Retinoic acid receptor-alpha as a prognostic indicator in oral squamous cell carcinoma

Integrated analysis of miRNA-mRNA networks reveals a strong anti-skin cancer signature in vitiligo epidermis

Expression of microRNAs (miRNAs) is often dysregulated in several cancers, including non-melanoma skin cancer (NMSC). Individuals with vitiligo possess a deregulated miRnome along with a lower risk of developing NMSCs. We used data sets from our previously published studies on vitiligo epidermis to construct functional miRNA-mRNA networks to understand the molecular basis underlying the lower incidence of NMSC observed in individuals with vitiligo. miRTarBase database was used to fetch the experimentally validated targets of differentially expressed miRNAs and two protein-protein interaction (PPI) networks were constructed for the miRNA-mRNA interactions (230 downregulated targets of 5 upregulated miRNAs and 47 upregulated mRNAs targeted by 12 downregulated miRNAs). Pathway enrichment analysis identified RNA biogenesis and transport as well as cell adhesion to be perturbed in vitiligo. Further, oncogenic transcription factors (OTFs) that were upregulated in publicly available squamous cell carcinoma (SCC) or basal cell carcinoma (BCC) microarray data were compared with that of vitiligo to decode skin cancer-specific molecular signatures. We identified three significantly upregulated miRNAs, miR-31-5p, miR-31-3p and miR-194-3p in lesional epidermis that could negatively regulate seven oncogenic transcription factors, FOXC1, AR, SP1, YY1, GLI2, TP53 and RARA, known to be over-expressed in SCC or BCC. Taken together, our study identified a perturbed miRNA-regulated transcriptome, which potentially confers protection to vitiligo skin from an increased incidence of NMSC.

CYP26A1 Is a Novel Biomarker for Betel Quid-Related Oral and Pharyngeal Cancers

Betel quid (BQ) has been classified as a Group I human carcinogen in light of evidence demonstrating an association with an elevated risk of oral and pharyngeal cancers. To date, the incidence rate of oral and pharynx cancers among Taiwanese men ranks the highest worldwide. However, no study has yet confirmed variants of CYP26A1 was associated with the risks of oral and pharyngeal cancers. A case-control study was conducted (n = 339). CYP26A1 polymorphism was performed using SNP assay. Real-time qRT-PCR and Western blotting were used to determine the levels of CYP26A1 expression. The cancer cell model involved treatment with arecoline. Our findings showed that the downregulation of CYP26A1 mRNA and protein expression are more frequently observed in cancerous tissues than adjacent normal tissues in patients with oral and pharynx cancers (p < 0.01). We found that CYP26A1 was downregulated as the arecoline dose increased. We hypothesized that lower levels of CYP26A1 mRNA expression can be utilized a clinically biomarker causes oral and pharynx cancers. Arecoline appears to modulate CYP26A1 expression through specific pathways. Carriers of CYP26A1 SNP, rs2068888 (G/G)/rs4418728 (G/G) and who have lower levels of CYP26A1 expression are associated with an increased risk of oral and pharyngeal cancers.

Risk Categorization with Different Grades of Cervical Pre-Neoplastic Lesions - High Risk HPV Associations and Expression of p53 and RARβ

Objective:

To identify high risk HPV associations by evaluating linked p16 overexpression and also the expression of p53 and RARβ together with histopathology for risk categorization of cervical pre-neoplastic lesions.

Materials and Methods:

Immunohistochemical staining was performed on 100 cases of cervical pre- neoplastic lesions for expression of biomarkers like p16, p53 and RARβ for comparison with haematoxylin/eosin (HE) findings. All the experimentally generated data were statistically analyzed.

Results:

In this study 70% cases showed overexpression of p16INK4A increasing progressively from CIN I to CIN II but reduced in CIN III (p <0.01). p53 oncoprotein expression was seen in 51% cases, again with increments from CIN I to CIN II with slight reduction in CIN III (p<0.01). Some 24% cases showed negative immunoreactivity for the putative tumor suppressor gene RARβ (p>0.05).

Conclusion:

Our study provides support for the idea that p16 can be used to identify associations with HPV , as well as having potential along with p53 and RARβ for categorizing cervical pre-neoplastic cases having a higher risk of neoplastic conversion. Thus it may be concluded that accurate risk categorization can be achieved with the help of genetic markers as well as histopathology.

Efficiency of All-Trans Retinoic Acid on Gastric Cancer: A Narrative Literature Review

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide with a five-year survival rate of around 25%, and 4% when diagnosed at a metastatic stage. Cancer stem cells (CSC) have recently been characterized as being responsible for resistance to radio/chemotherapies and metastasis formation, opening up perspectives for new targeted therapies. Those CSCs express biomarkers such as cluster of differentiation 44 (CD44) and display high aldehyde dehydrogenase activity that converts vitamin A-derived retinal into retinoic acids. All-trans retinoic acid (ATRA), which has pro-differentiating properties, has revolutionized the prognosis of acute promyelotic leukemia by increasing its remission rate from 15% to 85%. Recent studies have started to show that ATRA also has an anti-tumoral role on solid cancers such as GC. The purpose of this review is therefore to summarize the work that evaluated the effects of ATRA in GC and to evaluate whether its anti-cancerous action involves gastric CSCs targeting. It has been demonstrated that ATRA can block the cell cycle, enhance apoptosis, and decrease gastric CSCs properties in GC cell lines, tumorspheres, and patient-derived xenograft mice models. Therefore, retinoids and new synthetic retinoids seem to be a promising step forward in targeted therapy of gastric CSC in combination with existing chemotherapies. Future studies should probably focus on these points.

Clinical significance and prognostic value of TRIM24 expression in esophageal squamous cell carcinoma

Tripartite motif-containing 24 (TRIM24), a member of the transcription intermediary factor 1 family, is defined as a co-regulator with several nuclear receptors, such as RARα. TRIM24 has been reported to be involved in many cancers. In this study, we aimed to investigate the expression pattern and prognostic significance of TRIM24 and its relationship with RARα in esophageal squamous cell cancer (ESCC). Both mRNA and protein expression levels of TRIM24 were found to be significantly decreased in ESCC, as judged by qRT-PCR and western blot. Immunohistochemistry staining shows that the reduced TRIM24 protein is associated with lymph node metastasis (P=0.024), advance pathological TNM (pTNM) stage (P=0.046) and recurrence/metastasis (P=0.001). Upregulated TRIM24 protein predicts longer overall survival and disease-free survival (both P<0.001) and is an independent predictor for good prognosis (HR, 0.519; 95%CI, 0.341-0.788; P=0.002). TRIM24 expression has been proven remarkably to improve prediction of survival of pTNM stage in ESCC patients, especially in stage I and II. However, no significant relationship was found between TRIM24 and RARα expression levels. In conclusion, reduced TRIM24 protein is associated with poor survival in ESCC patients, suggesting TRIM24 protein is a potential prognostic biomarker for ESCC.

Retinoic Acid Receptor β: A Potential Therapeutic Target in Retinoic Acid Treatment of Endometrial Cancer

OBJECTIVE

Several studies have reported that retinoic acid (RA) might be used to treat malignancies. The effects of RA are mediated by the RA receptor (RAR), and RARα/RARβ especially acts as a tumor suppressor. However, little is known about its role in human endometrial cancer.

MATERIALS AND METHODS

In this study, we examined the effects of all-trans RA (ATRA) on progression of human endometrial cancer cell line, RL95-2 and Hec1A. We then examined the expression of RARα and RARβ in 50 endometrial cancer tissues by using immunohistochemistry.

RESULTS

We found inhibitory effects of ATRA on cell proliferation, apoptosis, and migration in RL95-2 cells, but not in Hec1A cells. RARα or RARβ knockdown individually could not cancel out the inhibition of cell proliferation by ATRA in RL95-2 cells, but simultaneous knockdown of RARα and RARβ could block its effect on proliferation. RARα and RARβ knockdown dose dependently reduced the inhibition of migration by ATRA, but the effect was more pronounced with RARβ knockdown than with RARα knockdown. We confirmed that RARβ gene was directly regulated by ATRA in microarray and real-time reverse transcription polymerase chain reaction. Furthermore, the RARβ agonist (BMS453) significantly suppressed proliferation of RL95-2 cells. In immunohistochemical analysis, RARα expression was positively correlated with tumor grade, and RARβ showed the opposite tendency in endometrial cancer.

CONCLUSIONS

Retinoic acid might have multiple antitumor effects, and RARβ may be a potent therapeutic target in RA treatment for endometrial cancers.

Retinoid receptors in gastric cancer: expression and influence on prognosis

BACKGROUND

Gastric cancer is frequently lethal despite aggressive multimodal therapies, and new treatment approaches are therefore needed. Retinoids are potential candidate drugs: they prevent cell differentiation, proliferation and malignant transformation in gastric cancer cell lines. They interact with nuclear retinoid receptors (the retinoic acid receptors [RARs] and retinoid X receptors [RXRs]), which function as transcription factors, each with three subclasses, α, β and γ. At present, little is known about retinoid expression and influence on prognosis in gastric cancers.

PATIENTS AND METHODS

We retrospectively analyzed the expression of the subtypes RARα, RARβ, RARγ, RXRα, RXRβ, RXRγ by immunohistochemistry in 147 gastric cancers and 51 normal gastric epithelium tissues for whom clinical follow-up data were available and correlated the results with clinical characteristics. In addition, we quantified the expression of retinoid receptor mRNA using real- time PCR (RT-PCR) in another 6 gastric adenocarcinoma and 3 normal gastric tissues. From 2008 to 2010, 80 patients with gastric cancers were enrolled onto therapy with all-trans-retinoic acid (ATRA).

RESULTS

RARα, RARβ, RARγ and RXRγ positively correlated with each other (p<0.001) and demonstrated significantly lower levels in the carcinoma tissue sections (p<0.01), with lower RARβ, RARγ and RXRα expression significantly related to advanced stages (p<=0.01). Tumors with poor histopathologic grade had lower levels of RARα and RARβ in different histological types of gastric carcinoma (p<0.01). Patients whose tumors exhibited low levels of RARa expression had significantly lower overall survival compared with patients who had higher expression levels of this receptor (p<0.001, HR=0.42, 95.0% CI 0.24-0.73), and patients undergoing ATRA treatment had significantly longer median survival times (p=0.007, HR=0.41, 95.0% CI 0.21-0.80).

CONCLUSIONS

Retinoic acid receptors are frequently expressed in epithelial gastric cancer with a decreased tendency of expression and RARa may be an indicator of a positive prognosis. This study provides a molecular basis for the therapeutic use of retinoids against gastric cancer.

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

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

Transcription factors: their potential as targets for an individualized therapeutic approach to cancer

Pro-cancer signals are controlled by the expression and transcription of oncogenes. Transcription of DNA is dependent on the spatially and temporally coordinated interaction between transcriptional machinery (RNA polymerase II, transcription factors (TFs)) and transcriptional regulatory components (promoter elements, enhancers, silencers and locus control regions). Unique TFs have been identified in association with cancer. This review summarizes key oncogene-related TFs and organizes their pro-cancer activity according to the six hallmark functions (self sufficiency in growth signals, insensitivity to growth-inhibitory signals, evasion of programmed cell death, limitless replicative potential, sustained angiogenesis and metastatic spread) proposed as constituting the infrastructure of the malignant process.

Clinical significance of mannose-binding lectin-associated serine protease-2 expression in esophageal squamous cell carcinoma

Mannan-binding lectin-associated serine protease-2 (MASP-2) is a serine protease involved in the activation of lectin complement pathway. The differential expression of MASP-2 in human esophageal squamous cell carcinoma (ESCC) was recently reported from our laboratory using differential display. To determine the expression of MASP-2 protein, we raised a polyclonal antibody to human MASP-2 and used it for immunohistochemical analysis of MASP-2 in ESCCs. The antibody showed a single band of predicted molecular weight by western blotting. In normal human liver tissue, the cytoplasm was distinctly labeled by the antibody. Intriguingly, besides the cytoplasm, the nuclei of esophageal tumor cells were also labeled. To investigate the association of MASP-2 expression with esophageal tumorigenesis, its expression was analyzed in 51 primary ESCCs, 32 dysplasias, 21 histologically normal esophageal tissues and 6 adenocarcinomas by immunohistochemistry. Increased MASP-2 expression was observed in ESCCs (p = 0.001, Odd's ratio (OR) = 3.662) and in premalignant condition, dysplasia (p = 0.000, OR = 5.091) in comparison with the normal tissues. MASP-2 expression in ESCCs was associated with late clinical stage (p = 0.009, O.R. = 3.430) and nodal metastasis (p = 0.001, O.R. = 4.520). In conclusion, our antibody was demonstrated to be useful in recognizing MASP-2 expression on paraffin embedded tissue sections. To our knowledge, this is the first report showing MASP-2 expression in a solid tumor. MASP-2 expression in premalignant stage (dysplasia) as well as in ESCCs and its association with late clinical stage and nodal metastasis suggest that alteration in its expression is maintained during disease progression and is associated with aggressive tumor behavior.

Expression of retinoid receptors in sebaceous cell carcinoma

PURPOSE

The aim of this study is to investigate whether there are any abnormalities in the in vivo expression of retinoid acid receptors (RAR-alpha, RAR-beta and RAR-gamma) and retinoid X receptors (RXR-alpha, RXR-beta and RXR-gamma) in sebaceous cell carcinoma.

METHODS

Expression of retinoid receptors in paired specimens of cancerous tissues (n = 10) and adjacent normal tissues (n = 10) from 10 patients with sebaceous cell carcinoma was studied immunohistochemically by using anti-retinoid receptor antibodies.

RESULTS

In eight of the 10 normal tissue samples, all six receptors were expressed. In the other two samples, all receptors were expressed except RAR-gamma (one sample) or RXR-gamma (two samples). Five tumours (50%) lacked RAR-alpha; RAR-alpha expression was lower in tumours than in normal tissues in eight of 10 cases. RAR-beta was expressed in the cytoplasm of nine of 10 tumours; RAR-beta expression was at least as high in tumours as in normal tissue in eight of 10 cases. Two tumours lacked RAR-gamma; three tumours had lower RAR-gamma expression than paired normal epithelium; four had the same RAR-gamma expression, and one had higher RAR-gamma expression. RXR-alpha expression was strong in all normal tissues and tumour samples. Ten tumours lacked RXR-beta and all 10 tumours lacked RXR-gamma expression.

CONCLUSIONS

Diminished RXR-beta and RXR-gamma expression might be related to the development of sebaceous cell carcinoma. Additional studies are required to establish whether the defects in RAR expression in sebaceous cell carcinoma might affect the potential response of this tumour to treatment with retinoids.

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

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

MEMD/ALCAM: A Potential Marker for Tumor Invasion and Nodal Metastasis in Esophageal Squamous Cell Carcinoma

OBJECTIVE

The MEMD gene was reported to be overexpressed in human esophageal squamous cell carcinoma (ESCC), using differential display. The aim of this study was to determine the clinical significance of MEMD/ALCAM in esophageal tumorigenesis.

METHODS

Analysis of MEMD/ALCAM expression in esophageal tissues was carried out at protein and RNA level using immunohistochemistry and semiquantitative RT-PCR, respectively.

RESULTS

Increased MEMD/ALCAM expression was observed in 42/65 (65%) ESCCs (p = 0.000, odds ratio, OR = 3.665) and in 17/25 (68%) dysplasias (p = 0.000, OR = 4.248) compared to paired distant histologically normal esophageal tissues. Increased MEMD mRNAlevels were observed in ESCCs and dysplasias showing overexpression of MEMD/ALCAM protein. Interestingly, increased membranous MEMD/ALCAM expression was observed in dysplasias in comparison with ESCCs (p = 0.002, OR = 3.177). MEMD/ALCAM overexpression in ESCCs was associated with late clinical stage (p = 0.002, OR = 3.619), enhanced tumor invasiveness (p = 0.002, OR = 3.619), and nodal metastasis (p = 0.000, OR = 4.206).

CONCLUSION

To our knowledge, this is the first report showing MEMD expression at pre-malignant stage (dysplasia), suggesting that MEMD/ALCAM expression is an early event in the development of esophageal cancer. Furthermore, in ESCCs its correlation with late clinical stage, enhanced tumor invasiveness and nodal metastasis suggests an association with aggressive tumor behavior. Our data suggest that MEMD/ALCAM may serve as a potential marker for early diagnosis, tumor invasion and nodal metastasis in ESCCs.

Retinoid receptors in ovarian cancer: expression and prognosis

BACKGROUND

Ovarian cancer is frequently lethal despite aggressive multimodal therapy, and new therapies are therefore needed. Retinoids are potential candidate drugs: they prevent the development of ovarian carcinoma and enhance the efficacy of cytotoxic drugs in ovarian cancer cells. At present, little is known about the retinoid receptor expression in ovarian cancer.

PATIENTS AND METHODS

The retinoid receptors comprise two classes, retinoic acid receptors (RARs) and retinoid X receptors (RXRs), each with three subclasses, alpha, beta and gamma. We investigated the expression of the subtypes RARalpha, RARgamma, RXRalpha and RXRbeta by immunohistochemistry in ovarian cancers of 80 patients, and assessed their prognostic significance. In addition, we quantified the expression of retinoid receptor mRNA using real-time PCR and correlated the results with clinical characteristics.

RESULTS

RARalpha and RXRbeta were highly expressed in a majority of ovarian cancers, particularly in advanced stages. High expression of RARalpha was an independent negative prognostic factor of survival in addition to FIGO stage, age and p53 accumulation. The mRNA expression of retinoid receptors did not correlate with clinical properties of the tumors.

CONCLUSIONS

Retinoic acid receptors are frequently and strongly expressed in epithelial ovarian cancer and may be indicators of an adverse prognosis. This study provides the molecular basis for the therapeutic use of retinoids in ovarian cancer.

Identification of differentially expressed genes in oral squamous cell carcinoma

Rapid advances in multimodality therapy have not significantly improved the overall 5-yr survival of oral cancer patients in the past two decades, thereby underscoring the need for molecular therapeutics. The development of new treatment strategies for more effective management of oral cancer requires identification of novel biological targets. Therefore, the aim of this study was to identify novel genes associated with oral tumorigenesis by comparing gene expression profile of oral squamous cell carcinomas (OSCCs) and matched nonmalignant oral epithelial tissues with differential display. Of the 180 differentially expressed cDNAs isolated, reamplified, and cloned into pGEMT-Easy Vector, 26 cDNAs were confirmed to be upregulated in OSCCs by reverse Northern blot analysis. The differentially expressed genes included components of immune system, signaling pathways, angiogenesis, cell structure, proliferation, apoptosis, cell-adhesion, and cellular metabolism. Reverse transcription (RT)-polymerase chain reaction (PCR) analysis of 15 OSCCs and matched nonmalignant oral tissues provided the first evidence that 14-3-3-zeta, melanoma metastasizing clone D (MEMD), KIAA0471, sperm protein 17 (SP17), TC21, and anti-TNF alpha antibody are upregulated in OSCCs. Immunohistochemical analysis confirmed overexpression of 14-3-3-zeta and TC21 protein, a member of the Ras family, in OSCCs as compared to histologically normal oral tissues validating the differential display analysis. Identification of six novel differentially expressed genes in oral tumors adds to the repertoire of genes associated with oral carcinogenesis and provides candidate potential biological targets for diagnosis and/or therapy. Further characterization of the 14 unknown differentially expressed cDNAs identified in this study may provide significant clues for understanding the molecular mechanisms underlying oral tumorigenesis.

Differential expression of the non-receptor tyrosine kinase BRK in oral squamous cell carcinoma and normal oral epithelium

BRK is a non-receptor tyrosine kinase whose functional role is poorly understood. Although it is an epithelial specific kinase, its expression appears to be tissue specific. To date, little is known about BRK expression in human oral epithelium. We investigated expression of BRK in human oral squamous cell carcinomas (OSCC) and normal oral epithelium (NOE) using immunohistochemistry, laser confocal microscopy and Western blotting. The subcellular localization of BRK was identified by confocal microscopy and Western blotting of nuclear and cytoplasmic extracts from these cells. The results indicate that NOE express higher levels of BRK compared with OSCC cells. In NOE and moderately differentiated OSCC cells, BRK was localized in the nucleus and cytoplasm. However, in poorly differentiated OSCC cells, BRK was localized in perinuclear regions. These results suggest that BRK expression differs in normal and OSCC which may reflect a possible functional involvement in OSCC.

Expression of the Epidermal Growth Factor Seven-Transmembrane Member CD97 Correlates with Grading and Staging in Human Oral Squamous Cell Carcinomas

Introduction: The oral squamous cell carcinoma (OSCC) is the sixth most common malignant tumor worldwide. No significant better progress has been made in the treatment of OSCCs during the last decades. The heterodimeric CD97 protein is a epidermal growth factor seven-transmembrane family member and was identified as a dedifferentiation marker in thyroid carcinomas. Nothing is known about CD97 in OSCCs.

Material and Methods: Employing UV-laser microdissection, CD97 and its ligand CD55 were investigated in normal oral mucosa and OSCCs (n = 78) by multiplex reverse transcription-PCR. Frozen sections were investigated by immunohistochemistry. The effects of retinoic acid and sodium butyrate on the CD97/CD55 expression in OSCC cell lines were determined by quantitative PCR, immunocytochemistry, and flow cytometry.

Results: Weak CD97 transcripts were expressed in normal mucosa and normal basal epithelial cells revealed specific CD97 immunostaining. Strong CD97 transcripts were detected in pT3/T4 and G3/G4 OSCC tissues, whereas pT1/T2 and G1/G2 carcinomas revealed weak CD97 transcript levels. A weak CD97 immunostaining was observed in pT1/T2 and G1/G2 tumors. By contrast, intensive CD97 immunostaining was detected in pT3/T4 OSCCs and G3/G4 lesions. CD55 gene expression was low in normal mucosa. All OSCCs, irrespective of stage and grading, displayed strong CD55 immunostaining. Sodium butyrate and retinoic acid inhibited CD97 mRNA and protein in OSCC cell lines. Interestingly, CD55 was up-regulated by both substances.

Conclusion: We identified CD97 as a novel marker of dedifferentiated OSCC. Interaction of CD97 and CD55 may facilitate adhesion of OSCC cells to surrounding surfaces that would result in metastases and bad prognosis.

Establishment and characterization of a cell line from smokeless tobacco associated oral squamous cell carcinoma

A cell line, AMOS-III has been established from the surgically resected specimen of an untreated primary human oral squamous cell carcinoma of the floor of mouth from a chronic smokeless tobacco consumer. Immunocytochemical analysis showed epithelial specific antigen, cytokeratins 5, 10, 13 and 16 and integrin alpha(6) markers in AMOS-III cells, confirming the epithelial lineage of the cell line. Analyses of morphology, ultrastructure, karyotype, anchorage independent growth and immunocytochemical properties of the cell line demonstrated the transformed phenotype of epithelial cells. AMOS-III cells have doubling time of 42-44 h. Giemsa-banding patterns of chromosomes confirmed the human origin of the AMOS-III cells. Molecular analysis of cancer-related gene products, p53 and p21(cip1/waf1) showed the presence of wild type p21(cip1/waf1) and truncated p53 proteins. The molecular mechanism underlying the action of retinoids in preventing the occurrence of second primary tumors in oral cancer patients remain to be clearly defined. Treatment of AMOS-III cells with all-trans retinoic acid (ATRA) at 10(-4) microM resulted in 81% cell death. ATRA treatment resulted in enhanced expression of p21(cip1/waf1), nuclear translocation of retinoic acid receptors and apoptotic cell death. Thus, this cell line provides an in vitro model for elucidating the mechanism involving p53 inactivation and p21(cip1/waf1) overexpression in smokeless tobacco-induced oral cancer. Furthermore, the ATRA responsiveness of the cell line underscores its potential utility in identifying the retinoid responsive molecular targets in oral cancer cells.