Fig. 6

Negative correlation between elevated MUC21 expression and immune cytotoxicity in LUAD. (A) Expression levels of the MUC21 gene in LUAD and LUSC patients from TCGA, along with their matched normal individuals from TCGA and GTEx. This analysis considered both the disease subtype and progression. Statistical significance was assessed using one-way ANOVA and a Dunnett’s multiple comparison test. (B) Heatmap illustrating the Pearson correlation coefficients between the gene expression levels of each member of the mucin family in TCGA LUAD samples. (C) Heatmap displaying scores representing the infiltration of NK cells, CD8⁺T cells, and CD4⁺T cells based on different immune cell deconvolution methods in TCGA LUAD. (D) Progression-free survival curve of lung cancer patients (LUAD and LUSC) from TCGA plotted based on the expression of the MUC21 gene. The Kaplan-Meier curve compares the top and bottom quartiles of MUC21 expression, and significance was evaluated using log-rank test statistics. (E) Scatter plots depicting the correlations between the expression of the MUC21 gene and cytotoxicity genes (IFNG, PRF1, GZMA, and GZMB) involved in NK/T cell-mediated cytotoxic responses in TCGA LUAD. The correlation was tested using a Spearman’s rank correlation coefficient. (F) Boxplots comparing the expression of the MUC21 gene between patients who responded to anti-PD-(L)1 immune checkpoint inhibitor therapy and those who did not respond in two different lung cancer cohorts. Responders (R) or those with durable clinical benefit (DCB) achieved partial response (PR) or stable disease (SD) for more than six months. Non-responders (NR) or those with non-durable benefit (NDB) experienced progressive disease (PD) or SD for less than six months. The significance of the differences was evaluated using a Student’s t-test