Stress-induced senescence of tumor cells by chemotherapy, good or bad? / 中国药理学通报

Traditionally it is believed that stress-induced senescence of tumor cells induced by chemotherapy is beneficial to inhibit tumor growth and progression, and has a positive effect on anti-tumor. However, with the longtime observation and clinical study on the anti-tumor effect of chemotherapy in the real world, it is found that tumor cells often show stronger proliferation and invasiveness after chemotherapy or relapse, tumor recurrence and refractoriness become very hot and tricky issues. So, it is necessary to rethink and explore the real process and potential effect of stress-induced senescence by chemotherapy. Here from the perspective of stress-induced senescence of tumor cells by chemotherapy, this study mainly analyzes and discusses the potential negative effects and clinical significance, so as to fully understand its pros and cons in the anti-tumor effect, hoping to provide some new ideas and rationale for improving traditional tumor chemotherapy, developing new anti-tumor drugs and coming out of the current dilemma of chemotherapy.

Rat Notochordal Cells Undergo Premature Stress-Induced Senescence by High Glucose

STUDY DESIGN: In vitro cell culture. PURPOSE: The purpose of the study was to investigate the effect of high glucose on premature stress-induced senescence of rat notochordal cells. OVERVIEW OF LITERATURE: Glucose-mediated increase of oxidative stress is a major causative factor for the development of diseases associated with diabetes mellitus such as senescence. However, no information is available for the effect of high glucose on premature stress-induced senescence of rat notochordal cells. METHODS: Notochordal cells were isolated from 4-week-old rats, cultured and placed in either 10% fetal bovine serum (FBS, normal control) or 10% FBS plus two high glucose concentrations (0.1 M and 0.2 M, experimental conditions) for 1 and 3 days. We identified and quantified the mitochondrial damage (mitochondrial transmembrane potential), reactive oxygen species (ROS) and antioxidants, such as manganese superoxide dismutase (MnSOD) and catalase, for each condition. We also identified and quantified senescence and telomerase activity. Finally, we determined the expression of proteins related to replicative senescence (p53-p21-pRB) and stress-induced senescence (p16-pRB) pathways. RESULTS: Two high glucose concentrations enhanced the disruption of mitochondrial transmembrane potential and excessive generation of ROS in notochordal cells for 1 and 3 days, respectively. The expressions of MnSOD and catalase were increased in notochordal cells treated with both high glucose concentrations at 1 and 3 days. The telomerase activity declined at 1 and 3 days. Two high glucose concentrations increased the occurrence of stress-induced senescence of notochordal cells by p16-pRB pathways at 1 and 3 days. CONCLUSIONS: Despite compensatory expression of antioxidants, high glucose-induced oxidative stress accelerates stress-induced senescence in rat notochordal cells. This may result in dysfunction of notochordal cells, leading to accelerated premature disc degeneration. The prevention of excessive generation of oxidative stress by strict blood glucose control is important to prevent or to delay premature disc degeneration in young patients with diabetes mellitus.

Estrogen exerts the effect on stress-induced senescence of vascular smooth muscl cells in vitro / 解剖学报

Objective To explore the effects of estrogen on stress-induced senescence of vascular smooth muscle cells (VSMCs) and the underlying mechanisms. Methods The VSMCs of passage 2-3 cultured from female SD rats were induced into senescence by exposing to 150μmol/L H2O2 in the presence or absence of different concentrations(10-10mol/L-10-8mol/L) of 17β-estradiol (E2). The expressions or activities of senescence associated marker DcR2, senescence-associated beta-galactosidase (SA-β-Gal), oncogene Ras and p21WAF1 were detected by flow cytometry, cytochemical staining, pull-down assay or Western blotting analysis. Results Flow cytometry analysis showed that in the physiological concentrations, E2 significantly inhibited the H2O2-promoted high-level expression of DcR2 of VSMCs in a dose-dependent manner, with a highest inhibitive rate at 14.48%±0.6%(E2=10-8 mol/L;P<0.05, n =3);this inhibitive effect could be blocked by a E2 receptors inhibitor ICI 182,780. Cytochemistry staining showed that the rate of SA-β-Gal positive VSMCs induced by H2O2 decreased in presence of 10-8mol/L E2 (20.5%±1.4% vs 9.6%±0.9%;P<0.05, n =9). Pull-down assay and Western blotting analysis revealed that administration of 10-8mol/L E2 obviously reduced the H2O2-induced activity of Ras (0.60±0.06 vs 0.26±0.04;P<0.05, n =3) and expression of p21WAF1 (0.46±0.04 vs 0.33±0.02;P<0.05, n =3). Conclusion E2 exerts, an inhibitive effects on stress-induced senescence of VSMCs by suppressing the activity of Ras and expression of p21WAF1. This finding suggests a novel mechanism for the hormone's anti-atheroschlerotic effects.