Estudio de la regulación de la expresión de HES1 y su modulación por 2OHOA en glioma

Abstract

Gliomas are the most common and aggressive cancer tumours of the central nervous system, being the life expectancy of patients very low even after treatment with de standard of care (SoC). The membrane lipid therapy is based on the regulation of the membrane’s structure and organization with the consequent modulation of certain cell signals. In this context, 2-hydroxioleic acid (2OHOA) was developed, which has successfully finished a phase I/IIa in patients with glioma and other advanced solid tumours. In addition, in a xenograft model of human GBM, it provided a greater anti-tumour effect and absence of relapse compared to TMZ, the current SoC against this pathology. Due to the implication of HES1 in tumorigenesis and cell survival, the aim of this study was to study the relevance of HES1 expression in the 2OHOA mechanism of action on cell viability, as well as identifying the signaling pathways involved. The results showed that its expression was relevant in the 2OHOA effect on cell viability. In addition, the positive correlation between HES1 mRNA levels in response to treatment and the IC50 of several glioma cell lines and between its expression and tumour volume in vivo assays, propose this gene as a possible target for the treatment of GBM. 2OHOA was able to prevent the induction of HES1 expression through multiple pathways except when Wnt/β-catenin pathway was activated by silencing GSK3αβ, proposing that alpha isoform could be relevant for the 2OHOA effect on the HES1 expression. In addition, 2OHOA negatively modulated the Notch pathway at multiple levels of the signal transduction: preventing the receptor processing, the translocation of NICD to the nucleus, the transcription of its target genes and those related to its activation, even in the presence of exogenous activators, also preventing its recovery. 2OHOA was also able to inhibit the Wnt/β-catenin pathway, repressing the expression of TCF/LEF dependent genes and related genes to this pathway, decreasing the total levels and translocation of β-catenina to the nucleus. It was also determined that the expression of one of the target genes, AXIN2, was relevant in the function that 2OHOA exerts on cell viability. The study of the interaction between both pathways showed a negative modulation between them, inhibiting the transcription of TCF/LEF- dependent genes in NICD3 overexpression and breaking down β-catenin in Notch inhibition. In contrast, Wnt/β-catenin showed that GSK3β could be relevant to decreasing NICD levels. In the light of these results, it can be concluded that 2OHOA exerts its anti-tumour activity through the inhibition of the Notch pathway, the repression of HES1 expression and the modulation of other pathways preventing the recovery of the mRNA levels of this gene, being effective against this pathology.