Frequent allelic loss of 21q11.1∼q21.1 region in advanced stage oral squamous cell carcinoma

Evidence for loss of heterozygosity (LOH) at chromosomes 9p and 17p in oral granular cell tumors: a pilot study

OBJECTIVE

The objective of this study was to assess loss of heterozygosity (LOH) in tumor suppressor gene loci in oral granular cell tumors (GCTs).

STUDY DESIGN

We assessed LOH in 8 samples of oral GCT using polymorphic microsatellite markers at chromosome regions 3p, 9p, 11q, and 17p, flanking areas close to tumor suppressor genes. We further performed immunohistochemistry to detect the p53 and Ki-67 proteins and associated these expressions with the molecular results.

RESULTS

Five samples showed LOH in 3 markers at chromosomes 9p and 17p (markers P53, AFM238WF2 and D9S162) with fraction of allelic loss of 42.8% for each of these markers. No LOH was identified in any other chromosome. LOH was not associated with the immunohistochemical expression of p53 and Ki-67.

CONCLUSIONS

The present study shows LOH at chromosomes 9p and 17p in oral GCTs.

Gene expression in uninvolved oral mucosa of OSCC patients facilitates identification of markers predictive of OSCC outcomes

Oral and oropharyngeal squamous cell carcinomas (OSCC) are among the most common cancers worldwide, with approximately 60% 5-yr survival rate. To identify potential markers for disease progression, we used Affymetrix U133 plus 2.0 arrays to examine the gene expression profiles of 167 primary tumor samples from OSCC patients, 58 uninvolved oral mucosae from OSCC patients and 45 normal oral mucosae from patients without oral cancer, all enrolled at one of the three University of Washington-affiliated medical centers between 2003 to 2008. We found 2,596 probe sets differentially expressed between 167 tumor samples and 45 normal samples. Among 2,596 probe sets, 71 were significantly and consistently up- or down-regulated in the comparison between normal samples and uninvolved oral samples and between uninvolved oral samples and tumor samples. Cox regression analyses showed that 20 of the 71 probe sets were significantly associated with progression-free survival. The risk score for each patient was calculated from coefficients of a Cox model incorporating these 20 probe sets. The hazard ratio (HR) associated with each unit change in the risk score adjusting for age, gender, tumor stage, and high-risk HPV status was 2.7 (95% CI: 2.0–3.8, p = 8.8E-10). The risk scores in an independent dataset of 74 OSCC patients from the MD Anderson Cancer Center was also significantly associated with progression-free survival independent of age, gender, and tumor stage (HR 1.6, 95% CI: 1.1–2.2, p = 0.008). Gene Set Enrichment Analysis showed that the most prominent biological pathway represented by the 71 probe sets was the Integrin cell surface interactions pathway. In conclusion, we identified 71 probe sets in which dysregulation occurred in both uninvolved oral mucosal and cancer samples. Dysregulation of 20 of the 71 probe sets was associated with progression-free survival and was validated in an independent dataset.

Genetics/epigenetics of oral premalignancy: current status and future research

Squamous cell carcinoma (SCC) of the oral and oropharyngeal region is the sixth most common malignancy in the world today. Despite numerous advances in treatment, long-term survival from this disease remains poor. Early detection can decrease both morbidity and mortality associated with this neoplasm. However, screening for potentially malignant disease is typically confounded by difficulty in discriminating between reactive/inflammatory lesions vs those lesions that are premalignant in nature. Furthermore, the histologic diagnosis of dysplasia can be subjective and is thus prone to a considerable range of interpretation. Similarly, no definitive, validated criteria exist for predicting which dysplastic lesions are most likely to progress to cancer over time. Given this state of science, the presence of dysplasia can only be used to indicate that an oral lesion may have an increased risk of malignant transformation. Molecular biomarkers capable of identifying the subset of lesions likely to progress to cancer are required to eliminate this clinical diagnostic dilemma. The purpose of this review is to assess the current state of knowledge regarding genetic/epigenetic alterations observed in oral mucosal premalignancy. In addition, recommendations for future research studies directed at defining the predictive capacity of specific biomarkers in this modeling are presented.

Advances in the biology of oral cancer

The incidence of oral cancer remains high and is associated with many deaths in both Western and Asian countries. Several risk factors for the development of oral cancer are now well known, including smoking, drinking and consumption of smokeless tobacco products. Genetic predisposition to oral cancer has been found in certain cases but its components are not yet entirely clear. In accordance with the multi-step theory of carcinogenesis, the natural history of oral cancer seems to gradually evolve through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. A number of genomic lesions accompany this transformation and a wealth of related results has appeared in recent literature and is being summarized here. Furthermore, several key genes have been implicated, especially well-known tumor suppressors like the cyclin-dependent kinase inhibitors, TP53 and RB1 and oncogenes like the cyclin family, EGFR and ras. Viral infections, particularly with oncogenic HPV subtypes and EBV, can have a tumorigenic effect on oral epithelia and their role is discussed, along with potential therapeutic interventions. A brief explanatory theoretical model of oral carcinogenesis is provided and potential avenues for further research are highlighted.

Aspects of digestive tract tumors in Down syndrome: a literature review

The purpose of this study was to describe the digestive neoplasms found in persons with Down syndrome. Due to intellectual disability, persons with Down syndrome do not convey their symptoms and pain, leading to delayed diagnosis and potentially worse outcome. It is thus important to know which organs are at risk for tumors and possible tumor risk factors. In a review of the literature, we found 13 benign tumors and 127 cancers in 1 fetus, 8 children, and 131 adults with Down syndrome. The review suggests a decreased incidence of digestive cancer, however, with a possible increased incidence of neoplasms of the pancreas and gallbladder. The distribution of cancers is distinct from that in the general population and that in persons with other intellectual disabilities who share the same life conditions, suggesting that constitutional protective factors exist. This review may allow a more specific, adapted medical follow-up for persons with Down syndrome and could help to elucidate the oncogenesis of digestive neoplasms.