Abstract 1878: Inhibition of the Transforming Growth Factor beta pathway in human glioblastoma cell lines induces apoptosis and inhibits anoikis escape

Abstract

Glioblastoma Multiforme (GBM) is the most prevalent malignant brain tumor accounting for 60-70% of all gliomas. Current achieved median patient survival ranges only 12-15 months, and improvements in survival over the last century can be measured only in weeks. A hallmark of this malignancy is the intrinsic resistance to current therapies. The Transforming Growth Factor beta (TGF-beta) signaling pathway plays a key role in GBM. Several inhibitors of different elements and regulators of the TGF-beta pathway have entered to clinical trials.

Here, we analyzed the potential effect of P144, a TGF-beta pathway inhibitor peptide, over cell proliferation and apoptosis in commercial GBM cell lines (A172 and U-87 MG). We found that treatment with P144 significantly decreased cell proliferation of both cell lines analyzed. In addition, different apoptosis determinations such as ELISA and Acridine Orange/Ethidium Bromide (AO/EB) staining, confirmed a significant increase in apoptosis in both cell lines.

Quantification of SMAD2 phosphorylation status and its nuclear translocation, by western blot, confirmed the inhibition of TGF-beta signaling by P144. These data support the correlation between TGF-beta pathway inhibition and the apoptotic process induction.

Anoikis escape sustains invasiveness and metastatic potential in GBM, and has been established as a clear target against tumor progression. Due to P144 clear effect on apoptosis, we analyzed its influence on anoikis escape. The inhibition of anoikis escape by P144 was confirmed in A172 and U-87 MG cell lines under in vitro anchorage-independent culture conditions. The significant upregulation of BAX, Lamin A and Lamin C produced by P144 confirmed the induction of this apoptotic subtype process in the analyzed cell lines.

We can conclude that P144 increases apoptosis and induces anoikis through inhibition of the TGF-beta signaling pathway. Our results highlight the therapeutic potential of P144 for the treatment against GBM. However, previous to further clinical development, additional studies are required in order to confirm the effect of P144 over GBM in the brain environment, as well as to explore the therapeutic potential of P144 in combination with current and emerging molecular based therapies.

Citation Format: Gabriel Gallo-Oller, Javier Dotor, Xing Fan, Javier S. Castresana. Inhibition of the Transforming Growth Factor beta pathway in human glioblastoma cell lines induces apoptosis and inhibits anoikis escape. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1878.