Squamous carcinoma of the head and neck: molecular mechanisms and potential biomarkers

Relevance of infection with human papillomavirus: the role of the p53 tumor suppressor protein and E6/E7 zinc finger proteins (Review)

Human papillomaviruses (HPV) are small circular, double-stranded DNA viruses infecting epithelial tissues. HPV types can be classified both as high-risk or low-risk. Of the more than 120 different identified types of HPV, the majority are involved in infections of the genital tract, cancer of the cervix, vulva, vagina and penis, and of non-anogenital localizations, such as the head and neck areas. From the point of view of the infection, human papillomaviruses have developed several molecular mechanisms to enable infected cells to suppress apoptosis. This review provides a comprehensive and critical summary of the current literature that focuses on cervical carcinoma and cancer of the head and neck caused by HPV. In particular, we discuss HPV virology, the molecular mechanisms of carcinogenesis, the role of the tumor suppressor protein p53 and the E6/E7 zinc finger proteins. Classification of HPV according to diagnosis is also described.

Piroxicam selectively inhibits the growth of premalignant and malignant human oral cell lines by limiting their progression through the S phase and reducing the levels of cyclins and AP-1

Studies have shown that nonsteroidal antiinflammatory drugs (NSAIDs) reduce the risk of and mortality from a variety of cancers. Although cyclooxygenase (COX)-dependent and -independent pathways may be involved, the mechanisms responsible for these effects remain unknown. In our study, we found that piroxicam inhibited cell growth in premalignant and malignant, but not normal, human oral epithelial cell lines in a concentration- and time-dependent manner. After 6 days of exposure, the concentration that inhibited growth by 50% was 181 and 211 microM for premalignant and malignant cells, respectively. Piroxicam did not induce apoptosis. The growth inhibitory effect was COX and PGE2 independent. Adding PGE2 or infecting cells with a COX-1 transgene did not abrogate piroxicam-induced growth inhibition. After treatment of the premalignant and malignant cell lines with piroxicam, cells accumulated in the S phase of the cell cycle. Upon removal of piroxicam, cells entered the G2 phase. The S phase block was accompanied by a reduction in the protein levels of cyclin A, cyclin B1, cyclin D1, cdc2, PCNA and the c-jun AP-1 component. Therefore, piroxicam may exert its growth inhibitory effects selectively on the premalignant and malignant human oral epithelial cells lines via signaling pathways regulating the progression of cells through the S phase of the cell cycle.

An ex vivo study exploring the diagnostic potential of 1H magnetic resonance spectroscopy in squamous cell carcinoma of the head and neck region

BACKGROUND

Definitive diagnosis of head and neck cancer is generally made by histopathologic evaluation. Management and prognosis largely depend on accurate and timely diagnosis. We have explored the use of (1)H magnetic resonance spectroscopy in search of a better or complementary diagnostic technique.

METHODS

Tumor and adjacent normal tissue specimens (n = 135) from untreated head and neck cancer patients (n = 40) were obtained and subjected to spectroscopic evaluation followed by histopathologic analysis. Data were partitioned into training and test sets and subjected to multivariate analysis.

RESULTS

The resonances from taurine, choline, glutamic acid, lactic acid, and lipid were found to have diagnostic potential by our optimal region selection algorithm. Multivariate analysis of the spectral data differentiated between normal and malignant tissues, with an overall accuracy of 92.6% (training set, 97.3%; test set, 87.3%), an overall sensitivity of 93% (test set, 90%), and an overall specificity of 92% (test set, 82.6%).

CONCLUSIONS

(1)H magnetic resonance spectroscopy combined with multivariate methods of analysis can distinguish between normal and malignant squamous cell tissue, and this may lead to the development of an objective and noninvasive diagnostic procedure.

Gene expression profiling of advanced head and neck squamous cell carcinomas and two squamous cell carcinoma cell lines under radio/chemotherapy using cDNA arrays

BACKGROUND AND PURPOSE

The response of squamous cell carcinomas of the head and neck (HNSCC) to radio/chemotherapy is accompanied by complex changes in patterns of gene expression. It is highly probable that a better understanding of molecular and genetic changes can help to optimize the treatment of HNSCC. cDNA arrays provide a powerful tool for high-throughput monitoring of gene expression in small clinical specimens.

MATERIALS AND METHODS

We used tumour biopsies from four patients with HNSCC which have been taken prior to and during radio/chemotherapy. The patterns of gene expression obtained from clinical samples were compared with gene expression profiles of two squamous cell carcinoma cell lines (FaDU and UD-7A).

RESULTS

The experimental data analysis revealed changes in expression levels of several genes during radio/chemotherapy. Despite treatment, independent samples taken from the same cell line or tumour in situ were more similar to each other than either was to other specimens. The data indicate a high gene heterogeneity of HNSCC that is preserved during treatment.

CONCLUSIONS

From our preliminary results we conclude that the cDNA array experimental approach can detect differences in gene expression between treated and untreated small tumour biopsies, as well as inter-individual differences in expression profiles between HNSCC tumours. The examination of a greater sample size will be needed to make this preliminary evaluation useful to elucidate the functional significance of individual genes which exhibit altered levels of expression under radiation therapy.