Down regulation of human telomerase reverse transcriptase (hTERT) expression by BIBR1532 in human glioblastoma LN18 cells

Abstract

Increased telomerase activity can be blocked by targeting the hTERT activity at both RNA and catalytic subunits. Various inhibitors had been used to regulate hTERT activity in glioblastoma cell lines and showed promising results. The present study hypothesized that the telomerase specific inhibitor BIBR1532 can effectively down-regulate the telomerase activity in LN18 glioblastoma cell line. LN18 glioblastoma cell line was treated with various concentrations of BIBR1532 at different time intervals. MTT assay was performed to determine cell viability after BIBR1532 treatment. hTERT mRNA and protein expression were determined by qRT-PCR and western blotting, respectively. Flow cytometry and TRAP assay was performed to detect the rate of apoptosis and telomerase activity in treated and control samples. One-way ANOVA was performed to compare the mean values of variables in control and BIBR1532 treated groups. LN18 cells showed a significant dose dependent cytotoxic effect after treatment with BIBR1532. hTERT mRNA expression in cells treated with 25, 100 and 200 μM BIBR1532 treated groups was decreased ~ 21, ~ 61.2, and ~ 77%, respectively (p < 0.05). We also observed that, BIBR1532 treatment reduced the expression of hTERT protein in LN18 cells in a dose dependent manner. The Flow cytometry data showed that, the drug induced significant increase in the total percentage of apoptotic cells with 200 μM concentration of BIBR1532 at all time points. BIBR1532 exhibited potent inhibition of telomerase activity in a dose-dependent manner in LN18 cells. BIBR1532 could induce apoptosis in LN18 cells through the downregulation of telomerase activity at transcriptional and translational level. We conclude that BIBR1532 may be a therapeutic agent to suppress telomerase activity, however, further efforts are necessary in order to explore this therapeutic strategy.

Telomerase Reverse Transcriptase and p53 Regulate Mammalian Peripheral Nervous System and CNS Axon Regeneration Downstream of c-Myc

“…Therefore, we investigated whether p53 acted downstream of c-Myc and TERT in sensory neurons to control axon regeneration. Indeed, the specific TERT inhibitor BIBR1532, which has been shown to reduce the protein level of TERT (Lavanya et al, 2018), also led to reduced p53 level in sensory neurons (Fig. 8 A, B), indicating that p53 was regulated by the c-Myc-TERT signaling in sensory neurons.…”

“…One potential explanation is that in postmitotic neurons TERT is localized in mitochondria to reduce oxidative stress and protect neurons from apoptosis (Liu et al, 2018). Functionally, inhibition of TERT with a specific pharmacological inhibitor BIBR1532 (Lavanya et al, 2018) impaired regenerative axon growth of sensory neurons in a dose-dependent manner without any toxic effects on neuronal survival (Fig. 4G-I ).…”

TERTinhibition leads to reduction ofIL‐6 expression induced by palmitic acid and interferes with the protective effects of tibolone in an astrocytic cell model

“…Because TERT protein has several non‐canonical functions, its increase could attenuate the detrimental effects induced by PA on cell death. Taking this into account, we aimed to evaluate the role of TERT in T98G cells using a chemical compound (BIBR1532), which is known to inhibit telomerase protein via a reduction of gene and protein expression . Our results suggest that telomerase was involved in the protection by tibolone against cell death induced by PA.…”

“…BIRB1532 induces an inhibition of telomerase activity by interacting with a motif involved in DNA binding . Moreover, it has been observed that this compound is able to reduce TERT gene and telomerase protein expression …”

Therapeutic strategies for targeting telomerase in cancer

“…There have been sufficient cellular activity data to indicate that BIBR1532 has an inhibitory effect on telomerase in human cancer cells with different histological origin, and it can result in progressive shortening of telomere and inhibition of cell proliferation in vitro and in vivo. Cell‐free experiments showed that telomerase inhibition by BIBR1532 was dose‐dependent (IC 50 = 100 nM in vitro) . At concentrations well above this IC 50 , BIBR1532 has no inhibitory effect on DNA polymerase, RNA polymerase, and HIV‐RT probably because HIV‐RT does not have the FVYL motif.…”