CBD boosts paclitaxel against lung cancer in preclinical tests

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide, driven in part by persistent activation of pro-survival pathways such as STAT3 and NF-κB. Cannabidiol (CBD), a non-psychoactive phytocannabinoid, has emerged as a potential anti-cancer agent; however, its mechanisms in NSCLC remain incompletely defined. In particular, CBD has not been systematically investigated for its ability to simultaneously suppress both constitutive and inducible STAT3/NF-κB activation, while coordinating apoptosis and autophagy in NSCLC. Furthermore, its role as a chemosensitizer in combination with paclitaxel remains to be validated in vivo. Human NSCLC cell lines (A549, PC9, and H1299) were treated with cannabidiol (CBD), alone or in combination with paclitaxel. Apoptosis and autophagy were evaluated via caspase-3/7 activity, Western blotting, and immunocytochemistry. The effects of CBD on STAT3 and NF-κB signaling were assessed using EMSA, luciferase reporter assays, and nuclear translocation analysis. Anti-tumor efficacy was further validated in a xenograft mouse model. Here, we demonstrate that CBD reduced cell viability in NSCLC cells (A549 and PC9), while showing less cytotoxicity in normal lung fibroblasts. Mechanistically, CBD induced apoptosis and autophagy and suppressed STAT3 and NF-κB activation at the levels of phosphorylation, nuclear localization, and transcriptional activity. These effects were also observed in inducible signaling models using IL-6-stimulated H1299 cells. Importantly, CBD enhanced the efficacy of paclitaxel, a commonly used chemotherapeutic agent, by synergistically inducing apoptosis and autophagy and further suppressing STAT3/NF-κB signaling. In a xenograft mouse model, CBD treatment significantly reduced tumor growth without affecting body weight, and combination therapy with paclitaxel led to the most pronounced tumor suppression. Tumor tissue analyses confirmed that CBD downregulated phosphorylated STAT3 and p65, reduced proliferation marker Ki-67, and increased expression of cleaved PARP, LC3 II, and other cell death-associated proteins. Our findings provide preclinical evidence that CBD exerts potent anti-tumor activity in NSCLC by coordinating inhibition of oncogenic signaling and activation of programmed cell death pathways. To our knowledge, this study provides evidence that CBD concurrently inhibits STAT3 and NF-κB signaling, affecting both constitutive and inducible activation in NSCLC, and enhances paclitaxel efficacy in vivo, thereby establishing a novel mechanistic and translational basis for its therapeutic potential. These results support the therapeutic effect of CBD as a potential adjuvant in lung cancer treatment.