Abstract

PTEN (phosphatase and tensin homolog deleted on chromosome ten) also referred to as MMAC (mutated in multiple advanced cancers) was discovered as a tumor suppressor gene and later found to be a phospholipid phosphatase. PTEN negatively regulates Akt activation by preventing its phosphorylation. PTEN therefore inhibits the PI 3-kinase/Akt signaling pathway which is important for cell growth and survival. Overexpression or enhanced activation of PTEN can potentially impair injury healing by at least 4 mechanisms. PTEN can: 1) inhibit entry into the cell cycle by inhibiting G1 to S phase progression and arrest cell proliferation required for tissue reconstruction during injury healing; 2) increase apoptosis by blocking Akt activation leading to increased Bad and Caspase-9 activities; 3) inhibit hypoxia-induced angiogenesis required for injury healing by blocking Akt-mediated VEGF gene transcription; 4) inhibit Akt-mediated cell migration, i.e. re-epithelialization, which is also required for injury healing. The same mechanisms can also suppress cancer growth and metastases. Therefore, elucidating the role of the PTEN/PI 3-kinase/Akt pathway will likely advance our knowledge of the mechanisms controlling the processes of injury healing and cancer growth.