A natural flavonoid, apigenin isolated from Clerodendrum viscosum leaves, induces G2/M phase cell cycle arrest and apoptosis in MCF-7 cells through the regulation of p53 and caspase-cascade pathway

Background With 9.6 million deaths in 2018, cancer remains the second leading cause of death worldwide. Breast cancer is the most deadly type of cancer among females, with 55.2% of crude incidence rate and 16.6% of crude mortality rate. Purpose The present study was aimed to investigate the anti-breast cancer potential of natural dietary flavonoid, apigenin isolated from Clerodendrum viscosum leaves. Methods Apigenin was evaluated for in-depth anticancer activity in MCF-7 cells using cell viability assay, cell cycle analysis, Annexin-V-FLUOS staining, ROS induction, morphological analysis, and western blot analysis. Results Apigenin showed selective cytotoxicity on MCF-7 cells with an IC50-56.72 ± 2.35 µM, while negligible cytotoxicity was observed on WI-38 cells. Further, the flow cytometer-based analysis showed that apigenin halted MCF-7 cells in the G2/M phase arrest followed by dose-dependent apoptosis. Moreover, the FACS and confocal microscopy results confirmed the elevation of intracellular ROS and nuclear fragmentation in apigenin-treated MCF-7 cells. Western blots showed up-regulation of cell cycle regulatory proteins, increased p53 expression, Bax/Bcl-2 ratio, activation of caspases, and cleavage of PARP. Finally, apigenin treatment in the presence of Pifithrin-µ showed decreased apoptotic population and it was further confirmed through western blotting study. The results revealed the vital role of p53 in apigenin-induced apoptosis in MCF-7 cells. Conclusions In the present findings, treatment of apigenin-induced intracellular ROS in MCF-7 cells followed by induction of G2/M phase cell cycle arrest and further apoptosis through the regulation of p53 and caspase-cascade signaling pathway (AU)

Tropical lichen, Dirinaria consimilis, induces ROS-mediated activation of MAPKs and triggers caspase cascade mediated apoptosis in brain and cervical cancer cells.

Lichens are the symbiotic association between photobiont algae and mycobiont fungi having diverse phytochemicals. However, they are still an underexplored natural resource for biological activities. In the present report, we have evaluated the anti-brain and anti-cervical cancer activity of tropical lichen, Dirinaria consimilis (DCME) through the cell viability assay, cell cycle analysis, annexin V-FLUOS staining, morphological analysis, ROS-induction mechanism, evaluation of antioxidant levels, and western blotting study. The WST-1-based cell viability assay showed the cytotoxic nature of DCME towards U87 (IC50-52.65 ± 1.04 µg/ml) and HeLa (IC50-77.60 ± 2.23 µg/ml) cells. Interestingly, DCME does not showed any toxicity towards non-malignant fibroblast cell line WI-38 (IC50-685.80 ± 19.51 µg/ml). Furthermore, the cell cycle analysis showed sub-G1 arrest (apoptosis), and annexin V-FLUOS staining showed an increase in early apoptosis population dose-dependently. Confocal-based morphological data confirmed the DNA condensation and fragmentation upon treatment. Furthermore, DCME treatment induces ROS and regulates the levels of antioxidant enzymes (SOD, Catalase, GST, and GSH) in both U87 and HeLa cells. Finally, the western blotting data revealed the increase in Bax/Bcl-2 ratio, activation of Bid, Caspase-8, -9 and -3 along with degradation of PARP. Moreover, regulation of MAP kinases and activation of p53 was also observed upon DCME treatment. Herein, we first reported the anticancer activity of D. consimilis against brain and cervical cancer cells. Performed in-depth anticancer study revealed the ROS-mediated regulation of MAP kinases and activation of caspase cascade in U87 and HeLa cells upon DCME treatment.

The natural flavones, acacetin and apigenin, induce Cdk-Cyclin mediated G2/M phase arrest and trigger ROS-mediated apoptosis in glioblastoma cells.

Brain and CNS-related cancers are rare; however, 0.3 million incidences and 0.24 million deaths in 2018 demonstrates the unrelenting associated dangers. Glioblastoma is a brain cancer of star-shaped glial cells. It is almost universally fatal within 2 years of diagnosis despite maximal medical therapies. This study aims to evaluate the in-depth anticancer activity of acacetin and apigenin on glioblastoma cells (U87). In the present report, we have isolated two flavonoids, acacetin and apigenin; and studied the in-depth anticancer activity on U87 cells. Selective cytotoxicity of acacetin and apigenin was observed towards the U87 cells (IC50: 43.73 ± 1.19 and 48.18 ± 1.37 µM, respectively). The flow cytometer-based result revealed the induction of G2/M phase arrest along with the increase in sub G1 population upon compound treatment. Annexin-V-FLUOS and DAPI staining also confirmed the apoptosis-inducing effects of compounds. Flow cytometer and confocal microscopy-based DCFH-DA staining showed ROS-inducing effect of the compounds. The up-regulation of p21 and down-regulation of Cyclin-A1, Cyclin-B1, and Cdk-1 revealed the G2/M phase arrest mechanism of acacetin and apigenin. Furthermore, western blotting result confirmed the activation of intrinsic pathway of apoptosis upon acacetin treatment and activation of both extrinsic and intrinsic pathways of apoptosis upon apigenin treatment through the regulation of Bax, t-Bid, caspase 8, caspase 9, caspase 3, and PARP. The obtained result showed a significant effect (P < 0.05) of acacetin and apigenin on U87 cells. Acacetin and apigenin-induced ROS is responsible for the induction of cell cycle arrest and activation of caspase-cascade pathways in U87 cells.

A natural flavonoid, apigenin isolated from Clerodendrum viscosum leaves, induces G2/M phase cell cycle arrest and apoptosis in MCF-7 cells through the regulation of p53 and caspase-cascade pathway.

BACKGROUND: With 9.6 million deaths in 2018, cancer remains the second leading cause of death worldwide. Breast cancer is the most deadly type of cancer among females, with 55.2% of crude incidence rate and 16.6% of crude mortality rate. PURPOSE: The present study was aimed to investigate the anti-breast cancer potential of natural dietary flavonoid, apigenin isolated from Clerodendrum viscosum leaves. METHODS: Apigenin was evaluated for in-depth anticancer activity in MCF-7 cells using cell viability assay, cell cycle analysis, Annexin-V-FLUOS staining, ROS induction, morphological analysis, and western blot analysis. RESULTS: Apigenin showed selective cytotoxicity on MCF-7 cells with an IC50-56.72 ± 2.35 µM, while negligible cytotoxicity was observed on WI-38 cells. Further, the flow cytometer-based analysis showed that apigenin halted MCF-7 cells in the G2/M phase arrest followed by dose-dependent apoptosis. Moreover, the FACS and confocal microscopy results confirmed the elevation of intracellular ROS and nuclear fragmentation in apigenin-treated MCF-7 cells. Western blots showed up-regulation of cell cycle regulatory proteins, increased p53 expression, Bax/Bcl-2 ratio, activation of caspases, and cleavage of PARP. Finally, apigenin treatment in the presence of Pifithrin-µ showed decreased apoptotic population and it was further confirmed through western blotting study. The results revealed the vital role of p53 in apigenin-induced apoptosis in MCF-7 cells. CONCLUSIONS: In the present findings, treatment of apigenin-induced intracellular ROS in MCF-7 cells followed by induction of G2/M phase cell cycle arrest and further apoptosis through the regulation of p53 and caspase-cascade signaling pathway.