In vitro, in vivo and ex vivo characterization of ibrutinib: a potent inhibitor of the efflux function of the transporter MRP1

Abstract

BACKGROUND AND PURPOSEThe transporter, multidrug resistance protein 1 (MRP1, ABCC1), plays a critical role in the development of multidrug resistance (MDR). Ibrutinib is an inhibitor of Bruton's tyrosine kinase. Here we investigated the reversal effect of ibrutinib on MRP1-mediated MDR. EXPERIMENTAL APPROACHCytotoxicity was determined by MTT assay. The expression of protein was detected by Western blot. RT-PCR and Q-PCR were performed to detect the expression of MRP1 mRNA. The intracellular accumulation and efflux of substrates for MRP1 were measured by scintillation counter and flow cytometry. HEK293/MRP1 cell xenografts in nude mice were established to study the effects of ibrutinib in vivo. KEY RESULTSIbrutinib significantly enhanced the cytotoxicity of MRP1 substrates in HEK293/MRP1 and HL60/Adr cells overexpressing MRP1. Furthermore, ibrutinib increased the accumulation of substrates in these MRP1-overexpressing cells by inhibiting the drug efflux function of MRP1. However, mRNA and protein expression of MRP1 remained unaltered after treatment with ibrutinib in MRP1-overexpressing cells. In vivo, ibrutinib enhanced the efficacy of vincristine to inhibit the growth of HEK293/MRP1 tumour xenografts in nude mice. Importantly, ibrutinib also enhances the cytotoxicity of vincristine in primary cultures of leukaemia blasts, derived from patients. CONCLUSIONS AND IMPLICATIONSOur results indicated that ibrutinib significantly increased the efficacy of the chemotherapeutic agents which were MRP1 substrates, in MRP1-overexpressing cells, in vitro, in vivo and ex vivo. These findings will lead to further studies on the effects of a combination of ibrutinib with chemotherapeutic agents in cancer patients overexpressing MRP1. AbbreviationsABC, ATP-binding cassette; BTK, Bruton's tyrosine kinase; MDR, multidrug resistance; MRP1, multidrug resistance protein 1

Multidrug Resistance Proteins (MRPs) and Cancer Therapy

“…It has been found that ibrutinib (1 and 5 μM) could significantly sensitize HL60/Adr leukemia cells and transfected HEK293/MRP1 to the substrates of MRP1. This reversal activity of ibrutinib was stronger than that of MK-571 as positive control (11). It was also reported that ibrutinib potently blocked the efflux of showed a great inhibitory effect on the tumor growth, as compared to mice administered with vehicle, vincristine, or ibrutinib alone.…”

“…It was also reported that ibrutinib potently blocked the efflux of showed a great inhibitory effect on the tumor growth, as compared to mice administered with vehicle, vincristine, or ibrutinib alone. Also, there were no significant visible toxicities or phenotypic changes between different treatment groups (11). Moreover, ibrutinib (5 μM) can strengthen the effect of vincristine to the leukemia blast cells in three patient samples, which exhibited detectable levels of MRP1 expression (11).…”

“…Also, there were no significant visible toxicities or phenotypic changes between different treatment groups (11). Moreover, ibrutinib (5 μM) can strengthen the effect of vincristine to the leukemia blast cells in three patient samples, which exhibited detectable levels of MRP1 expression (11). Collectively, ibrutinib could increase the antitumor activity of MRP1 substrate anticancer drugs in MRP1 overexpressing cells in vitro, in vivo, and ex vivo.…”

Elevated Glutathione Is Not Sufficient to Protect against Doxorubicin-Induced Nuclear Damage in Heart in Multidrug Resistance–Associated Protein 1 (Mrp1/Abcc1) Null Mice

“…These data also suggest that Mrp1 has additional functions other than efflux of these known substrates, and whose loss contributes to toxicity. Thus, the development of MRP1 inhibitors in the treatment of cancer Zhang et al, 2014) may have unanticipated toxicities, including cardiotoxicity.…”

PCI29732, a Bruton’s Tyrosine Kinase Inhibitor, Enhanced the Efficacy of Conventional Chemotherapeutic Agents in ABCG2-Overexpressing Cancer Cells

“…It has been identified as an essential signaling kinase for cell survival of a subtype of diffuse large B-cell lymphoma [21]. Recently, PCI32765 (Ibrutinib), a novel BTK inhibitor, was approved by the United States Food and Drug Administration (FDA) for treating patients with mantle cell lymphoma (MCL) [22], and it has recently been shown by many in vitro, in vivo, and ex vivo cancer models that it can increase the effectiveness of several chemotherapeutic agents that are ABCC1/MRP1 substrates in MRP1-overexpressing cells [23].…”