Abstract
Glioblastoma is the most common malignant primary brain tumor, and it is one of the causes of cancer fatality in both adult and pediatric populations. Patients with glioblastoma require chemotherapy after surgical resection and radiotherapy. Therefore, chemotherapy constitutes a viable approach for the eradication of glioblastoma cells. In this study, the anti-tumor activity of sinomenine hydrochloride (SH) was evaluated in U87 and SF767 cells in vitro and in vivo. The results showed that SH potently inhibited U87 and SF767 cell viability and did not cause caspase-dependent cell death, as demonstrated by the absence of significant early apoptosis and caspase-3 cleavage. Instead, SH activated an autophagy-mediated cell death pathway, as indicated by the accumulated microtubule-associated protein light chain 3B (LC3B)-II, triggered autophagic flux and enhanced cell viability after pretreatment with autophagy inhibitors. SH-mediated autophagy in the two cell lines was implicated in reactive oxygen species (ROS) generation, protein kinase B (Akt)-mammalian target of rapamycin (mTOR) pathway suppression and c-Jun NH2-terminal kinase (JNK) pathway activation. The ROS antioxidant N-acetylcysteine (NAC), the Akt-specific activator insulin-like growth factor-1 (IGF-1) and the JNK-specific inhibitor SP600125 attenuated SH-induced autophagy. Moreover, ROS activated autophagy via the Akt-mTOR and JNK pathways. Additionally, SH treatment may promote lysosome biogenesis through activating transcription factor EB (TFEB). The in vivo study found that SH effectively suppressed glioblastoma growth without exhibiting significant toxicity. In conclusion, our findings reveal a novel mechanism of action of SH in cancer cells via the induction of autophagy through ROS generation and autophagy-lysosome pathway activation; these findings also supply a new potential therapeutic agent for the treatment of human glioblastoma.
Highlights
Glioblastoma is one of the most aggressive and malignant brain tumors in the central nervous system, and conventional cancer therapies have failed to exert positive effects on human glioblastoma [1,2]
Our study revealed that sinomenine hydrochloride (SH) could suppress U87 and SF767 cell proliferation in vitro and in vivo
Autophagy might be employed as a therapeutic target only if it can be strongly activated in cancer cells
Summary
Glioblastoma is one of the most aggressive and malignant brain tumors in the central nervous system, and conventional cancer therapies have failed to exert positive effects on human glioblastoma [1,2]. Previous research has demonstrated that the major signaling molecule regulating lysosomal biogenesis is TFEB, a basic helix-loop-helix leucine zipper transcription factor [32], and mTOR inhibitors, such as PP242 and torin, are currently primarily regarded as activators of TFEB, by means of triggering its nuclear translocation [33,34] Based on these observations, we hypothesized that SH suppresses human glioblastoma cell growth by regulating these signaling pathways. Our results reveal an innovative mechanism of action of SH in triggering autophagy, but not apoptosis, in both human glioblastoma cells through ROS generation and autophagy-lysosome pathway activation. During the treatments, no behavioral abnormalities were found, and no Similar results were obtained, compared with the in vitro experiments (Figure 7F) These findings revInet.aJl.eMdolt.hScai.t2S0H17,i1n8i, t1i9a4t5ed the autophagy-lysosome pathway in both in vitro and in vivo exp1e2riomf 2e2nts. FiFgiugruere7.7.SSHHssuupppprreesssseess tthheeggrorowwththofohf uhmumanagnligolbiloabsltaosmtoamtuamtourms ionrsviivnov. i(vAo).B(oAd)yBwoedigyhwt aenigdh(tBa) nd (Bt)utmumorovrovluolmuemwe ewreerreecreocrdoreddeedveevryer2y–32–d3adysa;y(sC; )(CIm) Iamgeasgeosf otufmtuomrsoarrseasrheoswhonw; (nD; )(DTu) mTuomr worewigheitght wawsaassassessessesdedononththeefiffitfeteeenntthhddaayyaafftteerr UU87 cell immppllaannttaattioionn. .(E(E) )ImImmmunuonhoihstiosctohcehmeimcailcsatlasintaininginogf of clecalevaevdedcascpaaspsea-s3e,-L3,C3LBC,3pB6,2,pc6a2t,hecpatshinepBsianndBcaatnhdepscianthDepinsintumDorinsectutimonosr trseeacteiodnws ithrepatheydsiowloitghical saplihnyesoiorlSoHgic(a1l5s0amlinge/okrgS).HT(h1e50pamnge/lksga)r.eTrheeppreasneenlstaatrive ereopvreersveinetwatiivmeaogveesrvtaiekwenimata4g0e0s×tamkeangantifi40c0a×tion, wimthagtnhieficeaxtcioenp,tiownitohf ththee imexmceupntoiohnistocf hethmeicaiml smtauinnoinhgistoofchLeCm3iBcal(10s0ta0i×ninmgagonfifiLcCat3iBon)(;1(0F0)0×The inmdiacganteifdicaptrionte)i;n(Fs)fTrohme intrdaicnastpeldanptreodteimnsofurosemUtr8a7nshpulamnatendgmliooubsleasUto8m7 hautmisasnuegsliowbelarsetoemxaamtiisnseudesvia Wweseterernexbalmotitninegd.vβia-aWcteinstweransbulostetdinags. βth-aecltoinadwiansgucsoendtraoslt.hDealotaadairnegrecponretrsoeln.tDedatasatrheerempreeasnen±teSdEaMs of setvheenmmeiacne ±inSeEaMchogfrsoeuvpen. *mpic
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