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We used a PCR-based subtraction method, representational difference analysis of cDNA (cDNA--RDA), to identify genes with a higher expression in leiomyomas in comparison with the corresponding myometrium during the proliferative phase of the menstrual cycle. Increased expression of the genes for pregnancy-associated plasma protein A (PAPPA), tomoregulin, cellular retinoid acid binding protein 1 (CRABP1), zinc finger protein 185 (ZFP 185) and latent transforming growth factor beta binding protein 2 (LTBP2) was demonstrated in individual leiomyoma samples compared with corresponding myometrium. Additionally, a specific positive immunostaining of LTBP2 was found in the smooth muscle cells of both leiomyomas and myometrium. These genes may be part of previously unidentified molecular mechanisms responsible for the selective growth advantage of leiomyomas compared with myometrium. This work expands our knowledge about the molecular nature of leiomyomas and provides novel candidate genes to further explore in relation to their function during leiomyoma growth.

Choriocarcinoma is a highly malignant tumor that can arise from trophoblasts of any type of gestational event but most often from complete hydatidiform mole. IGF-II plays a fundamental role in placental development and may play a role in gestational trophoblastic diseases. Several studies have shown that IGF-II is expressed at high levels in hydatidiform moles and choriocarcinoma tissues; however, conflicting data exist on how IGF-II regulates the behaviour of choriocarcinoma cells. The purpose of this study was to determine the contribution of the receptors for IGF-I and insulin to the actions of IGF-II on the regulation of choriocarcinoma cells metastasis. An Immuno Radio Metric Assay was used to analyse the circulating and tissue levels of IGF-I and IGF-II in 24 cases of hydatidiform mole, two cases of choriocarcinoma and eight cases of spontaneous abortion at the same gestational age. The JEG-3 choriocarcinoma cell line was used to investigate the role of IGF-II in the regulation of cell invasion. We found that mole and choriocarcinoma tissue express high levels of IGF-II compared to first trimester placenta. Both IGF-I and IGF-II regulate choriocarcinoma cell invasion in a dose dependent manner but through a different mechanism. IGF-II effects involve the activation of the InsR while IGF-I uses the IGF-IR. The positive effects of IGF-II on invasion are the result of enhanced cell adhesion and chemotaxis (specifically towards collagen IV). The actions of IGF-II but not those of IGF-I were sensitive to inhibition by the insulin receptor inhibitor HNMPA(AM)3. Our results demonstrate that the insulin receptor regulates choriocarcinoma cell invasion.