Direct progression of capsular invasive carcinomas from subcapsular focal hyperplasias induced by hypothyroidism-mediated tumor promotion in a rat two-stage thyroid carcinogenesis model.
J Cancer Res Clin Oncol 2012;
139:395-401. [PMID:
23114882 DOI:
10.1007/s00432-012-1338-4]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Accepted: 10/11/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE
Some goitrogens promote thyroid carcinogenesis in rats in an initiation-promotion model; this model frequently produces carcinomas that invade fibrously thickened capsules, termed capsular invasive carcinomas (CICs). The present study tested a hypothesis that CICs originate from parenchymal proliferative lesions located beneath the capsule.
METHODS
Cell proliferation activity, cell-cycle kinetics and cellular invasion were immunohistochemically examined in subcapsular proliferative lesions in male F344 rats treated with an anti-thyroid agent, propylthiouracil or sulfadimethoxine, during the tumor-promotion phase after initiation with N-bis(2-hydroxypropyl)nitrosamine.
RESULTS
Focal follicular cell hyperplasias (FFCHs) were the most commonly observed parenchymal proliferative lesions. Subcapsular FFCHs located near CICs showed more Ki-67(+) cells in the capsular side than the contrary parenchymal center side. Most of these FFCHs located near CICs showed accumulated immunoreactivity for cyclin A, cyclin D, cyclin E and cyclin-dependent kinase-2, whereas most subcapsular FFCHs located elsewhere did not show such accumulated expression of cell-cycle molecules. Subcapsular FFCHs immunoreactive at the capsular front for tenascin-C, a tumor invasion marker of extracellular matrix protein, showed high proliferation activity.
CONCLUSIONS
Subcapsular FFCH-forming cells can potentially spread directly into the fibrously thickened capsule to form CICs by accelerating cell-cycle activity.
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