Leptin-mediated ERK Signaling Pathway Promotes the Transformation of Rat Alveolar Type II Epithelial Cells Induced by Yunnan Tin Mine Dust / 中国肺癌杂志

BACKGROUND@#Currently, a significant number of miners are involved in mining operations at the Gejiu tin mine in Yunnan. This occupational setting is associated with exposure to dust particles, heavy metals, polycyclic aromatic hydrocarbons, and radioactive radon, thereby significantly elevating the risk of lung cancer. This study aims to investigate the involvement of leptin-mediated extracellular regulated protein kinase (ERK) signaling pathway in the malignant transformation of rat alveolar type II epithelial cells induced by Yunnan tin mine dust.@*METHODS@#Immortalized rat alveolar cells type II (RLE-6TN) cells were infected with Yunnan tin mine dust at a concentration of 200 μg/mL for nine consecutive generations to establish the infected cell model, which was named R₂₀₀ cells. The cells were cultured normally, named as R cells. The expression of leptin receptor in both cell groups was detected using the Western blot method. The optimal concentration of leptin and mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) on R₂₀₀ cells was determined using the MTT method. Starting from the 20th generation, the cells in the R group were co-cultured with leptin, while the cells in the R₂₀₀ group were co-cultured with the MEK inhibitor U0126. The morphological alterations of the cells in each group were visualized utilizing hematoxylin-eosin staining. Additionally, concanavalin A (ConA) was utilized to detect any morphological differences, and an anchorage-independent growth assay was conducted to assess the malignant transformation of the cells. The changes in the ERK signaling pathway in epithelial cells after the action of leptin were detected using the Western blot method.@*RESULTS@#Both the cells in the R group and R₂₀₀ group express leptin receptor OB-R. Compared to the R₂₀₀ group, the concentration of leptin at 100 ng/mL shows the most significant pro-proliferation effect. The proliferation of R₂₀₀ cells infected with the virus is inhibited by 30 μmol/L U0126, and a statistically significant divergence was seen when compared to the control group (P<0.05). Starting from the 25th generation, the cell morphology of the leptin-induced R₂₀₀ group (R₂₀₀L group) underwent changes, leading to malignant transformation observed at the 30th generation. The characteristics of malignant transformation became evident by the 40th generation in the R₂₀₀L group. In contrast, the other groups showed agglutination of P40 cells, and the speed of cell aggregation increased with an increase in ConA concentration. Notably, the R₂₀₀L group exhibited faster cell aggregation compared to the U0126-induced R₂₀₀ (R₂₀₀LU) group. Additionally, the cells in the R₂₀₀L group were capable of forming clones starting from P30, with a colony formation rate of 2.25‰±0.5‰. However, no clonal colonies were observed in the R₂₀₀LU group and R₂₀₀ group. The expression of phosphorylated extracellular signal-regulated kinase (pERK) was enhanced in cells of the R₂₀₀L group. However, when the cells in the R₂₀₀L group were treated with U0126, a blocking agent, the phosphorylation level of pERK decreased.@*CONCLUSIONS@#Leptin can promote the malignant transformation of lung epithelial cells infected by mine dust, and the ERK signaling pathway may be necessary for the transformation of alveolar type II epithelial cells induced by Yunnan tin mine dust.

Study on the role of CCL19 and AKT signaling pathway in the development of lung cancer / 中国职业医学

Objective To investigate the role of chemokine ligand 19 (CCL19) and protein kinase-B (AKT) signaling pathway in lung cancer development. Methods The human lung adenocarcinoma cell line, A549 cells, in logarithmic growth phase were randomly divided into five groups： blank control group, solvent control group, CCL19 treatment group, AKT inhibition group, and antibody neutralization group. The blank control group received no treatment. The other four groups were treated with dimethyl sulfoxide, CCL19, MK-2206 (AKT inhibitor), and a combination of CCL19 and MK-2206, respectively. Cell viability was assessed using the CCK-8 assay, while cell migration and invasion capabilities were evaluated using the cell scratch and transwell assays. The relative expression levels of Pan-AKT, p-AKT (Ser473), p-AKT (Thr308), E-cadherin (E-cad), N-cadherin (N-cad), and Snail proteins in A549 cells were detected using Western blotting. Lung cancer tissue samples from 60 patients with non-small cell lung cancer (NSCLC) were collected, and the expression of CCL19 and matrix metalloproteinase 9 (MMP9) proteins in the specimens was examined using immunohistochemistry. Results The survival rate of A549 cells in the AKT inhibition group and antibody neutralization group was lower than that in blank control group, solvent control group, and CCL19 treatment group (all P<0.05). The cell scratch assay result showed that the cell migration rate of the CCL19 treatment group was higher at 36.0 and 48.0 hours than those of the blank control group, solvent control group, AKT inhibition group, and neutralizing antibody group (all P<0.05). The Transwell assay result showed that the invasion amount of A549 cells in the AKT inhibition group was less than that in the CCL19 treatment group (P<0.05). Compared with the blank control group, the relative expression of E-cad protein in the CCL19 treatment group decreased, while the relative expression of p-AKT (Ser473), p-AKT (Thr308), N-cad and Snail proteins increased (all P<0.05). The relative expression of p-AKT (Ser473), p-AKT (Thr308), N-cad, and Snail proteins in A549 cells decreased (all P<0.05), and relative expression of E-cad protein increased (all P<0.05) in the AKT inhibition group and antibody neutralization group compared with the blank control group, solvent control group, and CCL19 treatment group. There was no significant difference in the expression of CCL19 and MMP9 in lung cancer tissues of NSCLC patients in Xuanwei City, Gejiu City, and other regions (all P>0.05). The expression of CCL19 and MMP9 in NSCLC patients with lymph node metastasis was higher than in patients without lymph node metastasis (all P<0.01). Conclusion CCL19 can promote the invasion and metastasis of lung cancer cells and induce epithelial-mesenchymal transition. Its expression level is related to lymph node metastasis in NSCLC patients. The AKT signaling pathway may be an important mechanism underlying lung cancer development.