EGFR and HER-2 oncogenes expression in an experimental model of two-stage chemically induced carcinogenesis in mouse skin.

The aim of the study was to investigate the expression of EGFR and HER-2 oncogenes using an experimental two stage chemically induced carcinogenesis protocol on the dorsal skin in FVB/N mice. Forty female FVB/N mice 4 weeks old, were grouped into one control (n = 8) and two experimental groups (Group A: n = 16, Group B: n = 16) following a randomization process. Two-stage carcinogenesis protocol, was implicated, including an initial treatment with 97.4 nmol DMBA on their shaved dorsal skin and subsequent treatments of 32.4 nmol TPA applications after 13 weeks for Group A and after 20 weeks for Group B. The control group C, received no treatment. Skin was examined weekly for tumor development. Post-experiment, animals were euthanized for tissue analysis. The histological status of the skin lesions in the experimental groups corresponded well with tumour advancement (from dysplasia to poorly-differentiated carcinoma). Tumour sections were evaluated histologically and immunohistochemically. EGFR expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 008 respectively), while tended to be higher in benign tumours (p = 079), compared to normal histology. Moreover, mean percentage of EGFR positive expression in malignant tumours was significantly higher than in benign tumours (p < 001). HER-2 expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 015 respectively), while tended to be higher in benign tumours (p = 085), compared to normal histology. Furthermore, mean percentage of HER-2 positive expression in malignant tumours was significantly higher than in benign tumours (p = 005). The study demonstrated that in FVB/N mice subjected to a two-stage chemically induced carcinogenesis protocol, there was a significant increase in the expression of EGFR and HER-2 oncogenes in precancerous and malignant skin lesions compared to normal tissue. This suggests a potentially early role of these oncogenes in the progression of skin tumours in this model.

Impact of Amplified Oncogenes on Salivary Gland Carcinomas.

In normal epithelia, proto-oncogenes regulate critical intra- or intercellular functions, including cell growth and proliferation, apoptosis, and signaling transduction from the cell periphery (extracellular space) to the nucleus mediated by different pathways. Oncogenes are the mutated or amplified forms of the corresponding proto-oncogenes that are crucially involved in cell neoplastic and malignant transformation during carcinogenesis. Salivary gland carcinomas (SGCs) demonstrate a variety of histogenetic types. They are characterized by a broad spectrum of chromosomal and gene alterations. In particular, amplifications in specific genes [human epidermal growth factor receptor 2 (HER2), human epidermal growth factor receptor 4 (HER4), epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), Mouse double minute 2 homolog (MDM2), androgen receptor (AR), programmed death (ligand 1 (PD-L1), neurogenic differentiation factor 2 (NEUROD2), phosphatidylinositol 3,4,5-trisphosphate-dependent RAC exchanger 1 protein (PREX1), cyclin-dependent kinase4/6 (CDK4/6), proline-rich acidic protein 1 (PRAP1), kell antigen system (KEL), glutamate receptor subunit epsilon 2 (GRIN2D), Ewing sarcoma RNA-binding protein 1 (EWSR1), MYC proto-oncogene (MYC)] combined or not with chromosomal numerical imbalances (aneuploidy/ polysomy/monosomy) form different genetic signatures affecting the response to monoclonal antibody-based, oncologicaly targeted regimens. Different SGC histotypes demonstrate specific combinations of mutated/amplified genes that modify their clinicohistological features. In the current molecular review, we present the most important amplified oncogenes and their impact on the biological behavior of SGCS.

Phenotype and Genotype Study in a Case of Frontometaphyseal Dysplasia 1.

INTRODUCTION: Frontometaphyseal dysplasia 1 (FMD1) is a rare X-linked craniofacial syndrome belonging in the otopalatodigital spectrum of disorders. Here we present a case with severe FMD1 that was caused by a mutation in the FLNA gene located on Xq28. METHODS: A diagnosis for FMD1 was clinically set for a 22-year-old male who presented with cranial hyperostosis with marked supraorbital ridge, hypertelorism, progressive mixed hearing loss, partial anodontia, scoliosis, generalized skeletal dysplasia, and muscle atrophy. The patient's two older brothers had also severe FMD1 manifestations with generalized skeletal dysplasia, cranial hyperostosis, progressive hearing loss, and scoliosis, while their mother and maternal grandmother had some less prominent FMD1 signs. Total DNA was extracted from blood samples of the patient, his brothers, and his parents. RESULTS: DNA sequencing of all 48 exons of the FLNA gene revealed a single-point mutation (3476A>C) in exon 22. The missense mutation changes an Asp codon into an Ala codon in amino acid position 1159. The patient's two brothers had the same mutation, while their mother was a heterozygous carrier having both the mutant allele and the normal allele. CONCLUSION: The clinical diagnosis for FMD1 was confirmed by genetic analysis. It is evident that the FLNA gene product filamin A plays a critical developmental role in morphogenesis of several tissues being a cytoskeleton component, since mutations in its gene cause multiple manifestations and diverse disorders of the otopalatodigital spectrum.

Association study indicates combined effect of interleukin-10 and angiotensin-converting enzyme in basal cell carcinoma development.

Cytokines involved in inflammatory and immune response have been associated with risk for development of basal cell carcinoma (BCC). In this study, three functional DNA polymorphisms affecting gene expression were investigated in 54 BCC patients and 111 healthy controls: interleukin-1b (IL-1b) +3953C/T, interleukin-10 (IL-10) - 1082G/A and angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphisms. Significant increase of the variant alleles was observed in IL-10 - 1082G (P = 0.019) and in ACE D (P = 0.003) in BCC patients in comparison to controls. Multivariate logistic regression models evaluated the contribution of homozygous and heterozygous variant polymorphisms to the risk for BCC development. The studied polymorphisms influencing the expression of IL-10 and ACE genes were recognized as potential predictive factors for BCC. These findings suggest a possible molecular mechanism leading to BCC development that is likely to involve the activation of angiotensin receptors in combination with increased plasma levels of IL-10 in patients.

Effect of thrombosis-related gene polymorphisms upon oral cancer: a regression analysis.

It is well-known that there is an interplay between hemostasis, thrombosis and cancer. Functional DNA polymorphisms in genes encoding factors related to thrombosis have been associated with increased risk for oral squamous cell carcinoma (OSCC). The present study investigated the possible combinatory effect of 10 such polymorphisms as primary risk predictors for OSCC in a European population. Two groups including 160 patients with OSCC and 168 healthy controls of Greek and German origin were studied. The patient and control groups were comparable regarding ethnicity, age and gender. For all studied individuals, 10 genotypes of functional polymorphisms were investigated: 5,10-methylene tetrahydrofolate reductase (MTHFR) C677T, coagulation factor V (F5) Leiden, coagulation factor II (F2, also known as prothrombin) G20210A, coagulation factor XII (F12) C46T, coagulation factor XIII A1 subunit (F13A1) Val34Leu, serpine1 (SERPINE1, also known as plasminogen activator inhibitor-1) 4G/5G, protein Z (PROZ) -A13G, angiotensin I-converting enzyme (ACE) I/D, angiotensinogen (AGT) Met325Thr, and carboxypeptidase B2 (CPB2, also known as thrombin-activatable fibrinolysis inhibitor) C1040T. Multivariate logistic regression models were used in order to evaluate the relation and contribution of homozygous and heterozygous variant polymorphisms upon overall, early and advanced stages of OSCC. Five out of the studied polymorphisms, influencing the expression of SERPINE1 and ACE genes, as well as the activity of CPB2, F12 and F13 proteins, were recognized as significant predictive factors for OSCC. The 'mode of inheritance' regression model, in particular, revealed the low expression I allele of ACE to be a primary predictor in overall, early and advanced stages of oral cancer. Comparing the present findings with previous knowledge, possible interactions of these factors and their relation to the risk for OSCC development are discussed.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with decreased risk for basal cell carcinoma.

The incidence of basal cell carcinoma (BCC) is significantly reduced in individuals treated with inhibitors of angiotensin I-converting enzyme (ACE) that produces angiotensin II. The objective of this study was to investigate the possible association of a functional polymorphism in the ACE gene, which affects its transcription, with risk for BCC. In DNA samples of 92 patients with BCC and 103 healthy controls of Greek origin and comparable age and gender, we studied the ACE gene insertion/deletion (I/D) polymorphism. Fisher's exact test was used for comparison of allele and genotype frequencies between the control and patients' groups. The detected low expression I allele frequency in the group of BCC patients was significantly decreased compared to controls (15.8 vs. 31.1 %, respectively; P = 0.001). ID heterozygotes exhibited 3.06 times lower BCC risk, compared with DD homozygotes (P = 0.001; OR = 0.327, 95 % CI = 0.174-0.615). The protective role of I allele was particularly prominent in women (P = 0.007, OR = 0.299, 95 % CI = 0.125-0.716), while for men it exhibited a marginal level (P = 0.041). These findings indicate that the low expression ACE I allele carriers have a decreased risk for BCC. The protective effect of the ID genotype against BCC may be explained by a possible underlying mechanism involving the effect of produced angiotensin II levels on its receptors due to putatively different binding affinity.

Prevalence of thrombosis-related DNA polymorphisms in a healthy Greek population.

Genetic association studies have revealed a correlation between DNA variations in genes encoding factors of the haemostatic system and thrombosis-related disease. This study investigated the prevalence of 13 such genetic risk factors in a sample (N=400 alleles) of the Hellenic population of Greece. Some of these polymorphisms [coagulation factor V (F5) Leiden, coagulation factor II (F2) G20210A, 5,10-methylene tetrahydrofolate reductase (MTHFR) C677T, coagulation factor XIII A1 subunit (F13A1) Val34Leu, serpine1 (SERPINE1) 4G/5G, angiotensin I-converting enzyme (ACE) I/D, angiotensinogen (AGT) Met325Thr, integrin A2 (ITGA2) C807T] have been previously studied in Hellenic populations of Greece and Cyprus, while others such as coagulation factor XII (F12) C46T, plasma carboxypeptidase B2 (CPB2) C1040T, platelet glycoprotein Ib α polypeptide (GP1BA) VNTR, thrombomodulin (THBD) -A33G and protein Z (PROZ) - A13G have not. Most of the allelic frequencies observed are similar to those reported for other Southern European populations. Knowledge of the prevalence of these variations in a given population may assist in the design of effective preventive measures against cardiovascular disease.

A common 9 bp deletion in the ataxia-telangiectasia-mutated gene is not associated with oral cancer.

BACKGROUND: The ataxia-telangiectasia-mutated gene (ATM) product is a well-characterized tumour suppressor that plays a key role in the maintenance of genomic stability. Given the fact that the loss of heterozygosity at the ATM locus is common in head and neck tumours, we investigated the possible association of 7636del9, which is the most frequent ATM deletion, with risk for oral cancer. PATIENTS AND METHODS: The 7636del9 9nt deletion was investigated in DNA samples of 67 German and Greek patients with oral cancer and 57 healthy controls of equivalent ethnicity, age and gender, by polymerase chain reaction (PCR) followed by electrophoretic analysis. RESULTS: The anticipated deleted sequence was not detected in any of the DNA samples of oral cancer patients or controls. CONCLUSION: The findings of the present study indicated no association of the most common mutation in the ATM gene with risk for oral cancer.

Association of polymorphisms in Tumor Necrosis Factor Alpha and Beta genes with increased risk for oral cancer.

BACKGROUND: In light of the recently found contribution of inflammation-related factors to oral oncogenesis, the possible correlation of tumor necrosis factor alpha and beta genes (TNF-alpha and TNF-beta) with risk of oral cancer was investigated. MATERIALS AND METHODS: DNA samples of 160 German and Greek patients with oral squamous cell carcinoma and 153 healthy controls of equivalent age, gender and ethnicity were studied. The functional polymorphisms TNF-alpha (-308 G/A) and TNF-beta (252 G/A), which affect gene expression, were investigated by restriction fragment length polymorphism analysis. RESULTS: The frequencies of high expression A2 (-308A) TNF-alpha allele and high expression B1 (252G) TNF-beta allele were significantly increased in cancer patients compared to controls (respectively: 62.2% versus 14.7%, p<0.0001; OR 8.65, 95% CI 5.74-13.04 and 66.9% versus 15.7%, p<0.0001; OR 10.92, 95% CI 7.4-16.2). Three combined TNF-alpha/TNF-beta genotypes (A2A2/B1B1, A1A2/B1B2, A1A2/B1B1) were over-represented in cancer patients (p<0.001). No significant differences in allele frequencies were detected among most subgroups of patients divided in regard to cancer stage, family history for cancer or thrombosis, smoking or heavy alcohol consumption habits. CONCLUSION: This study showed a strong association of TNF-alpha and TNF-beta high expression alleles with increased risk of oral cancer. These findings are in accordance with previously observed high TNF-alpha levels in serum of patients with oral cancer in comparison to healthy controls.

Diabetes enhances the expression of H-ras and suppresses the expression of EGFR leading to increased cell proliferation.

EGFR kinase activity triggers numerous signaling pathways, such as the Ras/Raf/MAPK cascade, leading to the activation of various mitogen activated protein kinases, which are implicated in cell proliferation through induction of several genes, including c-fos. The possible effect of diabetes on the expression of the oncogenes EGFR, H-ras and c-fos was investigated in an experimental model of chemically induced oral oncogenesis in normal and diabetic (type I) Sprague-Dawley rats. Thirteen diabetic and twelve normal rats developed cancer after 4NQO treatment, while six diabetic and six normal animals were used as controls. The biopsies were classified pathologically (ranging from dysplasia to moderately differentiated oral squamous cell carcinoma) and were studied immunohistochemically. Several representative histological regions from each biopsy were analysed in regard to EGFR, H-ras and c-fos expression, and a comparison between normal and diabetic rats was effected. A trend of decreased EGFR expression in diabetic compared to normal rats was revealed throughout oncogenesis, which was significant in the stage of dysplasia (P<0.05). On the contrary, a trend of increased H-ras expression was observed in diabetic compared to normal rats during oncogenesis, which rose significantly in early invasion and well differentiated OSCC (P<0.001 and P<0.01 respectively). Finally, no statistical differences concerning c-fos expression were detected between diabetic and normal animals. In conclusion, it seems that diabetes reduces the expression of EGFR and initiates the Ras/Raf/MAPK signal transduction pathway by enhancing activation of other signalling molecules, such as the diabetes-associated Insulin Receptor Substrate-1, leading to increased cell proliferation without c-fos involvement.

Association of leptin -2548G/A and leptin receptor Q223R polymorphisms with increased risk for oral cancer.

PURPOSE: We investigated the possible association of DNA polymorphisms -2548G/A and Q223R in the leptin (LEP) and leptin receptor (LEPR) genes, respectively, which both affect the amount of circulating cytokine-type hormone leptin, with risk for development of oral cancer. METHODS: Polymerase chain reaction-based restriction analysis was performed in DNA samples of 150 patients with oral squamous cell carcinoma (OSCC) and 152 healthy control subjects of equivalent gender, age, and ethnicity (Greeks and Germans). RESULTS: Compared to controls, the homozygous high gene expression genotype A/A of the LEP -2548G/A polymorphism was significantly increased in the subgroups of patients with advanced cancer stages (P = 0.0001; OR 9.0, 95% CI 2.62-30.89), with a positive family history of cancer (P = 0.0346; OR 3.55, 95% CI 1.15-11.01), without tobacco abuse (P = 0.0051; OR 9.69, 95% CI 1.03-91.24), and without alcohol abuse (P = 0.0472; OR 2.16, 95% CI 0.87-5.37). The homozygous low-leptin-binding genotype G/G of the LEPR Q223R polymorphism was strongly associated with an increased risk for OSCC for all patients (P = 0.0028; OR 4.11, 95% CI 1.30-12.97) as well for most of the patient subgroups. CONCLUSIONS: The above findings are consistent with the growth-promoting role of leptin in cancer and its induction effect on angiogenesis and metastasis. This is the first study indicating the association of these LEP and LEPR gene polymorphisms with increased risk for OSCC.

H-ras and c-fos exhibit similar expression patterns during most stages of oral oncogenesis.

BACKGROUND: H-ras and c-fos oncogenes interact in signalling pathways but their level and time course of expression during oral cancer development are unclear. The present study used an animal model for the simultaneous investigation of H-Ras and c-Fos expression in sequential stages of oral oncogenesis. MATERIALS AND METHODS: Three experimental groups of Syrian golden hamsters (A, B and C; 10 animals each) and one control group (7 animals) were used. The buccal pouches of hamsters in groups A, B and C were treated with 0.5% of the carcinogen 9,10-dimethyl-1,2-benzanthracene and were excised at 10, 14 and 19 weeks, respectively. The biopsies, which included tissue stages ranging from normal oral mucosa to moderately differentiated carcinoma, were studied immunohistochemically. RESULTS: A reduction in both H-Ras and c-Fos expression was observed from group A to B and from hyperplasias to early tumour stages, while a simultaneous increase was noted from group B to C and from well-differentiated to moderately-differentiated carcinomas. The H-ras/c-fos expression ratio had a value of approximately (1.09 +/- 0.21) in five out of seven studied tissue stages. CONCLUSION: H-Ras and c-Fos exhibit a similar expression pattern throughout most stages of oral carcinogenesis, an observation supported by the known molecular pathway connecting H-ras signalling with subsequent c-fos gene transcription.

Angiotensinogen polymorphism is associated with risk for malignancy but not for oral cancer.

BACKGROUND: In light of the recently found contribution of angiogenic and inflammation-related factors to malignancies, this study investigated the possible association of the angiotensinogen gene (AGT) with increased risk of oral cancer. MATERIALS AND METHODS: The M235T polymorphism, which influences AGT gene expression, was evaluated by restriction fragment length polymorphism analysis in the DNA samples of 163 German and Greek patients with oral squamous cell carcinoma (OSCC) and 124 healthy controls of equivalent gender, ethnicity and age. RESULTS: No significant difference of the mutant (235T) allele, which results in higher AGT gene expression, was observed in the whole patient group in comparison with the normal controls. Similarly, compared to the controls no significant difference of either allele or carrier frequency was detected in almost every subgroup of patients. Only in the subgroup of patients with a positive family history of cancer was a significant increase of mutant T allele and carrier frequencies observed, compared to the controls (50% vs. 36.7% and 79.3% vs. 61.3%, respectively, p < 0.05 in both cases). In this particular subgroup of patients the odds ratio for OSCC of TT homozygotes was 3.57 (CI 95% 1.2-10.62), while for the MT heterozygotes it was 2.41 (CI 95% 1.06-5.49). CONCLUSION: This study did not reveal an association of the AGT M235T polymorphism with oral oncogenesis, but certainly suggested a possible association of this specific polymorphism with other types of cancer. The present findings support a previous suggestion that the pathway of oral oncogenesis is probably based on angiotensin-converting enzyme and bradykinin interaction and not on AGT and angiotensin peptides.

A DNA polymorphism of stromal-derived factor-1 is associated with advanced stages of oral cancer.

BACKGROUND: Stromal derived factor-1 (SDF-1), a protein related to angiogenesis and inflammation, has been correlated with the progression of a number of malignancies, but not with oral squamous cell carcinoma. In light of the known contribution to the development of oral cancer of other gene polymorphisms for proteins responsible for angiogenesis, inflammation and thrombosis, this study investigated whether the G801A polymorphism in the SDF-1 gene is associated with this malignancy. PATIENTS AND METHODS: The G801A polymorphism was examined by restriction fragment length polymorphism analysis in DNA samples from 159 patients with oral squamous cell carcinoma and 101 matched healthy controls. RESULTS: The detected allele frequency of the "high production related" A allele in the control group was 25.3%. There was a slight decrease in allele frequency in patients (18.6%), but it was not statistically significant. The same pattern was observed in subgroups of patients in regard to smoking habits and family history of cancer or thrombosis. Interestingly, in comparison to controls, the A allele frequency was significantly lower in patients with advanced cancer stages III and IV (12.5%, p=0.005) and in patients with alcohol abuse (12.5%, p=0.02). CONCLUSION: The G801A polymorphism of the SDF-1 gene is associated with advanced stages of oral cancer, especially in alcohol abusers.

The interleukin-10 (-1082A/G) polymorphism is strongly associated with increased risk for oral squamous cell carcinoma.

BACKGROUND: Increased levels of interleukin-10 (IL-10) have been observed in patients with oral cancer, possibly as a result of suppression of the immune response. Based on this, the -1082A/G polymorphism, which influences IL-10 gene expression level, was investigated in regard to its possible association with risk for oral cancer. PATIENTS AND METHODS: The polymorphism was examined in DNA samples of 144 patients with oral squamous cell carcinoma and 141 healthy controls of equivalent gender, age and ethnicity. RESULTS: The detected allele frequencies for the high expression G allele were significantly higher in patients compared to controls (34.7% versus 21.3%, respectively, p=0.0004), as well as in patients that were smokers but not those that were heavy alcohol consumers. This highly significant difference in G allele frequency was mainly due to the increase of AG heterozygotes in patients compared to controls (OR 3.05, 95% CI 1.84-5.05). CONCLUSION: These findings suggest that the high expression G allele of the -1082A/G polymorphism of the inflammation and angiogenesis-related IL-10 is strongly associated with increased risk for oral cancer.

Gene expression polymorphisms of interleukins-1 beta, -4, -6, -8, -10, and tumor necrosis factors-alpha, -beta: regression analysis of their effect upon oral squamous cell carcinoma.

PURPOSE: Functional DNA polymorphisms affecting gene expression and serum or saliva levels of interleukins IL-1 beta,-4,-6,-8,-10 and tumor necrosis factors TNF-alpha,-beta have been associated with increased risk for the development of oral squamous cell carcinoma (OSCC). The present retrospective case-control study examines possible interactions between seven cytokine genotype polymorphisms and their combinatory effect in predicting the occurrence of OSCC in Caucasians. METHODS: Three hundred and thirty Greeks and Germans were studied, consisting of 162 OSCC cases and 168 healthy controls of comparable age, gender, and ethnicity. A series of multivariate logistic regression models, adjusted for age and gender, was constructed in order to assess the contribution of homozygous or heterozygous variant genotypes of polymorphisms IL-1 beta (+3953C/T), IL-4 (-590C/T), IL-6 (-174G/C), IL-8 (-251A/T), IL-10 (-1082A/G), TNF-alpha (-308G/A) and TNF-beta (+252G/A) upon overall, early and advanced stages of OSCC development. RESULTS: The contribution of TNF-alpha and IL-6 was consistent and robust in almost all models constructed. Furthermore, when the mode of inheritance of each variant allele was taken into account in a "biological" multivariate logistic regression model, four polymorphisms emerged as primary predictors for overall stages of OSCC: TNF-alpha (OR = 15.27; 95% CI = 7.30-31.96), IL-6 (OR = 8.33; 95% CI = 3.95-17.58), IL-8 (OR = 3.54; 95% CI = 1.69-7.43) and IL-10 (OR = 2.65; 95% CI = 1.28-5.46). Finally, IL-1 beta, IL-4 and TNF-beta polymorphisms were not primary predictors of OSCC development in all constructed models. CONCLUSIONS: This study revealed the highly significant contributions of two out of seven studied cytokines (IL-6 and TNF-alpha) in the occurrence of OSCC. Based on these findings and previous reports, possible stoichiometrical interactions of cytokines leading to OSCC development are discussed.

Increased risk for oral cancer is associated with coagulation factor XIII but not with factor XII.

In light of recently found contribution of factors associated with thrombosis and inflammation to carcinogenesis, we investigated the possible association of coagulation factors XII and XIII with increased risk for oral cancer. In DNA samples of patients with oral squamous cell carcinoma and healthy controls of comparable ethnicity, age and sex, we studied the C46T polymorphism in FXII gene which affects gene transcription and the V34L polymorphism in FXIII gene which affects enzyme activity resulting in alteration of the fibrin network structure. No significant differences were observed in genotype and mutant allele frequencies of the FXII C46T polymorphism between patients and healthy controls. On the contrary, the obtained data for FXIII V34L polymorphism revealed a significant frequency increase of the L allele, which results in thinner fibrin network, in the whole group of patients compared to controls (33.1 versus 22.2% respectively, Fischer value P=0.006). In addition, LL homozygotes had a 3-fold greater risk for developing oral cancer (OR 2.893, 95% CI 1.056-7.890), while in VL heterozygotes a 2-fold greater risk was observed (OR 1.868, 95% CI 1.126-3.101). Significantly increased frequency of L allele was also observed in sub-groups of patients without family history of thrombophilia or cancer, with and without tobacco abuse and with alcohol abuse (P<0.05). Interestingly, in comparison to controls only patients with early cancer stages I and II had significantly increased L alleles and not patients with advanced stages III and IV. These findings suggest that the presence of L allele is strongly associated with oral cancer generation but not with its progression and metastasis. In the presence of L allele, the fibrin network is composed of thinner fibers, is less porous and facilitates tumor stroma formation and therefore tumor cell proliferation. Nevertheless, this thinner and less porous fibrin network inhibits cell migration.

Expression of cell cycle regulator p16 is not affected by diabetes during oral oncogenesis.

BACKGROUND: The tumor suppressor protein p16 plays a vital role in the regulation of the cell cycle. The expression of p16 was investigated in an experimental model of chemically induced carcinogenesis in normal and diabetic (type I) Sprague-Dawley rats. MATERIALS AND METHODS: Tissue sections ranging from normal oral mucosa to moderately differentiated oral squamous cell carcinoma (OSCC) were studied immunohistochemically. RESULTS: In normal rats p16 expression increased gradually during oral oncogenesis, but a significant increase was observed only in moderately differentiated OSCC (p=0.038). On the contrary, in diabetic rats the detected gradual increase was significant in hyperplasia, dysplasia, early invasion and well-differentiated OSCC (p<0.001). Nevertheless, there was no significant difference in p16 expression during oral oncogenesis between normal and diabetic animals. CONCLUSION: It seems that the expression of cell cycle regulator p16 is not affected by diabetes in the studied animal model of oral oncogenesis.

EGFR and c-Jun exhibit the same pattern of expression and increase gradually during the progress of oral oncogenesis.

BACKGROUND: Epidermal growth factor receptor (EGFR) and c-Jun oncogenes are implicated in the same pathway of signal transduction affecting cell differentiation. In order to investigate their possible correlation with sequential histological stages of OSCC formation, we established an experimental model of induced oral carcinogenesis in Syrian golden hamsters. MATERIALS AND METHODS: Thirty-seven animals were divided into one control group (n=7) and three experimental groups (n = 10 each), which were treated with a carcinogen and sacrificed at 10, 14 and 19 weeks after treatment. Tumour sections were studied using monoclonal antibodies against EGFR and c-Jun proteins. RESULTS: The same pattern of expression was observed for both oncogenes, with a significant gradual increase of positively stained cells throughout oral carcinogenesis. CONCLUSION: Since EGFR and c-Jun are implicated in the same molecular pathway of signal transduction, it may be assumed that an increase in EGFR levels leads to increased activation of phospholipase Cy signal transduction cascade, which in turn activates c-Jun protein. Therefore, c-Jun expression in oral cancer seems to be increased through the EGFR-PLCy-Raf-MEK-ERK pathway and not the H-ras-Raf-MEK-ERK/JNK pathway.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with increased risk for oral cancer.

INTRODUCTION: In light to recently found contribution of factors associated with thrombosis and inflammation to carcinogenesis, we investigated the possible association of angiotensin I- converting enzyme (ACE) with increased risk for oral cancer. MATERIALS AND METHODS: In DNA samples of 160 patients with oral squamous cell carcinoma and 153 healthy controls of comparable ethnicity, age and sex, we studied the insertion/deletion (I/D) polymorphism in the ACE gene, which affects its transcription. RESULTS: The I allele frequencies were significantly increased in patients compared to controls, 40.6% versus 27.5% (p < 0.001), respectively. The II homozygotes had a three-fold greater risk for developing oral cancer (odds ratio 3.17, 95% C.I. 1.32-7.61). A significant increase of I alleles was observed in patients regardless their smoking or alcohol consumption habits, early or advanced stage of cancer, presence or absence of a family history for cancer or thrombophilia (Fischer values p < 0.05). DISCUSSION: These findings suggest that the I/D polymorphism, by affecting the ACE gene expression, is associated with the progress of oral oncogenesis.