TGF-Β1/SMAD2 AND HIPPO/YAP SIGNALLING PATHWAYS AS KEY FACTORS OF CHEMORESISTANCE IN RECURRENT GLIOBLASTOMA CELLS

Vol 1, 2020 - 131224
DR - Doctoral Student
Favorite this paper
How to cite this paper?
Abstract

INTRODUCTION AND OBJECTIVES: Glioblastoma is the most lethal brain
tumor. Its poor prognosis is due to chemotherapy-resistant tumor cells that serve
as the source of new tumor cells, leading to resurgence of the tumor with a more
aggressive phenotype. Several signaling pathways are involved in the control of
cell proliferation and migration. One of the altered pathways is TGF-β1/SMAD2
which controls proliferation and tumor migration. Cooperation between the
SMAD2/3 and Hippo/YAP pathways has been described to control a regulatory
complex that changes functions between pluripotency maintenance and cell
differentiation. A proposed mechanism is that nuclear YAP is responsible for the
switch of TGF-β1 function through the action of a transcription machinery
composed by members of both pathways, and that this new transcriptional
program results in the expression of some genes, among them
Connective Tissue Growth Factor (CTGF), which is a malignant and
chemoresistant factor in tumors. Our objective is to study the molecular
mechanisms of the transcriptional complex formed by SMAD2/3 and YAP and
their influence on chemoresistance. MATHERIALS AND METHODS: In our
study, a human lineage of Glioblastoma, GBM11, recurrent after treatment with
Temozolomide, first-line therapy for Glioblastoma treatment, was used. To further
disclose the molecular mechanism of CTGF transcription, we established three
new GBM11 lineages, with depletions made from CRISPR-Cas9, for genes of
interest: GBM11 SMAD2-/-, GBM11 YAP-/-, GBM11 CTGF-/-. RESULTS AND
CONCLUSION: Real-time PCR indicated that CTGF has higher expression in
GBM11 cells when compared to primary Glioblastoma cells, that have not
undergone chemotherapeutic treatment. Immunofluorescence showed that both
proteins, YAP and SMAD2, have nuclear and cytoplasmic location. RT-qPCR
also showed that CTGF expression is lower in the GBM11 SMAD2- / - line, and
that the basal CTGF expression is rescued when treated with TGF-β1. Western
Blotting analysis showed that GBM11 SMAD2-/- has ERK MAPK signaling
pathway downregulated while in GBM11 YAP-/- ERK MAPK pathway is
overexpressed. Besides that, GBM11 SMAD2-/- cell line is the most sensitive to
treatment with Temozolomide, where 65% of the population dies. However, GBM
11 YAP-/- is less sensitive to the Temozolomide. Treatment of GBM11 YAP-/- with
specific inhibitors of TGF- β1 and MAPK pathways sensitives the cells to
chemotherapy. Our data indicate that CTGF expression may be involved in the
degree of tumor malignancy and chemoresistance, in addition to being apparently
dependent primarily on the TGF-β1 signaling pathway. Furthermore, activation of
the ERK MAPK pathway appears to be critical to the chemoresistance of these
cells.

Share your ideas or questions with the authors!

Did you know that the greatest stimulus in scientific and cultural development is curiosity? Leave your questions or suggestions to the author!

Sign in to interact

Have a question or suggestion? Share your feedback with the authors!

Institutions
  • 1 Universidade Federal do Rio de Janeiro
  • 2 Laboratório de Biologia das Células Gliais / Instituto de Ciências Biomédicas / Universidade Federal do Rio de Janeiro
  • 3 Instituto Estadual do Cérebro Paulo Niemeyer
Track
  • Cell Signaling
Keywords
YAP
TGF- β1
Chemoresistance
Glioblastoma
CRISPR-Cas9