The Influence of Lentinan on the Capacity of Repair of DNA Damage and Apoptosis Induced by Paclitaxel in Mouse Bone Marrow Cells

Circulating immunotherapy strategy based on pyroptosis and STING pathway: Mn-loaded paclitaxel prodrug nanoplatform against tumor progression and metastasis

Immunotherapy has emerged as a promising strategy against tumors. However, its efficacy is limited by low immunogenicity, poor antigen presentation, and inadequate lymphocyte infiltration. Herein, we develop a nanoplatform (Mn-HSP) loaded with manganese ions (Mn2+) and paclitaxel (PTX) prodrug based on hyaluronic acid. PTX in Mn-HSP induces DNA damage and pyroptosis to release tumor-associated antigens (TAAs), enhancing tumor-specific adaptive immunity. Meanwhile, Mn2+ in Mn-HSP, together with PTX-induced DNA damage, activates the stimulator of interferon gene (STING) pathway to amplify innate immunity. Mn-HSP combines with adaptive and innate immunity, effectively enhancing the presentation of antigen-presenting cells (APCs) and promoting tumor infiltration of cytotoxic T lymphocytes (CTLs). In turn, the granzyme B (GZMB) secreted by CTLs triggers pyroptosis again, thereby establishing a "circulating immunotherapy" against tumors. Our results demonstrate that Mn-HSP efficiently inhibits primary breast tumors, as well as rechallenge tumors and lung metastasis in vivo. Therefore, the circulating immunotherapy that combines pyroptosis mediated adaptive immunity and STING pathway amplified innate immunity provides a novel strategy for enhancing tumor immunotherapy.

Subcritical Water Enhanced with Deep Eutectic Solvent for Extracting Polysaccharides from Lentinus edodes and Their Antioxidant Activities

In the present study, subcritical water extraction (SWE) assisted with deep eutectic solvent (DES) is used to extract Lentinus edodes polysaccharides (LEP). In addition, the antioxidant activity of the polysaccharide samples was also investigated. Based on a single factor test and response surface test, the optimal extraction factors were a liquid–solid solvent of 40:1 mL/g, extraction temperature of 147.23 °C, water content of 39.76% and extraction time of 17.58 min. Under these extraction conditions, the yield of LEP was 6.26 ± 0.08%. Compared with the SWE and hot water extraction (HWE), it improved by 19.24% and 17.01%, respectively. In addition, the results of monosaccharide composition, molecular weight, FT-IR, UV and SEM confirmed that the extracts had the features of polysaccharides. Interestingly, the polysaccharides obtained with the SWE assisted with the DES procedure showed a higher DPPH scavenging activity, hydroxyl radical scavenging activity and hydrogen peroxide scavenging activity, which indicated that the polysaccharides with this method had a stronger antioxidant activity. These findings demonstrated that the SWE-assisted DES is a strong method to obtain polysaccharides from Lentinus edodes for food, biopharmaceutical and other industrial production.

Lentinan protects against pancreatic β-cell failure in chronic ethanol consumption-induced diabetic mice via enhancing β-cell antioxidant capacity

Chronic ethanol consumption is a well-established independent risk factor for type 2 diabetes mellitus (T2DM). Recently, increasing studies have confirmed that excessive heavy ethanol exerts direct harmful effect on pancreatic β-cell mass and function, which may be a mechanism of pancreatic β-cell failure in T2DM. In this study, we evaluated the effect of Lentinan (LNT), an active ingredient purified from the bodies of Lentinus edodes, on pancreatic β-cell apoptosis and dysfunction caused by ethanol and the possible mechanisms implicated. Functional studies reveal that LNT attenuates chronic ethanol consumption-induced impaired glucose metabolism in vivo. In addition, LNT ameliorates chronic ethanol consumption-induced β-cell dysfunction, which is characterized by reduced insulin synthesis, defected insulin secretion and increased cell apoptosis. Furthermore, mechanistic assays suggest that LNT enhances β-cell antioxidant capacity and ameliorates ethanol-induced oxidative stress by activating Nrf-2 antioxidant pathway. Our results demonstrated that LNT prevents ethanol-induced pancreatic β-cell dysfunction and apoptosis, and therefore may be a potential pharmacological agent for preventing pancreatic β-cell failure associated with T2DM and stress-induced diabetes.

Discovery of Myricetin as a Potent Inhibitor of Human Flap Endonuclease 1, Which Potentially Can Be Used as Sensitizing Agent against HT-29 Human Colon Cancer Cells

Human flap endonuclease 1 (hFEN1) is instrumental in DNA replication and repair. It is able to cleave the 5' single-stranded protrusion (also known as 5' flap) resulting from strand displacement reactions. In light of its crucial functions, hFEN1 is now deemed as a nontrivial target in the DNA damage response system for anticancer drug development. Herein, we report that myricetin and some natural flavonoids are able to inhibit hFEN1. Structure-activity relationship, inhibitory mechanisms, molecular docking, and cancer cell-based assays have been performed. Our original findings expand the activity of flavonoids and may pave the way for flavonoid-assisted targeted cancer therapy.

Synergistic antitumor effect of combined paclitaxel with FEN1 inhibitor in cervical cancer cells

Studies on cervical cancer are urgently required to improve clinical outcomes. As a major anticancer drug for cervical cancer, paclitaxel has been used for many years in clinical therapy but its therapeutic efficacy is limited by common obstacle from cancer cells. The enhanced DNA repair pathways of cancer cells have been proved to survive DNA damage induced by chemotherapeutic drug. Inhibitors of specific DNA repair pathway can sensitize cancer cells to the treatment of chemotherapeutic drugs. In this paper we found that the effect of paclitaxel can be significantly improved when used in combination with FEN1 inhibitor SC13, suggesting a synergistic mechanism between the two compounds. Our studies suggest that FEN1 inhibition could be a novel strategy of tumor-targeting therapy for cervical cancer. Our work also revealed that paclitaxel demonstrates stronger synergistic effect with SC13 than other common used chemical drugs such as doxorubicin, carboplatin or camptothecin on cervical cancer cells.

In vitro protective effects of botryosphaeran, a (1→3;1→6)-β-d-glucan, against mutagens in normal and tumor rodent cells

Botryosphaeran (BOT) is an exocellular β-d-glucan (carbohydrate biopolymer) of the (1→3;1→6)-linked type produced by Botryosphaeria rhodina MAMB-05. The cytotoxic, mutagenic, genotoxic, and protective effects of this substance were evaluated in Chinese hamster lung fibroblasts (V79) and rat hepatocarcinoma cells (HTC) by the micronucleus test (MN) and the comet assay. BOT was not genotoxic in either cell line; it decreased the clastogenic effects of doxorubicin, H₂O₂, and benzo[a]pyrene. These results indicate that BOT may have potential as a therapeutic agent.

Nuclear DNA Damage and Repair in Normal Ovarian Cells Caused by Epothilone B

This study was designed to assess, whether a new chemotherapeutic microtubule inhibitor, Epothilone B (EpoB, Patupilone), can induce DNA damage in normal ovarian cells (MM14.Ov), and to evaluate if such damage could be repaired. The changes were compared with the effect of paclitaxel (PTX) commonly employed in the clinic. The alkaline comet assay technique and TUNEL assay were used. The kinetics of DNA damage formation and the level of apoptotic cells were determined after treatment with IC50 concentrations of EpoB and PTX. It was observed that PTX generated significantly higher apoptotic and genotoxic changes than EpoB. The peak was observed after 48 h of treatment when the DNA damage had a maximal level. The DNA damage induced by both tested drugs was almost completely repaired. As EpoB in normal cells causes less damage to DNA it might be a promising anticancer drug with potential for the treatment of ovarian tumors.

Lentinan mitigates therarubicin-induced myelosuppression by activating bone marrow-derived macrophages in an MAPK/NF-κB-dependent manner

Bone marrow (BM) suppression (also known as myelosuppression) is the most common and most severe side-effect of therarubicin (THP) and thereby limits the clinical application of this anticancer agent. Lentinan (LNT), a glucan extracted from dried shiitake mushrooms (Lentinula edodes), exhibits a variety of pharmacological activities. The objectives of the present study were to determine the effect of LNT on the myelosuppression of THP-treated mice and to examine the pharmacological mechanism of these effects. In vivo experiments indicated that non-cytotoxic levels of LNT strongly increased blood myeloperoxidase (MPO) activity; improved BM structural injuries; increased the numbers of leukocytes and neutrophils in the blood and BM; elevated the blood levels of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF); and reduced the self-healing period in THP-treated mice. In vitro experiments indicated that LNT increased the viability of BM-derived macrophages (BMDMs) in a time- and dose-dependent manner without toxic side-effects and markedly increased the release of G-CSF, GM-CSF and M-CSF by BMDMs. Further analyses revealed that LNT activated the NF-κB and MAPK signalling pathways and promoted the nuclear import of p65 and that BAY 11-7082 (a specific inhibitor of NF-κB) suppressed the release of G-CSF, GM-CSF and M-CSF. Furthermore, we found that U0126, SB203580 and SP600125 (specific inhibitors of ERK, p38 and JNK, respectively) markedly inhibited the IKK/IκB/NF-κB-dependent release of G-CSF, GM-CSF and M-CSF. In conclusion, LNT induces the production of G-CSF, GM-CSF and M-CSF by activating the MAPK/NF-κB signalling pathway in BM cells, thereby mitigating THP-induced myelosuppression.