Periodontal disease (PD) is strongly linked to increased risk of oral squamous cell carcinoma (OSCC); however, the specific mechanism through which the development of PD and OSCC is simultaneously promoted remains unclear. This study explored the impact of periodontal pathogens on OSCC progression and the contribution of periodontal pathogen-stimulated OSCC to PD development. The expression of osteoclastogenesis-inducing factors was assessed using quantitative reverse transcription polymerase chain reaction analysis following stimulation of OSCC with lipopolysaccharide (LPS) derived from the periodontal pathogen Porphyromonas gingivalis (Pg), a pathogen commonly responsible for PD. The cell counting kit-8 assay was used to determine the effects of Pg-LPS on OSCC proliferation and drug resistance to cisplatin and 5-fluorouracil. The effects of conditioned medium (CM) derived from Pg-LPS–stimulated OSCC on osteoclastogenesis was evaluated using tartrate-resistant acid phosphatase (TRAP) staining on bone marrow-derived macrophages (BMMs). Pg-LPS administration in SCC-25 and YD-8 OSCC cell lines induced a significant increase in receptor activator of nuclear factor kappa-B ligand mRNA expression; however, it did not affect cell proliferation. Treatment with CM derived from Pg-LPS–stimulated SCC-25 or YD-8 cells markedly enhanced the formation of TRAP-positive multinucleated cells during osteoclast differentiation of BMMs. Altogether, these findings demonstrate that Pg-LPS–stimulated OSCC promoted osteoclastogenesis through a paracrine mechanism.

Introduction
Materials and Methods
    1. Cell culture
    2. Conditioned media
    3. Bone marrow-derived macrophages isolation andosteoclast differentiation
    4. RNA extraction and quantitative reversetranscription polymerase chain reaction
    5. Tartrate-resistant acid phosphatase staining
    6. Cell proliferation assay
    7. Statistical analysis
Results
    1. Pg-LPS가 OSCC의 RANKL 발현에 미치는 영향
    2. Pg-LPS가 SCC-25, YD-8 cells의 M-CSF, OPG, IL-6발현에 미치는 효과
    3. Pg-LPS가 SCC-25, YD-8 cells의 cisplatin, 5-FU항암제 민감성에 미치는 효과
    4. Pg-LPS에 의해 자극되어진 SCC-25, YD-8 cells이 파골세포 분화에 미치는 효과
Discussion
Funding
Conflicts of Interest
References

• Bo Ram Keum(Department of Oral Physiology, School of Dentistry, Pusan National University, Yangsan 50612, Republic of Korea)
• Soon Chul Heo(Department of Oral Physiology, School of Dentistry, Pusan National University, Yangsan 50612, Republic of Korea)
• Hyung Joon Kim(Department of Oral Physiology, School of Dentistry, Pusan National University, Yangsan 50612, Republic of Korea) Corresponding author