Phenylbutyrate—a pan-HDAC inhibitor—suppresses proliferation of glioblastoma LN-229 cell line

Abstract

Phenylbutyrate (PBA) is a histone deacetylase inhibitor known for inducing differentiation, cell cycle arrest, and apoptosis in various cancer cells. However, the effects of PBA seem to be very cell-type-specific and sometimes limited exclusively to a particular cell line. Here, we provided novel information concerning cellular effects of PBA in LN-229 and LN-18 glioblastoma cell lines which have not been previously evaluated in context of PBA exposure. We found that LN-18 cells were PBA-insensitive even at high concentrations of PBA. In contrary, in LN-229 cells, 5 and 15 mmol/L PBA inhibited cell growth and proliferation mainly by causing prominent changes in cell morphology and promoting S- and G2/M-dependent cell cycle arrest. Moreover, we observed nearly a 3-fold increase in apoptosis of LN-229 cells treated with 15 mmol/L PBA, in comparison to control. Furthermore, PBA was found to up-regulate the expression of p21 whereas p53 expression level remained unchanged. We also showed that PBA down-regulated the expression of the anti-apoptotic genes Bcl-2/Bcl-X L, however without affecting the expression of pro-apoptotic Bax and Bim. Taken together, our results suggest that PBA might potentially be considered as an agent slowing-down the progress of glioblastoma; however, further analyses are still needed to comprehensively resolve the nature of its activity in this type of cancer.

An update on the use of benzoate, phenylacetate and phenylbutyrate ammonia scavengers for interrogating and modifying liver nitrogen metabolism and its implications in urea cycle disorders and liver disease

“…An a posteriori study concluded that the pharmacokinetics and pharmacodynamics of PB in glioblastoma patients is affected by concomitant administration of P450-inducing anticonvulsants [52], it being plausible that the limited concentrations of PB achievable in the cells in vivo partly explain the lack of efficiency shown in the earlier clinical trials. In agreement with this, a very recent study has assessed PB-treatment in different glioblastoma cell lines, concluding that the effects of PB seem to be cell-type-specific in a dose-dependent manner [56]. …”

Silica nanoparticle-induced oxidative stress and mitochondrial damage is followed by activation of intrinsic apoptosis pathway in glioblastoma cells

“…Primer sequences for DDIT3 (CHOP), BAX, BCL2L11 (BIM), BCL2, BCL2L1 (BCL-X L ), PUMA, NOXA, and housekeeping RPL13A have been described in our previous work. 15,16 Sequences of the other PCR primers were previously described as: HSPA5 (GRP78), 22 SOD1, 23 SOD2, 23 CAT, 23 COX2, 24 and IL1B. 24 Additional evaluation of primer accuracy was done using Primer-BLAST software.…”

“…A number of other factors, such as molecular heterogeneity, anaplastic cancer cells, and difficulties in targeting therapeutics specifically to transformed cells, are among the limitations halting development of effective glioblastoma therapies. [15][16][17] To address this need for new therapeutic strategies, the field of nanomedicine is currently being explored in the management of brain malignancies. 17 To date, several reports illustrating the utility of SiNPs for brain-tumor treatment have been published.…”

PBA Preferentially Impairs Cell Survival of Glioblastomas Carrying mutp53 by Reducing Its Expression Level, Stabilizing wtp53, Downregulating the Mevalonate Kinase and Dysregulating UPR

“…Moreover, the chaperoning activity of PBA may influence the ER stress/UPR activation, orchestrated by IRE1alpha (inositol-requiring enzyme 1 alpha), PERK (PKR-like endoplasmic reticulum kinase) and ATF6 (Cyclic AMP-dependent transcription factor ATF-6 alpha), which regulate the balance between cell survival and cell death, mainly based on the expression of BIP (Binding Immunoglobulin Protein) and CHOP (C/EBP Homologous Protein), respectively. Although PBA has been reported to induce apoptosis in the glioma cell line LN-2299 by downregulating the anti-apoptotic bcl2 family proteins [12] the underlying mechanisms have not been investigated. In this study, the impact of PBA treatment on mutant and wtp53 expression, on the mevalonate pathway and ER stress/UPR was addressed as possible mechanisms of cell death induction in U373, T98 and U87, glioblastoma cell lines harboring mutant and wtp53, respectively.…”