ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.

ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.