| Background and objective: Oromaxillofacial sarcoma is a rare, aggressive malignancy arising from mesenchymal tissue of oral and maxillofaxial region, and is charactered by high-grade malignancy, aggressive invasion, insignificant effect for combined therapy, and poor prognosis. It is essential for correct treatment decisions and better survival rates to make extensive research on the development mechanisms and the biological character of oromaxillofacial sarcoma. Telomerase activity is believed to be crucial for cell immortalization and cancerization, since most malignant cells express this activity. Of the three major comprising components, human telomerase reverse transcriptase (hTERT) has been shown to be rate-limiting determinant of the enzymatic activity of human telomerase. Expression of hTERT is observed at high levels in malignant tumors and cancer cells, but not in normal tissues or telomerase-negative cell lines. C-myc protein, a transcription factor encoded by the myc protooncogene, is also implicated in the positive regulation of hTERT expression. The ability of myc to activate telomerase may contribute to its ability to promote tumor formation. Little is known about the expression of hTERT gene, C-myc and ki-67 in oromaxillofacial sarcoma. The objective of this study is to investigate the expression of hTERT gene, C-myc and ki-67 in oromaxillofacial sarcoma, and evaluate their significance in the tumorigenesis anddevelopment of oromaxillofacial sarcoma. Materials and methods:1. 54 histologically diagnosed specimens were obtained from patients who underwent operation or biopsy at the first teaching hospital of zhengzhou university, including 37 sarcomas, 14 benign mesenchymal tumors and 3 normal mesenchymal tissues of oral and maxillofacial region. No patients had received preoperative chemotherapy or radiation therapy. The tissues were fixed in 10% formalin and embedded in paraffin.2. The expression of hTERTmRNA and the immunohistochemical expression of hTERT protein, C-myc and ki-67 were determined by in situ hybridization and immunohistochemistry respectively.3. The results were analyzed by SPSS 10.0 software wrap, and a P value of less than 0.05 was considered to be statistically significant.Results:1. The 37 sarcomas were classified ino 12 histologic categories, such as osteosarcoma, chondrosarcoma, leiomyosarcoma, malignant fibrous histiocytoma, synovial sarcoma, et al. Of 37 sarcomas, 12 sarcomas were grade I , 10 were grade II, and 15 were grade III; 18 specimens were primary tumors and the other 19 were locally recurrent tumors; at the time of presentation, 4 sarcomas had distant metastasis and 7 had lymph node metastasis, while the other specimens didn't.2. In oromaxillofacial sarcomas, positive staining for hTERTmRNA was intratumoral heterogeneous, diffuse and its positive rate was 62.16%; hTERTmRNA expression was detected in 14.29% of benign tumors, and a significant diffenence was found between the two groups (PO.05). In the three groups of grade I , grade II and grade III, the positive rates of hTERTmRNA were 41.67%, 50% and 86.67%, respectively. There was a significant difference between grade I and gradeIII(P<0.05). The expression level of hTERTmRNA was significantly higher in locally recurrent sarcomas than in primary sarcomas (P<0.05). In sarcomas with distant metastasis and/or lymph node metastasis, the positive expression of hTERTmRNA tended to increase compared to the other sarcomas, while no statistical significance was found (P>0.05).3. Expression of hTERT protein had a positive distribution similar to hTERTmRNA, and was detected in 19 of 23 cases that were positive for in situ hybridization. A significant correlation was found between the expression of hTERT mRNA and its protein in oromaxillofacial sarcoma(P<0.05). The expression level of hTRET protein was significantly increased in sarcomas compared to benign tumors (P<0.05), and tended to increase with pathological grades. hTERT expression was closely associated with pr...
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