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

Abstract

Gestational trophoblastic disease encompasses a spectrum of trophoblastic lesions including true neoplasms such as choriocarcinomas and the potentially malignant hydatidiform moles, which may develop persistent disease requiring chemotherapy. ASPP1, a member of apoptosis-stimulating proteins of p53 (ASPPs), is a proapoptotic protein that can stimulate apoptosis through its interaction with p53. We evaluated the promoter methylation and expression profiles of ASPP1 in different trophoblastic tissues and its in vitro functional effect on two choriocarcinoma cell lines, namely JEG-3 and JAR. Significant downregulation of ASPP1 mRNA and protein levels was demonstrated in hydatidiform moles and choriocarcinomas, when compared with normal placentas by quantitative-PCR and immunohistochemistry. The ASPP1 mRNA level was significantly correlated with its hypermethylation status, evaluated with methylation-specific PCR, in placenta and gestational trophoblastic disease samples (P ¼ 0.024). Moreover, lower ASPP1 immunoreactivity was shown in hydatidiform moles that progressed to persistent gestational trophoblastic neoplasms than in those that regressed (P ¼ 0.045). A significant correlation was also found between expression of ASPP1 and proliferative indices (assessed by Ki67 and MCM7), apoptotic activity (M30 CytoDeath antibody), p53 and caspase-8 immunoreactivities. An in vitro study showed that ectopic expression of ASPP1 could trigger apoptosis through intrinsic and extrinsic pathways as indicated by an increase in cleaved caspase-9 and Fas ligand protein expression. The latter suggests a hitherto unreported novel link between ASPP1 and the extrinsic pathway of apoptosis. Our findings suggest that downregulation of ASPP1 by hypermethylation may be involved in the pathogenesis and progress of gestational trophoblastic disease, probably through its effect on apoptosis.

MicroRNA-34a is a tumor suppressor in choriocarcinoma via regulation of Delta-like1

“…Suppression of the apoptosis-stimulating proteins of p53 (ASPP1), a member of the p53 transcriptional complex, through promoter hypermethylation in choriocarcinoma cell lines supports this possibility [27]. In fact, force-expression of ASPP1 in choriocarcinoma cell line has profound effects on reducing tumorigenecity [27]. The present study suggests that miR-34a is another component of the p53 network important in tumor suppression.…”

“…It is possible that there is a malfunction of the p53 effectors in the choriocarcinoma enabling the cells to survive under such condition. Suppression of the apoptosis-stimulating proteins of p53 (ASPP1), a member of the p53 transcriptional complex, through promoter hypermethylation in choriocarcinoma cell lines supports this possibility [27]. In fact, force-expression of ASPP1 in choriocarcinoma cell line has profound effects on reducing tumorigenecity [27].…”

FBI-1 Is Overexpressed in Gestational Trophoblastic Disease and Promotes Tumor Growth and Cell Aggressiveness of Choriocarcinoma via PI3K/Akt Signaling

“…15 In GTD, p53-related genes or regulators play crucial roles in modulating apoptosis during disease progression. 9,11 Also, the involvement of these regulators in crosstalk between apoptosis and the cell signaling pathway in GTD may result in an adverse clinical outcome. For example, we have previously demonstrated that proapoptotic apoptosisstimulating protein of p53 2 is down-regulated in highly metastatic CCA and contributes to increased migratory potential through the activation of the Src signaling pathway.…”

“…9 Surprisingly, on qPCR analysis, subsequent down-regulation of a broad range of proapoptotic genes involved in the extrinsic and intrinsic pathways of apoptosis at the transcript level, such as FAS, CASP8, CASp10, BAK, CASP9, as well as polyeADP ribose polymerases, was demonstrated in FBI1etransfected JAR and JEG-3 ( Figure 5), demonstrating a potent antiapoptotic nature of FBI-1 in apoptosis regulation.…”

Assessment of Apoptotic Activity Dysregulation and Oxidative Stress in the Development of Epithelial Ovarian Cancer: A Case-Controlled Descriptive Analysis

“…There are two pathways for the occurrence of apoptosis: extrinsic and intrinsic pathways. Extrinsic pathways are regulated by members of the tumour necrosis factor family; intrinsic pathways are induced by cellular stress, such as discontinuation of growth factor support, unfolded protein response, DNA damage and ROS [25,26]. M30/M65 antibodies that enable the demonstration of caspase-cleaved activation products of CK-18 in the circulation can be used to determine apoptosis in addition to morphological evaluation of tissue samples using electron and light microscopy technology [26,27].…”