Immunohistochemical analysis of cell cycle-associated proteins p16, pRb, p53, p27 and Ki-67 in oral cancer and precancer with special reference to verrucous carcinomas

Alterations in cell proliferative activity are a common phenomenon in oral carcinogenesis. In this study, the expression of the cell cycle-associated proteins p16, pRb, p53, p27 and Ki-67 were examined by immunohistochemistry in precancerous and cancerous oral lesions, including verrucous carcinomas (VCs). Generally, expression of pRb, p53 and Ki-67 increased according to the cell proliferative activity or tumor progression, but p27 expression showed an inverse relationship. Comparing squamous cell carcinomas (SCCs) with VCs, there was a great difference in expression levels of p27, Ki-67 and p53, which seemed to reflect the different cell proliferative activities of these two tumors. Expression of p16 was low in both dysplasia and SCCs, whereas p16 expression was high in VCs. The high immunohistochemical expression for both p16 and pRb in VC is quite different compared with SCC, which may indicate a possible relationship between VC and human papillomavirus (HPV) infection.     

Prognostic role of p21WAF1 expression in areca quid chewing and smoking-associated oral squamous cell carcinoma in Taiwan.

BACKGROUND: Alterations in p21WAF1 protein expression have been observed in a wide variety of human cancers by immunohistochemistry, and both decreased and increased levels of p21WAF1 protein expression have been shown to correlate with poor prognosis. METHOD: To examine the relation between p21WAF1 protein expression and prognosis in oral squamous cell carcinomas (SCCs), we performed an immunohistochemical study with antip21WAF1 antibody on 43 oral SCCs. Immunostaining results were then correlated with p53 protein levels, clinicopathological parameters of the tumors and overall patient survival. RESULTS: Of the 43 patients, 31 (72%) had tumors with positive p21WAF1 nuclear staining and 27 (63%) had tumors with p53 nuclear staining. There was no significant correlation between p21WAF1 and p53 protein expressions and both mutant p53-containing oral SCCs overexpressed p21WAF1 protein. In addition, no significant correlation was found between the p21WAF1 expression and the patients' age, sex, oral habit, cancer location, or primary tumor TNM status at the time of initial presentation. The Kaplan-Meier analysis showed a significant correlation between p21WAF1 protein overexpression and poor patient overall survival (P = 0.049). When p53 and p21WAF1 were evaluated together, the 5-year overall survival was lowest in p53(+)-p21WAF1(+) patients and highest in p53(-)-p21WAF1(-) patients (P = 0.057). CONCLUSION: Combined evaluation of p21WAF1 and p53 expressions may be useful in estimating the prognosis of patients with oral SCCs in Taiwan.     

Expression of p53 protein correlates with decreased survival in patients with areca quid chewing and smoking-associated oral squamous cell carcinomas in Taiwan

Expression of p53 protein was examined in oral squamous cell carcinoma (SCC) from patients who were areca quid (AQ) chewers and/or tobacco smokers, using anti-p53 antibodies with an immunoperoxidase technique. Positive p53 stain was observed in 47 of 81 (58%) cases of oral SCC. p53 overexpression was found to higher in patients without AQ chewing and smoking habits than in patients with these two habits (80% vs 52%, P=0.076). No significant correlation was found between p53 expression and the patients' age, sex, cancer location, clinical staging, primary tumor TNM status, or histological differentiation of SCC. The Kaplan-Meier analysis showed that the prognosis for patients with p53-negative tumors was significantly better than that for patients with p53-positive tumors (P<0.05). A significant correlation was also observed between positive lymph node status and poor prognosis (P<0.05). These results suggest that p53 may serve as an adjuvant marker of poor survival in patients with oral SCCs in Taiwan.     

Combined cytoplasmic and membranous EGFR and p53 overexpression is a poor prognostic marker in early stage oral squamous cell carcinoma

J Oral Pathol Med (2012) 41 : 559–567 Objective: Our aim was to evaluate the expression of several molecules that regulate growth, the cell cycle and signalling pathways including EGFR, p53, p16 and p27 in oral squamous cell carcinomas (OSCC). We examined their utility as prognostic markers by relating to clinicopathological characteristics and the clinical outcome. Patients and methods: Using tissue microarray technology, we analysed 67 primary OSCC and examined immunohistochemical expression of EGFR, p53, p16 and p27. Multivariate analysis was conducted to examine their role in survival. Results: Many of the markers were highly expressed in these cancers. Membranous EGFR expression in 95.2%, both membrane and cytoplasm expression in 35%, p53 expression in 61.6%, p27 expression in 89.5% and p16 expression in 27.9% of cases. In the multivariate analysis, independent prognostic influence of a lower overall survival was determined only for advanced tumour stage (P < 0.001), p53 overexpression (P = 0.004), EGFR cytoplasm and membrane co‐expression location (P = 0.002) and p16 reduced expression (P = 0.002). When considering a subgroup of early stage tumours, p53 overexpression (P = 0.028) and combined membranous and cytoplasm EGFR co‐expression (P = 0.039) were indicators of a lower overall survival. For disease‐free survival, in addition to these three factors, the histological grade (P = 0.011) showed independent prognostic values. Conclusion: The independent value of EGFR subcellular location (cytoplasm and membrane) and p53 overexpression in overall survival even in early stages of OSCC suggests that these markers may serve as reliable biological markers to identify high‐risk subgroups and to guide therapy.     

p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP

Trivedy C, Warnakulasuriya KAAS, Tavassoli M, Steingrimsdottir H, Penhallow J, Maher R, Johnson NW: p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP. J Oral Pathol Med 1998; 27: 72–7. © Munksgaard, 1998.
An archival series of oral biopsies from Karachi, Pakistan, consisting of 21 cases of oral submucous fibrosis (OSF) and 27 cases of squamous cell carcinoma (SCC), of which 6 had arisen from OSF, were used to examine the aberrations in the structure and expression of the p53 tumour suppressor gene. The PCR-SSCP method was used for mutation analysis of exons 2–9, and (over)expression of p53 protein was detected by immunocytochemistry using monoclonal antibody DO 7. Positive immunostaining was observed in 15/20 (75%) of OSF specimens, 3/6 (50%) of SCC arising from OSF and 14/21 (67%) of SCC not arising from OSF. Mobility shifts in SSCP indicative of a mutation in p53 or loss of heterozygosity (deletion of a band) were seen in 13/21 cases of OSF and 15/27 cases of SCC. There was concordance between immunocytochemistry and SSCP results in a majority (33/48) of samples. Though the number of analysed SCC cases arising from OSF was limited, the results suggest that p53 mutation/protein stabilisation may play a part in the pathogenesis of OSF and its progression to SCC.     

Infrequent p53 mutations in patients with areca quid chewing-associated oral squamous cell carcinomas in Taiwan

Mutations in the conserved regions (exons 5-9) of the p53 gene were investigated in 37 untreated human primary oral squamous cell carcinomas (SCCs) using polymerase chain reaction-single strand conformation polymorphism and DNA sequencing analyses. P53 mutations were detected in 2 of 37 (5.4%) oral SCC cases. One tumor sample (case 23) showed a mis-sense point mutation at codon 177, changing CCC to CTC, which resulted in a substitution of proline to leucine in the p53 protein. The other tumor (case 33) had a point mutation at codon 266, changing GGA to AGA and causing a substitution of glycine to arginine in the p53 protein. These two patients with p53 mutations did not have an areca quid chewing habit. These results suggest that mutations in the p53 gene may not play a role in the pathogenesis of human oral SCCs in Taiwan. Recently, we have shown that positive p53 staining was observed in 47 of 81 (58%) cases of oral SCC. The discrepancies between positive p53 protein staining and the low prevalence of p53 mutation in oral SCCs indicate that other mechanism(s) are involved in p53 overexpression.     

Elevated ras p21 expression in oral premalignant lesions and squamous cell carcinomas in Taiwan

Expression of ras p21 oncoproteins was examined in histological sections of oral squamous cell carcinoma (SCC), epithelial dysplasia, epithelial hyperkeratosis and normal oral mucosa using antibodies to ras p21 with an immunoperoxidase technique. Ras p21-positive staining was found in 47 of 51 (92.2%) cases of oral SCC, 4 of 4 (100%) cases of epithelial dysplasia, 7 of 7 (100%) cases of epithelial hyperkeratosis, and 1 of 6 (16.7%) cases of normal oral mucosa. The positive staining rate of ras p21 in oral SCC, epithelial dysplasia or epithelial hyperkeratosis was significantly higher than that in normal oral mucosa (P<0.05). No correlation was found between ras p21 expression and patient age, tumour location, tumour size, clinical staging or histological differentiation of SCC. However, a significant positive correlation was found between ras p21 expression and patients' sex (P<0.05) or regional lymph node status (P<0.05). A significant positive correlation was also discovered between ras p21 expression and patients' smoking habits (P<0.01), as well as daily or total betel quid (BQ) consumption (P<0.05). Of the 47 immunostain-positive SCC patients, specimens from 6 patients were also obtained after chemotherapy, when ras p21 expression was found to be reduced. These results indicate that ras p21 over expression may play an important role in the initiation and progression of oral SCCs in patients who are smokers and BQ chewers.     

Minichromosome maintenance 2 expression is correlated with mode of invasion and prognosis in oral squamous cell carcinomas

BACKGROUND: This study examined the immunohistochemical expression of cell-cycle related molecules as well as cell proliferation and pathologic findings in oral squamous cell carcinoma (SCC) in order to clarify their pathobiologic and prognostic significance. METHODS: A total of 46 oral SCC specimens were analyzed using Ki-67, minichromosome maintenance 2 (MCM2), p53, p27, p21, and TUNEL. Aspects including tumor differentiation, mode of carcinoma invasion, tumor metastasis, and patient prognosis were compared among the specimens. RESULTS: A significantly higher MCM2 labeling index (LI) was observed in the moderately differentiated SCCs when compared to the well-differentiated SCCs (P<0.05). The higher MCM2 LI was correlated with mode of invasion Grade 4 (infiltrative growth) and patient prognosis. In contrast, the LIs of Ki-67, TUNEL-signal, p53, p27, and p21 were not correlated with patient prognosis. CONCLUSION: Higher MCM2 LI provides useful information for patient prognosis in oral SCCs.     

口腔鳞状细胞癌和癌前病变中细胞周期相关蛋白p27表达的研究

目的研究口腔黏膜癌前病变和口腔鳞状细胞癌（OSCC）中细胞周期相关蛋白p27的表达。方法采用免疫组织化学方法，研究p27、p53、MDM2（murine double minute）和p21蛋白在正常口腔黏膜、口腔白斑、红斑及OSCC共115例中的表达情况，探讨其表达水平的改变与Ki-67及相关临床病理指标的关系。结果p27蛋白在癌前病变和OSCC组中的阳性率分别为79．55％和81．25％。OSCC组p27蛋白表达强阳性率为70．83％（34／48），显著高于癌前病变组的31．82％（14／44）（P〈0．001）。p27蛋白高表达组其平均Ki-67阳性细胞百分率显著高于p27蛋白低表达组（P〈0．001）。OSCC组中，p27蛋白表达强度与p53和（或）MDM2的状态相关（P=0．034）。结论细胞周期调控分子p27、p53、MDM2和p21蛋白功能异常是口腔黏膜上皮发生癌变的重要因素之一。在口腔黏膜癌前病变和OSCC中普遍存在着上述一种或多种周期调控分子的异常，且不同调控分子之间也存在着互相调节、互相制约的关系。     

p53, mdm2, and p21 expression in oral squamous cell carcinomas: relationship with clinicopathologic factors

OBJECTIVE: The purpose of this study was to clarify the correlation of expression of cell cycle-associated gene proteins with clinicopathologic factors in oral squamous cell carcinoma (SCC). STUDY DESIGN: Formalin-fixed paraffin-embedded tissues from 69 oral SCC cases and 10 normal mucosa cases were stained by immunohistochemistry (IHC) for p53, mdm 2, and p21 proteins. RESULTS: We found p53, mdm 2, and p21 expression in 44 of 69 (63.8%), 25 of 69 (36.2%), and 37 of 69 (53.6%) oral SCCs, respectively. Ki-67-labeling index of combined p53(+)/mdm 2(+) expression cases was significantly higher than those that lacked combined expression (P =.004). Combined p53(+)/p21(+) expression showed a significant association with lymph node metastasis (P =.019). In survival analysis, combined p53(+)/p21(+) and p53(+)/mdm 2(+)/p21(+) expression was associated with poor clinical outcome (P =.018 and.012, respectively). CONCLUSION: Combined p53/mdm 2 expression was associated with tumor proliferation in oral SCC. Combined p53/p21 and p53/mdm 2/p21 expression may be a predictive factor in lymph node metastasis.     

1,25(OH)2Vitamin D3 induces elevated expression of the cell cycle inhibitor p18 in a squamous cell carcinoma cell line of the head and neck

BACKGROUND: 1Alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2) Vitamin D(3)] induces growth inhibition in squamous cell carcinoma (SCC) cell lines of the head and neck by arresting the cells in the G0/G1 phase of the cell cycle, probably due to an enhanced expression of p21, which could be demonstrated in other cell lines (JPPA, SCC9) before. In SCC25, a SCC cell line isolated from tongue, growth inhibition but no overexpression of p21 was detected. The retinoblastoma gene, as a direct target of G1 cyclin-CDK complexes, showed an obvious shift from the hyperphosphorylated to the hypophosphorylated form under 1,25(OH)(2)Vitamin D(3), which indicates that the growth inhibition takes place in the G0/G1 phase. To explore the possible pathway of growth inhibition in SCC25 we investigated other cell cycle inhibitors (p18, p19, p27). METHODS: Synchronized cells were treated with 1,25(OH)(2)Vitamin D(3) over 96 h. The cell cycle status and expression of cell cycle-regulating proteins was determined by fluorescence-activated cell sorting (FACS) and Western blotting. An overexpression of p18 in 1,25(OH)(2)Vitamin D(3) vs. ethanol-treated cells was determined until 30 h in SCC25. No influence was detectable on the expression of p27 and p19. CONCLUSION: One mechanism by which 1,25(OH)(2)Vitamin D(3) controls cell growth might be the upregulation of p21. As p21 was unsusceptible to 1,25(OH)(2)Vitamin D(3) in SCC25, other inhibiting proteins were necessary to be tested. The proven upregulation of p18 seems to be the responsible step for growth inhibition of 1,25(OH)(2)Vitamin D(3) in SCC25.     

MDM2 expression in areca quid chewing-associated oral squamous cell carcinomas in Taiwan

MDM2 (murine double minute gene 2) overexpression has been implicated in the pathogenesis of human tumors via inhibition of the p53 tumor suppressor protein. To investigate the potential involvement of MDM2 overexpression in the pathogenesis of oral squamous cell carcinomas (SCCs) in Taiwan, we examined the expression of MDM2 protein and its relationship to p53 protein levels in 52 oral SCCs using antibodies to MDM2 and p53. Of the 52 patients, 36 (69 %) had tumors with positive MDM2 nuclear staining and 32 (61%) had tumors with p53 nuclear staining. Co-expression of MDM2 protein and p53 was detected in 25 (48%) cases; and 9 (17%) tumors showed neither MDM2 protein nor p53 staining. A significant correlation was observed between MDM2 protein and p53 expression in 38 cases with an areca quid (AQ) chewing habit (P=0.032). No significant correlation was found between the degree of MDM2 protein staining and the patients' ages, sex, cancer location, clinical staging, primary tumor TNM status or histological differentiation of SCC at the time of initial presentation. Kaplan-Meier analysis showed that either MDM2 protein expression or co-expression of p53 and MDM2 protein did not relate significantly to patient overall survival. Nevertheless, the high prevalence of MDM2 protein overexpression found in this study suggest that MDM2 may also participate in the carcinogenesis of AQ chewing-associated oral SCCs in Taiwan.     

Alterations of tumor suppressor genes and the H-ras oncogene in oral squamous cell carcinoma

The frequencies of mutations in the adenomatous polyposis coli (APC). p53, and p16 (MTS1: multiple tumor suppressor 1/CDK4I: cyclin-dependent kinase 4 inhibitor) tumor suppressor genes were investigated in 23 oral squamous cell carcinomas (SCCs). Loss of heterozygosity (LOH) at the retinoblastoma (Rb) gene locus and on chromosomes 3p (VHL; von Hippel-Lindau disease tumor suppressor gene locus). 5q (APC) and 9p (p16). and H- ras oncogene mutations were also studied in the same samples. Techniques employed were polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP), DNA sequencing and PCR-microsatellite analyses. Mutations of the p53 gene were detected in 26% (6/23) of the tumor specimens. APC and p!6 were not mutated in any of the 23 oral SCCs studied. LOH was detected in 17% (2/12 informative cases) at the Rb, in 33% (4/12) on 3p, in 17% (4/23) on 5q and in 30% (3/10) on 9p. Mutations of the H- ras gene were detected in 9% (2/23). The only correlation between these genetic alterations and clinicopathologic characteristics was that mutations of the p53 gene were detected more frequently in oral SCCs with lymph node metastasis than in those without it ( P <0.05). These results demonstrate that mutations of the p53 gene and LOH on 3p and 9p frequently occur in oral SCC and play important roles in the development and/or progression of this common malignancy.     

P53 and MDM2 co-expression in tobacco and betel chewing-associated oral squamous cell carcinomas

Oral cancers of tobacco and betel chewers represents a unique in-vivo model to understand the genotoxic effect of tobacco and betel carcinogens on oncogenes and tumor suppressor genes. Coordinated interactions of p53 and MDM2 play an important role in regulation of critical growth control gene following exposure to DNA damaging agents. The purpose of this study is to determine if the tumor suppressor function of p53 is inactivated by mutation or other alternative mechanisms in carcinogen-induced oral squamous cell carcinoma (SCC), and to investigate the clinicopathological significance of p53 and MDM2 expression. The p53 mutation in oral SCC of tobacco and betel chewers (n=40) was detected by polymerase chain reaction - single strand conformation polymorphism (PCR-SSCP) analysis and immunohistochemistry (IHC) was done to investigate p53 and MDM2 proteins overexpression. The incidence of p53 mutation was relatively low (17.5%), but there was a high prevalence of MDM2 overexpression (72.5%). In the total of 40 cases, IHC phenotype showed p53 positive immunostaining with MDM2 positive immunostaining (p53+/MDM2+) 62.5%, p53 negative immunostaining with MDM2 negative immunostaining (p53-/MDM2-) 15%, p53 positive immunostaining with MDM2 negative immunostaining (p53+/MDM2-) 12.5%, and p53 negative immunostaining with MDM2 positive immunostaining (p53-/MDM2+) 10%. A significant correlation was found between MDM2 and p53 overexpression (p=0.0289). Moreover, p53+/MDM2+ phenotype was significantly associated with poorly differentiated tumors (p= 0.0007). These results conclude that other factors than p53 mutation is likely to be the targets of tobacco/betel carcinogens and MDM2 may play an important role in tobacco/betel chewing-related oral SCCs. Overexpression of MDM2 protein may constitute an alternative mechanism for p53 inactivation.     

The chemoadjuvant potential of grape seed procyanidins on p53-related cell death in oral cancer cells

J Oral Pathol Med (2012) 41 : 322–331 Background: To clarify the efficacy of grape seed procyanidin (GSP) on antiproliferative effects related to p53 functional status of oral squamous cell carcinoma (OSCC) for its chemoadjuvant potential. Methods: We used GSP to investigate SCC‐25 cells with wild‐type p53 gene and OEC‐M1 cells with mutant p53 gene for the assessment of antiproliferative effects including cell viability, cell cycle, apoptosis, migration and invasion potential, and alterations of associated oncoproteins involved in cellular and molecular events. Results: The findings suggest that GSP on OEC‐M1 cells leads to cell cycle arrest by increasing the expression of p21^Cip1/p27^Kip1 protein without functioning mitochondria‐mediated apoptosis, whereas GSP on SCC‐25 cells inhibits cell proliferation via both G1‐phase arrest and mitochondria‐mediated apoptosis in a dose‐dependent manner as a result of alterations of Bcl‐2. GSP also inhibits the migration and invasion of both cells, which are associated with the suppression of matrix metalloproteinases (MMPs), MMP‐2 and MMP‐9. Conclusion: Antiproliferative effectiveness of GSP is closely associated with the p53 status of OSCC cells. GSP displays chemoadjuvant potential via cell cycle blockage and apoptotic induction. Our findings clearly suggest that GSP may play a role as a novel chemopreventive or therapeutic agent for OSCC.     

p53 overexpression in head and neck squamous cell carcinoma: Review of the literature

As a tumour suppressor gene, the inactivation of p53 induces the development of numerous human cancers. Mutations of p53 have been implicated in the pathogenesis of head and neck squamous cell carcinoma (HN-SCC) at a high incidence. In premalignant lesions and in situ carcinomas, p53 overexpression is not exclusively restricted to neoplastic cells, but frequently affects the normal appearing keratinocytes adjacent to p53 positive neoplasms or present in dysplastic areas. These results suggest that as contributors to the early phases of HN-SCC development, p53 alterations may be excellent biomarkers that indicate the predisposition of a particular oral cavity premalignant lesion toward malignancy. In most cases, the p53 overexpression status of a tumour metastasis is identical to that of a primary tumour, indicating that a p53 mutation precedes metastatic spread. In patients with multiple primary tumours, multiple foci of p53 overexpression are observed in epithelia distant from the tumour. So the expression of p53 in normal epithelium would indicate an increased risk for transformation to second or third primary cancers. Distinct p53 mutations in different primary tumours of the same patient indicate that these cancers arise as independent events; these results support the existence of multifocal polyclonal processes. Regardless of the aforementioned results that support p53 as a valid tumour biomarker, most studies have shown no relationship between the expression of p53 and clinical and histopathological parameters. The role played by p53 mutations in the progression and vital prognosis of HN-SCC has not yet been demonstrated.     

p53-p21waf1通路在口腔鳞状细胞癌中心体扩增中的作用及意义

目的 了解口腔鳞状细胞癌(oral squamous cell cancer,OSCC)p21waf1蛋白表达与中心体扩增的相关性,探讨p53-p21waf1通路在OSCC中心体扩增中的作用及意义.方法 8例正常口腔黏膜及27例OSCC石蜡包埋组织,采用间接免疫荧光双重染色法了解OSCC组织中心体扩增情况;采用流式细胞术及免疫组织化学方法对相应组织p21waf1蛋白表达量及突变型p53蛋白进行检测,分析三者间的相关性.结果 中心体数目扩增(＞2个/细胞)可见于78%(21/27)的OSCC组织,p21waf1蛋白表达量在有中心体扩增的OSCC组织中[(0.878±0.081)]低于无中心体扩增的OSCC组织[(0.952±0.018),t=3.838,P=0.001],OSCC组织中心体扩增程度与p21waf1蛋白表达量间存在负相关关系(r=0.472,P＜0.05);p21waf1蛋白表达量在OSCC组织p53阳性组[(0.823±0.071)]低于p53阴性组[(0.909±0.075),t=3.905,P＜0.01],两者间存在负相关关系(r=-0.491,P＜0.05).结论 p53-p21waf1通路可能参与了OSCC中心体循环调控,p53突变导致的p21waf1蛋白表达下调在OSCC中心体扩增中可能起一定作用.     

Immunohistochemical distribution and morphometric analysis of aquaporin-3 in oral squamous cell carcinoma

This study aimed to evaluate the relationship of aquaporin-3 (AQP3) expression with clinico-pathological parameters and lymph node metastasis in patients with oral squamous cell carcinoma (SCC). The immunohistochemical distribution of AQP3 was investigated in normal squamous epithelium and SCC tissue of 48 cases of SCC of the tongue and floor of the mouth. The percentage of the total AQP3-positive SCC tissue area relative to the total tumour tissue area (T-AQP3) was calculated as a morphometric AQP3 parameter for each patient. Furthermore, the percentage of the AQP3-positive area relative to the SCC tissue area at the invasion front (F-AQP3) was calculated as another AQP3 parameter. The immunostaining pattern of AQP3 in SCC tissue was irregular and weaker than that in normal epithelium. Well-differentiated SCCs had higher T-AQP3 and F-AQP3 values than poorly differentiated SCCs. SCCs with an infiltrative invasion pattern had lower F-AQP3 than SCCs with expansive and intermediate patterns. SCCs with T-AQP3 <27% or F-AQP3 <17% showed an increased incidence of lymphatic metastasis, and multivariate analysis demonstrated that F-AQP3 was an independent prognostic factor of lymphatic metastasis. These results suggest that AQP3 is involved in keratinocyte differentiation and decreased AQP3 expression is associated with more aggressive tumour behaviour.     

Keratin 19 downregulation by oral squamous cell carcinoma lines increases invasive potential.

Squamous cell carcinoma (SCC) of the head and neck is the sixth most frequent cancer worldwide. The survival rate is among the lowest of the major cancers and has not improved significantly in the past two decades. Extensive local invasion and regional lymph node metastasis are, in large part, responsible for the poor clinical outcome of these tumors. Keratin intermediate filaments are the most abundant cytoskeletal proteins in SCCs and regulate the migration of normal and transformed epithelial cells. Previous studies have shown that expression of the 40-kDa keratin K19 is dysregulated in SCCs arising from oral epithelium. Immunohistochemical experiments demonstrated that, while normal epithelium and dysplastic lesions expressed abundant K19 protein, invasive SCCs exhibited a patchy or negative staining pattern. We subsequently determined that K19 expression was consistently downregulated in seven SCC lines compared with normal epithelium. We therefore wanted to determine if K19 downregulation affected the invasive phenotype of these cells. We found that SCC lines which do not express K19 are significantly more invasive in vitro than those which retain expression of this gene. Stable expression of the K19 cDNA in K19 negative cell lines altered cell morphology and intercellular adhesiveness, and significantly decreased the number of cells able to migrate through a reconstituted basement membrane. Reduced invasiveness was not due to decreased metalloproteinase activity in the K19-expressing clones. We conclude that K19 overexpression in oral SCCs decreases their invasive potential by diminishing migratory capability.     

MTS1 gene mutations in archival oral squamous cell carcinomas

Multiple tumor suppressor gene 1 (MTS1) has been found mutated or deleted in a variety of human cancers. Our purpose was to identify and characterize MTS1 gene mutations in primary oral squamous cell carcinomas (SCCs) in each of the three exons of the MTS1 gene. Seventeen archival samples of oral SCC were evaluated for the presence of MTS1 mutations using single strand conformation polymorphism (SSCP) and DNA sequencing. Three of 17 tumors exhibited MTS1 gene mutations; one tumor exhibited a mutation in exon 2 and two tumors exhibited mutations at the splice site junction of intron 2 and exon 3. Three tumors also exhibited a common base change in the 3'untranslated region of exon 3, which is interpreted as a likely polymorphic variant. An examination of the three tumors exhibiting MTS1 point mutations revealed no unique characteristics relative to p53 immunohistochemical activity, mitotic frequency, or degree of histologic differentiation. This study indicates that MTS1 gene mutations may be involved in at least a minor proportion of oral SCCs.