ABSTRACT
The prognosis with pancreatic cancer is among the poorest of any human cancer. One of the important factors is the tumor hypoxia. Targeting tumor hypoxia is considered a desirable therapeutic option. However, it has not been translated into clinical success in the treatment of pancreatic cancer. With enhanced cytotoxicities against hypoxic pancreatic cancer cells, BE-43547A2 (BE) may serve as a promising template for hypoxia target strategy. Here, based on rational modification, a BE prodrug (NMP-BE) is encapsulated into sulfonated azocalix[5]arene (SAC5A) to generate a supramolecular dual hypoxia-responsive complex NMP-BE@SAC5A. Benefited from the selective load release within cancer cells, NMP-BE@SAC5A markedly suppresses tumor growth at low dose in pancreatic cancer cells xenograft murine model without developing systemic toxicity. This research presents a strategy for the modification of covalent compounds to achieve efficient delivery within tumors, a horizon for the realization of safe and reinforced hypoxia target therapy using a simple approach.
Subject(s)
Pancreatic Neoplasms , Humans , Animals , Mice , Pancreatic Neoplasms/drug therapy , Pancreas , Alkanesulfonates , Disease Models, Animal , Hypoxia , Pancreatic NeoplasmsABSTRACT
Trigeminal neuropathic pain (TNP) is a significant health problem but the involved mechanism has not been completely elucidated. Toll-like receptors (TLRs) have recently been demonstrated to be expressed in the dorsal root ganglion and involved in chronic pain. Here, we show that TLR8 was persistently increased in the trigeminal ganglion (TG) neurons in model of TNP induced by partial infraorbital nerve ligation (pIONL). In addition, deletion or knockdown of Tlr8 in the TG attenuated pIONL-induced mechanical allodynia, reduced the activation of ERK and p38-MAPK, and decreased the expression of pro-inflammatory cytokines in the TG. Furthermore, intra-TG injection of the TLR8 agonist VTX-2337 induced pain hypersensitivity. VTX-2337 also increased the intracellular Ca2+ concentration, induced the activation of ERK and p38, and increased the expression of pro-inflammatory cytokines in the TG. These data indicate that TLR8 contributes to the maintenance of TNP through increasing MAPK-mediated neuroinflammation. Targeting TLR8 signaling may be effective for the treatment of TNP.
Subject(s)
Neuralgia , Toll-Like Receptor 8 , Trigeminal Neuralgia , Animals , Hyperalgesia , Mice , Trigeminal GanglionABSTRACT
Toll-like receptors (TLRs) are nucleic acid-sensing receptors and have been implicated in mediating pain and itch. Here we report that Tlr8 -/- mice show normal itch behaviors, but have defects in neuropathic pain induced by spinal nerve ligation (SNL) in mice. SNL increased TLR8 expression in small-diameter IB4+ DRG neurons. Inhibition of TLR8 in the DRG attenuated SNL-induced pain hypersensitivity. Conversely, intrathecal or intradermal injection of TLR8 agonist, VTX-2337, induced TLR8-dependent pain hypersensitivity. Mechanistically, TLR8, localizing in the endosomes and lysosomes, mediated ERK activation, inflammatory mediators' production, and neuronal hyperexcitability after SNL. Notably, miR-21 was increased in DRG neurons after SNL. Intrathecal injection of miR-21 showed the similar effects as VTX-2337 and inhibition of miR-21 in the DRG attenuated neuropathic pain. The present study reveals a previously unknown role of TLR8 in the maintenance of neuropathic pain, suggesting that miR-21-TLR8 signaling may be potential new targets for drug development against this type of chronic pain.
Subject(s)
Chronic Pain/immunology , Ganglia, Spinal/immunology , MicroRNAs/immunology , Neuralgia/immunology , Signal Transduction/immunology , Toll-Like Receptor 8/immunology , Animals , Chronic Pain/drug therapy , Chronic Pain/genetics , Chronic Pain/pathology , Endosomes/immunology , Endosomes/pathology , Ganglia, Spinal/pathology , Lysosomes/immunology , Lysosomes/pathology , Mice , Mice, Inbred ICR , Mice, Knockout , MicroRNAs/genetics , Neuralgia/drug therapy , Neuralgia/genetics , Neuralgia/pathology , Neurons/immunology , Neurons/pathology , Signal Transduction/genetics , Toll-Like Receptor 8/geneticsABSTRACT
Autophagy is a process of cellular self-cannibalization, and provides an adaptive mechanism to protect cells against diverse pathological settings. Following peripheral nerve injury, autophagic process was changed in Schwann cells and spinal neurons and glial cells, implicating a vital role of autophagy in chronic pain. However, little is known about the role of autophagy in dorsal root ganglion (DRG) in neuropathic pain. In the present study, we investigated the autophagic process in DRG and its effect on neuropathic pain induced by L5 spinal nerve ligation (SNL). The level of microtubule associated protein 1 light chain 3 (LC3)-II, a general marker for autophagy, was increased in L5 DRG after SNL. Immunofluorescence staining showed that LC3-II puncta were observed in DRG neurons after SNL. Injection of autophagy inducer rapamycin into L5 DRG before or after SNL dose-dependently attenuated neuropathic pain. The expression of LC3 was enhanced in L5 DRG by rapamycin. These data suggest that the autophagy in L5 DRG neurons is a defensive reaction to L5 spinal nerve injury, and pharmacological enhancement of autophagy may be a potential treatment to prevent the onset and chronification of neuropathic pain.
