Induction of multidrug resistance in MOLT-4 cells by anticancer agents is closely related to increased expression of functional P-glycoprotein and MDR1 mRNA

Overexpression of P-glycoprotein, encoded by the MDR1 (multidrug resistance 1) gene, is often responsible for multidrug resistance and chemotherapy failure in cancer. We have demonstrated that, in leukaemic cells, P-glycoprotein expression is regulated at the translational level. More recently, we have shown that in cells overexpressing P-glycoprotein, MDR1 mRNA does not aggregate into translationally silent stress granules. Importantly, this is not unique for MDR1, since other transcripts encoding transmembrane proteins, and which are thus translated at the endoplasmic reticulum, follow the same pattern. By using a series of chimaeric transcripts, we have demonstrated that transcript localization at the endoplasmic reticulum bypasses the signals dictating stress granule sequestration. Polysome profile analyses and protein synthesis experiments indicate that, upon stress withdrawal, endoplasmic-reticulum-bound transcripts resume translation faster than those at the cytosol, which have been sequestered into stress granules. This may represent a novel mechanism by which drug-resistant cells respond quickly to stress, helping them to survive the cytotoxic effect of chemotherapeutic drugs.

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Reversal of P-glycoprotein-medicated multidrug resistance by LBM-A5 in vitro and a study of its pharmacokinetics in vivo

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2014-0377 ◽

2015 ◽

Vol 93 (1) ◽

pp. 33-38 ◽

Cited By ~ 4

Author(s):

Tianxiao Zhao ◽

Yun Song ◽

Baomin Liu ◽

Qianqian Qiu ◽

Lei Jiao ◽

...

Keyword(s):

Multidrug Resistance ◽

Cancer Chemotherapy ◽

Anticancer Agents ◽

Efflux Pump ◽

Therapeutic Index ◽

Intracellular Accumulation ◽

P Glycoprotein ◽

Reversal Mechanism

The overexpression of P-glycoprotein (P-gp) in tumors leads to multidrug resistance (MDR), which is a significant obstacle in clinical cancer chemotherapy. The co-administration of anticancer drugs and MDR modulators is a promising strategy for overcoming this problem. Our study aimed to explore the reversal mechanism and safety of the MDR modulator LBM-A5 in vitro, and evaluate its pharmacokinetics and effects on doxorubicin metabolism in vivo. We evaluated an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay of anticancer agents mediated by LBM-A5, the effect of LBM-A5 on rhodamine123 intracellular accumulation, and the efflux in K562/DOX cells to investigate the reversal mechanisms of LBM-A5. The results showed that LBM-A5 inhibits rhodamine123 efflux and increases intracellular accumulation by inhibiting the efflux pump function of P-gp. Furthermore, the therapeutic index and CYP3A4 activity analysis in vitro suggested that LBM-A5 is reasonably safe to use. Also, LBM-A5 (10 mg/kg body mass) achieved the required plasma concentration in sufficient time to reverse MDR in vivo. Importantly, the LBM-A5 treatment group shared similar doxorubicin (DOX) pharmacokinetics with the free DOX group. Our results suggest that LBM-A5 effectively reverses MDR (EC50 = 483.6 ± 81.7 nmol·L−1) by inhibiting the function of P-gp, with relatively ideal pharmacokinetics and in a safe manner, and so may be a promising candidate for cancer chemotherapy research.

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Role of the highly structured 5′-end region of MDR1 mRNA in P-glycoprotein expression

Biochemical Journal ◽

10.1042/bj20070235 ◽

2007 ◽

Vol 406 (3) ◽

pp. 445-455 ◽

Cited By ~ 20

Author(s):

Rebecca A. Randle ◽

Selina Raguz ◽

Christopher F. Higgins ◽

Ernesto Yagüe

Keyword(s):

Multidrug Resistance ◽

Drug Exposure ◽

Cytotoxic Drugs ◽

Initiation Factor ◽

Mrna Levels ◽

Translational Repressor ◽

P Glycoprotein ◽

Mdr1 Mrna ◽

Cytotoxic Stress

Overexpression of P-glycoprotein, encoded by the MDR1 (multidrug resistance 1) gene, is often responsible for multidrug resistance in acute myeloid leukaemia. We have shown previously that MDR1 (P-glycoprotein) mRNA levels in K562 leukaemic cells exposed to cytotoxic drugs are up-regulated but P-glycoprotein expression is translationally blocked. In the present study we show that cytotoxic drugs down-regulate the Akt signalling pathway, leading to hypophosphorylation of the translational repressor 4E-BP [eIF (eukaryotic initiation factor) 4E-binding protein] and decreased eIF4E availability. The 5′-end of MDR1 mRNA adopts a highly-structured fold. Fusion of this structured 5′-region upstream of a reporter gene impeded its efficient translation, specifically under cytotoxic stress, by reducing its competitive ability for the translational machinery. The effect of cytotoxic stress could be mimicked in vivo by blocking the phosphorylation of 4E-BP by mTOR (mammalian target of rapamycin) using rapamycin or eIF4E siRNA (small interfering RNA), and relieved by overexpression of either eIF4E or constitutively-active Akt. Upon drug exposure MDR1 mRNA was up-regulated, apparently stochastically, in a small proportion of cells. Only in these cells could MDR1 mRNA compete successfully for the reduced amounts of eIF4E and translate P-glycoprotein. Consequent drug efflux and restoration of eIF4E availability results in a feed-forward relief from stress-induced translational repression and to the acquisition of drug resistance.

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Multidrug resistance in tumour cells: characterisation of the multidrug resistant cell line K562-Lucena 1

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652001000100007 ◽

2001 ◽

Vol 73 (1) ◽

pp. 57-69 ◽

Cited By ~ 69

Author(s):

VIVIAN M. RUMJANEK ◽

GILMA S. TRINDADE ◽

KAREN WAGNER-SOUZA ◽

MICHELE C. MELETTI-DE-OLIVEIRA ◽

LUIS F. MARQUES-SANTOS ◽

...

Keyword(s):

Multidrug Resistance ◽

Cell Line ◽

Anticancer Agents ◽

Vinca Alkaloid ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Resistant Cell ◽

Cross Reactivity ◽

Resistant Cell Line ◽

P Glycoprotein

Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed.

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Development of a Novel Quinoline Derivative as a P-Glycoprotein Inhibitor to Reverse Multidrug Resistance in Cancer Cells

Biology ◽

10.3390/biology8040075 ◽

2019 ◽

Vol 8 (4) ◽

pp. 75 ◽

Cited By ~ 1

Author(s):

Yuanyuan Zhou ◽

Po-yee Chung ◽

Jessica Yuen-wuen Ma ◽

Alfred King-yin Lam ◽

Simon Law ◽

...

Keyword(s):

Multidrug Resistance ◽

Cancer Cells ◽

Cell Lines ◽

Anticancer Agents ◽

Underlying Mechanism ◽

Quinoline Derivative ◽

Parental Cancer ◽

Reversal Effect ◽

P Glycoprotein ◽

Mdr Reversal

Multidrug resistance (MDR) is one of conventional cancer chemotherapy’s limitations. Our group previously synthesized a series of quinoline-based compounds in an attempt to identify novel anticancer agents. With a molecular docking analysis, the novel compound 160a was predicted to target p-glycoprotein, an MDR candidate. The purpose of this study is to evaluate 160a’s MDR reversal effect and investigate the underlying mechanism at the molecular level. To investigate 160a’s inhibitory effect, we used a series of parental cancer cell lines (A549, LCC6, KYSE150, and MCF-7), the corresponding doxorubicin-resistant cell lines, an MTS cytotoxicity assay, an intracellular doxorubicin accumulation test, and multidrug resistance assays. The Compusyn program confirmed, with a combination index (CI) value greater than 1, that 160a combined with doxorubicin exerts a synergistic effect. Intracellular doxorubicin accumulation and transported calcein acetoxymethyl (AM) (a substrate for p-glycoprotein) were both increased when cancer cells with MDR were treated with compound 160a. We also showed that compound 160a’s MDR reversal effect can persist for at least 1 h. Taken together, these results suggest that the quinoline compound 160a possesses high potential to reverse MDR by inhibiting p-glycoprotein-mediated drug efflux in cancer cells with MDR.

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