., 2020). Fundamental pathophysiological processes, for example tissue homeostasis, chronic inflammation, and malignant tumor, are modulated by purinergic pathways. The nucleoside adenosine and nucleotides including adenine mononucleotides like ADP and ATP are key mediators in purinergic signaling (Di Virgilio, 2012). Intriguingly, a P. g homologue of nucleoside diphosphate kinase (NDK), an ATP-consuming enzyme, is secreted extracellularly and is associated with the fate of gingival epithelial cells (Johnson et al., 2015, Yilmaz et al., 2008). Moreover, the effects of extracellular ATP in the tumor microenvironment (TME) depend on the repertoire of P2 receptors (P2X) and ATP-degrading enzymes (ectonucleotidases like NDK) expressed by immune/tumor/stromal cells (Di Virgilio et al., 2018, Kepp et al., 2021, Pellegatti et al., 2008, Wei et al., 2024). Previous studies have also shown that extracellular ATP concentration and the activation of purinergic ligand-gated ion channel 7 (P2X7) are closely related to cell fate in digestive system cancers (Wang et al., 2024). Although P2X7 is upregulated in breast cancer, cervical cancer, gastric cancer, and so on (Wei et al., 2024, Zanoni et al., 2022), and is activated in cell proliferation, invasion, and migration, the role of P2X7 in OSCC is still unclear and requires further research.

Herein, we hypothesized that NDK, one of P. g virulence factors, might exhaust extracellular ATP in TME to give rise to OSCC development via P2X7 modulation. In this research, we investigated the expression and function of P2X7 in patient-derived OSCC. Additionally, an in vitro co-culture model containing human OSCC cell lines (SCC 9 and SCC 25) and P. g W83 (high-invasive, FimA IV-deficient mutant strain) or its NDK knockout variant (P. g-△NDK) was constructed respectively that mimics OSCC TME. We subsequently carried out various key experiments, including CCK-8, wound healing, transwell, LDH release, ATP detection assays, western blotting, flow cytometry, and Fluo-4 Ca2 + detection, to evaluate proliferation, migration, invasion, and cytotoxicity, as well as the relationship between ATP and P2X7.