Cell Cycle Regulatory Mechanisms in Head and Neck Squamous Cell Carcinoma

Regulation of cellular proliferation and programmed cell death is essential for a normal growth and differentiation of cells and tissues. Disturbing the fine balances of these processes, as a result of genetic or biochemical abnormalities, may have serious consequences for the organism in terms of disease states, including neoplasia. This chapter focuses on the various molecular mechanisms that regulate cell proliferation and cell death in head and neck squamous cell carcinoma HNSCC, and how the disruption of regulatory pathways plays a role in tumor development and progression. Progression through the cell cycle is driven by the assembly and disassembly of a series of protein kinase complexes, which phosphorylate their substrates on specific serine and threonine residues. These enzyme complexes consist of a catalytic subunit, the cyclin-dependent kinase, a regulatory cyclin subunit; and proliferating cell nuclear antigen. Loss of expression of cell-cycle inhibitors in cancer makes these suitable candidates for gene replacement strategies.