Dissertation committee:
Γεώργιος Κ. Ζωγράφος, Καθηγητής, Ιατρική, ΕΚΠΑ
Μανούσος Μ. Κωνσταντουλάκης, Καθηγητής, Ιατρική, ΕΚΠΑ
Γεώργιος Ε. Θεοδωρόπουλος, Αναπληρωτής Καθηγητής , Ιατρική, ΕΚΠΑ
Νικόλαος Αλεξάκης, Αναπληρωτής Καθηγητής, Ιατρική, ΕΚΠΑ
Κωνσταντίνος Γ. Τούτουζας, Αναπληρωτής Καθηγητής, Ιατρική, ΕΚΠΑ
Δημήτριος Θεοδώρου, Αναπληρωτής Καθηγητής, Ιατρική, ΕΚΠΑ
Δημήτριος Τραφαλής, Επίκουρος Καθηγητής, Ιατρική, ΕΚΠΑ
Summary:
Introduction
Τhe designation of pleiotropic cytokines OPG, RANKL, TRAIL as orchestrators of tumor microenvironment provides the rationale for pursuing their potential involvement in the milieu of papillary thyroid carcinoma (PTC). The integration of signaling transduction cascades induced by OPG, RANKL, TRAIL with mutations of KRas protein, overexpression of c-Fos oncoprotein, and mutations as well as overexpression of tumor-suppressor p53 protein delineates a nuanced and sophisticated network implicated in genesis and progression of cancer. The present study investigates for the first time the hypothesis that the immunohistochemical expression of RANKL, OPG, TRAIL, p53, KRas, and c-Fos configures a subpopulation of PTC with aggressive biological behavior. Secondary scope of our study was to explore the clinicopathological profile of PTC with a propensity to metastasize to central lymph node compartment.
Patients‒Methods
The present study enrolled 114 patients who underwent total thyroidectomy with simultaneous dissection of lymph nodes of central cervical compartment from 2009 to 2014. Inclusion criterion was the diagnosis of histologically confirmed papillary thyroid carcinoma (PTC). The expression of RANKL, OPG, TRAIL, p53, KRas, c-Fos was evaluated immunohistochemically in total PTC as well as according to histological PTC subtype. The immunohistochemical (IHC) expression of the under investigation molecules was explored in correlation with adverse clinicopathological characteristics, such as age older than 45 years old (according to AJCC/TNM 7th edition), male sex, histological subtype, multifocality, stage disease (AJCC/TNM 7th edition), central lymph node metastases (CLNM) status, as well as with coexistence of Hashimoto’s thyroiditis (HT). Putative associations of expressions of the under investigation molecules with presence of CLNM were analyzed applying multivariable-adjusted logistic regression models controlling for age, sex and T stage (AJCC/TNM 7th edition). Moreover, the correlation of pairs of coexpressions of examined molecules with CLNM status was analyzed in total PTC. Finally, the association of the clinicopathological characteristics of study population with presence of CLNM was explored.
Results
RANKL, OPG, TRAIL, KRas, c-Fos, and p53 IHC expression was demonstrated in 78.6%, 63.2%, 61.4%, 47.4% 73.7% , and 7% of PTC, respectively. The IHC expression of RANKL, OPG and TRAIL showed significant association with CLNM (p=0.007, p<0.001, and p=0.002, respectively). Additionally, the OPG IHC expression correlated significantly with multifocality (p=0.045). The association of RANKL and OPG IHC expressions with CLNM proved to be significant as regards classical PTC (c PTC) (p=0.027 and p=0.006, respectively). TRAIL IHC expression associated significantly with CLNM in both c PTC (p=0.043) and follicular variant of PTC (FVPTC) (p=0.049). Multivariable-adjusted logistic regression models controlling for age, sex and T stage revealed a significant correlation of TRAIL IHC expression with CLNM (OR:10.335, 95% CI: 1.23-86.87). Six pairs of IHC coexpressions of the examined molecules demonstrated a significant correlation with CLNM: TRAIL–KRas (p=0.011), TRAIL–c-Fos (p=0.006), OPG–c-Fos (p=0.024), RANKL–TRAIL (p<0.001), RANKL–0PG (p<0.001), TRAIL–OPG (p<0.001). p53, KRas and c-Fos IHC expressions showed no significant association with any of the investigated characteristics. IHC expression of KRas protein, reflecting the presence of KRas mutation, was observed in 50% of FVPTC. A novel finding of our study is the IHC expression of KRas protein in almost half of PTC (47.4%), in particular in 47.4% of c PTC and 33.3% of TCV PTC. Importantly, in the context of KRas-expressing PTC, the c PTC constitutes the most prevalent subtype (66.7%), while FVPTC represented only 29.6% of total PTC. Finally, the capsular invasion and the stage Τ3 (AJCC/TNM 7th edition) reflecting herein the minimal extrathyroidal extension were correlated significantly with the presence of CLNM (p=0.019, p=0.006, respectively).
Conclusions
Further research is mandatory for clinical translation of the novel findings of the present study that designate the cytokines OPG, RANKL, TRAIL as crucial players of the metastatic potential of PTC not only per se but also in concert with KRas mutations and c-Fos overexpression. Likewise, deciphering the role of the capsular invasion and the minimal extrathyroidal extension in the metastatic potential of PTC remains an appealing realm of research. The establishment of prognostic biomarkers will revolutionize the individualization the prophylactic central lymph node dissection in PTC.
Keywords:
Papillary thyroid carcinoma, Lymph node metastases, Molecular biomarkers, OPG, RANKL, TRAIL, p53, KRas, c-Fos
