The retinoic acid receptor-beta (RAR-beta) mRNA expression in the oral squamous cell carcinoma associated with betel quid use

Alcohol Drinking Obliterates the Inverse Association Between Serum Retinol and Risk of Head and Neck Cancer

This analysis evaluated the association between serum retinol levels and risk of head and neck cancer (HNC) and whether the association is modulated by the use of alcohol, betel quid, or cigarette. In addition, we also examined the association between HNC risk and 2 single nucleotide polymorphisms, TTR rs1667255 and RBP4 rs10882272, that have been associated with serum retinol levels. Unconditional logistic regression was performed to evaluate the association between serum retinol levels and HNC risk among 160 HNC cases and 198 controls. The associations between TTR rs1667255 and RBP4 rs10882272 and serum retinol levels or HNC risk were evaluated by linear regression and unconditional logistic regression, respectively, for 418 HNC cases and 497 controls. The results showed that HNC cases had a lower mean serum retinol level compared with controls (845.3 μg/L vs 914.8 μg/L, P = 0.03). An inverse association between serum retinol levels and HNC risk occurred among never/occasional alcohol drinkers but not among regular drinkers. TTR rs1667255 was associated with serum retinol levels; however, neither TTR rs1667255 nor RBP4 rs10882272 was associated with HNC risk. In summary, this study showed an inverse association between serum retinol levels and HNC risk, specifically among never/occasional alcohol drinkers. More studies are needed to establish the underlying biologic mechanisms for the inverse association between serum retinol levels and HNC risk and the modulation of this relationship by alcohol drinking.

Methylation-associated gene silencing of RARB in areca carcinogens induced mouse oral squamous cell carcinoma

Regarding oral squamous cell carcinoma (OSCC) development, chewing areca is known to be a strong risk factor in many Asian cultures. Therefore, we established an OSCC induced mouse model by 4-nitroquinoline-1-oxide (4-NQO), or arecoline, or both treatments, respectively. These are the main two components of the areca nut that could increase the occurrence of OSCC. We examined the effects with the noncommercial MCGI (mouse CpG islands) microarray for genome-wide screening the DNA methylation aberrant in induced OSCC mice. The microarray results showed 34 hypermethylated genes in 4-NQO plus arecoline induced OSCC mice tongue tissues. The examinations also used methylation-specific polymerase chain reaction (MS-PCR) and bisulfite sequencing to realize the methylation pattern in collected mouse tongue tissues and human OSCC cell lines of different grades, respectively. These results showed that retinoic acid receptor β (RARB) was indicated in hypermethylation at the promoter region and the loss of expression during cancer development. According to the results of real-time PCR, it was shown that de novo DNA methyltransferases were involved in gene epigenetic alternations of OSCC. Collectively, our results showed that RARB hypermethylation was involved in the areca-associated oral carcinogenesis.

DNA hypermethylation as an epigenetic mark for oral cancer diagnosis

Oral cancer is the largest group of cancers which fall into the head and neck category. While genetic alterations in oral cancer have long been documented, the effect of epigenetic changes is more recent. The recent explosion in science of how chromatin organization modulates the gene expression has highlighted the epigenetic mechanism of oral cancer pathogenesis. DNA methylation, which is an important epigenetic marker, is perhaps the best characterized chemical modification of mammalian DNA and provides a stable, heritable, and critical component of epigenetic regulation. This review attempts to decipher the epigenetic aspects of oral cancer by evaluating the DNA methylation status through its various stages from normal to potentially malignant to malignant states. In doing so, we emphasize DNA methylation as a novel biomarker in oral cancer research, thus opening newer avenues in oral cancer research.

Detection and screening of oral cancer and pre-cancerous lesions

Oral cancer is a fatal disease, accounting for the fourth highest incidence of malignancy in males and the seventh in females in Taiwan. The relatively high prevalence of oral cancer in Taiwan is mainly because there is a high-risk group of 2.5 million people with the habit of smoking and betel nut chewing. Unfortunately, 50% of new cases in our medical center who present with TNM stage III or IV lesions have a shorter than 5-year survival after treatment. This highlights the need for: (1) early treatment of fresh oral cancer cases; (2) screening of the high-risk population to detect new lesions; (3) careful follow-up of cases after treatment; and (4) detection of occult early neck nodal adenopathy in surgical cases. It is generally accepted that prevention and screening of oral cancer are equally important to treatment due to its location. In this review article, we describe the nature of oral cancer and highlight the various conventional and novel methods of screening for this disease and ongoing important related research. Related literature is reviewed and future work that needs to be done is detailed.

Up-regulation of inflammatory signalings by areca nut extract and role of cyclooxygenase-2 -1195G>a polymorphism reveal risk of oral cancer

Because the mRNA expression of cyclooxygenase-2 (COX-2) is up-regulated by arecoline in human gingival fibroblasts, as shown in our previous study, we further investigated the mRNA expression level of COX-2 and its upstream effectors in three oral epithelial carcinoma cell lines (KB, SAS, and Ca9-22) by using areca nut extract (ANE) and saliva-reacted ANE (sANE). A case-control study of 377 oral squamous cell carcinoma (OSCC) patients and 442 controls was conducted to evaluate the gene-environment interaction between COX-2 promoter polymorphisms and substance use of alcohol, betel quid, and cigarettes (ABC) in risk of OSCC. The heterogeneous characteristics of the oral site and the COX-2 -1195G>A polymorphism in these cell lines showed diverse inflammatory response (KB>>Ca9-22>SAS) after 24-hour ANE/sANE treatments, and the COX-2 up-regulation might be mostly elicited from alternative nuclear factor-kappaB activation. In the case-control study, betel chewing [adjusted odds ratios (aOR), 42.2] posed a much higher risk of OSCC than alcohol drinking and cigarette smoking (aORs, 2.4 and 1.8, respectively), whereas the COX-2 -1195A/A homozygote presented a potential genetic risk (OR, 1.55). The strongest joint effect for OSCC was seen in betel chewers with -1195A/A homozygote (aOR, 79.44). In the non-betel chewing group, the -1195A/G and A/A genotypes together with the combined use of alcohol and cigarettes increased risk to 15.1-fold and 32.1-fold, respectively, compared with the G/G genotype without substance use. Taken together, these findings illustrate a valuable insight into the potential role of the COX-2 promoter region in contributing to the development of betel-related OSCC, including ANE/sANE-induced transcriptional effects and enhanced joint effects of COX-2 -1195A allele with substance use of ABC.

An investigation of the differential expression of Her2/neu gene expression in normal oral mucosa, epithelial dysplasia, and oral squamous cell carcinoma in Taiwan

BACKGROUND

Her2/neu was thought to be a proto-oncogene with sequence homology to epidermal growth factor receptor (EGFR). Its overexpression was seen in many cancers and referred to regimens of anticancer therapy. The aim of this study was to investigate whether the abnormal expression existed in oral carcinogenesis.

METHODS

Immunohistochemistry (IHC) was used to detect Her2/neu expression in normal oral mucosa (NOM) (n = 20), oral precancerous lesions of epithelial dysplasia (ED) (n = 20), and oral squamous cell carcinoma (OSCC) (n = 30). The association of clinicopathologic covariates of areca use, tumor size, neck lymph node metastasis, differentiation and stages of cancer with the expression of Her2/neu was examined. The significance of Neu immunoreactivity in different groups or with different covariates was investigated using Fisher's exact test.

RESULTS

Her2/neu immunoreactivity was very low with Her2/neu(+) in 10% (2/20) of NOM cases and in 25% (5/20) of ED cases, respectively. The Her2/neu expression was high in OSCC cases, with 40% (12/30) of Her2/neu(+) and 10% (3/30) of Her2/neu(++). Significant difference was observed between NOM/ED and OSCC cases (p < 0.05). All clinicopathologic covariates showed no significant relation to the expression of Her2/neu in OSCC cases.

CONCLUSION

These findings suggested a dynamic change in Her2/neu expression during the development of OSCC. The overexpression of Her2/neu can be used as a marker in distinguishing NOM/ED from OSCC.

Functional polymorphism in NFKB1 promoter is related to the risks of oral squamous cell carcinoma occurring on older male areca (betel) chewers

Areca (betel)-chewing is tightly associated with the high prevalence of oral squamous cell carcinoma (OSCC) in Asians. NFKB1 encodes a 105kDa protein that can be processed to produce p50 subunit of nuclear factor-kappaB protein complex. A insertion (ins)/deletion (del) polymorphism (-94ins/delATTG) in NFKB1 promoter, which may drive the ins allele two-fold increase in NFKB1 transcription relative to del allele, was recently found. This study identified that the odds ratio in OSCC carrying ins allelotype were 1.78 relative to controls (56.7 vs 41.8%) in subjects more than 50 years old. L allelotype of Heme oxygenase-1 (HO-1), accounting for a long (GT)(n) repeat in HO-1 promoter, is associated with the risks of areca-related OSCC. Subjects carried both NFKB1 ins and HO-1 L allelotypes had significant risks for various subsets of OSCC. OSCC with lymph node metastasis or advanced stage had significantly higher frequency of NFKB1 ins and HO-1 L allelotypes. This study suggested that the functional NFKB1promoter polymorphism could be valuable for assessment of cancer risk.

Clinical significance of altered expression of retinoid receptors in oral precancerous and cancerous lesions: Relationship with cell cycle regulators

Alterations in expression of retinoid receptors are implicated in human cancers. We hypothesized that altered expression of retinoic acid receptors (RARalpha,beta,gamma) and retinoid X receptor RXRalpha and their relationship with cell cycle regulators (p53, p16, p21) is associated with development, progression and prognosis of oral cancer. Immunohistochemical analysis of RAR alpha, beta, gamma and RXRalpha proteins was carried out on serial sections from 244 oral squamous cell carcinomas (OSCCs), 102 potentially malignant lesions (65 hyperplasias, 37 dysplasias), 83 matched histologically normal oral tissues and 29 normal mucosa from non-exposed individuals without oral lesions and correlated with expression of cell cycle regulators p53, p16 and p21 as well as with clinicopathological parameters. Expression of retinoid receptors RARbeta, RARgamma, RXRalpha and cell cycle regulators p16 and p21 was decreased in majority of oral SCCs as well as in potentially malignant lesions. Multivariate stepwise logistic regression analysis carried out for comparison of non-exposed normal oral mucosa with histologically normal oral tissues from patients with oral lesions showed significant loss of RARbeta or p53 accumulation (RARbeta(-)/p53(+) Odd's ratio, OR = 266.6, p = 0.000); non-exposed normal mucosa from individuals without oral lesions with potentially malignant lesion was RARbeta(-)/p21(-)/p53(+) (OR = 215.7, p = 0.000); matched normal to potentially malignant stage was RARalpha(+)/p21(-) (OR = 4.414, p = 0.005); hyperplasia to dysplasia was RARalpha(+)/p53(+) (OR = 4.72, p = 0.005) and potentially malignant to malignant phenotype was RARalpha(+) (OR = 2.061, p = 0.004). The prognostic relevance of these factors was assessed in 115 of these SCC patients who were followed-up for a maximum period of 94 months (median 21 months). Multivariate analysis using Cox's proportional Hazard's model showed that RARalpha(+)/p21(-) phenotype was associated with shorter disease-free survival (Hazard's ratio, HR = 1.863, p = 0.0471). To our knowledge, this is the first large study showing alterations in expression of retinoid receptors at the protein level at different stages in development and progression of oral SCC. It also underscored the prognostic significance of retinoid receptors and their interactions with cell cycle regulators in multistep oral tumorigenesis.

Habitual risk factors for head and neck cancer

Chronic tobacco smoking and alcohol consumption are well-established risk factors for the development of squamous cell carcinoma (SCC) of the head and neck. There are, however, a variety of other habitual and culturally based activities that are less commonly seen in the Western world and that are also risks factors for the development of this type of cancer. In this era of globalization, many of these habits have now crossed borders and appear in various areas throughout the world. This article reviews habitual and social risk factors for cancer of the head and neck, excluding smoking and alcohol consumption. These factors include chewing tobacco and snuff, areca nut in its various forms, Khat leaves, and the drinking of Mate.

EBM RATING

D.

Polymorphism in heme oxygenase-1 (HO-1) promoter is related to the risk of oral squamous cell carcinoma occurring on male areca chewers

Areca (betel) chewing is associated with the high incidence of oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF) in Asians. Heme oxygenase-1 (HO-1), encoding an oxidative response protein, plays protective roles in cells. A (GT)_n microsatellite repeat in HO-1 promoter shows polymorphisms and modulates the level of gene transcription. We examined allelotypic frequencies of (GT)_n repeats in 83 controls, 147 OSCC and 71 OSF. All subjects were male areca chewers. Logistic regression was used to adjust the age confounding for odds ratio (OR). (GT)_n repeat polymorphism was classified into short (S), medium (M) and long (L) alleles. The adjusted OR in OSCC subjects carrying L allelotype relative to S allelotype was 1.75. Buccal squamous cell carcinoma (BSCC) is the most common OSCC subset in areca chewers. L allelotype implied the risk of BSCC with adjusted OR of 2.05, whereas M allelotype appeared protective for non-BSCC with adjusted OR of 0.49. Our findings indicated that longer (GT)_n repeat allele in HO-1 promoter is associated with the risks of areca-related OSCC, while the shorter (GT)_n repeat allele may have protective effects for OSCC.

Correlation between functional genotypes in the matrix metalloproteinases-1 promoter and risk of oral squamous cell carcinomas

BACKGROUND

Oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF), which are highly associated with areca use, are prevalent in most Asian countries. Matrix metalloproteinases (MMPs) are superfamily of metal-dependent proteolytic enzymes, mediating the degradation of extracellular matrix. Insertion/deletion (-1607 2G-->1G) polymorphism has been described in the promoter region of the human matrix metalloproteinases-1 (MMP-1) genes, which cause an alteration in the transcriptional activity. This genotype is associated with risks of cancer genesis and metastasis. In this paper, we studied the relationship between such genotype and areca-associated oral diseases.

METHODS

Genomic DNA from the blood of OSCC (n = 121), OSF (n = 58) cases and controls (n = 147) were amplified by polymerase chain reaction (PCR)-based genotyping. The OSCC were further grouped into buccal squamous cell carcinoma (BSCC) and non-buccal suqmaous cell carcinoma (NBSCC), in accord with the site of involvement. The significance of the differences was assessed by Fisher's exact test.

RESULTS

The 2G genotype in MMP-1 promoter was observed with a higher frequency in both OSCC (0.69, P = 0.06) and NBSCC (0.76, P = 0.03) cases compared with controls (0.63), with an odds ratio of 2.17 and 4.58, respectively. This genotype was not related to the risk of OSF. No other clinicopathologic parameter was associated with the genotypes in OSCC cases.

CONCLUSION

The results showed that 2G genotype in MMP-1 promoter was associated with the risk of OSCC.

Cyclin D1 genotype in areca-associated oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most common malignancy in areca-chewing regions, accounting for up to 50% of malignant tumors in some South Asian countries. Amplification and/or over-expression of cyclin D1 (CCND1) is a frequent event in human malignancies, including OSCC. CCND1 G870A polymorphism (codon 242) gives rise to two isoforms of the protein. The objective of the present study was to evaluate if the risk, onset, and prognosis of areca-associated OSCC is related to CCND1 genotypes.

METHODS

We analyzed the CCND1 genotype in 70 OSCC cases and 93 control Taiwanese using single-strand conformation polymorphism techniques.

RESULTS

Statistical analysis showed that CCND1 genotype had no impact on the risk, onset, or survival of areca-associated OSCC. However, buccal squamous cell carcinoma (BSCC) appeared to be less frequently associated with AA genotype than non-BSCC (P = 0.02). In addition, amplification of CCND1 was significantly more prevalent in OSCC cases (22%) than in control subjects (2%, P < 0.01).

CONCLUSION

This study demonstrates that the CCND1 genotype may confer different risks for BSCC and non-BSCC.