Cytosolic EpCAM cooperates with H-Ras to regulate epithelial to mesenchymal transition through ZEB1

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• Activating Ras oncogene mutations are central to oncogenesis.
• Ras-driven tumorigenesis upregulates genes and signaling cascades, transforming normal cells.
• Altered localization of epithelial cell adhesion molecule (EpCAM) in Ras-expressing cells was investigated.

Purpose of the Study:

• To investigate the role of altered EpCAM localization in Ras-expressing cells.
• To determine if EpCAM mutations cooperate with H-Ras to promote cancer progression.
• To identify potential therapeutic strategies for cancers with EpCAM and Ras mutations.

Main Methods:

• Microarray analysis to assess EpCAM expression in Ras-expressing cells.
• Fluorescent and confocal microscopy to observe EpCAM localization and cellular morphology.
• Generation of a cancer-associated EpCAM mutant (EpCAM-L240A) retained in the cytosol.
• Transduction of normal MCF-10A cells with H-Ras and either WT EpCAM or EpCAM-L240A.
• Treatment with MEK/JNK inhibitors, paclitaxel, and quercetin to assess therapeutic responses.

Main Results:

• Ras expression induced EpCAM expression in normal breast epithelial cells.
• H-Ras mediated transformation promoted epithelial-to-mesenchymal transition (EMT) with EpCAM.
• EpCAM-L240A markedly altered cells, promoting a mesenchymal phenotype and EMT factors (FRA1, ZEB1), and inflammatory cytokines (IL-6, IL-8, IL1).
• Altered morphology was reversed by MEK inhibitors and partially by JNK inhibition.
• Transformed cells were sensitized to apoptosis by paclitaxel and quercetin.

Conclusions:

• EpCAM mutations cooperate with H-Ras to promote EMT.
• Altered EpCAM localization plays a significant role in Ras-driven tumorigenesis.
• Targeting EpCAM and Ras pathways presents future therapeutic opportunities in cancer treatment.