Alterations of tumor suppressor gene p53 are detected at high frequency in undifferentiated thyroid carcinomas but are very rare in differentiated thyroid neoplasms. Impairment of p53 function in thyroid tumors may be responsible for loss of differentiation and acquisition of aggressive biological behavior. Effects of restoration of wild type p53 activity were evaluated in three human carcinoma cell lines, showing distinct endogenous p53 gene status, derived from thyroid tumors exhibiting different degrees of differentiation and aggressiveness. Wild-type p53 re-expression was obtained by using an inducible construct, resulting from fusion of human p53 coding sequence with the carboxyl-terminus of the estrogen receptor (p53ER), whose activity is induced by 4-hydroxy-tamoxifene. Presence of p53ER in the various thyroid carcinoma cell lines was evaluated by Western blot and indirect immunofluorescence techniques while its transactivation properties were assessed in transient transfection assays with reporter plasmids spanning p53 binding sequences. P53ER expression in WRO cells, derived from a follicular thyroid carcinoma and containing a mutated endogenous p53 allele (L223P), caused a rapid and massive cell death followed by almost complete growth inhibition, probably due to G1 cell accumulation. FRO cells, derived from a poorly differentiated follicular carcinoma and containing a normal p53 gene, were unaffected by p53ER, reinforcing the notion (indicating) that additional p53 activity is not deleterious in a normal p53 cell environment. ARO cells, derived from an anaplastic thyroid carcinoma and showing an emizygous mutant p53 allele (R273H), were strongly inhibited in their growth potential by p53ER which caused G1 cell accumulation. In conclusion, wild type p53 re-expression differentially affects proliferation of human thyroid carcinoma cells depending upon their endogenous p53 gene status. (Experiments supported by an AIRC research grant).
RESTORATION OF WILD TYPE P53 ACTIVITY IN HUMAN THYROID CARCINOMA CELLS DERIVED FROM DIFFERENT TUMOR TYPES
1998
Abstract
Alterations of tumor suppressor gene p53 are detected at high frequency in undifferentiated thyroid carcinomas but are very rare in differentiated thyroid neoplasms. Impairment of p53 function in thyroid tumors may be responsible for loss of differentiation and acquisition of aggressive biological behavior. Effects of restoration of wild type p53 activity were evaluated in three human carcinoma cell lines, showing distinct endogenous p53 gene status, derived from thyroid tumors exhibiting different degrees of differentiation and aggressiveness. Wild-type p53 re-expression was obtained by using an inducible construct, resulting from fusion of human p53 coding sequence with the carboxyl-terminus of the estrogen receptor (p53ER), whose activity is induced by 4-hydroxy-tamoxifene. Presence of p53ER in the various thyroid carcinoma cell lines was evaluated by Western blot and indirect immunofluorescence techniques while its transactivation properties were assessed in transient transfection assays with reporter plasmids spanning p53 binding sequences. P53ER expression in WRO cells, derived from a follicular thyroid carcinoma and containing a mutated endogenous p53 allele (L223P), caused a rapid and massive cell death followed by almost complete growth inhibition, probably due to G1 cell accumulation. FRO cells, derived from a poorly differentiated follicular carcinoma and containing a normal p53 gene, were unaffected by p53ER, reinforcing the notion (indicating) that additional p53 activity is not deleterious in a normal p53 cell environment. ARO cells, derived from an anaplastic thyroid carcinoma and showing an emizygous mutant p53 allele (R273H), were strongly inhibited in their growth potential by p53ER which caused G1 cell accumulation. In conclusion, wild type p53 re-expression differentially affects proliferation of human thyroid carcinoma cells depending upon their endogenous p53 gene status. (Experiments supported by an AIRC research grant).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
