Partial knockdown of TRF2 increase radiosensitivity of human mesenchymal stem cells

Telomere repeat binding factor TRF2 is a member of shelterin complex with an important role in protecting and stabilizing chromosomal ends. In the present study, we investigated the effect of partial knockdown of TRF2 on radiosensitivity of telomerase immortalized human mesenchymal stem cells (hMSC-telo1), which have a higher radioresistance compared to non telomerized counterpart. Partial knockdown of the protein achieved 15-20% reduction in TRF2 protein levels. The study compared the effect of 2.5 Gy radiation in two four days after irradiation for hMSC-telol cells and the cells transfected with siTRF2 and null control vector. Radio-response of the cells were examined using senescence associated beta-Gal assay (beta-Gal), colony forming assay (CFU) and gamma-H2AX phosphorylation. TRF2 deficiency substantially increased radiosensitivity of cells compared to controls in both proliferation and senescence assay (2.4 fold increase in beta-Gal, 1.6 fold decrease in CFU). In addition, it increased the gamma-H2AX foci as revealed by both immunfluorescence and Western blot analysis. Our data suggests that partial knockdown of TRF2 in hMSC-telol cells cause increased gamma-H2AX foci which led to fail TRF2 to protect telomeres from radiation thus TRF2 deficiency led to a 1,5-2 fold increase in the radiosensitivity of hMSC-telol cells through telomere destabilization. (C) 2015 Elsevier B.V. All rights reserved

Biological effects of whole Z.Officinale extract on chronic myeloid leukemia cell line K562

© 2019The anticancer activity of Zingiber officinalis (ginger) is an area of active research. However, data is quite limited regarding its action and mechanism, especially in hematologic cancer types. Here, antiproliferative and apoptotic effects of whole extract of the rhizome of Zingiber officinalis (ZOWE), was investigated in K562 cell line derived from a chronic myeloid leukemia (CML) patient. Various concentrations of whole extract (0, 10, 25, 50 and 100 μM) were tested in K562 cultures. Cytotoxicity and apoptosis was assessed with appropriate methods, as well as cellular ROS levels. In this study, we showed that ZOWE inhibited proliferation of K562 cells substantially, when compared to peripheral blood mononuclear cells (PBMCs) isolated from healthy donor. Increased Bax/Bcl-2 ratio, reduced mitochondrial membrane potential and increased PARP cleavage demonstrated that ZOWE inhibited proliferation by induction of apoptosis. These changes were coupled with an increase of reactive oxygen species (ROS) production. Furthermore, ZOWE addition to the culture also reduced expression levels of survival proteins pAkt and survivin, in a concentration dependent manner. Our results clearly mark that ZOWE causes to a reduction in cell viability, an induction of apoptosis and elevation in ROS levels in chronic myeloid leukemia cells and effects are significantly different from healthy peripheral blood mononuclear cells, further supporting its potential therapeutic value