Effect of α-tocopheryl succinate on the molecular damage induced by indomethacin in C6 glioma cells

Indomethacin-encapsulated PLGA nanoparticles improve therapeutic efficacy by increasing apoptosis and reducing motility in glioblastoma cells

Glioblastoma, with a low survival rate, is an aggressive and difficult-to-treat lethal type of brain cancer. Indomethacin (IND), a non-steroidal anti-inflammatory drug, has antitumoral activity in many cancers, including gliomas. However, its poor aqueous solubility is a critical issue. Nanomaterials are crucial tools for overcoming solubility problems and facilitating drug delivery. Herein, a polymeric nanoparticle system, poly(lactic-co-glycolic acid) (PLGA) was used to encapsulate IND. Although PLGA is an FDA-approved copolymer for drug delivery, no trials with IND-loaded PLGA-NPs have been conducted to treat brain tumors. Encapsulation success was revealed by DLS, zeta potential, TEM, and FTIR analysis; IND/PLGA-NPs had nanoscale particle size (160.6 nm), narrow size distribution (0.230, PDI), and good stability (-23.9 mV). Fluorescence imaging showed that PLGA-NPs can penetrate U-87MG cells. Short-term/one-hour treatment with bound-IND increased the free-IND effect in gliomas by ⁓10 times/48h and 12.39 times/72h. Even against long-term exposure to IND, IND/PLGA-NP treatment revealed a highly marked result; the IC50 value of bound-IND (treatment-time:1h, analysis at 48h) was ∼200µM, IC50 value of free-IND (treatment-time:48h) was ∼390µM. Furthermore, IND/PLGA-NPs' anticancer activity (100 µM of IND/1h, analysis at 48h) was also supported by induced apoptosis and reduced migration/colony formation in glioma cells. All evidence suggests that IND/PLGA-NPs may be a potentially promising agent for treating gliomas.

Nanoemulsion Composed of α-Tocopherol Succinate and Dequalinium Shows Mitochondria-Targeting and Anticancer Effects

Targeted drugs have been used to treat mitochondrial dysfunction-related diseases, including metabolic disorders and cancer; however, targeting and penetrating intracellular organelles remains a challenge. Dominant targeting approaches for therapeutic delivery are detailed in many nanoemulsion studies and show the tremendous potential of targeted delivery to inhibit cancer cell growth. Dequalinium (DQA) and α-tocopherol succinate (α-TOS) are good agents for targeting mitochondria. In this study, we aimed to develop a mitochondria-targeting emulsion, using DQA and α-TOS (DTOS), for cancer treatment. DTOS emulsions of 150-170 nm in diameter were formulated using homogenization. DQA and α-TOS were used as bifunctional agents (surfactants) to stabilize the nanoemulsion and anticancer drugs. Various molar ratios of DQA and α-TOS were tested to determine the optimal condition, and DTOS 5-5 was selected for further study. The DTOS emulsion showed improved stability, as evidenced by its ability to remain stable for three years at room temperature. This stability, combined with its effective targeting of mitochondria, led to inhibition of 71.5% of HeLa cells after 24 h. The DTOS emulsion effectively inhibited spheroid growth in the 3D model, as well as prevented the growth of HeLa cells grafted onto zebrafish larvae. These results highlight the DTOS emulsion's promising potential for mitochondria-targeting and cancer treatment.

In vitro antiglioma action of indomethacin is mediated via AMP-activated protein kinase/mTOR complex 1 signalling pathway

We investigated the role of the intracellular energy-sensing AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway in the in vitro antiglioma effect of the cyclooxygenase (COX) inhibitor indomethacin. Indomethacin was more potent than COX inhibitors diclofenac, naproxen, and ketoprofen in reducing the viability of U251 human glioma cells. Antiglioma effect of the drug was associated with p21 increase and G₂M cell cycle arrest, as well as with oxidative stress, mitochondrial depolarization, caspase activation, and the induction of apoptosis. Indomethacin increased the phosphorylation of AMPK and its targets Raptor and acetyl-CoA carboxylase (ACC), and reduced the phosphorylation of mTOR and mTOR complex 1 (mTORC1) substrates p70S6 kinase and PRAS40 (Ser183). AMPK knockdown by RNA interference, as well as the treatment with the mTORC1 activator leucine, prevented indomethacin-mediated mTORC1 inhibition and cytotoxic action, while AMPK activators metformin and AICAR mimicked the effects of the drug. AMPK activation by indomethacin correlated with intracellular ATP depletion and increase in AMP/ATP ratio, and was apparently independent of COX inhibition or the increase in intracellular calcium. Finally, the toxicity of indomethacin towards primary human glioma cells was associated with the activation of AMPK/Raptor/ACC and subsequent suppression of mTORC1/S6K. By demonstrating the involvement of AMPK/mTORC1 pathway in the antiglioma action of indomethacin, our results support its further exploration in glioma therapy.