Oxidative stress resulting from reactive oxygen species (ROS) is known to play a key role in numerous neurological disorders, including neuropathic pain. Morphine is one of the commonly used opioids for pain management. However, long-term administration of morphine results in morphine antinociceptive tolerance (MAT) through elevation of ROS and suppression of natural antioxidant defense mechanisms. Recently, mesoporous polydopamine (MPDA) nanoparticles (NPS) have been known to possess strong antioxidant properties. We speculated that morphine delivery through an antioxidant nanocarrier might be a reasonable strategy to alleviate MAT. MPDAs showed a high drug loading efficiency of ∼50%, which was much higher than conventional NPS. Spectral and in vitro studies suggest a superior ROS scavenging ability of NPS. Results from a rat neuropathic pain model demonstrate that MPDA-loaded morphine (MPDA@Mor) is efficient in minimizing MAT with prolonged analgesic effect and suppression of pro-inflammatory cytokines. Additionally, serum levels of liver enzymes and levels of endogenous antioxidants were measured in the liver. Treatment with free morphine resulted in elevated levels of liver enzymes and significantly lowered the activities of endogenous antioxidant enzymes in comparison with the control and MPDA@Mor-treated group. Histopathological examination of the liver revealed that MPDA@Mor can significantly reduce the hepatotoxic effects of morphine. Taken together, our current work will provide an important insight into the development of safe and effective nano-antioxidant platforms for neuropathic pain management.

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Neuropathic pain, resulting from the dysfunction of the peripheral and central nervous system, occurs in a variety of pathological conditions including trauma, diabetes, cancer, HIV, surgery, multiple sclerosis, ischemic attack, alcoholism, spinal cord damage, and many others. Despite the availability of various treatment strategies, the percentage of patients achieving adequate pain relief remains low. The clinical failure of most effective drugs is often not due to a lack of drug efficacy but due to the dose-limiting central nervous system (CNS) toxicity of the drugs that preclude dose escalation. There is a need for cross-disciplinary collaborations to meet these challenges. In this regard, the integration of nanotechnology with neuroscience is one of the most important fields. In recent years, promising preclinical research has been reported in this field. This review highlights the current challenges associated with conventional neuropathic pain treatments, the scope for nanomaterials in delivering drugs across the blood−brain barrier, and the state and prospects of nanomaterials for the management of neuropathic pain.

Neuropathic pain (NP), is a chronic pain resulting from nerve injury, with limited treatment options. Teneligliptin (TEN) is a dipeptidyl peptidase-4 inhibitor (DPP-4i) approved to treat type 2 diabetes. DPP-4is prevent the degradation of the incretin hormone glucagon-like peptide 1 (GLP-1) and prolong its circulation. Apart from glycemic control, GLP-1 is known to have antinociceptive and anti-inflammatory effects. Herein, we investigated the antinociceptive properties of TEN on acute pain, and partial sciatic nerve transection (PSNT)-induced NP in Wistar rats. Seven days post PSNT, allodynia and hyperalgesia were confirmed as NP, and intrathecal (i.t) catheters were implanted and connected to an osmotic pump for the vehicle (1 μL/h) or TEN (5 μg/1 μL/h) or TEN (5 μg) + GLP-1R antagonist Exendin-3 (9–39) amide (EXE) 0.1 μg/1 μL/h infusion. The tail-flick response, mechanical allodynia, and thermal hyperalgesia were measured for 7 more days. On day 14, the dorsal horn was harvested and used for Western blotting and immunofluorescence assays. The results showed that TEN had mild antinociceptive effects against acute pain but remarkable analgesic effects against NP. Furthermore, co-infusion of GLP-1R antagonist EXE with TEN partially reversed allodynia but not tail-flick latency. Immunofluorescence examination of the spinal cord revealed that TEN decreased the immunoreactivity of glial fibrillary acidic protein (GFAP). Taken together, our findings suggest that TEN is efficient in attenuation of PSNT-induced NP. Hence, the pleiotropic effects of TEN open a new avenue for NP management.

Morphine (MOR) is a commonly prescribed drug for the treatment of moderate to severe diabetic neuropathic pain (DNP). However, long-term MOR treatment is limited by morphine analgesic tolerance (MAT). The activation of microglial cells and the release of glia-derived proinflammatory cytokines are known to play an important role in the development of MAT. In this study, we aimed to investigate the effects of the dipeptidyl peptidase-4 inhibitor (DPP-4i) teneligliptin (TEN) on MOR-induced microglial cell activation and MAT in DNP rats. DNP was induced in four groups of male Wistar rats through a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg, freshly dissolved in 5 mmol/L citrate buffer, pH 4.5). Sham rats were administered with the vehicle. Seven days after STZ injection, all rats were implanted with an intrathecal (i.t) catheter connected to a mini-osmotic pump, divided into five groups, and infused with the following combinations: sham + saline (1 µL/h, i.t), DNP + saline (1 µL/h, i.t), DNP + MOR (15 µg/h, i.t), DNP + TEN (2 µg/h, i.t), and DNP + MOR (15 µg/h, i.t) + TEN (2 µg/h, i.t) for 7 days at a rate of 1 μL/h. The MAT was confirmed through the measurement of mechanical paw withdrawal threshold and tail-flick tests. The mRNA expression of neuroprotective proteins nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1) in the dorsal horn was evaluated by quantitative PCR (qPCR). Microglial cell activation and mononucleate cell infiltration in the spinal cord dorsal horn were assessed by immunofluorescence assay (IFA) and Western blotting (WB). The results showed that co-infusion of TEN with MOR significantly attenuated MAT in DNP rats through the restoration of neuroprotective proteins Nrf2 and HO-1 and suppression of microglial cell activation in the dorsal horn. Though TEN at a dose of 2 μg has mild antinociceptive effects, it is highly effective in limiting MAT.

Purpose: We have synthesized a series of bifunctional molecules, which are able to induce DNA interstrand crosslinks and inhibit angiogenesis as potent anticancer agents [1] and leads to develop new hybrids molecules. To analyze one of the novel bifunctional agent BO-2762 activity in consensus molecular subtype (CMS) classified as colorectal cancer (CRC) which are classified into four subtypes [ CMS1, MSI-immune; CMS2, epithelial and canonical; CMS3, epithelial and metabolic; and CMS4, mesenchymal] in in vitro and in vivo models. Experimental Design: We analyzed the anticancer effect of BO-2762 in CMS primary colorectal cancer cells which are reported in previous studies [2] and their respective xenografts (CMS-1: LoVo; CMS-2: LS1034; CMS-3: HT-29 and CMS-4: SW620). CMS provided a new platform to analyze BO-2762 functionalized subtype-specific sensitivity in CRC. Results: BO-2762 has a distinct bifunctional activity by DNA crosslinking in CRC cells and inhibiting angiogenesis in endothelial cells at IC50 of nanomolar to micromolar ranges. Angiogenesis inhibition was likely due to the suppression of VEGFR-2 phosphorylation in EA.hy 926 cells. Additionally, BO-2762 could inhibit cell migration, invasion, and induce apoptotic cell death in CRC. In our observation, no subtype-sensitivity has observed in in vitro conditions as reported in previous studies [3]. Using xenograft models, 20 mg/kg BO-2762 suppressed remarkably LoVo (CMS-1), and SW620 (CMS-4) subtypes, moderately in LS1034 (CMS-2) which was administrated via i.v. injection. However, HT29 cells classified as metabolic dysregulated, which is the CMS-3 subtype, have shown resistance to BO-2762. Conclusion: BO-2762 functions as an angiogenesis inhibitor by inhibiting the phosphorylation of VEGFR2 and inhibits the DNA synthesis by cross-linking the DNA. Consequently, BO-2762 was shown to profoundly suppress the growth of CRC xenografts of CMS-1 and 4 subtypes but not that of CMS-2 and 3. Accordingly, BO-2762 has great potential for further development as a specific anti-CRC agent against CMS-1 and 4 subtypes and lead the further investigation on how to overcome the resistance of metabolic dysregulated CMS-3 subtype as a fundamental question that warrants our investigation. References: 1. J Med Chem, 2019. 62(5): p. 2404-2418. 2. Clin Cancer Res, 2018. 24(4): p. 794-806. 3. Neoplasia, 2020. 22(9): p. 365-375 Citation Format: Vaikar Navakanth Rao, Ramajayam Kuppuswamy, Kuo Chu Lai, Tsann-Long Su, Te-Chang Lee. A dual functional agent inhibits the angiogenesis and DNA synthesis resulting in the growth suppression of consensus molecular subtypes 1 and 4 in colorectal cancer xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2648.

Background: Colorectal cancer (CRC) is the second-leading death of all cancers in the world. Metastasis is the basis for cause of death in patients with CRC. Currently, combination of anti-VEGF therapy and DNA damaging agents, such as Bevacizumab + FOLFOX, has become the first-line therapy in managing colorectal cancer progression. To mimic the first-line therapy, we have conjugated the angiogenesis inhibitory and the DNA damaging moieties to form a bifunctional hybrid molecule. The purpose of this study is to prove the efficacy and safety of the novel hybrid molecule in treatment of CRC cells in mouse models. Materials and methods: The novel hybrid molecule, designated as BO-2762, was synthesized as previously reported. The anti-proliferative activity was analyzed by PrestoBlue® assay in a variety of CRC cell lines and CRC patient derived organoids (PDO). DNA damage was analyzed by alkaline gel electrophoresis and comet assay. Antiangiogenic property was assessed using the docking model, in vitro tube formation, and in vivo angiogenesis methods. Anti-tumor efficacy of BO-2762 was determined using xenografts of CRC cell lines and PDOs at 20 mg/kg via tail vein injection. For safety profiling and toxicology study, the ICR mice model was adopted for various pathological analyses. Results: The values of anti-proliferative IC50 of BO-2762 against a panel of 11 CRC and 10 PDO cell lines were ranged between 0.5 to 4.5 µM. Subsequently, we demonstrated that BO-2762 induced DNA inter-strand cross-linking (ICL) by alkaline agarose gel electrophoresis. Apparently, ICLs caused significant cell cycle arrest at the S phase, and subsequently triggered apoptosis. The angiogenesis inhibition by BO-2762 was also confirmed by in vitro tube formation assay and Direct In Vivo Angiogenesis Assay. The anti-CRC activity of BO-2762 was assessed using xenografts of CRC cells, derived from metastatic sites (LoVo and SW620 cells) and from primary sites (LS1034 and HT-29 cells). Via tail vein injection of BO-2762 at 20 mg/kg for 10 times, the growth of LoVo, SW620, LS1034, and HT-29 cells was suppressed by 85.8%, 83.0%, 75.4%, and 44.8% respectively. In addition, BO-2762 also significantly suppressed the growth of metastatic PDOs (T53 and T112) by 90%. Biosafety analysis showed promising safety parameters in blood chemistry and major organs. Conclusions: Our present results have shown that conjugated hybrid molecule with DNA cross-linking and anti-angiogenic activity is likely a novel approach to treat patients with CRC. Citation Format: Vaikar Navakanth Rao, Kuo-Chu Lai, Chin-Hung Liu, Shung-Haur Yang, Jeou-Yuan Chang, Tsann-Long Su, Te-Chang Lee. A novel hybrid with anti-angiogenic and DNA crosslinking activities potently suppresses the growth of colorectal cancer cells and patient-derived organoids in mice [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr B010.

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