Phenotypic alterations in Rb pathway have more prognostic influence than p53 pathway proteins in oral carcinoma

Unraveling the Genetic Web: H-Ras Expression and Mutation in Oral Squamous Cell Carcinoma-A Systematic Review

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a commonly occurring malignancy with complex genetic alterations contributing to its development. The H-Ras, a proto-oncogene, becomes an oncogene when mutated and has been implicated in various cancers. This systematic review aims to research to what extent H-Ras expression and mutation contribute to the development and progression of OSCC, and how does this molecular alteration impacts the clinical characteristics and prognosis in patients with OSCC.

METHODS

A thorough electronic scientific literature search was carried out in PUBMED, SCOPUS, and GOOGLE SCHOLAR databases from 2007 to 2021. The search strategy yielded 120 articles. Following aggregation and filtering all results through our inclusion and exclusion criteria total 9 articles were included in our literature review. It has also been registered with PROSPERO (CRD42023485202).

RESULTS

It was found that mutations in the Ras gene commonly reported in hotspots at codons 12, 13, and 61 resulting in the activation of downstream signaling pathways causing abnormal and uncontrolled cell growth. This systematic review has shown an increased prevalence of H-Ras mutation in well-differentiated OSCC and also the prevalence of H-Ras mutation in individuals engaging in multiple risk behaviors, particularly chewing tobacco, demonstrated a significant association with a higher prevalence of H-Ras positivity.

CONCLUSION

This review sheds light on the prevalence of H-Ras mutations, their association with clinical characteristics, and their potential implications for OSCC prognosis. It also enhances our comprehension of the molecular mechanisms that underlie OSCC and paves the way for further research into targeted treatments based on H-Ras alterations.

Oral squamous cell carcinomas: state of the field and emerging directions

Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% of oral malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases were reported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by 2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ), and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oral mucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involves genetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeutic interventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCC and OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors, thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC. Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitate comprehension and provide several prospective outlooks for the fields.

Prognostic and Clinicopathological Significance of the Loss of Expression of Retinoblastoma Protein (pRb) in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aims to evaluate the scientific evidence on the implications of retinoblastoma protein (pRb) alterations in oral cancer, in order to determine its prognostic and clinicopathological significance. PubMed, Embase, Web of Science, and Scopus were searched for studies published before February 2022, with no restrictions by publication date or language. The quality of the studies using the Quality in Prognosis Studies tool (QUIPS tool). Meta-analysis was conducted to achieve the proposed objectives, as well as heterogeneity, subgroup, meta-regression, and small study-effects analyses. Twenty studies that met the inclusion criteria (2451 patients) were systematically reviewed and meta-analyzed. Our results were significant for the association between the loss of pRb expression and a better overall survival (HR = 0.79, 95%CI = 0.64-0.98, p = 0.03), whereas no significant results were found for disease-free survival or clinico-pathological parameters (T/N status, clinical stage, histological grade). In conclusion, our evidence-based results demonstrate that loss of pRb function is a factor associated with improved survival in patients with OSCC. Research lines that should be developed in the future are highlighted.

Significant Association of Cyclin D1 Promoter Genotypes With Asthma Susceptibility in Taiwan

BACKGROUND/AIM

The molecular mechanisms underlying the association between cell cycle and asthma are poorly understood, and cyclin D1 (CCND1) is found to be upregulated in asthma airway smooth muscle. We investigated whether the most frequently examined functional variants in CCND1 determine asthma susceptibility.

MATERIALS AND METHODS

We genotyped 651 participants for single-nucleotide polymorphisms (SNPs) at rs9344 and rs678653 on CCND1 and assessed the association of these SNPs with asthma risk.

RESULTS

Significant differences were found in the distributions of genotypic (p=0.0064) and allelic (p=0.0021) frequencies of CCND1 rs9344. In addition, AG or GG carriers had 0.63- or 0.48-fold adjusted odds ratios for asthma risk (95%confidence intervals=0.48-0.92 and 0.22-0.78, respectively) than those who carried the AA wildtype.

CONCLUSION

Our results suggest that cell cycle regulation may play a role in asthma initiation and development, and the CCND1 rs9344 genotype may serve as an early detection marker for asthma.

Contribution of Matrix Metalloproteinase-1 Genotypes to Colorectal Cancer in Taiwan

BACKGROUND/AIM

Matrix metalloproteinase-1 is responsible for extracellular matrix regulation, and its genetic role in colorectal cancer (CRC) is unclear. The aim of the study was to investigate the contribution of Matrix metalloproteinase-1 genotypes to CRC risk in Taiwan.

MATERIALS AND METHODS

A total of 362 cases and 362 controls were included and their MMP-1 -1607 (rs1799705) genotypes were examined. The environmental factors and clinical-pathological records were also analyzed.

RESULTS

The genotypic frequency of MMP-1 rs1799750 were different between the CRC and control groups (p for trend=0.0083). 1G/2G and 1G/1G were associated with lower risk (p=0.0438 and 0.0030, adjusted OR=0.73 and 0.54, 95%CI=0.54-0.90 and 0.37-0.83). Among non-smokers, those with 1G/2G and 1G/1G genotypes were at 0.70- and 0.48-fold odds of having CRC. Among non-alcohol drinkers, people with 1G/2G and 1G/1G genotypes were at 0.71- and 0.54-fold odds. The 1G/1G genotype were statistically lower among CRC patients with lymph node metastasis (7.2%) than those without (19.0%).

CONCLUSION

The genotypes at MMP-1 rs1799705 play a role in determining susceptibility to CRC risk in Taiwan.

Immunohistochemical Expression of Five Protein Combinations Revealed as Prognostic Markers in Asian Oral Cancer

Oral squamous cell carcinoma (OSCC) has a high mortality rate (∼50%), and the 5-year overall survival rate is not optimal. Cyto- and histopathological examination of cancer tissues is the main strategy for diagnosis and treatment. In the present study, we aimed to uncover immunohistochemical (IHC) markers for prognosis in Asian OSCC. From the collected 742 synthetic lethal gene pairs (of various cancer types), we first filtered genes relevant to OSCC, performed 29 IHC stains at different cellular portions and combined these IHC stains into 398 distinct pairs. Next, we identified novel IHC prognostic markers in OSCC among Taiwanese population, from the single and paired IHC staining by univariate Cox regression analysis. Increased nuclear expression of RB1 [RB1(N)↑], CDH3(C)↑-STK17A(N)↑ and FLNA(C)↑-KRAS(C)↑were associated with survival, but not independent of tumor stage, where C and N denote cytoplasm and nucleus, respectively. Furthermore, multivariate Cox regression analyses revealed that CSNK1E(C)↓-SHC1(N)↓ (P = 5.9 × 10^–5; recommended for clinical use), BRCA1(N)↓-SHC1(N)↓ (P = 0.030), CSNK1E(C)↓-RB1(N)↑ (P = 0.045), [CSNK1E(C)-SHC1(N), FLNA(C)-KRAS(C)] (P = 0.000, rounded to three decimal places) and [BRCA1(N)-SHC1(N), FLNA(C)-KRAS(C)] (P = 0.020) were significant factors of poor prognosis, independent of lymph node metastasis, stage and alcohol consumption. An external dataset from The Cancer Genome Atlas HNSCC cohort confirmed that CDH3↑-STK17A↑ was a significant predictor of poor survival. Our approach identified prognostic markers with components involved in different pathways and revealed IHC marker pairs while neither single IHC was a marker, thus it improved the current state-of-the-art for identification of IHC markers.

Focus on HPV Infection and the Molecular Mechanisms of Oral Carcinogenesis

This study is focused on the epidemiological characteristics and biomolecular mechanisms that lead to the development of precancerous and cancerous conditions of oral lesions related to Human Papilloma Virus (HPV) infections. Current evidence from the literature demonstrates the role of HPV in potentially malignant oral disorders. Therefore, the underlying biomolecular processes can give arise, or contribute to, benign lesions as well as to oral carcinogenesis.

Computational analysis of Cyclin D1 gene SNPs and association with breast cancer

CCND1 encodes for Cyclin D1 protein and single-nucleotide polymorphisms (SNPs) can modulate its activity. In the present study, the impact of CCND1 SNPs on structure and/or function of Cyclin D1 protein using in silico tools was investigated. Our analysis revealed only one splice site SNP (c.1988+5G<A) can effect CCND1 function. Subsequently, 78 out of 169 missense variants were predicted as pathogenic by Polyphen2, SIFT, PROVEAN, SNPs&GO, and PANTHER, and 4/78 missense SNPs were further evaluated because these four SNPs were found to be reside in highly conserved region of Cyclin D1. However, they did not show any major impact on tertiary structure and domain of Cyclin D1 but overall R15S and A190S has displayed a significant diseased phenotype and an altered molecular mechanism predicted by MutPred, FATHMM, SNPeffect, SNAP2, and PredictSNP. Consistently, A190S, R179L, and R15S may also cause a decrease in stability of Cyclin D1 anticipated by I-Mutant, HOPE and SNP effect. Furthermore, the Kaplan–Meier plotter has explained that high expression of CCND1 is associated with less survival rate of breast cancer patients. Altogether our study suggests that c.1988+5G<A, R15S, R179L, and A190S SNPs could directly or indirectly destabilize Cyclin D1.

RNA-Binding Proteins as Regulators of Migration, Invasion and Metastasis in Oral Squamous Cell Carcinoma

Nearly 7.5% of all human protein-coding genes have been assigned to the class of RNA-binding proteins (RBPs), and over the past decade, RBPs have been increasingly recognized as important regulators of molecular and cellular homeostasis. RBPs regulate the post-transcriptional processing of their target RNAs, i.e., alternative splicing, polyadenylation, stability and turnover, localization, or translation as well as editing and chemical modification, thereby tuning gene expression programs of diverse cellular processes such as cell survival and malignant spread. Importantly, metastases are the major cause of cancer-associated deaths in general, and particularly in oral cancers, which account for 2% of the global cancer mortality. However, the roles and architecture of RBPs and RBP-controlled expression networks during the diverse steps of the metastatic cascade are only incompletely understood. In this review, we will offer a brief overview about RBPs and their general contribution to post-transcriptional regulation of gene expression. Subsequently, we will highlight selected examples of RBPs that have been shown to play a role in oral cancer cell migration, invasion, and metastasis. Last but not least, we will present targeting strategies that have been developed to interfere with the function of some of these RBPs.

Molecular biology of oral cavity squamous cell carcinoma

Oral cavity squamous cell carcinoma (OCSCC) is a heterogeneous and complex disease that arises due to dysfunction of multiple molecular signaling pathways. Recent advances in high-throughput genetic sequencing technologies coupled with innovative analytical techniques have begun to characterize the molecular determinants driving OCSCC. An understanding of the key molecular signaling networks underlying the initiation and progression of is essential for informing treatment of the disease. In this chapter, we discuss recent findings of key genes altered in OCSCC and potential treatments targeting these genes.

Identifying Mutually Exclusive Gene Sets with Prognostic Value and Novel Potential Driver Genes in Patients with Glioblastoma

The pathogenesis and prognosis of glioblastoma (GBM) remain poorly understood. Mutual exclusivity analysis can distinguish driver genes and pathways from passenger ones. The purpose of this study was to identify mutually exclusive gene sets (MEGSs) that have prognostic value and to detect novel driver genes in GBM. The genomic alteration profile and clinical information were derived from The Cancer Genome Atlas, and the MEGSA method was used to identify the MEGS. Next, we performed survival analysis and constructed a risk prediction model for prognostic stratification. Leave-one-out cross-validation and permutation test were used to evaluate its performance. Finally, we identified 21 statistically significant MEGSs. We found that the MEGS in the RB pathway was significantly associated with poor prognosis, after adjusting for age and gender (HR = 1.837, 95% CI: 1.192-2.831). Based on the risk prediction model, 208 (80.9%) and 49 (19.1%) patients were assigned to high- and low-risk groups, respectively (log-rank: p < 0.001, adjusted p=0.001). Additionally, we found that SPTA1, a novel gene involved in the MEGS, was mutually exclusive with members of cell cycle, P53, and RB pathways. In conclusion, the MEGS in the RB pathway had considerable clinical value for GBM prognostic stratification. Mutated SPTA1 may be involved in GBM development.

Molecular pathways of oral cancer that predict prognosis and survival: A systematic review

Several genes and pathways associated with oral squamous cell carcinoma (OSCC) are significant in terms of early detection and prognosis. The objective of this literature review is to evaluate the current research on molecular pathways and genes involved in oral cancer. Articles on the genes involved in oral cancer pathways were evaluated to identify potential biomarkers that can predict survival. In total, 36 articles were retrieved from internet databases, including EBSCO Host, Google Scholar, PubMed, and Science Direct, using the keywords "biomarker of oral cancer," "pathways of oral cancer," "genes involved in oral cancer," and "oral cancer pathways." A total of 36 studies related to OSCC were chosen. Most of the studies used cell lines, while others used archival tissues, few studies followed up the cases. Three major interlinked pathways found were the nuclear factor kappa B (NF-kB), PI3K-AKT, and Wnt pathways. The commonly mutated genes were cyclin D1 (CCND1), Rb, p53, FLJ10540, and TC21. The NF-kB, PI3K-AKT, and Wnt pathways are most frequently involved in the molecular pathogenesis of oral cancer. However, the CCND1, Rb, p53, FLJ10540, and TC21 genes were found to be more accurate in determining patients' overall survival. Polymerase chain reaction, immunohistochemistry, and immunoblotting were the commonly used detection methods.

Contribution of Murine Double Minute 2 Genotypes to Colorectal Cancer Risk in Taiwan

BACKGROUND/AIM

The genomic role of human mouse double minute 2 (MDM2) in colorectal cancer (CRC) is unclear, therefore, our study aimed to evaluate the contribution of MDM2 genotype to the risk of CRC in Taiwan.

MATERIALS AND METHODS

In this case-control study, MDM2 SNP309 T to G (rs2279744) genotypes were determined and their association with CRC risk were investigated among 362 patients with CRC and 362 age- and gender-matched healthy controls in central Taiwan. In addition, the interaction of MDM2 SNP309 genotypes with personal behaviors and clinicopathological features were also examined.

RESULTS

The percentage of variant GG for the MDM2 SNP309 genotype was 30.9% in the CRC group and 24.0% in the control group, respectively (odds ratio (OR)=1.78, 95% confidence interval (CI)=1.25-2.86, p=0.0057). The allelic frequency distribution analysis showed that the variant G allele of MDM2 SNP309 conferred a significantly increased susceptibility to CRC compared with the wild-type T allele (OR=1.32, 95% CI=1.14-1.69, p=0.0062). As for the gene-lifestyle interaction, there was an obvious joint effect of MDM2 SNP309 GG genotype on the risk of CRC among ever-smokers and non-alcohol drinkers, but not non-smoker or alcohol drinker subgroups. No statistically significant correlation was observed between MDM2 SNP309 genotypic distributions and age, gender, tumor size, location or metastasis status.

CONCLUSION

The genotypes of MDM2 SNP309 may allow forr early detection of and predictor for CRC risk, especially among smokers and non-alcohol drinkers, but not for prognosis. The combined effects of MDM2 SNP309 and other genes (such as matrix metalloproteinases) on CRC susceptibility and prognosis, should also be taken into consideration in the era of precision medicine.

The Contribution of MMP-7 Genotypes to Colorectal Cancer Susceptibility in Taiwan

BACKGROUND/AIM

Matrix metalloproteinases (MMPs) play important roles in inflammation and carcinogenesis, but the genotypic role of MMP-7 has never been investigated in colorectal cancer (CRC) among the Taiwanese. Therefore, in this study we aimed to evaluate the contribution of MMP-7 genotypes to the risk of CRC in Taiwan.

MATERIALS AND METHODS

In this case-control study, MMP-7 A-181G and C-153T promoter genotypes were determined and their association with CRC risk were investigated among 362 CRC patients and 362 age- and gender-matched healthy controls. In addition, the interaction of MMP-7 genotypes and personal behaviors were also examined.

RESULTS

The percentages of variant AG and GG for MMP-7 A-181G genotypes were 10.5% and 1.7% in the CRC group and 11.9% and 2.2% in the control group, respectively (p for trend=0.7145). The allelic frequency distribution analysis showed that the variant G allele of MMP-7 A-181G conferred a slight but non-significant decreased CRC susceptibility to the wild-type C allele (odds ratio (OR)=0.86, 95% confidence interval (CI)=0.64-1.31, p=0.37). Taiwanese all harbour the CC genotype at MMP-7 C-153T. As for the gene-lifestyle interaction, there were no obvious joint effects of MMP-7 A-181G genotype on the risk of CRC among ever smoker, alcohol drinker, non-smoker or non-drinker subgroups. No statistically significant correlation was observed between MMP-7 A-181G genotypic distributions and age, gender, tumor size, location or metastasis status.

CONCLUSION

The genotypes of MMP-7 A-181G may play an indirect role in determining personal susceptibility to CRC and prognosis. The further genotyping work on MMP-7 and other genes (such as other MMPs, oncogenes and tumor suppression genes) on CRC susceptibility and prognosis, should be taken into consideration spontaneously in the precision medicine era.

Tumor suppressor role of microRNA-1296 in triple-negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis, which lacks effective targeted therapies. There is an urgent need to better understand the underlying molecular mechanisms of TNBC aggressiveness and identify novel, efficient targets for therapeutic intervention.

METHODS

miRNA qRT-PCR was used to determine the expression of miR-1296 in cell lines. The miR-1296 overexpression effects in TNBC cell lines were investigated using assays of colony formation, cell cycle and apoptosis. Immunoblotting was performed to determine the expression of the miR-1296 target protein, and luciferase assays were performed to confirm the target of miR-1296 action.

RESULTS

miR-1296 expression was significantly suppressed in TNBC cell lines and tissues samples. Overexpression of miR-1296 significantly suppressed cell proliferation of two TNBC cell lines when compared to control miRNA-expressing cells. A significant decrease in the S-phase of the cell cycle was observed following miR-1296 overexpression, accompanied by induction of apoptosis in TNBC cells. Cyclin D1 (CCND1) was identified as a target of miR-1296 action. miR-1296 overexpression significantly suppressed the luciferase activity of reporter plasmid containing the 3'UTR of CCND1 and protein expression levels of CCND1 in TNBC cells. The effects of miR-1296 overexpression on TNBC cell growth were reversed by CCND1 overexpression. miR-1296 expression sensitized TNBC cells to cisplatin treatment.

CONCLUSION

Our results demonstrate a novel tumor suppressor role for miR-1296 in triple-negative breast cancer cell lines, identify CCND1 as its target of action, and demonstrate a potential role for miR-1296 in sensitizing breast cancer cells to cisplatin.

Prognostic significance of p16, p53, Bcl-2, and Bax in oral and oropharyngeal squamous cell carcinoma

Background: The proteins p16, p53, Bcl-2, and Bax are important cell cycle and apoptotic regulators involved in carcinogenesis and found to have prognostic significance in various cancers. However, the data for squamous cell carcinoma of oral cavity (OSCC) and of oropharynx (OPSCC) are conflicting.

Objective: We sought to determine if expression of p16, p53, Bcl-2, and Bax expression are associated with 5-year overall survival (OS) of patients with OSCC and OPSCC.

Methods: One-hundred thirty-seven cases of OSCC and 140 cases of OPSCC diagnosed from January 2002 to December 2004 at Songklanagrind Hospital, Songkhla, Thailand, were analyzed using a Cox proportional hazards model for 5-year OS in relation to immunohistochemical detection of Bcl-2, Bax, p53, and p16 proteins.

Results: The frequencies of p16, p53, Bcl-2, and Bax expression in OSCC were 13%, 45%, 4%, and 66%, and in OPSCC were 18%, 53%, 22%, and 75%, respectively. In univariate analysis, clinical variables including T stage, N stage and treatment were significantly associated with survival. In multivariate Cox regression, Bax overexpression was significantly associated with poor survival both in OSCC (HR 1.77, 95% CI 1.04-3.01) and in OPSCC (HR 2.21, 95% CI 1.00-4.85). We found no significant association of p16, Bcl-2, and p53 expression with survival.

Conclusion: The expression pattern of p16, p53, Bcl-2, and Bax are similar in OSCC and OPSCC. Only Bax expression has prognostic significance for both tumor sites.

Down-regulation of β-catenin and the associated migration ability by Taiwanin C in arecoline and 4-NQO-induced oral cancer cells via GSK-3β activation

Cancer is one of the leading causes of death worldwide, and oral squamous cell carcinoma (OSCC) accounts for almost a sixth of all reported cancers. Arecoline, from areca nut is known to enhance carcinogenesis in oral squamous cells. The objective of this study is to determine the effect of Taiwanin C, from Taiwania cryptomerioides Hayata against Arecoline-associated carcinogenesis. An OSCC model was created in C57BL/6J Narl mice by administrating 0.5 mg mL^-1 arecoline with 0.2 mg mL^-1 4-NQO carcinogen for 8 and 28 wk to mimic the etiology of oral cancer patients in Asia. Mice were sacrificed and two cell lines, T28 from the tumor and N28 cancerous cell line from the surrounding non tumor area, were established. Taiwanin C showed effective anti-tumor activity in nude mice models. Taiwanin C significantly inhibited the cell viability of T28 cells in a dose dependent manner, but did not inflict any effect on N28 normal cells. Taiwanin C treatment inhibited the migration ability of T28 cells in a dose dependent manner as determined by wound healing and migration assays. Taiwanin C also reduced the levels of β-catenin and its downstream metastatic proteins, Tbx3 and c-Myc. Besides, Taiwanin C inhibited the nuclear accumulation of β-catenin and induced β-catenin degradation via proteasome-mediated pathway. Moreover, Taiwanin C enhanced GSK-3β and reduced the p-ser⁹ GSK-3β protein level to inactivate Wnt signaling. Taken together, Taiwanin C blocked the cell migration effects of T28 cells mediated through the activation of GSK-3β to enhance protein degradation and reduce nuclear accumulation of β-catenin. © 2016 Wiley Periodicals, Inc.

The Loss of p16 Expression Worsens the Prognosis of OSCC

Oral squamous cell carcinoma is the most common neoplasia of the mouth. Downregulation of p16(INK4a) (a cyclin-dependent kinase inhibitor) has been reported for mouth cancer and it is believed that its inactivation is an early event in oral carcinogenesis. The goal of this article is to quantitatively report expression of p16(INK4a) and the state of methylation in oral squamous cell carcinoma, and evaluate its relationship with the clinical and prognostic factors, in addition to setting out a multivariate model that predicts survival. The mean expression of p16(INK4a) was 7.70 (SD=14.07) (F=0.894; P=0.449). According to the semiquantitative analysis, there were statistically significant differences, where 19 cases were negative (<2 %), 11 at initial stages, and 8 at advanced stages (χ(2)=6.016; P<0.05). The methylation of p16(INK4a) was not associated with any of the clinical or pathologic variables. Kaplan-Meier curve showed a better survival for patients in initial stages (40.72 mo) compared to those in advanced stages (28.6 mo) (P<0.01). Survival was also reduced in a statistically significant manner in patients with any degree of dysplasia in the adjacent margin (P<0.05). During univariate Cox regression analysis, it was observed that individuals with relapse had a higher risk (almost 9 times higher) [P<0.001; hazard ratio=8.91; 95% confidence interval (CI), 4.18-19.02]. During the Cox multivariate analysis for each unit of decrease in p16(INK4a), the risk increased by 1.06) (P<0.05; hazard ratio=0.94; 95% CI, 0.89-1.00). p16(INK4a) expression is reduced with advancing tumor stage and its gene silencing is associated with an increased risk of death.

The protective effect of p16(INK4a) in oral cavity carcinomas: p16(Ink4A) dampens tumor invasion-integrated analysis of expression and kinomics pathways

A large body of evidence shows that p16(INK4a) overexpression predicts improved survival and increased radiosensitivity in HPV-mediated oropharyngeal squamous cell carcinomas.(OPSCC). Here we demonstrate that the presence of transcriptionally active HPV16 in oral cavity squamous cell carcinomas does not correlate with p16(INK4a) overexpression, enhanced local tumor immunity, or improved outcome. It is interesting that HPV-mediated oropharyngeal squamous cell carcinomas can be categorized as having a 'nonaggressive' invasion phenotype, whereas aggressive invasion phenotypes are more common in HPV-negative squamous cell carcinomas. We have developed primary cancer cell lines from resections with known pattern of invasion as determined by our validated risk model. Given that cell lines derived from HPV-mediated oropharyngeal squamous cell carcinomas are less invasive than their HPV-negative counterparts, we tested the hypothesis that viral oncoproteins E6, E7, and p16(INK4a) can affect tumor invasion. Here we demonstrate that p16(INK4a) overexpression in two cancer cell lines (UAB-3 and UAB-4), derived from oral cavity squamous cell carcinomas with the most aggressive invasive phenotype (worst pattern of invasion type 5 (WPOI-5)), dramatically decreases tumor invasiveness by altering expression of extracellular matrix remodeling genes. Pathway analysis integrating changes in RNA expression and kinase activities reveals different potential p16(INK4a)-sensitive pathways. Overexpressing p16(INK4a) in UAB-3 increases EGFR activity and increases MMP1 and MMP3 expression, possibly through STAT3 activation. Overexpressing p16(INK4a) in UAB-4 decreases PDGFR gene expression and reduces MMP1 and MMP3, possibly through STAT3 inactivation. Alternatively, ZAP70/Syk might increase MUC1 phosphorylation, leading to the observed decreased MMP1 expression.

The significant association of CCND1 genotypes with colorectal cancer in Taiwan

Colorectal cancer, one million cases of diagnosis worldwide annually, is one of the most common malignant tumors and 20 % incidence caused by low penetrance susceptibility genes. Cyclin D1 (CCND1) regulating cell cycle transition may determine the susceptible individuals to genomic instability and carcinogenesis. The study aimed at examining the contribution of CCND1 genotypes to colorectal cancer risk in Taiwan. The genotypes of CCND1 A870G (rs9344) and G1722C (rs678653) were determined among 362 colorectal cancer patients and 362 age- and gender-matched cancer-free controls. Significant differences were observed between colorectal cancer and control groups in the distributions of genotypic (P = 9.71 × 10(-4)) and allelic (P = 0.0017) frequencies at CCND1 A870G. Additionally, individuals carried AG or GG genotype had 0.56- or 0.51-fold higher of odds ratios for developing colorectal cancer than the AA genotype (95 % confidence intervals = 0.40-0.78 and 0.32-0.81, respectively). Furthermore, G allele of CCND1 A870G performed a protective effects for nonsmokers and nonalcohol drinkers (P = 0.0012 and 0.0007, respectively) on colorectal cancer risk. These findings support the concept that the cell cycle regulation may play a role in colorectal cancer initiation and development and CCND1 A870G genotyping maybe a feasible technology for colorectal cancer early detection.

Interactions between clinical factors, p16, and cyclin-D1 expression and survival outcomes in oropharyngeal and hypopharyngeal squamous cell carcinoma

BACKGROUND

P16 and cyclin-D1 are cell cycle proteins commonly dysregulated in head and neck carcinoma. We assessed their expression, clinicopathological variables, and overall survival (OS) in oropharyngeal and hypopharyngeal squamous cell carcinoma (SCC).

METHODS

Clinical characteristics and p16 and cyclin-D1 expression were evaluated in 101 patients with oropharyngeal SCC and 75 patients with hypopharyngeal SCC. Associations with OS were assessed using Cox regression and Kaplan-Meier analysis.

RESULTS

Compared to oropharyngeal SCC, patients with hypopharyngeal SCC were older, men, ever-smokers with higher mean Charlson Comorbidity Index (CCI), lower p16 expression, and poorer median OS (24.8 vs 62.3 months; p < .01). In oropharyngeal SCC, CCI (p < .001), cyclin-D1 (hazard ratio [HR] = 3.55; p = .007), current smoking (HR = 5.72; p = .004), and former smoking (HR = 4.12; p = .035) were independently associated with OS. In hypopharyngeal SCC, only nodal and Eastern Cooperative Oncology Group status were associated with OS.

CONCLUSION

In oropharyngeal SCC, cyclin-D1 expression is correlated with survival, whereas smoking status and CCI may allow further stratification of outcome.

Contribution of personalized Cyclin D1 genotype to triple negative breast cancer risk

Aim: Cell cycle regulator cyclin D1 (CCND1) is a pivotal regulator for G1/S phase transition, playing a critical part in initiation of carcinogenesis. Triple negative breast cancer comprises a very heterogeneous group of cancer cells, but little is known about what is wrong in the genome of these patients. This study investigated contribution of CCND1 genotype to individual triple negative breast cancer susceptibility. Materials: In all, 2464 native Taiwan subjects consist of 1232 breast cancer cases and 1232 controls were enrolled in a hospital-based, case-control study. CCND1 A870G (rs9344) genotyping was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Risk-stratified analyses correlated genotype and age-related characteristics of breast cancer subgroups. Results: No significant difference was found between patient and control groups in distribution of genotypic and allelic frequencies in CCND1 genotype, yet CCND1 A870G (rs9344) GG genotype was far less prevalent in breast cancer patients younger than 55 years (OR=0.62, 95%CI=0.43-0.89, P=0.0362), with first menarche earlier than 12.2 years (OR=0.61, 95% CI=0.42-0.87, P=0.0241), with menopause earlier than 49.0 years (OR=0.57, 95%CI=0.39-0.82, P=0.0093), or showing triple-negative breast cancer (OR=0.28, 95%CI=0.13-0.62, P=0.0006). Such valuable findings suggest CCND1 A870G (rs9344) as a predictive marker for triple negative breast cancer in Taiwanese women; the authors sincerely hope these help us fight the toughest subtype in clinical management.

The significance of p53 immunoexpression with different clones (DO-7 and PAb-240) in oral squamous cell carcinoma

BACKGROUND/AIM

The TP53 gene is a tumor suppressor gene. Its product is a nuclear protein that regulates cell cycle arrest, apoptosis and DNA repair. Anti-p53 clones DO-7 and PAb-240 recognize the amino acid sequences 21-25 and 213-217, respectively. This study aimed to evaluate the expression of these clones and their relationship with clinicopathological features and survival analysis in oral squamous cell carcinomas (OSCC).

METHODS

Information on 53 primary OSCC was collected at the Brazilian National Cancer Institute. An immunohistochemical method was applied to evaluate p53 expression (DO-7 and PAb-240). Their expression was analyzed quantitatively and correlated with clinicopathological features. Kaplan-Meier survival curves and log rank test were used.

RESULTS

Immunopositivity for DO-7 was present in 64% of the cases, while 58% were positive for PAb-240. There was no correlation between immunoexpression of both antibodies and clinicopathological features or survival analysis. DO-7 expression was significantly higher (p = 0.001) than that of PAb-240.

CONCLUSIONS

There were quantitative differences between the expression of the antibodies studied, which may reflect a different specificity of each one. To confirm immunohistochemical results and estimate the true prognostic role of TP53 in OSCC, it is important to perform mutation analysis.

Distinct involvement of 9p21-24 and 13q14.1-14.3 chromosomal regions in raw betel-nut induced esophageal cancers in the state of Meghalaya, India

BACKGROUND

Raw betel nut (RBN) chewing is an important contributing factor for esophageal squamous cell carcinoma (ESCC), although associated genomic changes remain unclear. One difficulty in assessing the effects of exclusively RBN induced genetic alterations has been that earlier studies were performed with samples of patients commonly using tobacco and alcohol, in addition to betel-quid. Both CDKN2A (at 9p21) and Rb1 gene (at 13q14.2) are regarded as tumor suppressors involved in the development of ESCC. Therefore, the present study aimed to verify the RBN's ability to induce ESCC and assess the involvement of CDKN2A and Rb1 genes.

METHODS

A panel of dinucelotide polymorphic markers were chosen for loss of heterozygosity studies in 93 samples of which 34 were collected from patients with only RBN-chewing habit. Promoter hypermethylation was also investigated.

RESULTS

Loss in microsatellite markers D9S1748 and D9S1749, located close to exon 1β of CDKN2A/ARF gene at 9p21, was noted in 40% ESCC samples with the habit of RBN-chewing alone. Involvement of a novel site in the 9p23 region was also observed. Promoter hypermethylation of CDKN2A gene in the samples with the habit of only RBN-chewing alone was significantly higher (p=0.01) than Rb1 gene, also from the samples having the habit of use both RBN and tobacco (p=0.047).

CONCLUSIONS

The data indicate that the disruption of 9p21 where CDKN2A gene resides, is the most frequent critical genetic event in RBN-associated carcinogenesis. The involvement of 9p23 as well as 13q14.2 could be required in later stages in RBN-mediated carcinogenesis.

Histological and immunohistochemical study of the expression of p53 and ki-67 proteins in the mucosa of the tongue, pharynx and larynx of rats exposed to cigarette smoke

INTRODUCTION

Head and neck cancers are linked to smoking. The most affected sites are the oral cavity, pharynx and larynx. Experimental studies show epithelial lesions caused by cigarette smoke.

OBJECTIVES

To investigate in rats the effects of acute cigarette smoke exposure on the mucosa of the tongue, pharynx and larynx.

MATERIAL AND METHOD

Wistar rats were allocated into two groups of 20 animals: CG (control) receiving food and water ad libitum and TG (Tobacco) exposed to the smoke of 40 cigarettes/day for 60 days. Biopsy of their tongues, pharynxes and larynxes were subjected to histopathological, histomorphometric and immunohistochemical studies of protein p53 and ki-67.

RESULT

The histological analysis of tongue from the Tobacco group revealed epithelial hyperplasia (90%), basal cell hyperplasia (95%) and mild to moderate dysplasia (85%). In pharynx showed basal cell hyperplasia (85%), dysplasia (25%) and vascular congestion (95%). In larynx showed basal cell hyperplasia (70%), epithelial hyperplasia (55%), congestion (100%) and inflammatory infiltrate (25%). Morphometric analysis revealed that keratin layer thickness was greater in the tobacco group. P53 immunoexpression was negative in both groups. Ki-67 immunoexpression was positive in basal cell nuclei but in parabasal cell nuclei it was positive only in the Tobacco group.

CONCLUSIONS

The exposure of animals to cigarette smoke for 60 days resulted in benign lesions. The duration of exposure was not enough to cause the development cancer, as confirmed by the negative expression of p53 protein in all slides examined. Analysis of ki-67 expression showed intense epithelial proliferation in response to damage.

Cyclin D1 polymorphism and oral cancer: a meta-analysis

Cyclin D1 (CCND1) plays a critical role in the G1 to S-phase cell cycle transition. Data on the association between the CCND1 A870G polymorphism and oral cancer are conflicting. To assess the relationship between the CCND1 A870G genotype and the risk of developing oral cancer, we performed a meta-analysis. We searched PubMed to December 1, 2011, for studies on this topic that had been published in the English. For each study, we calculated odds ratios (ORs) and 95 % confidence intervals (CIs), assuming the frequency of allele comparison, homozygote comparison, recessive and dominant genetic models. We then calculated pooled ORs and 95 % CIs. Seven studies were included in the meta-analysis. The CCND1 G allele was not associated with oral cancer in the frequency of allele comparison (G vs. A: OR = 0.882; 95 % CI = 0.684-1.137; p = 0.001 for heterogeneity). In the subgroup analysis, the CCND1 G allele was associated with a borderline significantly decreased risk of developing oral cancer in Asians in the frequency of allele comparison (G vs. A: OR = 0.800; 95 % CI = 0.636-1.006; p = 0.089 for heterogeneity), and the association between the GG genotype and oral cancer was significant in Asians with respect to both the homozygote comparison (GG vs. AA: OR = 0.644; 95 % CI = 0.491-0.843; p = 0.186 for heterogeneity) and the dominant genetic model (GG + AG vs. AA: OR = 0.713; 95 % CI = 0.584-0.870; p = 0.293 for heterogeneity). Our analysis provides evidence that genotypes for the CCND1 A870G polymorphism may be associated with an increased risk of developing oral cancer in the Asian population.

Bcl-xL protein: predictor of complete tumor response in patients with oral cancer treated with curative radiotherapy

BACKGROUND

We earlier observed altered expression of p53 and Bcl-xL in oral cancer cell lines/tissues and wanted to evaluate these proteins for prediction of radiotherapy response and outcome.

METHODS

Thirty-nine paraffin-embedded, pretreatment oral cancer biopsies were analyzed for protein expression using immunohistochemistry and correlated with tumor response to radiotherapy and disease-free survival (DFS).

RESULT

High p53 (p = .040) was observed in female versus male patients. Increased p53 intensity (p = .063) was observed in tobacco habitués (chewers ± smokers) versus patients with no habits. In univariate analysis, nodal positivity (p = .044) and favorable/complete tumor response (p = .002) exhibited a significant correlation with DFS, whereas tumor response emerged as an independent predictor of DFS in multivariate analysis. Significantly high Bcl-xL (p = .048) was observed in the unfavorable versus favorable responders.

CONCLUSION

Our study suggests that Bcl-xL expression along with clinical parameters may be useful for identifying patients with oral cancer likely to draw maximum benefit from curative radiotherapy.

The role of human papillomavirus in the pathogenesis of head & neck squamous cell carcinoma: an overview

Cancer statistics report an increased incidence of OSCC and OPSCC around the world. Though improvements in screening and early diagnosis have dramatically reduced the incidence of this neoplasm in recent years, the 5-year-disease-free survival, is still poor, specially for oropharyngeal cancer, despite the great scientific and financial efforts. Recently, several papers showed that HPV may be involved at least in the pathogenesis of a subgroup of oral and cervical SCC, leading to distinct molecular characteristics compared with HPV-negative ones. Nevertheless, OPSCCs associated with HPV infection seem to show a better prognosis and affect younger patients (< 40 yrs.), especially females. Therefore, there is the need to properly assess oropharyngeal SCC subgroups: 1) not HPV associated/classic oral SCC: less responsive to anticancer drugs: needs novel post-surgical treatment; 2) HPV associated/oral SCC: needs several management options and suitable "target" therapy against the virus, and/or immune-stimulating therapy. Further issues are: 1) the disclosure of putative targets for more efficient molecular therapy, which may work as cervical cancer post-surgical treatment, in anticipation of the effects of "global prevention" performed by WHO anti-HPV vaccination programs; 2) careful identification of precancerous lesions in both sites; dysplasia is currently treated by excisional or ablative procedures, which don't consider the concept of field carcinogenesis. In fact, it is probable that near or far from an excised precancerous lesion new foci of cell transformation may exist, which are not yet macroscopically evident, but, if detected, would put the patient into a high risk subgroup.Comparing findings reported in the recent literature, the data of this state of the art about HPV might add useful informations concerning oropharyngeal carcinogenesis. Moreover, our review would be useful in order to define novel perspectives of treatment choice for Head & Neck cancer patients, by combining well known chemotherapeutical drugs with new molecular "target" therapy.

p16(INK4a)/CDKN2 expression and its relationship with oral squamous cell carcinoma is our current knowledge enough?

Oral squamous cell carcinomas (OSCC) are the most common malignancy of the oral cavity and their multistep development requires the accumulation of multiple genetic and epigenetic alterations. Inactivation of p16(INK4a), encoded by the CDKN2 gene has been widely associated with this type of tumors. The purpose of this review is to elucidate the relationship between p16(INK4a) expression and the different clinical and pathological aspects of OSCC, analyze the variation in results between studies, detailing the described genetic/epigenetic alterations that result in gene silencing and the relationship between p16(INK4a) and HPV infection.

Guggulsterone targets smokeless tobacco induced PI3K/Akt pathway in head and neck cancer cells

Background

Epidemiological association of head and neck cancer with smokeless tobacco (ST) emphasizes the need to unravel the molecular mechanisms implicated in cancer development, and identify pharmacologically safe agents for early intervention and prevention of disease recurrence. Guggulsterone (GS), a biosafe nutraceutical, inhibits the PI3K/Akt pathway that plays a critical role in HNSCC development. However, the potential of GS to suppress ST and nicotine (major component of ST) induced HNSCC remains unexplored. We hypothesized GS can abrogate the effects of ST and nicotine on apoptosis in HNSCC cells, in part by activation of PI3K/Akt pathway and its downstream targets, Bax and Bad.

Methods and Results

Our results showed ST and nicotine treatment resulted in activation of PI3K, PDK1, Akt, and its downstream proteins - Raf, GSK3β and pS6 while GS induced a time dependent decrease in activation of PI3K/Akt pathway. ST and nicotine treatment also resulted in induction of Bad and Bax phosphorylation, increased the association of Bad with 14-3-3ζresulting in its sequestration in the cytoplasm of head and neck cancer cells, thus blocking its pro-apoptotic function. Notably, GS pre-treatment inhibited ST/nicotine induced activation of PI3K/Akt pathway, and inhibited the Akt mediated phosphorylation of Bax and Bad.

Conclusions

In conclusion, GS treatment not only inhibited proliferation, but also induced apoptosis by abrogating the effects of ST / nicotine on PI3K/Akt pathway in head and neck cancer cells. These findings provide a rationale for designing future studies to evaluate the chemopreventive potential of GS in ST / nicotine associated head and neck cancer.

Prognostic significance of immunohistochemical biomarkers in oral squamous cell carcinoma

Advances in understanding of the molecular mechanisms underlying oral squamous cell carcinoma (OSCC) have resulted in an increasing number of biomarkers that can be used to predict the behaviour of this disease. The authors conducted a literature review of studies examining the role of immunohistochemistry-based protein biomarkers in predicting OSCC outcome. Only articles published in PubMed-indexed journals over the past 5 years were considered. 22 molecular biomarkers were identified and classified into five groups based on their biological functions: cell cycle acceleration and proliferation; tumour suppression and apoptosis; hypoxia; angiogenesis; and cell adhesion and matrix degradation. The cell cycle acceleration and proliferation biomarkers showed the most divergent prognostic findings. Studies on tumour suppression and apoptosis biomarkers were the most prevalent. There were only a few studies examining molecular biomarkers of hypoxia and angiogenesis, and studies examining cell adhesion and matrix degradation biomarkers have shown that this group has the greatest potential for assessing prognostic parameters. Amongst the several proteins analysed, the immunohistochemical expression levels of epithelial growth factor receptor (EGFR), p53, and matrix metalloproteinases (MMPs) have demonstrated the greatest potential for survival prediction in OSCC, but this review demonstrates that their prognostic relevance is debatable and requires further standardisation.

A systematic review of p53 as a prognostic factor of survival in squamous cell carcinoma of the four main anatomical subsites of the head and neck

OBJECTIVES

To summarize existing evidence about whether the presence of mutant or upregulated p53 is a prognostic factor for patients presenting with squamous cell carcinoma arising from the larynx, oropharynx, hypopharynx, or oral cavity.

METHOD

Relevant articles were identified using strict criteria for systematic searches. Associations between mutant or upregulated p53 versus wild-type or low/undetectable p53 in relation to overall survival and DFS were summarized by extracting or deriving hazard ratio (HR) estimates. Random-effects meta-analyses were used to account for between-study heterogeneity and to summarize the effect of p53 across studies.

RESULTS

The meta-analyses gave a statistically significant pooled HR for overall survival in oral cavity [pooled HR, 1.48; 95% confidence interval, (95% CI), 1.03-2.11], and for disease-free survival in oral cavity (pooled HR, 1.47; 95% CI, 1.12-1.93) and in oropharynx (pooled HR, 0.45; 95% CI, 0.27-0.73). Despite attempts to limit it, between-study heterogeneity was large in the majority of meta-analyses and the prognostic value of p53 was generally inconsistent and inconclusive across studies.

CONCLUSION

The meta-analysis results highlight that current evidence about the prognostic value of p53 in patients with squamous cell carcinoma of the head and neck is inconclusive. Large heterogeneity exists across studies in study-level and patient-level characteristics, making it difficult to ascertain a clear picture. Future studies are required in which p53 expression is investigated in a more standardized and biologically informative manner. In particular, prospectively planned individual patient data meta-analyses are needed to establish the prognostic importance of p53 for specific subgroups of patients undergoing specific treatments.

Prognostic significance of molecular markers in oral squamous cell carcinoma: a multivariate analysis

BACKGROUND

Multiple marker accumulation impacts tumor progression and biologic phenotypes affect clinical outcome of patients with head and neck cancer. Hence, this study investigated a battery of molecular markers that may help to reflect biologic aggressiveness and predict prognosis.

METHODS

Epidermal growth factor receptor (EGFR), Stat3, H-ras, c-myc, p53, cyclin D1, p16, Rb, Ki-67, and Bcl-2 were localized immunohistochemically in 135 oral squamous cell carcinoma patients to assess prognostic value.

RESULTS

In univariate analysis of total patients, p53, Stat3, and p16 predicted both relapse-free survival (RFS) and overall survival (OS). In Cox multivariate analysis, after adjusting for tumor size, nodal status, and lymphatic permeation, p53 was independently associated with RFS and OS, and p16 with RFS only. In only early-stage patients, in univariate analysis, nuclear Stat3 was significant for RFS and OS.

CONCLUSION

Immunostaining of p53, p16, and Stat3 might serve as potential adjuncts in pathologic evaluation of oral tumors to predict risk of relapse.

Differential roles of p16INK4A and p14ARF genes in prognosis of oral carcinoma

BACKGROUND

Oral cancer patients are found to have poor clinical outcome and high disease recurrence rate, in spite of an aggressive treatment regimen. The inactivation of INK4A/ARF loci is reported to be second to p53 inactivation in human cancers. The purpose of this study was to assess the prognostic significance of the molecular aberrations in the INK4A locus for effective identification of aggressive oral carcinoma cases needing alternate therapy.

MATERIALS AND METHODS

The study composed of 116 patients freshly diagnosed with oral carcinoma. The genetic and epigenetic status of the p16(INK4A) and p14(ARF) genes was evaluated. The relation between these genic alterations and different treatment end points, such as residual disease (initial response), disease recurrence, and overall survival, along with the standard clinical markers, were analyzed.

RESULTS

62% of the study cases had p16(INK4A) gene abnormalities, with deletion accounting for 33% and methylation for 29%. Alterations in p14(ARF) gene either by deletion (12%) and/or methylation (18%) were observed in 30% of the cases. p16(INK4A) deletion was associated with aggressive tumors, as evidenced by the nodal involvement of the disease. Low or absence of p16(INK4A) protein adversely affected the initial treatment response. Promoter methylation of p16(INK4A) was associated with increased disease recurrence and acts as an independent predictor for worse prognosis. Surprisingly, p14(ARF) methylation associated with lower recurrence rate in oral cancer patients with a good clinical outcome. Overall survival of these patients was associated with tumor size, nodal disease, and p16(INK4A) protein expression pattern. Our results indicate that p16(INK4A) and p14(ARF) alterations constitute a major molecular abnormality in oral cancer cases.

CONCLUSION

The molecular profile of INK4A/ARF locus, both at DNA and protein level, could be used as a prognostic biomarker for assessing the aggressiveness of disease in oral carcinoma patients. The study further shows the opposing clinical effect of these two genes, transcribed from the same locus, in oral cancer patients.

H-Ras mutation modulates the expression of major cell cycle regulatory proteins and disease prognosis in oral carcinoma

Activating mutations of the Ras is a moderately frequent event in oral carcinogenesis in Indian patients. Ras pathway has essential roles in regulation of various phases of the cell cycle, especially at G1 phase. Despite a large body of in vitro evidence, the multidimensional interaction between mutated Ras pathway and G1 cell cycle regulatory proteins in tumours in vivo is poorly determined. In the present study, DNA samples were screened for mutations in hot spot exons of B-Raf and hot spot codons 12, 13 and 61 of H-, K- and N-Ras by PCR-SSCP. Mutations were confirmed by direct sequencing. Expression of G1 cell cycle regulatory proteins-cyclin D1, CDK4, Rb, p53, p16 and p21 and proliferation marker PCNA was analysed immunohistochemically. The results revealed the absence of B-Raf mutations in oral carcinoma in spite of 12.5% of the samples showing H-Ras mutation. The H-Ras mutant cases showed significantly low cyclin D1 (P=0.027) and CDK4 (P=0.046) expression and overexpression of Rb (P=0.011) and p16 (P=0.026). H-Ras mutant carriers also had significantly high recurrence-free survival (P=0.033). In summary the present study demonstrated an epistatic interaction between H-Ras mutation and G1 cell cycle regulatory proteins in vivo. H-Ras mutation, thus, defines a molecular subtype of oral carcinoma with favourable outcome and unique biology.

Curcumin down regulates smokeless tobacco-induced NF-κB activation and COX-2 expression in human oral premalignant and cancer cells

Smokeless tobacco (ST) consumption is a major cause of oral cancer in South East Asia including India. Recently, we showed that exposure to smokeless tobacco extract (STE) (khaini) results in increased expression and activation of nuclear factor-kappaB (NF-kappaB) and its downstream target cyclooxygenase-2 (COX-2) in human oral cell systems in vitro. The present study was designed to test the hypothesis that curcumin may inhibit the activation of NF-kappaB in ST exposed oral premalignant and cancer cells. Exposure of oral premalignant and cancer cells to curcumin resulted in significant decrease in cell viability and induced apoptosis. STE-induced nuclear translocation and DNA-binding activity of NF-kappaB were inhibited in curcumin pretreated oral premalignant and cancer cells in vitro. Curcumin treatment led to decreased expression of NF-kappaB and COX-2. The tobacco specific nitrosamine, 4-(methylnitrosamino-)-1-(3-pyridyl)-1-butanone (NNK), is one of the carcinogenic components of STE (khaini). We demonstrate that curcumin pretreatment abrogated NNK-induced activation of NF-kappaB and COX-2 expression, suggesting that NNK is one of the factors in STE (khaini) modulated by curcumin. In conclusion, our findings demonstrate for the first time that curcumin downregulates STE (khaini) or NNK-induced NF-kappaB and COX-2 in oral premalignant and cancer cells in vitro.

Carcinoma of tongue and the buccal mucosa represent different biological subentities of the oral carcinoma

PURPOSE

Clinico-epidemiological studies show that the behaviour of the tongue cancer is different from the cancer originating at other sites of the oral cavity. However, studies identifying the reason for such difference are lacking in the literature.

METHODS

In the present study, we have attempted to see whether any difference existed in the cell cycle regulatory mechanism of these tumours by comparing immunohistochemically the expression of major cell cycle regulatory proteins in 147 buccal and 94 tongue carcinoma (anterior two-third of tongue) prospectively.

RESULTS

On comparison of buccal and tongue carcinoma, expression of p16 and p21 showed significant difference. In combined analysis, simultaneous down regulation of p16 and p21 was seen in 47% of tongue cancer cases as against 28% in buccal carcinoma (P=0.004). In univariate analysis, none of the clinico-biological variables studied showed significant association with survival in tongue carcinoma, whereas, some of the clinico-biological variables associated with survival in buccal carcinoma. Among the biological markers, the overexpression of cyclin D1 (P=0.007) and p53, detected using both the clones of antibodies-DO7 (P=0.008) and PAb240 (P=0.014) and the down regulation of p16 (0.033), showed significant association with shorter disease free survival (DFS) in these cases. Whereas in the case of overall survival (OS), overexpression of p53 [DO7 (P=0.031) and PAb240 (P=0.017)] and cyclin D1 (P=0.001) associated with poor survival. In multivariate analysis, the expression pattern of p53 and p16 protein influences the DFS whereas cyclin D1 expression showed independent association with the OS in buccal carcinoma.

CONCLUSIONS

Thus, tongue and buccal cancers represent different biological subentities, and such differences should be considered in oral cancer management.

Influence of single nucleotide polymorphisms in H-Ras and cyclin D1 genes on oral cancer susceptibility

Although tobacco usage and alcohol consumption are the major risk factors for oral cancer, there are individual variations in genetic susceptibility to oral cancer. The Ras pathway plays an important role in oral carcinogenesis. High percentage of Ras mutation in oral carcinoma was reported from India. Cyclin D1, a downstream member of the Ras pathway, was also shown to be overexpressed in the majority of oral cancers and the overexpression was shown to be associated with poor prognosis. In the present study, we have evaluated the association of the single nucleotide polymorphisms in the H-Ras (C81T) and cyclin D1 (A870G and C1722G) genes and oral cancer risk in 176 oral cancer cases and 142 hospital based controls matched by age and sex. All the polymorphisms studied conformed to Hardy-Weinberg equilibrium. The comparison of the CCND1 A870G and C1722G genotype frequencies in cases and controls did not show any significant association with oral cancer risk. In H-Ras C81T polymorphism, TC+CC genotype showed a one and half fold increased risk (OR=1.59) for oral cancer. On stratified analysis, the observed increased risk was more evident among men (OR=2), while such an increased risk was not seen among women. Thus, our data suggests that the variant 'C' allele of the H-Ras (C81T) is associated with a higher risk for oral carcinoma, particularly in male population and thus, this polymorphism could be a low penetrance gene predisposition factor for oral carcinoma.