Co-expression of Ki-67 and p53 protein in ameloblastoma and keratocystic odontogenic tumor

Abstract

Objectives. The purpose of this study was to evaluate the cell proliferation and p53 protein expression in ameloblastomas (ABs), keratocystic odontogenic tumor (KCOT) and dentigerous cyst (DC). Method. The immunohistochemistry were carried out for Ki-67 and p53 protein expression by using MIB-1 clone and DO-7 clone, respectively, in ABs (n = 23), KCOT (n = 32), DC (n = 30), normal oral mucosa (NOM) (n = 12) and fetal oral mucosa (FOM) (n = 10). Results. Both the Ki-67 LI Labeling index (LI) and p53 LI was significantly higher in ABs than KCOT, DC, NOM and FOM. The Ki-67 LI and p53 LI was significantly higher in KCOT as compared to DC. Ki-67 LI and p53 LI was observed in descending order in ABs, KOCT, FOM, NOM and DC. There was significant correlation between Ki-67 expression and p53 expression in ABs, KCOT, DC and NOM. The densely stained p53 positive cells were noted higher in ABs than KCOT. The very few densely p53 positive cells were noted in DC, NOM and FOM. Conclusion. The results suggest that the p53 protein expression does not necessarily imply an association with malignant disease and/or p53 gene mutation, but a tendency to be expressed in an increasing quantitative and qualitative manner, as the biologic behavior of odontogenic cyst or tumors becomes more aggressive. p53 over-expression may promote cell proliferation in odontogenic lesions. Thus, it can be stipulated that Ki-67 and p53 protein expression can be used as a prognostic marker in odontogenic lesions.     

Co-expression of Ki-67 and p53 protein in ameloblastoma and keratocystic odontogenic tumor

Abstract Objectives. The purpose of this study was to evaluate the cell proliferation and p53 protein expression in ameloblastomas (ABs), keratocystic odontogenic tumor (KCOT) and dentigerous cyst (DC). Method. The immunohistochemistry were carried out for Ki-67 and p53 protein expression by using MIB-1 clone and DO-7 clone, respectively, in ABs (n = 23), KCOT (n = 32), DC (n = 30), normal oral mucosa (NOM) (n = 12) and fetal oral mucosa (FOM) (n = 10). Results. Both the Ki-67 LI Labeling index (LI) and p53 LI was significantly higher in ABs than KCOT, DC, NOM and FOM. The Ki-67 LI and p53 LI was significantly higher in KCOT as compared to DC. Ki-67 LI and p53 LI was observed in descending order in ABs, KOCT, FOM, NOM and DC. There was significant correlation between Ki-67 expression and p53 expression in ABs, KCOT, DC and NOM. The densely stained p53 positive cells were noted higher in ABs than KCOT. The very few densely p53 positive cells were noted in DC, NOM and FOM. Conclusion. The results suggest that the p53 protein expression does not necessarily imply an association with malignant disease and/or p53 gene mutation, but a tendency to be expressed in an increasing quantitative and qualitative manner, as the biologic behavior of odontogenic cyst or tumors becomes more aggressive. p53 over-expression may promote cell proliferation in odontogenic lesions. Thus, it can be stipulated that Ki-67 and p53 protein expression can be used as a prognostic marker in odontogenic lesions.     

Comparative analysis of tumour angiogenesis in solid multicystic and unicystic ameloblastoma by using CD 105 (endoglin)

Objective

The aim of the present study was to evaluate and compare the expression of CD105 (endoglin) in solid multicystic ameloblastoma (SMA) and unicystic ameloblastoma (UA).

Materials and methods

Angiogenesis was assessed in 20 SMA, 15 UA and 10 normal oral mucosa samples by measuring the mean vascular density (MVD), total vascular area (TVA) and mean vascular area (MVA). The immunohistochemistry was carried out by using monoclonal mouse anti-human antibody against CD105.

Results

The Kruskal–Wallis test showed significant difference in mean MVD, TVA, and MVA between SMA, UA, and control group (p < 0.001). Using the Mann–Whitney test, the mean MVD, TVA and MVA, was statistically significant between SMA and control group (p < 0.001) as well as between UA and control group (p < 0.001). No significant difference of mean MVD, TVA, and MVA, was observed between SMA and UA (p > 0.05).

Conclusion

Our study results show no significant difference in MVD, TVA and MVA between SMA and UA. This may reflect the fact that though clinical behaviour, histopathological presentation and prognosis of SMA and UA differ, the process of angiogenesis is not different. This suggests that the angiogenesis has an important role in tumour progression and invasiveness of ameloblastoma. Measurement and assessment of tumour angiogenesis may prove very valuable in predicting response to antiangiogenic therapeutic strategies and also provide objective assessment of post therapeutic response particularly in recurrent cases of SMA and UA.     

Prevalence of developmental odontogenic cysts in children and adolescents with emphasis on dentigerous cyst and odontogenic keratocyst (keratocystic odontogenic tumor)

Objective. To investigate the incidence and prevalence of developmental odontogenic cysts in children and adolescents and compare the features of the two most common types, dentigerous cyst and keratocystic odontogenic tumor (KCOT). Study design. A retrospective review in a series of 369 patients with all histological diagnoses of developmental odontogenic cysts in children (≤12 years) and adolescents (13–18 years) was conducted. Results. Among these, 361 (97.8%) patients were diagnosed as dentigerous cyst (n = 281) and KCOT (n = 80), with the male-to-female ratios of dentigerous cyst and KCOT both being 2:1. The average age of the patients with KCOT was older than that of those with dentigerous cyst (14.7 years vs 11.8 years, p < 0.001). Dentigerous cyst (59.1%) was more common in children, but KCOT (78.8%) was more common in adolescents (p < 0.001). Dentigerous cyst (57.6%) predominantly located on the maxilla, but KCOT (60.3%) predominantly located on the mandible (p = 0.010). Conclusions. Adolescent patients with lesions located on the mandible would favor KCOT over dentigerous cyst. This study aids in better knowledge of the prevalence of developmental odontogenic cysts in a large pediatric population, and shows that a well-supported early diagnosis is indispensable for a more adequate treatment.     

Syndecan‐1 (CD 138) surface expression marks cell type and differentiation in ameloblastoma,keratocystic odontogenic tumor,and dentigerous cyst

J Oral Pathol Med (2013) 42 : 186–193 Background: The altered expression of syndecan‐1 (SD‐1), a transmembrane heparan sulfate proteoglycan, in ameloblastomas and cysts of odontogenic origin suggests that this molecule could have prognostic value in assessing the clinical outcome of those lesions. The purpose of this study was to analyze SD‐1 expression profile immunohistochemically in archival, paraffin‐embedded tissue sections of ameloblastomas and in common odontogenic cysts arising from the same locale. Methods: SD‐1 expression was investigated in 32 ameloblastomas, 26 keratocystic odontogenic tumors (KCOT), and 21 dentigerous cysts from the archives of the histopathology laboratory which were routinely processed. The cases were reviewed and assessed according to the established criteria. Sections were immunostained with monoclonal antibody against SD‐1 (CD138). Sections of normal oral mucosa, site matched, were stained in parallel as positive controls. The plasma cells in sections served as internal positive controls. Results: SD‐1 expression was observed in the epithelial and stromal elements of the sections, and the expression was significantly associated with the lesion’s extension and involvement of adjacent structures (P = 0.025). Stellate‐reticulum cells showed higher expression than the ameloblasts, which was at a significant level (P < 0.0001). Highly significant difference was reported among the three groups of lesion for the epithelial staining (P < 0.0001). The mean rank scores (Kruskal–Wallis test) of ameloblastomas were significantly lower than those of KCOT and dentigerous cysts. Non‐significant comparison was made between KCOT and dentigerous cyst groups. Conclusions: The present study revealed SD‐1 immunoreactivity in the stromal cells of ameloblastoma, KCOT, and dentigerous cysts rather uniformly. This reported SD‐1 expression by the tumor stroma is considered to be associated with poor prognosis of the lesions.     

EGFR and Ki‐67 expression in oral squamous cell carcinoma using tissue microarray technology

J Oral Pathol Med (2010) 39 : 571–578 Objective: Our aim was to validate the use of tissue microarrays (TMA) in oral squamous cell carcinomas (OSCC) to analyse epidermal growth factor receptor (EGFR) and Ki‐67 expression. We also analysed the relationship that the expression of these markers may have with clinical, pathological and survival variables. Patients and methods: The study sample comprised 39 unselected patients diagnosed and treated for OSCC. We analysed Ki‐67 and EGFR expression by immunohistochemistry on formalin‐fixed, paraffin‐embedded surgical specimens. Whole sections (WS) were compared with double 1.5 mm core‐tissue microarrays. Results: High EGFR expression was observed both on TMA (in 98% of the cases) and WS (in 100% of the cases) with substantial agreement kappa value (0.720). EGFR expression was not significantly associated with clinical, pathological and survival variables on TMA and WS. Ki‐67 analysis showed a Spearman correlation of 0.741 with a Ki‐67 mean labelling index of 45% in TMA and 56.8% in WS. We found a significant relationship between gender and Ki‐67 labelling index on WS (P = 0.022) and TMA (P = 0.002). Clinical stage was the only parameter in multivariate analysis that had a significant predictive value. Conclusion: We demonstrate that dual 1.5 mm core TMA is a valid, rapid, economical and tissue‐saving way to study OSCC biopsies and that it presents strong correlation with the WS. EGFR overexpression in OSCC suggests that these tumours may be a candidate for therapy investigation directed to EGFR.     

Immunohistochemical detection of Ki‐67 is not associated with tumor‐infiltrating macrophages and cyclooxygenase‐2 in oral squamous cell carcinoma

J Oral Pathol Med (2010) 39 : 565–570 Background: An inflammatory component consisting of cells and chemical mediators may influence the proliferation and dissemination of the oral squamous cell carcinoma (OSCC). In the present study, we evaluated the possible relationship between Ki‐67, tumor‐associated macrophages (TAMs), and COX‐2 in OSCCs. In addition, the immunodetection of these proteins was associated with different histological grades of malignancy, including invasive and in situ tumors. Methods: Twenty‐seven OSCC cases were examined by light microscopy using criteria adopted WHO, and immunohistochemistry for Ki‐67, CD68, and COX‐2 using EnVision System in invasive and in situ lesions. Immunohistochemical detection of these proteins was assessed and scored for COX‐2, and results were compared with their histological grades of malignancy. Results: A correlation between Ki‐67, COX‐2, and CD68 was not found. Histological grade of malignancy (HDM) was associated with the Ki‐67 immunostaining (P = 0.00), but this was not observed regarding both CD68 (P = 0.51) and COX‐2 (P = 0.89). Furthermore, there was a COX‐2 overexpression in 62.96% of the sample, and a high density of TAMs in both OSCCs and in situ carcinomas. Conclusions: Imunolabeling for Ki‐67 was directly correlated with less‐differentiated tumors, suggesting that this marker may contribute to understand the biological behavior of OSCC, and help to distinguish risk groups of OSCC. Furthermore, the lack of correlation between Ki‐67, COX‐2, and CD68 indicates that the latter two markers may play a pivotal role in oral carcinogenesis. However, further studies are needed to clarify their contribution for cell proliferation and tumor differentiation.     

Odontogenic keratocyst expresses vascular endothelial growth factor: an immunohistochemical study

Background:  Vascular endothelial growth factor (VEGF) expression may act as a sensitive measure of the angiogenic potential of a lesion. Furthermore, VEGF has been implicated in the pathogenesis of cystic tumors and inflammatory odontogenic cysts. Thus, we studied the expression of VEGF in the epithelium of odontogenic keratocyst (OK) in association with cell proliferation and apoptosis.
Methods:  Forty-two cases of OK, 26 cases of dentigerous cyst (DC), and 15 cases of residual cyst (RC) were retrospectively examined by immunohistochemistry for VEGF, Ki67/Mib-1 and anti-caspase-3. For VEGF and caspase-3, the intensity of immunostaining was qualitatively assessed, while for the evaluation of Ki67 the average number of positively stained nuclei in 10 high-power microscopic fields (×400) was calculated.
Results:  The VEGF expression was stronger in OK when compared with DC ( P  < 0.007). The rate of nuclear Ki67 expression in OK was significantly higher than that in DC ( P  < 0.001) and RC ( P  < 0.001). Cytoplasmic caspase-3 expression was statistically more intense in RC than in OK ( P  = 0.001) or DC ( P  < 0.001). A statistically significant correlation was seen in OK for Ki67 ( P  < 0.001) and VEGF ( P  = 0.023), but not for caspase-3. Multiple regression analysis revealed a linear relationship between VEGF and Ki67.
Conclusions:  The VEGF was expressed in the epithelium of OK, DC, and RC with a variable intensity, and in OK VEGF expression was related to Ki67. It is suggested that VEGF expression by the odontogenic epithelium is not induced solely by inflammation.     

Actual Proliferating Index and p53 protein expression as prognostic marker in odontogenic cysts

Background:  The purpose of this study was to evaluate the biological aggressiveness of odontogenic keratocyst/keratocystic odontogenic tumour (KCOT), radicular cyst (RC) and dentigerous cyst (DC) by observing the actual proliferative activity of epithelium, and p53 protein expression.
Methods:  The actual proliferative activity was measured by Ki-67 Labelling Index and argyrophilic nucleolar organizing regions (AgNOR) count per nucleus. The p53 protein expression was also evaluated.
Results:  Ki-67 positive cells were observed higher in suprabasal cell layers of KCOT with uniform distribution, a few of them were predominantly observed in basal cell layer in RC and DC. The AgNOR count was significantly higher in suprabasal cell layers of KCOT. The actual proliferative activity was noted to be higher in suprabasal cell layers of KCOT. The p53 immunolabelling was dense and scattered in basal and suprabasal cell layers in KCOT. The weakly stained p53 positive cells were observed diffusely distributed in KCOT, whereas they were mainly seen in basal cell layer of RC and DC.
Conclusion:  The quantitative and qualitative differences of the proliferative activity and the p53 protein expression in sporadic KCOT may be associated with intrinsic growth potential that could play a role in its development and explain locally aggressive biological behaviour. AgNOR count and p53 protein detection in odontogenic lesions can be of great consequence to predict the biological behaviour and prognosis.     

The growth and osteoclastogenic effects of fibroblasts isolated from keratocystic odontogenic tumor

Oral Diseases (2012) Objectives: To investigate the growth characteristics and effects on osteoclastogenesis in fibroblasts isolated from keratocystic odontogenic tumor (KCOT) fibrous capsule. Materials and Methods: Fibroblasts isolated from KCOT fibrous capsule and normal gingival mucosa were cultured in vitro. Their colony‐forming units and proliferative activity were investigated, and the osteoclastogenic effects were also observed by a co‐culture system with osteoclast precursor cell line Raw264.7. The mRNA of several genes related to bone resorption (IL‐6, VEGF, COX‐2, and M‐CSF) was analyzed by real‐time PCR. Results: Keratocystic odontogenic tumor fibroblasts developed fewer CFU and had longer population doubling time than gingival fibroblasts (P < 0.05). In contrast to gingival fibroblasts, KCOT fibroblasts expressed less IL‐6, COX‐2, and M‐CSF (P < 0.05); however, the Raw264.7 co‐cultured with KCOT fibroblasts developed more osteoclast‐like cells and expressed higher level of nfatc1 than that co‐cultured with gingival fibroblasts. Increased COX‐2 expression and VEGF expression were detected in KCOT fibroblasts and Raw264.7 co‐culture system (P < 0.05). Conclusion: Although KCOT fibroblasts showed lower level of cell proliferation than gingival fibroblasts, higher osteoclastogenic ability was detected when co‐cultured with Raw264.7. These results suggest that the cell–cell interaction in the co‐culture system, possibly by increasing COX‐2 and VEGF expression, may be responsible for the increased osteoclastogenic effects of KCOT fibroblasts.     

DNA replication licensing factor MCM2, geminin,and Ki67 define proliferative state and are linked with survival in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is still an unabated global killer with little advancement in its survival rate. DNA replication licensing proteins and Aurora kinase A are biomarkers that play important roles in genomic stability. The expression profile of minichromosomal maintenance protein 2 (MCM2), Ki67, geminin, and Aurora‐A were linked to clinicopathological and outcome parameters, survival, and DNA content in 125 cases of OSCC. Oral fibroepithelial polyps (OFEP) were controls. The OSCC tumour cells were in a rapidly proliferating state, as assessed by the increased expression profile of MCM2, Ki67, geminin, and Aurora‐A and of the geminin/Ki67 ratio, and the decrease of the MCM2/Ki67 ratio, in OSCC compared with OFEP (P < 0.000). There was an association between expression of MCM2, Ki67, and geminin and tumour histologic and invasive front grade (P < 0.05). A total of 82% of the OSCC assessed had aneuploid DNA content, which was associated with increased expression intensity of Aurora‐A (P = 0.01). Geminin and the geminin/Ki67 ratio were associated with TNM staging (P < 0.05), and weak expression of MCM2, Ki67, geminin, and Aurora‐A were predictive of OSCC survival (P < 0.05). Dysregulation of the origin licensing pathway and the mitotic pathway are important events in OSCC, and the combined analysis of these proteins may contribute to improved treatment decisions.     

Metallothionein in the radicular,dentigerous, orthokeratinized odontogenic cysts and in keratocystic odontogenic tumor

J Oral Pathol Med (2011) 40 : 270–276 Background: Metallothionein (MT) is a protein correlated with cellular differentiation and proliferation, as well as with the inhibition of apoptosis. The aims were to report and to compare the MT expression in odontogenic cysts and keratocystic odontogenic tumor (KOT); to correlate the MT with cellular proliferation; and to evaluate the influence of the inflammation in MT. Methods: Nine cases of radicular cyst (RC), nine dentigerous cyst (DC), four orthokeratinized odontogenic cyst (OOC), and eight KOT were submitted to immunohistochemistry using anti‐MT and anti‐Ki‐67. Indexes of MT (IMT) and Ki‐67 (IK) were obtained. Lesions were grouped according to inflammation: mild‐to‐moderate (group A) and intense (group B). Results: IMT proved to be highest in RC (91%), followed by DC (89%), KOT (78%), and OOC (63%). IMT was inversely correlated with IK in KOT, and OCC, but was positively correlated with RC and DC. No differences in IMT and in IK could be observed between groups A and B. Conclusions: The higher IMT found in RC and DC compared to OCC and KOT, as well as the differences between the last ones, is possibly correlated with their different histopathological features and clinical behavior. In RC and DC, MT may play a role in cellular proliferation. However, it seems that MT is either less or is not related to proliferation in OOC and in KOT. Moreover, inflammation does not seem to alter IMT and IK.     

The effect of internal versus external abutment connection modes on crestal bone changes around dental implants: a radiographic analysis

Background: To the best of our knowledge, the influence of external versus internal implant–abutment connections on crestal bone remodeling has not been reported. The aim of the present study is to investigate the influence of the abutment connection on peri‐implant crestal bone levels (CBLs) using radiographic recordings. Methods: Radiographic recordings from 40 single‐tooth implants (20 external and 20 internal octagonal connections; one implant/patient) in 40 patients (15 males and 25 females; mean age: 54.3 years) were selected for analyses. The radiographic evaluation included the following: 1) linear bone change (LBC); 2) dimensional change (DC); and 3) angle between the implant and adjacent bone (AIB). Differences in LBC, DC, and AIB between implant placement and 1 year after loading for each system were evaluated using a paired t test. Comparison of LBC, DC, and AIB between systems at 1 year after loading was done using analysis of covariance. The significance level was set at P ≤0.05. Results: Radiographic CBLs (LBCs) were reduced at 1 year after loading compared to those at implant placement to reach statistical significance for the external connection (P = 0.000) but not the internal connection (P = 0.939). CBL changes were significantly greater for the external compared to the internal connection (P = 0.000). Similarly, the DC for the external connection was significantly greater compared to that for the internal connection (P = 0.004). Conclusion: Within the limitations of this study, the implant–abutment connection technology appears to have a significant impact on peri‐implant CBLs, with the external connection paralleled by a significant reduction of CBLs.     

Is podoplanin expression associated with the proliferative activity of ameloblastomas?

Oral Diseases (2012) 18 , 673–679 Objectives: The aim of this study was to investigate the relationship between podoplanin expression and proliferative activity of ameloblastomas and remnants of the odontogenic epithelium from dental follicles (DF) of unerupted teeth. Subjects and methods: Thirty‐three paraffin‐embedded ameloblastomas and thirty‐two DF obtained of unerupted teeth were analyzed by immunohistochemistry using anti‐human podoplanin and anti‐Ki‐67 antibodies. Podoplanin expression in odontogenic epithelial cells was evaluated using a scoring method, and the Ki‐67 labeling index was determined by the percentage of positive odontogenic cells. Results: All ameloblastomas displayed podoplanin expression in ameloblast‐like cells of the epithelial islands. Membranous expression of podoplanin in ameloblastomas was stronger than in the remnants of odontogenic epithelium (P = 0.001). Statistically significant difference was observed between the cytoplasmic and membranous expression of podoplanin in the remnants of odontogenic epithelium (P = 0.001). The index of epithelial odontogenic proliferative activity, verified by Ki‐67 expression, was higher in ameloblastomas vs remnants of odontogenic epithelium (P < 0.001). No statistically significant correlation was identified between podoplanin and the cellular odontogenic proliferative activity in ameloblastomas and DF (P > 0.05). Conclusions: These results provide evidence that there is no connection between podoplanin immunostaining and odontogenic cellular proliferative activity and suggest a role for membranous podoplanin expression in the local invasion of ameloblastomas.     

A comparative study of epithelial cell proliferation between the odontogenic keratocyst, orthokeratinized odontogenic cyst, dentigerous cyst, and ameloblastoma

OBJECTIVES: The aim of the present study was to compare the proliferation index of the epithelial cells between odontogenic keratocysts (OKC), orthokeratinized odontogenic cysts (OOC), dentigerous cysts (DC), and ameloblastomas. MATERIALS AND METHODS: The proliferation index, employing a novel cell proliferation marker IPO-38, was studied by the immunohistochemical technique in 10 OKC, seven OOC, eight DC and 10 ameloblastomas. RESULTS: The ameloblastoma had no higher labeling index (LI) of IPO-38 than the OKC (P = 0.910) but had higher LI than the OOC (P = 0.001) and DC (P = 0.000); the OKC had higher LI than the OOC (P = 0.002) and DC (P = 0.000); and the OOC had higher LI than the DC (P = 0.011). IPO-38-positive cells in the OKC and OOC were located principally in the suprabasal cell layers while the ameloblastoma were found in the peripheral portion in particularly, the follicular and plexiform types. CONCLUSION: These findings support previous studies that the proliferation indices are useful in predicting the different biological behavior of the odontogenic lesions and the OKC should be regarded as a benign tumor rather than simply an odontogenic cyst.     

Epithelial cell proliferation in odontogenic keratocysts: a comparative immunocytochemical study of Ki67 in simple, recurrent and basal cell naevus syndrome (BCNS)-associated lesions

The aim of the present study was to investigate epithelial cell proliferation in the linings of odontogenic cysts, including three different subtypes of odontogenic keratocyst (OKC), namely simple (non-recurrent), recurrent and basal cell naevus syndrome (BCNS)-associated lesions. Ki67 immunoreactivity in OKC (simple, n = 10; recurrent, n = 8; syndrome, n = 9), dentigerous cysts (DC, n = 5), radicular cysts (RC, n = 5) and normal oral mucosa (n = 7) was studied using a biotin-streptavidin-peroxidase method on paraffin sections after microwave treatment. Ki67⁺ epithelial cells were counted manually and related to the length of basement membrane (BM) as determined by TV image analysis. Data were analysed by the Mann-Whitney U test. The number of Ki67+ cells in simple OKC linings (53.1 ± 17.8 cells/ mmBM) was similar to that in oral epithelium (42.5 ± 12.7 cells/mmBM; P>0.2). However, both contained significantly more Ki67+ cells than DC (3.9 ± 1.3 cells/ mmBM) and RC linings (6.7 ±4.8 cells/mmBM; P<0.006). The epithelial distribution of Ki67⁺ cells differed between groups, with the percentage of positive cells in basal layers in OKC linings (7.0 ± 2.1%) being significantly lower than that of oral epithelia (35.9 ± 5.6%), DC (78.4 ± 8.4%) and RC (80.6 ± 7.7%) linings respectively (P<0.003). Comparison of Ki67 expression within the OKC group revealed no significant difference between simple and recurrent lesions (44.0 ± 13.8 cells/ mmBM; P>0.3). However, OKC associated with BCNS contained significantly higher numbers of Ki67+ cells (91.8±35.6 cells/mmBM; P<0.01). There was no difference in epithelial distribution of positive cells between the OKC groups. The results are consistent with OKC having a greater proliferative capacity than DC and RC and that its recurrence is not associated with a subgroup of lesions exhibiting increased proliferation. The increased proliferation in OKC associated with BCNS presumably reflects the underlying genetic defect(s) in this syndrome.     

Ras gene mutation is not related to tumour invasion during rat tongue carcinogenesis induced by 4‐nitroquinoline 1‐oxide

J Oral Pathol Med (2011) 40 : 325–333 Background: The aim of this study was to investigate whether mutations in the genes H‐ras and K‐ras were related to the mechanism of invasion as a result of the immunoexpression of H‐Ras, Ki‐67, alpha‐smooth muscle actin (SMA) and vascular endothelial growth factor (VEGF) during 4‐nitroquinoline 1‐oxide (4NQO)‐induced rat tongue carcinogenesis. Methods: Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12 and 20 weeks. Ten animals were used as negative control. Results: Although no histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure, Ki‐67 was overexpresssed in the ‘normal’ oral epithelium. In pre‐neoplastic lesions at 12 weeks following carcinogen exposure, the levels of Ki‐67 were increased (P < 0.05) when compared to negative control. Ki‐67, alpha‐SMA and VEGF were also overexpressed in squamous cell carcinomas induced after 20 weeks of treatment with 4NQO. No significant statistical differences (P > 0.05) were found in H‐ras protein expression for all experimental periods evaluated that corresponded to normal oral mucosa, hyperplasia, dysplasia and squamous cell carcinomas. In the same way, no mutations in H‐ras or K‐ras genes were found. Conclusions: Our results support the idea that expression of Ki‐67 plays a crucial role during malignant transformation being closely related to neoplastic conversion of the oral mucosa cells. However, it seems that mutations in the ras genes are not involved to experimental tongue carcinogenesis induced by 4NQO.     

Head and neck squamous cell carcinoma in non‐smoking and non‐drinking patients with multiple tumors: etiologic significance of p53 and Ki‐67 in non‐tumorous epithelium

Background: Non‐smoking and non‐drinking patients with head and neck squamous cell carcinoma have different clinical characteristics than their smoking and drinking counterparts. They are predominantly older female patients with oral cavity tumors, however, both groups show the same percentage of second primary tumors. Expression of tumor suppressor gene p53 and proliferation marker Ki‐67 in mucosal epithelial cells was analyzed to study whether biomarker expression is associated with a history of smoking and drinking and with single and multiple tumors. Methods: Non‐smoking and non‐drinking patients with multiple (n = 18) and single tumors (n = 15), smoking and drinking patients with multiple (n = 15) and single tumors (n = 14) were selected. For all groups, p53 and Ki‐67 expression patterns in non‐tumorous (tumor‐adjacent) mucosa including positivity of dispersed single cells and clusters for p53 and for suprabasal expression of Ki‐67 were immunohistochemically analyzed and compared. Results: p53 expression was significantly higher in users of tobacco and alcohol than in non‐users. Ki‐67 expression was not affected by tobacco and alcohol usage. Both Ki‐67 and p53 were similarly expressed in the groups with single and multiple tumors and hence not significantly related to the number of tumors. Conclusions: Non‐smoking and non‐drinking patients with squamous cell carcinoma have the same risk for developing multiple tumors as their smoking and drinking counterparts. As this occurs without an increased expression of p53 or Ki‐67, the significance of these proteins as biomarkers indicating pre‐malignant mucosal alterations is doubtful. Further research is needed to clarify this predisposition for developing multiple head and neck cancer.     

LINE‐1 methylation difference between ameloblastoma and keratocystic odontogenic tumor

Oral Diseases (2010) 16 , 286–291 Objective: Global hypomethylation is a common epigenetic event in cancer. Keratocystic odontogenic tumor (KCOT) and ameloblastoma are different tumors but posses the same tissue in origin. Here, we investigated long interspersed nuclear element‐1 (LINE‐1 or L1) methylation status between ameloblastoma and KCOT. Materials and methods: We studied the methylation levels of the long interspersed nucleotide element‐1 (LINE‐1) in ameloblastoma and KCOT. After collecting ameloblastoma cells and epithelium lining cells of KCOT by laser capture microdissection from paraffin embedded tissue, combined bisulfite restriction analysis of LINE‐1 (COBRALINE‐1) was performed to measure LINE‐1 methylation levels. Results: The LINE‐1 methylation level in KCOT (53.16 ± 12.03%) was higher than that in ameloblastoma (36.90 ± 16.52%), with a statistical significance of P = 0.001. The ranges of LINE‐1 methylation of both lesions were not associated with either age or sex. Conclusion: We found LINE‐1 hypomethylation levels between ameloblastoma and KCOT are different. Therefore, global methylations between these tumors are processed differently.     

Survivin、Ki67在牙源性囊肿上皮组织中的表达及意义

目的：探讨根端囊肿、含牙囊肿及角化囊肿衬里上皮中Survivin、Ki67的表达及意义。方法：采用免疫组化法检测12例根端囊肿、20例含牙囊肿、22例角化囊肿中Survivin、Ki67表达水平,并加以分析。结果：Survivin在根瑞囊肿中无表达,在含牙囊肿和角化囊肿中表达的阳性率分别为10％、63．6％,角化囊肿OD值显著高于根端囊肿和含牙囊肿（P〈0．05）;Ki67在3种组织中均有表达,角化囊肿中Ki67-ＬＩ显著高于根端囊肿和含牙囊肿（Ｐ〈0．05）;角化囊肿中Survivin阳性表达的Ki67-LI显著高于表达阴性者（Ｐ〈0．05）,且Survivin表达与Ki67表达呈正相关（r=0．452,P〈0．05）。结论：survivin、Ki67在牙源性囊肿中的表达差异显示了它们具有不同的增殖和分化过程。