History of Research on Phospholipid Metabolism and Applications to the Detection, Diagnosis, and Treatment of Cancer

In the past 30 years there has been a significant increase in the number of publications on phospholipid (PL) metabolism, both for the medical purposes of detection and diagnosis of cancer and for the monitoring of the treatment of human cancers. Most of the work has focused on the pathway that produces phosphatidylcholine, the major component of human cell membranes. The trigger for this research was the advent of applications of NMR spectroscopy in vitro and in vivo in the 1980’s and observations that most cancer cells and tumors had significant increases in the water-soluble PL precursors and breakdown products. Increased phosphocholine (PC) has been focused on as a marker for cancer using Magnetic Resonance Spectroscopy (MRS) and Positron Emission Tomography (PET). MRS is now used clinically to aid in the diagnosis and severity of some brain tumors; and choline PET is used for the diagnosis and staging of recurrent prostate cancer, paid for by medical insurance companies. Another major area of research starting in the 1990’s was the development of specific choline kinase (CK) inhibitors aimed at the isoenzyme CK-a. This isoenzyme is markedly upregulated in cancer cells and unexpectedly was found to have a role in oncogenic transformation independent of its enzyme function.