Supervisors info:
Αγγελική Σαέττα, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Αφροδίτη Νόννη, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Χαρά Γακιοπούλου, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Summary:
Introduction: Wnt signaling pathway plays an important role in embryonic development and adult tissue homeostasis. Alterations in Wnt pathway components’ expression can lead to dysregulation of Wnt signaling which is implicated in the pathogenesis of colorectal cancer. Dysregulation of Wnt signaling pathway is a common feature in colorectal carcinogenesis which makes it an appealing therapeutic target.
Materials and Methods: Total RNA was isolated from 102 colorectal tumors and 10 normal adjacent tissues, which was reverse transcribed to cDNA. The relative mRNA expression levels of WNT2, Frizzled 4 (FZD4), Frizzled 7 (FZD7), β-catenin (CTNNB1), TCF4 and LEF1 were determined by semi-quantitative Real Time PCR, with PPIA as reference gene. Data were analyzed using the comparative ΔΔCt method. Statistical analysis was performed with software SPSS v24 for Windows, in search for possible correlation between the expression levels of the investigated genes and clinicopathological features, as well as with the presence of mutations in KRAS, NRAS and BRAF genes of the MAPK pathway.
Results: Increased relative mRNA expression levels of WNT2, FZD4, FZD7, TCF4 and LEF1 genes were found in 59%, 39%, 53%, 47% and 48% of colorectal carcinomas, while β-catenin showed decreased expression levels in 57% of our samples. Interestingly, mRNA levels of TCF4 and LEF1 were associated with T category, showing increased expression levels in Τ3/4 colorectal tumors. Also, β-catenin expression levels where statistically associated with metastasis in regional lymph nodes (N), as decreased levels where seen in N2 tumors. No statistically significant correlation was observed between the expression levels of the investigated genes and the presence of mutations in MAPK genes. Finally, statistically significant positive linear correlation was observed among the expression levels of all the investigated genes, with strong correlation between β-catenin, TCF4 and LEF1 and marginally strong between WNT2 ligand and the FZD4 and FZD7 receptors and also between FZD4 and the TCF4/LEF1 transcription factors.
Discussion: We observed dysregulation of the mRNA expression levels of the investigated genes in a significant percentage of our cohort. This observation along with the correlation of the expression levels among the investigated genes reflects the dysregulation of the Wnt pathway in multiple levels as well as its importance for colorectal carcinogenesis. The correlation of β-catenin, TCF4 and LEF1 expression levels with TNM stage indicates their importance as possible biomarkers of tumor aggressiveness in colorectal cancer. Further studies of Wnt pathway genes’ expression levels could provide new targets for the treatment of colorectal cancer.
