Human Papillomavirus and Head and Neck Cancer
Head and Neck Squamous Cell Carcinoma (HNSCC) is a major cause of morbidity and mortality in the United States. Although HNSCC is a disease mainly attributed to tobacco and alcohol use, 15-20% of these patients has no such exposure history, suggesting that other factors might causally associated with a similar phenotype in this subgroup of patients. There is strong molecular evidence that “high-risk” types of Human Papillomavirus (HPV) play a crucial role in the pathogenesis of Head and Neck Squamous Cell Carcinoma in individuals without alcohol or tobacco history.
In this project, using the cervical cancer model as a paradigm, we are exploring the role of HPV16 in HPV16-positive HNSCC. We are trying to answer the following question: Does repression of E6 and E7 gene expression result in reactivation of p53 and pRb tumor suppressor pathways and reversion of malignant phenotype of HPV16+ Head and Neck Cancer cells? If this is the case, we will be able to demonstrate a close etiologic association between HPV and subset of HNSCC. In order to answer this question we have to accomplish the following specific aims:
- To repress HPV16 E6/E7 oncogene expression in HPV16+, oropharyngeal carcinoma cell lines using hairpin RNAs against HPV16 E6, E7.
- To examine the effects of E6/E7 oncogene repression in the growth rate of HPV16+ oropharyngeal cancer cell lines.
- To carry out biochemical analysis to determine whether E6 and E7 are repressed.
- To carry out biochemical analysis to determine whether there is reactivation of tumor suppressor pathways (p53 and pRb)
This project is also attempting to answer the very important questions of the association between HPV and a subset of patients with HNSCC. For almost two decades numerous trials have shown the presence of HPV DNA in tumors or serum in a subset of HNSCC. However, the most important question as to whether HPV initiates and maintains the malignant conversion and whether repression of these oncogenes would reverse the malignant phenotype and cause growth arrest have not been answered. In the project, we will attempt to give definitive answers to these questions.
A Genome Wide Look at DNA Methylation Patterns in Head and Neck Cancer
Cancer is a genetic disease of the cell. We have a large body of knowledge concerning both structural and functional genetic alterations present in cancerous cells but little is known about the inherited epigenetic alterations found in tumors. In large part this is due to the lack of technologies that enable a genome wide look at epigenetic features. Recently, a group of investigators lead by Dr. Paul Lizardi has succeeded in setting up a technology that enables the genome wide mapping of hypo and hypermethylation of DNA. Methylation of CpG islands in promoter regions of “cancer genes” is an example of epigenetic modification known to play a role in the pathogenesis of cancer.
Head and Neck Cancer has been chosen as the first application of this novel technology that enables a genome wide look at DNA methylation patterns. A DNA array containing 320,000 probes reports on the methylation status of the DNA sequences in the vicinity of the probed site. Analysis of 30 paired normal and tumor tissues shows highly significant and reproducible differences that are specific to the tumor tissue. We have also uncovered significant differences between the methylation profiles of subjects that are tumor bearing when compared to non tumor bearing normal volunteers.
It is very likely that novel markers for the diagnosis, classification and prognosis of head and neck squamous cell cancer will be discovered and put to use for the benefit of patients afflicted with this disease.
Immunotherapy for Head and Neck Squamous Cell Carcinoma Utilizing Tumor Antigen-loaded Nanoparticles
Loading dendritic cells (DCs) with Tumor antigens (TAs) encapsulated within nanoparticles (NPs), is an efficient and effective method for cross-presentation and stimulation of cell-mediated immunity. Aims include: a) Fabrication of NPs and b) Measurement of efficiency of DCs to present to and activate autologous T-cells in vitro, compared with that achieved by a soluble antigen-driven system. Ability to effect killing of autologous tumor cells will be assessed using a 2-color fluorescence assay.