Abstract Title

EFFECT OF 4-HYDROXYNONENAL ON MIGRATION AND INVASION ENHANCER PROTEIN 1 (MIEN1) IN COLORECTAL CANCER

Presenter Name

Urmimala Raychaudhuri

Abstract

MIEN1 could be a potential target for therapy in colorectal cancer.

Presentation Type

Poster

Purpose (a):

Colorectal cancer (CRC) is the second leading cause of death in the United States. It is believed that the intestinal mucosa is constantly challenged with diet- and bacterial-derived oxidants and carcinogens. Chronic exposure of such challenging conditions may lead to the generation of reactive oxygen species (ROS). ROS initiate an autocatalytic chain of lipid peroxidation (LPO) of polyunsaturated fatty acids, resulting in the formation of large amounts of toxic electrophilic species and free radicals that may play important roles in various human diseases, including carcinogenesis. Consequently, even a minimal transient exposure of cells to ROS causes substantial lipid peroxidation, leading to a significant rise in the level of LPO end product, 4-hydroxynonenal (4-HNE), which is considered to be one of the most abundant cytotoxic aldehydes. HNE reacts not only with DNA but also with proteins and other molecules containing thiol and other nucleophilic groups and can alter the protein structure and functions.

We have identified a novel protein called Migration and Invasion Enhancer protein 1 (MIEN1), is highly overexpressed in cancer cells and modulates the AKT activity as a membrane bound adaptor protein. Ectopic expression of MIEN1 activates Akt mediated downstream signaling through NF-kB pathway and induces the expression of several migratory and invasive proteins. However, 4-HNE has also been reported to induce the expression of various proteins involved in cell proliferation and migration. We hypothesize that 4-HNE mediated oxidative stress plays an important role in the etiology of colorectal cancer by modulating the expression and function of MIEN1. In the present studies, we have addressed this question by investigating the effect of 4-HNE on MIEN1 expression in colorectal cancer cell lines SW480 and HT29.

Methods (b):

Colorectal cancer cell lines, SW480 and HT29 were grown in RPMI-1640 medium containing 10% fetal bovine serum, in a humidified incubator at 37°C with 5% CO2. The toxicity of 4HNE in SW480 cells was determined by MTT assay. The effect of 4HNE on MIEN1 expression was determined by Western blotting in HT29. The effect of 4HNE on SW480 cell migration was examined by scratch wound assay. The LigandFit docking program available in the Accelrys molecular modeling software – Discovery studio, was used to carry out a docking study for the protein MIEN1 and substrate 4HNE. The 3D structure of the protein was obtained from PDB.

Results (c):

Our results demonstrated that exposure of 4HNE to SW480 cells is toxic. 4HNE concentrations ranging from 0 to 250 μM gradually decreased cell viability in SW480 cells corresponding to an IC50 value of 160 μM. Furthermore, our Western blot analysis demonstrated that treatment of 4HNE increased the expression of MIEN1 at the protein level in HT-29 cells. The scratch wound healing assay showed an increase in migration after treatment with low doses of 4HNE. The docking study produced 10 top scoring(dock score) poses. The poses indicate a possible interaction between the protein binding sites and the substrate (4HNE) including formation of hydrogen bonds between them.

Conclusions (d):

Together, these results suggest that 4HNE induced cell migration could be mediated via MIEN1.

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EFFECT OF 4-HYDROXYNONENAL ON MIGRATION AND INVASION ENHANCER PROTEIN 1 (MIEN1) IN COLORECTAL CANCER

MIEN1 could be a potential target for therapy in colorectal cancer.