Immunohistochemical and mutational analysis of p53 tumor suppressor gene in gestational trophoblastic disease: correlation with mdm2, proliferation index, and clinicopathologic parameters

Abstract

The role of p53 in the pathogenesis of gestational trophoblastic disease (GTD) was investigated. Immunohistochemical studies for p53, its regulator mdm2, and proliferation marker Ki67 were performed on paraffin-embedded tissues of 28 partial moles (PM), 57 complete moles (CM), 14 choriocarcinomas (CCA), and 31 normal placentas. Three antibodies to p53 (DO-7, Ab-2, Ab-3) were used and demonstrated immunoreactivity for wild-type p53 protein predominantly in the nuclei of cytotrophoblasts. Direct DNA sequencing of 36 hydatidiform moles using frozen tissues confirmed an absence of mutational changes in exons 5-8. CCA was found to have the highest p53 protein expression, followed by CM, PM, and normal placenta (P < 0.001). In normal placentas (P = 0.0001), PM, and CM (P = 0.016), an inverse correlation between their gestational age and p53 expression was observed. p53 expression was found to correlate with proliferation index in normal placenta (P = 0.0001) and all three groups of GTD (P = 0.012). Significant correlation between p53 and mdm2 expression was also observed (P < 0.01). The distinctive expression of p53 wild-type protein in the cytotrophoblasts and its positive correlation with the proliferative index suggests that its overexpression in GTD may be related to its effect on cell proliferation. The parallel expression of mdm2 and p53 also supports the presence of an autoregulatory feedback loop in the control of this process. No correlation could be found between clinical progress of the patients with hydatidiform moles, and the p53 (P = 0.78) or mdm2 protein (P = 0.54) expression suggesting that neither of them carries any prognostic significance.

Intra-uterine growth restriction is associated with increased apoptosis and altered expression of proteins in the p53 pathway in villous trophoblast

“…The downstream responses to exaggerated p53 expression, particularly increased p21 expression, are similar to those described following placental explant culture in 1% O 2 [36]. The absence of an alteration in Mdm2 was surprising as it is a primary transcriptional target of p53 [37], and is correlated with placental p53 expression in molar pregnancy and choriocarcinoma [38]. In our previous studies using trophoblast, the response of Mdm2 to increased p53 in trophoblast is less clear than other cell types.…”

Downregulation of ASPP1 in gestational trophoblastic disease: correlation with hypermethylation, apoptotic activity and clinical outcome

“…17,18 Data on proliferation and apoptosis indices of these cases were also retrieved from previous studies to be correlated with ASPP1 immunoreactivity. 3,6,[19][20][21] For in vitro studies, two choriocarcinoma cell lines (JEG-3 and JAR) (American Type Culture Collection, Manassas, VA, USA) were cultured in minimum essential Eagle's medium supplemented with 10% fetal bovine serum and 100 Units/ml penicillin and streptomycin.…”

“…Overexpression of wild-type p53 [6][7][8]20,21 and higher apoptotic activities 3,4,9,36 have been reported in hydatidiform moles and choriocarcinomas than in normal or hydropic placentas. It has been suggested that overexpression of wild-type p53 accompanying increased apoptotic activity would be a protective mechanism to counterbalance the uncontrolled proliferation in gestational trophoblastic disease.…”

Caspase activity is downregulated in choriocarcinoma: a cDNA array differential expression study

“…1 In our previous studies, we demonstrated the differential expression of individual oncogenes in GTD, [2][3][4][5] and showed that telomerase activity and apoptosis are probably related to the clinical outcome of HM. 2 6 7 Recently, we used apoptotic cDNA arrays, and identified Mcl-1, an apoptosis related gene, as being related to the clinical progression of HM.…”