Gene expression profile in human trophoblast and gestational trophoblastic disease
Abstract of thesis entitled
GENE EXPRESSION PROFILE IN HUMAN TROPHOBLAST AND GESTATIONAL TROPHOBLASTIC DISEASE
for the degree of Doctor of Philosophy
at the University of Hong Kong
in August 2004
Trophoblast in normal placenta is pseudo-malignant in nature. Neoplastic transformation of trophoblast leads to gestational trophoblastic diseases (GTD). Choriocarcinoma (CCA) and hydatidiform mole (HM) are major types of GTD. Generally GTD shows varying potential for local invasion and metastasis, but responds well to chemotherapy. The major problem in the treatment of GTD is the delay of chemotherapy particularly in highly malignant cases. Identification of predictive molecular markers may improve the early diagnosis for malignant GTD.
In this study, both trophoblastic cell lines and clinical tissues were used in the examination of differentially expressed genes using various approaches. Their gene expression profiles were used in the identification of potential molecular markers for GTD.
Twenty-three differentially expressed genes in CCA were identified from the comparison of gene expression profiles between two CCA cell lines (JAR and JEG-3) and a non-malignant villous trophoblastic cell line (B6hTERT), using the Atlas?Human Cancer 1.2 array. The B6hTERT is a newly established trophoblastic cell line immortalized with the
hTERT (human telomerase reverse transcriptase) gene. Down-regulation of TIMP3 was confirmed by immunohistochemistry in clinical specimens of CCA. Promoter methylation of TIMP3 was also observed in GTD, which may be involved in its down-regulation. This study indicated that down-regulation of TIMP3 in CCA may play a role in its pathogenesis, and may have potential application in clinical diagnosis and patient treatment in GTD.
The genes regulated by TGF? (a common cytokine at the implantation site) in invasive extravillous trophoblast were examined in a non-malignant extravillous trophoblastic cell line (PE1-7) using the Stanford microarray. The PE1-7 was immortalized by HPV16 E6/E7 and characterized in this study. Up-regulation of IGFBP3 by TGF? was identified, which may be involved in the regulation of proliferation and invasion of extravillous trophoblast. The examination of gene expression profile regulated by TGF? may provide new insights into its roles in extravillous trophoblast.
Both ?andidate gene approach?and ?lobal gene discovery?were used to identify the differentially expressed genes in normal placenta, regressive mole and persistent mole. The candidate gene examined was the cadherin family expressed in normal placenta and HM using degenerated PCR. The major cadherins expressed in normal placenta and HM are E-cadherin and cadherin 11 (both wild type and variant form). Down-regulation of E-cadherin and up-regulation of cadherin 11 were observed in HM. Cadherin 6 was observed to express at low level in normal placenta and HM. Up-regulation of cadherin 6 was also observed in HM. No distinct difference in cadherin expression pattern was observed between regressive and persistent moles. The ?lobal gene discovery?was performed by cDNA microarray with self-made chips [constructed from SSH (Suppression Subtraction Hybridization) subtracted tissues-specific libraries] and pre-made chips (from Stanford
Functional Genomics Facility). Down-regulation of IGFBP1 and up-regulation of PSCA were observed in persistent mole were confirmed at both mRNA and protein levels. Comparison of global gene expression profiles between normal placenta and HM, and between regressive and persistent mole have provided new insights into the molecular events regulating behaviors of normal and abnormal trophoblasts.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:trophoblast trophoblastic tumors genetic aspects gene expression
Date of Publication:01/01/2005