ABSTRACT
Objective:To investigate the effect and mechanism of RNaseH-1 on the radiosensitivity of the osteosarcoma cells via the alternative lengthening of telomeres (ALT) mechanism to maintain the telomere length.Methods:ALT osteosarcoma cell U2OS and telomerase-positive osteosarcoma cell 143B over-expressing RNaseH-1 were constructed by lentiviral transfection. After cell transfection, cell proliferation and cell cycle were determined using CCK-8 assay and flow cytometry. The effect of RNaseH-1 on the radiosensitivity of osteosarcoma cells was examined by colony formation assay. DNA injury (γ-H 2AX foci) was assessed by immunofluorescent assay. The expression levels of related proteins were detected by Western blot. Results:The proliferation abilities of U2OS cells were significantly declined following the over-expression of RNaseH-1, and G 1 cell cycle arrest was noted (all P<0.05). Over-expression of RNaseH-1 in U2OS cells increased the phosphorylated levels of ATM and Chk 2, down-regulated the expression of homologous recombination (HR)-related proteins RAD51 and BRCA1significantly aggravated DNA damage and remarkably enhanced the radiosensitivity (all P<0.05). Over-expression of RNaseH-1 exerted no inhibitory effect upon the telomerase-positive 143B cells ( P>0.05). Conclusion:RNaseH-1 over-expression suppresses telomerase-negative osteosarcoma cells and enhances the radiosensitivity probably via the role of RNaseH-1 in inhibiting the homologous recombination repair and activating the ATM signaling pathway.
ABSTRACT
Las enfermedades complejas se caracterizan porque presentan varios genes además de factores ambientales implicados en su etiología. Las bases genéticas de la diabetes mellitus tipo 1 (T1D) supone un efecto mayor del complejo HLA que interactúa con otros genes y con el ambiente. Mucho se ha descrito acerca de la posible participación de las infecciones virales como desencadenadores de T1D. En esta revisión exploramos los posibles mecanismos por los cuales el gen RNASEH1 podría estar participando en la etiología de T1D, a partir de una infección viral. El gen RNASEH1 se localiza en la región cromosómica 2p25, la cual ha sido recientemente implicada por nosotros en la susceptibilidad a T1D. Este gen ha sido implicado en la enfermedad mediante análisis genético. Acá pretendemos dar sentido biológico a los datos genéticos. Considerando que la enfermedad es multifactorial, este planteamiento no excluye la participación de otros genes u otros factores ambientales.
Complex disorders are characterized by presenting many genes and other environmental factors implicated in their etiology. The genetic bases of type 1 diabetes mellitus (T1D) suppose a major effect of the HLA complex which interacts with other genes and the environment. Much has been written about the possible implication of viral infections as triggers of T1D. This review explores the mechanisms by which the RNASEH1 gene could be involved in the etiology of T1D, due to a viral infection. The RNASEH1 gene is located in chromosome 2p25, which has been recently implicated in the susceptibility to T1D by the authors, through genetic analysis.This text hopes to establish a biological context for the genetic data. Taking into account that this is a multifactorial disease, this approach does not exclude the eventual participation of other genes or environmental factors.