Endocrine Abstracts

Background: Papillary thyroid carcinoma (PTC) is known as the most common histological subtype of thyroid carcinoma. The prognosis of PTC is generally favorable. However, small number of patients with PTC progressed with distant metastasis and invasion to adjacent organs. New diagnostic tool for early detection of PTC with poor outcome is desired. We previously reported that autoantibody to WD repeat domain 1 (AWA) in the serum was associated with the existence of undifferentiated thyroid carcinoma (UTC) and PTC (Izawa S et al., Clin Endocrinol 2013). The objective of our study is todevelop this assay to be sensitive and specific for differentiating PTC with poor prognosis.

Materials and methods: A peptide library (peptide length = 12 aa, off-set = 6 aa) originated from human WDR1 isoform 1 were firstly screened (1st screening) by the serum of 3 patients with UTC and 3 normal healthy controls (N). Furthermore, 2nd screening was performed for selecting candidate peptides by using another peptide library (peptide length = 12 aa, off-set = 2 aa) designed by the result of 1st screening. Finally, candidate peptides were evaluated to be hydrophilic by bioinformatics. Sera from 16 patients with advanced thyroid carcinoma (UTC and PTC with metastasis and/or invasion to adjacent organs), 8 with not advanced PTC (without metastasis and invasions to adjacent organs), 14 with benign thyroid nodules (B), 15 with autoimmune thyroid disease (A), and 7 N were evaluated by ELISA using 12 candidate peptides.

Results: A total number of 42 peptides for detecting high titer of AWA were selected by the 1st screening. Most of these peptides were located in the C terminal of WDR1 isoform 1. After finishing 2nd screening, 12 candidate peptides with hydrophilic sequences were selected for ELISA. A peptide originating from human WDR1 isoform 1 (WDR1 2–33) presented significantly higher (P < 0.05) titer of AWA in advanced thyroid carcinoma (0.621 ± 0.289) than not advanced PTC (0.326 ± 0.114), B (0.255 ± 0.142), A (0.318 ± 0.164), and N (0.303 ± 0.161). The diagnostic performance of WDR1 2–33 was superior to other 11 peptides by ROC analysis.

Conclusion: We demonstrated that WDR1 2–33 could be a peptide containing the epitope of AWA. Our data suggested that evaluating AWA by WDR1 2–33 might be a new diagnostic method for early diagnosis of PTC with poor prognosis (patent pending JP2018–045806).