Analysis of albumin fatty acid binding capacity in patients with benign and malignant colorectal diseases using electron spin resonance (ESR) spectroscopy

In colorectal cancer (CRC), no biological marker is known that could serve both as a marker for detection and prognosis. Electron spin resonance (ESR) spectroscopy of spin-labeled fatty acid (FA) molecules binding to human serum albumin is a suitable method for the detection of conformational changes and alterations of transport function of albumin through changes in its FA binding capabilities. The aim of this study was to examine whether the FA binding to albumin is detectably and significantly altered in CRC patients when compared with patients having benign colorectal diseases. One hundred four patients operatively or endoscopically treated for CRC, sigmoid diverticulitis, or a colorectal adenoma were examined before procedure. Albumin was analyzed by ESR with spin-labeled FA. A determination ratio (DR) was calculated from the measured ESR spectra as ratios of the fraction of FA that is tightly bound vs. the fractions that are loosely interacting with albumin or are unbound. Patients with CRC showed significantly lower DR values (DR, -0.09 +/- 0.98 vs. 0.61 +/- 1.43) than patients with benign colorectal diseases, consistent with a change of conformation and transport function of albumin in CRC. Within the CRC group, with advanced tumor stage, the difference in DR values increased. ESR of FA binding to albumin thus seems to be suitable for detection of patients with CRC. Furthermore, a correlation with advanced tumor stage can be established. These results suggest that a further evaluation of the role of ESR in patients with all stages of CRC should take place. It should also be examined whether ESR might play a role in detecting CRC in a larger panel of patients.