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Mutational inactivation of transforming growth factor beta receptor type II in microsatellite stable colon cancers
W M Grady1, L L Myeroff, S E Swinler
1Department of Medicine, Ireland Cancer Center, Case Western Reserve University and University Hospitals of Cleveland, Ohio 44106, USA.
Abstract:
We previously demonstrated that mutational inactivation of transforming growth factor beta type II receptors (RIIs) is very common among the 13% of human colon cancers with microsatellite instability. These mutations principally cluster in the BAT-RII polyadenine sequence repeat. Among microsatellite stable (MSS) colon cancers, we now find that non-BAT-RII point mutations inactivate RII in another 15% of cases, thus doubling the known number of colon cancers in which RII mutations are pathogenetic. Functional analysis confirms that these mutations inactivate RII signaling. Moreover, another 55% of MSS colon cancers demonstrate a transforming growth factor beta signaling blockade distal to RII. The transforming growth factor beta pathway and RII in particular are major targets for inactivation in MSS colon cancers as well as in colon cancers with microsatellite instability.
Insights
Transforming growth factor beta type II receptors (RIIs) are frequently inactivated in colon cancer. New findings reveal RII mutations and signaling blockades in microsatellite-stable tumors, highlighting RII as a key target.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Transforming growth factor beta type II receptors (RIIs) are crucial in cell growth regulation.
- Mutational inactivation of RII is common in microsatellite unstable (MSI) colon cancers, particularly in the BAT-RII sequence.
- Understanding RII alterations in microsatellite stable (MSS) colon cancers is critical for comprehensive cancer pathway analysis.
Purpose of the Study:
- To investigate the role of RII mutations in MSS colon cancers.
- To identify alternative mechanisms of transforming growth factor beta (TGF-β) pathway inactivation distal to RII in MSS colon cancers.
- To assess the overall significance of RII and TGF-β pathway alterations in both MSI and MSS colon cancer subtypes.
Main Methods:
- Analysis of RII mutations in a cohort of MSS colon cancers.
- Functional assays to confirm the impact of identified mutations on RII signaling.
- Investigation of TGF-β pathway components downstream of RII in MSS tumors.
Main Results:
- Non-BAT-RII point mutations were found to inactivate RII in 15% of MSS colon cancers.
- Functional analysis confirmed that these novel mutations lead to RII signaling inactivation.
- A transforming growth factor beta signaling blockade distal to RII was identified in an additional 55% of MSS colon cancers.
Conclusions:
- RII mutations are a significant pathogenetic factor in a substantial proportion of MSS colon cancers.
- The transforming growth factor beta pathway, particularly RII, is a major target for inactivation across both MSI and MSS colon cancer types.
- These findings expand the known mechanisms of RII inactivation and TGF-β pathway dysregulation in colon carcinogenesis.