Surgery is the common treatment for early lung cancer with multiple pulmonary nodules, but it is often accompanied by the problem of significant malignancy of other nodules in non-therapeutic areas. In this study, we found that a combined treatment of local radiofrequency ablation (RFA) and melatonin (MLT) greatly improved clinical outcomes for early lung cancer patients with multiple pulmonary nodules by minimizing lung function injury and reducing the probability of malignant transformation or enlargement of nodules in non-ablated areas. Mechanically, as demonstrated in an associated mouse lung tumor model, RFA not only effectively remove treated tumors but also stimulate antitumor immunity, which could inhibit tumor growth in non-ablated areas. MLT enhanced RFA-stimulated NK activity and exerted synergistic antitumor effects with RFA. Transcriptomics and proteomics analyses of residual tumor tissues revealed enhanced oxidative phosphorylation and reduced acidification as well as hypoxia in the tumor microenvironment, which suggests reprogrammed tumor metabolism after combined treatment with RFA and MLT. Analysis of residual tumor further revealed the depressed activity of MAPK, NF-kappa B, Wnt, and Hedgehog pathways and upregulated P53 pathway in tumors, which was in line with the inhibited tumor growth. Combined RFA and MLT treatment also reversed the Warburg effect and decreased tumor malignancy. These findings thus demonstrated that combined treatment of RFA and MLT effectively inhibited the malignancy of non-ablated nodules and provided an innovative non-invasive strategy for treating early lung tumors with multiple pulmonary nodules. Trial registration: www.chictr.org.cn, identifier ChiCTR2100042695, http://www.chictr.org.cn/showproj.aspx?proj=120931.

As an antioxidant, α-lipoic acid (LA) has attracted much attention to cancer research. However, the exact mechanism of LA in cancer progression control and prevention remains to be unclear. In this study, we demonstrated that α-lipoic acid has inhibitory effects on the proliferation, migration, and proapoptotic effects of non-small-cell lung cancer (NSCLC) cell lines A549 and PC9. LA-induced NSCLC cell apoptosis was mediated by elevated mitochondrial reactive oxygen species (ROS). Further study confirmed that it is by downregulating the expression of PDK1 (the PDH kinase), resulted in less phospho-PDH phenotype which could interact with Keap1, the negative controller of NRF2, directly leading to NRF2 decrease. Thus, by downregulating the NRF2 antioxidant system, LA plays a role in promoting apoptosis through the ROS signaling pathway. Moreover, LA could enhance other PDK inhibitors with the proapoptosis effect. In summary, our study shows that LA promotes apoptosis and exerts its antitumor activity against lung cancer by regulating mitochondrial energy metabolism enzyme-related antioxidative stress system. Administration of LA to the tumor-bearing animal model further supported the antitumor effect of LA. These findings provided new ideas for the clinical application of LA in the field of cancer therapy.

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death worldwide. Amygdalin, a natural compound commonly distributed in plants of the Rosaceae species, owns anticancer activity, less side effects, wide source, and relatively low price. Although the apoptosis is a central process activated by amygdalin in cancer cells, the underlying molecular mechanisms through which amygdalin induces the apoptosis of lung cancer cells remain poorly understood. In this research work, amygdalin could suppress the proliferation of lung cancer A549 and PC9 cells by CCK8 assay. Amygdalin significantly promoted the apoptosis of lung cancer A549 and PC9 cells stained with Annexin V-FITC/PI by flow cytometry assay. Furthermore, amygdalin dose-dependently decreased the mitochondrial membrane potential (MMP) with JC-1 dye by flow cytometry. To investigate the underlying molecular mechanisms through which amygdalin induced mitochondria-mediated apoptosis of cancer cells, the differentially-expressed genes with a fold change >2.0 and [Formula: see text] < 0.05 were acquired from the cDNA microarray analysis. The results of qRT-PCR further confirmed that the differentially-expressed level of the NF[Formula: see text]B-1 gene was most obviously enhanced in lung cancer cells treated with amygdalin. The results of immunofluorescence staining, Western blotting and siRNA knockdown indicated that amygdalin induced mitochondria-mediated apoptosis of lung cancer cells via enhancing the expression of NF[Formula: see text]B-1 and inactivating NF[Formula: see text]B signaling cascade and further changing the expressions of proteins (Bax, Bcl-2, cytochrome C, caspase 9, caspase 3 and PARP) related to apoptosis, which were further checked by in vivo study of the lung cancer cell xenograft mice model accompanying with immunohistochemical staining and TUNEL staining. Our results indicated that amygdalin might be a potential activator of NF[Formula: see text]B-1, which sheds more light on the molecular mechanism of anticancer effects of amygdalin. These results highlighted amygdalin as a potential therapeutic anticancer agent, which warrants its development as a therapy for lung cancer.