Post-translational modifications of albumin in cancer a rich source for diagnostic and monitoring of treatment

Abstract

Albumin is in contact with all cells in a body. This major protein in a plasma accesses all tissues and organs and has a number of different roles. Albumin was found to have more than 50 post-translational modifications (PTMs). Some of the albumin PTMs showed correlation with tumorigenesis. Examples of PTMs of albumin are reported at www.phosphosite.org. Modifications like glycation of patients with breast cancer is seen higher as compared to healthy control. We hypothesize that several novel post-translational modification in albumin could be related to cancer and can be used as biomarkers. We performed mass spectrometry and 2D gel electrophoresis analysis of serum albumin for 32 most common PTMs. We identified most of these PTMs in albumin. We observed that human cancer cells affected PTMs profile of albumin. Examples of affected PTMs are phosphorylation, palmitolylation, geranyl- geranylation etc. We observed also differences in PTMs profiles of albumin from serum of a healthy person and cancer patient. O - GlcNAcylation, farnesylation, glutathionylation , S- nitrosylation etc PTMs were found to differ. Our data show that PTMs of albumin can be easily detected. Our trial with 32 PTMs can be expanded to detect up to a hundred known PTMs. These PTMs may correlate with cancer development, and may be used as markers in cancer diagnostic and prognostic.