Proteomic and phosphoproteomic profiling of a TRIB2-KO glioblastoma-derived cell line reveals new roles in cell signaling

Glioblastoma, a type of cancer of the brain or the spinal cord, forms from astrocytes supporting nerve cells. Despite the various treatments available, the prognosis for glioblastoma is poor, with a median survival time of about 14 months. Tribble proteins, or Tribbles, are pseudokinases with very important roles in cell signaling regulation. These proteins present at least a pseudokinase domain and a C-terminal domain, by which they act as scaffold for a diverse range of proteins to regulate their post-translational modifications and their cellular location. They primarily signal via noncatalytic mechanisms, such as protein-protein interactions, contributing to the development of various human diseases. Trib2 has been shown to interact specifically with E3-ubiquitin ligases and MAP kinases through its C-terminal domain, and with their substrates via the C-terminal domain and the pseudokinase domain. Thus, TRIB2 acts as a regulator of important cellular pathways such as PI3K-Akt, NFkB, or Wnt, all of them related to cell survival and proliferation. These pathways are key in the development and progression of many types of cancer, including glioblastoma.

Here, we have analyzed the proteome and phosphoproteome of the highly-TRIB2-expressing glioblastoma-derived cell line Lnn229, and of two different Crispr-Cas9-generated TRIB2-KO clones. SILAC and label-free quantitative proteomics analyses have been performed using data-independent acquisition with an Orbitrap Astral Mass Spectrometer to address the interactome and phosphoproteome associated to this pseudokinase. Our data shows that TRIB2 regulates the phosphorylation and expression levels of important cellular proteins, which play a key role in survival, metastasis, and proliferation. Results suggest that the modulation of the pathways where Trib2 is involved could help in the management of glioblastoma and other cancers, where these pathways are dysregulated.