Background. The altered regulation of Wnt/β-Catenin pathways is linked with colorectal (CRC) carcinogenesis. Recent studies have shown that the Wnt/β-Catenin pathways are activated by reactive oxygen species (ROS) production, but the underlying molecular mechanisms are still unknown. Increased ROS are responsible for chronic inflammation, DNA lesions and repair systems. In order to evaluate the relationship among oxidative stress and canonical/non-canonical Wnt pathways, we studied the response to enhanced ROS in colorectal cancer cell lines with different Wnt signalling behaviour. Methods. HCT116 (MSI) and SW480 (MSS) cells were treated with H2O2 at different concentrations and times. Cell viability was determined by MTS and measured by the GloMax-Multi Detection System. Gene expression was evaluated by SYBR Green quantitative real-time PCR. Statistical analysis was performed by T-test (p value<0.05). Results. MTS showed different inhibition rates of cell proliferation at H2O2 concentrations. Acute stress was induced using H2O2 [2 mM and 10 mM] for 15’, 30’. H2O2 [2mM] treatment induced up-regulation of expression of canonical/non canonical molecules (LRP6 and LEF1; ROR2 and JUN/AP1) in SW480, and reduced expression of ROR2 and LRP6 co-receptors in HCT116. In SW480, at H2O2 [10mM], both ways showed a dose dependent increase. In HCT116, APC, LRP6, LEF1, P65-NFkB down-regulated gene expression was dependent on treatment time, in opposition to non-canonical ROR2 receptor. MUTYH, OGG1, NRF2, COX2 and JUN/AP1 showed significant increased expression. Conclusions. In MSI and MSS colon cancer cells, oxidative stress differently affects the WNT pathways. Our results could devise a new scenario for CRC therapeutic approaches.
T Catalano;S Loddo;G Ferlazzo
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