| IntroductionTelomerase activity is believed to be critical for cell senescence, apoptosis, immortalization and cancerization. Telomerase is a ribonu-cleoprotein DNA polymerase, which synthesizes telomerase DNA repeats and compensates for its loss with each cell division, participating cell immortalization. The structure of human telomerase has been determined to consist of an RNA template, human telomerase RNA component ( hTR) , and two associated proteins, human telomerase reverse transcripatase (hTERT) and human telomerse associated protein 1 ( hTPl). hTR and hTP1 exhibits no significant association with telomerase activity. However, hTERT is a putative catalytic subunit of telomerase, whose expression is closely correlated with telomerase activity in vitro and in vivo. Bcl - 2 has been demonstrated to regulate apoptosis. The relation of teloerase activity with bcl - 2 is controversial. But most scholars believe bcl - 2 regulates telomerase activity in human carcinoma cells. No evidence shows the relation of these two in ameloblastoma ( AB ) .AB is the most frequently occurring odontogenic tumor, the frequency of which is 59. 3% in china. AB is considered as a benign tumor by WHO. However, it may progressively invade the jaw, recur locally and transform malignantly. AB is therefore treated as a semi ?malignancy. In fact, after extirpation AB recurred in one of four patients. We detected expression of hTERT and bcl - 2 in AB and analyzed the correlation to investigate the molecular mechanisms in the regulation of telomerase, and study the relation of cell differentiation and its clinical biological behavior in AB to provide some theoretic basis for the diagnosis, therapy and prognosis of AB.Materials and methodsThe specimens used by in situ hybridization were surgically removed from 54 patients with AB (primary AB 31 cases, recurrent AB 17 cases, malignant AB 4 cases) , 16 patients with odontogenic ker-atocyst ( OKC ) and 7 patients with oral normal mucosa at the First Affiliated Hospital of China Medical University between 1996 -2001. All the 119 samples used in imrnunohistocheniical study were obtained from the patients admitted to Collage of Stomatology and the First Affiliated Hospital of China Medical University between 1897 - 2001, which included 75 cases of AB (primary AB 31 cases, recurrent AB 37 cases, malignant AB 7 cases) , 35 cases of OKC and 9 cases of o-ral normal mucosa. We detected hTERT by in situ hybridization, and bcl - 2 by S - P method and in situ hybridization. We used a scoring system to evaluate semiquantiatively the immunoexpression. With regard to In situ expression, the extent of staining was scored; ( - ) fewer than 5% positive or no staining; ( + ) 5% -24% positive; ( + + ) 25% -50% positive; ( + + + ) more than 50% of cell positive. SPSS for 10. 0 statistical software was used to solve the data. Chi -square test was used to analyze the correlation, and fishers exact test was used when the frequency of a cell in a 2 x2 table was <5. Kendall rank correlation was determined between telomerase activity andbcl -2 expression. The probability of P <0.05 was regarded as statistically significant.ResulthTERT mRNA was positive expressed judging purple granule in plasma. The expression of hTERT mRNA was negative or weaker in normal oral mucosa (14. 3%) , weaker or moderate in OKC (87. 5% ) , moderate or strong in AB (94. 4% ) , respectively. There was a significant difference in these three groups ( P <0.001) . The difference between primary, recurrent and malignant AB was significant ( P <0. 05). x2test indicated that there were no correlation in hTERT mRNA expression with age, sex, position and histological type ( P > 0.05).Bcl - 2 was strong positive expressed in the plasma and nuclear membrane of cell of 47 cases of AB, weaker in 19 AB, negative in 9 AB. The positive ratio of OKC, normal oral mucosa was 80% , 44. 4% , respectively. There was a significant statistical difference in these three groups ( P < 0. 001). hTERT mRNA was stronger as AB recurred... |
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