Identification of a peptide autoimmune marker for lung cancer Free

LB-154

We have used the Invitrogen ProtoArray(TM) to identify potential autoantigens for distinguishing lung cancer patients from normal individuals and those with benign lung conditions. A set of identical arrays was tested with patient sera to find which of approximately 5000 recombinant human proteins bound IgG from sera of cancer patients but not the others. One protein, which showed high signals with sera from cancer patients, but low signals for sera from non-cancer patients is a form of Cyclin E2 identified by Genbank assession BC007015.1. Another form of Cyclin E2 on the array, identified by Genbank assession BC020729.1 showed little reactivity with any of the samples. These two forms of Cyclin E2 differ in the C-terminal 37 amino acids. We obtained two peptides based on this C-terminal sequence: E2-1, CEEVNYINTFRKGGQLSPVCNGGIMTPPKSTEKPPGKH (the full sequence, with an N-terminal cysteine added as a specific linker), and E2-2: CNGGIMTPPKSTEKPPGKH (the final 19 amino acids, including the constituent cysteine). These peptides were individually coupled to maleimide activated bovine serum albumin which was used to coat Luminex(TM) SeroMap(TM) beadsets. A third beadset was coated with the recombinant Cyclin E2 form BC007015.1. These reagents were used with the Luminex100(TM) analyzer to test 234 serum samples from patients over 50 years of age (87 lung cancer, 77 normal, 70 benign) and the results were subjected to Receiver Operator Curve analysis. Areas Under the Curve of 0.81, 0.69 and 0.73 were determined for peptides E2-1, E2-2 and the recombinant protein respectively. A biomarker panel comprising proteins and peptides as well as autoantibodies against defined autoantigens offers improved performance over either class of biomarkers alone.