Carcinogenesis Of Oral Squamous Cell Carcinoma Research Articles

Overexpression of HDAC9 promotes oral squamous cell carcinoma growth, regulates cell cycle progression, and inhibits apoptosis.

Histone deacetylases (HDACs) are a family of deacetylase enzymes that regulate the acetylation state of histones and a variety of other non-histone proteins including key oncogenic and tumor suppressor proteins, which modulates chromatin conformation, leading to regulation of gene expression. HDACs has been grouped into classes I-IV and histone deacetylase 9 (HDAC9) belongs to class IIa which exhibits tissue-specific expression. Recent reports have demonstrated both pro-oncogenic and tumor suppressive role for HDAC9 in different cancers; however, its role in OSCC remains elusive. Here, we investigated the role of HDAC9 in pathogenesis of oral squamous cell carcinoma (OSCC). Our data showed significantly increased mRNA and protein expression of HDAC9 in clinical OSCC samples and UPCI-SCC-116 cells as compared to normal counterpart. Kaplan-Meier analysis showed that the patients with high-level of HDAC9 expression had significantly reduced overall survival than those with low-level of HDAC9 expression (p=0.034). Knockdown of HDAC9 using siRNA interference suppressed cell proliferation, increased apoptosis, and induced G0/G1 cell cycle arrest in UPCI-SCC-116 cells. Immunofluorescence analysis showed increased nuclear localization of HDAC9 in frozen OSCC sections, and indicative of active HDAC9 that may transcriptionally repress its downstream target genes. Subsequent investigation revealed that overexpression of HDAC9 contributes to OSCC carcinogenesis via targeting a transcription factor, MEF2D, and NR4A1/Nur77, a pro-apoptotic MEF2 target.

Role of Hypoxia Inducible Factor-1α messenger RNA expression in malignant transformation of oral submucous fibrosis

Background:Oral submucous fibrosis (OSF) is an oral potentially malignant disorder depicting extensive fibrosis of the submucosa affecting most parts of the oral cavity, including pharynx and upper third of the oesophagus. Despite its high potentially malignant nature, transformation of the epithelium towards malignancy in the background of fibrosis has not been studied extensively till date. Hypoxia Inducible Factor-1α (HIF-1α) is a master transcription factor that is induced by hypoxia and has found to be significantly associated with both fibrosis and malignancy.Aim:To test the hypothesis of differential expression of HIF-1α in malignant transformation of OSF.Materials and methods:Fifteen samples each of Normal Mucosa (NOM), OSF and Oral Squamous Cell Carcinoma (OSCC) making total of 45 tissues were studied by formalin fixed Haematoxylin and Eosin (H&E)-stained sections and frozen fixed for Reverse Transcription Polymerase Chain Reaction (RT-PCR). The relationship between differential HIF-1α messenger RNA expression level and oral epithelial dysplasia, inter incisal opening and grade of OSCC was studied.Conclusions:An upregulation of HIF-1α expression level is positively correlated with oral carcinogenesis and grade of OSCC, whereas downregulation is associated with fibrosis. Hence, it can be used as both diagnostic as well as a prognostic marker.

Targeting thiamine-dependent enzymes for metabolic therapies in oral squamous cell carcinoma?

Thiamine-dependent enzymes (TDEs) linking glycolysis with the tricarboxylic acid cycle (TCA) pyruvate dehydrogenase (PDH), of the pentose phosphate pathway transketolases (TKTs), the TCA alpha-ketoglutarate deydrogenase (KGDH)/2-oxoglutarate dehydrogenase (OGDH) complex, and the amino acid catabolism branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex are crucial factors for tumor metabolism. The expression of these enzymes has not been analyzed for carcinogenesis of oral squamous cell carcinoma (OSCC) with special focus on new targeted metabolic therapies as yet. TDEs PDH, KGDH (OGDH), and BCKDH were analyzed in normal oral mucosa (n = 14), oral precursor lesions (simple hyperplasia, n = 21; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 46) by immunohistochemistry and western blot (WB) analysis in OSCC tumor cell lines. Although the total numbers of PDH and KGDH (OGDH) positive samples decreased in OSCC, both enzymes were significantly overexpressed in the carcinogenesis of OSCC compared with normal tissue. BCKDH has been demonstrated to be significantly overexpressed in the carcinogenesis of OSCC. Specificity of the antibodies was confirmed by WB analysis. This is the first study showing increased expression of TDEs in OSCC. Metabolic targeting of TDEs (including TKTs) by antagonistic compounds like oxythiamine or oxybenfothiamine may be a useful strategy to sensitize cancer cells to common OSCC cancer therapies.

The role of miR‐450a in oral squamous cell carcinoma carcinogenesis

microRNAs in tumor progression are crucial in head & neck cancer. Our research group found that miR‐450a were significantly higher in 46 clinical OSCC specimens than those in corresponding adjacent non‐cancerous specimens (p<0.001). However, its role in oral carcinoma has not been elucidated yet. miR‐450a is highly conserved among mammals. In homo sapiens, duplicated miR‐450a were located at adjacent loci in X chromosome. Gene expression microarray was performed to identify potential miR‐450a mediating genes. Differential gene expressions in pre‐miR‐450a‐transfected DOK and SCC15 were analyzed. Using Gene Set Enrichment Analysis, 16878 & 17000 down‐regulated genes were clarified in DOK & SCC15, respectively. To narrow down these miR‐450a targeting genes, two gene lists were independently overlapped with target predicted program microRNA.org. These two gene lists were further reduced to 419 genes in DOK & 465 genes in SCC15, and 256 genes were common in both two gene sets. We used RT‐PCR to validate a suspected membrane protein, TMEM182. The expression of TMEM182 was down‐regulated in RNA and protein levels. We verified that this TMEM182 down‐regulation was under a post‐translational level mediated by miR‐450a. Up‐regulation of miR‐450a in OSCC would enhance cell detachment ability. But, the cell proliferation was higher in miR‐450a overexpressed cells. We suggested that miR‐450a regulates cell adhesion through down‐regulation of TMEM182, and further influences cell migration in oral cancer.

Glutaminolysis and carcinogenesis of oral squamous cell carcinoma.

Glutaminolysis is a crucial factor for tumor metabolism in the carcinogenesis of several tumors but has not been clarified for oral squamous cell carcinoma (OSCC) yet. Expression of glutaminolysis-related solute carrier family 1, member 5 (SLC1A5)/neutral amino acid transporter (ASCT2), glutaminase (GLS), and glutamate dehydrogenase (GLDH) was analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry. SLC1A5/ASCT2 and GLS were significantly overexpressed in the carcinogenesis of OSCC compared with normal tissue, while GLDH was weakly detected. Compared with SIN I-III SLC1A5/ASCT2 and GLS expression were significantly increased in OSCC. GLDH expression did not significantly differ from SIN I-III compared with OSCC. This study shows the first evidence of glutaminolysis-related SLC1A5/ASCT2, GLS, and GLDH expression in OSCC. The very weak GLDH expression indicates that glutamine metabolism is rather related to nucleotide or protein/hexosamine biosynthesis or to the function as an antioxidant (glutathione) than to energy production or generation of lactate through entering the tricarboxylic acid cycle. Overcoming glutaminolysis by targeting c-Myc oncogene (e.g. by natural compounds) and thereby cross-activation of mammalian target of rapamycin complex 1 or SLC1A5/ASCT2, GLS inhibitors may be a useful strategy to sensitize cancer cells to common OSCC cancer therapies.

Overexpression of c-fos promotes cell invasion and migration via CD44 pathway in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is one of the most deadly malignant tumors with high invasive potential and frequently cervical lymph node metastasis. AP-1 plays a critical role in tumor invasion and metastasis, but there are few reports on the role of c-Fos in OSCC carcinogenesis and metastasis. Investigate c-Fos expression in clinical samples from 58 primary patients with OSCC by immunohistochemistry. c-Fos knockdown stable cell lines were established by lentiviral infection and transwell cell invasion assay to detect the effects of c-Fos knockdown on tumor cell invasion. Nuclear and cytoplasmic c-Fos protein were both overexpression in cancerous tissues compared with adjacent non-malignant epithelia (nuclear: P < 0.001, cytoplasmic: P = 0.005). Higher level nuclear c-Fos expression was found in the tumor samples of patients with lymph node metastasis than those without lymph node metastasis (4.85 ± 1.43 vs. 3.61 ± 1.28, P = 0.002). Higher level of c-Fos expression was also found in tumor invasive front margin than tumor center and high nuclear expression of c-Fos indicated poor survival. Knockdown of c-Fos greatly suppressed tumor cell proliferation and invasion and downregulated CD44 and CyclinD1 expression in HN6 and SCC9 cells. However, CyclinD3, c-myc, and Erk1/2 were found no changes to c-Fos depletion. c-Fos promoted cell invasion and migration via CD44 pathway in OSCC. c-Fos could be used as a potential therapeutic target gene and an additional marker for evaluation of lymph node metastasis.

Apoptosis resistance-related ABCB5 and DNaseX (Apo10) expression in oral carcinogenesis

Background. Apoptosis resistance is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC). Methods. Expression of apoptosis resistance-related ATP-binding cassette (ABC) transporter ABCB5 [subfamily B (MDR/TAP) member 5] and DNaseX (Apo10) were analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I–III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry. Results. Expression of ABCB5 and Apo10 were significantly increased in the carcinogenesis of OSCC compared with normal tissue. Compared with SIN I–III, ABCB5 expression was significantly decreased in OSCC. Apo10 expression did not significantly differ from OSCC compared with SIN I–III. Conclusions. This study provides the first evidence of the expression of ABCB5 and Apo10 in the multi-step carcinogenesis of OSCC. Overcoming drug resistance of ABCB5+ and Apo10+ cells in precursor lesions and tumors by natural compounds may act as sensitizers for apoptosis or could be useful for chemoprevention.

EGF up-regulates miR-31 through the C/EBPβ signal cascade in oral carcinoma.

Oral squamous cell carcinoma (OSCC) is one of the most prevalent carcinomas worldwide. MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression and modulate physiological or pathological processes including OSCC carcinogenesis. miR-31 has been found to be up-regulated in OSCC and to act as an oncogenic miRNA. However, the molecular mechanism underlying miR-31 up-regulation in OSCC is still obscure. The activation of epidermal growth factor receptor (EGFR) signaling axis plays key roles in driving oral carcinogenesis. Our screening identified that there is up-regulation of miR-31, miR-181b and miR-222 in OSCC cells following EGF treatment. Subsequent analysis showed that EGF treatment led to AKT activation, which then resulted in miR-31 up-regulation. Moreover, EGF treatment and the AKT activation induced by exogenous expression up-regulated C/EBPβ expression. The miR-31 up-regulation induced by EGF was abrogated by AKT inhibition or by the knockdown of C/EBPβ expression. In OSCC cell subclones stably overexpressing the functional isoform of C/EBPβ, miR-31 expression was up-regulated. Curcumin is a natural ingredient exhibiting anti-cancer potential. It was found that curcumin attenuated AKT activation and the up-regulation of C/EBPβ and miR-31 caused by EGF stimulation in OSCC cells. Lastly, concordance across the expression of EGFR, the expression of C/EBPβ and the expression of miR-31 in OSCC tissues was found. This study describes a novel scenario where the up-regulation of miR-31 expression in OSCC is, at least in part, a consequence of EGFR oncogenic activation. Although the AKT activation and C/EBPβ expression after EGF treatment might not be directly linked, both events are the crucial mediators underlying miR-31 up-regulation in the EGFR signaling axis.

Update of molecular pathobiology in oral cancer: a review

Head and neck cancer including oral squamous cell carcinoma (OSCC) is the sixth most common cancer in the world. OSCC has a high potential for local invasion and nodal metastasis, and the overall 5-year survival rate has not significantly changed during the past 30 years. Recent research has elucidated the detailed molecular mechanisms of carcinogenesis, tumor progression, and metastasis of OSCC. It is generally accepted that OSCC arises from multiple genetic alterations caused by chronic exposure to carcinogens such as alcohol, smoking, viral infections, and inflammation. The molecular mechanisms of carcinogenesis, tumor progression, and metastasis of head and neck cancer have been elucidated by recent advances in molecular biology. However, many unsolved questions remain. In this review, we describe the current molecular biological findings such as human papillomavirus infection, epithelial-mesenchymal transition, microRNA, and our novel molecular pathological findings of OSCC.

Id1 and NF-κB promote the generation of CD133+ and BMI-1+ keratinocytes and the growth of xenograft tumors in mice

Id1 and NF-κB are highly expressed in oral squamous cell carcinoma (OSCC). Whether they have a synergistic role in the carcinogenesis of OSCC is unclear. The current study was designed to demonstrate the synergy of both Id1 and NF-κB in the underlying disease mechanisms of OSCC using in vitro and in vivo animal models. Id1 and NF-κB strengthened the expression of both CD133 and BMI-1 in OSCC cell cultures. CD133+ and BMI-1+ keratinocytes from OSCC tissues and cell cultures initiated the growth of xenograft tumors in SCID/Beige mice. Id1 and NF-κB regulate the expression of CD133 and BMI-1 in an additive or synergistic manner in OSCC, which is associated with the generation of naïve and self-renewable keratinocytes and initiate the growth of xenograft tumors in vivo.

Potentially malignant disorders of the oral cavity: Current practice and future directions in the clinic and laboratory

Despite commendable progress in the prevention, detection, and treatment of a wide variety of solid tumor types, oral squamous cell carcinoma (OSCC) remains a significant health burden across the globe. OSCC carcinogenesis involves accumulation of genetic alterations that coincide with the multistep malignant transformation of normal oral epithelium. OSCC is often first diagnosed at late stages of the disease (advanced regional disease and/or metastasis). Delayed diagnosis precludes successful treatment and favorable outcomes. In clinical practice, opportunities exist to identify patients with oral potentially malignant disorders (OPMDs), which precede the development of cancer. This review addresses the current status of laboratory and clinical research on OPMDs, with emphasis on leukoplakia and erythroplakia. OSF is also presented, though there is a paucity of published studies on this disorder. We focus on findings that could translate into earlier diagnosis and more efficacious treatment of those lesions with significant malignant potential. We explore how markers of OPMD malignant transformation might be implemented into current diagnostic practice to help clinicians objectively stratify patients into treatment/follow-up groups according to relative risk. We provide an overview of recently concluded and ongoing OPMD chemoprevention trials. We describe laboratory OPMD models that can be used to not only to reveal the genetic and molecular intricacies of oral cancer but also to develop novel screening methods and therapeutic approaches. Finally, we call for targeted screening programs of at-risk populations in order to facilitate diagnosis and treatment of OPMD and early OSCC.

Clinical and histopathological evidence of oral squamous cell carcinoma in young patients: systematized review

The oral squamous cell carcinoma (OSCC) very often affects subjects above the sixth decade of life. However an increasing incidence has been observed in younger individuals, below 40 years. We conducted a systematized review of the current clinical, histopathological and therapeutic aspects of OSCC in young patients. Our work included studies that addressed OSCC involving young patients in the period 2007 2012, and which were indexed in PubMed. Initially, 499 articles were obtained; after refinement, 340 articles had their titles and abstracts evaluated, with 17 included in the sample. The majority of studies reported male predominance (87.5%), association with tobacco and/ or alcohol use (66.6%), advanced clinical stages at diagnosis (77.7%) and, at histopathology, moderately differentiated tumors (72.7%). Based on the results, we believe there are differences in the factors associated with pathogenesis, biological behavior and prognosis in young patients, since most studies show more rapid and aggressive tumor progression in this age group. We suggest the conduction of research focusing on the pathogenesis and carcinogenesis of OSCC in young patients, thereby searching for better scientific evidence.

Role of EZH2 in oral squamous cell carcinoma carcinogenesis

Oral squamous cell carcinoma (OSCC) is a common human malignancy with high incidence rate and poor prognosis. Although the polycomb group protein enhancer of zeste homolog 2 (EZH2) plays a crucial role in cell proliferation and differentiation during the occurrence and development progress of several kinds of malignant tumors, the impact of EZH2 on the development and progression of OSCC is unclear. In this study, we demonstrate that EZH2 is overexpressed in OSCC cells and clinical tissue. With in vitro RNAi analysis, we generated stable EZH2 knocking down cell lines from two OSCC cell lines, with two sh-RNAs targeting to EZH2, respectively. We found that knocking down of EZH2 could decrease the proliferation ability and induce apoptosis of OSCC cells. Moreover, we demonstrated that of EZH2 inhibition decreased the migration and metastasis of OSCC cells. In conclusion, the results of the current study demonstrated an association between EZH2 expression and OSCC cell development. We recommend that EZH2 acts as an oncogene and plays an important role in OSCC carcinogenesis.

Association of cancer metabolism-related proteins with oral carcinogenesis - indications for chemoprevention and metabolic sensitizing of oral squamous cell carcinoma?

BackgroundTumor metabolism is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC).MethodsExpression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, PFK-1, LDHA, TKTL1), mitochondrial enzymes (SDHA, SDHB, ATP synthase) were analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry and real-time polymerase chain reaction (qPCR) analysis in OSCC cell lines. Metabolism-related proteins were correlated with proliferation activity (Ki-67) and apoptotic properties (TUNEL assay) in OSCC. Specificity of antibodies was confirmed by western blotting in cancer cell lines.ResultsExpression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, LDHA, TKTL1), and mitochondrial enzymes (SDHA, SDHB, ATP synthase) were significantly increased in the carcinogenesis of OSCC. Metabolic active regions of OSCC were strongly correlated with proliferating cancer (Ki-67+) cells without detection of apoptosis (TUNEL assay).ConclusionsThis study provides the first evidence of the expression of IGF-R1, glycolysis-related proteins GLUT-1, HK 2, PFK-1, LDHA, and TKTL1, as well as mitochondrial enzymes SDHA, SDHB, and ATP synthase in the multi-step carcinogenesis of OSCC. Both, hypoxia-related glucose metabolism and mitochondrial oxidative phosphorylation characteristics are associated with the carcinogenesis of OSCC. Acidosis and OXPHOS may drive a metabolic shift towards the pentose phosphate pathway (PPP). Therefore, inhibition of the PPP, glycolysis, and targeted anti-mitochondrial therapies (ROS generation) by natural compounds or synthetic vitamin derivatives may act as sensitizer for apoptosis in cancer cells mediated by adjuvant therapies in OSCC.

Association of Ki-67 antigen and p53 protein at invasive tumor front of oral squamous cell carcinoma.

Studies reveal that invasive tumor front may be the best field for quantification of proliferative and apoptotic markers. The current study assessed the expression of Ki-67 antigen and p53 protein at invasive tumor front of oral squamous cell carcinoma (OSCC) and correlated the immunostaining with the histologic grades of malignancy. A total of 80 slides sample was prepared for the study, one each from ten normal oral mucosa cases and two each from 30 OSCC cases. The OSCC patients were biopsied along invasive tumor front, and samples were immunohistochemically analyzed for the expression of both Ki-67 antigen and p53 protein. Of the total 30 OSCC cases, the expression of p53 was found positive in 20 cases (66.6%), while Ki-67 expression was found positive in 21 cases (70%). All the cases in the control group were negative. A higher p53 and Ki-67 expression were seen in OSCC group as compared to normal mucosa. On comparing the control group with various grades of OSCC a statistically significant result was obtained. Higher and statistically significant expression was noted for both p53 and Ki-67 antigen. The results emphasize the potential of Ki-67 and p53 as biomarkers of carcinogenesis in OSCC. Ki-67 expression was comparatively higher when compared with p53 except in poorly differentiated squamous cell carcinoma and signifies actively proliferating malignant cells at invasive tumor front.

Clinical Significance of Keap1 and Nrf2 in Oral Squamous Cell Carcinoma

Oxidative stress has been reported to play an important role in progression and prognostication in various kinds of cancers. However, the role and clinical significance of oxidative stress markers Keap1 and Nrf2 in oral squamous cell carcinoma (OSCC) has not been elucidated. This study aimed to investigate the correlation of oxidative stress markers Keap1 and Nrf2 expression and pathological features in OSCC by using tissue microarray. Tissue microarrays containing 17 normal oral mucosa, 7 oral epithelial dysplasia and 43 OSCC specimens were studied by immunohistochemistry. The association among these proteins and pathological features were analyzed. Expression of oxidative stress markers Keap1, Nrf2, and antioxidants PPIA, Prdx6, as well as CD147 was found to increase consecutively from normal oral mucosa to OSCC, and the Keap1, Nrf2, PPIA, Prdx6, CD147 expression in OSCC were significantly higher when compared to normal oral mucosa. Expression of Keap1, Nrf2 in tumors was not found to be significantly associated with T category, lymph node metastases, and pathological grade. Furthermore, we checked the relationship among these oxidative stress markers and found that Keap1 was significantly correlated with Nrf2, Prdx6 and CD147. Significant relationship between Nrf2 and Prdx6 was also detected. Finally, we found patients with overexpression of Keap1 and Nrf2 had not significantly worse overall survival by Kaplan–Meier analysis. These findings suggest that ROS markers are associated with carcinogenesis and progression of OSCC, which may have prognostic value and could be regarded as potential therapeutic targets in OSCC.

PP106: Association between human papillomavirus and oral squamous cell carcinoma in young Japanese patients

Background This study aimed to examine the association between human papillomavirus (HPV) and molecular markers in young patients with oral squamous cell carcinoma (SCC). Methods From the cohort of patients enrolled for the treatment of oral SCC in our department during 2001–2009, we identified 40 cases with adequate formaldehyde-fixed paraffin-embedded (FFPE) samples. The median age at diagnosis was 32 years (the range was 21–38 years). Diagnostic procedures were studied on FFPE specimens. The HPV test was performed using a Roche-AMPLICOR® Human Papillomavirus detection kit. Immunohistochemical (IHC) staining was tested for detection of the p16, p53 and Fas-associated death domain containing protein (FADD). The correlation between IHC staining, HPV status, and outcome was analyzed. Results HPV was detected in 2 out of 40 patients (5%), whereas p16 overexpression was observed in 13 cases (32.5%). Overexpressions of p53 and FADD were found in 13 cases (32.5%) and 17 cases (42.5%), respectively. There was negative correlation between the overexpression of p16 and tumour differentiation (Pearson’s correlation r = −0.413; p = 0.008). We also detected positive correlation between the overexpression of p53 and FADD (Pearson’s correlation r = 0.483; p = 0.002). However, there was no marked association between the p16 expression and HPV status. Furthermore, molecular markers were not found to be relevant in assessing clinical outcome. Conclusion The expression of p16 is not an appropriate surrogate marker for HPV infection in oral SCC, and it is unlikely that HPV infection plays an important role in carcinogenesis of oral SCC in young Japanese patients.

Progressive Extracellular Matrix Disorganization in Chemically Induced Murine Oral Squamous Cell Carcinoma

Introduction. Oral squamous cell carcinoma (OSCC) is one of the ten most common cancers affecting the human population. Tumor pathogenesis implies a multistep process in which cells acquire features that enable them to become tumorigenic and ultimately malignant. The process of OSCC carcinogenesis can be reproduced in animal models, the OSCC induction with 4-nitroquinoline-1-oxide (4NQO) in mice is a widely used tool for studying tumor pathogenesis. Objective. The aim of the present study was to determine the progressive changes in basal lamina and connective tissue remodeling during 4NQO-induced OSCC carcinogenesis. Material and Methods. Samples were classified according to “International Histological Classification of tumors” in mild, moderate, and severe dysplasia and invasive carcinoma. Five samples of each pathologic entity and control healthy tongues were used. Immunohistochemical analysis of collagen IV as well as histochemical analysis of glycosylated molecules (PAS) and collagen I (Picro Sirius red) were performed. Results. During experimental-induced carcinogenesis by 4NQO a progressive basal lamina destruction and collagen I disorganization in adjacent connective tissue can be observed. Conclusion. Our results confirm previous studies that show alterations in extracellular matrix (ECM) in malignant lesions, validating the experimental carcinogenesis induced by 4NQO.

Retinoblastoma and p53 protein expression in pre-malignant oral lesions and oral squamous cell carcinoma

The retinoblastoma (Rb) and p53 genes play a fundamental role in cell cycle mechanisms, and their deregulation is related to many steps of oral cancer carcinogenesis. This study was conducted to evaluate the expression of the p53 and Rb proteins in malignant and pre-malignant oral cavity lesions. This retrospective study was conducted at the Federal University of Bahia, Salvador, Brazil, and the Molecular Biology Laboratory of the Otorhinolaryngology Department at the University of Heidelberg, Heidelberg, Germany. Excisional biopsy samples of oral cavities were collected from patients with suspected oral lesions. The samples were processed by immunohistochemistry to be classified by a semi-quantitative score: samples with a ≤ 10% positivity were considered to have weak/negative expression (-); those with 11-50% positivity, moderate expression (+); and those with >50% positivity, high expression (++). Seventy-one patients were studied (75% male; median age, 52 years; range, 24-84). Of the samples studied, 59.4% were oral squamous cell carcinoma (OSCC) and 40.6% were pre-neoplastic lesions (leukoplakia and actinic cheilitis). OSCC presented higher expression of Rb protein compared to pre-malignant lesions: 75 vs. 25% (p<0.001). Pre-neoplastic lesions presented higher expression of p53 protein compared to OSCC lesions: 55.2 vs. 44.8% (p = 0.030). Despite the small number of samples, the expression of these cell cycle biomarkers (p53 and Rb protein) in excisional biopsies suggests that molecular lesion assessment can determine pre-malignant lesions, and that its use may improve the clinical and surgical treatment of early lesions. Thus, p53 protein expression may be related to the early steps of carcinogenesis in OSCC. Finally, a higher Rb expression was also observed in malignant lesions.

English

This study is about proteomic analysis of oral verrucous carcinoma (OVC). The total proteins obtained from tumour and adjacent normal oral mucosa of patients with OVC and oral squamous cell carcinoma (OSCC) were separated with two dimensional electrophoresis (2-DE) by using immobilized pH gradient strips and visualized by staining with silver nitrate. The gel images were acquired by scanner and 2-DE analysed by image master 2D elite. Twenty distinct protein spots were excised from gel randomly and digested in gel by TPCK-trypsin. Mass analysis of the tryptic digested peptides mixture was performed by using MALDI-TOF-MS. Peptide mass fingerprints (PMFs) obtained by the MALDI-TOF analysis were applied to National Center for Biotechnology Information (NCBI), SWISS-PROT and MSDB databases using Mascot software. Then the 2-DE gel imaging showed that 74, 36 and 31 differential protein spots were found between OVC and OSCC, OVC and adjacent normal oral mucosa of OVC (OVCN), OSCC and adjacent normal oral mucosa of OSCC (OSCCN) samples, respectively. By identification of protein spots from 2-DE gels, 20 PMF maps were obtained by MALDI-TOF-MS including recoverin (cancer associated retinopathy (CAR) protein) tumor protein D53 (hD53), zinc finger protein 77 (ZNFpT1) and so on and these protein may play a key role in the carcinogenesis of OVC and OSCC. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Key words:&nbsp;Oral verrucous carcinoma, oral squamous cell carcinoma, two-dimensional electrophoresis, peptide mass fingerprints, matrix-assisted laser desorption/ionization-time of flight mass spectrometry.