PTGS2 and malignant colon neoplasm: In various human malignancies, including colon cancer, the overexpression of COX-2 is associated with enhanced biosynthesis of PGE2, further sustained by the downregulation of hydroxyprostaglandin dehydrogenase 15-(NAD) (HPGD; also known as 15-PGDH) involved in the metabolism of PGE2 to less biological active products [7,8].