Effect of Lipoic Acid on the Biochemical Mechanisms of Resistance to Bortezomib in SH-SY5Y Neuroblastoma Cells

Spatial sequestration of activated-caspase 3 in aggresomes mediates resistance of neuroblastoma cell to bortezomib treatment

Neuroblastoma (NB) is the most common pediatric tumor and is currently treated by several types of therapies including chemotherapies, such as bortezomib treatment. However, resistance to bortezomib is frequently observed by mechanisms that remain to be deciphered. Bortezomib treatment leads to caspase activation and aggresome formation. Using models of patients-derived NB cell lines with different levels of sensitivity to bortezomib, we show that the activated form of caspase 3 accumulates within aggresomes of NB resistant cells leading to an impairment of bortezomib-induced apoptosis and increased cell survival. Our findings unveil a new mechanism of resistance to chemotherapy based on an altered subcellular distribution of the executioner caspase 3. This mechanism could explain the resistance developed in NB patients treated with bortezomib, emphasizing the potential of drugs targeting aggresomes.

In vitro Evaluation of Selective Cytotoxic Activity of Chaerophyllum macropodum Boiss. on Cultured Human SH-SY5Y Neuroblastoma Cells

Neuroblastoma is the most common solid tumor in children. New treatment approaches are needed because of the harmful side effects and costs of the methods used in the treatment of neuroblastoma. Medicinal and aromatic plants are important for new treatment approaches due to their minimal side effects and economic advantages. Therefore, the present study was carried out to examine the cytotoxic effect of Chaerophyllum macropodum extract on human neuroblastoma (SH-SY5Y) and fibroblast (HDFa) cell lines. 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase release (LDH) assays were used to determine the cytotoxic effect of C. macropodum. The extracts were analyzed for their phenolic content by HPLC-PDA. Major components were determined as 63.600% o-coumaric acid, 15.606% catechine hydrate, 8.713% rosmarinic acid, 4.376% clorogenic acid, and 3.972% salicylic acid. The obtained results from cytotoxicity testing revealed that C. macropodum exerted a significant cytotoxic effect on human neuroblastoma cells at all tested concentrations (p < 0.05). But it did not lead to any cytotoxic potential on human fibroblasts. As a result, the obtained data clearly revealed C. macropodum exerted a selective cytotoxic action on neuroblastoma cells for the first time.

Production of levan from Bacillus subtilis var. natto and apoptotic effect on SH-SY5Y neuroblastoma cells

Levan is a high-valued polysaccharide of fructose produced by several microbial species. These polysaccharides have been described as effective therapeutic agents in some human disease conditions, such as cancer, heart diseases and diabetes. The objective of this study was to examine the effect of levan (β-(2 → 6)-fructan) produced through sucrose fermentation by B. subtilis var. natto on the proliferation rate, cytotoxicity, and apoptosis of human neuroblastoma SH-SY5Y cells. It was obtained 41.44 g/L of levan in 18 h by biotechnological fermentation and SH-SY5Y cells were exposed to 1000 μg/mL of levan. The treatment with 1000 μg/mL of levan induced apoptosis in SH-SY5Y cancer cells by the significant increase in Annexin V/7-AAD and caspase 3/7 activation, but did not decrease proliferation or triggered a cytotoxic effect. 1000 μg/mL levan treatment is a promising therapeutic strategy for SH-SY5Y neuroblastoma cells.

Lipoic acid. Kinetics and pluripotent biological properties and derivatives

Lipoic acid (LA) is globally known and its supplements are widely used. Despite its importance for the organism it is not considered a vitamin any more. The multiple metabolic forms and the differences in kinetics (absorption, distribution and excretion), as well as the actions of its enantiomers are analysed in the present article together with its biosynthetic path. The proteins involved in the transfer, biotransformation and activity of LA are mentioned. Furthermore, the safety and the toxicological profile of the compound are commented, together with its stability issues. Mechanisms of lipoic acid intervention in the human body are analysed considering the antioxidant and non-antioxidant characteristics of the compound. The chelating properties, the regenerative ability of other antioxidants, the co-enzyme activity and the signal transduction by the implication in various pathways will be discussed in order to be elucidated the pleiotropic effects of LA. Finally, lipoic acid integrating analogues are mentioned under the scope of the multiple pharmacological actions they acquire towards degenerative conditions.

Synthesis of propargylamine mycophenolate analogues and their selective cytotoxic activity towards neuroblastoma SH-SY5Y cell line

Twenty six propargylamine mycophenolate analogues were designed and synthesized from mycophenolic acid 1 employing a key step A³-coupling reaction. Their cytotoxic activity was examined against six cancer cell lines. Compounds 6a, 6j, 6t, 6u, and 6z exhibited selective cytotoxicity towards neuroblastoma (SH-SY5Y) cancer cells and were less toxic to normal cells in comparison to the lead compound, MPA 1 and a standard drug, ellipticine. Molecular docking results suggested that compound 6a is fit well in the key amino acid of three proteins (CDK9, EGFR, and VEGFR-2) as targets in cancer therapy. The propargylamine mycophenolate scaffold might be a valuable starting point for development of new neuroblastoma anticancer drugs.

The Road of Solid Tumor Survival: From Drug-Induced Endoplasmic Reticulum Stress to Drug Resistance

Endoplasmic reticulum stress (ERS), which refers to a series of adaptive responses to the disruption of endoplasmic reticulum (ER) homeostasis, occurs when cells are treated by drugs or undergo microenvironmental changes that cause the accumulation of unfolded/misfolded proteins. ERS is one of the key responses during the drug treatment of solid tumors. Drugs induce ERS by reactive oxygen species (ROS) accumulation and Ca²⁺ overload. The unfolded protein response (UPR) is one of ERS. Studies have indicated that the mechanism of ERS-mediated drug resistance is primarily associated with UPR, which has three main sensors (PERK, IRE1α, and ATF6). ERS-mediated drug resistance in solid tumor cells is both intrinsic and extrinsic. Intrinsic ERS in the solid tumor cells, the signal pathway of UPR-mediated drug resistance, includes apoptosis inhibition signal pathway, protective autophagy signal pathway, ABC transporter signal pathway, Wnt/β-Catenin signal pathway, and noncoding RNA. Among them, apoptosis inhibition is one of the major causes of drug resistance. Drugs activate ERS and its downstream antiapoptotic proteins, which leads to drug resistance. Protective autophagy promotes the survival of solid tumor cells by devouring the damaged organelles and other materials and providing new energy for the cells. ERS induces protective autophagy by promoting the expression of autophagy-related genes, such as Beclin-1 and ATG5–ATG12. ABC transporters pump drugs out of the cell, which reduces the drug-induced apoptosis effect and leads to drug resistance. In addition, the Wnt/β-catenin signal pathway is also involved in the drug resistance of solid tumor cells. Furthermore, noncoding RNA regulates the ERS-mediated survival and death of solid tumor cells. Extrinsic ERS in the solid tumor cells, such as ERS in immune cells of the tumor microenvironment (TME), also plays a crucial role in drug resistance by triggering immunosuppression. In immune system cells, ERS in dendritic cells (DCs) and myeloid-derived suppressor cells (MDSCs) influences the antitumor function of normal T cells, which results in immunosuppression. Meanwhile, ERS in T cells can also cause impaired functioning and apoptosis, leading to immunosuppression. In this review, we highlight the core molecular mechanism of drug-induced ERS involved in drug resistance, thereby providing a new strategy for solid tumor treatment.

Heme Oxygenase Inhibition Sensitizes Neuroblastoma Cells to Carfilzomib

Neuroblastoma (NB) is an embryonic malignancy affecting the physiological development of adrenal medulla and paravertebral sympathetic ganglia in early infancy. Proteasome inhibitors (PIs) (i.e., carfilzomib (CFZ)) may represent a possible pharmacological treatment for solid tumors including NB. In the present study, we tested the effect of a novel non-competitive inhibitor of heme oxygenase-1 (HO-1), LS1/71, as a possible adjuvant therapy for the efficacy of CFZ in neuroblastoma cells. Our results showed that CFZ increased both HO-1 gene expression (about 18-fold) and HO activity (about 8-fold), following activation of the ER stress pathway. The involvement of HO-1 in CFZ-mediated cytotoxicity was further confirmed by the protective effect of pharmacological induction of HO-1, significantly attenuating cytotoxicity. In addition, HO-1 selective inhibition by a specific siRNA increased the cytotoxic effect following CFZ treatment in NB whereas SnMP, a competitive pharmacological inhibitor of HO, showed no changes in cytotoxicity. Our data suggest that treatment with CFZ produces ER stress in NB without activation of CHOP-mediated apoptosis, whereas co-treatment with CFZ and LS1/71 led to apoptosis activation and CHOP expression induction. In conclusion, our study showed that treatment with the non-competitive inhibitor of HO-1, LS1 / 71, increased cytotoxicity mediated by CFZ, triggering apoptosis following ER stress activation. These results suggest that PIs may represent a possible pharmacological treatment for solid tumors and that HO-1 inhibition may represent a possible strategy to overcome chemoresistance and increase the efficacy of chemotherapic regimens.

Biochemical and clinical relevance of alpha lipoic acid: antioxidant and anti-inflammatory activity, molecular pathways and therapeutic potential

BACKGROUND

The molecular nature of lipoic acid (LA) clarifies its capability of taking part to a variety of biochemical reactions where redox state is meaningful. The pivotal action of LA is the antioxidant activity due to its ability to scavenge and inactivate free radicals. Furthermore, LA has been shown to chelate toxic metals both directly and indirectly by its capability to enhance intracellular glutathione (GSH) levels. This last property is due to its ability to interact with GSH and recycle endogenous GSH. LA exhibits significant antioxidant activity protecting against oxidative damage in several diseases, including neurodegenerative disorders. Interestingly, LA is unique among natural antioxidants for its capability to satisfy a lot of requirements, making it a potentially highly effective therapeutic agent for many conditions related with oxidative damage. In particular, there are evidences showing that LA has therapeutic activity in lowering glucose levels in diabetic conditions. Similarly, LA supplementation has multiple beneficial effects on the regression of the mitochondrial function and on oxidative stress associated with several diseases and aging.

AIM

The aim of the present review is to describe the molecular mechanisms underlying the beneficial effects of LA under various experimental conditions and disease and how to exploit such effect for clinical purposes.

CONCLUSION

LA has pleiotropic effects in different pathways related with several diseases, its use as a potential therapeutic agent is very promising.