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Direct integrin alphavbeta6-ERK binding: implications for tumour growth
Nuzhat Ahmed1, Jun Niu, Douglas J Dorahy
1Gynaecological Cancer Research Centre, The Royal Women's Hospital, Melbourne and University of Melbourne, Melbourne, Australia.
Abstract:
Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer in vivo. Here we demonstrate a direct link between the extracellular signal-regulated kinase ERK2 and the growth-promoting cell adhesion molecule, integrin alphavbeta6, in colon cancer cells. Down-regulation of beta6 integrin subunit expression inhibits tumour growth in vivo and MAP kinase activity in response to serum stimulation. In alphavbeta6-expressing cells ERK2 is bound only to the beta6 subunit. The increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation is all accounted for by beta6-bound ERK. Deletion of the ERK2 binding site on the beta6 cytoplasmic domain inhibits tumour growth and leads to an association between ERK and the beta5 subunit. The physical interaction between integrin alphavbeta6 and ERK2 defines a novel paradigm of integrin-mediated signalling and provides a therapeutic target for cancer treatment.
Insights
Blocking the mitogen-activated protein (MAP) kinase pathway and integrin alphavbeta6 inhibits colon cancer growth. This study reveals a direct link between ERK2 and integrin alphavbeta6, offering a new therapeutic target for colon cancer.
Area of Science:
- Oncology
- Molecular Biology
- Cell Signaling
Background:
- The mitogen-activated protein (MAP) kinase pathway is crucial for cell growth and is often dysregulated in cancer.
- Integrins are cell adhesion molecules that play roles in cell signaling and cancer progression.
- Integrin alphavbeta6 is implicated in promoting tumor growth in various cancers, including colon cancer.
Purpose of the Study:
- To investigate the direct link between ERK2, a key component of the MAP kinase pathway, and the integrin alphavbeta6 in colon cancer cells.
- To determine the functional significance of the interaction between ERK2 and integrin alphavbeta6 in colon cancer growth.
- To explore the potential of targeting this interaction as a therapeutic strategy for colon cancer.
Main Methods:
- Utilized colon cancer cell lines with varying expression levels of integrin alphavbeta6.
- Employed co-immunoprecipitation assays to detect physical interactions between ERK2 and integrin subunits.
- Performed in vivo tumor growth studies in mouse models to assess the impact of modulating the integrin-ERK2 interaction.
- Conducted experiments involving deletion of the ERK2 binding site on the beta6 cytoplasmic domain.
Main Results:
- Demonstrated a direct physical association between ERK2 and the beta6 integrin subunit in alphavbeta6-expressing colon cancer cells.
- Showed that down-regulation of beta6 integrin subunit expression inhibits tumor growth in vivo and reduces MAP kinase activity.
- Found that deletion of the ERK2 binding site on the beta6 cytoplasmic domain inhibits tumor growth and alters ERK subunit association.
- Established that ERK2 bound to beta6 accounts for the increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation.
Conclusions:
- The physical interaction between integrin alphavbeta6 and ERK2 represents a novel mechanism of integrin-mediated signaling in colon cancer.
- Targeting the alphavbeta6-ERK2 interaction can suppress colon cancer growth, highlighting its potential as a therapeutic target.
- This discovery provides a new paradigm for understanding integrin function in cancer and opens avenues for drug development.