Distinct Bone Resorption Patterns in Syngeneic Mouse Models of Gingival Squamous Cell Carcinoma Reflecting SCCVII Cell Line Heterogeneity

Aim Syngeneic mouse models using the murine squamous cell carcinoma cell line (SCCVII) are widely employed to investigate tumor‐induced bone involvement. However, SCCVII is not a clonal line, and phenotypic variability may arise among subclones. This study aimed to determine whether distinct SCCVII subclones exhibit different bone resorption patterns in gingival squamous cell carcinoma (GSCC) mouse models. Methods Syngeneic GSCC models were prepared by transplanting SCCVII subclones (A and B) into the mandibular ramus or calvarial periosteum of C3H/HeN mice, respectively. Bone resorption patterns were evaluated using micro‐computed tomography, histological analysis (including TRAP staining), and quantitative PCR. Results SCCVII subclones, maintained in two independent laboratories, were authenticated using short tandem repeat profiling. The GSCC mouse models of subclones exhibited distinct patterns of bone resorption. Radiographic analysis of the mandibular models showed that the bone resorption pattern of subclone A caused the depression of the mandibular cortical bone, whereas subclone B displayed a significantly aggressive bone resorption pattern and lacked continuity of the cortical bone owing to multiple invasions into the bone marrow. In the calvarial models, the perforated area in subclone B was 2.3‐fold larger than that in subclone A ( p < 0.01). Subclone B‐induced tumors showed significantly increased osteoclast number and diameter. TNF‐α and PTHrP expression levels were significantly upregulated in subclone B‐induced tumors, indicating their role in enhanced osteoclastogenesis. Conclusion This study shows that SCCVII subclonal heterogeneity leads to distinct bone resorption patterns in GSCC models, highlighting the need to consider cellular variability in experimental designs.