Veliparib overcomes multidrug resistance in liver cancer cells

https://doi.org/10.1016/j.bbrc.2019.10.141Get rights and content

Highlights

  • Veliparib, a PARP1 and PARP2 inhibitor, significantly overcome MDR in liver cancer cells.

  • Veliparib inhibited the ATPase of ABCB1 transporter.

  • The combination of veliparib with conventional anticancer drugs could be a novel strategy to evade MDR in liver cancer cells.

Abstract

Overexpression of ATP-binding cassette (ABC) transporter is one of the most important factors taking responsibility for the progress of multidrug resistance (MDR) in multiple cancers. In this study, we investigated that veliparib, a PARP inhibitor which is in clinical development, could overcome ABCB1-mediated MDR in liver cancer cells. Veliparib could significantly enhance the cytotoxic effects of a series of conventional chemotherapeutic drugs in ABCB1-overexpression liver cancer cells. Mechanism study showed that veliparib could significantly enhance the accumulation of doxorubicin in ABCB1-overexpression liver cancer cells, without down-regulating the expression level of ABCB1. Finally, veliparib could significantly inhibit the ATPase activity of ABCB1 transporter. This study could provide information that combine veliparib with other chemotherapeutic drugs may benefit liver cancer patients.

Introduction

Liver cancer, the sixth most prevalent cancer all over the world, cause 0.6 million deaths per year [1]. A series of therapeutic strategies is available for liver cancer in clinic, for example, surgical resection or liver transplantation has been identified as valid approaches to liver cancer treatment. Moreover, local ablative therapy could recruit patients who loss surgical resection chance. Unfortunately, due to late diagnosis and/or advanced potential liver cirrhosis, liver cancer patients had to receive system chemotherapy [2]. On the other hand, intra-arterial delivery of chemotherapy agents, for example, transarterial chemoembolization (TACE), is also necessary when systemic chemotherapy is limited due to some severe side effects like systemic toxicity [3]. Therefore, chemotherapy is still one of a most crucial treatment modalities in the strategies of liver cancer therapy, especially for those patients with unresectable liver cancer [[3], [4], [5], [6], [7]]. However, the occurrence and development multidrug resistance (MDR) in cancer cells is a major obstacle in the treatment of liver cancer [8].

MDR is a phenomenon that lead cancer cells resistance to structurally and mechanically unrelated antineoplastic drugs [9]. Research carried out in decades has indicated that the mechanisms of MDR is mainly including apoptosis reduction, advanced DNA damage repair mechanisms, and/or the alteration of drug metabolism [10]. Nevertheless, one major mechanism contributing cancer cells resistance to anticancer drugs, especially chemotherapeutic drugs, is the overexpression the ABC (ATP-binding cassette) transporter on the membrane of cancer cells [11].

Expressing in both karyotes and eukaryotes, ABC transporters are large families that have 49 proteins and 48 of them have identified functions [12]. Structurally, the ABC transporters are constituted by transmembrane domains (TMDs) and nucleotide-binding domains (NBDs) [13]. The cavity in TMDs could combine a series of substrates by the energy from hydrolysis of ATP in NBDs. The ABC transporters are widely expressed in placenta, blood-brain barrier (BBB), intestines, livers and kidneys, and could transporter large number of endogenous substrates, including aliphatic acid, porphyrin, and sterol [14]. Meanwhile, some ABC transporter could also transport a series of anticancer drugs. ABCB1, for example, encoded by MDR1 gene, has high affinity to paclitaxel, doxorubicin, vincristine, and colchicine. These conventional chemotherapeutic drugs can be pumped out of the cancer cells by ABCB1, which will lead to down-regulation of intracellular concentration, as a result, MDR occurs [15]. It is documented that the overexpression of ABCB1 is contributed to chemoresistance in liver cancer [16]. Therefore, impeding the function of ABC transporter, especially the function of ABCB1 is a potential therapy strategy in liver cancer.

Veliparib, a PARP1 and PARP2 inhibitor in clinical development has shown potent anticancer effects on a panel of cancer cells [17]. However, there is hardly any research of veliparib on MDR reversal. Here we reported for the first time that veliparib have the capacity to overcome ABCB1-mediated MDR in liver cancer cells.

Section snippets

Chemicals

Veliparib was a product from Selleck (TX, USA), Dulbecco’s modified Eagle’s Medium (DMEM) and penicillin/streptomycin were purchased from Corning Incorporated (Corning, NY, USA), paclitaxel, doxorubicin, colchicine, fluorouracil, cisplatin and verapamil were purchased from MCE (Monmouth, NJ, USA). The monoclonal antibody of ABCB1 were purchased from Cell Signaling Technology (Danvers, MA, USA). HRP conjugated secondary goat anti mouse antibody was purchased from Beyotime Biotechnology

Veliparib significantly enhanced the sensitivity of anticancer drugs in drug-selected resistance cell lines

Firstly, to exclude the potential reversal effect caused by the cytotoxicity of veliparib, we conducted the MTT assays to choose relative non-toxic concentrations of veliparib for further experiments. As it is shown in Fig. 1A and B, over 80% of cells were survived after treated with less than 5 μM of veliparib, so we use 1 and 5 μM of veliparib for further reversal studies. To make sure that our resistant cells were overexpressing of ABCB1, we conducted our Western blot to verify. As shown in

Discussion

Though surgical resection has been considered the optimal treatment approach in liver cancer, only a small proportion of patients are suitable candidates for surgery, and the relapse rate is high [22]. Therefore, chemotherapy, including chemoembolization before and adjuvant therapy after surgery, is still a major approach in the treatment of hepatoma, especially in late stage of liver cancer patients. However, MDR, including acquired and/or congenital resistance to chemotherapeutic drug

Availability of data and materials

Not applicable.

Authors contribution

CL conceived the general idea. CL and HY performed experiments. CL, HY, ZL, and WZ analyzed the results. ZL, CG, SC, and LY wrote the first draft. CL and HY revised the manuscript.

Ethics approval and consent to participate

Not applicable.

Patient consent for publication

Not applicable.

Declaration of competing interest

The authors have declared no potential conflicts of interest.

Acknowledgements

This work was supported by Chongqing medical research program [grant numbers 2018QNXM042].

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    These authors contribute to this work equally.

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