Up-regulation of Fas ligand and down-regulation of Fas expression in oral carcinogenesis

Role of Cell Death in Cellular Processes During Odontogenesis

The development of a tooth germ in a precise size, shape, and position in the jaw, involves meticulous regulation of cell proliferation and cell death. Apoptosis, as the most common type of programmed cell death during embryonic development, plays a number of key roles during odontogenesis, ranging from the budding of the oral epithelium during tooth initiation, to later tooth germ morphogenesis and removal of enamel knot signaling center. Here, we summarize recent knowledge about the distribution and function of apoptotic cells during odontogenesis in several vertebrate lineages, with a special focus on amniotes (mammals and reptiles). We discuss the regulatory roles that apoptosis plays on various cellular processes during odontogenesis. We also review apoptosis-associated molecular signaling during tooth development, including its relationship with the autophagic pathway. Lastly, we cover apoptotic pathway disruption, and alterations in apoptotic cell distribution in transgenic mouse models. These studies foster a deeper understanding how apoptotic cells affect cellular processes during normal odontogenesis, and how they contribute to dental disorders, which could lead to new avenues of treatment in the future.

Effects of Notch signaling components from breast cancer cells treated in culture with resveratrol

Resveratrol (Res) has an anti-tumor effect. Notch signaling components from breast cancer cells treated in culture with Resveratrol was investigated. MDA-MB-231cells were divided into control group (Res-untreated) and Res-treated groups including six concentrations 0 μM, 10 μM, 20 μM, 40 μM, 80 μM and 160 μM. Cytotoxicity test were evaluated by CCK-8. The mRNA and Protein expression levels of Notch1, Jagged1, Dll4 and Hes-5 were detected by RT-PCR and Western blot. The mRNA expression of Notch1, Jagged1, Hes-5 and Dll4 in the Res administration group decreased significantly (0.01 < p < .05), and Hes-5 and Dll4 were extremely significant (p < .01). Compared with the blank control group, the protein expression of Notch1 and Dll4 decreased significantly in each concentration Res group, but the decrease of protein expression of Jagged1 and Hes-5 was not significant. In conclusion, Res regulates mRNA and protein expression of Notch1, Dll4 of MDA-MB-231 cells via Notch pathway.

Analysis of methylation and mRNA expression status of FADD and FAS genes in patients with oral squamous cell carcinoma

BACKGROUND

Apoptosis is an important mechanism that is responsible for the physiological deletion of harmful, damaged, or unwanted cells. Changed expression of apoptosis-related genes may lead to abnormal cell proliferation and finally to tumor genesis. Our aims were to analyze the promoter methylation and gene expression profiles of FADD and FAS genes in risk of OSCC.

MATERIAL AND METHODS

we analyze the promoter methylation status of FADD and FAS genes using Methylation - Specific PCR (MSP) in 86 OSCC tissues were kept in paraffin and 68 normal oral tissues applied as control. Also, FADD and FAS genes expression were analyzed in 19 cases and 20 normal specimens by Real-Time Reverse-Transcripts PCR.

RESULTS

Aberrant promoter methylation of FADD and FAS genes were detected in 12.79 % (11 of 86) and 60.46 % (52 of 86) of the OSCC cases, respectively, with a significant difference between cases and healthy controls for both FADD and FAS genes (P < 0.001). The gene expression analysis showed statistically significant difference between cases and healthy controls for both FADD (p<0.02) and FAS (p<0.007) genes.

CONCLUSIONS

To the best our knowledge, the data of this study are the first report regarding, the effect of promoter hypermethylation of the FADD and FAS genes in development of OSCC. To confirm the data, it is recommended doing further study in large sample sizes in various genetic populations.

Efficient growth suppression and apoptosis in human laryngeal carcinoma cell line HEP-2 induced by an adeno-associated virus expressing human FAS ligand

BACKGROUND

Apoptosis induced by Fas/FasL system has been proposed as a gene therapy methold for various cancers.

METHODS

We used adeno-associated virus-expressing enhanced green fluorescent protein (EGFP)-human FasL (AAV-EGFP-hFasL) to deliver FasL into Hep-2 cells, cytotoxicity was detected by MTS assay , apoptosis was confirmed by flow cytometry. We also treated the xenograft of Hep-2 tumor in nude mice with intratumoral injection of AAV-EGFP-hFasL. The size of the xenograft, the apoptosis in the xenograft, and the survival rate of the inoculated mice were then evaluated.

RESULTS

Hep-2 cells infected with AAV-EGFP-hFasL showed increased apoptosis rate and killing effect compared with AAV-EGFP-infected cells. In addition intratumoral injections of AAV-EGFP-hFasL into Hep-2 xenografts induced significant growth suppression of tumors.

CONCLUSION

Our findings suggest that the introduction of FasL into head and neck squamous cell carcinoma may induce significant apoptosis, and adeno-associated virus may be a useful vehicle for gene therapy.

Topical pimecrolimus effect on Fas inducing apoptosis in oral lichen planus: a clinical immunohistochemical study

OBJECTIVE

To investigate the effectiveness of pimecrolimus treatment in patients not responding to corticosteroid treatment and to investigate its effect on Fas expression on keratinocytes in oral lichen planus (OLP).

SUBJECTS AND METHODS

Twenty patients with OLP were recruited from the Oral Medicine Clinic at the School of Dentistry, Ain Shams University, Egypt. Pimecrolimus 1% cream with a hydrophilic adhesive gel base was applied to the oral lesions, four times daily, for a total of 2 months. A marker lesion was identified and assessed by clinical scoring (CS). The symptomatology score was obtained using a visual analog scale (VAS). Pre-treatment and post-treatment specimens were immunohistochemically stained for detecting Fas.

RESULTS

The results of clinical scores showed statistically high significant improvement (P = 0.0001). The mean VAS decreased significantly over time as well as the mean of Fas expression (P < 0.05). The overall percentage of reduction from baseline to week 8 was 87%, 93%, and 67% for clinical scores, visual analog score, and Fas expression, respectively.

CONCLUSIONS

Topical pimecrolimus reduced Fas expression, and it appears to be a promising alternative treatment for OLP.

Polymorphisms in the apoptosis-associated genes FAS and FASL and risk of oral cancer and malignant potential of oral premalignant lesions in a Taiwanese population

BACKGROUND

Our aim was to measure the relationship of FAS (-1377G>A and -670A>G), FASL (-844C>T) gene variants and risk of oral cancer.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used to determine the FAS and FASL polymorphisms in 294 oral squamous cell carcinoma (OSCC), 53 oral submucous fibrosis (OSF), and 84 oral leukoplakia (OL) patients, as well as in 333 healthy controls. A standardized questionnaire was applied to collect demographic data, and potential confounding factors. JMP statistical software was used to analyze the association.

RESULTS

FAS and FASL polymorphisms were not correlated with OSCC development or the malignant potential of OL by simple and multivariate logistic regression. However, a two- to fourfold difference in the risks of betel quid chewing, alcohol consumption, and smoking on OSCC development were observed between participants with different FAS polymorphisms. FAS polymorphisms were significantly correlated with the malignant potential of OSF. Multivariate logistic regression analysis indicated that FAS A(-1377)-G(-670) vs. G(-1377)-A(-670) haplotype (OR = 2.26, 95% CI = 1.16-4.41) was correlated with the malignant potential of OSF.

CONCLUSIONS

We suggest that FAS and FASL polymorphisms are not significantly correlated with OSCC development or malignant potential of OL. The impact of substance usage on OSCC development could be differentiated by FAS polymorphisms. FAS A(-1377)-G(-670) haplotype may play a role in the malignant potential of OSF.

Cancer stem cells as targets for cancer therapy: selected cancers as examples

It is becoming increasingly evident that cancer constitutes a group of diseases involving altered stem-cell maturation/differentiation and the disturbance of regenerative processes. The observed malignant transformation is merely a symptom of normal differentiation processes gone astray rather than the primary event. This review focuses on the role of cancer stem cells (CSCs) in three common but also relatively under-investigated cancers: head and neck, ovarian, and testicular cancer. For didactic purpose, the physiology of stem cells is first introduced using hematopoietic and mesenchymal stem cells as examples. This is followed by a discussion of the (possible) role of CSCs in head and neck, ovarian, and testicular cancer. Aside from basic information about the pathophysiology of these cancers, current research results focused on the discovery of molecular markers specific to these cancers are also discussed. The last part of the review is largely dedicated to signaling pathways active within various normal and CSC types (e.g. Nanog, Nestin, Notch1, Notch2, Oct3 and 4, Wnt). Different elements of these pathways are also discussed in the context of therapeutic opportunities for the development of targeted therapies aimed at CSCs. Finally, alternative targeted anticancer therapies arising from recently identified molecules with cancer-(semi-)selective capabilities (e.g. apoptin, Brevinin-2R) are considered.

Histone deacetylase inhibitor suberoylanilide hydroxamic acid induces apoptosis through both mitochondrial and Fas (Cd95) signaling in head and neck squamous carcinoma cells

Alterations in histone acetylation status have been implicated in carcinogenesis. Histone deacetylase inhibitors, such as suberoylanilide hydroxamic acid (SAHA), can potentially reactivate aberrantly silenced genes by restoring histone acetylation and allowing gene transcription. However, the mechanisms underlying the effects of SAHA on cell growth, differentiation, and death remain unclear. In this study, we assessed the activity of SAHA in modulating cell growth and apoptosis in head and neck squamous cell carcinoma (HNSCC) cells compared with premalignant leukoplakia and normal oral cells. SAHA induced growth inhibition, cell cycle changes, and apoptosis in HNSCC cell lines but had limited effects on premalignant and normal cells. Although SAHA triggered the mitochondrial pathway of apoptosis, including cytochrome c release, caspase-3 and caspase-9 activation, and poly(ADP-ribose) polymerase cleavage in HNSCC cells, specific inhibition of caspase-9 only partially blocked the induction of apoptosis induction. SAHA also activated the extrinsic apoptosis pathway, including increased Fas and Fas ligand (FasL) expression, activation of caspase-8, and cleavage of Bid. Interfering with Fas signaling blocked apoptosis induction and blunted growth inhibition by SAHA. Our results show for the first time that SAHA induces apoptosis in HNSCC cells through activation of the Fas/FasL death pathway in addition to the intrinsic mitochondrial pathway although having comparatively little activity against precancerous and normal oral cells with intrinsic Fas and FasL expression.

Establishment and characterization of a tumorigenic cell line from areca quid and tobacco smoke-associated buccal carcinoma

A cell line, TW2.6, has been established from the surgically resected specimen of an untreated primary squamous cell carcinoma of the buccal mucosa from a 48-year-old man who was an areca quid chewer and tobacco smoker. TW2.6 cells exhibited morphological features of keratinocytes and replicated rapidly in culture with a doubling time of 24h. The karyotype showed human chromosomes with high hyperdiploidy and complex rearrangements. Western blotting showed pronounced expression of p53 and moderate expression of p21(CIP1). The baseline expressions of p27(KIP1) and p16(INK4a) were barely detectable. Low levels of Bax and Fas were found in TW2.6 cells but Bcl-2 expression was more readily observed. Mutational analysis of p53 gene revealed an A-->G transition at the second base of codon 220, resulting in amino acid substitution from tyrosine to cysteine in the protein. Functional analysis showed that TW2.6 was unable to activate the p53-specific PUMA promoter. Lipofectamine 2000 and calcium phosphate precipitation technique offer good transfection efficiencies for TW2.6 cells and may be used in future transfection experiments. A xenograft-SCID mouse tumor model was established for TW2.6. Histological examination demonstrated that the engrafted tumors maintained the morphological features of a squamous cell carcinoma. It is thought that the establishment of tumorigenic TW2.6 cell line provides a valuable model for AQ and tobacco smoke-associated buccal carcinoma.

Molecular markers of head and neck squamous cell carcinoma: promising signs in need of prospective evaluation

BACKGROUND

The aim of this article is to review recent developments in the biological understanding of head and neck squamous cell carcinomas.

METHODS AND RESULTS

We describe the markers according to their function and their prognostic or predictive roles. Some associations can be found between molecular markers and invasiveness, aggressiveness, degree of differentiation, and tumor stage, but only a few clinical studies have shown an impact on prognosis. In addition, despite an increasing number of articles relating to this topic, the small number of patients included in the studies reported reduces the clinical implications of these results. Few studies applied a more comprehensive molecular analysis approach, such as DNA microarrays or differential expression profiling by polymerase chain reaction, to identify a combination of markers that could be more informative than a single molecular marker.

CONCLUSION

Some progress has been made with respect to molecular markers and head and neck cancers. Translational and prospective, hypothesis-driven research must proceed with sufficient rigor to facilitate the clinical applicability of such results.

beta-Catenin, Nf-kappaB and FAS protein expression are independent events in head and neck cancer: study of their association with clinical parameters

In spite of much effort, no good markers have yet been found for predicting prognosis or response to therapy in advanced head and neck squamous cell carcinoma (HNSCCs) patients. beta-catenin, a protein involved in the cytoskeleton, cell-cell adhesion and gene transcription, is a factor associated with tumour progression. Recently, an interaction has been reported between beta-catenin, and NF-kappaB coupled with an inverse association of beta-catenin, and FAS (CD95/APO-1) protein expression in breast and colorectal tumours. To confirm these observations and to test their clinical impact in HNSCCs we have evaluated the expression of beta-catenin, NF-kappaB and FAS proteins. We used tissue microarrays to simultaneously analyse the levels of these proteins immunohistochemically in 118 HNSCCs. Among the 113 tumours evaluable for beta-catenin, increased and decreased levels were detected in 41 (36%) and 62 (55%) of the tumours, respectively. beta-catenin, protein staining was mainly membranous but 10 tumours (9%) showed the clear presence of protein in the cytoplasm, and none in the nucleus. Moreover, 81% of the tumours had decreased FAS protein expression, indicating that loss of FAS protein is a common feature of HNSCCs. Abnormal or nuclear NF-kappaB staining was observed in 24% of the tumours. No association was detected between the expression levels of the proteins evaluated. Regarding clinical associations, tumours from the hypopharynx had significantly lower levels of beta-catenin expression than those from other locations (P<0.05). Moreover, our data revealed that patients whose tumours had low levels of beta-catenin protein expression had decreased survival probability (24.8 months vs. NR, P=0.03) and reduced response to therapy (15.4 vs. 43 months; P=0.01) compared with patients whose tumours had high levels of beta-catenin. Taken together, our observations indicate that beta-catenin, NF-kappaB and FAS expression are independent events during HNSCC development and that levels of beta-catenin protein may identify subsets of advanced HNSCCs patients with different prognosis and response to therapy capabilities.

Expression of Fas and Fas-ligand and analysis of argyrophilic nucleolar organizer regions in squamous cell carcinoma: relationships with tumor stage and grade, and apoptosis

The aim of this study was to investigate whether levels of Fas and Fas-ligand (Fas-L) expression in oral and oropharyngeal squamous cell carcinomas (SCCs) are associated with tumor stage and grade, and to assess whether parameters related to argyrophilic nucleolar organizer regions (AgNORs) correlate with apoptosis in SCC cells and adjacent normal epithelium. Fifty-two specimens taken from the tumoral and neighboring normal tissues of 26 patients with oral and oropharyngeal SCC were analyzed for Fas/Fas-L expression, and 24 specimens from 12 patients for AgNOR parameters. Seventeen (65%) of the tumors were Fas and/or Fas-L-positive (by immunohistochemistry). A significant positive correlation was found between Fas/Fas-L expression and clinical tumor stage (P<0.01). Mean AgNOR number per nucleus, AgNOR size and the percentage area of each nucleus occupied by AgNORs (percent of nuclear area) were significantly increased in the SCC cells (4.49+/-1.28, 4.48+/-1.42, 5.56+/-1.22, respectively) when compared with the control neighboring squamous epithelial cells (2.58+/-0.61, 1.64+/-0.59 and 4.35+/-0.62%, respectively) (P<0.01). A significant positive correlation was found between the AgNOR parameters and Fas/Fas-L expression as apoptotic markers in the tumoral cells of SCC (P<0.05). There was also a significant positive correlation between the AgNOR parameters and the grading of tumors (P<0.05). In conclusion, AgNOR count was a strong proliferation marker in patients with SCC, and Fas and Fas-L staining was useful in tumor grading.

Apoptosis in normal and diseased oral tissues

Apoptotic cell death plays an important role in maintenance of the normal physiological state and in the pathogenesis of diseases in the body. Over the last three decades the molecular mechanisms of apoptosis have been unravelled leading to development of novel therapeutic approaches. This paper aims to present current knowledge of the role of apoptosis in normal oral tissues and in the development of oral diseases.

Increased Fas ligand expression by T cells and tumour cells in the progression of actinic keratosis to squamous cell carcinoma

BACKGROUND

In the counterattack model of tumorigenesis, it has been proposed that tumours develop resistance to attack from Fas ligand (FasL)-expressing cytotoxic T cells by downregulating Fas (immune escape), while at the same time upregulating FasL expression to induce apoptosis in Fas-expressing T cells (counterattack).

OBJECTIVES

The aim of this study was to examine Fas and FasL expression on tumour cells and infiltrating T cells during the progression of actinic keratoses (AK), the benign precursor lesion, to squamous cell carcinoma (SCC).

PATIENTS AND METHODS

Samples of AK (n = 20) and SCC (n = 20) were collected from immunocompetent patients attending dermatology clinics. Double-label immunohistochemistry was performed on frozen sections using mouse monoclonal antibodies to Fas or FasL, simultaneously with a rabbit polyclonal antibody to either CD3 or cytokeratin, markers of T cells and keratinocytes, respectively. Cell densities and the optical density of tumour Fas expression were measured using image analysis.

RESULTS

FasL-expressing T cells were observed in nine of 19 SCCs, compared with three of 20 AKs (P < 0.05). FasL-expressing tumour cells were found in nine of 18 SCCs, compared with only one of 20 AK specimens (P < 0.005). There was no difference in the number of Fas-expressing T cells infiltrating AK and SCC. Fas expression by keratinocytes, measured by optical density, was lower in SCC (range 0.1-40, median 17) compared with AK (range 4-62, median 25) (P < 0.05).

CONCLUSIONS

These results suggest that the greater numbers of FasL-expressing T cells infiltrating into SCC compared with AK are targeting Fas-expressing tumour cells. As AK cells progress to SCC, they subvert this T-cell-mediated killing of tumour cells by downregulating their Fas expression (immune escape). Furthermore, tumour cells upregulate their expression of FasL, possibly as a counterattack measure to induce apoptosis in the increased number of tumour-infiltrating T cells. Thus changes in Fas/FasL-mediated interactions between T cells and tumour cells occur during the progression of AK into SCC.

The role of apoptosis in oral disease: mechanisms; aberrations in neoplastic, autoimmune, infectious, hematologic, and developmental diseases; and therapeutic opportunities

Apoptosis is a genetically programmed form of cell death, which primarily functions to eliminate senescent or altered cells that are useless or harmful for the multicellular organism. Contrary to necrosis, apoptosis represents a physiologic cellular mechanism, normal function and control of which are critical for the development and homeostasis of multicellular organisms. In contrast, aberrations of the apoptotic mechanisms that cause excessive or deficient programmed cell death have been linked to a wide array of pathologic conditions. This review briefly summarizes the major apoptotic pathways and molecules and presents the most important oral diseases that are related to dysregulation of apoptosis. Knowledge of the association between aberrations in apoptotic mechanisms and human pathology hopefully will be implemented for the design of improved diagnostic and prognostic assays and the development of novel, more efficient, therapeutic strategies.

Prognostic relevance of molecular markers of oral cancer--a review

The aim of the present article was to review the current knowledge on the prognostic value of tumour marker in the treatment of oral squamous cell carcinoma (OSCC). The literature of the past 5 years (1997-August 2002) was screened. One hundred and sixty-nine articles were included in this review, twenty-nine molecular markers of relevance were identified. Tumour markers were allocated to four groups according to their function: (i) Enhancement of Tumour Growth: Cell cycle acceleration and proliferation, (ii) Tumour Suppression and Anti-Tumour Defence: Immune response and apoptosis, (iii) Angiogenesis, (iv) Tumour Invasion and Metastatic Potential: Adhesion molecules and matrix degradation. Data showed that the prognostic relevance of most tumour markers is still not quite clear. Only 12 of 23 reports on the prognostic relevance of markers for cell cycle acceleration and proliferation indicated a significant association with prognosis while 20 of 29 studies on markers for tumour suppression and anti-tumour response showed prognostic relevance. Markers of angiogenesis exhibited only minor importance for the prognosis and treatment of OSCC. Results on markers of tumour invasion and metastatic potential appeared to be too premature for a statement regarding their prognostic value. In general, the location of markers within the tumour and not their quantitative assessment as such is emphasized. Particularly, the analysis of the invasive front of the tumour with regard to the occurrence of molecular markers is supposed to be of great importance for prognostication.

[Genic alterations in oral and head and neck squamous cell carcinomas: analysis of international literature]

The development of oral and head and neck squamous cell carcinomas occurs in relation with multiple events including mainly: loss of cycle cell control, evasion from apoptosis, telomerase reactivation. Complex interactions between a set of molecules, cell cycle proteins, tumour suppressor genes, oncogenes and the telomerase, occur in the multiple step process of carcinogenesis. The 2 main ways of control of the cell cycle rely on 2 tumour suppressor genes: the P53 gene and the retinoblastoma gene or RB gene. One of the regulation pathways or the 2 regulation pathways are disabled during the development of oral and head and neck squamous cell carcinomas. Most of the time, the inactivation of the P53 pathway results from a loss of function of the p53 protein, secondary to mutation and/or deletion of the P53 gene; It may also result of the amplification of the MDM2 gene and of the inactivation of the arf protein. The RB pathway leads to cell proliferation by loss of the p16 protein, by amplification of the cyclin D1 gene and less frequently by mutation of the RB gene or loss of the retinoblastoma protein. In India and South-East Asia, the activation of RAS and MYC oncogenes appears to be related with the presence of specific carcinogens in snuff and tobacco. By blocking apoptosis, the Bcl2 protein seems to increase the resistance of tumours to radiotherapy and chemotherapy.

Cell death regulation in oral squamous cell carcinoma: methodological considerations and clinical significance

In the last three decades, more work has been done on apoptosis and its role in the pathogenesis of many diseases including cancer. In almost all instances of cancer, dysregulation of cell death (apoptosis) and cell proliferation have been found to play a major role in tumourigenesis. A lot of progress has been made on understanding the molecular basis of apoptosis and its regulatory mechanisms. This review focuses on current knowledge on the regulation of apoptosis in oral squamous cell carcinoma, current methodologies and methodological consideration in estimation of cell death in tissue sections and the clinical significance of apoptosis related molecules in progression of oral squamous cell carcinoma.

The unexplained survival of cells in oral cancer: what is the role of p53?

In normal oral epithelium the cells divide, mature, differentiate, and die. This sequence is not normally followed in oral cancer. Instead, the death of the cells is somehow prevented, although the pathways toward cell death in normal oral epithelium and the defects in oral cancer are not well defined. However, several components in the system have been identified, and information on their interactions is becoming available. This review summarizes the evidence for cell death being due to apoptosis and the central role of the p53 gene product in its regulation. Areas for future research are also identified.