| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 98 === Cervical cancer is the second most common cancer among women worldwide. Although high risk human papillomavirus (HPV) is the major factor for cervical cancer, other factors such as E2, a major estrogen, are thought to play roles in the formation of cervical cancer. E2 has two types of estrogen receptors (ERα and ERβ), and most estrogen-related studies are in breast cancer. It was known that activated ERα increases cell proliferation through both genomic and non-genomic pathways; activated ERβ decreases cell proliferation and increases apoptosis by modulating ERα activity, mainly through non-genomic pathways in breast cancer cells. The ERα is also required for proliferation in cervical cancer. However, there are fewer reports explore the role of ERβ in cell proliferation in cervical cancer cells. The purpose of this study was to discover the non-genomic mechanism by which activated ERβ modulated cell proliferation in HeLa cells, a cervical cancer cell line. First of all, the expression of ERα and ERβ in mammary gland cells (4T1 and MCF7), lung cells (A549 and L2) and a cervical cancer cell (HeLa) was detected. When compared with MCF7 which expressed ERα and ERβ, A549, L2, HeLa and 4T1 expressed ERβ only. MTT assay showed that E2 at 1 μM increased the viability of MCF7, and decreased viability of HeLa. E2 at 1 μM increased cell number in conjunction with the decrease cells at G0/G1 and increased cells at S in MCF7 but that decreased cell number in conjunction with the increased cells at Sub G0 and the decreased cells at S in HeLa. Overexpression of ERβ?increased the cells at Sub G0 and decreased the cells at S and G2/M in MCF7 but that did not affect the cells at Sub G0 and decreased the cells at S and G2/M in HeLa. Immunoprecipitation coupled with differential proteomic analysis showed E2 (at 1 μM)-mediated decreases in the abundance ratio of proteins associated with ERβ, including histone H4, thyroid hormone receptor-associated protein, and heat shock protein 90 (Hsp90), and increased the abundance of histone H2B and H1.2 in the nuclei. However, E2 at 10 nM decreased the histone H2B and increased proliferation associated-protein 2G4 in the nuclei. All our findings suggest that the binding of E2 at 1 μM to ERβ causes the dissociation of histone H4 and Hsp90 from the ERβ complex, which may contribute to the deceleration of cell cycle progression to S and G2/M phases and decrease cell number in HeLa cells. And E2 at 10 nM did not affect cell cycle progression in HeLa cells.
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