Figure 1. Transcriptome analysis identifies SERPINB3 as a marker upregulated in basal-like/squamous PDAC and associated with poor survival.

(A) Strategy to find candidate driver genes of the basal-like/squamous subtype in PDAC. Two cohorts (Bailey³ and Moffitt⁴) were interrogated to identify candidate driver genes of the basal-like/squamous subtype. The genes were narrowed down to those associated with patient survival in the NCI-UMD-German cohort.¹⁷ Data are presented as the mean ± SD. *p < 0.05, ***p < 0.005 by unpaired two-tailed Student’s t test.

(B–D) Comparison of SERPINB3 transcript and protein expression levels in PDAC tumors versus adjacent noncancerous tissues, revealing upregulation of SERPINB3 in tumors in both the NCI-UMD-German cohort (mRNA via qPCR and protein via IHC) and the validation cohort (Moffitt cohort⁴; GSE71729; mRNA). Data are presented as the mean ± SD. ***p < 0.005 by unpaired two-tailed Student’s t test. The bottom shows Kaplan-Meier plots and log-rank test results, highlighting the association of increased SERPINB3 expression with decreased PDAC patient survival. For the survival analysis in the NCI-UMD-German cohort (B and D), the comparison was conducted between patients in the upper and lower 50% of SERPINB3 levels. In the validation cohort (C), patients in the upper and lower tertiles of SERPINB3 expression were compared (total patient number = 125). The right side shows IHC of SERPINB3 in representative nontumor (score 0) and tumor tissues (scores 1–3). SERPINB3 protein was detected in both the nucleus and the cytoplasm, as shown by the brown DAB-based IHC in the tumor cells. The images show the staining strength (score 0, unstained; score 1, weak; score 2, moderate; score 3, strong). Scale bars, 20 μm. More details can be found in the STAR Methods. IHC, immunohistochemistry. See also Tables S1 and S2.