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

Computational Exploration of Single-Nucleotide Polymorphisms in the Human hRAS Gene: Implications and Insights

Background A group of genes called oncogenes includes the Harvey rat sarcoma virus (hRAS) gene. Along with hRAS, Kirsten rat sarcoma viral oncogene homolog (kRAS) and neuroblastoma RAS viral oncogene homolog (nRAS) genes belong to the Rat sarcoma (Ras) family of oncogenes. These three genes result in Rho guanosine triphosphate hydrolases (GTPases) as their protein product. Instructions for producing the protein hRAS, which is mainly involved in controlling cell division, are provided by the hRAS gene. The hRAS protein transfers signals from outside through a process called signal transduction. Because the hRAS protein is a GTPase, it changes the chemical guanosine-5'-triphosphate (GTP) into guanosine diphosphate (GDP). GTP and GDP molecules operate as switches to turn on and off the hRAS. This study aimed to anticipate the structure and stability of the protein resulting from missense single-nucleotide polymorphisms (SNPs) in the human hRAS genes. Methodology To investigate the possible negative effects associated with these SNPs, bioinformatic analysis is typically essential. The following tools were employed for forecasting harmful SNPs: Scale-Invariant Feature Transform (SIFT), Protein Analysis Through Evolutionary Relationships (PANTHER), non-synonymous SNP by Protein Variation Effect Analyzer (PROVEAN), and non-synonymous SNP by Single Nucleotide Polymorphism Annotation Platform (SNAP). Results The present study identified a total of 11 SNPs using the SIFT approach, which were shown to have functional significance. Only two of these 11 SNPs were determined to be tolerable, whereas nine were shown to be detrimental. Among the 11 SNPs analyzed, seven (Q61H, Q99H, K117R, A121D, A146V, R169W, R169Q) were classified as possibly damaging,and four (G13V, Q22K, Q61K, Q13V) were categorized as probably benign according to the predictions made by PANTHER tools. Therefore, the seven SNPs were identified as high-risk SNPs. Conclusions Given that SNPs have the potential to be candidates for cellular alterations brought on by mutations that are associated with cancer, this study provides vital information about how SNPs might be utilized as a diagnostic marker for cancer.

Cell Cycle Regulatory CCND1 G870A Gene Polymorphism and Periodontitis-Induced Oral Cancer: A Risk Analysis

Strong association has been recently observed between periodontitis/gingivitis and Oral squamous cell carcinoma (OSCC). A high incidence of oral cancer has been reported in the case of chronic periodontitis. Recently Cell cycle regulatory /Senescence genes have been associated with Gingivitis/ Periodontitis susceptibility. Cyclin D1 is one such cell cycle regulatory gene. Several findings have reported that Cyclin D1 (CCND1) G870A Single nucleotide polymorphism is associated with oral cancer (OC) risk, but yielded inconsistent data across different studies. This meta-analysis explores the precise relationship between CCND1 G870A polymorphism and OC risk. PubMed (Medline), EMBASE, & Google Scholar databases were searched for eligible studies and pooled odds ratios (ORs) and 95% confidence intervals (CI) were calculated. Newcastle-Ottawa analysis was done for selected articles quality assessment, bias in publication (if any) was estimated through Funnel plots and Egger’s test. Pooled analysis from eleven eligible studies suggests that CCND1 G870A polymorphism is not significantly associated with OC risk. Sub-group analysis by ethnicity failed to show any association. Sequential single study omission was performed to determine the credibility and resilience of the inferences drawn.

Inhibitory Effects of Glucosylceramide on Tumorigenesis Induced by a Carcinogen in Mice

Objective

Glucosylceramide (Glu‐Cer), a glycosylated form of ceramide, has been reported to have cytotoxic effects in the cells of various cancers. We previously reported that dietary Glu‐Cer from rice bran had inhibitory effects on human head and neck squamous cell carcinoma (HNSCC) in nonobese diabetes (NOD)/severe combined immunodeficiency (SCID) mice. In HNSCC, preventing recurrence and second primary cancer is required to improve prognosis. The purpose of the present study was to determine whether dietary Glu‐Cer had anticarcinogenic and antitumorigenic effects in a mouse model of HNSCC.

Methods

A total of 40 CB6F1‐Tg rasH2@Jcl mice were divided into two groups: control and Glu‐Cer. All mice were given 4‐nitroquinoline 1‐oxide for 24 weeks. Control group mice were fed the normal diet without Glu‐Cer. The Glu‐Cer group mice were given a mixture of the normal diet plus 0.25% Glu‐Cer for 24 weeks. Microscopic examination was performed to identify grossly visible preneoplasms and neoplasms in the mouth, pharynx, and esophagus. Epithelial regions were classified as normal tissue, carcinoma in situ (CIS), or SCC; and the number of each type of region was counted.

Results

Compared with the Glu‐Cer group mice, control group mice more frequently developed individual and multiple tumors of each type, including CIS and SCC, in the mouth, pharynx, or esophagus.

Conclusion

Tumor development was effectively inhibited by dietary Glu‐Cer derived from rice bran, indicating that this and related compounds show promise as prophylactic agents for human HNSCC.

Level of Evidence

NA Laryngoscope, 130:E593–E597, 2020

Association between Cyclin D1 G870A (rs9344) polymorphism and cancer risk in Indian population: meta-analysis and trial sequential analysis

Introduction: Association between Cyclin D1 (CCND1) single nucleotide polymorphism (SNP) rs9344 and cancer risk is paradoxical. Thus, we performed a meta-analysis to explore the association between CCND1 variant and overall cancer risk in Indian population. Methods: Data from 12 published studies including 3739 subjects were collected using Pubmed and Embase. RevMan (Review Manager) 5.3 was used to perform the meta-analysis. OR with 95%CI were calculated to establish the association. Results: Overall, the cumulative findings demonstrated that CCND1 polymorphism (rs9344) was not significantly associated with cancer risk in all the genetic models studied (dominant model: GG vs GA+AA: OR (95%CI) = 0.81 (0.60-1.09), P=0.17; recessive model: GG+GA vs AA: OR (95%CI) = 1.23 (0.96-1.59), P=0.11; co-dominant model: GG vs AA: OR (95%CI) = 1.35 (0.93-1.97), P=0.12; co-dominant model: (GG vs GA: OR (95%CI) = 1.16 (0.85-1.59), P=0.34; allelic model: A vs G: OR (95%CI) = 1.20 (1.14-2.85), P=0.23; allelic model: G vs A: OR (95%CI) = 0.83 (0.62-1.12), P=0.23). Subgroup analysis according to cancer types presented significant association of CCND1 polymorphism and increased breast cancer risk in dominant model (GG vs GA+AA: OR = 2.75, 95%CI = 1.54-4.90, P=0.0006) and allelic model (G vs A: OR = 1.63, 95%CI = 1.22-2.19, P=0.001). An increased esophageal cancer risk in recessive model (GG+GA vs AA: OR = 1.51, 95%CI = 1.05-2.16, P=0.03) and co-dominant model (GG vs AA: OR = 2.51, 95%CI = 1.10-5.71, P=0.03) was detected. A higher risk for colorectal cancer was detected under both the co-dominant models (GG vs AA: OR = 2.46, 95%CI = 1.34-4.51, P=0.004 and GG vs GA: OR = 1.74, 95%CI = 1.14-2.67, P=0.01). However, in case of cervical cancer risk a non-significant association was reported under the recessive model (GG+GA vs AA: OR = 1.52, 95%CI = 0.60-3.90, P=0.38) with reference to CCND1 polymorphism (rs9344). The trial sequential analysis (TSA) showed that the cumulative Z-curve neither crossed the trial sequential monitoring boundary nor reached the required information size (RIS). Thus, present meta-analysis remained inconclusive due to insufficient evidence. Conclusion:CCND1 polymorphism rs9344 may not have a role in overall cancer susceptibility in Indian population. However, this polymorphism acts as a crucial risk factor for breast, esophageal, and colorectal cancer but not for cervical cancer. Future studies with larger sample size are required to draw a reliable conclusion.

Identification of a novel HRAS variant and its association with papillary thyroid carcinoma

HRas proto-oncogene (HRAS) is one of the most commonly mutated genes in thyroid cancer, with mutations frequently occurring in the follicular and Hurthle cell subtypes. However, the contribution of mutations in HRAS to papillary thyroid carcinoma (PTC) progression and the tall-cell variant (TCV) is poorly understood. The aim of the present study was to investigate the somatic genetic variants present in HRAS in patients with PTC, and to investigate the association of these mutations with PTC. The present study is a retrospective case-control study using tumor samples collected from 139 patients with PTC and blood samples from 195 healthy individuals. All patient samples were screened for mutations in 'hotspot' regions of HRAS and B-raf proto-oncogene (BRAF) by single-stranded conformational polymorphism analysis, followed by direct sequencing. A novel variant (IVS1-82del gctgggcctggg) in the HRAS 5'-untranslated region was identified. There was no difference in age or sex of patients with PTC and the healthy controls; however, the HRAS variant was more frequently detected in PTC tissue than in the healthy control samples (37 vs. 26%, P=0.04). There was no association between the HRAS variant and age, sex, tumor size, encapsulation, multifocality/intra-thyroidal spread, Tumor-Node-Metastasis stage, history of Hashimoto's disease, BRAF V600E mutation or PTC subtype (all P>0.05). There were differences of BRAF V600E distribution among different subtypes (χ²=6.390, P=0.041). HRAS variant co-occurring with the BRAF V600E mutation accounted for 31.6% of the total number (P=0.196). Therefore, this novel variant of HRAS (IVS1-82del gctgggcctggg) may be associated with PTC; however, larger scale studies are required to assess the contribution of this novel HRAS variant to PTC progression.

Association Between Polymorphism rs678653 in Human Cyclin D1 Gene (CCND1) and Susceptibility to Cancer: A Meta-Analysis

Background

To assess the association between polymorphism rs678653 in human Cyclin D1 gene (CCND1) and the risk of cancer.

Material/Methods

Multiple biomedical databases were systematically searched. Pooled odds ratios (OR) and 95% confidence intervals (95% CIs) were calculated in the appropriate model.

Results

In total, 17 case-control studies from 14 articles were included. When combing all available data, no significant association of rs678653 with cancer risk was observed under different genetic models. Stratification by ethnicity also indicated that rs678653 was not correlated with cancer risk in Taiwanese or Indian populations. When stratified by cancer type, no significant association was found between polymorphism rs678653 and digestive tract cancer, head and neck cancer, and gynecological cancer risk.

Conclusions

Our comprehensive meta-analysis suggests that the polymorphism rs678653 in CCND1 has no association with cancer risk in different population and disease contexts, indicating that CCND1 rs678653 does not serve a significant biological function in predicting cancer risk.

Association between the Cyclin D1 G870A polymorphism and the susceptibility to and prognosis of upper aerodigestive tract squamous cell carcinomas: an updated meta-analysis

PURPOSE

Several publications have investigated the association between the Cyclin D1 G to A substitution at nucleotide 870 (CCND1 G870A) polymorphism and squamous cell carcinoma (SCC) of the upper aerodigestive tract (UADT), but their conclusions still remain controversial. We conducted a meta-analysis to precisely evaluate this association.

PATIENTS AND METHODS

We electronically searched the Chinese National Knowledge Infrastructure, PubMed, and Embase (up to January 2015) databases for case-control studies on the association between the CCND1 G870A polymorphism and SCC of the UADT, and 23 studies were included in total.

RESULTS

The meta-analysis results showed that there was a significant association between the CCND1 G870A polymorphism and the risk of SCC of the UADT (AA vs GG: odds ratio [OR] =1.33, 95% confidence interval [CI] =1.01-1.74, P<0.001 for heterogeneity; GA/AA vs GG: OR =1.24, 95% CI =1.01-1.51, P<0.001 for heterogeneity; AA vs

GA/GG

OR =1.16, 95% CI =0.97-1.39, P<0.001 for heterogeneity; allele A vs allele G: OR =1.14, 95% CI =1.00-1.30, P<0.001 for heterogeneity; GA vs GG: OR =1.18, 95% CI =0.98-1.42, P<0.001 for heterogeneity). However, when analyzing prognosis, allele G was a potential risk factor for poor tumor differentiation (AA vs

GA/GG

OR =2.60, 95% CI =1.15-5.86, P=0.836 for heterogeneity) and reduced disease-free intervals (OR =2.08, 95% CI =1.17-3.69, P=0.134 for heterogeneity). In the subgroup analysis, the cancer susceptibility of Asian groups, population-based control groups, nasopharyngeal cancer groups, and esophageal SCC groups were more likely to be affected by the CCND1 G870A polymorphism. No significant publication bias was found in our analysis (P=0.961 for Egger's test and P=0.245 for Begg's test).

CONCLUSION

The results of the present meta-analysis suggest that the variant CCND1 870A allele might confer an elevated risk of SCC of the UADT, particularly among Asians and individuals who have esophageal or nasopharyngeal cancers. Moreover, the CCND1 870A allele might also confer better tumor differentiation grades and longer disease-free intervals.

Association of cyclin D1 variants with head and neck cancer susceptibility: evidence from a meta-analysis

Whether cyclin D1 (CCND1) gene variants increase susceptibility to head and neck cancer (HNC) is undetermined. Therefore, we performed the present meta-analysis to systematically assess any possible association between CCND1 variants (G870A and G1722C) and HNC risk. Seventeen studies for CCND1 G870A and three studies for CCND1 G1722C were included. Overall, CCND1 polymorphisms (G870A and G1722C) had no association with increased HNC risk (p>0.05). In the subgroup analysis by smoking status, significantly increased HNC risk was found among smokers under allele contrast, homozygous comparison and recessive models (p<0.05), smoking carriers of A allele and AA genotype appearing at elevated risk. In conclusion, while there was overall a lack of any association between CCND1 polymorphisms (G870A and G1722C) and HNC risk, smokers carrying the A allele and AA genotype of the CCND1 G870A polymorphism may be susceptible to HNC development.

Polymorphism T81C in H-RAS Oncogene Is Associated With Disease Progression in Imatinib (TKI) Treated Chronic Myeloid Leukemia Patients

Background

Mammalian cells contain three functional RAS proto-oncogenes, known as H-RAS, K-RAS, and N-RAS, which encode small GTP-binding proteins in terms of p21^rass. RAS genes have been elucidated as major participants in the development and progression of cancer. A single nucleotide polymorphism (SNP) at H-RAS cDNA position 81 T→C (rs12628) has been found to be associated with the risk of many human cancers like gastrointestinal, oral, colon, bladder and thyroid carcinomas. Therefore, we hypothesized that this polymorphisms in H-RAS could influence susceptibility to chronic myeloid leukemia as well, and we conducted this study to test the hypothesis in Indian population.

Method

H-RAS polymorphism was studied in 100 chronic myeloid leukemia (CML) patients and 100 healthy controls by restriction fragmentation length polymorphism (RFLP-PCR). Associations between polymorphism and clinicopathological features of CML patients were investigated.

Results

In CML patients, the TT, TC and CC genotype frequency was 38%, 61% and 1% respectively, compared to 92%, 8% and 0% in healthy controls respectively. Compared to TT genotype, CT was significantly associated with increased risk of CML (odds ratio (OR): 8.4, P < 0.00001). There was a statistically significant correlation of H-RAS polymorphism with phases (P < 0.0003), molecular response (P < 0.0001), hematological response (P < 0.04) and thrombocytopenia (P < 0.003). However, there was no correlation of this polymorphism found with other clinical parameters.

Conclusion

H-RAS T81C polymorphism was found to be associated with CML risk and prognosis of CML. These results suggest that C heterozygosis may be considered a potential risk factor for CML development in the North Indian population.

Cutaneous epithelial tumors induced by vemurafenib involve the MAPK and Pi3KCA pathways but not HPV nor HPyV viral infection

The inhibitors of mutant BRAF that are used to treat metastatic melanoma induce squamoproliferative lesions. We conducted a prospective histopathological and molecular study on 27 skin lesions from 12 patients treated with vemurafenib. Mutation hot spots in HRAS, NRAS, KRAS, BRAF, and Pi3KCA were screened. HPV and HPyV infection status were also determined. The lesions consisted of 19 verrucal papillomas, 1 keratoacanthoma and 7 squamous cell carcinomas. No mutations were found within BRAF and NRAS. KRAS, HRAS, and Pi3KCA oncogenic mutations were found in 10 (83.3%), 7 (58.3%), and 4 (33.3%) patients respectively; however, these mutations were not consistent within all tumors of a given patient. Pi3KCA mutation was always associated with a mutation in HRAS. Finally, no correlation was found between the mutated gene or type of mutation and the type of cutaneous tumor or clinical response to vemurafenib. P16 protein level was not indicative of HPV infection. HPV was detected in only two lesions. Two cases had MCPyV, and one had HPyV7. In conclusion, neither HPV nor HPyV seem to be involved in the development of squamoproliferative lesions induced by verumafenib. By contrast, HRAS and KRAS play a predominant role in the physiopathology of these tumors.

Cyclin D1 G870A polymorphism and risk of nasopharyngeal carcinoma: a meta-analysis

Recently, there have been a number of studies on the association between cyclin D1 G870A polymorphism and nasopharyngeal carcinoma risk. However, the results of previous reports remain controversial and ambiguous. Thus, we performed a meta-analysis to explore more precisely the association between cyclin D1 G870A polymorphism and the risk of nasopharyngeal carcinoma. No significant association was found between cyclin D1 G870A polymorphism and nasopharyngeal carcinoma risk in total population analysis. In the subgroup meta-analysis by ethnicity, a negative association was shown in Caucasian subgroup, and no significant association in any genetic models among Asians was observed. In summary, positive results have been shown on the search for polymorphic variants influencing the risk of NPC. This meta-analysis provides evidence of the association between CCND1 G870A polymorphism and NPC risk, supporting the hypothesis that CCND1 870A allele probably acts as an important NPC protective factor in Caucasians but not in Asians. Since the results of our meta-analysis are preliminary and may be biased by the relatively small number of subjects, they still need to be validated by well-designed studies using larger samples in the future.

Association between functional polymorphisms in genes involved in the MAPK signaling pathways and cutaneous melanoma risk

Genome-wide association studies (GWASs) have mainly focused on top significant single nucleotide polymorphisms (SNPs), most of which did not have clear biological functions but were just surrogates for unknown causal variants. Studying SNPs with modest association and putative functions in biologically plausible pathways has become one complementary approach to GWASs. To unravel the key roles of mitogen-activated protein kinase (MAPK) pathways in cutaneous melanoma (CM) risk, we re-evaluated the associations between 47 818 SNPs in 280 MAPK genes and CM risk using our published GWAS dataset with 1804 CM cases and 1026 controls. We initially found 105 SNPs with P ≤ 0.001, more than expected by chance, 26 of which were predicted to be putatively functional SNPs. The risk associations with 16 SNPs around DUSP14 (rs1051849) and a previous reported melanoma locus MAFF/PLA2G6 (proxy SNP rs4608623) were replicated in the GenoMEL dataset (P < 0.01) but failed in the Australian dataset. Meta-analysis showed that rs1051849 in the 3' untranslated regions of DUSP14 was associated with a reduced risk of melanoma (odds ratio = 0.89, 95% confidence interval: 0.82-0.96, P = 0.003, false discovery rate = 0.056). Further genotype-phenotype correlation analysis using the 90 HapMap lymphoblastoid cell lines from Caucasians showed significant correlations between two SNPs (rs1051849 and rs4608623) and messenger RNA expression levels of DUSP14 and MAFF (P = 0.025 and P = 0.010, respectively). Gene-based tests also revealed significant SNPs were over-represented in MAFF, PLA2G6, DUSP14 and other 16 genes. Our results suggest that functional SNPs in MAPK pathways may contribute to CM risk. Further studies are warranted to validate our findings.

Lack of association of the cyclin D1 G870A variation with oral carcinoma risk: Evidence from 2,404 subjects

Evidence implicates cyclin D1 (CCND1) G870A polymorphisms as risk factors for various cancers. An increasing number of investigations have been conducted on the association of CCND1 G870A polymorphisms with susceptibility to oral carcinoma, and have yielded inconclusive results. The aim of the present study was to derive a more precise estimation of the correlation. Meta-analyses examining the association between CCND1 G870A polymorphisms and oral carcinoma were performed. Separate analyses on ethnicity, smoking status and control sources were also implemented. Eligible studies were identified prior to February 2012. From the overall data from 1,128 cases and 1,276 controls, no associations of CCND1 G870A polymorphisms with oral carcinoma were observed [AA vs. GG: odds ratio (OR)=1.06; 95% confidence interval (CI), 0.62-1.82; dominant model: OR=1.04; 95% CI, 0.76-1.43; recessive model: OR=1.06; 95% CI, 0.70-1.59]. In the subgroup analysis by ethnicity, smoking status and control sources, no significant associations of CCND1 G870A polymorphisms and oral cancer were observed for the three genetic models. Collectively, the data failed to suggest CCND1 G870A polymorphism as a low-penetrant risk factor for developing oral carcinoma. Additional studies with large sample sizes concerning different ethnicities in different areas are required.

Lack of mutational events of RAS genes in sporadic thyroid cancer but high risk associated with HRAS T81C single nucleotide polymorphism (case-control study)

High incidence of thyroid cancer worldwide indicates the importance of studying genetic alterations that lead to its carcinogenesis. Specific acquired RAS mutations have been found to predominate in different cancers, and HRAS T81C polymorphism has been determined to contribute the risk of various cancers, including thyroid cancer. We screened the exons 1 and 2 of RAS genes (HRAS, KRAS, and NRAS) in 60 consecutive thyroid tissue (tumor and adjacent normal) samples, and a case-control study was also conducted for HRAS T81C polymorphism in HRAS codon 27 using the polymerase chain reaction-restriction fragment length polymorphism to test the genotype distribution of 140 thyroid cancer patients in comparison with 170 cancer-free controls from a Kashmiri population. No mutation was found in any of the thyroid tumor tissue samples, but we frequently detected polymorphism at nucleotide 81 (T > C) in exon 1 of HRAS gene. In HRAS T81C SNP, frequencies of TT, TC, and CC genotypes among cases were 41.4, 38.6, and 20.0 %, while in controls genotype frequencies were 84.1, 11.7, and 4.2 %, respectively. A significant difference was observed in variant allele frequencies (TC + CC) between the cases and controls (58.6 vs. 16 %) with odds ratio = 7.4; confidence interval (CI) = 4.3-12.7 (P < 0.05). Interestingly, combined TC and CC genotype abundantly presented in follicular thyroid tumor (P < 0.05). Moreover, a significant association of the variant allele (TC + CC) was found with nonsmokers (P < 0.05). This study shows that although thyroid cancer is highly prevalent in this region, the mutational events for RAS genes do not seem to be involved. Contrary to this HRAS T81C SNP of HRAS gene moderately increases thyroid cancer risk with rare allele as a predictive marker for follicular tumors.

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.

Biomarkers of oral premalignant epithelial lesions for clinical application

Oral cancer is the sixth most common form of cancer worldwide, and the majority of cases occur in India and Southeast Asia. Its major risk factors in the western world include smoking and drinking alcohol, whereas in Asia, it is primarily caused by tobacco/areca nut/betel leaf chewing and/or human papillomavirus (HPV) infections. Little is known about this type of cancer despite recent advances in cancer biology. The generally asymptomatic nature of the early oral lesions causes them to remain undetected in many cases. Thus, the disease progresses substantially before the patients seek treatment and is a major contributing factor to the severity of this disease. Therefore, there is a great need to create awareness for its prevention and early diagnosis. The application of advanced molecular biological and biochemical methodologies to elucidate its biomarkers may aid in early detection; however, much more work must be done for this information to be effectively applied in the clinical setting. This review focuses on the need for systematic diagnoses in the early detection of oral cancer using molecular and biochemical approaches, thereby reducing the number of advanced cases in the chewing tobacco-dominated oral cancer population.

Paternal age effect mutations and selfish spermatogonial selection: causes and consequences for human disease

Advanced paternal age has been associated with an increased risk for spontaneous congenital disorders and common complex diseases (such as some cancers, schizophrenia, and autism), but the mechanisms that mediate this effect have been poorly understood. A small group of disorders, including Apert syndrome (caused by FGFR2 mutations), achondroplasia, and thanatophoric dysplasia (FGFR3), and Costello syndrome (HRAS), which we collectively term "paternal age effect" (PAE) disorders, provides a good model to study the biological and molecular basis of this phenomenon. Recent evidence from direct quantification of PAE mutations in sperm and testes suggests that the common factor in the paternal age effect lies in the dysregulation of spermatogonial cell behavior, an effect mediated molecularly through the growth factor receptor-RAS signal transduction pathway. The data show that PAE mutations, although arising rarely, are positively selected and expand clonally in normal testes through a process akin to oncogenesis. This clonal expansion, which is likely to take place in the testes of all men, leads to the relative enrichment of mutant sperm over time-explaining the observed paternal age effect associated with these disorders-and in rare cases to the formation of testicular tumors. As regulation of RAS and other mediators of cellular proliferation and survival is important in many different biological contexts, for example during tumorigenesis, organ homeostasis and neurogenesis, the consequences of selfish mutations that hijack this process within the testis are likely to extend far beyond congenital skeletal disorders to include complex diseases, such as neurocognitive disorders and cancer predisposition.

The effect of CCND1 +870A>G and VEGF +936C>T polymorphisms on oral cancer development and disease-free survival in a Taiwan population

The association between polymorphisms in vascular endothelial growth factor (VEGF) +936C>T and cyclin D1 (CCND1) +870A>G genes, oral cancer risk, and disease-free survival remains controversial. We found no association between polymorphisms in the CCND1 and VEGF genes and oral cancer development using multivariate logistic regression analysis. Clinical data indicated that the VEGF +936C>T polymorphisms were associated with larger tumor size and advanced cancer stage, but the χ(2) test did not show that CCND1 polymorphisms were associated with larger tumor size and advanced cancer stage. However, Cox proportional hazards model analysis showed no correlation between the VEGF +936C>T polymorphisms and poor disease-free survival. The CCND1 +870A>G polymorphisms (hazard ratio (HR)=1.62, 95% CI=1.10-2.46; adjusted HR=1.63, 95% CI=1.08-2.54) and larger tumor size were associated with poor 5-year disease-free survival by the log rank test and multivariate Cox proportional hazards model analysis. We hypothesized that polymorphisms in CCND1 +870A>G and VEGF +936C>T genes are not correlated with the development of oral cancer. We found the CCND1 +870G allele to be an independent risk factor for poor 5-year disease-free survival in oral cancer patients. VEGF +936C>T polymorphisms were not directly correlated with poor survival, but they might be associated with increased tumor size, which affected our disease-free survival results.

Ras oncogenes in oral cancer: the past 20 years

Oral squamous cell carcinoma (OSCC) of head and neck is associated with high morbidity and mortality in both Western and Asian countries. Several risk factors for the development of oral cancer are very well established, including tobacco chewing, betel quid, smoking, alcohol drinking and human papilloma virus (HPV) infection. Apart from these risk factors, many genetic factors such as oncogenes, tumor suppressor genes and regulatory genes are identified to involve in oral carcinogenesis with these risk factors dependent and independent manner. Ras is one of the most frequently genetically deregulated oncogene in oral cancer. In this review, we analyze the past 22years of literature on genetic alterations such as mutations and amplifications of the isoforms of the ras oncogene in oral cancer. Further, we addressed the isoform-specific role of the ras in oral carcinogenesis. We also discussed how targeting the Akt and MEK, downstream effectors of the PI3K/Akt and MAPK pathways, respectively, would probably pave the possible molecular therapeutic target for the ras driven tumorigenesis in oral cancer. Analysis of these ras isoforms may critically enlighten specific role of a particular ras isoform in oral carcinogenesis, enhance prognosis and pave the way for isoform-specific molecular targeted therapy in OSCC.

Polymorphic variants of H-RAS protooncogene and their possible role in bladder cancer etiology

Introduction

H-RAS gene is a protooncogene encoding p21ras, a small protein with GTPase activity. This protein is a component of many signaling cascades, while mutations in H-RAS gene are often found in urinary bladder cancer and leads to continuous transmission of signals stimulating cancer cell growth and proliferation. The T81C polymorphism of H-RAS gene is a SNP, which, although does not seem to impair p21ras protein structure and function, may contribute to the development of bladder cancer.

Objectives

The aim of our study was to characterize the prevalence and clinical significance of T81C polymorphism in patients with diagnosed bladder cancer.

Materials and methods

132 patients with diagnosed urinary bladder cancer were included in this study. The control group consisted of 106 healthy individuals. The experimental material was DNA, isolated from tumor tissue and peripheral blood lymphocytes. T81C polymorphism was detected using the MSSCP method and DNA sequencing.

Results

In the examined DNA samples, frequent polymorphic variations were found in codon 27 of H-RAS gene. In order to assess the clinical relevance of the polymorphism, the results were compared with those for the control group. The homozygous CC variant occurred more frequently in bladder cancer patients than in healthy individuals.

Conclusions

DNA polymorphisms start to play an important role in evaluation of disease risk and progression. The occurrence of multiple variants of the same gene may contribute to differences in reactions to specific medications and sensitivity to carcinogens or DNA repair capacity. Our study demonstrated T81C polymorphism of H-RAS gene to have seemingly been associated with an increased risk of bladder cancer development.

HRAS T81C polymorphism modulates risk of urinary bladder cancer and predicts advanced tumors in ethnic Kashmiri population

OBJECTIVE

Specific acquired HRAS mutations have been found to predominate in bladder cancer, and HRAS T81C polymorphism has been determined to contribute the risk of various cancers, including bladder cancer.

MATERIALS AND METHODS

We screened the exon 1and 2 of HRAS and frequently detected polymorphism at nucleotide 81T to C (exon 1). A case-control study was conducted using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to test the genotype distribution of 140 bladder cancer patients in comparison with 160 cancer-free controls from a Kashmiri population.

RESULTS

In HRAS T81C SNP, frequencies of TT, TC, and CC genotypes among controls were 84.4%, 15.6%, and 0.0%, while in cases allele frequencies were 64.3%, 30%, and 5.7%, respectively. A significant differences was observed between the control and cases with odds ratio (OR) = 3.0 and 95% confidence interval (CI) = 1.74-5.20 (P = 0.000). Interestingly, combined TC and CC genotype abundantly presented in high grade (OR = 5.4 and 95% CI = 2.8-10.2; P < 0.00) and in advanced tumors (OR = 3.3, 95% CI = 1.71-6.30; P < 0.05). A significant association of the variant allele (TC+CC) was found with male subjects (≥50) and ever smokers (P = 0.001).

CONCLUSION

It is evident from our study that HRAS T81C SNP moderately increases bladder cancer risk, and rare allele is a predictive marker of advanced bladder tumors.

Association of cyclin D1 gene polymorphisms with risk of esophageal squamous cell carcinoma in Kashmir Valley: a high risk area

Investigation of potential association of SNPs (G870A, rs9344; G1722C, rs678653) of cyclin D1 gene (CCND1) with susceptibility to esophageal squamous cell carcinoma (ESCC) in Kashmir valley (India). The study included 302 subjects comprising 151 ESCC cases and 151 controls. PCR-RFLP and direct sequencing were employed for genotyping. The G870A polymorphism, the individuals carrying GA + AA genotype was having 2.80-fold increased risk for development of ESCC (OR 2.8, 95% CI = 1.77-4.4; P = 0.0001) compared to GG genotype. Further a significantly higher risk was observed in individuals who consume >3 cups per day of salted tea (OR = 5.1; 95% CI = 1.6-16.7; P = 0.0016) and had smoking habits (OR = 6.3; 95% CI = 2.9-13.9; P = 0.0005). We also demonstrate for the first time in CCND1 1722 locus, the CC genotype was strongly associated with increased risk of developing ESCC (OR = 2.58; 95% CI = 1.61-4.15; P = 0.0001). In addition, the frequency of polymorphic C allele was also found to be higher in cases (OR = 1.92; 95% CI = 1.37-2.69; P = 0.0002). There appears to be an influence of CCND1 G870A/G1772C genotypes on genetic susceptibility to ESCC.

[Study on association between an H-RAS gene polymorphism and gastric cancer development]

BACKGROUND/AIMS

Oncogenic RAS gene mutations have been frequently observed in many tumor types, and their associations with various cancers were reported. This study was conducted to evaluate the association between H-RAS T81C polymorphism and gastric cancer development.

METHODS

H-RAS T81C polymorphism was genotyped in 321 chronic gastritis (ChG) and 151 gastric cancer (GC) patients using GoldenGate Assay kit. Logistic regression analysis adjusted for age and gender was performed to identify the differences of genotype and allele distributions between the each group.

RESULTS

All ChG and GC patients were in Hardy-Weinberg equilibrium. When the frequencies of H-RAS T81C genotype in each group were compared, the homozygous type of major allele TT was more frequent in GC group (62.9%) than ChG group (57.3%), while the frequencies of heterozygous type TC and homozygous type of minor allele CC were higher in ChG group than GC group (39.3% vs. 33.8%, 3.4% vs. 3.3%, respectively). In the results of logistic regression analyses adjusted for age and gender, the odds ratios were 0.845 (0.604-1.182), 0.799 (0.556-1.147), 0.741 (0.493-1.114) and 1.094 (0.366-3.270) for allele, codominant, dominant and recessive models, respectively. However, significant difference was not observed between two groups in any models.

CONCLUSIONS

H-RAS T81C polymorphism was not associated with gastric cancer development in a Korean population.

Detection of two novel mutations and relatively high incidence of H-RAS mutations in Vietnamese oral cancer

Oral squamous cell carcinoma is the sixth most common cancer in the world and the seventh most common cancer in Vietnam. The RAS and PI3K-AKT signaling pathways play an important role in oral carcinogenesis. Our previous study on PI3K signaling pathway showed the absence of PIK3CA and PTEN gene mutations in Vietnamese oral cancer. We thus hypothesized that the RAS could be more likely activated as an upstream effector. However, the status of RAS mutations in Vietnamese oral cancer had not been studied. In the present study, Fifty six primary tumor DNA samples were screened for mutations of hot spots in exons 1 and 2 of H-RAS and a part of the samples for exon 7 of ERK2 gene in which we previously reported a mutation in an OSCC cell line. The H-RAS mutations were detected in 10 of 56 tumors (18%). Two novel mutations were found, one was an insertion of three nucleotides (GGC) between codons 10 and 11 resulting in in-frame insertion of glycine (10(Gly)11) and the other was a missense mutation in codon 62 (GAG>GGG). We also found T81C single nucleotide polymorphism in 12 of 56 tumors (22%) and there was no mutation in exon 7 of ERK2 gene. The H-RAS mutation incidence showed significant association with advanced stages of the tumor and also with well-differentiated tumor grade. Our study is the first to report H-RAS mutation from Vietnamese ethnicity, with two novel mutations and relatively high incidence of H-RAS mutations. The results suggest that RAS is an important member in the PI3K-AKT signaling and could play an important role in the tumorigenesis of oral carcinoma.

Cyclin D1 Pro241Pro (CCND1-G870A) polymorphism is associated with increased cancer risk in human populations: a meta-analysis

The G870A polymorphism in the CCND1 gene may influence cancer risk. However, data from published studies with individual low statistical power have been controversial. To evaluate whether combined evidence shows an association between this polymorphism and cancer, we considered all available studies in a meta-analysis. Sixty studies were combined representing data for 18,411 cases and 22,209 controls. In our meta-analysis, we investigated overall sample and two ethnic populations (Caucasians and Asians) as well as nine cancer subtypes. Individuals who are homozygous for A allele (AA) were found to be associated with significantly increased cancer risk in overall sample [odds ratio (OR), 1.23; 95% confidence interval (95% CI), 1.13-1.33; P <or= 0.0001], Caucasians (OR, 1.16; 95% CI, 1.07-1.26; P=0.0002), and Asians (OR, 1.26; 95% CI, 1.14-1.39; P <or= 0.001). Among the nine cancer subtypes investigated, modestly significant risk (ORs, 1.08 to 1.51; P=0.02 to 0.04) was detected in breast, colorectal, head and neck, and other cancers. Highly significant and increased risk was found to be associated with genitourinary (OR, 1.51; 95% CI, 1.20-1.89; P=0.0004) and blood-related cancers (OR, 1.62; 95% CI, 1.28-2.05; P <or= 0.0001). Individuals who are heterozygous for AG were found to be at increased risk in overall, ethnic groups, as well as breast and colorectal cancers. Significant dominant effects seem to prevail in the majority of the categories investigated, where some recessive effects were also detected. Overall, the risk effects associated with this polymorphism were small; however, due its common occurrence, it affects a large portion of the human population (AA, 25%; AG, 50%). Although the independent small risk associated with CCND1-A870G polymorphism is not clinically useful, its interaction with other genetic variants and environmental factors has been shown to be associated with further increase in cancer risk (OR, 1.6-7.1). In conclusion, our study strongly supports the increased cancer risk associated with CCND1-A870G polymorphism in the human population.

Association between H-RAS T81C genetic polymorphism and gastrointestinal cancer risk: a population based case-control study in China

Background

Gastrointestinal cancer, such as gastric, colon and rectal cancer, is a major medical and economic burden worldwide. However, the exact mechanism of gastrointestinal cancer development still remains unclear. RAS genes have been elucidated as major participants in the development and progression of a series of human tumours and the single nucleotide polymorphism at H-RAS cDNA position 81 was demonstrated to contribute to the risks of bladder, oral and thyroid carcinoma. Therefore, we hypothesized that this polymorphisms in H-RAS could influence susceptibility to gastrointestinal cancer as well, and we conducted this study to test the hypothesis in Chinese population.

Methods

A population based case-control study, including 296 cases with gastrointestinal cancer and 448 healthy controls selected from a Chinese population was conducted. H-RAS T81C polymorphism was genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) assay.

Results

In the healthy controls, the TT, TC and CC genotypes frequencies of H-RAS T81C polymorphism, were 79.24%, 19.87% and 0.89%, respectively, and the C allele frequency was 10.83%. Compared with TT genotype, the TC genotype was significantly associated with an increased risk of gastric cancer (adjusted OR = 3.67, 95%CI = 2.21–6.08), while the CC genotype showed an increased risk as well (adjusted OR = 3.29, 95%CI = 0.54–19.86), but it was not statistically significant. In contrast, the frequency of TC genotype was not significantly increased in colon cancer and rectal cancer patients. Further analysis was performed by combining TC and CC genotypes compared against TT genotype. As a result, a statistically significant risk with adjusted OR of 3.65 (95%CI, 2.22–6.00) was found in gastric cancer, while no significant association of H-RAS T81C polymorphism with colon cancer and rectal cancer was observed.

Conclusion

These findings indicate, for the first time, that there is an H-RAS T81C polymorphism existing in Chinese population, and this SNP might be a low penetrance gene predisposition factor for gastric cancer.

Gene polymorphisms related to angiogenesis, inflammation and thrombosis that influence risk for oral cancer

Genetic association studies have implicated functional DNA polymorphisms in genes encoding factors related to angiogenesis, inflammation and thrombosis with increased risk for oral squamous cell carcinoma (OSCC). This study examines possible interactions between nine such genotype polymorphisms and their combinatory effect in assessing the OSCC risk in a European population. OSCC cases (N=162) and healthy controls (N=168) of comparable age, gender, and ethnicity (Greeks and Germans) were studied. Multivariate logistic regression models were constructed in order to assess the contribution of homozygous or heterozygous variant genotypes of polymorphisms MMP-1 (-1607 1G/2G), MMP-3 (-1171 5A/6A), MMP-9 (-1562C/T), TIMP-2 (-418C/G), VEGF (+936C/T), GPI-alpha (+807C/T), PAI-1 (4G/5G), ACE (intron 16D/I) and TAFI (+325C/T) upon overall, early and advanced stages of OSCC. Four out of nine polymorphisms affecting PAI-1, MMP-9, TIMP-2 and ACE expression contributed significantly in OSCC prediction in the various logistic regression models. Based on these findings and previous reports, possible interactions of the implicated factors leading to OSCC development, as well as an algorithm of risk estimation are discussed.

A novel rasH2 mouse carcinogenesis model that is highly susceptible to 4-NQO-induced tongue and esophageal carcinogenesis is useful for preclinical chemoprevention studies

We investigated the susceptibility of 4-nitroquinoline 1-oxide (4-NQO)-induced tongue carcinogenesis in male CB6F1-Tg-rasH2 @Jcl mice (Tg mice). The Tg mice were administered 4-NQO (20 p.p.m. in drinking water) for 2, 4, 6 or 8 weeks, and thereafter they were untreated up to week 24. At week 24, a higher incidence (80%) of tongue neoplasm with dysplasia was noted in the mice that received 4-NQO for 8 weeks in comparison with the other groups (20% incidence for each) treated with 4-NQO for 2, 4 and 6 weeks. Esophageal tumors also developed in the Tg mice were 4-NQO. Immunohistochemical observation revealed that the EP receptors, especially EP(1) and EP(2), expressed in the tongue and esophageal lesions induced by 4-NQO, thus suggesting the involvement of prostaglandin (PG) E(2) and EP(1,2) receptors in the tongue and esophageal carcinogenesis. Using this animal model, we investigated the potential chemopreventive ability of pitavastatin (1, 5 and 10 p.p.m. in diet for 15 weeks), starting 1 week after the cessation of 4-NQO-exposure (20 p.p.m. in drinking water for 8 weeks). Dietary pitavastatin at 10 p.p.m. significantly reduced the incidence and multiplicity of the tongue, but not esophageal neoplasms by the modulation of prostaglandin E2 biosynthesis, EP(1) and EP(2) expression and proliferation. Our results thus suggest that a rasH2 mouse model of 4-NQO-induced tongue and esophageal carcinogenesis can be utilized for investigating the pathogenesis of cancer development in these tissues and may well prove to be useful for identifying candidate cancer chemopreventive agents for the upper digestive organs.

Aurora kinase small molecule inhibitor destroys mitotic spindle, suppresses cell growth, and induces apoptosis in oral squamous cancer cells

Mitotic Aurora kinases are required for accurate chromosome segregation during cell division. Ectopic expression of Aurora-A (Aur-A) kinase results in centrosome amplification, aberrant spindles, and consequent aneuploidy. In the present study, we showed that Aurora kinase inhibitory small molecule VX-680 inhibited histone H3 phosphorylation at Ser10, a known in vivo substrate residue of Aurora kinase, in oral squamous cell carcinoma (OSCC) KB cells. In addition, monopolar spindle structures, typical abnormalities induced by inhibition of Aur-A, were generated in VX-680-treated cells. Inhibition of Aurora kinase led to reduced KB cell growth, as assessed by MTT assay. Western blot analysis revealed that VX-680 caused cleavage of two critical apoptotic associated proteins, PARP and caspase-3. In contrast, expression of cell survival factor Bcl-2 was reduced by VX-680 treatment in a dose-dependent manner. Subsequently, nuclear characteristic of DNA fragmentation, indicative of apoptotic cell death, was clearly observed in these OSCC cells with Aurora kinase inhibitory VX-680. Taken together, we showed that Aurora kinase inhibitory VX-680 led to apoptotic cell death in OSCC cells, suggesting a novel therapeutic target in oral cancer.

Recent advances in Oral Oncology

This paper reviews the main papers related to oral squamous cell carcinoma published in 2006 in oral oncology - an international interdisciplinary journal which publishes high quality original research, clinical trials and review articles, and all other scientific articles relating to the aetiopathogenesis, epidemiology, prevention, clinical features, diagnosis, treatment and management of patients with neoplasms in the head and neck, and orofacial disease in patients with malignant disease.

Advances in the biology of oral cancer

The incidence of oral cancer remains high and is associated with many deaths in both Western and Asian countries. Several risk factors for the development of oral cancer are now well known, including smoking, drinking and consumption of smokeless tobacco products. Genetic predisposition to oral cancer has been found in certain cases but its components are not yet entirely clear. In accordance with the multi-step theory of carcinogenesis, the natural history of oral cancer seems to gradually evolve through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. A number of genomic lesions accompany this transformation and a wealth of related results has appeared in recent literature and is being summarized here. Furthermore, several key genes have been implicated, especially well-known tumor suppressors like the cyclin-dependent kinase inhibitors, TP53 and RB1 and oncogenes like the cyclin family, EGFR and ras. Viral infections, particularly with oncogenic HPV subtypes and EBV, can have a tumorigenic effect on oral epithelia and their role is discussed, along with potential therapeutic interventions. A brief explanatory theoretical model of oral carcinogenesis is provided and potential avenues for further research are highlighted.