Markers of Oral Lichen Planus Malignant Transformation

Figure 2

The relationship of p53, MDM2, and SUMO-1 in apoptosis regulation. MDM2 induces p53 ubiquitination and its proteasomal degradation, acting as an E3 ubiquitin ligase; the decrease in p53 level will lead to an inhibition of apoptosis. Under normal conditions, SUMO-1 regulates MDM2 level: MDM2 is undergoing self-ubiquitination and proteasomal degradation; DNA damage leads to SUMO-1 binding MDM2 and blocking its self-ubiquitination, conducting to an increase in MDM2 ubiquitin ligase activity towards p53. While p53 acts by inducing transcription of p53AIF-1, PUMA, BID, and NOXA, leading to the induction of apoptosis, reducing p53 levels by MDM2- and SUMO-1-conjugated action will lead to inhibition of apoptosis.