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Alternative microexon splicing by RBFOX2 and PTBP1 is associated with metastasis in colorectal cancer
Yasushi Mochizuki1,2, Ryo Funayama1, Matsuyuki Shirota3
1Department of Cell Proliferation, ART, Graduate School of Medicine, Tohoku University, Sendai, Japan.
Abstract:
The splicing of microexons (very small exons) is frequently dysregulated in the brain of individuals with autism spectrum disorder. However, little is known of the patterns, regulatory mechanisms and roles of microexon splicing in cancer. We here examined the transcriptome-wide profile of microexon splicing in matched colorectal cancer (CRC) and normal tissue specimens. Out of 1492 microexons comprising 3 to 15 nucleotides, 21 (1%) manifested differential splicing between CRC and normal tissue. The 21 genes harboring the differentially spliced microexons were enriched in gene ontology terms related to cell adhesion and migration. RNA interference-mediated knockdown experiments identified two splicing factors, RBFOX2 and PTBP1, as regulators of microexon splicing in CRC cells. RBFOX2 and PTBP1 were found to directly bind to microexon-containing pre-mRNAs and to control their splicing in such cells. Differential microexon splicing was shown to be due, at least in part, to altered expression of RBFOX2 and PTBP1 in CRC tissue compared to matched normal tissue. Finally, we found that changes in the pattern of microexon splicing were associated with CRC metastasis. Our data thus suggest that altered expression of RBFOX2 and PTBP1 might influence CRC metastasis through the regulation of microexon splicing.
Insights
Microexon splicing alterations in colorectal cancer (CRC) are linked to cell adhesion and migration. Dysregulated splicing factors RBFOX2 and PTBP1 influence CRC metastasis.
Area of Science:
- Molecular Biology
- Genomics
- Cancer Research
Background:
- Microexon splicing dysregulation is observed in autism spectrum disorder.
- The role of microexon splicing in cancer, particularly colorectal cancer (CRC), remains largely unexplored.
Purpose of the Study:
- To investigate microexon splicing patterns in colorectal cancer (CRC).
- To identify regulatory mechanisms and potential roles of microexon splicing in CRC progression and metastasis.
Main Methods:
- Transcriptome-wide analysis of microexon splicing in matched CRC and normal tissues.
- RNA interference-mediated knockdown of splicing factors RBFOX2 and PTBP1 in CRC cells.
- Analysis of splicing factor binding and expression levels in CRC tissues.
Main Results:
- 21 out of 1492 microexons showed differential splicing between CRC and normal tissues.
- Genes with altered microexons were associated with cell adhesion and migration.
- RBFOX2 and PTBP1 were identified as key regulators of microexon splicing in CRC cells, directly binding to pre-mRNAs.
- Altered expression of RBFOX2 and PTBP1 correlated with differential microexon splicing in CRC.
- Microexon splicing changes were associated with CRC metastasis.
Conclusions:
- Altered expression of splicing factors RBFOX2 and PTBP1 contributes to differential microexon splicing in CRC.
- Microexon splicing dysregulation, driven by RBFOX2 and PTBP1, may play a role in colorectal cancer metastasis.