Phellopterin Drives Apoptosis in A549 Lung Cancer Cells via Caspase-3 Activation and BCL2 Suppression While Activating NRF2/NF-κB Cytoprotective Pathways in BEAS-2B Normal Cells

LI et al.: DUAL APOPTOTIC AND CYTOPROTECTIVE EFFECTS OF PHELLOPTERIN

Abstract

Phellopterin, a naturally occurring furanocoumarin, has attracted interest as a potential anticancer compound because it can differentially modulate redox and apoptotic signaling pathways. This study investigated the tumor-selective effects of phellopterin in human lung adenocarcinoma A549 cells compared with normal human bronchial epithelial BEAS-2B cells using a focused mechanistic approach. Cells were treated with 25 μM phellopterin for 24 h to reflect early apoptosis and stress signaling while minimizing cytotoxic effects. Control cells received the vehicle only. Pathway specificity was determined using the caspase-3 inhibitor Z-DEVD-FMK (20 μM) in A549 cells and the NRF2 inhibitor ML385 (5 μM) in BEAS-2B cells for 24 h. BCL2, NRF2, and HO-1 expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR), while NF-κB P65, cleaved caspase-3, interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-α) levels were measured by enzyme-linked immunosorbent assay (ELISA).In A549 cells, phellopterin induced cleaved caspase-3 and decreased BCL2 mRNA expression, activating caspase-dependent apoptosis, which corresponded with reduced TNF-α and IL-6. In BEAS-2B cells, phellopterin did not activate caspase-3 or inhibit BCL2 but enhanced NRF2 activation and increased HO-1 expression. Moderate NF-κB P65 inhibition was observed in BEAS-2B cells, correlating with decreased IL-8. NRF2 inhibition blocked HO-1 upregulation, confirming NRF2-mediated cytoprotective signaling.Phellopterin exerts tumor-selective activity by inducing apoptosis and inflammatory modulation in lung cancer cells while activating antioxidant and anti-inflammatory pathways in normal bronchial epithelial cells, highlighting its potential as a mechanistically targeted therapeutic candidate for lung cancer.