Study On The Mechanism Of 3-nitrofluoranthene Exposure Promoting Tumor Stem Cells In Lung Cancer

The rapid development of China’s economy is accompanied by the emergence of environmental pollution problems.At present,PM_2.5 pollution has become one of the most important environmental factors affecting human health.Many studies have confirmed that PM_2.5 exposure can promote cancer.Nitro polycyclic aromatic hydrocarbons（NPAHs）,the main organic component in PM_2.5,have carcinogenicity and mutagenicity,and their carcinogenic and mutagenic potential is 10-100000 times higher than their corresponding parent polycyclic aromatic hydrocarbons,significantly enhancing the toxicity of PM_2.5.Lung cancer stem cells（LCSCs）are the main cause of lung cancer treatment failure that leads to the occurrence,metastases and recurrence of lung cancer.Currently,the research on the mechanism of NPAHs exposure promoting lung cancer stem cells（LCSCs）in lung cancer is not sufficient.Therefore,exploring the occurrence and mechanism of biological characteristics of LCSCs induced by exposure to typical NPAHs in PM_2.5 is an important way to further uncover the toxic mechanism of PM_2.5.In this study,we selected typical NPAHs 3-nitrofluoranthene（3-NF）in PM_2.5 as the pollutant,and human lung cancer epithelial cell A549 as the research object.A549cells were exposed to 10μM 3-NF to detect the changes in cloning ability,tumor spheroid formation,and m RNA and protein expression levels of LCSCs markers in A549 cells after 3-NF exposure.The results showed that 3-NF exposure significantly enhanced the cloning ability and promoted the formation of tumor spheres in A549 cells.The expression level of LCSCs markers labeled m RNA and protein in A549 cells were also significantly up-regulated after 3-NF exposure.The mechanism of 3-NF exposure promoting LCSCs in lung cancer was further explored through sh RNA lentivirus transfection technology.The results showed that 3-NF exposure significantly enhanced the expression level of IGF1R signal pathway related factors.After stable interference with IGF1R expression using sh RNA lentivirus transfection technology,compared with 3-NF exposure group,the clonogenic ability of A549 cells,tumor spheroid formation,and expression levels of LCSCs markers m RNA and protein in sh-IGF1R+3-NF group were significantly decreased;At the same time,the protein expression of IGF1R,P-IGF1R,and P-STAT3 in A549 cells of sh-IGF1R+3-NF group was significantly inhibited.Finally,the interaction mode between small molecule ligand 3-NF and IGF1R receptor protein was investigated using computer simulation molecular docking method.The results showed that 3-NF could enter the active cavity of IGF1R receptor protein and bind to IGF1R through different types of hydrophobic forces,and the complex of3-NF and IGF1R showed a stable trend during the entire interaction process.In summary,this study found that 3-NF exposure promotes changes in the biological characteristics of LCSCs in lung cancer and upregulates the expression of lung cancer stem cell markers.The mechanism may be related to the stable binding of3-NF to IGF1R receptor proteins and the regulation of activation of IGF/IGF1R/STAT3signaling pathways.This study revealed the tumor stem cell mechanism of typical NPAHs 3-nitrofluoranthene（3-NF）in PM_2.5 in promoting lung cancer,and the results are expected to provide a reference basis for analyzing the toxic mechanism of PM_2.5,population health protection against air pollution,and health risk assessment.