Final answer:
Epithelial cells infected by HPV express the viral protein E6 that binds to and inhibits the tumor suppressor protein p53, preventing DNA damage repair and apoptosis, and allowing for unchecked cell growth and mutation accumulation.
Step-by-step explanation:
Epithelial cells are the primary targets for infection by certain types of human papillomavirus (HPV), which can lead to cervical cancer. The virus produces proteins like E6, which have a significant impact on the function of host cellular proteins. Specifically, when HPV enters the epithelial cells, E6 binds to a crucial tumor suppressor protein called p53. This binding has a detrimental effect on p53 activity.
In a healthy cell, p53 acts as a genome guardian that detects DNA damage and can either halt the cell cycle for DNA repair or trigger apoptosis to eliminate the damaged cell. However, when E6 binds p53, this function is neutralized, leading to an impairment in apoptosis and allowing the cells to proliferate unchecked, even with DNA mutations present. Over time, these mutations can accumulate, resulting in the development of cancerous cells and the potential for invasive cervical cancer as depicted in Figure 27.16.
Examination of cervical cells via a Pap smear can reveal changes in the cells' appearance, such as increased size and the presence of multiple nuclei, indicating HPV infection and potential transformation as shown in Figures 7.4 and 4.4.