Implications of ABCG2 Expression on Irinotecan Treatment of Colorectal Cancer Patients: A Review

Oncostatin M reverses ABCG2-mediated mitoxantrone resistance

Mitoxantrone resistant variant of SW620 line was developed, characterized and subsequently used as a model system to determine oncostatin M ability to modulate MDR phenomenon. The selection regimen allowed for overexpression of ABCG2 and ABCB1 both at the RNA and protein level, which was further confirmed by functional assays. Oncostatin M supplementation resulted in partial reversal of MDR phenotype by decreasing overexpression of ABCG2 demonstrating for the first time the ability of this cytokine for selective down-regulation of one of MDR proteins.

Dorsomorphin attenuates ABCG2-mediated multidrug resistance in colorectal cancer

Colorectal cancer is a common malignant tumor with high mortality, for which chemotherapy resistance is one of the main reasons. The high expression of ABCG2 in the cancer cells and expulsion of anticancer drugs directly cause multidrug resistance (MDR). Therefore, the development of new ABCG2 inhibitors that block the active causes of MDR may provide a strategy for the treatment of colorectal cancer. In this study, we find that dorsomorphin (also known as compound C or BML-275) potently inhibits the transporter activity of ABCG2, thereby preserving the chemotherapeutic agents mitoxantrone and doxorubicin to antagonize MDR in ABCG2-overexpressing colorectal cancer cells. Additionally, dorsomorphin does not alter ABCG2 protein expression. The results of molecular docking studies show that dorsomorphin is bound stably to the ABCG2-binding pocket, suggesting that dorsomorphin is a potent ABCG2 inhibitor that attenuates ABCG2-mediated MDR in colorectal cancer.

Fluorescence-Guided Spatial Drug Screening in 3D Colorectal Cancer Spheroids

The limited recapitulation of critical cancer features in 2D cultures causes poor translatability of preclinical results from in vitro assays to in vivo tumor models. This contributes to slow drug development with a low success rate. 3D cultures better recapitulate the tumor microenvironment, enabling more accurate predictions when screening drug candidates and improving the development of chemotherapeutics. Platinum (Pt) (IV) compounds are promising prodrugs designed to reduce the severe systemic toxicity of widely used Food and Drug Administration (FDA)-approved Pt(II) drugs such as cisplatin. Here, this work presents spatiotemporal evaluations in 3D colorectal cancer (CRC) spheroids of mitochondria-targeting Pt(IV) complexes. CRC spheroids provide a greater pathophysiological recapitulation of in vivo tumors than 2D cultures by a marked upregulation of the ABCG2 chemoresistance marker expression. Furthermore, new 3D-staining protocols are introduced to evaluate the real-time decrease in mitochondria membrane potential (ΔΨ) in CRC spheroids, and a Pt-sensing dye to quantify the Pt mitochondrial accumulation. Finally, this work demonstrates a correlation between in vitro results and the efficacy of the compounds in vivo. Overall, the CRC spheroids represent a fast and cost-effective model to assess the behavior of Pt compounds in vitro and predict their translational potential in CRC treatment.

MiR-548c-3p through suppressing Tyms and Abcg2 increases the sensitivity of colorectal cancer cells to 5-fluorouracil

Background

Colorectal cancer, is one of most prevalent the cancer in the world. 5-Fluorouracil is a standard chemotherapeutic drug while the acquisition of resistance to 5-Fluorouracil is one of the problems during treatment. In this study, we aimed to find the miRNAs that modulate the expression of Tyms and Abcg2 as resistance-inducing genes in the resistant cell lines to 5-Fluorouracil.

Methods

5-Fluorouracil-resistant HCT116 and SW480 cell lines were generated by consecutive treatment of cells with 5-Fluorouracil. This resistance induction was validated by MTT assays. The expression of the Tyms and Abcg2 gene and miR-548c-3p were studied by quantitative real-time PCR in the cell lines.

Results

We hypothesized that miR-548c-3p is targeting Tyms and Abcg2 simultaneously. Increased expression Tyms gene in the two most resistant cell lines derived from HCT116 and all resistant cell lines derived from SW480 except one were seen. Increased expression of Abcg2 was observed in the most resistant HCT116-derived cell line and all resistant cell lines, derived from SW480. In all resistant cell lines, the expression of miR-548c-3p was decreased.

Conclusion

It can be concluded downregulation of miR548c-3p is in line with Tyms and Abcg2 overexpression in resistant cell lines to 5-Fluorouracil.

Shielding and nurturing: Fibronectin as a modulator of cancer drug resistance

Resistance to chemotherapy and targeted therapies constitute a common hallmark of most cancers and represent a dominant factor fostering tumor relapse and metastasis. Fibronectin, an abundant extracellular matrix glycoprotein, has long been proposed to play an important role in the pathobiology of cancer. Recent research has unraveled the role of Fibronectin in the onset of chemoresistance against a variety of antineoplastic drugs including DNA-damaging agents, hormone receptor antagonists, tyrosine kinase inhibitors, microtubule destabilizing agents, etc. The current review summarizes the role played by Fibronectin in mediating drug resistance against diverse anticancer drugs. We have also discussed how the aberrant expression of Fibronectin drives the oncogenic signaling pathways ultimately leading to drug resistance through the inhibition of apoptosis, promotion of cancer cell growth and proliferation.

ABCG2 Gene and ABCG2 Protein Expression in Colorectal Cancer-In Silico and Wet Analysis

ABCG2 (ATP-binding cassette superfamily G member 2) is a cell membrane pump encoded by the ABCG2 gene. ABCG2 can protect cells against compounds initiating and/or intensifying neoplasia and is considered a marker of stem cells responsible for cancer growth, drug resistance and recurrence. Expression of the ABCG2 gene or its protein has been shown to be a negative prognostic factor in various malignancies. However, its prognostic significance in colorectal cancer remains unclear. Using publicly available data, ABCG2 was shown to be underexpressed in colon and rectum adenocarcinomas, with lower expression compared to both the adjacent nonmalignant lung tissues and non-tumour lung tissues of healthy individuals. This downregulation could result from the methylation level of some sites of the ABCG2 gene. This was connected with microsatellite instability, weight and age among patients with colon adenocarcinoma, and with tumour localization, population type and age of patients for rectum adenocarcinoma. No association was found between ABCG2 expression level and survival of colorectal cancer patients. In wet analysis of colorectal cancer samples, neither ABCG2 gene expression, analysed by RT-PCR, nor ABCG2 protein level, assessed by immunohistochemistry, was associated with any clinicopathological factors or overall survival. An ABCG2-centered protein-protein interaction network build by STRING showed proteins were found to be involved in leukotriene, organic anion and xenobiotic transport, endodermal cell fate specification, and histone methylation and ubiquitination. Hence, ABCG2 underexpression could be an indicator of the activity of certain signalling pathways or protein interactors essential for colorectal carcinogenesis.

Resistance to TOP-1 Inhibitors: Good Old Drugs Still Can Surprise Us

Irinotecan (SN-38) is a potent and broad-spectrum anticancer drug that targets DNA topoisomerase I (Top1). It exerts its cytotoxic effects by binding to the Top1-DNA complex and preventing the re-ligation of the DNA strand, leading to the formation of lethal DNA breaks. Following the initial response to irinotecan, secondary resistance is acquired relatively rapidly, compromising its efficacy. There are several mechanisms contributing to the resistance, which affect the irinotecan metabolism or the target protein. In addition, we have demonstrated a major resistance mechanism associated with the elimination of hundreds of thousands of Top1 binding sites on DNA that can arise from the repair of prior Top1-dependent DNA cleavages. Here, we outline the major mechanisms of irinotecan resistance and highlight recent advancements in the field. We discuss the impact of resistance mechanisms on clinical outcomes and the potential strategies to overcome resistance to irinotecan. The elucidation of the underlying mechanisms of irinotecan resistance can provide valuable insights for the development of effective therapeutic strategies.

Facile construction of irinotecan loaded mesoporous nano-formulation with surface-initiated polymerization to improve stimuli-responsive drug delivery for breast cancer therapy

This work uses rice husk to fabricate mesoporous silica nanoparticles (D-RMN) for breast cancer therapy. The biocompatible dual-responsive (DAN-RMN) was developed by polymerizing acrylic acid (AA) and n-isopropyl acrylamide (NIPAM) on the DV-RMN surface monomeric ratio to increase drug delivery efficiency after vinyl groups were added to the surface of nanoparticles (DAN-RMN). Various analytical and spectroscopical methods characterized the fabricated nanoparticles. Additionally, further encapsulation with SN-38 into the DAN-RMN enhances anticancer efficiency. The in-vitro controlled SN-38 release displayed remarkable temperature and pH response. The MTT assay established the biocompatibility and cytotoxicity of natural sources of silica and DAN-RMN. The fabricated SN-38@DAN-RMN nanoparticles effectively killed the MDA-MB-231 and 4T1 cancerous cells, confirmed by the MTT assay. The IC₅₀ values of SN-38@DAN-RMN in MDA-MB-231 and 4T1 for 1.8 μg/mL and 1.7 μg/mL, respectively. In addition, acridine orange-ethidium bromide (AO-EB) dual staining methods were used to determine morphological changes of cell shrinkage and fragmentation. Nuclear staining methods confirmed the nuclear fragmentation and condensation of the cells. Further, the cell death was examined using dual staining Annexin V-FITC/PI in flow cytometric analyses to assess apoptosis in the MDA-MB-231 and 4T1 cell lines. The apoptotic cell ratio of SN-38@DAN-RMN in MDA-MB-231 and 4T1 for 27.8 and 32.8, respectively. Since there is no drug leakage in the blood while the carrier is in circulation, the DAN-RMN nanocarrier may be used for targeted and stimuli-responsive administration using ultrasound imaging.

miRNAs are now starring in "No Time to Die: Overcoming the chemoresistance in cancer"

Cancer is a leading cause of death globally, with about 19.3 million new cases reported each year. Current therapies for cancer management include-chemotherapy, radiotherapy, and surgery. However, they are loaded with side effects and tend to cause toxicity in the patient's body posttreatment, ultimately hindering the response towards the treatment building up resistance. This is where noncoding RNAs such as miRNAs help provide us with a helping hand for taming the chemoresistance and providing potential holistic cancer management. MicroRNAs are promising targets for anticancer therapy as they perform critical regulatory roles in various signaling cascades related to cell proliferation, apoptosis, migration, and invasion. Combining miRNAs and anticancer drugs and devising a combination therapy has managed cancer well in various independent studies. This review aims to provide insights into how miRNAs play a mechanistic role in cancer development and progression and regulate drug resistance in various types of cancers. Furthermore, next-generation novel therapies using miRNAs in combination with anticancer treatments in multiple cancers have been put forth and how they improve the efficacy of the treatments. Exemplary studies currently in the preclinical and clinical models have been summarized. Ultimately, we briefly talk through the challenges that come forward with it and minimize them.

Drug-Drug Interactions and Disease Status Are Associated with Irinotecan-induced Hepatotoxicity: A Cross-Sectional Study in Shanghai

Irinotecan-induced hepatotoxicity can cause severe clinical complications in patients; however, the underlying mechanism and factors affecting hepatotoxicity have rarely been investigated. In this cross-sectional study, we screened all clinical, demographic, medication and genetic variables among 126 patients receiving irinotecan and explored potential associations with the incidence and time to onset of irinotecan-induced hepatotoxicity. Approximately 38.9% of the patients suffered from hepatotoxicity after irinotecan administration. The presence of cardiovascular diseases (CVDs) increases the incidence of hepatotoxicity approximately 2.9-fold and doubles the hazard of time to hepatotoxicity. Patients with liver metastasis had a more than 4-fold higher risk of hepatotoxicity and a 3.5-fold increased hazard of time to hepatotoxicity compared to those without liver metastasis. Patients who took CYP3A inducers had a 4.4-fold increased incidence of hepatotoxicity, and furthermore, concomitant use of platinum-based antineoplastics revealed 4.2 times the hazard of time to hepatotoxicity compared to those receiving antimetabolites. The cumulative dose of irinotecan (5-9 cycles) increased hepatotoxicity by 8.5 times. However, the genotypes and phenotypes of UGT1A1*28/*6 failed to be predictive factors of hepatotoxicity. The findings of this study suggest that irinotecan-induced hepatotoxicity is not directly associated with genetic variables but is mostly related to concomitant use of CYP3A inducers and platinum, as well as the presence of liver metastasis and CVD. Thus, close monitoring of liver function is recommended, especially in patients with liver impairment or using CYP3A inducers and platinum antineoplastic drugs, which may be the best way to prevent hepatotoxicity. This article is protected by copyright. All rights reserved.

The Membrane Electrical Potential and Intracellular pH as Factors Influencing Intracellular Ascorbate Concentration and Their Role in Cancer Treatment

Ascorbate is an important element of a variety of cellular processes including the control of reactive oxygen species levels. Since reactive oxygen species are implicated as a key factor in tumorigenesis and antitumor therapy, the injection of a large amount of ascorbate is considered beneficial in cancer therapy. Recent studies have shown that ascorbate can cross the plasma membrane through passive diffusion. In contrast to absorption by active transport, which is facilitated by transport proteins (SVCT1 and SVCT2). The passive diffusion of a weak acid across membranes depends on the electrostatic potential and the pH gradients. This has been used to construct a new theoretical model capable of providing steady-state ascorbate concentration in the intracellular space and evaluating the time needed to reach it. The main conclusion of the analysis is that the steady-state intracellular ascorbate concentration weakly depends on its serum concentration but requires days of exposure to saturate. Based on these findings, it can be hypothesized that extended oral ascorbate delivery is possibly more effective than a short intravenous infusion of high ascorbate quantities.

VKNG-1 Antagonizes ABCG2-Mediated Multidrug Resistance via p-AKT and Bcl-2 Pathway in Colon Cancer: In Vitro and In Vivo Study

The emergence of multidrug resistance (MDR) to chemotherapeutic drugs is a major problem in the therapy of cancer. Knowledge of the mechanisms of drug resistance in cancer is necessary for developing efficacious therapies. ATP-binding cassette (ABC) transporters are transmembrane proteins that efflux chemotherapeutic drugs from cancer cells, thereby producing MDR. Our research efforts have led to the discovery of VKNG-1, a compound that selectively inhibits the ABCG2 transporter and reverses resistanctabe to standard anticancer drugs both in vitro and in vivo. VKNG-1, at 6 µM, selectively inhibited ABCG2 transporter and sensitized ABCG2-overexpressing drug-resistant cancer cells to the ABCG2 substrate anticancer drugs mitoxantrone, SN-38, and doxorubicin in ABCG2-overexpressing colon cancers. VKNG- 1 reverses ABCG2-mediated MDR by blocking ABCG2 efflux activity and downregulating ABCG2 expression at the mRNA and protein levels. Moreover, VKNG-1 inhibits the level of phosphorylated protein kinase B (PKB/p-AKT), and B-cell lymphoma-2 (Bcl-2) protein which may overcome resistance to anticancer drugs. However, the in vitro translocation of ABCG2 protein did not occur in the presence of 6 µM of VKNG-1. In addition, VKNG-1 enhanced the anticancer efficacy of irinotecan in ABCG2- overexpressing mouse tumor xenografts. Overall, our results suggest that VKNG-1 may, in combination with certain anticancer drugs, represent a treatment to overcome ABCG2-mediated MDR colon cancers.

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.

Battling Chemoresistance in Cancer: Root Causes and Strategies to Uproot Them

With nearly 10 million deaths, cancer is the leading cause of mortality worldwide. Along with major key parameters that control cancer treatment management, such as diagnosis, resistance to the classical and new chemotherapeutic reagents continues to be a significant problem. Intrinsic or acquired chemoresistance leads to cancer recurrence in many cases that eventually causes failure in the successful treatment and death of cancer patients. Various determinants, including tumor heterogeneity and tumor microenvironment, could cause chemoresistance through a diverse range of mechanisms. In this review, we summarize the key determinants and the underlying mechanisms by which chemoresistance appears. We then describe which strategies have been implemented and studied to combat such a lethal phenomenon in the management of cancer treatment, with emphasis on the need to improve the early diagnosis of cancer complemented by combination therapy.

Investigating the Mechanism of Scutellariae barbata Herba in the Treatment of Colorectal Cancer by Network Pharmacology and Molecular Docking

Background

Colorectal cancer (CRC) is one of the most common gastrointestinal tumors, which accounts for approximately 10% of all diagnosed cancers and cancer deaths worldwide per year. Scutellariae barbatae Herba (SBH) is one of the most frequently used traditional Chinese medicine (TCM) in the treatment of CRC. Although many experiments have been carried out to explain the mechanisms of SBH, the mechanisms of SBH have not been illuminated fully. Thus, we constructed a network pharmacology and molecular docking to investigate the mechanisms of SBH.

Methods

We adopted active constituent prescreening, target predicting, protein-protein interaction (PPI) analysis, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, differentially expressed gene analysis, and molecular docking to establish a system pharmacology database of SBH against CRC.

Results

A total of 64 active constituents of SBH were obtained and 377 targets were predicted, and the result indicated that quercetin, luteolin, wogonin, and apigenin were the main active constituents of SBH. Glucocorticoid receptor (NR3C1), pPhosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA), cellular tumor antigen p53 (TP53), transcription factor AP-1 (JUN), mitogen-activated protein kinase 1 (MAPK1), Myc protooncogene protein (MYC), cyclin-dependent kinase 1 (CDK1), and broad substrate specificity ATP-binding cassette transporter ABCG2 (ABCG2) were the major targets of SBH in the treatment of CRC. GO analysis illustrated that the core biological process regulated by SBH was the regulation of the cell cycle. Thirty pathways were presented and 8 pathways related to CRC were involved. Molecular docking presented the binding details of 3 key targets with 6 active constituents.

Conclusions

The mechanisms of SBH against CRC depend on the synergistic effect of multiple active constituents, multiple targets, and multiple pathways.

TRIM Proteins in Colorectal Cancer: TRIM8 as a Promising Therapeutic Target in Chemo Resistance

Colorectal cancer (CRC) represents one of the most widespread forms of cancer in the population and, as all malignant tumors, often develops resistance to chemotherapies with consequent tumor growth and spreading leading to the patient’s premature death. For this reason, a great challenge is to identify new therapeutic targets, able to restore the drugs sensitivity of cancer cells. In this review, we discuss the role of TRIpartite Motifs (TRIM) proteins in cancers and in CRC chemoresistance, focusing on the tumor-suppressor role of TRIM8 protein in the reactivation of the CRC cells sensitivity to drugs currently used in the clinical practice. Since the restoration of TRIM8 protein levels in CRC cells recovers chemotherapy response, it may represent a new promising therapeutic target in the treatment of CRC.

Establishment and Characterization of an Irinotecan-Resistant Human Colon Cancer Cell Line

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Irinotecan is widely used as a chemotherapeutic drug to treat CRC. However, the mechanisms of acquired resistance to irinotecan in CRC remain inconclusive. In the present study, we established a novel irinotecan-resistant human colon cell line to investigate the underlying mechanism(s) of irinotecan resistance, particularly the overexpression of ABC transporters. The irinotecan-resistant S1-IR20 cell line was established by exposing irinotecan to human S1 colon cancer cells. MTT cytotoxicity assay was carried out to determine the drug resistance profile of S1-IR20 cells. The drug-resistant cells showed about 47-fold resistance to irinotecan and cross-resistance to ABCG2 substrates in comparison with S1 cells. By Western blot analysis, S1-IR20 cells showed significant increase of ABCG2, but not ABCB1 or ABCC1 in protein expression level as compared to that of parental S1 cells. The immunofluorescence assay showed that the overexpressed ABCG2 transporter is localized on the cell membrane of S1-IR20 cells, suggesting an active efflux function of the ABCG2 transporter. This finding was further confirmed by reversal studies that inhibiting efflux function of ABCG2 was able to completely abolish drug resistance to irinotecan as well as other ABCG2 substrates in S1-IR20 cells. In conclusion, our work established an in vitro model of irinotecan resistance in CRC and suggested ABCG2 overexpression as one of the underlying mechanisms of acquired resistance to irinotecan. This novel resistant cell line may enable future studies to overcome drug resistance in vitro and improve CRC treatment in vivo.

Gutting it Out: Developing Effective Immunotherapies for Patients With Colorectal Cancer

Risk factors for colorectal cancer (CRC) include proinflammatory diets, sedentary habits, and obesity, in addition to genetic syndromes that predispose individuals to this disease. Current treatment relies on surgical excision and cytotoxic chemotherapies. There has been a renewed interest in immunotherapy as a treatment option for CRC given the success in melanoma and microsatellite instable (MSI) CRC. Immunotherapy with checkpoint inhibitors only plays a role in the 4%-6% of patients with MSIhigh tumors and even within this subpopulation, response rates can vary from 30% to 50%. Most patients with CRC do not respond to this modality of treatment, even though colorectal tumors are frequently infiltrated with T cells. Tumor cells limit apoptosis and survive following intensive chemotherapy leading to drug resistance and induction of autophagy. Pharmacological or molecular inhibition of autophagy improves the efficacy of cytotoxic chemotherapy in murine models. The microbiome clearly plays an etiologic role, in some or most colon tumors, realized by elegant findings in murine models and now investigated in human clinical trials. Recent results have suggested that cancer vaccines may be beneficial, perhaps best as preventive strategies. The search for therapies that can be combined with current approaches to increase their efficacy, and new knowledge of the biology of CRC are pivotal to improve the care of patients suffering from this disease. Here, we review the basic immunobiology of CRC, current "state-of-the-art" immunotherapies and define those areas with greatest therapeutic promise for the future.

Implications of ABCC4-Mediated cAMP Eflux for CRC Migration

Colorectal cancer (CRC) presents significant molecular heterogeneity. The cellular plasticity of epithelial to mesenchymal transition (EMT) is one of the key factors responsible for the heterogeneous nature of metastatic CRC. EMT is an important regulator of ATP binding cassette (ABC) protein expression; these proteins are the active transporters of a broad range of endogenous compounds and anticancer drugs. In our previous studies, we performed a transcriptomic and functional analysis of CRC in the early stages of metastasis induced by the overexpression of Snail, the transcription factor involved in EMT initiation. Interestingly, we found a correlation between the Snail expression and ABCC4 (MRP4) protein upregulation. The relationship between epithelial transition and ABCC4 expression and function in CRC has not been previously defined. In the current study, we propose that the ABCC4 expression changes during EMT and may be differentially regulated in various subpopulations of CRC. We confirmed that ABCC4 upregulation is correlated with the phenotype conversion process in CRC. The analysis of Gene Expression Omnibus (GEO) sets showed that the ABCC4 expression was elevated in CRC patients. The results of a functional study demonstrated that, in CRC, ABCC4 can regulate cell migration in a cyclic nucleotide-dependent manner.

Significance of aldo-keto reductase 1C3 and ATP-binding cassette transporter B1 in gain of irinotecan resistance in colon cancer cells

Irinotecan (CPT11) is widely prescribed for treatment of various intractable cancers such as advanced and metastatic colon cancer cells, but its continuous treatment promotes the resistance development. In this study, we established CPT11-resistant variants of three human colon cancer (DLD1, RKO and LoVo) cell lines, and found that gain of the resistance elicited an up-regulation of aldo-keto reductase (AKR) 1C3 in the cells. Additionally, the sensitivity to CPT11 toxicity was decreased and increased by overexpression and knockdown, respectively, of the enzyme. Moreover, the resistant cells suppressed formation of reactive 4-hydroxy-2-nonenal by CPT11 treatment, and the suppressive effect was almost completely abolished by addition of an AKR1C3 inhibitor. These results suggest that up-regulated AKR1C3 contributes to promotion of the chemoresistance by detoxifying the reactive aldehyde. Western blot and real-time polymerase-chain reaction analyses and ATP-binding cassette (ABC) B1-functional assay revealed that, among three ABC transporters, ABCB1 was the most highly up-regulated by development of the CPT11 resistance, inferring a significant contribution of pregnane-X receptor-dependent signaling to the ABCB1 up-regulation. The combined treatment with inhibitors of AKR1C3 and ABCB1 potently sensitized the resistant cells to CPT11 and its active metabolite SN38. Taken together, our results suggest that combination of AKR1C3 and ABCB1 inhibitors is effective as adjuvant therapy to enhance CPT11 sensitivity of intractable colon cancer cells.

BMS-599626, a Highly Selective Pan-HER Kinase Inhibitor, Antagonizes ABCG2-Mediated Drug Resistance

Simple Summary

ABC transporters comprise a large group of ATP binding plasma membrane proteins, classified into subfamilies A-G, that transport substrates out of cells to maintain homeostasis. Prolonged exposure to chemotherapeutic drugs leads to increased expression of ABC transporters in cancer cells, resulting in increased efflux and decreased efficacy of anti-neoplastic agents. We found that BMS-599626, at 300 nM, inhibited the function of ABCG2, thereby increasing the efficacy of substrate chemotherapeutic drugs in wild-type as well as mutant ABCG2 overexpressing cells. In addition, BMS-599626 did not alter the expression or intracellular localization of ABCG2 but produced its reversal effect by decreasing efflux and increasing the intracellular accumulation of substrate chemotherapeutic drugs. Finally, BMS-5999626 also inhibited ABCG2 mediated ATP hydrolysis. Overall, our results show that administration of BMS-599626 along with chemotherapeutic drugs can improve the efficacy of chemotherapy in ABC transporter overexpressing cancer cells.

Abstract

Multidrug resistance (MDR) associated with the overexpression of ABC transporters is one of the key causes of chemotherapy failure. Various compounds blocking the function and/or downregulating the expression of these transporters have been developed over the last few decades. However, their potency and toxicity have always been a concern. In this report, we found that BMS-599626 is a highly potent inhibitor of the ABCG2 transporter, inhibiting its efflux function at 300 nM. Our study repositioned BMS-599626, a highly selective pan-HER kinase inhibitor, as a chemosensitizer in ABCG2-overexpressing cell lines. As shown by the cytotoxicity assay results, BMS-599626, at noncytotoxic concentrations, sensitizes ABCG2-overexpressing cells to topotecan and mitoxantrone, two well-known substrates of ABCG2. The results of our radioactive drug accumulation experiment show that the ABCG2-overexpressing cells, treated with BMS-599626, had an increase in the accumulation of substrate chemotherapeutic drugs, as compared to their parental subline cells. Moreover, BMS-599626 did not change the protein expression or cell surface localization of ABCG2 and inhibited its ATPase activity. Our in-silico docking study also supports the interaction of BMS-599626 with the substrate-binding site of ABCG2. Taken together, these results suggest that administration of chemotherapeutic drugs, along with nanomolar concentrations (300 nM) of BMS-599626, may be effective against ABCG2-mediated MDR in clinical settings.

Combating Drug Resistance in Colorectal Cancer Using Herbal Medicines

Colorectal cancer (CRC) is one of the most prevalent and lethal cancer types around the world. Most of the CRC patients are treated with chemotherapeutic drugs alone or combined. However, up to 90% of metastatic cancer patients experience the failure of treatment mostly because of the acquired drug resistance, which can be led to multidrug resistance (MDR). In this study, we reviewed the recent literature which studied potential CRC MDR reversal agents among herbal medicines (HMs). Among abundant HMs, 6 single herbs, Andrographis paniculata, Salvia miltiorrhiza, Hedyotis diffusa, Sophora flavescens, Curcuma longa, Bufo gargarizans, and 2 formulae, Pien Tze Huang and Zhi Zhen Fang, were found to overcome CRC MDR by two or more different mechanisms, which could be a promising candidate in the development of new drugs for adjuvant CRC chemotherapy.

High Doses of Δ9-Tetrahydrocannabinol Might Impair Irinotecan Chemotherapy: A Review of Potentially Harmful Interactions

This review proposes the hypothesis that the effectiveness of irinotecan chemotherapy might be impaired by high doses of concomitantly administered Δ⁹-tetrahydrocannabinol (THC). The most important features shared by irinotecan and THC, which might represent sources of potentially harmful interactions are: first-pass hepatic metabolism mediated by cytochrome P450 (CYP) enzyme CYP3A4; glucuronidation mediated by uridine diphosphate glycosyltransferase (UGT) enzymes, isoforms 1A1 and 1A9; transport of parent compounds and their metabolites via canalicular ATP-binding cassette (ABC) transporters ABCB1 and ABCG2; enterohepatic recirculation of both parent compounds, which leads to an extended duration of their pharmacological effects; possible competition for binding to albumin; butyrylcholinesterase (BChE) inhibition by THC, which might impair the conversion of parent irinotecan into the SN-38 metabolite; mutual effects on mitochondrial dysfunction and induction of oxidative stress; potentiation of hepatotoxicity; potentiation of genotoxicity and cytogenetic effects leading to genome instability; possible neurotoxicity; and effects on bilirubin. The controversies associated with the use of highly concentrated THC preparations with irinotecan chemotherapy are also discussed. Despite all of the limitations, the body of evidence provided here could be considered relevant for human-risk assessments and calls for concern in cases when irinotecan chemotherapy is accompanied by preparations rich in THC.

ABCG2 Protein Levels and Association to Response to First-Line Irinotecan-Based Therapy for Patients with Metastatic Colorectal Cancer

In this study we investigated the use of cancer cell protein expression of ABCG2 to predict efficacy of systemic first-line irinotecan containing therapy in patients with metastatic colorectal cancer (mCRC). From a Danish national cohort, we identified 119 mCRC patients treated with irinotecan containing therapy in first-line setting. Among these, 108 were eligible for analyses. Immunohistochemistry (IHC) analyses were performed on the primary tumor tissue in order to classify samples as high or low presence of ABCG2 protein. Data were then associated with patient outcome (objective response (OR), progression free survival (PFS) and overall survival (OS)). ABCG2 protein expression in the basolateral membrane was high (score 3+) in 33% of the patients. Exploratory analyses revealed a significant interaction between ABCG2 score, adjuvant treatment and OR (p = 0.041) in the 101 patients with evaluable disease. Patients with low ABCG2 (score 0-2) and no prior adjuvant therapy had a significantly higher odds ratio of 5.6 (Confidence Interval (CI) 1.68-18.7; p = 0.005) for obtaining OR. In contrast, no significant associations between ABCG2 expression and PFS or OS were found. These results suggest that measurement of the ABCG2 drug efflux pump might be used to select patients with mCRC for irinotecan treatment. However, additional studies are warranted before conclusions regarding a clinical use can be made. Moreover, patients with high ABCG2 immunoreactivity could be candidates for specific ABCG2 inhibition treatment in combination with irinotecan.

Irinotecan-Still an Important Player in Cancer Chemotherapy: A Comprehensive Overview

Irinotecan has been used in the treatment of various malignancies for many years. Still, the knowledge regarding this drug is expanding. The pharmacogenetics of the drug is the crucial component of response to irinotecan. Furthermore, new formulations of the drug are introduced in order to better deliver the drug and avoid potentially life-threatening side effects. Here, we give a comprehensive overview on irinotecan’s molecular mode of action, metabolism, pharmacogenetics, and toxicity. Moreover, this article features clinically used combinations of the drug with other anticancer agents and introduces novel formulations of drugs (e.g., liposomal formulations, dendrimers, and nanoparticles). It also outlines crucial mechanisms of tumor cells’ resistance to the active metabolite, ethyl-10-hydroxy-camptothecin (SN-38). We are sure that the article will constitute an important source of information for both new researchers in the field of irinotecan chemotherapy and professionals or clinicians who are interested in the topic.

An Explorative Analysis of ABCG2/TOP-1 mRNA Expression as a Biomarker Test for FOLFIRI Treatment in Stage III Colon Cancer Patients: Results from Retrospective Analyses of the PETACC-3 Trial

Biomarker-guided treatment for patients with colon cancer is needed. We tested ABCG2 and topoisomerase 1 (TOP1) mRNA expression as predictive biomarkers for irinotecan benefit in the PETACC-3 patient cohort. The present study included 580 patients with mRNA expression data from Stage III colon cancer samples from the PETACC-3 study, which randomized the patients to Fluorouracil/leucovorin (5FUL) +/- irinotecan. The primary end-points were recurrence free survival (RFS) and overall survival (OS). Patients were divided into one group with high ABCG2 expression (above median) and low TOP-1 expression (below 75 percentile) ("resistant") (n = 216) and another group including all other combinations of these two genes ("sensitive") (n = 364). The rationale for the cut-offs were based on the distribution of expression levels in the PETACC-3 Stage II set of patients, where ABCG2 was unimodal and TOP1 was bimodal with a high expression level mode in the top quarter of the patients. Cox proportional hazards regression was used to estimate the hazard ratios and the association between variables and end-points and log-rank tests to assess the statistical significance of differences in survival between groups. Kaplan-Meier estimates of the survival functions were used for visualization and estimation of survival rates at specific time points. Significant differences were found for both RFS (Hazard ratio (HR): 0.63 (0.44-0.92); p = 0.016) and OS (HR: 0.60 (0.39-0.93); p = 0.02) between the two biomarker groups when the patients received FOLFIRI (5FUL+irinotecan). Considering only the Microsatellite Stable (MSS) and Microsatellite Instability-Low (MSI-L) patients (n = 470), the differences were even more pronounced. In contrast, no significant differences were observed between the groups when patients received 5FUL alone. This study shows that the combination of ABCG2 and TOP1 gene expression significantly divided the Stage III colon cancer patients into two groups regarding benefit from adjuvant treatment with FOLFIRI but not 5FUL.

miR-200b-3p mitigates oxaliplatin resistance via targeting TUBB3 in colorectal cancer

BACKGROUND

Numerous abnormally expressed miRs have been reported involved in oxaliplatin (L-OHP) resistance of colorectal cancer (CRC). The present study aimed to investigate whether miR-200b-3p could regulate L-OHP resistance via targeting TUBB3 in CRC cells.

METHODS

L-OHP resistant HT29 and HCT116 cells were exposed to escalating concentrations of L-OHP up to 30 μm. The effect of miR-200b-3p on L-OHP resistant CRC cells was then evaluated using the cell counting kit-8 (CCK-8) assay. CRC cell apoptosis was detected using Annexin V-FITC/PI double staining. Bioinformatics algorithms and luciferase reporter assays were also performed to investigate whether TUBB3 was a direct target of miR-200b-3p.

RESULTS

miR-200b-3p declined in L-OHP resistant CRC tissues and cell lines, and the overexpression of miR-200b-3p elevated the L-OHP sensitivity in L-OHP resistant HT29 and HCT116 cells. In addition, we determined the potential mechanisms underlying miR-200b-3p-mediated reversal of L-OHP resistance by mediating its downstream target TUBB3, and the overexpression of miR-200b-3p could induce migration and growth inhibition and apoptosis in L-OHP resistant HT29 and HCT116 cells by silencing βIII-tubulin protein expression. However, the overexpression of TUBB3 reversed miR-200b-3p mimic-induced migration, as well as growth inhibition and apoptosis, in L-OHP resistant CRC cells.

CONCLUSIONS

miR-200b-3p improved L-OHP resistance and induced growth inhibition and cell apoptosis in L-OHP resistant CRC cells, and the underlying mechanism was mediated, at least partially, through the suppression of βIII-tubulin protein expression.

Topoisomerase inhibitors promote cancer cell motility via ROS-mediated activation of JAK2-STAT1-CXCL1 pathway

Background

Topoisomerase inhibitors (TI) can inhibit cell proliferation by preventing DNA replication, stimulating DNA damage and inducing cell cycle arrest. Although these agents have been commonly used in the chemotherapy for the anti-proliferative effect, their impacts on the metastasis of cancer cells remain obscure.

Methods

We used the transwell chamber assay to test effects of Topoisomerase inhibitors Etoposide (VP-16), Adriamycin (ADM) and Irinotecan (CPT-11) on the migration and invasion of cancer cells. Conditioned medium (CM) from TI-treated cells was subjected to Mass spectrometry screening. Gene silencing, neutralizing antibody, and specific chemical inhibitors were used to validate the roles of signaling molecules.

Results

Our studies disclosed that TI could promote the migration and invasion of a subset of cancer cells, which were dependent on chemokine (C-X-C motif) ligand 1 (CXCL1). Further studies disclosed that TI enhanced phosphorylation of Janus kinase 2 (JAK2) and Signal transducers and activators of transcription 1 (STAT1). Silencing or chemical inhibition of JAK2 or STAT1 abrogated TI-induced CXCL1 expression and cell motility. Moreover, TI increased cellular levels of reactive oxygen species (ROS) and promoted oxidation of Protein Tyrosine Phosphatase 1B (PTP1B), while reduced glutathione (GSH) reversed TI-induced JAK2-STAT1 activation, CXCL1 expression, and cell motility.

Conclusions

Our study demonstrates that TI can promote the expression and secretion of CXCL1 by elevating ROS, inactivating PTP1B, and activating JAK2-STAT1 signaling pathway, thereby promoting the motility of cancer cells.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1353-2) contains supplementary material, which is available to authorized users.

Toward a better understanding of the mechanism of action for intra-arterial delivery of irinotecan from DC Bead(TM) (DEBIRI)

DC Bead is designed for the embolization of liver malignancies combined with local sustained chemotherapy delivery. It was first demonstrated around a decade ago that irinotecan could be loaded into DC Bead and used in a transarterially directed procedure to treat colorectal liver metastases, commonly referred to as drug-eluting bead with irinotecan (DEBIRI). Despite numerous reports of its safe and effective use in treating colorectal liver metastases patients, there remains a perceived fundamental paradox as to how this treatment works. This review of the mechanism of action of DEBIRI provides a rationale for why intra-arterial delivery of this prodrug from an embolic bead provides for enhanced tumor selectivity, sparing the normal liver while reducing adverse side effects associated with the irinotecan therapy.

Expression of Aldehyde Dehydrogenase (ALDH1) and ATP Binding Cassette Transporter G2 (ABCG2) in Iraqi Patients with Colon Cancer and the Relation with Clinicopathological Features

Tumor initiation cells or cancer stem cell markers ABCG2 and ALDH1 play pivotal roles in invasion, metastasis and resistance to cytotoxic agents. In this study, we evaluated the expression levels of ALDH1 and ABCG2 in Iraqi patients with colon cancer and/or benign colon tumors. We also investigated the association between the expression levels of these markers and patient clincopathological features. The expression levels of ALDH1 and ABCG2 in cancer tissues as well as in benign tumor samples were determined by immunohistochemistry using tumor tissues microarray of TNM (Tumor, Node, Metastasis) in 42 patients with colon cancer samples as well as in 18 corresponding benign tumors. Immunohistochemistry showed that ALDH1 and ABCG2 expression levels increased to 80% and 76%, respectively in colon cancer tissues as compared to 33% and 28% in benign tumor tissues. The expression levels of ALDH1 and ABCG2 were associated with tumor stages. No significant association was found between the expressions levels of these markers and tumor size, gender, patients' age, and lymph node involvement. These results indicate that the expression levels of ALDH1 and ABCG2 increased in colon cancer tissues compared to benign tumor tissues in Iraqi patients.

UBE2C Induces Cisplatin Resistance via ZEB1/2-Dependent Upregulation of ABCG2 and ERCC1 in NSCLC Cells

Objectives

Cisplatin (DDP) is one of the most commonly used chemotherapeutic drugs for several cancers, including non-small-cell lung cancer (NSCLC). However, resistance to DDP eventually develops, limiting its further application. New therapy targets are urgently needed to reverse DDP resistance.

Methods

The mRNA expression of UBE2C, ZEB1/2, ABCG2, and ERCC1 was analyzed by reverse transcription-polymerase chain reaction. The protein levels of these molecules were analyzed by Western blotting and immunofluorescent staining. Cell proliferation was detected by CCK8 and MTT assays. Cell migration and invasion were analyzed by wound healing assay and Transwell assays. Promoter activities and gene transcription were analyzed by luciferase reporter assay.

Results

In this study, we examined the effect of UBE2C and ZEB1/2 expression levels in DDP-resistant cells of NSCLC. We confirmed that aberrant expression of UBE2C and ZEB1/2 plays a critical role in repressing the DDP sensitivity to NSCLC cells. Additionally, knockdown of UBE2C significantly sensitized resistant cells to DDP by repressing the expression of ZEB1/2. Mechanistic investigations indicated that UBE2C transcriptionally regulated ZEB1/2 by accelerating promoter activity. This study revealed that ZEB1/2 promotes the epithelial mesenchymal transition and expression of ABCG2 and ERCC1 to participate in UBE2C-mediated NSCLC DDP-resistant cell progression, metastasis, and invasion.

Conclusion

UBE2C may be a novel therapy target for NSCLC for sensitizing cells to the chemotherapeutic agent DDP.

Drug resistance and new therapies in colorectal cancer

Colorectal cancer (CRC) is often diagnosed at an advanced stage when tumor cell dissemination has taken place. Chemo- and targeted therapies provide only a limited increase of overall survival for these patients. The major reason for clinical outcome finds its origin in therapy resistance. Escape mechanisms to both chemo- and targeted therapy remain the main culprits. Here, we evaluate major resistant mechanisms and elaborate on potential new therapies. Amongst promising therapies is α-amanitin antibody-drug conjugate targeting hemizygous p53 loss. It becomes clear that a dynamic interaction with the tumor microenvironment exists and that this dictates therapeutic outcome. In addition, CRC displays a limited response to checkpoint inhibitors, as only a minority of patients with microsatellite instable high tumors is susceptible. In this review, we highlight new developments with clinical potentials to augment responses to checkpoint inhibitors.