benzyloxycarbonylleucyl-leucyl-leucine-aldehyde and Uterine-Neoplasms

Embryo implantation involves invasion of placental extravillous trophoblast cell (EVTs) into the uterus. Hyperactive EVT invasion occurs in hydatidiform moles and choriocarcinomas. We have previously demonstrated that the 20S proteasome is involved in mouse embryo implantation and its action is mediated via regulating the expression and activities of matrix metalloproteinase (MMP)-2 and MMP-9 in the EVTs. Our objective was to investigate whether low molecular mass polypeptide-2 (LMP2), a beta subunit of the 20S proteasome, is involved in the regulation of human trophoblast invasion. Normal human placentas or placentas from hydatidiform mole patients were collected and the expression of LMP2 in different cell types including trophoblastic column (TC), cytotrophoblast cells (CTB) and syncytiotrophoblast (STB) under different pathological states were studied by immunohistochemical analysis. Furthermore, the effect of LMP2 or proteasome on cell invasion was measured by using RNAi and inhibitors in a Matrigel invasion assay system in HTR-8/SVneo cells, a human invasive extravillous trophoblast cell line. Changes in the invasion-related molecules including MMP-2 and MMP-9 were also examined by using real time PCR and gelatin zymography. We demonstrated that the expression of LMP2 in TC of partial hydatidiform mole and complete hydatidiform mole, is higher than that in TC of normal human placentas. Besides, LMP2 knockdown significantly attenuated IL-1beta-induced cell invasion in vitro, a response readily induced by proteasome inhibitors. In summary, over-expression of the 20S proteasome beta-subunit LMP2 in trophoblast cells of hydatidiform moles may contribute to its highly invasive phenotype.

Topics: Acetylcysteine; Cell Line; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Embryo Implantation; Female; Humans; Hydatidiform Mole; Immunohistochemistry; In Vitro Techniques; Interleukin-1beta; Leupeptins; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Placentation; Pregnancy; RNA Interference; Trophoblasts; Uterine Neoplasms

Estrogen receptor alpha (ERalpha)-positive breast cancer cell lines are up to 10 times more sensitive than ERalpha-negative cell lines to the antiproliferative activity of the histone deacetylase inhibitor trichostatin A (TSA). The purpose of the study was to investigate the mechanisms underlying this differential response.. In the ERalpha-positive MCF-7 cell line, TSA repressed ERalpha and cyclin D1 transcription and induced ubiquitin dependent proteasomal degradation of cyclin D1, leading primarily to G(1)-S-phase cell cycle arrest. By contrast, cyclin D1 degradation was enhanced but its transcription unaffected by TSA in the ERalpha-negative MDA-MB-231 cell line, which arrested in G(2)-M phase. Cyclin D1 degradation involved Skp2/p45, a regulatory component of the Skp1/Cullin/F-box complex; silencing SKP2 gene expression by RNA interference stabilized cyclin D1 and abrogated the cyclin D1 down-regulation response to TSA.. Tamoxifen has been shown to inhibit ERalpha-mediated cyclin D1 transcription, and acquired resistance to tamoxifen is associated with a shift to ERalpha-independent cyclin D1 up-regulation. Taken together, our data show that TSA effectively induces cyclin D1 down-regulation through both ERalpha-dependent and ERalpha-independent mechanisms, providing an important new strategy for combating resistance to antiestrogens.

Topics: Antineoplastic Agents, Hormonal; Breast Neoplasms; Cell Cycle; Cell Proliferation; Cyclin D1; Cysteine Proteinase Inhibitors; Drug Resistance, Neoplasm; Endopeptidases; Estrogen Receptor alpha; Female; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Leupeptins; RNA Interference; S-Phase Kinase-Associated Proteins; Tamoxifen; Transcription, Genetic; Tumor Cells, Cultured; Uterine Neoplasms