Polyamine oxidase activity and polyamine levels in human colorectal cancer and in normal surrounding mucosa

Background: polyamine oxidase (PAO) is an enzyme involved in the interconversion pathway of polyamines, compounds required for cell proliferation and differentiation. As the role of PAO in tumor growth is unclear, and no data about PAO activity in human colorectal carcinoma are available, our aim was to investigate PAO activity and polyamine levels in this kind of tumor. Methods: Polyamine levels and PAO activity were detected in 30 neoplastic colorectal samples and surrounding mucosa by HPLC. Results: Free and N-1-acetylated polyamine levels were higher in the neoplastic tissue than surrounding mucosa of the same patient. On the contrary, PAO activity was significantly lower in the neoplastic tissue than surrounding mucosa. Conclusion: it seems that PAO activity does not play an important role in the increased free polyamine levels in human colorectal carcinoma. Instead, the low PAO activity observed in our study let us to hypothesize that polyamine analogues can have an antitumoral effect on colorectal carcinoma.