Reprimo as a modulator of cell migration and invasion in the MDA-MB-231 breast cancer cell line

BACKGROUND: Reprimo (RPRM), a highly glycosylated protein, is a new downstream effector of p53-induced cell cycle arrest at the G2/M checkpoint, and a putative tumor suppressor gene frequently silenced via methylation of its promoter region in several malignances. The aim of this study was to characterize the epigenetic inactivation and its biological function in BC cell lines. METHODS: The correlation between RPRM methylation and loss of mRNA expression was assessed in six breast cancer cell lines by methylation specific PCR (MSP), 5'-Aza-2'-deoxycytidine treatment and RT-PCR assays. MDA-MB-231 cells were chosen to investigate the phenotypic effect of RPRM in cell proliferation, cell cycle, cell death, cell migration and invasion. RESULTS: In the cancer methylome system (CMS) (web-based system for visualizing and analyzing genome-wide methylation data of human cancers), the CpG island region of RPRM (1.1 kb) was hypermethylated in breast cancer compared to normal breast tissue; more interesting still was that ERa(+) tumors showed higher methylation intensity than ERa(-). Downregulation of RPRM mRNA by methylation was confirmed in MDA-MB-231 and BT-20 cell lines. In addition, overexpression of RPRM in MDA-MB-231 cells resulted in decreased rates of cell migration, wound healing and invasion in vitro. However, RPRM overexpression did not alter cell viability, phosphatidylserine (PS) translocation or G2/M cell cycle transition. CONCLUSION: Taken together, these data suggest that RPRM is involved in decreased cell migration and invasion in vitro, acting as a potential tumor suppressor gene in the MDA-MB-231 cell line.

Low dose hyper-radiosensitivity in human lung cancer cell line A549 and its possible mechanisms / 华中科技大学学报（医学）（英德文版）

The low dose hyper-radiosensitivity (HRS) in human lung cancer cell line A549 was investigated, the changes of ATM kinase, cell cycle and apoptosis of cells at different doses of radiation were observed, and the possible mechanisms were discussed. A549 cells in logarithmic growth phase were irradiated with (60)Co gamma-rays at doses of 0-2 Gy. Together with flow cytometry for precise cell sorting, cell survival fraction was measured by means of conventional colony-formation assay. The expression of ATM1981Ser-P protein was examined by Western blot 1 h after radiation. Apoptosis was detected by Hoechst 33258 fluorescent staining, and Annexin V-FITC/PI staining flow cytometry 24 h after radiation. Cell cycle distribution was observed by flow cytometry 6, 12 and 24 h after radiation. The results showed that the expression of ATM1981Ser-P protein was observed at 0.2 Gy, followed by an increase at >0.2 Gy, and reached the peak at 0.5 Gy, with little further increase as the dose exceeded 0.5 Gy. Twenty-four h after radiation, partial cells presented the characteristic morphological changes of apoptosis, and the cell apoptosis curve was coincident with the survival curve. As compared with control group, the cell cycle almost had no changes after exposure to 0.1 and 0.2 Gy radiation (P>0.05). After exposure to 0.3, 0.4 and 0.5 Gy radiation, G(2)/M phase arrest occurred 6 and 12 h after radiation (P<0.05), and the ratio of G(2)/M phase cells was decreased 24 h after radiation (P<0.05). It was concluded that A549 cells displayed the phenomenon of HRS/IRR. The mode of cell death was mainly apoptosis. The activity of ATM and cell cycle change may take an important role in HRS/IRR.

El ciclo celular y su papel en la biología de las células progenitoras hematopoyéticas / The cell cycle and its role in the biology of haematopoietic progenitor cells

El ciclo celular constituye el conjunto de eventos que determinan la actividad metabólica de toda célula así como su división y la generación de células hijas. Este proceso está involucrado en todos los procesos celulares tales como proliferación y diferenciación. Se ha demostrado que diversos elementos moleculares participan en su regulación y que alteraciones en este proceso pueden conducir a trastornos fisiológicos e incluso a la muerte del organismo. En los mamíferos, uno de los tejidos con mayor recambio celular es el hematopoyético, por lo que se requiere un control muy estricto del ciclo celular, principalmente a nivel de células troncales y progenitoras para la óptima producción de células sanguíneas. En este artículo presentamos un panorama general de los principales mecanismos y factores involucrados en la regulación del ciclo celular, poniendo particular énfasis en su papel en la biología de las células hematopoyéticas primitivas.

The cell cycle comprises a group of biological events that determine the metabolic activity of any cell, as well as its division and the generation of new daughter cells. It is involved in every cellular process, such asproliferation and differentiation. It has been shown that several molecular elements regulate the cell cycle, and that alterations in any of its phases and/or regulators could give rise to physiologic deficiencies, and even death. In mammals, the haematopoietic tissue is one of the most active in terms of cell replacement; thus, a tight cell cycle control, particularly at the level of stem and progenitors cells is crucial for optimal blood cell production. In the present article, we give a comprehensive overview of the major mechanisms and regulatory, molecules that participate in the cell cycle of mammalian cells, with particular emphasis on its role in the biology of primitive cells of the hematopoietic system.

Marcadores biológicos de tumores tiroidianos / Biological markers in thyroid tumors

Um marcador biológico ideal deve ser específico e sensível para identificar o tipo tumoral e caracterizar o estágio da progressão neoplásica. Os tumores de tiróide originam-se de dois tipos celulares: 1) carcinoma medular originário de células parafoliculares; e 2) as neoplasias de células epiteliais foliculares, que incluem bócio, adenomas, carcinomas diferenciados (carcinoma papilífero e carcinoma folicular) e carcinoma indiferenciado (carcinoma anaplásico). O comportamento biológico distinto faz com que cada tipo tumoral necessite de uma conduta terapêutica específica. O conhecimento acumulado ao longo destes anos, utilizando métodos de biologia molecular e, mais recentemente, a genômica, identificou mutações específicas de câncer de tiróide e, atualmente, entendemos muito das alterações que ocorrem na expressão de fatores de crescimento, seus receptores e proteínas sinalizadoras intracelular nas neoplasias tiroidianas. Contudo, apesar desses, até o momento não dispomos de um marcador eficiente que auxilie no diagnóstico e prognóstico e, conseqüentemente, para indicação de uma terapêutica mais adequada. Nesta revisão, discutiremos os principais aspectos relacionados à tumorigênese tiroidiana, avaliando o potencial destes fatores como marcador em neoplasia folicular de tiróide.