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Identification and Characterization of Metastatic Factors by Gene Transfer into the Novel RIP-Tag; RIP-tva Murine Model
Published on: October 16, 2017
Comparative transcriptome and proteome analysis of Ha-ras and B-raf mutated mouse liver tumors
Benjamin Rignall1, Carina Ittrich, Eberhard Krause
1Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Tubingen, Germany.
Abstract:
Mouse liver tumors frequently harbor activating mutations in the Ha-ras protooncogene. In addition, mutations are also found in the B-raf gene leading to constitutive activation of the B-Raf kinase. In two previous studies, we have investigated by microarray analysis the effect of the mutations on the mRNA expression patterns of the respective tumors. In the present study, we analyzed proteome changes in Ha-ras and B-raf mutated liver tumors by 2-D gel-electrophoretic separation of proteins followed by their identification by mass spectrometry. In total, 104 significantly altered protein spots were identified in Ha-ras mutated tumors and 111 in B-raf mutated tumors when compared to the corresponding normal liver tissue. The changes in protein expression patterns were highly correlated between Ha-ras and B-raf mutated tumors, and in the majority of the cases, both tumor types showed the respective alteration. Most of the tumor-specific changes in protein expression were reflected by similar changes in their mRNAs except for some up-regulated proteins without accompanying changes in mRNA levels. Interestingly, Ha-ras but not B-raf mutated tumors showed high levels of the phosphorylated (activated) form of the Ras/Raf/MEK effector kinase ERK which was, however, not associated with any detectable difference in the transcriptome or protein setup of the tumors.
Insights
Activating mutations in Ha-ras and B-raf genes drive mouse liver tumors. Proteomic analysis revealed significant protein changes, largely mirroring mRNA alterations, with unique ERK pathway activation in Ha-ras tumors.
Area of Science:
- Oncology
- Molecular Biology
- Proteomics
Background:
- Mouse liver tumors often exhibit activating mutations in Ha-ras and B-raf genes.
- Previous studies utilized microarray analysis to assess mRNA expression changes in these tumors.
Purpose of the Study:
- To analyze proteome alterations in Ha-ras and B-raf mutated mouse liver tumors.
- To compare proteomic findings with existing transcriptomic data.
Main Methods:
- Two-dimensional gel electrophoresis (2-D PAGE) for protein separation.
- Mass spectrometry for protein identification.
- Comparison of tumor proteomes with normal liver tissue.
Main Results:
- 104 and 111 significantly altered protein spots identified in Ha-ras and B-raf mutated tumors, respectively.
- Protein expression changes were highly correlated between Ha-ras and B-raf mutated tumors.
- Most proteomic changes were reflected in mRNA levels, with exceptions of up-regulated proteins lacking mRNA alteration.
- Ha-ras mutated tumors showed elevated phosphorylated ERK, without corresponding transcriptome or proteome differences.
Conclusions:
- Proteomic analysis provides a deeper understanding of molecular changes in Ha-ras and B-raf driven liver tumors.
- Discrepancies between mRNA and protein levels highlight post-transcriptional regulatory mechanisms.
- Specific activation of ERK in Ha-ras tumors warrants further investigation despite lack of broad transcriptomic/proteomic impact.
