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    Home > Active Ingredient News > Antitumor Therapy > STTT Shandong University Lou Hongxiang/Yuan Huiqing discovers potential therapeutic targets for multidrug resistance

    STTT Shandong University Lou Hongxiang/Yuan Huiqing discovers potential therapeutic targets for multidrug resistance

    • Last Update: 2021-06-17
    • Source: Internet
    • Author: User
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    Editor’s note iNature is China’s largest academic official account.
    It is jointly created by the doctoral team of Tsinghua University, Harvard University, Chinese Academy of Sciences and other units.
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    .

    iNature Multidrug Resistance (MDR) remains a major challenge for successful cancer treatment
    .

    Many mechanisms that confer treatment-induced resistance have been extensively studied to explore how to combat MDR
    .

    In this regard, lysosomal sequestration has been shown to be a mechanism that leads to drug resistance through an "off-target" effect, in which hydrophobic and weakly alkaline chemotherapeutics are trapped in the lysosome, isolating them from the target
    .

    Methods to disrupt lysosomal acidification, regulate acid sphingomyelinase (ASM) and increase lysosomal membrane permeability have been developed to overcome drug resistance
    .

    On June 7, 2021, Hongxiang Lou and Huiqing Yuan of Shandong University jointly published an online report entitled "Targeting of VPS18 by the lysosomotropic agent RDN reverses TFE3-mediated drug resistance" on Signal Transduction and Targeted Therapy (IF=13.
    49).
    Research paper, this study proved the new function of TFE3/lysosome/MRP2 in the development of MDR through the lysosomal isolation mechanism
    .

    The contribution of lysosomal VPS18 to the development of cancer and drug resistance can be explored as a potential therapeutic target.
    It is specifically inhibited by a new compound RDN to treat acquired drug-resistant cancer
    .

    Multidrug resistance (MDR) remains a major challenge for successful cancer treatment
    .

    Many mechanisms that confer treatment-induced resistance have been extensively studied to explore how to combat MDR
    .

    In this regard, lysosomal isolation has been shown to be a mechanism that leads to drug resistance through an "off-target" effect, in which hydrophobic and weakly alkaline chemotherapeutics are trapped in the lysosome, isolating them from the target
    .

    Methods to disrupt lysosomal acidification, regulate acid sphingomyelinase (ASM) and increase lysosomal membrane permeability have been developed to overcome drug resistance
    .

     Transcription factor E3 (TFE3) and TFEB become the main regulators of lysosomal biogenesis and autophagy in response to cellular stress.
    Therefore, interruption of TFE3/TFEB-mediated effects has great therapeutic potential in cancer
    .

    In this study, a new mechanism was revealed by which TFE3/lysosomes activate the response to therapeutic agents, such as docetaxel (Doc), by promoting the dissolution of multidrug resistance-related protein 2 (MRP2).
    Enzyme positioning and enhancing drug sequestration in the lysosome to promote MDR.
    The study also identified lysosomal vacuolar protein sorting 18 (VPS18) as a new type of lysosomal drug RDN (a natural double benzyl riccardin).
    D's aminomethylated derivatives) are potential targets for the reversal of chemoresistance
    .

    The study initially evaluated the changes in gene expression in Doc-induced multidrug resistance PC3/Doc cancer cells
    .

    The expression profile of genes related to lysosomal and mitochondrial pathway metabolism is particularly altered in resistant cells
    .

    The examination of lysosome-related parameters showed that the number of lysosomes and autophagosomes increased significantly in different resistant cell lines
    .

    Therefore, lysosomal activation is the result of different anti-tumor drug treatments
    .

    Given the importance of TFEB and TFE3 in regulating lysosomal biogenesis, this study determined the involvement of these two factors in the treatment-induced metabolic transformation to lysosomes
    .

    The results clearly show that clinical drugs significantly activate TFEB and TFE3, especially TFE3, and promote TFE3 nuclear translocation (a highly phosphorylated active form) in vitro and in vivo
    .

    Next, it was determined whether the treatment-activated TFE3/lysosome contributes to resistance
    .

    Down-regulation of TFE3 significantly restored the sensitivity of PC3/Doc cells to Doc or Dox, while overexpression of TFE3 significantly increased the tolerance of PC3 cells to drugs, indicating the role of TFE3 in conferring MDR
    .

    Therefore, lysosomal-mediated capture of Doc or Dox can cause off-target effects, thereby reducing its anti-tumor efficacy
    .

    To explore the underlying mechanism of lysosomal drug sequestration, this study tested whether the ABC family of transporters act as cell membrane pumps and play a key role in mediating MDR
    .

    The screening assay identified MRP2 (ABCC2) as an important mediator of lysosomal resistance
    .

    Although MRP2 is mainly located on the cell membrane, a large amount of MRP2 is present in the cytoplasm and appears to be colocalized with lysosomal-associated membrane protein 2 (LAMP2) in resistant cells
    .

    Further studies have determined that MRP2 is the target of TFE3, which can enhance the expression of MRP2 through the transcription of the E-box motif in the MRP2 promoter after chemical treatment
    .

    Therefore, treatment-driven activation of TFE3 stimulates the expression and localization of MRP2 in lysosomes, and promotes lysosomal-mediated drug capture and drug resistance
    .

    Schematic diagram of the article (picture from STTT) The study next determined whether targeting the TFE3/lysosome axis is effective in reversing MDR
    .

    The results indicate that RDN binds to the RING domain of VPS18, leading to the destruction of the VPS-C core complex and lysosome function
    .

    In order to explore whether VPS18 is an important pathological effector, the study first detected the level of VPS18 in cancer
    .

    The results showed that the expression of VPS18 in several cancers was higher than that of adjacent non-cancerous tissues, including prostate cancer (PRAD), bladder cancer (BLCA), liver cancer (LIHC) and lung cancer (LUAD)
    .

    High levels of VPS18 are associated with poor prognosis of malignant cancer
    .

    VPS18 knockdown significantly inhibited cancer cell proliferation and tumor growth in mice
    .

    Importantly, the study observed that VPS18 expression can be induced by different chemotherapeutic drugs and increased significantly in drug-resistant cells
    .

    VPS18 silencing significantly increased the sensitivity of drug-resistant cells to Doc and Dox, while overexpression of VPS18 inhibited the effect of chemotherapy drugs on cell proliferation
    .

    Therefore, VPS18 has become a new molecular indicator of tumor prognosis and a target for reversing lysosomal-mediated drug resistance
    .

    In conclusion, the evidence provided by this study proves the new function of TFE3/lysosome/MRP2 in the development of MDR through the lysosomal sequestration mechanism
    .

    The contribution of lysosomal VPS18 to the development of cancer and drug resistance can be explored as a potential therapeutic target.
    It is specifically inhibited by a new compound RDN to treat acquired drug-resistant cancer
    .

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