Involvement of centrosomes in nuclear irregularity of thyroid carcinoma cells.

Nuclear irregularities including nuclear pseudoinclusions and nuclear grooves are characteristic of papillary thyroid carcinoma cells and are regarded as important diagnostic clues in histopathology. We observed nuclear features of thyroid carcinoma cell lines (KTC-1 and TPC-1) in various culture conditions and performed immunocytochemical examinations for cytoskeleton molecules to clarify the morphogenesis of thyroid carcinoma nuclei. We found that nuclear irregularities presenting as bean-like nuclei (BLNs) and donut-like nuclei (DLNs) appeared in cells from confluent cultures, but not in cells from sparse cultures. On immunocytofluorescence analyses, clusters of gamma-tubulin, representing a centrosome, frequently localized at the indentation of BLNs or in the hole of DLNs of thyroid carcinoma cells. In conclusion, we suggest that cell-to-cell contact may affect nuclear changes such as BLNs and DLNs in cancer cell lines and that centrosomes may be involved in the morphogenetic process of these nuclear changes.