Osteopontin Levels in Patients with Papillary Thyroid Cancer According to the Presence of Hashimoto’s Thyroiditis

Background: Human papillary thyroid carcinoma (PTC) is often associated with Hashimoto’s thyroiditis(HT); their coexistence improves PTC prognosis. Osteopontin, a secreted glycoprotein, plays a role in cellsurvival, immunity, and tumor progression, its expression being associated with a poor prognosis and metastasisin several malignancies. Osteopontin overexpression correlates with aggressive clinicopathological features inPTC. Lymph node metastases and large tumor size positively correlate with osteopontin positivity. This studyaimed to: (1) confirm osteopontin overexpression in human PTC samples; (2) compare osteopontin expressionlevels in PTC cases with and without HT; and (3) identify correlations between tumor aggressiveness andosteopontin expression levels. Materials and
Methods: Plasma osteopontin was assessed in 45 patients withPTC, 22 patients with PTC and HT, and 24 healthy controls by enzyme-linked immunosorbent assay. Thyroidtissue osteopontin mRNA and protein levels were analyzed by reverse transcription-polymerase chain reactionand Western blotting, respectively.
Results: Plasma osteopontin levels were significantly higher in PTC patientsthan in healthy controls. Plasma osteopontin, tissue osteopontin mRNA, and tissue osteopontin protein levelswere significantly lower in patients with PTC and HT than in those with PTC alone. In advanced disease stagecases, osteopontin mRNA and protein expression levels were lower in patients with PTC and HT than in thosewith PTC alone. However, the osteopontin expression level was not significantly associated with the TNMstage.
Conclusions: Plasma osteopontin, tissue osteopontin mRNA, and tissue osteopontin protein levels weresignificantly lower in patients with PTC and HT than in those with PTC alone, suggesting that HT attenuatesPTC aggressiveness through negative regulation of osteopontin expression.