## 4 Discussion
At mRNA, but not protein level, high expression of _CTNNB1_ was associated with features of biological aggressiveness, including high grade, increased T stage and advanced TMN stage. Kaplan-Meier survival analysis of our dataset showed that there was a suggestive association between high \(\beta\)-catenin expression and shorter survival of PDAC patients (274 vs. 450 days; \(p=0.09\)). In the TCGA cohort, this association was statistically significant (592 vs. 2182 days; \(p=0.001\)). Nevertheless, neither protein nor mRNA expression of \(\beta\)-catenin was an independent prognostic factor when considering confounding factors, including age, tumor stage and LVI. [PERSON] et al. showed that a high IHC score for \(\beta\)-catenin correlated with a poor prognosis, but the researchers evaluated nuclear expression in tissues from PDAC patients and did not perform th multivariate analysis [48]. The opposite relationship regarding \(\beta\)-catenin protein expression and patient survival was presented by [PERSON] et al.,however, due to the difficulty in evaluating membrane and cytoplasm staining separately, the authors of the cited results assessed only cytoplasmic expression pattern [13]. In our investigation, we also found positive associations between the expression of \(\beta\)-catenin and SMAD3, both in our cohort and TCGA cohort. Furthermore, SMAD3 expression was significantly higher in PDAC specimens as compared to control tissues both at mRNA and protein levels, which is consistent with the report of [PERSON] et al. [49]. Furthermore, our analyses showed that patients with high SMAD3 expression had significantly lower median OS than did patients with SMAD3 underexpression (290 vs. 531 days). Importantly, further analysis using a Cox proportional hazard regression model revealed that SMAD3 expression was an independent prognostic factor predicting poorer survival in PDAC patients. Analysis of _SMAD3_ mRNA levels from the TCGA cohort confirmed these results. Similar findings regarding OS have been presented by [PERSON] et al. [49]. Moreover, they demonstrated that the expression of SMAD3 in PDAC correlated with malignant characteristics, including EMT-like features and lymph node metastasis. This is in partial agreement with our study since we observed a significant correlation of _SMAD3_ mRNA but not protein expression with the features of aggressive tumor behavior, such as higher grade, positive nodal status, higher pT category and TNM stage. These results confirm that SMAD3 expression may reflect the malignancy potential of PDAC and serve as a biomarker of a poor prognosis. [PERSON]'s analysis showed strong positive correlations between _SMAD3_ and _EZR_ in the TCGA cohort. Recently, various studies demonstrated that Erzin may play an important role in cancer progression, while its overexpression correlates with patient survival and various clinicopathological parameters [50; 51; 52]. According to our report, Erzin expression was elevated in PDAC samples compared to adjacent tissues, which is consistent with the studies by other researchers [50; 52; 53]. Immunohistochemistryidochemical analysis of our cohort showed that Erzin protein expression did not correlate with clinicopathological parameters. However, _EZR_ mRNA expression significantly correlated with aggressive phenotypes of PDACs from the TCGA cohort, including differentiation stage, pT status and TNM stage. Previous studies have shown elevated Erzin protein expression correlated with tumor size, clinical stage and positive lymph node metastasis in PDAC [50]. Our Kaplan-Meier survival analysis demonstrated that high Erzin expression correlated with a shorter OS rate than a low expression (118 vs. 450 days). Moreover, we revealed that elevated Erzin expression in our cohort was an independent prognostic factor predicting poorer survival in PDAC patients. The effects of _EZR_ expression on the survival of patients from our cohort and TCGA cohort are consistent.