Objective:To investigate the characteristics of pathogen spectrum and the clinical significance of bronchoalveolar lavage fluid(BALF)metagenomic next-generation sequencing(mNGS)in malignant tumor patients with pulmonary infections.Methods:A retrospective analysis was performed for the patients with malignant tumor who were admitted to department of oncology,the Second affiliated hospital of army medical university,from January 2021 to December 2024.All patients developed respiratory symptoms dur-ing treatment and were diagnosed with pulmonary inflammation based on lung imaging findings,and BALF mNGS and sputum cul-ture were used for pathogen detection.A descriptive analysis was used to summarize the clinical data of patients and the distribution of pathogens,which was compared between patients with different cancer types and metastatic statuses.BALF mNGS and sputum cul-ture were compared in terms of diagnostic performance.Results:A total of 127 patients were enrolled,among whom 70.9%had non-small cell lung cancer,15.0%had small cell lung cancer,and 14.1%had other malignancies.The patients with distant metastasis ac-counted for 48.0%.A total of 145 BALF mNGS tests were performed,among which 84 tests(57.9%)yielded positive results for patho-gens,and 13 tests detected polymicrobial infections,accounting for 15.5%(13/84).A total of 121 pathogenic strains were identified,with fungi(41.3%)and Gram-negative bacteria(39.7%)as the main pathogens,and common pathogens for infection included Pneumo-cystis jirovecii(16.5%),Candida albicans(11.6%),Haemophilus influenzae(11.6%),Klebsiella pneumoniae(10.7%),Pseudomonas ae-ruginosa(10.7%),and Staphylococcus aureus(8.3%).There was a significant difference in the distribution of pathogens between the pa-tients with different types of cancer and statuses of distant metastasis,but Pneumocystis jirovecii remained the most common pathogen for opportunistic infection across all subgroups.A total of 70 patients underwent both sputum culture and BALF mNGS,and the posi-tive rate of sputum culture was only 16.0%,which was significantly lower than that of BALF mNGS(χ2=35.52,P<0.001).The concor-dance rate between sputum culture and BALF mNGS was 48.1%.Conclusion:BALF mNGS can accurately reveal the complex patho-gen spectrum in malignant tumor patients with pulmonary infections,especially the high-risk opportunistic pathogens such as Pneumo-cystis jirovecii.For patients with negative results of sputum culture,BALF mNGS can significantly improve the detection rates of patho-gens and polymicrobial infections.

Objective To explore the mechanism and effects of Basonuclin 1(BNC1)on the migration and invasion abilities of lung squamous cell carcinoma.Methods Bioinformatics technology was used to analyze the expression patterns and survival impact of BNC1 in patients with lung squamous cell carcinoma in online databases;Tissue microarrays were stained by immunohistochemistry assay and analyzed for BNC1 protein level.Cell lines for lung squamous cell carcinoma with high and low BNC1 expression were screened in the Cancer Cell Line Encyclopedia(CCLE)database.Wound healing experiment and transwell assay were performed on lung squamous cell carcinoma cell models with knockdown and overexpression of BNC1,and the migration and invasion rates of each cell line were detected;Quantitative reverse transcription PCR(RT-qPCR)was used to validate the migration and invasion of 10 highly related genes derived from literature.Western blotting was used to validate the selected regulatory genes.Results Bioinformatics technology found that BNC1 was highly expressed in lung squamous cell carcinoma tissues and was associated with lower survival rate(P=0.047).The expression of BNC1 in lung squamous cell carcinoma was higher than that in paracancerous tissues(P＜0.05).BNC1 had higher expression in the H226 cells and lower expression in the SK-MES1 cells.BNC1 knockdown inhibited the migration and invasion abilities of lung squamous cell carcinoma cells(P＜0.05),and BNC1 overexpression enhanced the migration and invasion abilities of lung squamous cell carcinoma cells(P＜0.05).Screening of BNC1 downstream regulatory molecules at the mRNA level showed that CDH1 was decreased when BNC1 was overexpressed(P＜0.05),and increased when BNC1 was knocked down(P＜0.05).The results of mRNA level were consistent with the results verified by Western blotting(P＜0.05).Conclusion BNC1 may be a gene predicting poor prognosis for lung squamous cell carcinoma patients,and BNC1 may likely to promote cell migration and invasion of lung squamous cell carcinoma by downregulating CDH1 expression.