Effects of UV on apoptotic factors in lens epithelial cells of an animal model

Epigallocatechin gallate enhances human lens epithelial cell survival after UVB irradiation via the mitochondrial signaling pathway

The aim of the present study was to explore the mechanism underlying the ultraviolet B (UVB) irradiation-induced apoptosis of human lens epithelial cells (HLECs), and to investigate the protective effect of epigallocatechin gallate (EGCG) against the UVB-induced apoptosis of HLECs. HLECs were exposed to different concentrations of EGCG plus UVB (30 mJ/cm²). Cell viability was determined using the MTT assay. Furthermore, mitochondrial membrane potential (Δψm) and apoptosis were assessed by flow cytometry with JC-1 and Annexin V/PI staining, respectively. Moreover, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), as well as the levels of GSH, hydrogen peroxide (H₂O₂) and hydroxyl free radicals were determined using biochemical assay techniques. Reverse transcription-quantitative PCR and western blotting were used to detect the mRNA and protein expression levels of Bcl-2, Bax, cytochrome c, caspase-9 and caspase-3, respectively. The results revealed that UVB irradiation reduced the Δψm of HLECs and induced apoptosis. Notably, EGCG significantly attenuated the generation of H₂O₂ and hydroxyl free radicals caused by UVB irradiation in HLECs, and significantly increased CAT, SOD and GSH-Px activities, however, the GSH levels were not significantly increased. EGCG also reduced UVB-stimulated Bax, cytochrome c, caspase-9 and caspase-3 expression, and elevated Bcl-2 expression, suggesting that EGCG may possess free radical-scavenging properties, thus increasing cell viability. In conclusion, EGCG may be able to protect against UVB-induced HLECs apoptosis through the mitochondria-mediated apoptotic signaling pathway, indicating its potential application in clinical practice.

Cytotoxic Property of Grias neuberthii Extract on Human Colon Cancer Cells: A Crucial Role of Autophagy

Traditional herbal medicine has become an important alternative in the treatment of various cancer types, including colon cancer, which represents one of the main health problems around the world. Therefore, the search for new therapies to counteract this disease is very active. Grias neuberthii is an endemic plant located in the Ecuadorian Amazon region, which has been used in traditional medicine for its pharmacological properties, including its ability to inhibit tumor cell growth, although scientific studies are limited. We have analyzed the effect of this plant on two colon carcinoma cell lines, that is, RKO (normal p53) and SW613-B3 (mutated p53) cells. Among several extracts obtained from various parts of G. neuberthii plant, we identified the extract with the greatest cytotoxic potential, derived from the stem bark. The cytotoxic effect was similar on both cell lines, thus indicating that it is independent of the status of p53. However, significant differences were observed after the analysis of colony formation, with RKO cells being more sensitive than SW613-B3. No evidence for apoptotic markers was recorded; nevertheless, both cell lines showed signs of autophagy after the treatment, including increased Beclin-1 and LC3-II and decreased p62. Finally, three chemical compounds, possibly responsible for the effect observed in both cell lines, were identified: lupeol (1), 3′-O-methyl ellagic acid 4-O-β-D-rhamnopyranoside (2), and 19-α-hydroxy-asiatic acid monoglucoside (3).