Lung cancer is the most common malignant tumor in China. It often metastasizes to bone, thereby significantly shortening the lives of patients, and reducing their quality of life. However, the efficacy of treatment for bone metastasis of lung cancer at this stage is very limited. The development and clinical application of molecular-targeted drugs for the effective targeted therapy of bone metastasis of lung cancer are urgently required. The growth differentiation factor 15 (GDF15) gene which may be associated with bone metastasis of lung cancer, was screened out by whole-genome sequencing. In the present study, we used a recombinant GDF15 lentivirus technique to upregulate the expression of GDF15 in lung adenocarcinoma A549 cells, and the results revealed that GDF15 could inhibit the proliferation, migration and invasion, while promoting apoptosis of A549 cells. In addition, GDF15 significantly decreased the number and sites of lung metastases and bone metastases in vivo compared to the control group. Finally, it was revealed that Smad2 and phospho-Smad2 protein expression was lower in the GDF15-overexpressing A549 cells. This result indicated that the tumor suppressive effect of GDF15 may be related to the TGF-β/Smad signaling pathway, although more studies are still required for confirmation. In summary, GDF15 inhibited the growth and bone metastasis of lung adenocarcinoma A549 cells, and this effect may be achieved through the TGF-β/Smad signaling pathway.

BackgroundIt is known that γ‐glutamyl hydrolase (GGH) is involved in the disposition of methotrexate (MTX), and GGH activity is regulated by DNA methylation in acute lymphoblastic leukemia (ALL) cells. The present study explores the methylation status of the GGH promoter in peripheral blood and its association with MTX levels and toxicities in Chinese children with ALL.MethodsSerum MTX concentrations were determined by fluorescence polarization immunoassay. Methylation quantification and genotyping for GGH rs3758149 and rs11545078 was performed by Sequenom MassARRAY in 50 pediatric patients with ALL.ResultsOverall, the investigated region of the GGH promoter was in hypomethylated status. The methylation levels of cytosine phosphate guanine (CpG)_7, CpG_12, CpG_17, and CpG_20 were significantly higher in patients with B‐cell ALL than other immunotypes (p<0.05). The methylation levels of CpG_13.14, CpG_17, and CpG_19 showed a significant negative correlation with MTX C24 hr (p<0.05). The methylation level of CpG_8.9 correlated significantly with MTX C42 hrs (p<0.05). The methylation level of CpG_19 was significantly lower in patients with MTX toxicities (p<0.05).ConclusionsThe methylation levels of the GGH promoter might affect MTX exposure and toxicities. These findings provided reasonable explanations for the variability of MTX responses in patients with childhood ALL.

The results of this study confirmed the significant ethnic differences in the distributions of the TYMS rs2790 A > G polymorphism. Whereas there was evidence of differences in MTX blood levels according to genotype, our study was not powered to show whether this would lead to more haematological toxicity.