Abstract: Carboxypeptidase E(CPE)is a key carboxypeptidase,and it is involved in the biosynthesis of peptide hormones and neurotransmitters.CPE as a prohormone processing enzyme expressed in different cancer types was analyzed the data in the GEO profile database.Elevated CPE mRNA expression was found in neuroendocrine tumors in lung and pituitary adenomas.Microarray studies demonstrated that significantly elevated levels of CPE mRNA was found in many metastatic non-endocrine cancers(colon rectal,renal cancers and Ewing sarcomas),whereas expression of CPE mRNA was absent in their respective counterpart normal tissues.Not only wild-type CPE was expressed in tumors,but a variant was correlated with tumor behavior.In very large or invasive tumors,the copy numbers of the variant of CPE mRNA were very high.On the whole,CPE may play an important role in promoting tumor growth,invasion and metastasis.CPE could be used potentially as a diagnostic and prognostic biomarker for metastasis in different cancer types.