title: E-cadherin expression and cell proliferation in the primary tumor and metastatic lymph nodes of papillary thyroid microcarcinoma.
abstract: Although papillary thyroid microcarcinoma (PTMC) has an excellent prognosis, certain cases exhibit aggressive clinical manifestations. In this study, we assessed the expression of E-cadherin and Ki-67 in primary PTMC tumors and metastatic lymph nodes, in order to investigate the mechanism underlying the mainly indolent but potentially malignant nature of PTMC. A total of 93 PTMC patients treated in our institute were included in this study. All primary tumors and 57 metastatic lymph nodes were immunohistochemically stained and a total of 73 tumors (78.5%) were positive for E-cadherin. E-cadherin expression was significantly less common at the invasive front (58.1%, P<0.01) compared to that at the center of the tumor. Tumors that had lost E-cadherin expression at the invasive front frequently presented with lymph node metastasis (70.6%). Small tumors (≤5 mm diameter) expressed E-cadherin significantly more frequently compared with larger tumors (P=0.04); however, no other particular characteristic was found to correlate with the status of E-cadherin expression in the primary tumors. E-cadherin expression was detected in 49 (86.0%) of the 57 metastatic foci and correlated significantly with the expression status at the invasive front of the tumor (P=0.02). The Ki-67 index was universally low and was not correlated with the clinicopathological characteristics or the E-cadherin expression of the tumors. These results suggested that cancer cells in the metastatic lymph nodes exhibit indolent characteristics, similar to those of the primary PTMC. However, the metastatic cancer cells may have already completed the process of epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET), suggesting an innate malignant potential.
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Naoyoshi
authors.initials: N
authors.lastname: Onoda
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Noda
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kashiwagi
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Aomatsu
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Kurata
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Hidemi
authors.initials: H
authors.lastname: Kawajiri
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Takashima
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
authors.forename: Kosei
authors.initials: K
authors.lastname: Hirakawa
keywords: E-cadherin; epithelial-to-mesenchymal transition; lymph node metastasis; mesenchymal-to-epithelial transition; papillary thyroid microcarcinoma