瘦素/ERK信号在云锡矿粉诱导大鼠II型肺泡上皮细胞转化中的作用

BACKGROUND AND OBJECTIVE: 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 R(200) 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 R(200) cells was determined using the MTT method. Starting from the 20(th) generation, the cells in the R group were co-cultured with leptin, while the cells in the R(200) 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 R(200) group express leptin receptor OB-R. Compared to the R(200) group, the concentration of leptin at 100 ng/mL shows the most significant pro-proliferation effect. The proliferation of R(200) 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 25(th) generation, the cell morphology of the leptin-induced R(200) group (R(200)L group) underwent changes, leading to malignant transformation observed at the 30(th) generation. The characteristics of malignant transformation became evident by the 40(th) generation in the R(200)L 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 R(200)L group exhibited faster cell aggregation compared to the U0126-induced R(200) (R(200)LU) group. Additionally, the cells in the R(200)L 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 R(200)LU group and R(200) group. The expression of phosphorylated extracellular signal-regulated kinase (pERK) was enhanced in cells of the R(200)L group. However, when the cells in the R(200)L group were treated with U0126, a blocking agent, the phosphorylation level of pERK decreased. CONCLUSION: 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.