Expression of cdk6 in head and neck squamous cell carcinoma.

OBJECTIVE: Cdk6 is a key regulator during the G1/S cell cycle transition. Aberrant expression of cdk6 protein has been observed in many cancer types. However, little is known about the expression of cdk6 in head and neck squamous cell carcinoma (HNSCC) and its clinical significance. This study evaluated the expression of cdk6 in HNSCC and analyzed the relationship between cdk6 expression and clinicopathological parameters of HNSCC. MATERIALS AND METHODS: Expression of cdk6 was immunohistochemically investigated in 98 HNSCCs. Nuclear and cytoplasmic positive cells were counted separately. Data were presented as the percentage of positive cells. The correlation between the percentage of positive cells and clinicopathological factors was determined. RESULTS: Nuclear and cytoplasmic staining for cdk6 were detected in 91 cases and 97 cases, respectively. A significant correlation was found only between the percentage of nuclear positive cells and T classification (p value = 0.0410). Tumors with high nuclear cdk6-positive cells showed a linear trend toward advanced tumor status (p value = 0.0064). CONCLUSIONS: Cdk6 was highly expressed in HNSCC. Tumors with high nuclear cdk6 expression tended to have advanced tumor status. These results suggest that cdk6 plays a vital role in HNSCC and is involved in tumor progression of this cancer. CLINICAL RELEVANCE: An increased nuclear cdk6 expression is an unfavorable factor for HNSCC. Cdk6 may serve as a therapeutic target in this cancer.

Aberrant expression of p-Smad3 in oral carcinogenesis.

OBJECTIVE: Smads are the keys of transforming growth factor ß (TGFß) signaling cascade and play a crucial role in many cancers. Once TGFß receptors are activated, Smad2 and Smad3 are phosphorylated and form complexes with Smad4. These complexes translocate from the cytoplasm to the nucleus where they regulate the target genes. The subcellular localization of phosphorylated Smad3 (p-Smad3) in oral carcinogenesis has never been reported. This study investigated the subcellular distribution of p-Smad3 in oral squamous cell carcinoma (OSCC) and oral leukoplakia (OL) with and without dysplasia. MATERIALS AND METHODS: Expression of p-Smad3 was immunohistochemically examined in 150 samples including OSCC, OL with and without dysplasia, and normal mucosa (NM). Cytoplasmic and nuclear positive cells were counted separately. The results were present as the frequency of positive cases. RESULTS: Cytoplasmic and/or nuclear staining for p-Smad3 was detected. The frequency of cytoplasmic expression in OL with dysplasia was significantly higher than that in NM. The numbers of cytoplasmic expression and cytoplasmic plus nuclear expression in OSCC were significantly higher than those in NM and OL with and without dysplasia. CONCLUSIONS: The overexpression of cytoplasmic p-Smad3 in OL with dysplasia and in OSCC suggests that p-Smad3 is in the nonfunctional state. Thus, the growth inhibitory effect of p-Smad3 is diminished during oral carcinogenesis. The cytoplasmic plus nuclear staining of p-Smad3 was aberrant in OSCC. CLINICAL RELEVANCE: The cytoplasmic staining of p-Smad3 may serve as a marker for oral premalignant lesions whereas the cytoplasmic plus nuclear staining of p-Smad3 may serve as a marker for OSCC.

Overexpression of survivin and caspase 3 in oral carcinogenesis.

Survivin is an inhibitor of apoptosis protein that inhibits caspase 3 function. While cytoplasmic survivin suppresses apoptosis, nuclear survivin regulates cell division. Little is known about the subcellular localization of survivin in oral carcinogenesis. This study examined the subcellular distribution of these 2 proteins in oral squamous cell carcinoma (OSCC) and premalignant lesions including oral leukoplakia (OL) with and without dysplasia. Expression of survivin and caspase 3 were immunohistochemically analyzed in 114 samples including OSCC, OL with and without dysplasia, and normal oral mucosa (NM). Cytoplasmic and nuclear positive cells were counted separately. The results were presented as the frequency of positive cases. The positive expression rates of cytoplasmic and nuclear survivin in OSCC were significantly higher than in NM, OL with and without dysplasia. NM showed a low rate of cytoplasmic survivin expression compared to OL with and without dysplasia. The numbers of cytoplasmic and nuclear expression of caspase 3 in OSCC were significantly higher than that of NM, OL with and without dysplasia. In conclusion, the overexpression of cytoplasmic survivin in OSCC and premalignant lesions suggest that suppression of apoptosis by survivin occurs at early and late stages of oral carcinogenesis. The elevated expression of nuclear survivin and caspase 3 in OSCC indicate that at the late stage survivin increases cell proliferation whereas caspase 3 promotes apoptosis.

Co-expression of hepatocyte growth factor and c-met in epithelial odontogenic tumors.

Hepatocyte growth factor (HGF) and its receptor, c-met, have been shown to regulate cell proliferation, motility and morphology in a variety of cell types. A significant role of the HGF/c-met pathway has been demonstrated in various tumors, however, little is known about the role of HGF/c-met pathway in odontogenic tumors. The aim of this study was to characterize the expression of HGF and c-met in 30 ameloblastomas, 7 unicystic ameloblastomas (luminal type), 10 calcifying cystic odontogenic tumors, 10 adenomatoid odontogenic tumors (AOTs), 30 keratocytic odontogenic tumors (KCOTs) and 6 ameloblastic carcinomas using an immunohistochemical method. HGF and c-met were generally immunolocalized in the cytoplasm of all epithelial tumor cells, except for keratinizing cells in acanthomatous ameloblastoma, in all the examined odontogenic tumors. These results, together with the expression of these two proteins in the epithelium of tooth germs, suggest that the HGF/c-met pathway is involved in the differentiation of odontogenic tumors. This pathway may also promote tumor proliferation in odontogenic tumors due to its potent mitogenic effect. The consistent and strong immunolocalization of HGF and c-met in squamous cells present in acanthomatous ameloblastomas, AOTs and ameloblastic carcinomas, and in the linings of KCOTs suggests that the HGF/c-met interaction may have an influence on squamous differentiation in these odontogenic tumors.

Overexpression of cdk4 and p16 in oral lichen planus supports the concept of premalignancy.

BACKGROUND: Cell cycle arrest and increased cell proliferation have been demonstrated in oral lichen planus (OLP). This study evaluated the expression of cdk4, cdk6 and p16, important proteins in the G1 phase, in OLP and compared the expression of these proteins of OLP with those of normal mucosa. METHODS: Expression of cdk4, cdk6 and p16 were investigated in 23 OLP and 10 normal mucosae using immunohistochemistry technique. Positive cells were counted and presented as a percentage of positive cells. RESULTS: Expression of cdk4, cdk6 and p16 was observed in 3/10 (30%), 1/10 (10%) and none of normal mucosa, respectively. Expression of cdk4, cdk6 and p16 was detected in 18/23 (78.3%), 8/23 (34.8%) and 15/23 (65.2%), of OLP, respectively. The numbers of cdk4 and p16 positive cases of OLP were significantly higher than normal mucosa. In normal mucosa, the averages of the percentage of positive cells for cdk4 and cdk6 staining were 1.48 and 0.18, respectively. In OLP, the averages of the percentage of positive cells for cdk4, cdk6 and p16 staining were 2.73, 1.06 and 2.24, respectively. The percentage of cdk4-positive cells of OLP was significantly higher than those of normal mucosa group. CONCLUSION: Oral lichen planus demonstrated overexpression of cdk4 and p16, but not cdk6, suggesting that epithelial cells in OLP are in the hyperproliferative state and in cell arrest. Altered expression of cdk4 and p16 provides evidence of the malignant potential in OLP.

Alteration in the expression of cdk4 and cdk6 proteins in oral cancer and premalignant lesions.

BACKGROUND: Cdk4 and cdk6, key players in G1 phase, have been shown to play an important role in the development of oral squamous cell carcinoma (OSCC). This study investigated the expression of these two proteins in OSCC and premalignant lesions including oral leukoplakia (OL) with and without dysplasia and determined if alterations in the expression of these two proteins could be used as markers of malignant transformation. METHODS: Expressions of cdk4 and cdk6 were evaluated in 61 samples including OSCC, OL with and without dysplasia and normal oral mucosa using immunohistochemistry method. Nuclear staining of the keratinocytes was considered positive and the percentage of positive cells was calculated. RESULTS: Expression of cdk4 was found in 11/15 (73.33%) OSCC, 13/14 (92.85%) OL with dysplasia, 13/20 (65%) OL without dysplasia and 3/12 (25%) normal mucosa. Expression of cdk6 was detected in 9/15 (60%) OSCC, 3/14 (21.43%) OL with dysplasia, 5/20 (25%) OL without dysplasia and 1/12 (8.33%) normal mucosa. In cdk4 stained specimens, the frequency of positive cases and the percentage of positive cells in normal mucosa was significantly lower than OL with dysplasia and OSCC. For cdk6 staining, the prevalence of positive cases and the percentage of positive cells in normal mucosa were significantly lower than OSCC. CONCLUSIONS: Overexpressions of cdk4 and cdk6 were observed in OSCC, indicating that these two proteins play a crucial role in OSCC. The aberrant expression of cdk4 was found in OL with dysplasia, suggesting that cdk4 may be involved in the early event of carcinogenesis.

Immuno-histochemical expression of p53 protein and iNOS in odontogenic cysts.

OBJECTIVE: The present study investigated the expression of p53 protein and iNOS in odontogenic keratocysts (OKCs), dentigerous cysts (DCs) and radicular cysts (RCs) and determined the correlation of these 2 proteins within each cyst type. MATERIAL AND METHOD: p53 and iNOS in epithelial lining cells were analyzed in 20 OKCs, 20 DCs and 20 RCs using immuno-histochemistry. The percentage of positive cells was assessed and presented as mean +/-SD. The correlation between the expressions of these 2 proteins in each cyst was carried out using Spearman correlation analysis. RESULTS: p53 was found in 95% of OKCs, 50% of DCs and 65% of RCs. p53-positive cells in OKCs (12.2 +/- 8.8%) were significantly higher than those in DCs (1.4 +/- 3.2%) and RCs (1.3 +/- 2.4%). iNOS was found in all examined lesions. Statistically, iNOS-positive cells in RCs (86.9 +/- 9.9%) were lower than those in OKCs (94.8 +/- 3.5%) and DCs (96.1 +/- 4.4%). No correlation between the expression of p53 and iNOS was found in each cyst. CONCLUSION: p53 was over expressed in OKCs compared with other lesions. RCs showed the lowest expression of iNOS.

Expression of p16 in oral cancer and premalignant lesions.

BACKGROUND: Expression of p16 has been proposed as a marker for malignant transformation. This study aimed to evaluate p16 expression in oral squamous cell carcinoma (OSCC) and premalignant lesions including oral leukoplakia (OL) with and without dysplasia. METHODS: Expression of p16 was investigated in 56 samples including OSCC, OL with and without dysplasia, and normal oral mucosa. Expression of p16 was identified by immunohistochemistry, using the CINtecTM p16INK4a Histology Kit. Both nuclear and/or cytoplasmic staining of the keratinocytes were considered to be positive and the percentage of positive cells was calculated. RESULTS: Expression of p16 was detected in 3/16 (18.75%) cases of OSCC, in 4/15 (26.7%) cases of OL without dysplasia, and in none of OL with dysplasia and normal mucosa. No significant differences in p16 expression prevalence were found among OSCC, OL with and without dysplasia and normal mucosa. The percentages of positive cells in OSCC and OL without dysplasia were 0.89 and 0.17, respectively. No significant difference in the percentage of positive keratinocytes was found. CONCLUSION: As a marker, p16 is not reliable for oral mucosal dysplasia and malignant transformation.

A clinicopathologic study of oral leukoplakia and erythroplakia in a Thai population.

OBJECTIVES: To determine the prevalence of oral leukoplakia and erythroplakia in a group of Thai patients and to study the clinical and pathologic features of these 2 lesions. METHOD AND MATERIALS: Cases having provisional diagnoses of leukoplakia and erythroplakia between 1973 and 2004 were retrieved from the files of the Department of Oral Pathology, Faculty of Dentistry, Mahidol University. Clinical and pathologic features were reviewed and analyzed. RESULTS: Of 7,177 biopsy specimens, 123 cases (1.7%) of leukoplakia and 9 cases (0.13%) of erythroplakia were found. There was no significant gender predilection in leukoplakia (male:female = 1.2:1). The peak of age-frequency distribution of leukoplakia was in the fourth decade among men and fifth decade among women. The most common site of leukoplakia was buccal mucosa (28.5%), followed by alveolar mucosa (18.7%) and tongue (16.3%). Microscopic study of leukoplakia revealed hyperkeratosis with or without acanthosis in 60.9% of cases, epithelial dysplasia in 10.6%, and squamous cell carcinoma in 4.9%. Erythroplakia was found in 6 men and 3 women. It was most frequently seen during the seventh decade of life. The palate was the most common site. Epithelial dysplasia and squamous cell carcinoma were found in 6 patients with erythroplakia (66.7%). CONCLUSIONS: Leukoplakia occurred 13 times more frequently than erythroplakia. However, squamous cell carcinoma was more frequently found in erythroplakia cases. Both lesions were found most frequently in elderly individuals and affected men more than women.

Calcifying epithelial odontogenic tumor: an immunohistochemical case study.

Calcifying epithelial odontogenic tumor (CEOT) is a rare benign odontogenic tumor. A case of CEOT in a 25-year-old female is presented here. Histologically, the case showed sheets of polyhedral epithelial cells with deep eosinophilic cytoplasm and prominent nuclei. Nuclear pleomorphism and hyperchromatism were evident. Globules of amyloid-like material among the tumor cells were prominent. Also found was a small area demonstrating a cribriform pattern. Immunohistochemical studies with antibodies against basement membrane proteins (laminins 1 and 5, collagen type IV and fibronectin), pan-cytokeratins AE1/AE3, vimentin, S-100 protein and CD 1a were performed. Tumor cells expressed laminins 1 and 5, fibronectin, cytokeratins and vimentin. The amyloid-like material was not reactive to all antibodies examined. A number of dendritic cells among sheets of tumor cells were revealed with strong staining for S-100 protein and CD 1a. These dendritic cells are likely to be Langerhans cells. Hence, immunohistochemistry is a useful method to study the variant of CEOT.

Expression of basement membrane components in odontogenic tumors.

OBJECTIVE: The objective was to characterize the expression of BMCs (laminins 1 and 5, collagen type IV, and fibronectin) in ameloblastomas, calcifying cystic odontogenic tumors (CCOTs), and adenomatoid odontogenic tumors (AOTs). STUDY DESIGN: BMCs were analyzed in 14 ameloblastomas, 7 CCOTs, and 7 AOTs using immunohistochemistry. RESULTS: In normal oral mucosa, linear deposits of these proteins were found at the epithelial-mesenchymal junction, but not in epithelial cytoplasm. In all tumors studied, linear deposits of all proteins were found at the epithelial-mesenchymal junction; laminin 1 was expressed in all tumor cells, regardless of cell types. For CCOTs, laminin 5 was found faintly in suprabasal cells, but expressed strongly in ghost cells. For AOTs, laminin 5 strongly decorated tumor cells adjacent to mineralization. CONCLUSIONS: Laminin 1 may be a marker for odontogenic epithelium. Additionally, laminin 5 may be involved in ghost cell formation and initiation of calcification.

A retrospective study of 60 cases of salivary gland tumors in a Thai population.

Sixty cases of salivary gland tumors were diagnosed in the Oral Pathology Department, Faculty of Dentistry, Mahidol University, Bangkok, Thailand, from 1973 to 2002. Fifty-two cases (86.7%) involved the intraoral minor salivary glands, six cases (10%) were found in the major glands, and two cases (3.3%) were intrabony. The predominance of malignant over benign tumors was evident with 68.3% being malignant and 31.7% benign. Patients ranged in age from 9 to 75 years. The female to male ratio of benign intraoral salivary gland tumors was 1.4 to 1 and of malignant types was 1.1 to 1. The principle site of occurrence was the palate (65.4%), followed by buccal mucosa (13.5%). Pleomorphic adenoma (30%) was the most common benign tumor, and mucoepidermoid carcinoma (44.3%) was the most common malignant tumor. Comparing the data from the present study with other series, some discrepancies exist.