Synergistic Apoptotic Effect of Naringenin on enhancing the Anti-Glioma Efficacy of Temozolomide in an in vitro Experimental Model

Abstract

Glioma is one of the most devastating and difficult-totreat brain tumors with a very poor prognosis. Despite the current treatment modalities, the overall survival rate is only 5% contributing to a high mortality rate. Nevertheless, of emerging treatment strategies, there is still a rising need for novel mitigation strategies to counteract glioma aggressiveness. One attempt towards this long-term goal was made in this study to reveal the combined efficacy of naringenin, a bioactive flavonoid on enhancing the anti-glioma potency of temozolomide in C6 glioma cells. The cytotoxic effect of temozolomide and naringenin, both individually and in combination was assessed by employing MTT assay. The synergistic effect of the drugs temozolomide and naringenin was determined by calculating the combination index. To confirm the presence of apoptotic changes in the cells at morphological level, acridine orange/ethidium bromide staining was performed. Further, the modulatory effects of the drugs on apoptotic genes, caspase-3 and BCL-2 were evaluated using quantitative real time-PCR. Interestingly, we found that the combinatorial drug treatment was in consensus and effectively inhibited the growth of C6 glioma cells in a dose-dependent manner. Furthermore, this combinatorial drug treatment significantly up-regulated the expression of the proapoptotic gene, caspase-3 and down-regulated the anti-apoptotic gene BCL-2 suggesting a shift of equilibrium towards apoptosis. Our findings suggest that naringenin can be employed as a potent drug to enhance the anti-glioma efficacy of temozolomide and could be therapeutically exploited for the management of glioma.

Dynamics of repurposing synthetic and natural compounds against WNT/β-Catenin signaling in glioma- Anin vivoapproach

“…Nevertheless, the process of identifying and validating the potent candidates for repurposing ranges from experimental ( in vitro and in vivo ) studies to randomized clinical trials (Saeidnia et al 2015). While considering drug repurposing for malignancies like glioma, the therapeutic efficacy of the drugs as monotherapies seems to be less efficient (Ho and Ho 2021); thereof, the focus has now shifted to identify synergistic combination therapies employing two or more drugs (Brown et al 2008; Kuduvalli et al 2021; Daisy et al 2021). In line with this concept, herein, we have presented the in vivo evidence for GB treatment enhancement using a quadruple- combinatorial drug treatment (TCNP) comprising a cocktail of both synthetic and natural derivatives.…”

“…Also, repurposing natural derivatives such as flavonoids and marine compounds had gained increasing interest in GB research (Tseng et al 2004;Do et al 2010;Sabarinathan et al 2011;Lu et al 2012;Du et al 2013;Daisy et al 2021). For instance, naringenin (NAR), a (which was not certified by peer review) is the author/funder.…”

“…Also, repurposing natural derivatives such as flavonoids and marine compounds had gained increasing interest in GB research (Tseng et al 2004;Do et al 2010;Sabarinathan et al 2011;Lu et al 2012;Du et al 2013;Daisy et al 2021). For instance, naringenin (NAR), a bioactive flavonoid, was reported to alter the mitogen-activated protein kinase (MAPK) signaling pathway in glioma and induce apoptosis via modulation of Bax/BCL-2 ratio (Sabarinathan et al 2010;Aroui et al 2016).…”

“…For instance, the synthetic compound, chloroquine (CHL), the drug of choice for malaria, has recently gained importance for its off-target activity on GB, wherein Sotelo et al ., and Briceno et al ., had reported that addition of CHL as adjuvant to TMZ had significantly prolonged the survival of GB patients and several clinical trials are underway (Briceño et al 2003; Sotelo et al 2006). Also, repurposing natural derivatives such as flavonoids and marine compounds had gained increasing interest in GB research (Tseng et al 2004; Do et al 2010; Sabarinathan et al 2011; Lu et al 2012; Du et al 2013; Daisy et al 2021). For instance, naringenin (NAR), a bioactive flavonoid, was reported to alter the mitogen-activated protein kinase (MAPK) signaling pathway in glioma and induce apoptosis via modulation of Bax/BCL-2 ratio (Sabarinathan et al 2010; Aroui et al 2016).…”

“…Interestingly, our previous research found that co-administration of these drugs as a quadruple-drug combination (TCNP) had profound effect on hampering malignant glioma proliferation and inducing apoptosis in vitro in C6, U-87 MG and LN229 glioma cells and in vivo (Daisy et al 2021; Precilla et al 2022). Initially, the dual-drug and triple-drug combinations were assessed for their cytotoxicity effects in all the three glioma cell lines (Precilla et al 2022).…”