Altogether, these observations suggest that HDAC4 and HDAC6 are guardians of irradiation-induced DNA damages and stemness, thus promoting radioresistance, and may represent potential prognostic markers and therapeutic targets in GBM.
Finally, HDAC6 inhibition decreased the expression of mesenchymal markers, contributing to reverse epithelial‑mesenchymal transition in glioblastoma cells.
Methylation of the HDAC4, HDAC5 and HDAC6 genes was assessed in 29 tumor samples (astrocytomas grades I, III, and IV) and in the glioblastoma cell lines U87, U251, U343, SF188, and T98G by methylation-specific quantitative PCR (MSED-qPCR).
Our preliminary results suggest that both HDAC4 and HDAC6 together with the TGF-β/Smad pathway may be involved in progression of GBM and this cross talking could be a useful prognostic marker in this deadly disease.
Thus, our data demonstrate a previously unrecognized regulation pathway in that HDAC6 increases GBM growth through attenuating transforming growth factor β (TGFβ) receptor signaling.
Additionally, the results of immunohistochemistry showed that TDP-43 and HDAC6 collaborated in GBM-tumor lesions and negatively correlated with the relapse-free survival of GBM patients.