Pre-analytical-related variability influencing serum peptide profiles demonstrated in a mass spectrometry-based search for colorectal and prostate cancer biomarkers.

Author(s): Karczmarski J, Rubel T, Mikula M, Wolski J, Rutkowski A, Zagorowicz E, Dadlez M, Ostrowski J

Publication: Acta Biochim Pol, 2013, Vol. 60, Page 417-25

PubMed ID: 24046818 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of clotting time, fasting, preparation for colonoscopy, and cancer on the levels of peptides in serum from 16 colorectal and 28 prostate cancer patients and from 86 healthy individuals. Only 12 specimens were used for the clotting study, 15 for the fasting study and 56 for the colonoscopy preparation study. Prior to colonoscopy, patients were treated with polyethylene glycol and underwent a phosphate enema. Unless otherwise noted, blood was allowed to clot at room temperature for 60 min before centrifugation. Specimens from patients with colorectal cancer were collected before any treatments, but prostate cancer patients were diagnosed 2-10 years prior to the study and had received treatments including prostatectomy, radiation therapy, or hormonal therapy. Progression of cancer was noted in 15 of the 28 prostate cancer patients. All serum was stored at -80 degrees C.

   Summary of Findings:

   When the blood specimens were centrifuged after 2 h of clotting time instead of 1 h, increases in the levels of 2 peptides and decreases in the levels of 4 peptides that make up the fibrinopeptide A ladder were observed. While none of these changes distinguished between serum from healthy individuals and those with prostate cancer (with or without progression), levels of one of the 6 peptides susceptible to clotting time were higher in serum from colorectal cancer patients than in serum from healthy individuals. There was no effect of fasting on levels of the peptides in the entire dataset or of peptide components of apolipoprotein A4 (APOA4). In contrast, significant differences (>2 fold, p<0.01) in the levels of 67 peptides (of 1373) were observed between the 30 specimens from healthy individuals taken prior to colonoscopy and the 26 obtained from other healthy individuals 4 weeks after colonoscopy. 49 of the peptides affected by colonoscopy were from APOA4. A total of 118 and 88 peptides were differentially expressed (>2 fold, p<0.01) between serum from healthy individuals and those with progressing prostate and colorectal cancer, respectively, with 37 peptides in common. Further, 30 peptides were observed that distinguished between progressing prostate and colorectal cancer, but only 2 of these distinguished serum from cancer patients versus healthy individuals. No differences were observed between serum from patients with non-progressing prostate cancer and healthy individuals.

   Biospecimens

   • Bodily Fluid - Serum
   • Bodily Fluid - Blood

   Preservative Types

   • Frozen

   Diagnoses:

   • Neoplastic - Carcinoma
   • Normal

   Platform:

   Analyte	Technology Platform
   Peptide	LC-ESI-MS/MS

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Diagnosis/ patient condition	Healthy Prostate cancer Colorectal cancer
   Biospecimen Acquisition	Time of biospecimen collection	After 12 h fast 2 h after eating Immediately prior to colonoscopy 4 weeks after colonoscopy
   Storage	Time at room temperature	1 h 2 h
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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