Figure 1.

Carcinogenesis of the Cervix

HPV-infected cervical cells express viral oncoproteins, E6 and E7. E6 oncoprotein (the militia man) binds the tumor suppressor protein, p53 (the police officer), resulting in its degradation. It also stimulates the hypoxia-inducible factor 1 (HIF-1) transcription factor, an innate hypoxic stress response in normal cells that binds to p53 to induce apoptosis. Because p53 is largely degraded, HIF-1 stimulates the formation of new blood vessels (the supply pipeline), which in turn provide the growing tumor cells with a blood supply. On the other hand, the E7 oncoprotein (the militia leader) binds the “pocket domains” of pRb protein (the corrupt politician), which interrupts the interaction between pRb protein and E2F family transcription factors (the worker), resulting in their release in their transcriptionally active form and leading to cell-cycle activation and a malignant transformation.