Dacomitinib antagonizes multidrug resistance (MDR) in cancer cells by inhibiting the efflux activity of ABCB1 and ABCG2 transporters

In vitro models to evaluate multidrug resistance in cancer cells: Biochemical and morphological techniques and pharmacological strategies

The overexpression of ATP-binding cassette (ABC) transporters contributes to the failure of chemotherapies and symbolizes a great challenge in oncology, associated with the adaptation of tumor cells to anticancer drugs such that these transporters become less effective, a mechanism known as multidrug resistance (MDR). The aim of this review is to present the most widely used methodologies for induction and comprehension of in vitro models for detection of multidrug-resistant (MDR) modulators or inhibitors, including biochemical and morphological techniques for chemosensitivity studies. The overexpression of MDR proteins, predominantly, the subfamily glycoprotein-1 (P-gp or ABCB1) multidrug resistance, multidrug resistance-associated protein 1 (MRP1 or ABCCC1), multidrug resistance-associated protein 2 (MRP2 or ABCC2) and cancer resistance protein (ABCG2), in chemotherapy-exposed cancer lines have been established/investigated by several techniques. Amongst these techniques, the most used are (i) colorimetric/fluorescent indirect bioassays, (ii) rhodamine and efflux analysis, (iii) release of 3,30-diethyloxacarbocyanine iodide by fluorescence microscopy and flow cytometry to measure P-gp function and other ABC transporters, (iv) exclusion of calcein-acetoxymethylester, (v) ATPase assays to distinguish types of interaction with ABC transporters, (vi) morphology to detail phenotypic characteristics in transformed cells, (vii) molecular testing of resistance-related proteins (RT-qPCR) and (viii) 2D and 3D models, (ix) organoids, and (x) microfluidic technology. Then, in vitro models for detecting chemotherapy MDR cells to assess innovative therapies to modulate or inhibit tumor cell growth and overcome clinical resistance. It is noteworthy that different therapies including anti-miRNAs, antibody-drug conjugates (to natural products), and epigenetic modifications were also considered as promising alternatives, since currently no anti-MDR therapies are able to improve patient quality of life. Therefore, there is also urgency for new clinical markers of resistance to more reliably reflect in vivo effectiveness of novel antitumor drugs.

Mobocertinib antagonizes multidrug resistance in ABCB1- and ABCG2-overexpressing cancer cells: In vitro and in vivo studies

Overexpression of ATP-binding cassette (ABC) transporters, particularly ABCB1 and ABCG2, strongly correlates with multidrug resistance (MDR), rendering cancer chemotherapy ineffective. Exploration and identification of novel inhibitors targeting ABCB1 and ABCG2 are necessary to overcome the related MDR. Mobocertinib is an approved EGFR/HER2 inhibitor for non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion mutations. This study demonstrates that mobocertinib can potentially reverse ABCB1- and ABCG2-mediated MDR. Our findings indicate a strong interaction between mobocertinib and these two proteins, supported by its high binding affinity with ABCB1 and ABCG2 models. Through inhibiting the drug efflux function of ABCB1 and ABCG2, mobocertinib facilitates substrate drugs accumulation, thereby re-sensitizing substrate drugs in drug-resistant cancer cells. Additionally, mobocertinib inhibited the ATPase activity of ABCB1 and ABCG2 without changing the expression levels or subcellular localization. In the tumor-bearing mouse model, mobocertinib boosted the antitumor effect of paclitaxel and topotecan, resulting in tumor regression. In summary, our study uncovers a novel potential for repurposing mobocertinib as a dual inhibitor of ABCB1 and ABCG2, and suggests the combination of mobocertinib with substrate drugs as a strategy to counteract MDR.

Explorations of novel MDR-related hub genes and the potential roles TRIM9 played in drug-resistant hepatocellular carcinoma

Current chemotherapeutic efficacy is limited by the rapid development of multidrug resistance (MDR) in hepatocellular carcinoma (HCC). In this study, 66 MDR-related hub genes in drug-resistant HCC were identified through combined analysis of differential expressed genes (DEGs), gene functional enrichment, Cox proportional regression, weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) network construction. A prognostic risk model was established through the LASSO-Cox regression analysis. Based on the comparison of gene mutation frequency, tumor mutation burden (TMB) and immune infiltration in high- and low-risk groups, we explored the relationships between the MDR-related hub genes and immune regulation. The competitive endogenous RNA (ceRNA) network and associated non-coding RNAs (ncRNAs) were predicted to investigate the potential mechanisms. Five MDR-related hub genes in drug-resistant HCC were finally confirmed, namely ABCB6, FLNC, MCC, NAV3 and TRIM9. TRIM9 was identified as the most significant gene enhancing MDR. Inhibiting TRIM9 caused a decrease in the IC50 of doxorubicin (DOX), and significant increases in the intracellular uptake, retention and absorption of DOX in HepG2/ADR cells. These findings may provide new insights into the mechanism of MDR development. The MDR-related hub genes, especially TRIM9 may be targeted therapeutically to enhance the prognosis of patients with drug-resistant HCC.

Marein, a novel natural product for restoring chemo-sensitivity to cancer cells through competitive inhibition of ABCG2 function

The pivotal roles of ATP-binding cassette (ABC) transporters in drug resistance have been widely appreciated. Here we report that marein, a natural product from Coreopsis tinctoria Nutt, is a potent chemo-sensitizer in drug resistant cancer cells overexpressing ABCG2 transporter. We demonstrate that marein can competitively inhibit efflux activity of ABCG2 protein and increase the intracellular accumulation of the chemotherapeutic drugs that belong to substrate of this transporter. We further show that marein can bind to the conserved amino acid residue F439 of ABCG2, a critical site for drug-substrate interaction. Moreover, marein can significantly sensitize the ABCG2-expressing tumor cells to chemotherapeutic drugs such as topotecan, mitoxantrone, and olaparib. This study reveals a novel role and mechanism of marein in modulating drug resistance, and may have important implications in treatment of cancers that are resistant to chemotherapeutic drugs that belong to the substrates of ABCG2 transporters.

Graphene Quantum Dots Eradicate Resistant and Metastatic Cancer Cells by Enhanced Interfacial Inhibition

Drug-resistant and metastatic cancer cells such as a small population of cancer stem cells (CSCs) play a crucial role in metastasis and relapse. Conventional small-molecule chemotherapeutics, however, are unable to eradicate drug-resistant CSCs owing to limited interface inhibitory effects. Herein, it is reported that enhanced interfacial inhibition leading to eradication of drug-resistant CSCs can be dramatically induced by self-insertion of bioactive graphene quantum dots (GQDs) into DNA major groove (MAG) sites in cancer cells. Since transcription factors regulate gene expression at the MAG site, MAG-targeted GQDs exert greatly enhanced interfacial inhibition, downregulating the expression of a collection of cancer stem genes such as ALDH1, Notch1, and Bmi1. Moreover, the nanoscale interface inhibition mechanism reverses cancer multidrug resistance (MDR) by inhibiting MDR1 gene expression when GQDs are used at a nontoxic concentration (1/4 × half-maximal inhibitory concentration (IC50)) as the MDR reverser. Given their high efficacy in interfacial inhibition, CSC-mediated migration, invasion, and metastasis of cancer cells can be substantially blocked by MAG-targeted GQDs, which can also be harnessed to sensitize clinical cytotoxic agents for improved efficacy in combination chemotherapy. These findings elucidate the inhibitory effects of the enhanced nano-bio interface at the MAG site on eradicating CSCs, thus preventing cancer metastasis and recurrence.

BI-2865, a pan-KRAS inhibitor, reverses the P-glycoprotein induced multidrug resistance in vitro and in vivo

BACKGROUND

Multidrug resistance (MDR) limits successful cancer chemotherapy. P-glycoprotein (P-gp), BCRP and MRP1 are the key triggers of MDR. Unfortunately, no MDR modulator was approved by FDA to date. Here, we will investigate the effect of BI-2865, a pan-KRAS inhibitor, on reversing MDR induced by P-gp, BCRP and MRP1 in vitro and in vivo, and its reversal mechanisms will be explored.

METHODS

The cytotoxicity of BI-2865 and its MDR removal effect in vitro were tested by MTT assays, and the corresponding reversal function in vivo was assessed through the P-gp mediated KBv200 xenografts in mice. BI-2865 induced alterations of drug discharge and reservation in cells were estimated by experiments of Flow cytometry with fluorescent doxorubicin, and the chemo-drug accumulation in xenografts' tumor were analyzed through LC-MS. Mechanisms of BI-2865 inhibiting P-gp substrate's efflux were analyzed through the vanadate-sensitive ATPase assay, [125I]-IAAP-photolabeling assay and computer molecular docking. The effects of BI-2865 on P-gp expression and KRAS-downstream signaling were detected via Western blotting, Flow cytometry and/or qRT-PCR. Subcellular localization of P-gp was visualized by Immunofluorescence.

RESULTS

We found BI-2865 notably fortified response of P-gp-driven MDR cancer cells to the administration of chemo-drugs including paclitaxel, vincristine and doxorubicin, while such an effect was not observed in their parental sensitive cells and BCRP or MRP1-driven MDR cells. Importantly, the mice vivo combination study has verified that BI-2865 effectively improved the anti-tumor action of paclitaxel without toxic injury. In mechanism, BI-2865 prompted doxorubicin accumulating in carcinoma cells by directly blocking the efflux function of P-gp, which more specifically, was achieved by BI-2865 competitively binding to the drug-binding sites of P-gp. What's more, at the effective MDR reversal concentrations, BI-2865 neither varied the expression and location of P-gp nor reduced its downstream AKT or ERK1/2 signaling activity.

CONCLUSIONS

This study uncovered a new application of BI-2865 as a MDR modulator, which might be used to effectively, safely and specifically improve chemotherapeutic efficacy in the clinical P-gp mediated MDR refractory cancers.

Overexpression of ABCC1 and ABCG2 confers resistance to talazoparib, a poly (ADP-Ribose) polymerase inhibitor

AIMS

The overexpression of ABC transporters on cancer cell membranes is one of the most common causes of multidrug resistance (MDR). This study investigates the impact of ABCC1 and ABCG2 on the resistance to talazoparib (BMN-673), a potent poly (ADP-ribose) polymerase (PARP) inhibitor, in ovarian cancer treatment.

METHODS

The cell viability test was used to indicate the effect of talazoparib in different cell lines. Computational molecular docking analysis was conducted to simulate the interaction between talazoparib and ABCC1 or ABCG2. The mechanism of talazoparib resistance was investigated by constructing talazoparib-resistant subline A2780/T4 from A2780 through drug selection with gradually increasing talazoparib concentration.

RESULTS

Talazoparib cytotoxicity decreased in drug-selected or gene-transfected cell lines overexpressing ABCC1 or ABCG2 but can be restored by ABCC1 or ABCG2 inhibitors. Talazoparib competitively inhibited substrate drug efflux activity of ABCC1 or ABCG2. Upregulated ABCC1 and ABCG2 protein expression on the plasma membrane of A2780/T4 cells enhances resistance to other substrate drugs, which could be overcome by the knockout of either gene. In vivo experiments confirmed the retention of drug-resistant characteristics in tumor xenograft mouse models.

CONCLUSIONS

The therapeutic efficacy of talazoparib in cancer may be compromised by its susceptibility to MDR, which is attributed to its interactions with the ABCC1 or ABCG2 transporters. The overexpression of these transporters can potentially diminish the therapeutic impact of talazoparib in cancer treatment.

Foretinib, a c-MET receptor tyrosine kinase inhibitor, tackles multidrug resistance in cancer cells by inhibiting ABCB1 and ABCG2 transporters

BACKGROUND

ABC transporter-mediated multidrug resistance (MDR) remains a major obstacle for cancer pharmacological treatment. Some tyrosine kinase inhibitors (TKIs) have been shown to reverse MDR. The present study was designed to evaluate for the first time whether foretinib, a multitargeted TKI, can circumvent ABCB1 and ABCG2-mediated MDR in treatment-resistant cancer models.

METHODS

Accumulation of fluorescent substrates of ABCB1 and ABCG2 in ABCB1-overexpressing MES-SA/DX5 and ABCG2-overexpressing MCF-7/MX and their parenteral cells was evaluated by flow cytometry. The growth inhibitory activity of single and combination therapy of foretinib and chemotherapeutic drugs on MDR cells was examined by MTT assay. Analysis of combined interaction effects was performed using CalcuSyn software.

RESULTS

It was firstly proved that foretinib increased the intracellular accumulation of rhodamine 123 and mitoxantrone in MES-SA/DX5 and MCF-7/MX cancer cells, with accumulation ratios of 12 and 2.2 at 25 μM concentration, respectively. However, it did not affect the accumulation of fluorescent substrates in the parental cells. Moreover, foretinib synergistically improved the cytotoxic effects of doxorubicin and mitoxantrone. The means of combination index (CI) values at fraction affected (Fa) values of 0.5, 0.75, and 0.9 were 0.64 ± 0.08 and 0.47 ± 0.09, in MES-SA/DX5 and MCF-7/MX cancer cells, respectively. In silico analysis also suggested that the drug-binding domain of ABCB1 and ABCG2 transporters could be considered as potential target for foretinib.

CONCLUSION

Overall, our results suggest that foretinib can target MDR-linked ABCB1 and ABCG2 transporters in clinical cancer therapy.

ATP-Binding Cassette Subfamily G Member 2 in Acute Myeloid Leukemia: A New Molecular Target?

Despite the progress in the knowledge of disease pathogenesis and the identification of many molecular markers as potential targets of new therapies, the cure of acute myeloid leukemia remains challenging. Disease recurrence after an initial response and the development of resistance to old and new therapies account for the poor survival rate and still make allogeneic stem cell transplantation the only curative option. Multidrug resistance (MDR) is a multifactorial phenomenon resulting from host-related characteristics and leukemia factors. Among these, the overexpression of membrane drug transporter proteins belonging to the ABC (ATP-Binding Cassette)-protein superfamily, which diverts drugs from their cellular targets, plays an important role. Moreover, a better understanding of leukemia biology has highlighted that, at least in cancer, ABC protein's role goes beyond simple drug transport and affects many other cell functions. In this paper, we summarized the current knowledge of ABCG2 (formerly Breast Cancer Resistance Protein, BCRP) in acute myeloid leukemia and discuss the potential ways to overcome its efflux function and to revert its ability to confer stemness to leukemia cells, favoring the persistence of leukemia progenitors in the bone marrow niche and justifying relapse also after therapy intensification with allogeneic stem cell transplantation.

Small Molecule Inhibitors Targeting the "Undruggable" Survivin: The Past, Present, and Future from a Medicinal Chemist's Perspective

Survivin, a homodimeric protein and a member of the IAP family, plays a vital function in cell survival and cycle progression by interacting with various proteins and complexes. Its expression is upregulated in cancers but not detectable in normal tissues. Thus, it has been regarded and validated as an ideal cancer target. However, survivin is "undruggable" due to its lack of enzymatic activities or active sites for small molecules to bind/inhibit. Academic and industrial laboratories have explored different strategies to overcome this hurdle over the past two decades, with some compounds advanced into clinical testing. These strategies include inhibiting survivin expression, its interaction with binding partners and homodimerization. Here, we provide comprehensive analyses of these strategies and perspective on different small molecule survivin inhibitors to help drug discovery targeting "undruggable" proteins in general and survivin specifically with a true survivin inhibitor that will prevail in the foreseeable future.

Dacomitinib in EGFR-mutant non-small-cell lung cancer with brain metastasis: a single-arm, phase II study

INTRODUCTION

Dacomitinib showed superior progression-free survival (PFS) and overall survival compared to gefitinib in patients with advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations in the ARCHER1050 study. However, because that study did not include patients with brain metastases, the efficacy of dacomitinib in patients with brain metastases has not been clarified.

PATIENTS AND METHODS

This single-arm phase II study enrolled 30 patients with treatment-naïve advanced NSCLC harboring activating EGFR mutations from January 2021 to June 2021 and started them on dacomitinib (45 mg/day). All patients had non-irradiated brain metastases with a diameter of ≥5 mm. The primary endpoint was confirmed intracranial objective response rate (iORR).

RESULTS

Patients had exon 19 deletions (46.7%) and L858R mutations in exon 21 (55.3%). The confirmed iORR was 96.7% (29/30), with an intracranial complete response of 63.3%. Median intracranial PFS (iPFS) was not reached, with 12- and 18-month iPFS rates of 78.6% [95% confidence interval (CI) 64.8% to 95.4%] and 70.4% (95% CI 54.9% to 90.1%), respectively. In the competing risk analysis, the 12-month cumulative incidence of intracranial progression was 16.7%. Regarding the overall efficacy for intracranial and extracranial lesions, the overall ORR was 96.7%, and the median PFS was 17.5 months (95% CI 15.2 months-not reached). Grade 3 or higher treatment-related adverse events were reported in 16.7% of patients, and 83.3% required a reduced dacomitinib dose to manage adverse events. However, none permanently discontinued dacomitinib treatment due to treatment-related adverse events.

CONCLUSIONS

Dacomitinib has outstanding intracranial efficacy in patients with EGFR-mutant NSCLC with brain metastases.

Evaluation of the FDA-approved kinase inhibitors to uncover the potential repurposing candidates targeting ABC transporters in multidrug-resistant cancer cells: an in silico approach

Multiple drug resistance (MDR) is characterized by the resistance of cancer cells to a broad spectrum of anticancer drugs. The main mechanism underlying the MDR phenotype is the overexpression of ATP-binding cassette (ABC) transporters by promoting active drug efflux from cancer cells. Some small-molecule protein kinase inhibitors have been found to overcome MDR by inhibiting ABC transporters as substrates or modulators. This study investigated the chemical activity of 58 FDA-approved anticancer kinase inhibitors against three multidrug resistance-related proteins. The studied proteins are ATP-Binding Cassette Sub-Family B Member 1 (ABCB1), ATP-Binding Cassette Subfamily C Member 1 (ABCC1), and ATP-binding cassette superfamily G member 2 (ABCG2). The drug-binding domain and ATP binding sites of the proteins were considered the kinase inhibitors' probable target. High-throughput virtual screening and molecular docking were employed to find the hit drugs, and the drugs with the highest binding affinity were further evaluated using the molecular dynamics (MD) simulation. The virtual screening revealed that several kinase inhibitors could be considered potential inhibitors of ABCB1, ABCC1, and ABCG2, among which larotrectinib, entrectinib, and infigratinib showed the highest binding affinity, respectively. Based on the obtained results from MD simulation, these drugs can form strong interactions with the essential residues of the target proteins. In silico investigation revealed that larotrectinib, entrectinib, and infigratinib can target the key residues of the studied proteins. Therefore, these approved kinase inhibitors could be considered potential therapies for MDR cancers by targeting these transporters.Communicated by Ramaswamy H. Sarma.

Advances in the structure, mechanism and targeting of chemoresistance-linked ABC transporters

Cancer cells frequently display intrinsic or acquired resistance to chemically diverse anticancer drugs, limiting therapeutic success. Among the main mechanisms of this multidrug resistance is the overexpression of ATP-binding cassette (ABC) transporters that mediate drug efflux, and, specifically, ABCB1, ABCG2 and ABCC1 are known to cause cancer chemoresistance. High-resolution structures, biophysical and in silico studies have led to tremendous progress in understanding the mechanism of drug transport by these ABC transporters, and several promising therapies, including irradiation-based immune and thermal therapies, and nanomedicine have been used to overcome ABC transporter-mediated cancer chemoresistance. In this Review, we highlight the progress achieved in the past 5 years on the three transporters, ABCB1, ABCG2 and ABCC1, that are known to be of clinical importance. We address the molecular basis of their broad substrate specificity gleaned from structural information and discuss novel approaches to block the function of ABC transporters. Furthermore, genetic modification of ABC transporters by CRISPR-Cas9 and approaches to re-engineer amino acid sequences to change the direction of transport from efflux to import are briefly discussed. We suggest that current information regarding the structure, mechanism and regulation of ABC transporters should be used in clinical trials to improve the efficiency of chemotherapeutics for patients with cancer.

Perspectives on drug repurposing to overcome cancer multidrug resistance mediated by ABCB1 and ABCG2

The overexpression of the human ATP-binding cassette (ABC) transporters in cancer cells is a common mechanism involved in developing multidrug resistance (MDR). Unfortunately, there are currently no approved drugs specifically designed to treat multidrug-resistant cancers, making MDR a significant obstacle to successful chemotherapy. Despite over two decades of research, developing transporter-specific inhibitors for clinical use has proven to be a challenging endeavor. As an alternative approach, drug repurposing has gained traction as a more practical method to discover clinically effective modulators of drug transporters. This involves exploring new indications for already-approved drugs, bypassing the lengthy process of developing novel synthetic inhibitors. In this context, we will discuss the mechanisms of ABC drug transporters ABCB1 and ABCG2, their roles in cancer MDR, and the inhibitors that have been evaluated for their potential to reverse MDR mediated by these drug transporters. Our focus will be on providing an up-to-date report on approved drugs tested for their inhibitory activities against these drug efflux pumps. Lastly, we will explore the challenges and prospects of repurposing already approved medications for clinical use to overcome chemoresistance in patients with high tumor expression of ABCB1 and/or ABCG2.

The AKT inhibitor, MK-2206, attenuates ABCG2-mediated drug resistance in lung and colon cancer cells

Introduction: The overexpression of ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, are two of the major mediators of multidrug resistance (MDR) in cancers. Although multiple ABCB1 and ABCG2 inhibitors have been developed and some have undergone evaluation in clinical trials, none have been clinically approved. The compound, MK-2206, an inhibitor of the protein kinases AKT1/2/3, is undergoing evaluation in multiple clinical trials for the treatment of certain types of cancers, including those resistant to erlotinib. In this in vitro study, we conducted in vitro experiments to determine if MK-2206 attenuates multidrug resistance in cancer cells overexpressing the ABCB1 or ABCG2 transporter. Methodology: The efficacy of MK-2206 (0.03-1 μM), in combination with the ABCB1 transporter sub-strates doxorubicin and paclitaxel, and ABCG2 transporter substrates mitoxantrone, SN-38 and topotecan, were determined in the cancer cell lines, KB-C2 and SW620/Ad300, which overexpress the ABCB1 transporter or H460/MX20 and S1-M1-80, which overexpress the ABCG2 transporter, respectively. The expression level and the localization of ABCG2 transporter on the cancer cells membranes were determined using western blot and immunofluorescence assays, respectively, following the incubation of cells with MK-2206. Finally, the interaction between MK-2206 and human ABCG2 transporter was predicted using computer-aided molecular modeling. Results: MK-2206 significantly increased the efficacy of anticancer compounds that were substrates for the ABCG2 but not the ABCB1 transporter. MK-2206 alone (0.03-1 μM) did not significantly alter the viability of H460/MX20 and S1-M1-80 cancer cells, which overexpress the ABCG2 transporter, compared to cells incubated with vehicle. However, MK-2206 (0.3 and 1 μM) significantly increased the anticancer efficacy of mitoxantrone, SN-38 and topotecan, in H460/MX20 and S1-M1-80 cancer cells, as indicated by a significant decrease in their IC50 values, compared to cells incubated with vehicle. MK-2206 significantly increased the basal activity of the ABCG2 ATPase (EC50 = 0.46 μM) but did not significantly alter its expression level and sub-localization in the membrane. The molecular modeling results suggested that MK-2206 binds to the active pocket of the ABCG2 transporter, by a hydrogen bond, hydrophobic interactions and π-π stacking. Conclusion: These in vitro data indicated that MK-2206 surmounts resistance to mitoxantrone, SN-38 and topotecan in cancer cells overexpressing the ABCG2 transporter. If these results can be translated to humans, it is possible that MK-2206 could be used to surmount MDR in cancer cells overexpressing the ABCG2 transporter.

MiR-125b-5p/STAT3 Axis Regulates Drug Resistance in Osteosarcoma Cells by Acting on ABC Transporters

Background

The poor prognosis of the highly malignant tumor osteosarcoma stems from its drug resistance and therefore exploring its resistance mechanisms will help us identify more effective treatment options. However, the effects of miR-125b-5p on drug resistance in osteosarcoma cells are still unclear.

Methods

To study the effects of miR-125b-5p on drug resistance in osteosarcoma cells. Osteosarcoma-resistant miR-125b-5p was obtained from the databases GeneCards and g:Profiler. CCK8, western blot, and transwell were applied for the detection of the miR-125b-5p effects on proliferation, migration, invasion, apoptosis, and drug resistance in osteosarcoma. Bioinformatics is aimed at demonstrating the targeting factor miR-125b-5p, performing protein interaction enrichment analysis by Metascape, and finally validating by binding sites.

Results

Upregulation of miR-125b-5p restrains proliferation, migration, and invasion of osteosarcoma and promotes apoptosis. In addition, miR-125b-5p can restore drug sensitivity in drug-resistant osteosarcoma. miR-125-5p restrains the signal transducer and inhibits the transcription 3 (STAT3) expression activator via targeting its 3'-UTR. STAT3 affects drug-resistant osteosarcoma to regulate the ABC transporter.

Conclusion

miR-125b-5p/STAT3 axis mediates the drug resistance of osteosarcoma by acting on ABC transporter.

Design, synthesis, and biological evaluation of phenylurea indole derivatives as ABCG2 inhibitors

Three series of phenylurea indole derivatives were synthesized with potent inhibitory activities on ABCG2 with simple and efficient synthetic routes. Among these compounds, four phenylurea indole derivatives 3c-3f with extended π system were discovered as the most potent ABCG2 inhibitors, while these compounds showed no inhibition on ABCB1. Compounds 3c and 3f were selected for further investigation to explore the mechanisms of action on reversing ABCG2-mediated multidrug resistance (MDR). The results revealed that compounds 3c and 3f increased the accumulation of mitoxantrone (MX) in ABCG2-overexpressing cells, but they did not alter the expression level or localization of ABCG2 in cells. In addition, both 3c and 3f significantly stimulated the ATP hydrolysis of ABCG2 transporter indicating that they can be competitive substrates of ABCG2 transporter, and thereby increase the accumulation of mitoxantrone in ABCG2-overexpressing H460/MX20 cells. Both 3c and 3f was docked into the drug-binding site of the human ABCG2 transporter protein (PDB 6FFC) with high affinities. This study showed that extending the π system of phenylurea indole derivatives enhanced their inhibitory activities on ABCG2, which may provide a clue for the further research to discover more potent ABCG2 inhibitors.

Design, Synthesis and Biological Evaluation of Quinazolinamine Derivatives as Breast Cancer Resistance Protein and P-Glycoprotein Inhibitors with Improved Metabolic Stability

A series of twenty-two quinazolinamine derivatives showing potent inhibitory activities on breast cancer resistance protein (BCRP) and p-glycoprotein (P-gp) were synthesized. A cyclopropyl-containing quinazolinamine 22 was identified as a dual BCRP and P-gp inhibitor, while azide-containing quinazolinamine 33 showed BCRP inhibitory activity. These lead compounds were further investigated in a battery of mechanistic experiments. Compound 22 changed the localization of BCRP and P-gp in cells, thus inhibiting the efflux of anticancer drugs by the two ATP-binding cassette (ABC) transporters. In addition, both 22 and 33 significantly stimulated the ATP hydrolysis of the BCRP transporter, indicating that they can be competitive substrates of the BCRP transporter, and thereby increase the accumulation of mitoxantrone in BCRP-overexpressing H460/MX20 cells. Azide derivative 33, exhibited a greater inhibitory effect on BCRP after UV activation and can serve as a valuable probe for investigating the interactions of quinazolinamine derivatives with BCRP. Notably, the dual BCRP and P-gp inhibitors 4-5, 22-24, 27, and BCRP inhibitor 33 showed improved metabolic stability compared to Ko143.

In silico screening of c-Met tyrosine kinase inhibitors targeting nucleotide and drug-substrate binding sites of ABCB1 as potential MDR reversal agents

PURPOSE

Cancer is a significant public health problem and ranks as a leading cause of death globally. Multidrug resistance (MDR) affects the therapeutic potential of conventional chemotherapeutic agents in cancer chemotherapy. Receptor tyrosine kinases (RTKs) are enzymes whose aberrant activation contributes to the tumorigenesis of various types of cancers. The ability of several RTKs, such as c-Met, to reverse ABC transporters mediated MDR was shown before. We aimed to explore the ability of c-Met inhibitors to circumvent MDR in cancer by inhibiting the ABCB1 transporter using in silico studies.

METHODS

Docking virtual screening of several potent and structurally diverse c-Met inhibitors were applied to find repurposed candidates to target the ATP binding sites and drug-substrate binding pockets of the ABCB1 transporter. The selected candidate was subjected to molecular dynamics simulations.

RESULTS

Based on docking findings, among 19 clinical c-Met inhibitors, several drugs, particularly golvatinib, exerted the affinity to both ATP binding sites in the nucleotide-binding domains (NBDs) as well as the drug-substrate binding site in the transmembrane domains (TMDs). Moreover, several non-clinical c-Met inhibitors obtained from the ChEMBL database had strong interactions with TMDs and NBDs, among which CHEMBL1950194 and CHEMBL2385194 compounds showed the highest binding affinity, respectively. Additionally, as a potential repositioning drug, MD simulation studies of golvatinib, corroborated the docking results.

CONCLUSION

We applied docking and molecular dynamics simulations to screen the potential c-Met inhibitors as the MDR reversing agents targeting ATP and drug-substrate binding sites, and the results suggested several repurposed candidate drugs.

Adagrasib, a KRAS G12C inhibitor, reverses the multidrug resistance mediated by ABCB1 in vitro and in vivo

Background

Multidrug resistance (MDR) is a complex phenomenon that frequently leads to chemotherapy failure during cancer treatment. The overexpression of ATP-binding cassette (ABC) transporters represents the major mechanism contributing to MDR. To date, no effective MDR modulator has been applied in clinic. Adagrasib (MRTX849), a specific inhibitor targeting KRAS G12C mutant, is currently under investigation in clinical trials for the treatment of non-small cell lung cancer (NSCLC). This study focused on investigating the circumvention of MDR by MRTX849.

Methods

The cytotoxicity and MDR reversal effect of MRTX849 were assessed by MTT assay. Drug accumulation and drug efflux were evaluated by flow cytometry. The MDR reversal by MRTX849 in vivo was investigated in two ABCB1-overexpressing tumor xenograft models in nude mice. The interaction between MRTX849 and ABCB1 substrate binding sites was studied by the [125I]-IAAP-photoaffinity labeling assay. The vanadate-sensitive ATPase assay was performed to identify whether MRTX849 would change ABCB1 ATPase activity. The effect of MRTX849 on expression of ABCB1 and PI3K/AKT signaling molecules was examined by flow cytometry, Western blot and Quantitative Real-time PCR analyses.

Results

MRTX849 was shown to enhance the anticancer efficacy of ABCB1 substrate drugs in the transporter-overexpressing cells both in vitro and in vivo. The MDR reversal effect was specific against ABCB1 because no similar effect was observed in the parental sensitive cells or in ABCG2-mediated MDR cells. Mechanistically, MRTX849 increased the cellular accumulation of ABCB1 substrates including doxorubicin (Dox) and rhodamine 123 (Rho123) in ABCB1-overexpressing MDR cells by suppressing ABCB1 efflux activity. Additionally, MRTX849 stimulated ABCB1 ATPase activity and competed with [125I]-IAAP for photolabeling of ABCB1 in a concentration-dependent manner. However, MRTX849 did not alter ABCB1 expression or phosphorylation of AKT/ERK at the effective MDR reversal drug concentrations.

Conclusions

In summary, MRTX849 was found to overcome ABCB1-mediated MDR both in vitro and in vivo by specifically attenuating ABCB1 efflux activity in drug-resistant cancer cells. Further studies are warranted to translate the combination of MRTX849 and conventional chemotherapy to clinical application for circumvention of MDR.

Drug-induced liver injury associated with dacomitinib: A case report

Dacomitinib, the second-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has been used as a first-line treatment in non-small cell lung cancer (NSCLC) patients harboring EGFR mutation. In this case, we report a patient with drug-induced liver injury (DILI) associated with the use of dacomitinib. A 59-year-old man with stage IV NSCLC was prescribed with dacomitinib; 37 days after dacomitinib administration, he was admitted to our hospital because of jaundice. Laboratory examinations revealed elevated serum levels of liver enzymes and bilirubin. Following the immediate discontinuation of dacomitinib, liver enzymes decreased but bilirubin continued to rise. Total bilirubin reached the peak (18-fold) on day 26 after dacomitinib termination and normalized on day 146 after dacomitinib discontinuation. A "probable" cause of DILI by dacomitinib was determined based on the Roussel Uclaf Causality Assessment Method. The severity of DILI was assessed as acute liver failure. To our knowledge, this is the first case of DILI caused by dacomitinib monotherapy in a real-world setting. Clinicians should pay particular attention to the possibility of DILI during dacomitinib treatment.

Overcoming multidrug resistance through targeting ABC transporters: lessons for drug discovery

INTRODUCTION

The argument around cancer therapy is an old one. Using chemotherapeutic drugs, as one of the most effective strategies in treatment of malignancies, is restricted by various issues that progress during therapy and avoid achieving clinical endpoints. Multidrug resistance (MDR), frequently mediated by ATP-binding cassette (ABC) transporters, is one of the most recognized obstacles in the success of pharmacological anticancer approaches. These transporters efflux diverse drugs to extracellular environment, causing MDR and responsiveness of tumor cells to chemotherapy diminishes.

AREAS COVERED

Several strategies have been used to overcome MDR phenomenon. Succession in this field requires complete knowledge about features and mechanism of ABC transporters. In this review, conventional synthetic and natural inhibitors are discussed first and then novel approaches including RNA, monoclonal antibodies, nanobiotechnology, and structural modification techniques are represented.

EXPERT OPINION

With increasing frequency of MDR in cancer cells, it is essential to develop new drugs to inhibit MDR. Using knowledge acquired about ABC transporter's structure, rational design of inhibitors is possible. Also, some herbal products have shown to be potential lead compounds in drug discovery for reversal of MDR.

Intrinsically Fluorescent Anti-Cancer Drugs

At present, about one-third of the total protein targets in the pharmaceutical research sector are kinase-based. While kinases have been attractive targets to combat many diseases, including cancer, selective kinase inhibition has been challenging, because of the high degree of structural homology in the active site where many kinase inhibitors bind. Despite efficacy as cancer drugs, kinase inhibitors can exhibit limited target specificity and rationalizing their target profiles in the context of precise molecular mechanisms or rearrangements is a major challenge for the field. Spectroscopic approaches such as infrared, Raman, NMR and fluorescence have the potential to provide significant insights into drug-target and drug-non-target interactions because of sensitivity to molecular environment. This review places a spotlight on the significance of fluorescence for extracting information related to structural properties, discovery of hidden conformers in solution and in target-bound state, binding properties (e.g., location of binding sites, hydrogen-bonding, hydrophobicity), kinetics as well as dynamics of kinase inhibitors. It is concluded that the information gleaned from an understanding of the intrinsic fluorescence from these classes of drugs may aid in the development of future drugs with improved side-effects and less disease resistance.

Plasma exchange treats severe intrahepatic cholestasis caused by dacomitinib: A case report

RATIONALE

Dacomitinib-induced liver injury is often manifested by mild elevations of transaminases and bilirubin, and severe intrahepatic cholestasis caused by dacomitinib for simultaneous taking orally cytochrome P450 2D6 (CYP2D6) competitive substrates has been rarely reported.

PATIENT CONCERNS

The patient was a 69-year-old woman with non-small cell lung cancer (NSCLC) who was prescribed oral dacomitinib for a month; she was given oral loratadine due to "allergic rhinitis" and metoprolol extended action tablets due to "tachycardia" separately for a few days during the course of dacomitinib treatment. The patient developed liver damage, increased fatigue, yellow urine, and pruritus, with significantly elevated serum levels of bilirubin and glutamyltranspetidase.

DIAGNOSIS

Intrahepatic cholestasis, drug-induced liver injury, and NSCLC.

INTERVENTIONS

After admission, the patient was prescribed adenosylmethionine, acetylcysteine, ursodeoxycholic acid capsule, methylprednisolone and fenofibrate for a month, with progressive elevation of liver biochemical parameters. Through drug enzyme gene assays in the liver tissue after percutaneous liver biopsy, we found both CYP2D6*10/*10 and ATP-binding cassette subfamily B member 1 GG variants (rs1045642) positive. After the poor response to the conventional medication, the patient underwent plasma exchange.

OUTCOMES

The patient was discharged after her liver parameters improved; the parameters remained normal at several follow-up visits, and she renewed the NSCLC regimens without dacomitinib after being evaluated by oncologists.

LESSONS

Dacomitinib can induce severe intrahepatic cholestasis. It is considered that patients with intermediate metabolic CYP2D6 are susceptible to drug-induced liver injury caused by dacomitinib; plasma exchange may be an effective treatment.

Cancer multidrug-resistance reversal by ABCB1 inhibition: A recent update

Chemotherapy is one of the most common treatments for cancer that uses one or more anti-cancer drugs as a part of the standardized chemotherapy regimen. Cytotoxic chemicals delay and prevent cancer cells from multiplying, invading, and metastasizing. However, the significant drawbacks of cancer chemotherapy are the lack of selectivity of the cytotoxic drugs to tumour cells and normal cells and the development of resistance by cells for the particular drug or the combination of drugs. Multidrug resistance (MDR) is the low sensitivity of specific cells against drugs associated with cancer chemotherapy. The most common mechanisms of anticancer drug resistance are: (a) drug-dependent MDR (b) target-dependent MDR, and (c) drug target-independent MDR. In all the factors, the overexpression of multidrug efflux systems contributes significantly to the increased resistance in the cancer cells. Multidrug resistance due to efflux of anticancer drugs by membrane ABC transporters includes ABCB1, ABCC1, and ABCG2. ABCB1 inhibition can restore the sensitivity of the cancerous cells toward chemotherapeutic drugs. In this review, we discussed ABCB1 inhibitors under clinical studies with their mode of action, potency and selectivity. Also, we have highlighted the contribution of repurposing drugs, biologics and nano formulation strategies to combat multidrug resistance by modulating the ABCB1 activity.

Multidrug Resistance of Cancer Cells and the Vital Role of P-Glycoprotein

P-glycoprotein (P-gp) is a major factor in the multidrug resistance phenotype in cancer cells. P-gp is a protein that regulates the ATP-dependent efflux of a wide range of anticancer medicines and confers resistance. Due to its wide specificity, several attempts have been made to block the action of P-gp to restore the efficacy of anticancer drugs. The major goal has been to create molecules that either compete with anticancer medicines for transport or function as a direct P-gp inhibitor. Despite significant in vitro success, there are presently no drugs available in the clinic that can "block" P-gp-mediated resistance. Toxicity, unfavourable pharmacological interactions, and a variety of pharmacokinetic difficulties might all be the reason for the failure. On the other hand, P-gp has a significant effect in the body. It protects the vital organs from the entry of foreign bodies and other toxic chemicals. Hence, the inhibitors of P-gp should not hinder its action in the normal cells. To develop an effective inhibitor of P-gp, thorough background knowledge is needed in this field. The main aim of this review article was to set forth the merits and demerits of the action of P-gp on cancer cells as well as on normal cells. The influence of P-gp on cancer drug delivery and the contribution of P-gp to activating drug resistance were also mentioned.

Study on the chemotherapeutic effect and mechanism of cucurbitacin E on laryngeal cancer stem cells

Objectives

Study on the chemotherapeutic effect and mechanism of cucurbitacin E (CuE) on laryngeal cancer stem cells.

Methods

We used flow cytometry to sort out CD133+ laryngeal cancer stem cells; trypan blue rejection assay to detect the survival rate of laryngeal cancer stem cells; Cell counting kit-8 (CCK-8) assay to detect the effect of CuE on the proliferation ability of stem cells and the chemotherapeutic potentiation of doxorubicin; Transwell assay to observe the effect of CuE on the migration ability of stem cells; and Western Blot to detect the effect of CuE on the expression level of stem cell-associated proteins. The tumor volume of nude mice was measured at the end of the experiment, and paraffin sections of nude mice tumor tissues were prepared and stained with Hematoxylin and eosin (H&E). The expression of c-MYC in tumor tissues of nude mice was further detected by immunohistochemistry, and the effect of CuE on the expression level of related proteins in tumor tissues of nude mice was detected by Western Blot.

Results

CuE reduced the survival rate, proliferation ability, and migration ability of laryngeal cancer stem cells in vitro, and that CuE had a chemotherapeutic potentiating effect on doxorubicin. The possible mechanism of the chemotherapeutic effect of CuE was to reduce the expression of c-MYC protein, and the possible mechanism of chemotherapy synergy was to reduce the expression of ABCG2 and P-gp protein.

Conclusion

CuE has a chemotherapeutic effect on laryngeal cancer stem cells, as well as a chemotherapy synergy.

Olaparib Combined With Dacomitinib in Osimertinib-Resistant Brain and Leptomeningeal Metastases From Non-Small Cell Lung Cancer: A Case Report and Systematic Review

Lung cancer patients with brain and leptomeningeal metastases usually have poor prognosis. For those patients with EGFR mutations, osimertinib, a third-generation tyrosine kinase inhibitor (TKI), is the first choice of treatment. However, drug resistance to osimertinib frequently occurs; and to date, the available follow-up treatment strategies have limited efficacy. In this case study, we report that treatments with olaparib, a Poly (ADP-ribose) polymerase (PARP) inhibitor, combined with dacomitinib, a second-generation EGFR TKI, benefited a lung cancer patient with osimertinib-resistant brain and leptomeningeal metastases. This 55-year-old male patient was found to have a pL858R mutation on EGFR exon 21 combined with TP53 and ERBB2 mutations after developing drug resistance to osimertinib treatment. Based on the genetic testing results, he was treated with olaparib and dacomitinib, and obtained 6 months of progression-free survival (PFS) and 13 months of overall survival (OS) after the diagnosis of leptomeningeal metastasis. This case report represents the first study applying PARP inhibitor in combination with dacomitinib in the treatment of leptomeningeal metastases after osimertinib resistance.

Local Anesthetic Ropivacaine Exhibits Therapeutic Effects in Cancers

Despite the significant progress in cancer treatment, new anticancer therapeutics drugs with new structures and/or mechanisms are still in urgent need to tackle many key challenges. Drug repurposing is a feasible strategy in discovering new drugs among the approved drugs by defining new indications. Recently, ropivacaine, a local anesthetic that has been applied in clinical practice for several decades, has been found to possess inhibitory activity and sensitizing effects when combined with conventional chemotherapeutics toward cancer cells. While its full applications and the exact targets remain to be revealed, it has been indicated that its anticancer potency was mediated by multiple mechanisms, such as modulating sodium channel, inducing mitochondria-associated apoptosis, cell cycle arrest, inhibiting autophagy, and/or regulating other key players in cancer cells, which can be termed as multi-targets/functions that require more in-depth studies. In this review, we attempted to summarize the research past decade of using ropivacaine in suppressing cancer growth and sensitizing anticancer drugs both in-vitro and in-vivo, and tried to interpret the underlying action modes. The information gained in these findings may inspire multidisciplinary efforts to develop/discover more novel anticancer agents via drug repurposing.

Novel microtubule inhibitor SQ overcomes multidrug resistance in MCF-7/ADR cells by inhibiting BCRP function and mediating apoptosis

The occurrence of multidrug resistance (MDR) is one of the impediments in the clinical treatment of breast cancer, and MDR breast cancer has abnormally high breast cancer resistance protein (BCRP/ABCG2) expression. However, there are currently no clinical drugs that inhibit this target. Our previous study found that 2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ0814061/SQ), a small molecule drug with low toxicity to normal tissues, could target microtubules, inhibit the proliferation of breast cancer, and reduce its migration and invasion abilities. However, the effect and the underlying mechanism of SQ on MDR breast cancers are still unknown. Therefore, in this study, we investigated the effect of SQ on adriamycin-resistant MCF-7 (MCF-7/ADR) cells and explored the underlying mechanism. The MTT assay showed that SQ had potent cytotoxicity to MCF-7/ADR cells. In particular, the results of western blot and flow cytometry proved that SQ could effectively inhibit the expression of BCRP in MCF-7/ADR cells to decrease its drug delivery activity. In addition, SQ could block the cell cycle at G2/M phase in parental and MCF-7/ADR cells, thereby mediating cell apoptosis, which was related with the inhibition of PI3K-Akt-MDM2 pathway. Taken together, our findings indicate that SQ overcomes multidrug resistance in MCF-7/ADR cells by inhibiting BCRP function and mediating apoptosis through PI3K-Akt-MDM2 pathway inhibition.

ATP-binding cassette (ABC) transporters in cancer: A review of recent updates

The ATP-binding cassette (ABC) transporter superfamily is one of the largest membrane protein families existing in wide spectrum of organisms from prokaryotes to human. ABC transporters are also known as efflux pumps because they mediate the cross-membrane transportation of various endo- and xenobiotic molecules energized by ATP hydrolysis. Therefore, ABC transporters have been considered closely to multidrug resistance (MDR) in cancer, where the efflux of structurally distinct chemotherapeutic drugs causes reduced itherapeutic efficacy. Besides, ABC transporters also play other critical biological roles in cancer such as signal transduction. During the past decades, extensive efforts have been made in understanding the structure-function relationship, transportation profile of ABC transporters, as well as the possibility to overcome MDR via targeting these transporters. In this review, we discuss the most recent knowledge regarding ABC transporters and cancer drug resistance in order to provide insights for the development of more effective therapies.

Circulating Cell-Free DNA as Biomarker of Taxane Resistance in Metastatic Castration-Resistant Prostate Cancer

There are no biomarkers predictive of resistance to docetaxel or cabazitaxel validated for patients with metastatic castration-resistant prostate cancer (mCRPC). We assessed the association between ABCB1 amplification and primary resistance to docetaxel or cabazitaxel for patients with mCRPC, using circulating cell-free DNA (cfDNA). Patients with ≥1 plasma sample drawn within 12 months before starting docetaxel (cohort A) or cabazitaxel (cohort B) for mCRPC were identified from the Dana-Farber Cancer Institute IRB approved database. Sparse whole genome sequencing was performed on the selected cfDNA samples and tumor fractions were estimated using the computational tool ichorCNA. We evaluated the association between ABCB1 amplification or other copy number alterations and primary resistance to docetaxel or cabazitaxel. Of the selected 176 patients, 45 samples in cohort A and 21 samples in cohort B had sufficient tumor content. No significant association was found between ABCB1 amplification and primary resistance to docetaxel (p = 0.58; odds ratio (OR) = 1.49) or cabazitaxel (p = 0.97; OR = 1.06). No significant association was found between exploratory biomarkers and primary resistance to docetaxel or cabazitaxel. In this study, ABCB1 amplification did not predict primary resistance to docetaxel or cabazitaxel for mCRPC. Future studies including ABCB1 amplification in a suite of putative biomarkers and a larger cohort may aid in drawing definitive conclusions.

Lapatinib and poziotinib overcome ABCB1-mediated paclitaxel resistance in ovarian cancer

Conventional frontline treatment for ovarian cancer consists of successive chemotherapy cycles of paclitaxel and platinum. Despite the initial favorable responses for most patients, chemotherapy resistance frequently leads to recurrent or refractory disease. New treatment strategies that circumvent or prevent mechanisms of resistance are needed to improve ovarian cancer therapy. We established in vitro paclitaxel-resistant ovarian cancer cell line and organoid models. Gene expression differences in resistant and sensitive lines were analyzed by RNA sequencing. We manipulated candidate genes associated with paclitaxel resistance using siRNA or small molecule inhibitors, and then screened the cells for paclitaxel sensitivity using cell viability assays. We used the Bliss independence model to evaluate the anti-proliferative synergy for drug combinations. ABCB1 expression was upregulated in paclitaxel-resistant TOV-21G (q < 1x10-300), OVCAR3 (q = 7.4x10-156) and novel ovarian tumor organoid (p = 2.4x10-4) models. Previous reports have shown some tyrosine kinase inhibitors can inhibit ABCB1 function. We tested a panel of tyrosine kinase inhibitors for the ability to sensitize resistant ABCB1-overexpressing ovarian cancer cell lines to paclitaxel. We observed synergy when we combined poziotinib or lapatinib with paclitaxel in resistant TOV-21G and OVCAR3 cells. Silencing ABCB1 expression in paclitaxel-resistant TOV-21G and OVCAR3 cells reduced paclitaxel IC50 by 20.7 and 6.2-fold, respectively. Furthermore, we demonstrated direct inhibition of paclitaxel-induced ABCB1 transporter activity by both lapatinib and poziotinib. In conclusion, lapatinib and poziotinib combined with paclitaxel synergizes to inhibit the proliferation of ABCB1-overexpressing ovarian cancer cells in vitro. The addition of FDA-approved lapatinib to second-line paclitaxel therapy is a promising strategy for patients with recurrent ovarian cancer.

Successful treatment of 2 patients with brain metastases from non-small cell lung cancer with epidermal growth factor receptor mutation receiving dacomitinib: A case report

RATIONALE

Approximately 20% of patients with non-small cell lung cancer (NSCLC) are diagnosed with brain metastasis, which is related to poor survival outcomes. The ability of tyrosine kinase inhibitor drugs to penetrate the blood-brain barrier makes them a potential option for intracranial metastases. Dacomitinib, an irreversible second-generation pan-HER tyrosine kinase inhibitor, has become a standard therapy for patients with epidermal growth factor receptor mutations. However, its efficacy in patients with brain metastases (BMs) is not yet established. Here, we present 2 patients with epidermal growth factor receptor-mutant NSCLC with brain metastasis. After initiation of dacomitinib as first-line treatment, a significant clinical response was achieved, and a long-lasting complete remission was achieved in 1 patient up to this date.

PATIENT CONCERN

Case 1 was a 47-year-old man who was admittedtothe hospital because of recurrent cough and expectoration for >1 year. Chest computed tomography scans revealed a high-density shadow in the left upper lobe. Cranial magnetic resonance imaging indicated an abnormal nodular enhancement in the right cerebellar hemisphere. Case 2 was a 55-year-old man with a chief complaint of intermittent cough and expectoration for >1 month. Chest computed tomography revealed a high-density mass in the left superior lobe. Magnetic resonance imaging of the central nervous system revealed 2 abnormal nodular enhancements in the left frontal lobe.

DIAGNOSIS

Both patients were diagnosed with lung adenocarcinoma by bronchoscopy and lymph node biopsy.

INTERVENTIONS

Both patients received dacomitinib 30 mg once daily as first-line therapy for 8 and 11 months, respectively until disease progression.

OUTCOME

After treatment with dacomitinib, both patients achieved complete response in BMs. Progression-free survival was 11 and 8 months, respectively.

LESSONS

Dacomitinib strongly controlled BMs in patients with advanced NSCLC, and the adverse reactions were tolerable. Dacomitinib may be considered a new treatment option for these patients. Further prospective studies are recommended to confirm this conclusion.

NCX-4040, a Unique Nitric Oxide Donor, Induces Reversal of Drug-Resistance in Both ABCB1- and ABCG2-Expressing Multidrug Human Cancer Cells

The emergence of multidrug resistance (MDR) in the clinic is a significant problem for a successful treatment of human cancers. Overexpression of various ABC transporters (P-gp, BCRP and MRP's), which remove anticancer drugs in an ATP-dependent manner, is linked to the emergence of MDR. Attempts to modulate MDR have not been very successful in the clinic. Furthermore, no single agent has been found to significantly inhibit their functions to overcome clinical drug resistance. We have previously shown that nitric oxide (^●NO) inhibits ATPase functions of ABC transporters, causing reversal of resistance to clinically active anticancer drugs. In this study, we have used cytotoxicity and molecular docking studies to show that NCX4040, a nitric oxide donor related to aspirin, inhibited the functions of ATPase which resulted in significant reversal of resistance to both adriamycin and topotecan in P-gp- and BCRP-expressing human cancer cell lines, respectively. We also used several other cytotoxic nitric oxide donors, e.g., molsidomine and S-nitroso glutathione; however, both P-gp- and BCRP-expressing cells were found to be highly resistant to these NO-donors. Molecular docking studies showed that NCX4040 binds to the nucleotide binding domains of the ATPase and interferes with further binding of ATP, resulting in decreased activities of these transporters. Our results are extremely promising and suggest that nitric oxide and other reactive species delivered to drug resistant tumor cells by well-designed nitric oxide donors could be useful in sensitizing anticancer drugs in multidrug resistant tumors expressing various ABC transporters.

Nucleolin-Targeting AS1411 Aptamer-Modified Micelle for the Co-Delivery of Doxorubicin and miR-519c to Improve the Therapeutic Efficacy in Hepatocellular Carcinoma Treatment

BACKGROUND

Multidrug resistance (MDR) has emerged to be a major hindrance in cancer therapy, which contributes to the reduced sensitivity of cancer cells toward chemotherapeutic drugs mainly owing to the over-expression of drug efflux transporters. The combination of gene therapy and chemotherapy has been considered as a potential approach to improve the anti-cancer efficacy by reversing the MDR effect.

MATERIALS AND METHODS

The AS1411 aptamer-functionalized micelles were constructed through an emulsion/solvent evaporation strategy for the simultaneous co-delivery of doxorubicin and miR-519c. The therapeutic efficacy and related mechanism of micelles were explored based on the in vitro and in vivo active targeting ability and the suppression of MDR, using hepatocellular carcinoma cell line HepG2 as a model.

RESULTS

The micelle was demonstrated to possess favorable cellular uptake and tumor penetration ability by specifically recognizing the nucleolin in an AS1411 aptamer-dependent manner. Further, the intracellular accumulation of doxorubicin was significantly improved due to the suppression of ABCG2-mediated drug efflux by miR-519c, resulting in the efficient inhibition of tumor growth.

CONCLUSION

The micelle-mediated co-delivery of doxorubicin and miR-519c provided a promising strategy to obtain ideal anti-cancer efficacy through the active targeting function and the reversion of MDR.

Cationic polymer synergizing with chemotherapeutics and re-purposing antibiotics against cancer cells

Chemotherapy is one of the most effective treatments for cancer. However, toxicity and the development of drug resistance have become the major hurdles to the commonly used chemotherapeutics such as doxorubicin and paclitaxel. Antibiotics have also been used as anti-cancer drugs due to their anti-proliferative and cytotoxic effects. However, these anti-tumor antibiotics like ciprofloxacin face the similar resistance and toxicity issues. In this study, we used a quaternary ammonium-functionalized cationic polycarbonate to synergize with the existing chemotherapeutics and re-purpose antibiotics to address the resistance and toxicity issues. When used in combination with the drugs, the cationic polymer induced 2-3 fold more damage in the cancer cell membrane within 2 hours, thus enhancing the uptake of chemotherapeutics up to 2.5 fold more into the breast, liver and even chemotherapeutics-resistant cancer cells. On the other hand, the chemotherapeutics increased the cellular uptake of polymer. The combined effects resulted in 3-10 fold reduction in IC₅₀ of chemotherapy drugs and yielded therapeutic synergy at a clinically-relevant concentration range of drugs when treating multiple types of cancer cells, while the use of guanidinium-functionalized polymer capable of membrane translocation did not lead to a synergistic effect. Thus, the quaternary ammonium-functionalized cationic polymer can increase the therapeutic efficacies of existing drugs, mitigating toxicities by lowering required dosage and circumventing drug resistance via its membrane disruption mechanism. The findings of this study provide insights into designing future anticancer therapy.

The third-generation EGFR inhibitor almonertinib (HS-10296) resensitizes ABCB1-overexpressing multidrug-resistant cancer cells to chemotherapeutic drugs

The overexpression of the human ATP-binding cassette (ABC) drug transporter ABCB1 (P-glycoprotein, P-gp) or ABCG2 (breast cancer resistance protein, BCRP) in cancer cells often contributes significantly to the development of multidrug resistance (MDR) in cancer patients. Previous reports have demonstrated that some epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) could modulate the activity of ABCB1 and/or ABCG2 in human cancer cells, whereas some EGFR TKIs are transport substrates of these transporters. Almonertinib (HS-10296) is a promising, orally available third-generation EGFR TKI for the treatment of EGFR T790M mutation-positive non-small cell lung cancer (NSCLC) in patients who have progressed on or after other EGFR TKI therapies. Additional clinical trials are currently in progress to study almonertinib as monotherapy and in combination with other agents in patients with NSCLC. In the present work, we found that neither ABCB1 nor ABCG2 confers significant resistance to almonertinib. More importantly, we discovered that almonertinib was able to reverse MDR mediated by ABCB1, but not ABCG2, in multidrug-resistant cancer cells at submicromolar concentrations by inhibiting the drug transport activity of ABCB1 without affecting its expression level. These findings are further supported by in silico docking of almonertinib in the drug-binding pocket of ABCB1. In summary, our study revealed an additional activity of almonertinib to re-sensitize ABCB1-overexpressing multidrug-resistant cancer cells to conventional chemotherapeutic drugs, which may be beneficial for cancer patients and warrant further investigation.

Rational Design of Hyaluronic Acid-Based Copolymer-Mixed Micelle in Combination PD-L1 Immune Checkpoint Blockade for Enhanced Chemo-Immunotherapy of Melanoma

The application of combinational therapy breaks the limitation of monotherapy and achieves better clinical benefit for tumor therapy. Herein, a hyaluronic acid/Pluronic F68-based copolymer-mixed micelle was constructed for targeted delivery of chemotherapeutical agent docetaxel (PHDM) in combination with programmed cell death ligand-1(PD-L1) antibody. When PHDM+anti-PDL1 was injected into the blood system, PHDM could accumulate into tumor sites and target tumor cells via CD44-mediated endocytosis and possess tumor chemotherapy. While anti-PDL1 could target PD-L1 protein expressed on surface of tumor cells to the immune checkpoint blockade characteristic for tumor immunotherapy. This strategy could not only directly kill tumor cells but also improve CD8+ T cell level and facilitate effector cytokines release. In conclusion, the rational-designed PHDM+anti-PDL1 therapy strategy creates a new way for tumor immune-chemotherapy.

The Novel Benzamide Derivative, VKNG-2, Restores the Efficacy of Chemotherapeutic Drugs in Colon Cancer Cell Lines by Inhibiting the ABCG2 Transporter

The overexpression of ATP-binding cassette transporter, ABCG2, plays an important role in mediating multidrug resistance (MDR) in certain types of cancer cells. ABCG2-mediated MDR can significantly attenuate or abrogate the efficacy of anticancer drugs by increasing their efflux from cancer cells. In this study, we determined the efficacy of the novel benzamide derivative, VKNG-2, to overcome MDR due to the overexpression of the ABCG2 transporter in the colon cancer cell line, S1-M1-80. In vitro, 5 μM of VKNG-2 reversed the resistance of S1-M1-80 cell line to mitoxantrone (70-fold increase in efficacy) or SN-38 (112-fold increase in efficacy). In contrast, in vitro, 5 μM of VKNG-2 did not significantly alter either the expression of ABCG2, AKT, and PI3K p110β protein or the subcellular localization of the ABCG2 protein compared to colon cancer cells incubated with the vehicle. Molecular docking data indicated that VKNG-2 had a high docking score (-10.2 kcal/mol) for the ABCG2 transporter substrate-drug binding site whereas it had a low affinity on ABCB1 and ABCC1 transporters. Finally, VKNG-2 produced a significant concentration-dependent increase in ATPase activity (EC50 = 2.3 µM). In conclusion, our study suggests that in vitro, VKNG-2 reverses the resistance of S1-M1-80, a cancer cell line resistant to mitoxantrone and SN-38, by inhibiting the efflux function of the ABCG2 transporter.

Anlotinib suppresses metastasis and multidrug resistance via dual blockade of MET/ABCB1 in colorectal carcinoma cells

Anlotinib, a highly selective multi-targeted tyrosine kinase inhibitor (TKI) has therapeutic effects on non-small-cell lung cancer (NSCLC). In this study, the anti-tumor activity and molecular mechanism of anlotinib in metastatic colorectal cancer (mCRC) was explored. The anti-angiogenesis, anti-metastasis, anti-proliferative, and anti-multidrug resistance efficacy of anlotinib were analyzed by using in vitro and in vivo models of human CRC cells. The results indicated that anlotinib boosted chemo-sensitivity of CRC cells, and restrained its proliferation. Besides the suppression of the MET signaling pathway, anlotinib also inhibited invasion and migration of CRC cells. Furthermore, anlotinib prevented VEGF-induced angiogenesis, N-cadherin (CDH2)-induced cell migration, and reversed ATP-binding cassette subfamily B member 1 (ABCB1) -mediated CRC multidrug resistance in CRC. The CRC liver metastasis and subcutaneously implanted xenograft model testified that anlotinib could inhibit proliferation and liver metastasis in CRC cells. Such an observation suggested that a combination of anlotinib with anti-cancer drugs could attenuate angiogenesis, metastasis, proliferative, and multidrug resistance, which constitutes a novel treatment strategy for CRC patients with metastasis.

HDAC6 inhibition enhances the anti-tumor effect of eribulin through tubulin acetylation in triple-negative breast cancer cells

PURPOSE

Improved prognosis for triple-negative breast cancer (TNBC) has plateaued and the development of novel therapeutic strategies is required. This study aimed to explore the anti-tumor effect of combined eribulin and HDAC inhibitor (vorinostat: VOR, pan-HDAC inhibitor and ricolinostat: RICO, selective HDAC6 inhibitor) treatment for TNBC.

METHODS

The effect of eribulin in combination with an HDAC inhibitor was tested in three TNBC cell lines (MDA-MB-231, Hs578T, and MDA-MB-157) and their eribulin-resistant derivatives. The expression of acetylated α-tubulin was analyzed by Western blotting for TNBC cells and immunohistochemical analyses for clinical specimens obtained from breast cancer patients who were treated with eribulin.

RESULTS

The simultaneous administration of low concentrations (0.2 μM) of VOR or RICO enhanced the anti-tumor effect of eribulin in MDA-MB-231 and Hs578T cells but not in MDA-MB-157 cells. Meanwhile, pretreatment with 5 μM of VOR or RICO enhanced eribulin sensitivity in all three cell lines. Low concentration of VOR or RICO increased acetylated α-tubulin expression in MDA-MB-231 and Hs578T cells. In contrast, whereas 5 μM of VOR or RICO increased the expression of acetylated α-tubulin in MDA-MB-157 cells, low concentrations did not. Eribulin increased the expression of acetylated α-tubulin in MDA-MB-231 and Hs578T cells but not in MDA-MB-157 cells. These phenomena were also observed in eribulin-resistant cells. Immunohistochemical analyses revealed that the expression of acetylated α-tubulin was increased after eribulin treatment in TNBC.

CONCLUSIONS

HDAC6 inhibition enhances the anti-tumor effect of eribulin through the acetylation of α-tubulin. This combination therapy could represent a novel therapeutic strategy for TNBC.

Rational drug design of 6-substituted 4-anilino-2-phenylpyrimidines for exploration of novel ABCG2 binding site

In the search for novel, highly potent, and nontoxic adjuvant chemotherapeutics to resolve the major issue of ABC transporter-mediated multidrug resistance (MDR), pyrimidines were discovered as a promising compound class of modern ABCG2 inhibitors. As ABCG2-mediated MDR is a major obstacle in leukemia, pancreatic carcinoma, and breast cancer chemotherapy, adjuvant chemotherapeutics are highly desired for future clinical oncology. Very recently, docking studies of one of the most potent reversers of ABCG2-mediated MDR were reported and revealed a putative second binding pocket of ABCG2. Based on this (sub)pocket, a series of 16 differently 6-substituted 4-anilino-2-phenylpyrimidines was designed and synthesized to explore the potential increase in inhibitory activity of these ABCG2 inhibitors. The compounds were assessed for their influence on the ABCG2-mediated pheophorbide A transport, as well as the ABCB1- and ABCC1-mediated transport of calcein AM. They were additionally evaluated in MDR reversal assays to determine their half-maximal reversal concentration (EC₅₀). The 6-substitution did not only show increased toxicity against ABCG2-overexpressing cells in combination with SN-38 but also a negative influence on cell viability in general. Nevertheless, several candidates had EC₅₀ values in the low double-digit nanomolar concentration range, qualifying them as some of the most potent reversers of ABCG2-mediated MDR. In addition, five novel multitarget ABCB1, ABCC1, and ABCG2 inhibitors were discovered, four of them exerting their inhibitory power against the three stated transporters at least in the single-digit micromolar concentration range.

Poziotinib Inhibits the Efflux Activity of the ABCB1 and ABCG2 Transporters and the Expression of the ABCG2 Transporter Protein in Multidrug Resistant Colon Cancer Cells

Simple Summary

Globally, colorectal cancer (CRC) is a leading cause of cancer deaths and chemotherapy, in combination with radiotherapy when appropriate, is used to treat the majority of CRC patients. However, the acquisition or development of drug resistance can decrease, or even abolish, the efficacy of chemotherapy. ATP-binding cassette (ABC) transporters, particularly, the ABCB1 and ABCG2 transporter, are mediators of multidrug resistance (MDR) in certain types of cancer cells. The aim of our in vitro study was to determine if poziotinib can overcome MDR to certain chemotherapeutic drugs in colon cancer cells. Our results indicated that in MDR CRC cell lines, poziotinib inhibits the transport function of the ABCB1 and ABCG2 transporters, increasing the intracellular accumulation of certain anticancer drugs, and thus, their efficacy. Furthermore, poziotinib decreased the expression of the ABCG2 protein. Therefore, if our results can be translated to humans, they suggest that using poziotinib in combination with certain anticancer drugs may be of therapeutic benefit in colorectal cancer patients.

Abstract

Colorectal cancer (CRC) is a leading cause of cancer deaths in the United States. Currently, chemotherapy is a first-line treatment for CRC. However, one major drawback of chemotherapy is the emergence of multidrug resistance (MDR). It has been well-established that the overexpression of the ABCB1 and/or ABCG2 transporters can produce MDR in cancer cells. In this study, we report that in vitro, poziotinib can antagonize both ABCB1- and ABCG2-mediated MDR at 0.1–0.6 μM in the human colon cancer cell lines, SW620/Ad300 and S1-M1-80. Mechanistic studies indicated that poziotinib increases the intracellular accumulation of the ABCB1 transporter substrates, paclitaxel and doxorubicin, and the ABCG2 transporter substrates, mitoxantrone and SN-38, by inhibiting their substrate efflux function. Accumulation assay results suggested that poziotinib binds reversibly to the ABCG2 and ABCB1 transporter. Furthermore, western blot experiments indicated that poziotinib, at 0.6 μM, significantly downregulates the expression of the ABCG2 but not the ABCB1 transporter protein, suggesting that the ABCG2 reversal effect produced by poziotinib is due to transporter downregulation and inhibition of substrate efflux. Poziotinib concentration-dependently stimulated the ATPase activity of both ABCB1 and ABCG2, with EC₅₀ values of 0.02 μM and 0.21 μM, respectively, suggesting that it interacts with the drug-substrate binding site. Molecular docking analysis indicated that poziotinib binds to the ABCB1 (−6.6 kcal/mol) and ABCG2 (−10.1 kcal/mol) drug-substrate binding site. In summary, our novel results show that poziotinib interacts with the ABCB1 and ABCG2 transporter, suggesting that poziotinib may increase the efficacy of certain chemotherapeutic drugs used in treating MDR CRC.

Remarkable response to dacomitinib in a patient with leptomeningeal carcinomatosis due to EGFR-mutant non-small cell lung cancer

Dacomitinib, a second‐generation epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitor, is a standard therapeutic option for patients with EGFR‐mutant non‐small cell lung cancer (NSCLC). However, its efficacy in patients with central nervous system lesions is unclear. Here, we describe a case of EGFR‐mutant NSCLC whose neurological symptoms were due to leptomeningeal carcinomatosis that was successfully treated with dacomitinib. After initiation of dacomitinib, the neurological symptoms of the patient were remarkably improved and leptomeningeal dissemination and brain metastases were shown to have regressed on magnetic resonance imaging (MRI) scan. To our knowledge, this is the first report showing the efficacy of dacomitinib in a patient with leptomeningeal carcinomatosis due to EGFR‐mutant NSCLC. The current case suggests that dacomitinib is a novel treatment option for patients with EGFR‐mutant NSCLC accompanied by central nervous system lesions, even those with symptomatic leptomeningeal carcinomatosis.

Key points

Significant findings of the study

This is the first report showing the efficacy of dacomitinib in a patient with leptomeningeal carcinomatosis due to EGFR‐mutant NSCLC.

What this study adds

The current case suggests that dacomitinib is a novel treatment option for patients with EGFR‐mutant NSCLC accompanied by CNS lesions, even in those with symptomatic leptomeningeal carcinomatosis.