The Different Mechanisms of Cancer Drug Resistance: A Brief Review

Theranostic combinatorial drug-loaded coated cubosomes for enhanced targeting and efficacy against cancer cells

Cubosomes, a product of nanobioengineering, are self-structured lipid nanoparticles that act like drug-loaded theranostic probes. Here, we describe a simple method for the preparation of combinatorial drug-loaded cubosomes with, proof-of-principle, therapeutic effect against cancer cells, along with diagnostic capabilities. Anticancer drugs cisplatin and paclitaxel were loaded in the cubosomes in combination. The cubosomes were coated with a layer of poly-Ɛ-lysine, which helped avoid the initial burst release of drug and allowed for a slow and sustained release for better efficacy. Cubosomes were imaged by transmission electron microscope, and their dispersion analyzed in vitro by differential scanning calorimetric and X-ray diffractogram studies. The microscopic images depicted spherical polyangular structures, which are easily distinguishable. The analyses revealed that the drug is uniformly dispersed all through the cubosomes. Further characterization was carried out by zeta-potential measurement, in vitro release, and entrapment efficiency studies. The in vitro studies established that the coating of cubosomes successfully reduced the burst release of drugs initially and confirmed a slow, sustained release over increased time. Comparative cytotoxicity of coated, uncoated, and blank cubosomes was evaluated, using human hepatoma HepG2 cell line, and the formulations were found to be entirely nontoxic, similar to the blank ones. The therapeutic efficiency of the cubosomes against HeLa cells was confirmed by the impedance measurement and fluorescent imaging. Furthermore, the reduction in impedance in cells treated with coated combinatorial cubosomes proved the impairment of HeLa cells, as confirmed by fluorescence microscopy.

Synthesis of 2-deoxy-d-glucose coated Fe3O4 nanoparticles for application in targeted delivery of the Pt(iv) prodrug of cisplatin – a novel approach in chemotherapy

Pt(IV) prodrug of cisplatin was loaded on 2DG functionalized silica coated Fe₃O₄ nanoparticles. The formulation alone exhibited biocompatibility whereas Pt(IV) loaded formulation exhibited cytotoxicity comparable with cisplatin.

Tumor Microenvironment - Selective Pressures Boosting Cancer Progression

In 2018, 9.6 million deaths from cancer were estimated, being this disease the second leading cause of death worldwide. Notwithstanding all the efforts developed in prevention, diagnosis and new treatment approaches, chemoresistance seems to be inevitable, leading to cancer progression, recurrence and affecting the outcome of the disease. As more and more evidence support that cancer is an evolutionary and ecological process, this concept is rarely applied in the clinical context. In fact, cancer cells emerge and progress within an ecological niche - the tumor microenvironment - that is shared with several other cell types and that is continuously changing. Therefore, the tumor microenvironment imposes several selective pressures on cancer cells such as acidosis, hypoxia, competition for space and resources, immune predation and anti-cancer therapies, that cancer cells must be able to adapt to or will face extinction.In here, the role of the tumor microenvironment selective pressures on cancer progression will be discussed, as well as the targeting of its features/components as strategies to fight cancer.

ABC-transporter upregulation mediates resistance to the CDK7 inhibitors THZ1 and ICEC0942

The CDK7 inhibitors (CDK7i) ICEC0942 and THZ1, are promising new cancer therapeutics. Resistance to targeted drugs frequently compromises cancer treatment. We sought to identify mechanisms by which cancer cells may become resistant to CDK7i. Resistant lines were established through continuous drug selection. ABC-transporter copy number, expression and activity were examined using real-time PCR, immunoblotting and flow cytometry. Drug responses were measured using growth assays. ABCB1 was upregulated in ICEC0942-resistant cells and there was cross-resistance to THZ1. THZ1-resistant cells upregulated ABCG2 but remained sensitive to ICEC0942. Drug resistance in both cell lines was reversible upon inhibition of ABC-transporters. CDK7i response was altered in adriamycin- and mitoxantrone-resistant cell lines demonstrating ABC-transporter upregulation. ABCB1 expression correlated with ICEC0942 and THZ1 response, and ABCG2 expression with THZ2 response, in a panel of cancer cell lines. We have identified ABCB1 upregulation as a common mechanism of resistance to ICEC0942 and THZ1, and confirmed that ABCG2 upregulation is a mechanism of resistance to THZ1. The identification of potential mechanisms of CDK7i resistance and differences in susceptibility of ICEC0942 and THZ1 to ABC-transporters, may help guide their future clinical use.

Copper(i)-catalysed azide–alkyne cycloaddition and antiproliferative activity of mono- and bis-1,2,3-triazole derivatives

A series of mono- and bis-1,2,3-triazole derivatives were prepared via the copper(i)-catalysed azide–alkyne cycloaddition between substituted aromatic derivatives, comprising one or two terminal alkyne groups and a selection of aromatic azides.

Plant defensin PvD1 modulates the membrane composition of breast tumour-derived exosomes

One of the most important causes of failure in tumour treatment is the development of resistance to therapy. Cancer cells can develop the ability to lose sensitivity to anti-neoplastic drugs during reciprocal crosstalk between cells and their interaction with the tumour microenvironment (TME). Cell-to-cell communication regulates a cascade of interdependent events essential for disease development and progression and can be mediated by several signalling pathways. Exosome-mediated communication is one of the pathways regulating these events. Tumour-derived exosomes (TDE) are believed to have the ability to modulate TMEs and participate in multidrug resistance mechanisms. In this work, we studied the effect of the natural defensin from common bean, PvD₁, on the formation of exosomes by breast cancer MCF-7 cells, mainly the modulatory effect it has on the level of CD63 and CD9 tetraspanins. Moreover, we followed the interaction of PvD₁ with biological and model membranes of selected composition, by biophysical and imaging techniques. Overall, the results show that PvD₁ induces a dual effect on MCF-7 derived exosomes: the peptide attenuates the recruitment of CD63 and CD9 to exosomes intracellularly and binds to the mature exosomes in the extracellular environment. This work uncovers the exosome-mediated anticancer action of PvD₁, a potential nutraceutical agent.

Dissecting multi drug resistance in head and neck cancer cells using multicellular tumor spheroids

One of the hallmarks of cancers is their ability to develop resistance against therapeutic agents. Therefore, developing effective in vitro strategies to identify drug resistance remains of paramount importance for successful treatment. One of the ways cancer cells achieve drug resistance is through the expression of efflux pumps that actively pump drugs out of the cells. To date, several studies have investigated the potential of using 3-dimensional (3D) multicellular tumor spheroids (MCSs) to assess drug resistance; however, a unified system that uses MCSs to differentiate between multi drug resistance (MDR) and non-MDR cells does not yet exist. In the present report we describe MCSs obtained from post-diagnosed, pre-treated patient-derived (PTPD) cell lines from head and neck squamous cancer cells (HNSCC) that often develop resistance to therapy. We employed an integrated approach combining response to clinical drugs and screening cytotoxicity, monitoring real-time drug uptake, and assessing transporter activity using flow cytometry in the presence and absence of their respective specific inhibitors. The report shows a comparative response to MDR, drug efflux capability and reactive oxygen species (ROS) activity to assess the resistance profile of PTPD MCSs and two-dimensional (2D) monolayer cultures of the same set of cell lines. We show that MCSs provide a robust and reliable in vitro model to evaluate clinical relevance. Our proposed strategy can also be clinically applicable for profiling drug resistance in cancers with unknown resistance profiles, which consequently can indicate benefit from downstream therapy.

Let-7a Could Serve as A Biomarker for Chemo-Responsiveness to Docetaxel in Gastric Cancer

BACKGROUND

MicroRNAs are noncoding RNAs which play critical roles in response to anti-cancer agents. Let-7a and miR-21 are well-known tumor-suppressor and oncomiR miRNAs, respectively. They are involved in tumorigenesis of gastric cancer and have potential to be used as markers in response to the therapy.

OBJECTIVE

We aimed to study alterations in the expression of Let-7a and miR-21, and their targets in gastric cancer cell lines after treatment with docetaxel.

METHODS

In order to determine the IC50 of docetaxel, MTT assay was performed in AGS, MKN45 and KATO III gastric cancer cell lines. The expression levels of Let-7a and miR-21 and their target genes, HMGA2 and PDCD4, were determined by reverse-transcription quantitative real-time PCR for both treated and untreated cell lines.

RESULTS

MTT assay showed higher IC50 concentration of docetaxel in KATO III in comparison with AGS and MKN45, indicating KATO III`s higher resistance to docetaxel. Following the treatment, the expression level of Let-7a was significantly increased in AGS and MKN45, while decreased in KATO III. Expression level of miR- 21 in the three treated cell lines was increased significantly. Not only Let-7a, but also expression level of HMGA2 and PDCD4 genes showed different patterns in KATO III in comparison with AGS and MKN45.

CONCLUSION

Down-regulation and up-regulation of Let-7a in docetaxel-resistant and sensitive cell lines, respectively indicates its potential usefulness as biomarker for responsiveness of gastric cancer to the therapy with docetaxel and also for predicting patient`s outcome.

RNA-based therapeutics for colorectal cancer: Updates and future directions

Colorectal cancer (CRC) is one of the most common causes of cancer death worldwide. While standard chemotherapy and new targeted therapy have been improved recently, problems such as multidrug resistance (MDR) and severe side effects remain unresolved. RNAs are essential to all biological processes including cell proliferation and differentiation, cell cycle, apoptosis, activation of tumor suppressor genes, suppression of oncogenes. Therefore, there are various potential approaches to address genetic disease like CRC at the RNA level. In contrast to conventional treatments, RNA-based therapeutics such as RNA interference, antisense oligonucleotides, RNA aptamer, ribozymes, have the advantages of high specificity, high potency and low toxicity. It has gained more and more attention due to the flexibility in modulating a wide range of targets. Here, we highlight recent advances and clinical studies involving RNA-based therapeutics and CRC. We also discuss their advantages and limitations that remain to be overcome for the treatment of human CRC.

Emerging Functions of Human IFIT Proteins in Cancer

Interferon-induced protein with tetratricopeptide repeats (IFIT) genes are prominent interferon-stimulated genes (ISGs). The human IFIT gene family consists of four genes named IFIT1, IFIT2, IFIT3, and IFIT5. The expression of IFIT genes is very low in most cell types, whereas their expression is greatly enhanced by interferon treatment, viral infection, and pathogen-associated molecular patterns (PAMPs). The proteins encoded by IFIT genes have multiple tetratricopeptide repeat (TPR) motifs. IFIT proteins do not have any known enzymatic roles. However, they execute a variety of cellular functions by mediating protein-protein interactions and forming multiprotein complexes with cellular and viral proteins through their multiple TPR motifs. The versatile tertiary structure of TPR motifs in IFIT proteins enables them to be involved in distinct biological functions, including host innate immunity, antiviral immune response, virus-induced translation initiation, replication, double-stranded RNA signaling, and PAMP recognition. The current understanding of the IFIT proteins and their role in cellular signaling mechanisms is limited to the antiviral immune response and innate immunity. However, recent studies on IFIT protein functions and their involvement in various molecular signaling mechanisms have implicated them in cancer progression and metastasis. In this article, we focused on critical molecular, biological and oncogenic functions of human IFIT proteins by reviewing their prognostic significance in health and cancer. Research suggests that IFIT proteins could be novel therapeutic targets for cancer therapy.

Nanostructured Systems in Advanced Drug Targeting for the Cancer Treatment: Recent Patents

BACKGROUND

Cancer is one of the leading causes of death in the world and it is necessary to develop new strategies for its treatment because most therapies have limited access to many types of tumors, as well as low therapeutic efficacy and high toxicity.

OBJECTIVE

The present research aims to identify recent patents of drug delivery nanostructured systems that may have application in improving cancer treatment.

METHODS

Recent patents regarding the drug delivery nanostructured systems for cancer treatment were obtained from the patent databases of the six main patent offices of the world: United States Patent and Trademark Office, European Patent Office, World Intellectual Property Organization, Japan Patent Office, State Intellectual Property Office of China and Korean Intellectual Property Office.

RESULTS

A total of 1710 patent documents from 1998 to 2017 including "drug delivery nanostructured systems for cancer treatment" were retrieved. The top five countries in patent share were USA, China, South Korea, Canada and Germany. The universities and enterprises of USA had the highest amount of patents followed by institutions from China.

CONCLUSION

There is a strong tendency for the development of new nanostructured systems for the release of drugs; particularly, in recent years, the development of nanoparticles has focused on nanodiscs, gold nanoparticles and immunoliposomes.

Chemoprevention of Colorectal Cancer by Anthocyanidins and Mitigation of Metabolic Shifts Induced by Dysbiosis of the Gut Microbiome

Diets rich in fat, smoking, as well as exposure to environmental pollutants and dysbiosis of gut microbiota, increase the risk of developing colorectal cancer. Much progress has been made in combating colorectal cancer. However, options for chemoprevention from environmental insult and dysbiosis of gut microbiota remain elusive. We investigated the influence of berry-derived anthocyanidins (Anthos), with and without encapsulating them in bovine milk-derived exosomes (ExoAnthos), on the chemoprevention of bacteria-driven colon tumor development. Anthos and ExoAnthos treatment of colon cancer cells showed dose-dependent decreases in cell viability. Calculated selectivity index (SI) values for Anthos and ExoAnthos suggest that both treatments selectively targeted cancer over normal colon cells. In addition, ExoAnthos treatment yielded higher SI values than Anthos. Anthos and ExoAnthos treatment of Apc^Min/+ mice inoculated with enterotoxigenic Bacteriodes fragilis (ETBF) bacteria led to significant decreases in colon tumor numbers over mice receiving vehicle treatments. Western blot analysis of normal colon, colon tumor, and liver tissue lysates showed that mice inoculated with ETBF featured increased expression of phase I enzymes in normal colon tissue and decreased expression of phase II enzymes in liver tissue. Treatment with the Anthos and ExoAnthos reverted the modulation of phase I and phase II enzymes, respectively; no significant changes in phase II enzyme expression occurred in colon tumor tissue. Treatment of HCT-116 cells with the ubiquitous carcinogen, benzo[a]pyrene (B[a]P) led to similar modulation of phase I and II enzymes, which was partially mitigated by treatment with Anthos. These results provide a promising outlook on the impact of berry Anthos for prevention and treatment of bacteria- and B[a]P-driven colorectal cancer.

The pro-tumorigenic host response to cancer therapies

Resistance to cancer therapy remains a major challenge in clinical oncology. Although the initial treatment phase is often successful, eventual resistance, characterized by tumour relapse or spread, is discouraging. The majority of studies devoted to investigating the basis of resistance have focused on tumour-related changes that contribute to therapy resistance and tumour aggressiveness. However, over the last decade, the diverse roles of various host cells in promoting therapy resistance have become more appreciated. A growing body of evidence demonstrates that cancer therapy can induce host-mediated local and systemic responses, many of which shift the delicate balance within the tumour microenvironment, ultimately facilitating or supporting tumour progression. In this Review, recent advances in understanding how the host response to different cancer therapies may promote therapy resistance are discussed, with a focus on therapy-induced immunological, angiogenic and metastatic effects. Also summarized is the potential of evaluating the host response to cancer therapy in an era of precision medicine in oncology.

5-fluorouracil and other fluoropyrimidines in colorectal cancer: Past, present and future

5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for colorectal cancer (CRC) in the palliative and adjuvant settings. Over the past four decades, several modulation strategies including the implementation of 5-FU-based combination regimens and 5-FU pro-drugs have been developed and tested to increase the anti-tumor activity of 5-FU and to overcome the clinical resistance. Despite the encouraging progress in CRC therapy to date, the patients' response rates to therapy continue to remain low and the patients' benefit from 5-FU-based therapy is frequently compromised by the development of chemoresistance. Inter-individual differences in the treatment response in CRC patients may originate in the unique genetic and epigenetic make-up of each individual. The critical element in the current trend of personalized medicine is the proper comprehension of causes and mechanisms contributing to the low or lack of sensitivity of tumor tissue to 5-FU-based therapy. The identification and validation of predictive biomarkers for existing 5-FU-based and new targeted therapies for CRC treatment will likely improve patients' outcomes in the future. Herein we present a comprehensive review summarizing options of CRC treatment and the mechanisms of 5-FU action at the molecular level, including both anabolic and catabolic ways. The main part of this review comprises the currently known molecular mechanisms underlying the chemoresistance in CRC patients. We also focus on various 5-FU pro-drugs developed to increase the amount of circulating 5-FU and to limit toxicity. Finally, we propose future directions of personalized CRC therapy according to the latest published evidence.

Targeting Integrins in Cancer Nanomedicine: Applications in Cancer Diagnosis and Therapy

Due to advancements in nanotechnology, the application of nanosized materials (nanomaterials) in cancer diagnostics and therapeutics has become a leading area in cancer research. The decoration of nanomaterial surfaces with biological ligands is a major strategy for directing the actions of nanomaterials specifically to cancer cells. These ligands can bind to specific receptors on the cell surface and enable nanomaterials to actively target cancer cells. Integrins are one of the cell surface receptors that regulate the communication between cells and their microenvironment. Several integrins are overexpressed in many types of cancer cells and the tumor microvasculature and function in the mediation of various cellular events. Therefore, the surface modification of nanomaterials with integrin-specific ligands not only increases their binding affinity to cancer cells but also enhances the cellular uptake of nanomaterials through the intracellular trafficking of integrins. Moreover, the integrin-specific ligands themselves interfere with cancer migration and invasion by interacting with integrins, and this finding provides a novel direction for new treatment approaches in cancer nanomedicine. This article reviews the integrin-specific ligands that have been used in cancer nanomedicine and provides an overview of the recent progress in cancer diagnostics and therapeutic strategies involving the use of integrin-targeted nanomaterials.

Application of Computational Biology and Artificial Intelligence Technologies in Cancer Precision Drug Discovery

Artificial intelligence (AI) proves to have enormous potential in many areas of healthcare including research and chemical discoveries. Using large amounts of aggregated data, the AI can discover and learn further transforming these data into "usable" knowledge. Being well aware of this, the world's leading pharmaceutical companies have already begun to use artificial intelligence to improve their research regarding new drugs. The goal is to exploit modern computational biology and machine learning systems to predict the molecular behaviour and the likelihood of getting a useful drug, thus saving time and money on unnecessary tests. Clinical studies, electronic medical records, high-resolution medical images, and genomic profiles can be used as resources to aid drug development. Pharmaceutical and medical researchers have extensive data sets that can be analyzed by strong AI systems. This review focused on how computational biology and artificial intelligence technologies can be implemented by integrating the knowledge of cancer drugs, drug resistance, next-generation sequencing, genetic variants, and structural biology in the cancer precision drug discovery.

MicroRNA-152 suppresses cisplatin resistance in A549 cells

The present study aimed to investigate the association between microRNA-152 and cisplatin resistance in non-small cell lung cancer. A549 and cisplatin-resistant A549 cells (A549/cis) were maintained in vitro. Reverse transcription-quantitative PCR (RT-qPCR) was performed to analyze differences in microRNA-152 levels between A549 and A549/cis cells, and changes in Bcl-2 and NF-κB expression levels were analyzed via RT-qPCR and western blot analyses. MicroRNA-152 was overexpressed in A549/cis cells via transfection of a microRNA-152 mimic. Upon treating transfected or untransfected A549/cis cells with 2 µg/l cisplatin for 24 h, a Cell Counting Kit-8 assay, morphological analysis and flow cytometry analysis were performed to evaluate the effect of microRNA-152 on the inhibition of cell proliferation and induction of apoptosis. Furthermore, changes in Bcl-2 and NF-κB expression levels in microRNA-152-overexpressing A549/cis cells were also analyzed. MicroRNA-152 was significantly downregulated and Bcl-2 and NF-κB were significantly upregulated in A549/cis cells (P<0.05). MicroRNA-152 upregulation enhanced the inhibitory effect of cisplatin on A549/cis cells. These results suggest that microRNA-152 downregulates Bcl-2 and NF-κB. MicroRNA-152 downregulation may induce cisplatin resistance in non-small cell lung cancer cells, whereas microRNA-152 upregulation may improve cisplatin sensitivity among A549/cis cells via downregulation of Bcl-2 and NF-κB.

Comprehensive bioinformatics study reveals targets and molecular mechanism of hesperetin in overcoming breast cancer chemoresistance

The effectiveness of chemotherapy in breast cancer treatment can be increased using a combinatorial agent. Hesperetin has been reported to increase the sensitivity of doxorubicin in breast cancer cells; however, the underlying molecular mechanism remains unclear. This present study was conducted to identify the potential target and molecular mechanism of hesperetin in circumventing breast cancer chemoresistance using a bioinformatics approach. Microarray data obtained after hesperetin treatment in the NCI-60 cell line panel collection were retrieved from the COMPARE public library. These data were then compared with the list of the regulatory genes of breast cancer resistance obtained from PubMed and further analyzed for gene ontology and KEGG pathway enrichment, as well as protein-protein interaction network. A Venn diagram of COMPARE microarray data and the gene list from PubMed generated 56 genes (potential therapeutic target genes/PTTGs). These PTTGs participate in the biological process of the JAK-STAT cascade and are located in the nucleus, exert a molecular function in protein serine/threonine kinase activity, and regulate the erbB signaling pathway. Drug association analysis demonstrated that both hesperetin and the erbB receptor inhibitors, i.e., monoclonal antibody and tyrosine kinase inhibitor, target the same mRNA expression. Furthermore, results of the molecular docking study revealed that hesperetin is a promising inhibitor that targets ABL1, DNMT3B, and MLH1 due to the similarity of binding properties with its native ligand. In conclusion, the possible pathways and the regulatory genes identified in this study may offer new insights into the mechanism by which hesperetin overcomes breast cancer chemoresistance. A combinatorial therapy with hesperetin targeting ABL1, DNMT3B, and MLH1 may be effective in circumventing chemoresistance in breast cancer.

Extracellular vesicles as a novel source of biomarkers in liquid biopsies for monitoring cancer progression and drug resistance

Cancer-derived extracellular vesicles (EVs) have been detected in the bloodstream and other biofluids of cancer patients. They carry various tumor-derived molecules such as mutated DNA and RNA fragments, oncoproteins as well as miRNA and protein signatures associated with various phenotypes. The molecular cargo of EVs partially reflects the intracellular status of their cellular origin, however various sorting mechanisms lead to the enrichment or depletion of EVs in specific nucleic acids, proteins or lipids. It is becoming increasingly clear that cancer-derived EVs act in a paracrine and systemic manner to promote cancer progression by transferring aggressive phenotypic traits and drug-resistant phenotypes to other cancer cells, modulating the anti-tumor immune response, as well as contributing to remodeling the tumor microenvironment and formation of pre-metastatic niches. These findings have raised the idea that cancer-derived EVs may serve as analytes in liquid biopsies for real-time monitoring of tumor burden and drug resistance. In this review, we have summarized recent longitudinal clinical studies describing promising EV-associated biomarkers for cancer progression and tracking cancer evolution as well as pre-clinical and clinical evidence on the relevance of EVs for monitoring the emergence or progression of drug resistance. Furthermore, we outlined the state-of-the-art in the development and commercialization of EV-based biomarkers and discussed the scientific and technological challenges that need to be met in order to translate EV research into clinically applicable tools for precision medicine.

Emergent Nanotechnological Strategies for Systemic Chemotherapy against Melanoma

Melanoma is an aggressive form of skin cancer, being one of the deadliest cancers in the world. The current treatment options involve surgery, radiotherapy, targeted therapy, immunotherapy and the use of chemotherapeutic agents. Although the last approach is the most used, the high toxicity and the lack of efficacy in advanced stages of the disease have demanded the search for novel bioactive molecules and/or efficient drug delivery systems. The current review aims to discuss the most recent advances on the elucidation of potential targets for melanoma treatment, such as aquaporin-3 and tyrosinase. In addition, the role of nanotechnology as a valuable strategy to effectively deliver selective drugs is emphasized, either incorporating/encapsulating synthetic molecules or natural-derived compounds in lipid-based nanosystems such as liposomes. Nanoformulated compounds have been explored for their improved anticancer activity against melanoma and promising results have been obtained. Indeed, they displayed improved physicochemical properties and higher accumulation in tumoral tissues, which potentiated the efficacy of the compounds in pre-clinical experiments. Overall, these experiments opened new doors for the discovery and development of more effective drug formulations for melanoma treatment.

Major obstacles to doxorubicin therapy: Cardiotoxicity and drug resistance

Background

Doxorubicin is one of the most commonly prescribed and time-tested anticancer drugs. Although being considered as a first line drug in different types of cancers, the two main obstacles to doxorubicin therapy are drug-induced cardiotoxicity and drug resistance.

Method

The study utilizes systemic reviews on publications of previous studies obtained from scholarly journal databases including PubMed, Medline, Ebsco Host, Google Scholar, and Cochrane. The study utilizes secondary information obtained from health organizations using filters and keywords to sustain information relevancy. The study utilizes information retrieved from studies captured in the peer-reviewed journals on “doxorubicin-induced cardiotoxicity” and “doxorubicin resistance.”

Discussion and results

The exact mechanisms of cardiotoxicity are not known; various hypotheses are studied. Doxorubicin can lead to free radical generation in various ways. The commonly proposed underlying mechanisms promoting doxorubicin resistance are the expression of multidrug resistance proteins as well as other causes.

Conclusion

In this review, we have described the major obstacles to doxorubicin therapy, doxorubicin-induced cardiotoxicity as well as the mechanisms of cancer drug resistance and in following the treatment failures.

Inflammation, immunosuppressive microenvironment and breast cancer: opportunities for cancer prevention and therapy

Breast cancer is the most commonly diagnosed malignancy and a leading cause of cancer-related death in women worldwide. It also exhibits pronounced racial disparities in terms of incidence and clinical outcomes. There has been a growing interest in research community to better understand the role of the microenvironment in cancer. Several lines of evidence have highlighted the significance of chronic inflammation at the local and/or systemic level in breast tumor pathobiology. Inflammation can influence breast cancer progression, metastasis and therapeutic outcome by establishing a tumor supportive immune microenvironment. These processes are mediated through a variety of cytokines and hormones that exert their biological actions either locally or distantly via systemic circulation. Targeting of immune and inflammatory pathways has met tremendous success in some cancers underscoring the importance of research to further our understanding of these systems in breast cancer. This knowledge can be helpful not only in the development of novel prevention and therapeutic strategies, but also help in better prediction of therapeutic responses in patients. This review summarizes some of the significant findings on the role of inflammation in breast cancer to gain collective molecular and mechanistic insights. We also discuss ongoing efforts and future outlook to exploit the existing knowledge for improved breast cancer management.

LY2228820 induces synergistic anti-cancer effects with anti-microtubule chemotherapeutic agents independent of P-glycoprotein in multidrug resistant cancer cells

Side-effects and resistance substantially limit the efficacy of chemotherapy. One possible solution to this persistent problem would be co-administration of targeted therapy and chemotherapy to achieve synergistic anti-cancer effects without extra toxicity. Here, we reported that LY2228820, a selective inhibitor of p38-MAPK signaling pathway, could induce synergistic anti-cancer effects with anti-microtubule (AMT) chemotherapy both in vitro and in vivo. In drug-resistant cancer cells, treatment with either LY2228820 or AMT drug alone was compatible with viability, while co-administration of both led to dramatic cytotoxicity, G2/M arrest and apoptosis. Moreover, co-treatment with LY2228820 notably improved the effectiveness of paclitaxel without exhibiting adverse effects in vivo. Mechanistic studies showed that LY2228820 sensitized cancer cells to AMT agents independent of P-gp. LY2228820 did not influence either the expression or the function of P-gp. Instead, it could inhibit p38-HSP27 signaling axis by down-regulating p-HSP27. Furthermore, LY2228820 blocked the p-HSP27 mediated protective response against AMT drugs in tumor cells, resulting in mitochondrial instability and the activation of mitochondrial death pathways. This P-gp-independent regime containing LY2228820 and AMT agents could produce synergistic anti-cancer effects without extra systematic toxicity. Our study offers a novel strategy for improving the therapeutic efficacy of AMT drugs by achieving a better balance between efficacy and toxicity. This new combination regime could be advantageous in patients who show little response to the maximal dosage of AMT chemotherapy, as well as those unable to tolerate the systematic toxicity of these agents in clinic.

CD155 downregulation synergizes with adriamycin to induce breast cancer cell apoptosis

CD155 has been implicated in migration, invasion, proliferation and apoptosis of human cancer cells, and DNA damage response caused by chemotherapeutic agents or reactive oxygen species has been shown to attribute to CD155 induction. Adriamycin (Adr) is one of the most common chemotherapeutic drugs used to treat breast cancer. Here we reported that treatment with Adr upregulated CD155 expression on several in vitro cultured breast cancer cells and in breast cancer cell 4T1 xenografts. We also found that CD155 knockdown or Adr treatment induced apoptosis of in vitro cultured cancer cells and cancer cells in 4T1 xenografts, and a combination of CD155 knockdown with Adr treatment induced more cell death than either of them. Furthermore, we revealed that the combination of CD155 knockdown with Adr treatment suppressed the growth of 4T1 xenografts more significantly than them alone. In summary, our results demonstrate that CD155 downregulation synergizes with Adr to induce breast cancer cell apoptosis, thereby to suppress tumor growth. Our results also suggest that CD155 upregulation may be a mechanism underlying Adr resistance by breast cancer cells.

Neuromedin U: A Small Peptide in the Big World of Cancer

Neuromedin U (NMU), a neuropeptide isolated from porcine spinal cord and named because of its activity as a rat uterus smooth muscle contraction inducer, is emerging as a new player in the tumorigenesis and/or metastasis of many types of cancers. Expressed in a variety of tissues, NMU has been shown to possess many important activities in the central nervous system as well as on the periphery. Along with the main structural and functional features of NMU and its currently known receptors, we summarized a growing number of recently published data from different tissues and cells that associate NMU activity with cancer development and progression. We ask if, based on current reports, NMU can be included as a marker of these processes and/or considered as a therapeutic target.

Intercellular Crosstalk Via Extracellular Vesicles in Tumor Milieu as Emerging Therapies for Cancer Progression

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Increasing evidence has suggested that extracellular vesicles (EV) mediated bidirectional transfer of functional molecules (such as proteins, different types of RNA, and lipids) between cancer cells and tumor stromal cells (immune cells, endothelial cells, fibroblasts, stem cells) and strongly contributed to the reinforcement of cancer progression. Thus, intercellular EV-mediated signaling in tumor microenvironment (TME) is essential in the modulation of all processes that support and promote tumor development like immune suppression, angiogenesis, invasion and metastasis, and resistance of tumor cells to anticancer treatments.

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Besides EV potential to revolutionize our understanding of the cancer cell-stromal cells crosstalk in TME, their ability to selectively transfer different cargos to recipient cells has created excitement in the field of tumortargeted delivery of specific molecules for anticancer treatments. Therefore, in tight connection with previous findings, this review brought insight into the dual role of EV in modulation of TME. Thus, on one side EV create a favorable phenotype of tumor stromal cells for tumor progression; however, as a future new class of anticancer drug delivery systems EV could re-educate the TME to overcome main supportive processes for malignancy progression.

Tumor-Targeted Drug Conjugates as an Emerging Novel Therapeutic Approach in Small Cell Lung Cancer (SCLC)

There are few effective therapies for small cell lung cancer (SCLC), a highly aggressive disease representing 15% of total lung cancers. With median survival <2 years, SCLC is one of the most lethal cancers. At present, chemotherapies and radiation therapy are commonly used for SCLC management. Few protein-targeted therapies have shown efficacy in improving overall survival; immune checkpoint inhibitors (ICIs) are promising agents, but many SCLC tumors do not express ICI targets such as PD-L1. This article presents an alternative approach to the treatment of SCLC: the use of drug conjugates, where a targeting moiety concentrates otherwise toxic agents in the vicinity of tumors, maximizing the differential between tumor killing and the cytotoxicity of normal tissues. Several tumor-targeted drug conjugate delivery systems exist and are currently being actively tested in the setting of SCLC. These include antibody-drug conjugates (ADCs), radioimmunoconjugates (RICs), small molecule-drug conjugates (SMDCs), and polymer-drug conjugates (PDCs). We summarize the basis of action for these targeting compounds, discussing principles of construction and providing examples of effective versus ineffective compounds, as established by preclinical and clinical testing. Such agents may offer new therapeutic options for the clinical management of this challenging disease in the future.

miR-142-3p is a tumor suppressor that inhibits estrogen receptor expression in ER-positive breast cancer

Estrogen receptors (ERs) are involved in the development of many types of malignant tumors, in particular, breast cancer. Among others, ERs affect cell growth, proliferation, and differentiation. The microRNA (miRNA) miR-142-3p has been shown to inhibit carcinogenesis by regulating various cellular processes, including cell cycle progression, cell migration, apoptosis, and invasion. It does so via targeting molecules involved in a range of signaling pathways. We surgically collected 20 ER-positive breast cancer samples, each with matched adjacent normal breast tissue, and measured the expression of miR-142-3p via quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics methods, luciferase reporter assay, qRT-PCR, and western blot analysis were used to assess whether miR-142-3p could target ESR1, which encodes the estrogen receptor, in ER-positive breast cancer cells and patient samples. We also restored miRNA expression and performed cell viability, cytotoxicity, and colony formation assays. Western blot analysis and qRT-PCR were used to study the expression of apoptosis and stemness markers. We found that miR-142-3p is downregulated in ER-positive breast cancers. Restoration of miR-142-3p expression in ER-positive breast cancer cells reduced cell viability, induced apoptosis via the intrinsic pathway and decreased both colony formation and the expression of stem cell markers. Bioinformatic analysis predicted miR-142-3p could bind to 3'-untranslated region ESR1 messenger RNA (mRNA). Consistently, we demonstrated that miR-142-3p reduced luciferase activity in ER-positive breast cancer cells, and decreased ESR1 expression in both mRNA and protein levels. The results revealed miR-142-3p and ESR1 expression correlated negatively in ER-positive breast cancer samples. The results suggest miR-142-3p acts as a tumor suppressor via multiple mechanisms. Thus, restoration of miR-142-3p expression, for example, via miRNA replacement therapy, may represent an effective strategy for the treatment of ER-positive breast cancer patients.

Long Non-Coding RNA in the Pathogenesis of Cancers

The incidence and mortality rate of cancer has been quickly increasing in the past decades. At present, cancer has become the leading cause of death worldwide. Most of the cancers cannot be effectively diagnosed at the early stage. Although there are multiple therapeutic treatments, including surgery, radiotherapy, chemotherapy, and targeted drugs, their effectiveness is still limited. The overall survival rate of malignant cancers is still low. It is necessary to further study the mechanisms for malignant cancers, and explore new biomarkers and targets that are more sensitive and effective for early diagnosis, treatment, and prognosis of cancers than traditional biomarkers and methods. Long non-coding RNAs (lncRNAs) are a class of RNA transcripts with a length greater than 200 nucleotides. Generally, lncRNAs are not capable of encoding proteins or peptides. LncRNAs exert diverse biological functions by regulating gene expressions and functions at transcriptional, translational, and post-translational levels. In the past decade, it has been demonstrated that the dysregulated lncRNA profile is widely involved in the pathogenesis of many diseases, including cancer, metabolic disorders, and cardiovascular diseases. In particular, lncRNAs have been revealed to play an important role in tumor growth and metastasis. Many lncRNAs have been shown to be potential biomarkers and targets for the diagnosis and treatment of cancers. This review aims to briefly discuss the latest findings regarding the roles and mechanisms of some important lncRNAs in the pathogenesis of certain malignant cancers, including lung, breast, liver, and colorectal cancers, as well as hematological malignancies and neuroblastoma.

Highlights in Resistance Mechanism Pathways for Combination Therapy

Combination chemotherapy has been a mainstay in cancer treatment for the last 60 years. Although the mechanisms of action and signaling pathways affected by most treatments with single antineoplastic agents might be relatively well understood, most combinations remain poorly understood. This review presents the most common alterations of signaling pathways in response to cytotoxic and targeted anticancer drug treatments, with a discussion of how the knowledge of signaling pathways might support and orient the development of innovative strategies for anticancer combination therapy. The ultimate goal is to highlight possible strategies of chemotherapy combinations based on the signaling pathways associated with the resistance mechanisms against anticancer drugs to maximize the selective induction of cancer cell death. We consider this review an extensive compilation of updated known information on chemotherapy resistance mechanisms to promote new combination therapies to be to discussed and tested.

Epigenetic reprogramming and potential application of epigenetic-modifying drugs in acquired chemotherapeutic resistance

Chemotherapy is the most common clinical choice of treatment for cancer, however, acquired chemoresistance is a major challenge that limits the successful outcome of this option. Systematic review of in vitro, in vivo, preclinical and clinical studies suggests that acquired chemoresistance is polygenic, progressive, and involve both genetic and epigenetic heterogeneities and perturbations. Various mechanisms that confer resistance to chemotherapy are tightly controlled by epigenetic regulations. Poised epigenetic plasticity and temporal increase in epigenetic alterations upon chemotherapy make chemoresistance likely an epigenetic-driven process. The transient and reversible nature of epigenetic modulations enable ways to intervene the epigenetic re-programing associated with acquired chemoresistance via application of epigenetic modifying drugs. This review discusses recent understandings behind the various mechanisms of acquired chemoresistance that are under the control of epigenetic drivers, potential application of epigenetic-based drugs in resensitizing refractory cancers to chemotherapy, the limitations and future scope for clinical application of epigenetic therapeutics in successfully addressing chemoresistance.

Fucoidan-coated coral-like Pt nanoparticles for computed tomography-guided highly enhanced synergistic anticancer effect against drug-resistant breast cancer cells

Chemotherapy, the most commonly applied cancer treatment, often causes unexpected failure due to multidrug resistance (MDR). To overcome MDR, we have designed a platform to realize a combinational synergistic effect of a natural bioactive product (fucoidan), anticancer small compound (doxorubicin), and photothermal nanocarrier (Pt nanoparticle) to treat drug-resistant breast cancer cells. Especially, fucoidan, a sulfated, polysaccharide-structured, therapeutic biopolymer, has been recently recognized as a potential anticancer compound; however, its cancer-inhibiting efficacy has been regarded as low owing to its insufficient level in serum following its conventional oral ingestion. To enhance its potency, fucoidan was applied as a biocompatible surfactant and surface-coating biopolymer in nanocarrier synthesis to manufacture coral-like, fucoidan-coated Pt nanoparticles with a rough surface morphology by a one-pot method. As a result, the biological-thermo-chemo trimodal combination treatment showed excellent therapeutic efficiency against the MDR breast cancer cell MCF-7 ADR both in vitro and in vivo, and the computed tomography contrast effect was also confirmed from the constituent element Pt. Beyond universal application in drug delivery and photothermal therapy, the present approach of applying a MDR modulating/anticancer natural product from nanoparticle synthesis to theranostics will contribute greatly to maximizing their potential through interdisciplinary convergence in the near future.

Adapting and Surviving: Intra and Extra-Cellular Remodeling in Drug-Resistant Gastric Cancer Cells

Despite the significant recent advances in clinical practice, gastric cancer (GC) represents a leading cause of cancer-related deaths in the world. In fact, occurrence of chemo-resistance still remains a daunting hindrance to effectiveness of the current approach to GC therapy. There is accumulating evidence that a plethora of cellular and molecular factors is implicated in drug-induced phenotypical switching of GC cells. Among them, epithelial-mesenchymal transition (EMT), autophagy, drug detoxification, DNA damage response and drug target alterations, have been reported as major determinants. Intriguingly, resistant GC phenotype may be the result of GC cell-induced tumor microenvironment (TME) remodeling, which is currently emerging as a key player in promoting drug resistance and overcoming cytotoxic effects of drugs. In this review, we discuss the possible mechanisms of drug resistance and their involvement in determining current GC therapies failure.

Targeting TRAIL

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2L, has been investigated in the past decade for its promising anticancer activity due to its ability to selectively induce apoptosis in tumoral cells by binding to TRAIL receptors (TRAIL-R). Macromolecules such as agonistic monoclonal antibodies and recombinant TRAIL have not proven efficacious in clinical studies, therefore several small molecules acting as TRAIL-R agonists are emerging in the scientific literature. In this work we focus on systemizing these drug molecules described in the past years, in order to better understand and predict the requirements for a novel anti-tumoral therapy based on the TRAIL-R-induced apoptotic mechanism.

Reduced chemotherapeutic sensitivity in high glucose condition: implication of antioxidant response

Resistance to chemotherapy represents a major obstacle to successful treatment. The generation of reactive oxygen species (ROS) has been directly linked to the cytotoxic effects of several antitumor agents, including Adriamycin (ADR), and modulation of the oxidative balance has been implicated in the development and/or regulation of resistance to chemotherapeutic drugs. We recently showed that high glucose (HG) markedly diminished the cancer cell death induced by anticancer agents such as ADR. In the present study we attempted to evaluate the mechanism that impaired the cytotoxic effect of ADR in HG. We found that, in colon cancer cells, HG attenuated ADR-induced ROS production that consequently diminished ADR-induced H2AX phosphorylation and micronuclei (MN) formation. Mechanistically, HG attenuation of ADR-induced ROS production correlated with increased antioxidant response promoted by NRF2 activity. Thus, pharmacologic inhibition of NRF2 pathway by brusatol re-established the ADR cytotoxic effect impaired by HG. Together, the data provide new insights into chemotherapeutic-resistance mechanisms in HG condition dictated by increased NRF2-induced antioxidant response and how they may be overcome in order to restore chemosensitivity and ADR-induced cell death.

Validation of a sensitive simultaneous LC-MS/MS method for the quantification of novel anti-cancer thiazolidinedione and quinazolin-4-one derivatives in rat plasma and its application in a rat pharmacokinetic study

Thiazolidinediones and quinazolin-4-ones compounds, previously known for their activity against Type 2 diabetes and antifungal activity respectively, are currently being investigated for their anti-cancer activity. The determination of pharmacokinetic parameters for these two classes of compounds using a simultaneous chromatographic method with a low detection limit is a challenge. In this study, a highly sensitive and simultaneous LC-MS/MS-based bioanalytical method was developed and validated in rat plasma for the estimation of four novel anti-cancer compounds, BIT-15-67 and BNT-11, belonging to the Thiazolidinedione class, and BNUA-108 and BNUA-48, from the quinazolin-4-one class. The analytes were extracted from plasma samples by protein precipitation and separated on a short reverse phase Hypersil Phenyl BDS, 50 × 4.6 mm, 2.4 μm column at a column oven temperature of 40 °C. An isocratic mobile phase, a 20:80 (v/v) mixture of 5 mM ammonium acetate solution and acetonitrile containing 0.1% formic acid, was used for the elution at a flow rate of 0.4 mL/min. The analytes and internal standard, sulfaphenazole, were quantified in the multiple reaction monitoring mode using positive electrospray ionization with specific pair of mass by charge ratio. All standard validation parameters were assessed as per current bioanalytical method validation guidelines in rat plasma. The area response for the four analytes was found to be linear over the concentration range of 1.00 to 1000 ng/mL in rat plasma. The signal to noise at LLOQ of 1 ng/mL was adequate for application to different pre-clinical studies. The intra- and inter-day precision were <11% and accuracy deviated -1.8 to 9.60% from the nominal. The mean recovery was high (about 90%) and consistent for all the analytes over the linear dynamic range of the method. This simple, robust and validated method can be employed to determine the rat plasma concentrations of the four selected anticancer compounds in preclinical studies such as the pharmacodynamic and the pharmacokinetic studies including tissue distribution and excretion, and the toxicokinetic studies. In this study, pharmacokinetic parameters were determined using this method for all the four compounds individually following intravenous administration in rats.

Thermal-Responsive Carbon Monoxide (CO) Delivery Expedites Metabolic Exhaustion of Cancer Cells toward Reversal of Chemotherapy Resistance

Multidrug resistance (MDR) is the main cause of chemotherapy failure, and the mechanism of MDR is largely associated with drug efflux mediated by the adenosine triphosphate (ATP)-binding cassette transporters. Herein, an NIR-light-triggered CO release system based on mesoporous Prussian blue nanoparticles (PB NPs) was developed to reverse MDR via CO-induced metabolic exhaustion. Pentacarbonyl iron (Fe(CO)₅) as the CO producer was coupled to PB NPs via coordination interaction, and doxorubicin (Dox) was encapsulated into the pores of PB NPs. After layer-by-layer (LBL) coating, the NPs showed desired serum stability to enhance tumor accumulation. Upon tumor-site-specific NIR light (808 nm) irradiation, the nonlethal temperature elevation cleaved the Fe-CO bond to release CO. CO then expedited mitochondrial metabolic exhaustion to block ATP synthesis and inhibit ATP-dependent drug efflux, thus reversing MDR of the Dox-resistant MCF-7/ADR tumors to potentiate the anticancer efficacy of Dox. In the meantime, CO-mediated mitochondrial exhaustion could upregulate the proapoptotic protein, caspase 3, thus inducing cellular apoptosis and enabling a synergistic anticancer effect with chemotherapy. To the best of our knowledge, this is the first time MDR has been overcome using a CO delivery system. This study provides a promising strategy to realize an effective and safe treatment against MDR tumors and reveals new insights in the use of CO for cancer treatment.

Cancer cell fusion: a potential target to tackle drug-resistant and metastatic cancer cells

Cell fusion is an integral, established phenomenon underlying various physiological processes in the cell cycle. Although research in cancer metastasis has hypothesised numerous molecular mechanisms and signalling pathways responsible for invasion and metastasis, the origin and progression of metastatic cells within primary tumours remains unclear. Recently, the role of cancer cell fusion in cancer metastasis and development of multidrug resistance (MDR) in tumours has gained prominence. However, evidence remains lacking to justify the role of cell fusion in cancer metastasis and drug resistance. Here, we highlight plausible mechanisms governing cell fusion with different cell types in the tumour microenvironment (TME), the clinical relevance of cancer cell fusion, its potential as a target for overcoming MDR and inhibiting metastasis, and putative modes of treatment.

Determinants of nutrient limitation in cancer

Proliferation requires that cells accumulate sufficient biomass to grow and divide. Cancer cells within tumors must acquire a variety of nutrients, and tumor growth slows or stops if necessary metabolites are not obtained in sufficient quantities. Importantly, the metabolic demands of cancer cells can be different from those of untransformed cells, and nutrient accessibility in tumors is different than in many normal tissues. Thus, cancer cell survival and proliferation may be limited by different metabolic factors than those that are necessary to maintain noncancerous cells. Understanding the variables that dictate which nutrients are critical to sustain tumor growth may identify vulnerabilities that could be used to treat cancer. This review examines the various cell-autonomous, local, and systemic factors that determine which nutrients are limiting for tumor growth.

Mutant p53, Stabilized by Its Interplay with HSP90, Activates a Positive Feed-Back Loop Between NRF2 and p62 that Induces Chemo-Resistance to Apigenin in Pancreatic Cancer Cells

Pancreatic cancer is one of the most aggressive cancers whose prognosis is worsened by the poor response to the current chemotherapies. In this study, we investigated the cytotoxic effect of Apigenin, against two pancreatic cell lines, namely Panc1 and PaCa44, harboring different p53 mutations. Apigenin is a flavonoid widely distributed in nature that displays anti-inflammatory and anticancer properties against a variety of cancers. Here we observed that Apigenin exerted a stronger cytotoxic effect against Panc1 cell line in comparison to PaCa44. Searching for mechanisms responsible for such different effect, we found that the higher cytotoxicity of Apigenin correlated with induction of higher level of intracellular ROS, reduction of mutant (mut) p53 and HSP90 expression and mTORC1 inhibition. Interestingly, we found that mutp53 was stabilized by its interplay with HSP90 and activates a positive feed-back loop between NRF2 and p62, up-regulating the antioxidant response and reducing the cytotoxicity of Apigenin. These results suggest that targeting the molecules involved in the mTOR-HSP90-mutp53-p62-NRF2-antioxidant response axis could help to overcome the chemo-resistance of pancreatic cancer to Apigenin.