Alterations of the tumor suppressor gene p53 are detected with high frequency in undifferentiated thyroid carcinomas while are very rare in differentiated thyroid neoplasms. Impairment of p53 function may be responsible for loss of differentiation and acquisition of an aggressive biological behaviour by thyroid tumors. Aim of the study was to evaluate the effects of restoration of wild type p53 activity on cell growth and differentiation of an anaplastic thyroid carcinoma cell line (ARO), characterized by the presence of a mutated p53. ARO cell clones were generated by stable transfection with a temperature-sensitive mutant p53 which exhibited wild type-like properties at 32oC, but was inactive at 37oC. When grown at 32oC, cell clones expressing exogenous p53, as assessed by indirect immunofluorescence, showed a significant reduction of cell proliferation rate (?40%), as compared to controls transfected with vector alone. Inhibition of cell growth was characterized by an increase of cells accumulating in the G1 phase of the cell cycle. Expression of thyroid-specific genes was evaluated by semi-quantitative RT-PCR measurement of TSH-receptor (TSH-r), Thyroglobulin (Tg) and Thyroid peroxidase (TPO) mRNA levels on cell clones grown at 32oC or 37oC. In the presence of TSH (10mU/ml) an increased expression of all thyroid-specific differentiation markers was observed when cell clones were cultured at 32oC, but not at 37oC, as compared to controls. Our results suggest that restoration of wild type p53 activity is able to partly inhibit ARO cell proliferation by accumulating cells in the G1 phase of the cell cycle. In addition, the reappearance of thyroid-specific gene expression suggests that p53-mediated changes promote cell differentiation. In conclusion, the likelihood of re-inducing follicular differentiation properties may lead to a more efficient approach to thyroid cancer treatment. (The work has been supported by a grant from AIRC).
RESTORATION OF P53 FUNCTION MODULATES PROLIFERATION AND DIFFERENTIATION OF A HUMAN ANAPLASTIC CARCINOMA CELL LINE
1995
Abstract
Alterations of the tumor suppressor gene p53 are detected with high frequency in undifferentiated thyroid carcinomas while are very rare in differentiated thyroid neoplasms. Impairment of p53 function may be responsible for loss of differentiation and acquisition of an aggressive biological behaviour by thyroid tumors. Aim of the study was to evaluate the effects of restoration of wild type p53 activity on cell growth and differentiation of an anaplastic thyroid carcinoma cell line (ARO), characterized by the presence of a mutated p53. ARO cell clones were generated by stable transfection with a temperature-sensitive mutant p53 which exhibited wild type-like properties at 32oC, but was inactive at 37oC. When grown at 32oC, cell clones expressing exogenous p53, as assessed by indirect immunofluorescence, showed a significant reduction of cell proliferation rate (?40%), as compared to controls transfected with vector alone. Inhibition of cell growth was characterized by an increase of cells accumulating in the G1 phase of the cell cycle. Expression of thyroid-specific genes was evaluated by semi-quantitative RT-PCR measurement of TSH-receptor (TSH-r), Thyroglobulin (Tg) and Thyroid peroxidase (TPO) mRNA levels on cell clones grown at 32oC or 37oC. In the presence of TSH (10mU/ml) an increased expression of all thyroid-specific differentiation markers was observed when cell clones were cultured at 32oC, but not at 37oC, as compared to controls. Our results suggest that restoration of wild type p53 activity is able to partly inhibit ARO cell proliferation by accumulating cells in the G1 phase of the cell cycle. In addition, the reappearance of thyroid-specific gene expression suggests that p53-mediated changes promote cell differentiation. In conclusion, the likelihood of re-inducing follicular differentiation properties may lead to a more efficient approach to thyroid cancer treatment. (The work has been supported by a grant from AIRC).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
