Ibrutinib, a Bruton’s tyrosine kinase inhibitor, exhibits antitumoral activity and induces autophagy in glioblastoma

Abstract

BackgroundGlioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor, is a novel anticancer drug used for treating several types of cancers. In this study, we aimed to determine the role of ibrutinib on GBM.MethodsCell proliferation was determined by using cell viability, colony formation, and 5-ethynyl-2′-deoxyuridine (EdU) assays. Cell cycle and cell apoptosis were analyzed by flow cytometry. Cell migratory ability was evaluated by wound healing assays and trans-well migration assays. ATG7 expression was knocked-down by transfection with Atg7-specific small interfering RNA. Overexpression of active Akt protein was achieved by transfecting the cells with a plasmid expressing constitutively active Akt (CA-Akt). Transmission electron microscopy was performed to examine the formation of autophagosomes in cells. Immunofluorescence and western blot analyses were used to analyze protein expression. Tumor xenografts in nude mice and immunohistochemistry were performed to evaluate the effect of ibrutinib on tumor growth in vivo.ResultsIbrutinib inhibited cellular proliferation and migration, and induced apoptosis and autophagy in LN229 and U87 cells. Overexpression of the active Akt protein decreased ibrutinib-induced autophagy, while inhibiting Akt by LY294002 treatment enhanced ibrutinib-induced autophagy. Specific inhibition of autophagy by 3-methyladenine (3MA) or Atg7 targeting with small interfering RNA (si-Atg7) enhanced the anti-GBM effect of ibrutinib in vitro and in vivo.ConclusionsOur results indicate that ibrutinib exerts a profound antitumor effect and induces autophagy through Akt/mTOR signaling pathway in GBM cells. Autophagy inhibition promotes the antitumor activity of ibrutinib in GBM. Our findings provide important insights into the action of an anticancer agent combining with autophagy inhibitor for malignant glioma.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-017-0549-6) contains supplementary material, which is available to authorized users.

TSSC3 promotes autophagy via inactivating the Src-mediated PI3K/Akt/mTOR pathway to suppress tumorigenesis and metastasis in osteosarcoma, and predicts a favorable prognosis

“…As a member of phosphatidylinositol 3-kinase-related kinases (PIKKs), mTOR is one of the key regulators of mammalian cell metabolism and is the main downstream target of the PI3K/Akt signaling pathway [ 52 ]. Numerous reports have highlighted the importance of mTOR and its downstream target p70S6K in regulating autophagy [ 26 , 27 ]. Previously, we reported that TSSC3 interacts with RanBP9 bound to Src to prevent its phosphorylation, which further abrogated Src-dependent Akt pathway activation [ 10 ].…”

“…More recently, PHLDA1 , the homologous gene of TSSC3 has been demonstrated to trigger autophagy [ 25 ]. Moreover, the PI3K/Akt/mTOR signaling pathway, which is a classical pathway that modulates cell proliferation, apoptosis resistance, and tumorigenesis, is reported to be involved in the regulation of autophagy in several human tumors cells [ 26 , 27 ] and can be activated by the Src-family kinases [ 28 ]. Our previous studies found that TSSC3 could inhibit the phosphorylation of both Src and Akt in osteosarcoma cells [ 10 , 11 ]; therefore, we speculated that autophagy might be involved in the anti-tumor effect of TSSC3.…”

Novel Indications for Bruton’s Tyrosine Kinase Inhibitors, beyond Hematological Malignancies

“…BTK also appeared to be required for EGFR-induced NF-κB activation in glioma cells. Another study has described an antitumor effect that induces autophagy through AKT/mTOR signaling pathway in GBM cells [ 50 ]. In xenograft mouse models, tumorigenesis was significantly reduced in BTK silenced or ibrutinib-treated mice compared to controls [ 49 ].…”

Ibrutinib suppresses intracellular mycobacterium tuberculosis growth by inducing macrophage autophagy

“…4 , 11 The kinase PKC β lying downstream of BTK signaling has been reported as an essential regulator of AKT/mTOR signaling, 14 previous report has shown that inhibition of BTK by ibrutinib, which has been approved as firstline drug to treat chronic lymphocytic leukemia (CLL), significantly enhanced autophagy in cancer cell line glioblastoma through suppression of Akt/mTOR pathway. 15 Notably, administration of ibrutinib to treat CLL was reported in association with lower rates of infections compared to the standard chemo-immunotherapy (such as Fludarabine, Cyclophosphamide, Rituximab). 16 Although it is currently unknown whether and how such effect of ibrutinib is associated with its bystand effect in enhancing autophagy, these findings prompt us to hypothesize that ibrutinib might be an HDT candidate against Mtb through enhancing macrophage autophagy.…”