Molecular biology of squamous cell carcinoma of the head and neck

Autophagy regulation in cancer development and therapy

Autophagy is a cellular process to degrade long-lived or malfunctioning proteins and obsolete or damaged organelles. It maintains cellular homeostasis and helps cells survive stressful conditions. Tumor suppressors mostly positively regulate autophagy, whereas oncogene products usually inhibit autophagy. Alterations in key autophagy genes have also been shown to affect cancer development. However, the role of autophagy in cancer depends on the status of the cells and can either suppress or promote tumor growth. In the present review, we report on the current state of knowledge about the reciprocal regulation of autophagy and the potential role of autophagy played in cancer development and therapy.

Reduced expression of mir15a in the blood of patients with oral squamous cell carcinoma is associated with tumor staging

MicroRNAs (miRNAs) mir15a and let7a are important regulators of bcl-2, ras and c-myc proteins. Considering that these miRNAs are commonly altered in many human cancers and that these proteins are reported to be altered in oral squamous cell carcinoma (OSCC), we investigated them in a set of OSCC cases. The miRNAs as well as the proteins were evaluated in the tumor and blood of 20 patients by real-time quantitative PCR and immunohistochemistry, respectively. The expression of mir15a and bcl-2 proteins in the tumors was not associated with each other or with tumor staging. On the other hand, we found reduced expression of this miRNA in the blood of patients with an advanced stage of OSCC and with lymph node metastasis. The expression of let7a in the tumor and blood was not associated with tumor size, lymph node metastasis, tumor staging and immunoexpression of ras and c-myc proteins. In conclusion, the present study shows that reduced expression of mir15a is associated with OSCC staging.

Identification of epidermal growth factor receptor (EGFR) exon 20 single nucleotide polymorphism in Chinese squamous cell carcinoma of head and neck (SCCHN)

CONCLUSION

The 78th single nucleotide polymorphism (SNP) in exon 20 of epidermal growth factor receptor (EGFR) might be a predictor of the clinical course of squamous cell carcinoma of the head and neck (SCCHN), and genetic predisposition could influence the progression of SCCHN in Chinese subjects.

OBJECTIVE

To analyze the clinical significance of EGFR SNP in Chinese SCCHN patients.

MATERIALS AND METHODS

Direct sequencing of exons 18-21 was used to analyze somatic mutations of EGFR. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to evaluate the expression level of EGFR. The chi-square test and Kaplan-Meier method were the main statistical methods used to analyze the correlation of the investigated variables and prognostic significance.

RESULTS

In analyzing exons 18-21 of EGFR in 96 patients with SCCHN, only one SNP was found in the 78th site of exon 20 and it mostly existed in specimens coming from the hypopharynx. Further statistical analysis showed that among the clinical or histopathologic parameters, the 78th SNP had a close relationship with earlier stage and more localized primary carcinoma, while at present the analysis did not support the proposition that the SNP was an independent prognostic factor.

Multiple head and neck tumours and their genetic relationship

Second primary tumours represent one of the major causes of failure in the treatment of head and neck cancer. Advances in early diagnosis and treatment have improved the patient's disease-specific survival. However, the increase in the occurrence of second primary tumours negatively influences the patient's chance of long-term survival. To understand the molecular events underlying the appearance of head and neck multiple tumours, the clinical history has been evaluated in 2 patients both of whom developed 3 primary tumours of the head and neck. To establish the genetic relationship between the different head and neck cancers which had developed in these 2 patients, loss of heterozygosity was investigated using microsatellite markers located on chromosomes 3p, 9p, 11q, 13q, and 17p. These markers were selected as they frequently demonstrate loss of heterozygosity in head and neck cancer. The following markers were used: D3S1234, D3S1300, D9S170, D11S490, and D17S158. Primer sequences were obtained from the genome database for all of these markers. The third tumour that developed in the first patient, 13 years after the primary, showed loss of heterozygosity on chromosome 17p (in the locus for the gene TP53), which was not present in the previous tumours. All tumours in the second patient showed heterozygosity of chromosome 11 at the locus D11S490. These 2 cases show that multiple tumours can be derived from a genetic alteration of a subclone from previous tumours or from an independent preneoplastic cell clone present in the head and neck mucosa.

Transgenic mice expressing constitutively active Akt in oral epithelium validate KLFA as a potential biomarker of head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a common human neoplasia, of poor prognosis and survival, which frequently displays Akt overactivation. Previously, we reported that mice expressing high levels of constitutively Akt activity (myrAkt) in oral epithelia develop lesions and tumors in the oral cavity.

MATERIALS AND METHODS

Functional genomics of primary keratinocytes from different transgenic mouse lines and immunostaining of mouse and human samples were performed in order to identify and validate putative biomarkers of oral cancer progression.

RESULTS

The expression of KLF4 was found to be increased only in tumor prone samples from mice bearing overactivation of Akt. Such increased expression was confirmed in oral dysplasias and tumors arising in those mice. Tissue microarray analysis of human samples confirmed the association between active Akt and increased KLF4 expression.

CONCLUSION

These data support the notion that KLF4 is potentially a reliable marker of HNSCC, and that myrAkt transgenic mice are valuable tools for preclinical research of HNSCC.

Histological significance of p53 gene expression in squamous cell carcinoma of the buccal mucosa

INTRODUCTION

Oral Squamous Cell Carcinoma (SCC) results from genetic mutations which activate the oncogenes and inactivate the tumor suppressor gene namely TP53. Despite the use of multimodality treatments the prognosis of oral SCC has not changed significantly.

PURPOSE

To evaluate 1) if there is any correlation between the two prognostic indicators i.e. p53 over expression and histological grade of the tumor 2) if any of the parameters of histological grading correlate significantly with p53 over expression. This information would help in understanding the exact role of TP53 gene mutation in cellular progression of oral SCC.

METHOD

Study was conducted on 90 resected specimens of Stage IV SCC of buccal mucosa. Slides from these specimens were evaluated for histological grading by Anneroth's method and p53 over expression by Immunohistochemistry.

RESULTS

Statistically significant co-relation was seen between the total histological grade and p53 over expression. Also 4 individual histological parameters which indicated high cellular turnover were also significantly associated with p53 over expression.

CONCLUSION

TP53 mutation histologically signifies an early event in cellular progression of oral SCC.

Oral carcinoma epidemiology in Paraná State, Southern Brazil

Oral carcinoma is the sixth most frequent type of cancer in the world and the seventh most common in Brazil (the country with the highest incidence in Latin America). Mean five-year survival remains one of the lowest among the main cancers, thus justifying studies that contribute to the development of preventive strategies. The aim of this study was to compare the epidemiological, clinical, and histological characteristics of 91 patients with oral carcinoma. Mean age was 58.62 +/- 10.46 years, and male-to-female ratio was 6.6:1.0 (79 men and 12 women). European descendants predominated with 79 patients (86.8%). Eighty-five individuals (93.4%) smoked and 70 (76.9%) consumed alcohol regularly. Anatomical distribution of tumors was: 27 (29.7%) tongue; 18 (19.8%) floor of mouth; 11 (12.1%) oropharynx; and 11 (12.1%) oral mucosa. Fifty-seven patients (62.6%) presented lymph node involvement and three (3.3%) had distant metastases. Surgery and radiotherapy were used in 43.2% of patients. With the exception of the male/female ratio (which was higher), our data are consistent with previous studies on oral carcinoma patients.

A review of risk factors and genetic alterations in head and neck carcinogenesis and implications for current and future approaches to treatment

Head and neck cancer is the fifth most common cancer worldwide but the most common malignant disease site in central Asia. The treatment of head and neck cancer is one of the most challenging in clinical oncology because of the high content of hypoxic cells of the cancer which increases resistance to therapy and also because of the high capacity of the cancer to regrow during treatment. For unresectable tumours, radiotherapy and chemotherapy alone or more often in combination is the treatment of choice. The aim of this paper is to review current understanding of carcinogenesis of head and neck cancer in relation to predisposing risk factors in general and for specific sub-sites and how these risk factors interact with the main reported genetic alterations in the progression of the cancer. The implications of these changes in determining choice of therapy are also discussed from a brief historical perspective of the various treatment approaches of head and neck cancer.

Novel susceptibility loci for second primary tumors/recurrence in head and neck cancer patients: large-scale evaluation of genetic variants

This study was aimed to identify novel susceptibility variants for second primary tumor (SPT) or recurrence in curatively treated early-stage head and neck squamous cell carcinoma (HNSCC) patients. We constructed a custom chip containing a comprehensive panel of 9,645 chromosomal and mitochondrial single nucleotide polymorphisms (SNP) representing 998 cancer-related genes selected by a systematic prioritization schema. Using this chip, we genotyped 150 early-stage HNSCC patients with and 300 matched patients without SPT/recurrence from a prospectively conducted randomized trial and assessed the association of these SNPs with risk of SPT/recurrence. Individually, six chromosomal SNPs and seven mitochondrial SNPs were significantly associated with risk of SPT/recurrence after adjustment for multiple comparisons. A strong gene-dosage effect was observed when these SNPs were combined, as evidenced by a progressively increasing SPT/recurrence risk as the number of unfavorable genotypes increased (P for trend < 1.00 x 10(-20)). Several polygenic analyses suggest an important role of interconnected functional network and gene-gene interaction in modulating SPT/recurrence. Furthermore, incorporation of these genetic markers into a multivariate model improved significantly the discriminatory ability over the models containing only clinical and epidemiologic variables. This is the first large-scale systematic evaluation of germ-line genetic variants for their roles in HNSCC SPT/recurrence. The study identified several promising susceptibility loci and showed the cumulative effect of multiple risk loci in HNSCC SPT/recurrence. Furthermore, this study underscores the importance of incorporating germ-line genetic variation data with clinical and risk factor data in constructing prediction models for clinical outcomes.

Molecular biology: an early detector of oral cancers

Oral cancers have been one of the leading causes of deaths particularly in the developing countries. Prime reason for this high mortality and morbidity is attributed to the delay in diagnosis and prompt treatment. Relentless research in the field of oncology has led to advent of novel procedures for the early detection of oral cancers. Molecular biology is highly promising in this regard. It is a procedure that detects alterations at a molecular level much before they are seen under a microscope and much before clinical changes occur. Molecular studies serve as basis by which we will eventually be able not only to augment clinical assessment and classification of oral lesions but also predict malignant potential of oral lesions, thus reducing incidence and increasing the scope for early diagnosis and treatment of oral cancers. However, making such sophisticated tools available for the common man in developing countries is one of the most important challenges faced today.

Grading systems in head and neck dysplasia: their prognostic value, weaknesses and utility

BACKGROUND

Grading of dysplasia, including head and neck lesions, continues to be a hotly debated subject. It is subjective and lacks intra- and inter-observer reproducibility due to the insufficiency of validated morphological criteria and the biological nature of dysplasia. Moreover, due to the absence of a consensus, several systems are currently employed.

OBJECTIVES

The aims of this review are to: 1) Highlight the significance of dysplasia and the importance of a valid method for assessing precursor lesions of the head and neck. 2) Review the different histopathological classification systems for grading intraepithelial lesions of the head and neck. 3) Discuss and review quality requirements for these grading systems.

CONCLUSION

Regarding the different classification systems, data concerning the WHO classification system are the most available in current literature. There is no simple relationship or overlapping between the classification systems. Further studies should be done to see whether other systems have advantages above the current WHO system and to discover indications that could lead to an universal classification system for intraepithelial lesions of the head and neck.

MYC gene amplification reveals clinical association with head and neck squamous cell carcinoma in Indian patients

BACKGROUND

Amplification of the MYC gene is reported to be associated with the development of head and neck squamous cell carcinoma (HNSCC). This study is focused to analyze the correlation between MYC gene amplification and various clinicopathological features and outcome in a cohort of 49 dysplastic and 187 primary head and neck lesions.

METHODS

MYC gene amplification was assessed by differential polymerase chain reaction using primer sets from the MYC gene as target locus and DRD2 gene as the control locus.

RESULT

The MYC gene amplification was detected in a total of 23.7% (56/236) head and neck lesions comprising 14.2% (7/49) dysplastic lesions and 26% (49/187) HNSCC samples. The clinicopathological association study between MYC gene amplification with the different clinical parameters like sex, tumor stage, tumor differentiation, lymph node status, tobacco habit and HPV 16/18 status determined significant association of MYC amplification with tumor progression (P = 0.009). Kaplan Meier analysis revealed MYC gene has no prognostic significance on survival in HNSCC.

CONCLUSION

In conclusion, our results suggest that MYC gene amplification is associated with tumor progression in HNSCC.

Alterations of ROBO1/DUTT1 and ROBO2 loci in early dysplastic lesions of head and neck: clinical and prognostic implications

Deletion of chromosomal 3p12.3 was suggested to be associated with dysplastic lesions of head and neck. This region harbors two candidate tumor suppressors ROBO1/DUTT1, ROBO2 and two non-coding RNAs (ncRNAs) located at intron 2 of ROBO1/DUTT1. Aim of this study is to understand the role of these genes in development of head and neck squamous cell carcinoma. A collection of 72 dysplastic lesions and 116 HNSCC samples and two oral cancer cell lines were analyzed for ROBO1/DUTT1 and ROBO2 deletion and promoter methylation. ROBO1/DUTT1, ROBO2 and two ncRNAs mRNA expression were analyzed by Q-PCR. Immunohistochemical analysis of ROBO1/DUTT1 and ROBO2 was performed. Alterations of these genes were correlated with different clinicopathological parameters. High frequency of molecular alterations (deletion/methylation) was seen in ROBO1/DUTT1 than ROBO2. In mild dysplastic lesions both of these genes showed high molecular alterations and remained more or less constant in subsequent stages. Q-PCR analysis showed reduced expression of these genes and the two ncRNAs. In vitro demethylation experiment by 5-aza-dC showed upregulation of ROBO1/DUTT1 and ROBO2 while the expression of the ncRNAs remained unchanged. Immunohistochemical analysis of ROBO1/DUTT1 and ROBO2 showed concordance with their mRNA expression and molecular alterations. Poor patients' outcome was predicted in the cases with alteration of ROBO1/DUTT1 along with tobacco addiction and nodal involvement. Our data suggests (a) ROBO1/DUTT1 and the ncRNAs are transcribed from different promoters, and (b) inactivation of ROBO1/DUTT1 could be used as molecular signature for early detection and prognosis of the head and neck cancer.

SH3GL2 and CDKN2A/2B loci are independently altered in early dysplastic lesions of head and neck: correlation with HPV infection and tobacco habit

To understand the association of candidate tumour suppressor genes SH3GL2, p16(INK4a), p14(ARF), and p15(INK4b) in the pathogenesis of head and neck squamous cell carcinoma (HNSCC), we studied the deletion, mutation, and methylation of these genes in 61 dysplastic lesions and 94 HNSCC samples. In mild dysplasia, SH3GL2, p16(INK4a), and p14(ARF) showed a higher frequency of overall alterations (60-70%) than in p15(INK4b) (40%). However, in subsequent stages of tumour progression, the alteration frequency of these genes did not change significantly. One novel mutation in common exon 2 of p16(INK4a)/p14(ARF) and three in exon 9 of SH3GL2 were seen. Concordance was seen in the expression of these genes with their molecular alterations. Deletions of INK4A-ARF and p15(INK4b) have a significant poor patient outcome. The alterations of p16(INK4a), p14(ARF), and p15(INK4b) were positively correlated with tobacco and inversely with HPV, while SH3GL2 alterations were independent of these factors. Based on aetiological factors, four tumour subtypes were recognized: HPV(-)tobacco(-) (I), HPV(+)tobacco(-) (II), HPV(-)tobacco(+) (III), and HPV(+)tobacco(+) (IV). Groups III and IV showed a high frequency of p16(INK4a)/p14(ARF)/p15(INK4b) alterations with significant poor patient outcome in comparison to group II. Our findings suggest that deregulation of SH3GL2-associated signalling and p16(INK4a)/p14(ARF)/p15(INK4b)-mediated G1-S/G2-M checkpoints of cell cycle are independent pathways for the development of early dysplastic lesions of the head and neck.

Akt activation synergizes with Trp53 loss in oral epithelium to produce a novel mouse model for head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common human neoplasia with poor prognosis and survival that frequently displays Akt overactivation. Here we show that mice displaying constitutive Akt activity (myrAkt) in combination with Trp53 loss in stratified epithelia develop oral cavity tumors that phenocopy human HNSCC. The myrAkt mice develop oral lesions, making it a possible model of human oral dysplasia. The malignant conversion of these lesions, which is hampered due to the induction of premature senescence, is achieved by the subsequent ablation of Trp53 gene in the same cells in vivo. Importantly, mouse oral tumors can be followed by in vivo imaging, show metastatic spreading to regional lymph nodes, and display activation of nuclear factor-kappaB and signal transducer and activator of transcription-3 pathways and decreased transforming growth factor-beta type II receptor expression, thus resembling human counterparts. In addition, malignant conversion is associated with increased number of putative tumor stem cells. These data identify activation of Akt and p53 loss as a major mechanism of oral tumorigenesis in vivo and suggest that blocking these signaling pathways could have therapeutic implications for the management of HNSCC.

DNA copy number variation and loss of heterozygosity in relation to recurrence of and survival from head and neck squamous cell carcinoma: a review

Genetic aberrations, such as DNA copy number variation (CNV) and loss of heterozygosity (LOH), have been implicated in head and neck squamous cell carcinoma (HNSCC) initiation and progression. This review examines CNV and LOH as predictors of HNSCC recurrence and mortality. We searched PubMed for relevant publications and compared and discussed results from the articles. Certain CNV and LOH events have consistently been associated with HNSCC recurrence and survival. The recent high-resolution single nucleotide polymorphism (SNP) arrays have the potential to identify many more genetic changes and concurrent genome-wide CNV, copy-neutral and/or allelic imbalance LOH in HNSCC that may bear on prognosis. Our review confirms that outcome in HNSCC can be predicted to a considerable extent by the presence of tumor cell genetic aberrations. It points out the limitations of some methodologies that were used in the past and discusses the advantages and challenges of using genome-wide SNP arrays.

Pediatric squamous cell carcinoma arising in an alpha-fetoprotein-producing mature cystic teratoma of the mandible

Teratomas, most often diagnosed in younger patients, represent the most frequently identified subtype of pediatric germ cell tumors. It is very uncommon for teratomas to present in the head and neck region and demonstrate malignant transformation. We present a case of squamous cell carcinoma arising in an alpha-fetoprotein-producing cystic teratoma of the mandible in a 2-year-old female that is, to the best of our knowledge, the first such published report. The patient was treated with surgical excision along with chemotherapy and has remained disease-free 2 years after the conclusion of therapy.

Frequent deletion of ING2 locus at 4q35.1 associates with advanced tumor stage in head and neck squamous cell carcinoma

BACKGROUND

Loss of heterozygosity (LOH) in the ING family members has been shown in head and neck squamous cell carcinoma (HNSCC) except for ING2. Like all the other members of ING family, ING2, which is located at chromosome 4q35.1, is a promising tumor suppressor gene (TSG). In this study, we performed LOH analysis of ING2 in HNSCC and compared it with clinicopathological variables.

MATERIALS AND METHODS

We performed LOH analysis in DNAs from 80 paired of normal and HNSCC tissues, using a specifically designed microsatellite marker on chromosome 4q35.1, which detects allelic loss of ING2. TP53 mutation analysis and its relationship with ING2 chromosomal deletion were also performed in available 68 of the samples. The correlation between LOH status and clinicopathological characteristics was evaluated by using statistical methods. The overall survival (OS) and disease free survival (DFS) were also determined.

RESULTS

LOH was detected in 54.6% (30/55) of the informative samples. Statistical significance was obtained between LOH and tumor (T) stage (P = 0.02), application of radiotherapy and chemotherapy. Positive node status (N) appeared to be the only independent prognostic factor for both OS (P = 0.031) and DFS (P = 0.044).

CONCLUSIONS

Our study showed allelic loss of 4q35.1 in HNSCC. The high percentage of LOH suggests ING2 as a candidate TSG in HNSCC. High LOH frequency was statistically associated with advanced T stage, suggesting that ING2 LOH might occur in late stages during HNSCC progression.

Identification of the rare EGFR mutation p.G796S as somatic and germline mutation in white patients with squamous cell carcinoma of the head and neck

BACKGROUND

Somatic mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) are involved in tumorigenesis and response to targeted therapies in distinct cancer types. Squamous cell carcinomas of the head and neck (HNSCC) show an incidence of EGFR mutations varying from 7% in Asians to 0% to 4% in white patients. Mutational screening predominantly focuses on the analysis of hotspot regions of EGFR (exons 19 and 21).

METHODS

In a follow-up study, we screened for mutations in exons 18 to 21 of the EGFR gene in 127 patients.

RESULTS

In this cohort, a mutation frequency of 2.4% (3/127) was detected. In addition to the previously reported mutation p.K745R, the otherwise rare EGFR mutation p.G796S occurred in 2 patients with HNSCC (2/127).

CONCLUSION

EGFR kinase mutations are rare in white patients with HNSCC. Extension of mutational screening to exon 20 may clarify the frequency and impact of the mutation p.G796S.

Alterations of 3p21.31 tumor suppressor genes in head and neck squamous cell carcinoma: Correlation with progression and prognosis

The aim of our study was to analyze the alterations of some candidate tumor suppressor genes (TSGs) viz. LIMD1, LTF, CDC25A, SCOTIN, RASSF1A and CACNA2D2 located in the chromosomal region 3p21.31 associated with the development of early dysplastic lesions of head and neck. In analysis of 72 dysplastic lesions and 116 squamous cell carcinoma of head and neck, both deletion and promoter methylation have been seen in these genes except for CDC25A and SCOTIN where no methylation has been detected. The alteration of LIMD1 was highest (50%) in the mild dysplastic lesions and did not change significantly during progression of tumor indicating its association with this stage of the disease. It was evident that alterations of LTF, CDC25A and CACNA2D2 were associated with development of moderate dysplastic lesions, while alterations in RASSF1A and CACNA2D2 were needed for progression. Novel somatic mutations were seen in exon 1 of LIMD1 (7%), intron 3/exon4 splice junction of LTF (2%) and exon 7 of cdc25A (10%). Quantitative RT-PCR analysis revealed mean reduced expression of the genes in the following order: LTF (67.6 +/- 16.8) > LIMD1 (53.2 +/- 20.1) > CACNA2D2 (23.7 +/- 7.1) > RASSF1A (15.1 +/- 5.6) > CDC25A (5.3 +/- 2.3) > SCOTIN (0.58 +/- 0.54). Immunohistochemical analysis of CDC25A showed its localization both in cytoplasm and nucleus in primary lesions and oral cancer cell lines. In absence of HPV infection, LTF and RASSF1A alterations jointly have adverse impact on survival of tobacco addicted patients. Thus, our data suggested that multiple candidate TSGs in the chromosomal 3p21.31 region were differentially associated with the early dysplastic lesions of head and neck.

Molecular signatures of metastasis in head and neck cancer

BACKGROUND

Metastases are the primary cause of cancer treatment failure and death, yet metastatic mechanisms remain incompletely understood.

METHODS

We studied the molecular basis of head and neck cancer metastasis by transcriptionally profiling 70 samples from 27 patients-matching normal adjacent tissue, primary tumor, and cervical lymph node metastases.

RESULTS

We identified tumor-associated expression signatures common to both primary tumors and metastases. Use of matching metastases revealed an additional 46 dysregulated genes associated solely with head and neck cancer metastasis. However, despite being metastasis-specific in our sample set, these 46 genes are concordant with genes previously discovered in primary tumors that metastasized.

CONCLUSIONS

Although our data and related studies show that most of the metastatic potential appears to be inherent to the primary tumor, they are also consistent with the notion that a limited number of additional clonal changes are necessary to yield the final metastatic cell(s), albeit in a variable temporal order.

Polymorphisms of the DNMT3B gene and risk of squamous cell carcinoma of the head and neck: a case-control study

DNA-methyltransferase-3B (DNMT3B) may play an oncogenic role during tumorigenesis, and its genetic variants have been reportedly to be associated with risk of several cancers, but few studies have investigated their roles in squamous cell carcinoma of the head and neck cancer (SCCHN). Here we report a hospital-based case-control study with 832 SCCHN patients and 843 cancer-free controls of non-Hispanic whites that evaluated the association between two DNMT3B single nucleotide polymorphisms (SNPs) DNMT3B -149C>T (rs2424913) and DNMT3B -579G>T (rs2424909) in the promoter region and risk of SCCHN. We found that compared with C-allele carriers, the DNMT3B -149 TT genotype was statistically significantly associated with increased risk of SCCHN (adjusted OR, 1.35, 95% CI, 1.01-1.80, P=0.043), whereas the DNMT3B -579 TT genotype showed only a non-statistically significant risk compared with G-allele carriers. Further analysis of the effects of combined genotypes suggested that subjects with either DNMT3B -149 TT or DNMT3B -579 TT homozygous genotypes had statistically significantly increased risk of SCCHN (adjusted OR=1.36, 95% CI=1.07-1.73, P=0.013). Stratification analysis showed a more profound risk in the subgroups of the young (< or =57 years, the median age of the controls), males, current smokers, current drinkers, and patients with primary tumor sites of pharynx and larynx. This large study provides reliable risk estimates for associations between DNMT3B variants and SCCHN risk in non-Hispanic whites, and our findings are consistent with that of previously reported cancer case-control studies of other cancers. Further mechanistic studies are needed to unravel the underlying molecular mechanisms.

Cellular mechanisms of tumour suppression by the retinoblastoma gene

The retinoblastoma (RB) tumour suppressor gene is functionally inactivated in a broad range of paediatric and adult cancers, and a plethora of cellular functions and partners have been identified for the RB protein. Data from human tumours and studies from mouse models indicate that loss of RB function contributes to both cancer initiation and progression. However, we still do not know the identity of the cell types in which RB normally prevents cancer initiation in vivo, and the specific functions of RB that suppress distinct aspects of the tumorigenic process are poorly understood.

MicroRNA and oral cancer: future perspectives

MicroRNAs (miRNAs) are small non-coding RNAs that mediate gene expression at the post-transcriptional level by degrading or repressing target messenger RNAs (mRNA). They are about 22 nucleotides in length and regulate mRNA translation by base pairing to partially complementary sites, predominantly in the 3' untranslated region (3' UTR) of mRNA. In this review, we discuss miRNA biogenesis and function, together with its possible involvement in oral cancer. Despite its great importance in normal cell development and diseases, a small number of studies have attempted to investigate miRNA in oral cancer. Overexpression of oncogenic miRNA may reduce protein products of tumor-suppressor genes. On the other hand, loss of tumor-suppressor miRNA expression may cause elevated levels of oncogenic protein. One or both of these alterations could represent new targets for cancer diagnosis and treatment in the future. Many researchers have focused on genetic and epigenetic alterations in oral squamous cell carcinoma cells. The emergence of miRNA knowledge, and its potential interactive action with such alterations, therefore creates a new understanding of cell transformation.

Transforming growth factor beta isoforms (TGF-beta1, TGF-beta2, TGF-beta3) messenger RNA expression in laryngeal cancer

PURPOSE

Cancerogenesis is a multistage process controlled by many cytokines, including growth factors. The aim of the study was the comparison of transcriptional activity of transforming growth factor beta (TGF-beta) genes in laryngeal squamous cell carcinomas and adjacent nonneoplastic tissues.

MATERIALS AND METHODS

Tissues samples were obtained from 32 patients with laryngeal squamous cell carcinoma in histologic grades G1 to G3 who underwent surgical treatment at the ENT Clinics of Medical University of Silesia in Katowice, Poland. Quantification of gene expression was performed by real-time quantitative reverse transcriptase polymerase chain reaction technique.

RESULTS

In tumor cells, expression of TGF-beta1 and TGF-beta2 isoforms (P < .001) was higher than in normal tissues. There was a positive correlation between the expression of TGF-beta1 and TGF-beta2 genes in tumors (R = 0.78, P = .0000) and adjacent normal tissues (R = 0.77, P = .0000).

CONCLUSIONS

The results suggest that TGF-beta1 and TGF-beta2 messenger RNAs may be useful as molecular markers in distinguishing cancer from nonneoplastic tissues in laryngeal area.

Molecular mechanisms of head and neck cancer

Despite advances in understanding the underlying genetics, squamous cell carcinoma of the head and neck (SCCHN) remains a major health risk and one of the leading causes of mortality in the world. Current standards of treatment have significantly improved long-term survival rates of patients, but second tumors and metastases still remain the most frequent cause of high mortality in SCCHN patients. A better understanding of the underlying genetic mechanisms of SCCHN tumorigenesis will help in developing better diagnostics and, hence, better cures. In this article we will briefly outline the current state of diagnostics and treatment and our understanding of the molecular causes of SCCHN.

Alterations in the p53 pathway and their association with radio- and chemosensitivity in head and neck squamous cell carcinoma

Chemotherapy and/or radiotherapy are established measures in treatment protocols of head and neck squamous cell carcinoma (HNSCC). However, we still lack reliable predictive markers for the response to radio- and chemotherapy. The p53 pathway is involved in stress response and thus might influence chemo-/radiosensitivity. Using 29 HNSCC cell lines previously characterized for p53 mutations, we simultaneously analyzed several key players in the p53 pathway by RT-PCR, transcript sequencing and immunohistochemistry, and investigated their association with chemosensitivity and radiosensitivity. Cell lines with p53 mutations were slightly more sensitive to cisplatin than those with wild-type p53. The type of mutation did not influence radio- or chemosensitivity. p14(ARF), an activator of p53, was lost or mutated in all cell lines. Three cell lines showed overexpression of HDM-2, a major negative regulator of p53; however, HDM-2 levels did not correlate with radio- or chemosensitivity. HPV-16 oncoproteins were detected in one highly chemoresistant cell line. Our findings suggest that molecular events resulting in the inactivation of the p53 pathway occur in all HNSCC cell lines. However, single alterations in the p53 pathway are not reliable predictors for the response to radio- or chemotherapy in HNSCC.

Head and neck cancer

Most head and neck cancers are squamous cell carcinomas that develop in the upper aerodigestive epithelium after exposure to carcinogens such as tobacco and alcohol. Human papillomavirus has also been strongly implicated as a causative agent in a subset of these cancers. The complex anatomy and vital physiological role of the tumour-involved structures dictate that the goals of treatment are not only to improve survival outcomes but also to preserve organ function. Major improvements have been accomplished in surgical techniques and radiotherapy delivery. Moreover, systemic therapy including chemotherapy and molecularly targeted agents--namely, the epidermal growth factor receptor inhibitors--has been successfully integrated into potentially curative treatment of locally advanced squamous-cell carcinoma of the head and neck. In deciding which treatment strategy would be suitable for an individual patient, important considerations include expected functional outcomes, ability to tolerate treatment, and comorbid illnesses. The collaboration of many specialties is the key for optimum assessment and decision making. We review the epidemiology, molecular pathogenesis, diagnosis and staging, and the latest multimodal management of squamous cell carcinoma of the head and neck.

OPN/CD44v6 overexpression in laryngeal dysplasia and correlation with clinical outcome

Laryngeal dysplasia is a common clinical concern. Despite major advancements, a significant number of patients with this condition progress to invasive squamous cell carcinoma. Osteopontin (OPN) is a secreted glycoprotein, whose expression is markedly elevated in several types of cancers. We explored OPN as a candidate biomarker for laryngeal dysplasia. To this aim, we examined OPN expression in 82 cases of dysplasia and in hyperplastic and normal tissue samples. OPN expression was elevated in all severe dysplasia samples, but not hyperplastic samples, with respect to matched normal mucosa. OPN expression levels correlated positively with degree of dysplasia (P=0.0094) and negatively with disease-free survival (P<0.0001). OPN expression was paralleled by cell surface reactivity for CD44v6, an OPN functional receptor. CD44v6 expression correlated negatively with disease-free survival, as well (P=0.0007). Taken as a whole, our finding identify OPN and CD44v6 as predictive markers of recurrence or aggressiveness in laryngeal intraepithelial neoplasia, and overall, point out an important signalling complex in the evolution of laryngeal dysplasia.

Mitochondrial mutations are a late event in the progression of head and neck squamous cell cancer

PURPOSE

To determine the timing of mitochondrial mutations in the progression of head and neck squamous cell carcinoma.

EXPERIMENTAL DESIGN

Twenty-three mitochondrial mutations were identified in 12 tumors using a high-throughput mitochondrial sequencing array. Areas of adjacent dysplastic and normal epithelium adjacent to tumors were sequenced using conventional methods for the presence of mutations that occurred in the corresponding tumor.

RESULTS

Two of 23 (8.7%) tumor mitochondrial mutations (2 of 12 tumors) were present in both the areas of adjacent dysplasia and normal epithelium. Five of 23 (21.7%) tumor mitochondrial mutations (4 of 12 tumors) were present in areas of adjacent dysplasia. Eleven of 12 tumors contained nonsynonymous mutations that resulted in protein coding alterations. A significant difference (P < 0.01, chi(2)) was found in the incidence of mitochondrial mutation that occurred after development of cancer compared with adjacent areas dysplasia and normal epithelium.

CONCLUSIONS

The majority of mitochondrial mutations occur during or after the transition of preneoplastic epithelium to cancer in head and neck squamous cell carcinoma, indicating that these are a late event in head and neck carcinogenesis.

[Incidence, latency, and prognosis of local and regional recurrences in patients with upper aerodigestive tract cancer treated by laser microsurgery: influence of initial tumor parameters]

INTRODUCTION

The aim of the present study is to identify clinical factors that influence the incidence and the prognosis of local and regional recurrences.

PATIENTS AND METHODS

The data of 1,426 patients with newly diagnosed squamous cell carcinoma of the upper aerodigestive tract who were treated by curative laser microsurgery between August 1986 and December 2002 were reviewed.

RESULTS

In 381 patients (27%), tumor recurrences were detected during follow-up. The frequency of local as well as regional recurrences significantly correlated with the initial stage of tumors. Recurrences of advanced carcinomas occurred considerably sooner than those of stage II and I cancer. During the 4th year of follow-up, patients with early stage disease had a recurrence rate twice as high as those with advanced carcinomas. Survival with recurrence was adversely affected by adjuvant radiotherapy as part of initial treatment, simultaneous local and regional manifestation of recurrence, male sex, advanced stage of initial disease, and by oral or hypopharyngeal site of the primary tumor.

CONCLUSION

Early carcinomas of the upper aerodigestive tract recur at a lower rate than advanced stage diseases, but after a longer mean latency period. As a consequence, these patients should receive close follow-up also during the 3rd and 4th years after treatment, particularly as the prognosis of their recurrences is most often favorable.

Risk-based and diagnostics-linked personalized medicine for cancer

Personalized medicine is gaining momentum in healthcare by allowing physicians to determine an individual’s predisposition to different diseases and to better diagnose and treat those diseases. Personalized medicine is frequently described as the right drug for the right patient at the right time; that is, a physician will prescribe treatment based on the individual characteristics of each patient such that the patient is likely to respond to a particular treatment with minimal adverse events. The heterogeneity of cancer makes the implementation of personalized medicine a necessity.

Fragile Histidine Triad Expression in Oral Squamous Cell Carcinoma and Precursor Lesions

PURPOSE

Fragile histidine triad (FHIT) expression in precursor oral lesions (POL) and oral squamous cell carcinomas (OSCC) was studied with regard to (a) the frequency of loss of FHIT expression, (b) whether loss of FHIT expression correlates with degree of dysplasia in POLs, (c) whether FHIT loss predicts high-risk POLs that are more likely to transform, and (d) whether FHIT loss in OSCCs correlates with survival.

EXPERIMENTAL DESIGN

Ninety-four POLs and 86 OSCCs were immunostained for FHIT. Survival analysis was done for cases with validated clinical outcomes.

RESULTS

By optimizing the immunostaining protocol, we found that FHIT is expressed in a distinctive strong nuclear and weak cytoplasmic pattern in oral tissues. Loss of FHIT expression was found in 42 of 94 (45%) POLs and in 66 of 86 (77%) OSCCs. We observed a statistically significant positive correlation between frequency of FHIT loss and increasing grade of dysplasia (chi2=13.8; degrees of freedom=4; P=0.008). Loss of FHIT expression in POLs that progressed to malignancy was more frequent than in those that did not [17 of 25 (68%) versus 12 of 29 (41.4%), respectively]. This difference was statistically significant (chi2=3.8; degrees of freedom=1; P=0.046). In OSCCs, loss of FHIT staining indicated a worse prognosis (survival rate, 36.2%) than when positive FHIT staining was observed (survival rate, 50%), but the difference was not statistically significant (P=0.546, Kaplan-Meier, log-rank).

CONCLUSIONS

FHIT seems to localize to both nuclear and cytoplasmic domains. FHIT inactivation occurs early in oral carcinogenesis and may be useful molecular marker for progressive dysplastic oral lesions.

Prostate cancer stem cells: a target for new therapies

Prostate cancer is now a common disease in men over 50 years of age. Medical therapies for prostate cancer are based on discoveries from the mid-twentieth century, and in the long term are rarely curative. Most treatments are directed towards an androgen receptor-expressing, highly proliferative target cell, which does indeed form the vast majority of cells in a prostate tumour. However, by invoking the existence of a cancer stem cell which, like normal epithelial stem cells in the prostate, does not express androgen receptor and is relatively quiescent, the observed resistance to most medical therapies can be explained. The phenotype of the prostate cancer stem cells is that of a basal cell and cultures derived from cancers, but not benign tissues, express a range of prostate cancer-associated RNAs. Furthermore, stem cells purified on the basis of alpha2beta1 high integrin and CD133 cell surface antigen expression, from an established culture of Gleason 4 (2+2) prostate cancer (P4E6), were able to form multiple intraprostatic tumours in nude mice when grafted orthotopically in a matrigel plug containing human prostatic stroma. The final tumours reexpressed androgen receptor and displayed a histology similar to that of a Gleason 4 cancer.