| Cell proliferation follows an orderly progression through the cell cycle, which is governed by complex composed of cyclins and cyclin-dependent-kinase. Abnormal expression of cell cycle regulatory molecules may cause alterations in cell cycle resulting in an uncontrolled cell growth, a universal feature of neopla-sia. Gl phase to S phase progression is a key point of control in cell cycle . After Gl phase, the cell become largely independent of extracellular signals and progress automatically through subsequent cell cycle to the next Gl phase. It has been demonstrated that p16-cyclinDl-Rb pathway play an important role in regulation of Gl/S phase transition. In Gl phase, cyclinDl forms complex with CDK4/6 and results in phosphorylation inactivation of Rb, and then releases E2F to iuduce transcription of S-phase relative gene, and results in ceD division or transformation. P16 inhibits phosphorylation of Rb by compacting to binding CDK4/6 and prevents it from forming an active complex with cyclinDl, resulting in Gl phase cell arrested. However, the relationship between this pathway and AB is rarely studied.AB is the most frequently occurring odontogenic tumor and is a benign tumor. However, it may progressively invade the jaw, recur locally and transform malignantly. Although AB and OKC have been under intensive research, the molecular mechanism has not been completely clarified. We detected expression of cyclinDl and p16 at both transcript and protein levels in AB and OKC and analyzed the correlation , so as to identify the role of Rb pathway during the development of AB and to provide some theoretic basis for the diagnosis, therapy and prognosis of AB.Materials and methodsThe specimens used by in situ hybridization and immunohistochemical method were surgically removed from 54 patients with AB (primary AB 31 cases, recurrent AB 19 cases, malignant AB 4 cases) , 7 patients with odontogenic keratocyst ( OKC) at the First Affiliated Hospital of China Medical University between 1996-2001. We detected cyclinDl mRNA and p16 mRNA by in situ hybridization, and cyclinDl protein and p16 protein by S-P immunohistochemical method. The numbers of positive cells was used to evaluate the intensity of immunoexpression. With regard to in situ expression, the extent of staining was scored: (-) fewer than 10% positive or no staining; ( + ) 10%-40% positive; ( ++ ) 40%-70% positive; ( +++ ) more than 70% of cell positive. Chi-square test and analysis of variance were used to solve the data , and Kendall correlation was determined between cyclinDl mRNA and p16 mRNA expression. All statistical analysis was performed with SPSS 10.0 software package. The probability of P <0.05 was regarded as statistically significant.ResultCyclinDl mRNA and p16 mRNA was positive expressed judging purple granule in plasma. The expression of cyclinDl mRNA was weaker or moderate in OKC (42.9% ) , moderate or strong in AB (42. 6% ) , respectively; There was no significant difference in these tow groups ( P > 0.05 ). There was a stas-tiscal difference of the expression of cyclinDl mRNA and protein among primary , recurrent and malignant AB ( P < 0.05, P < 0. 01). We found cyclinDl protein was coincident with cyclinDl mRNA ( P < 0.05 ).Decreased expression of p16 mRNA in AB and OKC was found in this stud-y, and the negative expression rates were 85. 7% and 68.5% , respectively. As well as cyclinDl, there was a stastiscal difference of the expression of pi 6 mRNA and protein among primary, recurrent and malignant AB (P <0. 05). p!6 protein was also coincident with p16 mRNA ( P < 0. 05 ) , and its expression isrelated with cell differentiation. The proliferation and differentiation of the tumor cells were heterogeneity in AB.In current study, there was a negative correlation between p16 mRNA and cyclinDl mRNA expression in AB ( rk = -0. 342, P < 0. 01). x2test indicated that there were no significant differences between cyclinDl mRNA, p!6 mRNA expression and age, sex, position and histological type (P>0.05).DiscussionGl ph...
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