Recurrent central odontogenic fibroma in a patient with nevoid basal cell carcinoma syndrome: case report and in vitro analysis.

OBJECTIVE: Central odontogenic fibromas (COF) are rare, benign tumors derived from dental mesenchymal tissue that may occur in the maxilla or mandible. This report describes primary and recurrent COF in the mandible of a patient with nevoid basal cell carcinoma syndrome (NBCCS). STUDY DESIGN: A 36-year-old African American male presented with a COF and its recurrence 17 months later. Tissue pieces were obtained from both occurrences with IRB-approved signed consent. Collected tissue pieces were dissected; one portion was formalin-fixed and paraffin-embedded, and the other was cultured for the isolation of cell populations from the primary (COdF-1) and recurrent (COdF-1a) tumors. Quantification real-time polymerase chain reaction (qRT-PCR), immunohistochemistry, and DNA sequencing were used for gene and protein analysis of the primary tumor and cell populations. RESULTS: Histopathologic analysis of the tumor showed sparse odontogenic epithelial cords in fibrous connective tissue, and qRT-PCR analysis of tumor and cell populations (COdF-1 and COdF-1a) detected VIM, CK14, CD34, CD99 and ALPL mRNA expression. Protein expression was confirmed by immunohistochemistry. CD34 expression in primary tissues was higher than in tumor cells due to tumor vascularization. DNA sequencing indicated the patient had PTCH1 mutations. CONCLUSIONS: Histopathology, mRNA, and protein expression indicate the rare occurrence of COF in a patient with mutated PTCH1 gene and NBCCS.

Runx2 deletion in hypertrophic chondrocytes impairs osteoclast mediated bone resorption.

Deletion of Runx2 gene in proliferating chondrocytes results in complete failure of endochondral ossification and perinatal lethality. We reported recently that mice with Runx2 deletion specifically in hypertrophic chondrocytes (HCs) using the Col10a1-Cre transgene survive and exhibit enlarged growth plates due to decreased HC apoptosis and cartilage resorption. Bulk of chondrogenesis occurs postnatally, however, the role of Runx2 in HCs during postnatal chondrogenesis is unknown. Despite limb dwarfism, adult homozygous (Runx2HC/HC) mice showed a significant increase in length of growth plate and articular cartilage. Consistent with doubling of the hypertrophic zone, collagen type X expression was increased in Runx2HC/HC mice. In sharp contrast, expression of metalloproteinases and aggrecanases were markedly decreased. Impaired cartilage degradation was evident by the retention of significant amount of safranin-O positive cartilage. Histomorphometry and µCT uncovered increased trabecular bone mass with a significant increase in BV/TV ratio, trabecular number, thickness, and a decrease in trabecular space in Runx2HC/HC mice. To identify if this is due to increased bone synthesis, expression of osteoblast differentiation markers was evaluated and found to be comparable amongst littermates. Histomorphometry confirmed similar number of osteoblasts in the littermates. Furthermore, dynamic bone synthesis showed no differences in mineral apposition or bone formation rates. Surprisingly, three-point-bending test revealed Runx2HC/HC bones to be structurally less strong. Interestingly, both the number and surface of osteoclasts were markedly reduced in Runx2HC/HC littermates. Rankl and IL-17a ligands that promote osteoclast differentiation were markedly reduced in Runx2HC/HC mice. Bone marrow cultures were performed to independently establish Runx2 and hypertrophic chondrocytes role in osteoclast development. The culture from the Runx2HC/HC mice formed significantly fewer and smaller osteoclasts. The expression of mature osteoclast markers, Ctsk and Mmp9, were significantly reduced in the cultures from Runx2HC/HC mice. Thus, Runx2 functions extend beyond embryonic development and chondrocyte hypertrophy by regulating cartilage degradation, osteoclast differentiation, and bone resorption during postnatal endochondral ossification.

Fluorescently Labeled Cetuximab-IRDye800 for Guided Surgical Excision of Ameloblastoma: A Proof of Principle Study.

PURPOSE: Fluorescently labeled epidermal growth factor receptor (EGFR) antibodies have successfully identified microscopic tumors in multiple in vivo models of human cancers with limited toxicity. The present study sought to demonstrate the ability of fluorescently labeled anti-EGFR, cetuximab-IRDye800, to localize to ameloblastoma (AB) tumor cells in vitro and in vivo. MATERIAL AND METHODS: EGFR expression in AB cells was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry. Primary AB cells were labeled in vitro with cetuximab-IRDye800 or nonspecific IgG-IRDye800. An in vivo patient-derived xenograft (PDX) model of AB was developed. The tumor tissue from 3 patients was implanted subcutaneously into immunocompromised mice. The mice received an intravenous injection of cetuximab-IRDye800 or IgG-IRDye800 and underwent imaging to detect infrared fluorescence using a Pearl imaging system (LI-COR Biosciences, Lincoln, NE). After resection of the overlying skin, the tumor/background ratios (TBRs) were calculated and statistically analyzed using a paired t test. RESULTS: EGFR expression was seen in all AB samples. Tumor-specific labeling was achieved, as evidenced by a positive fluorescence signal from cetuximab-IRDye800 binding to AB cells, with little staining seen in the negative controls treated with IgG-IRDye800. In the animal PDX model, imaging revealed that the TBRs produced by cetuximab were significantly greater than those produced by IgG on days 7 to 14 for AB-20 tumors. After skin flap removal to simulate a preresection state, the TBRs increased with cetuximab and were significantly greater than the TBRs with the IgG control for PDX tumors derived from the 3 patients with AB. The excised tissues were embedded in paraffin and examined to confirm the presence of tumor. CONCLUSIONS: Fluorescently labeled anti-EGFR demonstrated specificity for AB cells and PDX tumors. The present study is the first report of tumor-specific, antibody-based imaging of odontogenic tumors, of which AB is one of the most clinically aggressive. We expect this technology will ultimately assist surgeons treating AB by helping to accurately assess the tumor margins during surgery, leading to improved long-term local tumor control and less surgical morbidity.