Cyclooxygenase-2: A Role in Cancer Stem Cell Survival and Repopulation of Cancer Cells during Therapy

Figure 1

Prostaglandin E2 biosynthesis and downstream cellular effects. Arachidonic acid is released from cellular membranes and converted to PGH₂ through the activity of the COX enzymes. COX-1 is constitutively expressed in many cells, generating low levels of prostaglandins that are cytoprotective and maintain homeostasis. In contrast, COX-2 is absent from most cells and is induced by a number of inflammatory stimuli. PGH₂ is rapidly converted to PGE₂, which plays a predominant role in cancer progression by stimulating tumour cell proliferation, migration, angiogenesis, apoptosis resistance, invasion, and metastasis. NSAIDS and COXIBS can pharmacologically block the activity of the COX enzymes.