The present study evaluated the protective effect of the natural compound flavonoids of Rosa roxburghii Tratt (FRT) against γ-radiation-induced apoptosis and inflammation in mouse thymus cells in vivo and in vitro. Thymus cells and mice were exposed to Co γ-ray at a dose of 6 Gy. The radiation treatment induced significant cell apoptosis and inflammation. Radiation increased the expressions of cleaved caspase 3/8-10, AIF, and PARP-1, and FRT could mitigate their activation and inhibit subsequent apoptosis in the thymus both in vitro or in vivo. Irradiation increased the mRNA expression of ICAM-1/VCAM-1, IL-1α/IL-6 and TNF-α/NF-κB. Our results also indicated that FRT alleviated gene expression of some inflammatory factors such as ICAM-1/VCAM-1, TNF-α/NF-κB, but not IL-1α/IL-6. Irradiation increased the protein expression levels of ICAM-1/VCAM-1, IL-1α/IL-6 and TNF-α/NF-Κb, and our results also indicated that FRT alleviated protein level expression of certain inflammatory factors such as ICAM-1, IL-1α/IL-6, TNF-α/NF-κB, but not VCAM-1. Our results suggested that FRT enhanced radioprotection at least partially by regulating caspase 3/8-10, AIF, and PARP-1 to reduce apoptosis and by regulating ICAM-1, IL-1α/IL-6, TNF-α/NF-κB to reduce inflammation.
Radiotherapy is one of the most effective non-surgical treatments for many tumors. However, radiation damage remains a major negative consequence of radiotherapy. At present, radio-protective effect of troxerutin has been confirmed, but the mechanism of this radioprotection has not been elucidated. Here, this study showed that troxerutin protected thymus tissue of irradiated mice, and its radio-protective effect on thymocytes was significant in the range of 0.625-10μg/ml. Troxerutin significantly inhibited apoptosis of irradiated thymocytes at the concentration of 10μg/ml. Computer-aided drug design was used to investigate potential candidate targets for troxerutin, and an excellent correlation was identified between troxerutin and AKT (Pharm mapper and KEGG signal pathway). Troxerutin inhibited the activation of PTEN to stimulate AKT, which in turn prevented the activation of JNK to protect cells. Our results showed that troxerutin enhanced radioprotection at least partially by activating AKT to inhibit the activation of JNK.
p15INK4B, a cyclin-dependent kinase inhibitor, has been recognized as a tumor
suppressor. Loss of or methylation of the p15INK4B gene in chronic
myeloid leukemia (CML) cells enhances myeloid progenitor formation from common
myeloid progenitors. Therefore, we examined the effects of overexpressed p15INK4B on
proliferation and apoptosis of CML cells. Overexpression of p15INK4B inhibited the
growth of K562 cells by downregulation of cyclin-dependent kinase 4 (CDK4) and cyclin
D1 expression. Overexpression of p15INK4B also induced apoptosis of K562 cells by
upregulating Bax expression and downregulating Bcl-2 expression. Overexpression of
p15INK4B together with STI571 (imatinib) or BCR-ABL1 small interfering RNA (siRNA)
also enhanced growth inhibition and apoptosis induction of K562 cells. The enhanced
effect was also mediated by reduction of cyclin D1 and CDK4 and regulation of Bax and
Bcl-2. In conclusion, our study may provide new insights into the role of p15INK4B in
CML and a potential therapeutic target for overcoming tyrosine kinase inhibitor
resistance in CML.
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