Haberlea rhodopensis alcohol extract normalizes stress-responsive transcription of the human TP53 gene

Abstract

The Orpheus flower Haberlea rhodopensis (Friv.) of the family Gesneriaceae can go into anabiosis for long periods in an almost entirely desiccated state. It is an endemic relict from the Balkan Peninsula. Alcohol extracts from H. rhodopensis contain many biologically active substances with potent antioxidant, antigenotoxic, radioprotective, revitalizing and antiaging capabilities. However, regulating the gene networks responsible for these activities is vastly unknown. This study explores the cellular mechanisms underlying the protective effect of H. rhodopensis extracts (HRE). HeLa cells (human cervix epithelial carcinoma, HeLa ATCC® CCL-2™) were used as a model. We examined the changes in catalase activity and TP53 mRNA level shortly after oxidative (H2O2) and ionizing radiation (IR) induced stress with and without pre-incubation with HRE extracts. The dynamics in the activity of catalase, a main cellular antioxidant enzyme, and the expression of the stress-responsive gene TP53 were investigated by UV spectrophotometric assay and RT-qPCR, respectively. Under the applied stress conditions, H2O2 treatment and gamma radiation, catalase activity increased. This was a sign of induced ROS generation. In the first hours after treatment, the two stressors led to opposite changes in the levels of TP53 gene expression, which were alleviated by pre-incubation with HRE in a concentration-dependent manner. The broad biological activities of the studied extract, taking into account our results, show that ability of HRE to reduce the effect of stress is achieved through complex molecular mechanisms aimed at preserving cellular homeostasis. Mechanisms include the normalization of antioxidant enzyme activity such as catalase and the activity of TP53, one of the genes responsive to stress, by up or down-regulation.