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The knowledge of the biology of head and neck squamous cell carcinoma (HNSCC) has had relatively little impact on the improvement in oncologic outcome up to date. However, the identification of oncogenes and tumor suppressor genes (TSGs) involved in cancer progression contributes to the understanding of the molecular pathways involved in oncogenesis and could contribute to individual risk assessment and provide tools for improvement of treatment and targets for therapy based on the alterations in these pathways. The aim of this article is to review the chromosomal aberrations commonly found in HNSCC, to identify the genes in these chromosomal regions suggested to act as (candidate) oncogenes or TSGs, and to discuss the molecular mechanisms modulating their expression.

Squamous cell carcinoma of the head and neck (HNSCC) most frequently arise in the epithelial tissues of the upper aerodigestive tract. Patients with HNSCC, aged <45 years are categorized as young adults (YA). They are characterized by more severe form of this disease and often lack of classical, causative risk factors (tobacco smoking, alcohol abusing) in comparison to older (typical) patients (OP). The study purpose was to establish an anticipated protective role of DNA repair genes polymorphisms against cancer-causing agents. It was assumed that the polymorphisms in these genes may have a significant role in the etiology of HNSCC in YA. Studies were carried out on three groups: YA group with HNSCC (n = 90), young healthy group without cancer (YH, n = 160) and OP with HNSCC (n = 205). Three polymorphisms in DNA repair genes were analyzed: XPD ex23: A35931C, XRCC1 ex10: G28152A, and XRCC3 ex7: C18067T. The choice of these genes was connected with their involvement in three different DNA repair pathways. Genotyping was carried out by polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) technique. Statistical analysis included: calculation of odds ratio (ORs), 95 % confidence intervals (CIs) and p value. There was no significant difference in the distribution of XPD genotypes in YA compared to OP or YH. The XRCC1 AA genotype variant was observed less frequently in HNSCC YA (4.7 %) than in YH and in OP group (17.1 and 10.8 %, respectively). XRCC3 CT genotype variant was observed more frequently in HNSCC YA (61.8 %) than in YH (36.3 %) and this result is statistically significant. This variant was associated with the borderline increased risk of HNSCC development in an early age, however, a similar tendency was not observed in case of double mutated TT variant. The established differences of genotypes distribution do not seem to differentiate substantially YA and OP in head and neck cancer risk.

Patients with squamous cell carcinoma of the head and neck (HNSCC) aged less than 45 years are categorized as young adults (YA) and in opinion of many authors in comparison to older (typical) patients (OP) are characterized with more serious form of the disease and often lack the classical risk factors associated with the illness. Hence, there is a need of an exact clinical analysis and a search for additional causative factors. The purpose of this study was to estimate the role of genetic factors in the etiology of HNSCC in YA. Studies carried out on 60 patients of the study group (YA) and 72 older control patients were directed to: (1) a degree of spontaneous and induced chromosome breaks estimated by bleomycin test, (2) a degree of spontaneous and induced DNA damage and a potential of DNA repair determined by comet assay and (3) polymorphism of genes of glutathione transferases M1 and T1, responsible for detoxification of metabolites of carcinogens of tobacco smoke, studied by PCR-based genotyping. The level of chromosome breaks (spontaneous and induced), the level of DNA damage (spontaneous and induced), DNA repair potential and the distribution of polymorphic variants of GSTT1 gene are not significantly different in YA and in OP, which suggests that these factors do not appear the causative factors for HNSCC in young age. The significant risk factor of HNSCC in YA may be GSTM1 null genotype, which may cause the defective detoxification of metabolites of polycyclic aromatic hydrocarbons of tobacco smoke.

Cyclin D1 is one of the key proteins involved in cell cycle control, and it is believed that its overexpression may be connected with tumorigenesis. A reason for cyclin D1 deregulation may be connected to a common G870A polymorphism at codon 242 in exon 4 of the CCND1 gene. This single nucleotide substitution, localized in the conserved splice donor site between exon 4 and the intron 4 boundary, might modulate the frequency of alternative splicing. It has been postulated that the A allele results in a higher level of mRNA (transcript b) encoding a protein with an altered C-terminal domain. The influence of CCND1 G-->A polymorphism for the risk of cancer and the prognosis of patients with different types of solid tumors has already been suggested. This study was conducted to investigate the association between the cyclin D1 gene polymorphism and laryngeal cancer risk, as well as the clinical outcome. We also examined the relationship between genotype/allele distributions and the cyclin D1 expression profile. The genotyping study was done using the PCR-RFLP method in 63 patients with larynx cancer and 102 healthy controls. The heterozygotic genotype GA as well as a combination of GA and AA genotypes were associated with an increased risk of larynx cancer compared to the GG genotype (OR =3.02; P =0.004 and OR =2.52; P =0.013, respectively). The A allele frequency was higher in cancer cases (0.484) than in controls (0.416) that were connected with a slightly increased risk of cancer development (OR =1.34); however, the difference was not significant. The AA genotype was associated with an early cancer onset compared to the GG genotype (median age: 51.5 and 63.0 years, respectively). We also demonstrated that the AA genotype was associated with the occurrence of lymph node metastases (OR =3.26) and a higher level of cyclin D1 overexpression. These results suggest that the CCND1 A allele may be a genetic factor that modulates the risk of larynx cancer development, and it may also have an effect on tumor biology and disease prognosis.

Cell lines provide a good model for studies on molecular and cellular events accompanying neoplastic transformation and cancer progression. The data in recent literature suggest an occurrence of repetitive chromosome aberrations that can be linked with particular stages of cancer. Ten cell lines derived from squamous cell carcinoma of the larynx at the University of Turku were karyotyped. The studied cell lines represented a variety of primary locations of the tumors, TNM staging and histological grading. Karyotyping was done by the classical cytogenetic technique with the application of GTG, QFQ and other banding techniques; some complex aberrations were analyzed by the FISH technique. The results document several numerical and structural aberrations. Attention was focused on the monosomy of chromosomes 13, 17 and 18, frequent deletions of the Y chromosome. Structural aberrations were frequently seen at chromosomes 1, 3, 4, 7, 8, 9 and 11, mostly as deletions (usually deletions of a whole arm), translocations, isochromosomes, duplications and marker chromosomes. The study is in progress and aims to find a correlation between particular aberrations and disease staging. At present, two observations seem to be firm: the amplification of the 11q13 region appeared in tumors with a short survival. However, the primary location of the tumor should be taken into account when considering 11q13 as a prognostic marker. The same is applicable for del(9p), which indicates an early stage of disease. Besides the frequent chromosome aberrations, attention should be paid to marker chromosomes that are potentially specific for laryngeal cancer.

Epidemiological studies have confirmed the correlation between tobacco smoking, environmental pollution and the incidence of cancers of the respiratory tract. The occurrence of laryngeal cancer in Poland is relatively high compared to other European countries. Since 1969 the mortality related to larynx cancer appears to be increasing. Tobacco smoke contains an abundance of such carcinogenic compounds as polycyclic aromatic hydrocarbons (PAH), aromatic amines and N-nitrosoamines, which can react with DNA and form adducts. We analyzed aromatic DNA adducts in laryngeal tissues from patients with primary laryngeal, which was confirmed histopathologically to be squamous cell carcinoma. The group consisted of 33 patients (5 women and 28 men). Total laryngectomy was performed in patients. A detergentphenol method was used for DNA isolation. Aromatic DNA adducts were analyzed by a 32P-postlabelling technique with butanol extraction and high performance liquid chromatography. The presence of aromatic DNA adducts was demonstrated in all tissues. Large interindividual differences of DNA adduct levels were seen in each tissue studied. There was a higher mean level of DNA adducts in interarytenoid area non-tumors (51.96/10(8) +/- 91.71 NN) than in non-tumor tissue elsewhere (46.91/10(8) +/- 46.36 NN) and tumor tissue (43.52/10(8) +/- 45.88 NN). Adduct levels were correlated with age, sex, cigarette smoking and TNM stage.

The p53 gene is known as an anti-oncogene that manifests its function by controlling the cell cycle and is responsible for apoptosis of cells with unrepaired DNA. An accelerated p53 protein synthesis is the first response of a cell following DNA damage. However, mutations of the p53 gene can disturb protein synthesis or may be responsible for synthesis of a changed protein unable to control the cell cycle. Laryngeal tissue specimens from 120 patients were tested by immunohistopathological staining to detect mutated wild-type p53 protein. It was found that p53-positive specimens correlated with TNM staging and histopathological grading. Another indication of entering the cell cycle and undertaking an active proliferation by laryngeal cells was shown by detection of proliferating cell nuclear antigen (PCNA) and Ki67 nuclear antigen, which appeared in proliferating cells (late G1, S-G2 and M phase), but was absent in resting cells. Scoring of the staining for p53 protein, PCNA and Ki67 correlated with each other. DNA from 40 specimens was then isolated, amplified by polymerase chain reaction and analysed by single-strand conformation polymorphism and DNA sequencing for mutation in the p53 gene. Fifteen DNA samples were found to be positive, while mutations were detected in exons 5-8 in 13 samples. The majority of mutations were found in tissue specimens from T3 and T4 tumors. A possible explanation is almost half was attributable to genotoxic effects of tobacco smoking. Changes in the p53 gene and its products may also reflect early changes in laryngeal carcinogenesis and be of prognostic value.