Emergence Of Drug-resistant Tumor Cells Research Articles

Targeting EphA2: a promising strategy to overcome chemoresistance and drug resistance in cancer.

Erythropoietin-producing hepatocellular A2 (EphA2) is a vital member of the Eph tyrosine kinase receptor family and has been associated with developmental processes. However, it is often overexpressed in tumors and correlates with cancer progression and worse prognosis due to the activation of its noncanonical signaling pathway. Throughout cancer treatment, the emergence of drug-resistant tumor cells is relatively common. Since the early 2000s, researchers have focused on understanding the role of EphA2 in promoting drug resistance in different types of cancer, as well as finding efficient and secure EphA2 inhibitors. In this review, the current knowledge regarding induced resistance by EphA2 in cancer treatment is summarized, and the types of cancer that lead to the most cancer-related deaths are highlighted. Some EphA2 inhibitors were also investigated. Regardless of whether the cancer treatment has reached a drug-resistance stage in EphA2-overexpressing tumors, once EphA2 is involved in cancer progression and aggressiveness, targeting EphA2 is a promising therapeutic strategy, especially in combination with other target-drugs for synergistic effect. For that reason, monoclonal antibodies against EphA2 and inhibitors of this receptor should be investigated for efficacy and drug toxicity.

ROADMAPS: An Online Database of Response Data, Dosing Regimens, and Toxicities of Approved Oncology Drugs as Single Agents to Guide Preclinical In Vivo Studies.

ROADMAPS includes data that can be used to identify tolerable dosing regimens with activity against a variety of human tumors in different mouse strains, providing a resource for planning preclinical studies.

Magnetically switchable mechano-chemotherapy for enhancing the death of tumour cells by overcoming drug-resistance

• A functional mechano-chemotherapeutic nanomaterial DOX-Zn 0.2 Fe 2.8 O 4 –PLGA is successfully synthesized. • A controllable mechano-chemotherapeutic effect that can overcome drug resistance of tumor cells is non-invasively and remotely achieved by means of rotating magnetic field of low intensity (45mT). • A non-invasive and precisely controllable drug-release strategy based on magnetic nanomaterials exposed to a rotating magnetic field of low intensity is demonstrated. • A self-designed Magnetomechanical force generator for mechano-chemotherapy is introduced. • Calculations that shed light on the magnetomechanical force exerted by magnetic nanomaterials onto tumour cell membranes under exposure to a rotating magnetic field are presented. The emergence of drug-resistant tumour cells significantly interferes with the effectiveness of chemotherapeutic treatment plans and represents a major obstacle in the ongoing quest to overcome cancers. Therefore, exploring in detail new therapeutic strategies that can obviate this important challenge is regarded as a very important topic at the time being. Herein, we propose a non-invasive and remotely controllable mechano-chemotherapeutic approach that relies on the use of a rotating magnetic field (RMF) of low intensity (45 m T) in combination with a therapeutic agent consisting of a composite nanomaterial comprised of a poly(lactic-co-glycolic acid) (PLGA) shell co-loaded with Zn 0.2 Fe 2.8 O 4 magnetic nanoparticles (mNPs) and Doxorubicin (DOX). We show that RMF exposure induces a mechanical movement to this nanomaterial, which can be exploited for (i) controllably releasing the anti-cancer drug for chemotherapy, and (ii) promoting the death of tumour cells by means of mechanical forces exerted onto their membranes. Such dual behavior leads to combating cancer cells via different and complementary routes enabling a controllable and efficient therapy. The proposed model enables controllable tumor therapy by precisely operating the magnetic nanomaterials at the nanometer scale, and its applicability is neither restricted to the nanomaterial here demonstrated nor to solely addressing cancer. Modified variants of the proposed model, together with the corresponding therapeutic agents, can be developed to address other pathologies, enabling novel therapeutic approaches that exceed the precision and efficiency of current ones.

Survival and prognostic factors in elderly patients receiving second-line chemotherapy for relapsed small-cell lung cancer: Results from the Japanese Joint Committee of Lung Cancer Registry

ObjectivesMost patients with small-cell lung cancer (SCLC) experience relapse because of the emergence of drug-resistant tumor cells. Therefore, second-line therapy is subsequently required to prolong their survival. However, it is unclear whether second-line chemotherapy can provide a survival benefit to elderly patients with relapsed SCLC. Therefore, this study aimed to evaluate survival and identify prognostic factors in an elderly population. Materials and methodsBased on a nationwide registry database of patients with SCLC (the Japanese Joint Committee of Lung Cancer Registry), we retrospectively reviewed medical records of patients aged ≥ 75 years with relapsed SCLC who subsequently received second-line chemotherapy. Survival time since the initiation of second-line chemotherapy was evaluated. ResultsAmong 731 patients aged ≥ 75 years with SCLC who were accumulated by the nationwide registry database, this study included 228 patients, comprising 190 men and 38 women with a median age of 78 years. The number of patients with performance status (PS) of 0−1 and 2−4 was 196 and 32, respectively. The overall survival (OS) and 1-year survival rates were 7.5 months and 24 %, respectively. A multivariate analysis identified PS, clinical stage at the time of starting first-line therapy, and the interval from the start of first-line therapy to that of second-line therapy as independent prognostic factors. ConclusionThis study with the nationwide registry database showed that among the relapsed elderly SCLC patients who received second-line chemotherapy, a substantial OS may be expected in patients with good PS, at an early clinical stage at the time of starting first-line therapy, and with a longer interval from the start of first-line therapy to that of second-line chemotherapy.

Abstract 4195: β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells through the Cbl-b-EGFR-ERK/Akt signaling pathway

Abstract Background/Aims: β-elemene, a Curcuma wenyujin plant extract, has been widely used as an adjuvant therapeutic agent in cancer treatment. The emergence of drug-resistant tumor cells is defined as multidrug resistance (MDR), and is one of the major ways cancer therapy can fail. Our previous study indicated that, compared to chemo-sensitive human gastric cancer cells, drug-resistant cells have a stronger ability for migration. The aim of this study was to explore the anti-metastasis effects and mechanism of β-elemene in multi-drug resistance human gastric cancer cells. Methods: A cell viability assay was used to assess the resistance of adriamycin-resistant human gastric cancer SGC7901 cells (SGC7901/ADR) and the cytotoxic effects of β-elemene on SGC7901/ADR cells. A wound healing assay and transwell assay were used to explore the anti-metastasis effects of β-elemene. Human matrix metalloproteinase (MMP) antibody array and Western blot analysis were used to explore the potential mechanism. A murine tumor metastasis assay was used to confirm the anti-metastasis effects in vivo. Immunohistochemistry analysis was performed to examine the expressions of related proteins in xenograft tumors. Results: At sub-lethal concentrations (1 μg/ml and 5 μg/ml), β-elemene significantly inhibited cell migration and invasion of SGC7901/ADR cells. The human MMP antibody array indicated that β-elemene could regulate almost all proteins of the MMP family, and changes of MMP-2 and MMP-9 were the most obvious. Western blotting showed an increase of E-cadherin and decrease of vimentin in β-elemene-treated cells. Downregulation of transcription factor ZEB1 and ZEB2 was also detected. Treatment of SGC7901/ADR cells with β-elemene led to downregulation of Akt, ERK, and EGFR phosphorylation, and significant upregulation of the E3 ubiquitin ligase, Cbl-b. Changes of these proteins were confirmed in xenograft tumors. Hematoxylin and eosin staining showed significantly decreased numbers of metastatic tumor colonies in the lungs of nude mice injected with SGC7901/ADR cells and β-elemene compared with those only injected with SGC7901/ADR cells. Conclusions: The results strongly suggest that β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells in vitro and in vivo by regulating the Cbl-b-EGFR-ERK/Akt signaling pathway. β-elemene may be a promising treatment for multidrug resistant human gastric cancer. Citation Format: Ruoxi Yu, Mingming Deng, Huicong Song, Dan Zou, Ling Xu, Xiujuan Qu, Yunpeng Liu, Yuee Teng, Xuejun Hu, Ye Zhang. β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells through the Cbl-b-EGFR-ERK/Akt signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4195.

Acquisition of anticancer drug resistance is partially associated with cancer stemness in human colon cancer cells.

Colorectal cancer (CRC) is one of the most aggressive cancers worldwide. Several anticancer agents are available to treat CRC, but eventually cancer relapse occurs. One major cause of chemotherapy failure is the emergence of drug-resistant tumor cells, suspected to originate from the stem cell compartment. The aim of this study was to ask whether drug resistance was associated with the acquisition of stem cell-like properties. We isolated drug-resistant derivatives of two human CRC cell lines, HT29 and HCT116, using two anticancer drugs with distinct modes of action, oxaliplatin and docetaxel. HT29 cells resistant to oxaliplatin and both HT29 and HCT116 cells resistant to docetaxel were characterized for their expression of genes potentially involved in drug resistance, cell growth and cell division, and by surveying stem cell-like phenotypic traits, including marker genes, the ability to repair cell-wound and to form colonospheres. Among the genes involved in platinum or taxane resistance (MDR1, ABCG2, MRP2 or ATP7B), MDR1 was uniquely overexpressed in all the resistant cells. An increase in the cyclin-dependent kinase inhibitor p21, in cyclinD1 and in CD26, CD166 cancer stem cell markers, was noted in the resistant cells, together with a higher ability to form larger and more abundant colonospheres. However, many phenotypic traits were selectively altered in either HT29- or in HCT116-resistant cells. Expression of EPHB2, ITGβ-1 or Myc was specifically increased in the HT29-resistant cells, whereas only HCT116-resistant cells efficiently repaired cell- wounds. Taken together, our results show that human CRC cells selected for their resistance to anticancer drugs displayed a few stem cell characteristics, a small fraction of which was shared between cell lines. The occurrence of marked phenotypic differences between HT29- and HCT116-drug resistant cells indicates that the acquired resistance depends mostly on the parental cell characteristics, rather than on the drug type used.

Modulation of cell metabolic pathways and oxidative stress signaling contribute to acquired melphalan resistance in multiple myeloma cells.

Alkylating agents are widely used chemotherapeutics in the treatment of many cancers, including leukemia, lymphoma, multiple myeloma, sarcoma, lung, breast and ovarian cancer. Melphalan is the most commonly used chemotherapeutic agent against multiple myeloma. However, despite a 70–80% initial response rate, virtually all patients eventually relapse due to the emergence of drug-resistant tumour cells. By using global proteomic and transcriptomic profiling on melphalan sensitive and resistant RPMI8226 cell lines followed by functional assays, we discovered changes in cellular processes and pathways not previously associated with melphalan resistance in multiple myeloma cells, including a metabolic switch conforming to the Warburg effect (aerobic glycolysis), and an elevated oxidative stress response mediated by VEGF/IL8-signaling. In addition, up-regulated aldo-keto reductase levels of the AKR1C family involved in prostaglandin synthesis contribute to the resistant phenotype. Finally, selected metabolic and oxidative stress response enzymes were targeted by inhibitors, several of which displayed a selective cytotoxicity against the melphalan-resistant cells and should be further explored to elucidate their potential to overcome melphalan resistance.

Stabilizing versus destabilizing the microtubules: a double-edge sword for an effective cancer treatment option?

Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy.

Peripheral T cell lymphoma: clinical utility of romidepsin

Correspondence: Jasmine Zain NYU Langone Medical Center, 160 East 34th Street, 11th Floor, New York, NY 10016, USA Tel +1 212 731 6544 Fax +1 212 731 5540 Email jasmine.zain@nyumc.org Introduction: Direct therapeutic targets, such as aberrant tumor cell genes and tumor cell markers, have been the focus of cancer treatment for more than 50 years. The resulting damage to normal cells and emergence of drug-resistant tumor cells after exposure to conventional chemotherapy have led researchers to study indirect targets, like the tumor vasculature. A more recent indirect approach involves targeting the epigenetic modifiers, DNA methyltransferase and histone deacetylase. Histone deacetylase inhibitors have been shown to be active cytotoxic agents in T cell lymphoma. The current treatments approved by the US Food and Drug Administration for relapsed cutaneous T cell lymphoma are vorinostat and romidepsin. The diversity and rarity of peripheral T cell lymphomas present a challenge for effective treatment. With their poor overall survival rate, new targeted therapies need to be developed.

EF24 Induces G2/M Arrest and Apoptosis in Cisplatin-resistant Human Ovarian Cancer Cells by Increasing PTEN Expression

We report that EF24, a synthetic compound 3,5-bis(2-flurobenzylidene)piperidin-4-one, greatly inhibits cisplatin-resistant (CR) human ovarian cancer cell proliferation. The inhibitory effect of EF24 on cell proliferation is associated with G(2)/M phase cell cycle arrest and increased G(2)/M checkpoint protein (pp53, p53, and p21) levels. Within 24 h following treatment, EF24 induced apoptosis in CR cells. The apoptosis was partially blocked by the general caspase inhibitor z-VAD. Within 12 h, EF24 induced a membranous FasL expression, consistent with a substantial decrease in the Ser(473) and Thr(308) phosphorylation of Akt, a known negative regulator of FasL transcription. Also, EF24 activated the phosphorylated PTEN and marginally up-regulated total PTEN expression through the inhibition of ubiquitin-mediated PTEN degradation. Suppression of PTEN expression with siRNA significantly reduced the p53 and p21 levels and activated Akt phosphorylation at Ser(473) and Thr(308), resulting in decreased apoptosis and increased cell survival. On the other hand, overexpression of PTEN markedly induced apoptosis. Our results clearly suggested that EF24 induced significant increase in PTEN expression. The up-regulation of PTEN inhibited Akt and MDM2, which enhanced the level of p53, thereby inducing G(2)/M arrest and apoptosis. Therefore, EF24 appears to have a potential therapeutic role in human ovarian cancer through the activation of PTEN.

Metronomic chemotherapy: an antiangiogenic scheduling

Conventional cytotoxic anticancer chemotherapeutic drugs were developed with the intent of treating cancer by direct killing or inhibition of growth of cycling tumour cells. Recently, however, there has been considerable interest in the notion of exploiting such drugs as angiogenesis inhibitors. The rationale is based on the fact that virtually all classes of cancer chemotherapeutic drugs are designed to damage DNA or disrupt microtubules of dividing cells, and endothelial cell division takes place during new blood vessel formation, including tumour angiogenesis. The results of recent experimental studies have suggested that frequent administration of certain cytotoxic agents at low doses, known as "metronomic chemotherapy", increases the putative antiangiogenic activity of certain drugs. Metronomic chemotherapy refers to the chronic administration of comparatively low doses of cytotoxic drugs at close, regular intervals, with no prolonged drug-free interruptions. The advantage of this strategy is lower toxicity and risk of emergence of drug-resistant tumour cells than conventional administration. This review describes the possible antiangiogenesis basis of this therapeutic strategy, the experimental studies published and the recent clinical studies that explore this less toxic schedule.

Regulation of Class II β-Tubulin Expression by Tumor Suppressor p53 Protein in Mouse Melanoma Cells in Response toVincaAlkaloid

The continuous exposure of antimicrotubule drugs to tumors often results in the emergence of drug-resistant tumor cells with altered expression of several beta-tubulin isotypes. We found that Vinca alkaloid enhanced expression of class II beta-tubulin isotype (mTUBB2) in mouse B16F10 melanoma cells via alteration of the tumor suppressor p53 protein. Vincristine treatment stimulated an increase in mTUBB2 mRNA expression and promoted accumulation of this isotype around the nuclei. Transient transfection assays employing a reporter construct, together with site-directed mutagenesis studies, suggested that the p53-binding site found in the first intron was a critical region for mTUBB2 expression. Electrophoretic mobility shift assay and associated antibody supershift experiments showed that vincristine promoted release of p53 protein from the binding site. In addition, exogenous induction of TAp63gamma (p51A), a homologue of p53, canceled the effect of vincristine on mTUBB2 expression. These results suggest that p53 protein may function as a suppressor of mTUBB2 expression and vincristine-mediated inhibition of p53 binding results in enhanced mTUBB2 expression. This phenomenon could be related with the emergence of drug-resistant tumor cells induced by Vinca alkaloid and may participate in determining the fate of these cells.

Fanconi anemia

What is it? Fanconi anemia (FA) is an autosomal recessive human disease characterized by congenital malformations, bone marrow failure and cancer. FA patients often develop leukemia and/or squamous cell carcinomas of the head and neck or gynecologic system. FA cells are hypersensitive to DNA crosslinking agents, such as mitomycin C (MMC) or diepoxybutane (DEB), and the syndrome is believed to result from a defect in DNA repair. The genetics of FA? From somatic cell fusion studies, FA has at least eight complementation groups. Seven FA genes have been cloned, corresponding to subtypes A, C, D1, D2, E, F and G. Interestingly, the FANCD1 gene is identical to the breast cancer susceptibility gene BRCA2. Biallelic disruption of any of these seven FA genes results in the common clinical and cellular phenotype of FA patients. FANCD2 is the only FA gene with known homologues in invertebrates (Drosophila and CaenorhabditisÊelegans). What is the function of the FA genes? Perhaps not surprisingly, the seven cloned FA proteins interact in a common signaling pathway (Figure 1). In a normal human cell, five of the FA proteins – A, C, E, F and G – form a nuclear complex, required for the monoubiquitination of the downstream FANCD2 protein. After cellular exposure to genotoxic agents, monoubiquitinated (activated) FANCD2 is targeted to nuclear foci which also contain BRCA1 and FANCD1/BRCA2. Any related human syndromes? Other human genetic diseases, such as ataxia telangiectasia (AT) and Nijmegen's breakage syndrome (NBS), also display spontaneous chromosome breakage and cancer predisposition. Interestingly, the ATM and NBS1 proteins interact with elements of the FA/BRCA pathway, perhaps accounting for the partial overlap in these clinical syndromes. What does the FA/BRCA pathway do? Recent evidence indicates that biallelic mutations of BRCA1 or BRCA2 in tumor cells results in a defect in DNA repair by homologous recombination. The FA/BRCA pathway appears to regulate homologous recombination repair during S phase or following DNA damage by crosslinking agents, although the precise function of the downstream monoubiquitinated FANCD2 protein in this process remains unknown. Relevance to cancer in the general population? Like many human cancers, FA cells display chromosome instability and cis-platinum sensitivity. Recent studies indicate that acquired (somatic) disruption of the FA/BRCA pathway can account for these features in some sporadic tumors in the general population, such as ovarian and breast cancer. The FANCF gene, for example, is methylated and inactivated in approximately 20% of epithelial ovarian cancers, perhaps accounting for the cis-platinum sensitivity of at least a subset of these tumors. Demethylation of FANCF and reactivation of the FA/BRCA pathway may result in the emergence of drug-resistant tumor cells. Are FA genes also BRCA genes?BRCA2+/− heterozygotes have an increased risk of developing breast, ovarian and other cancers. As BRCA2 is an FA gene, we speculate that heterozygote carriers of mutations in other FA genes – A, C, D2, E, F and G – may also have an increased cancer risk. The cancer risk may depend on the FA subtype or the presence of specific mutant FA alleles.

Cellular mechanisms of cyclophosphamide resistance: model studies in human medulloblastoma cell lines.

Cyclophosphamide is extremely active in the treatment of medulloblastoma, the most common malignant tumor arising in the central nervous system of children’. Phase 2 trials in children with recurrent and newly diagnosed medulloblastoma have confirmed both clinical and radiographic responses to this alkylating agent2-5and a current Children’s Oncology Group international Phase 3 trial is comparing a cyclophosphamide-based regimen to a CCNU-based regimen for children with newly diagnosed high-risk medulloblastoma. Unfortunately, patients with medulloblastoma treated with cyclophosphamide frequently fail therapy, confirming the emergence of drug-resistant tumor cells. Although selection of alternative treatment for these patients who relapse is the only option currently available, definition of the mechanism(s) responsible for cyclophosphamide resistance might provide new therapeutic strategies to reverse or even prevent resistance to this alkylator

Regulation of MDR1 gene expression: emerging concepts.

Drug resistance genes, such as MDR1, involved in drug efflux, and their regulation have been the subject of intense research efforts in the past 10 years. Many factors and cellular signalling pathways play a role in the regulation of MDR1 gene expression. Commonly used chemotherapeutic agents activate in vitro and in vivo general stress response pathways, potential targets of which include MDR1 and other drug resistance genes. The contribution of these agents to the emergence of drug-resistant tumour cells is of concern. Recent evidence points to a role for the epigenetic regulation of MDR1 gene expression. The identification of key components in the DNA methylation/chromatin system of gene regulation may in time lead to more informed and targeted approaches to treating drug-resistant tumours. Copyright 2000 Harcourt Publishers Ltd.

Differential Catalytic Efficiency of Allelic Variants of Human GlutathioneS-Transferase Pi in Catalyzing the Glutathione Conjugation of Thiotepa

Alkylating agents are extensively used in the treatment of cancer. The clinical usefulness of this class of anticancer drugs, however, is often limited by the emergence of drug-resistant tumor cells. Increased glutathione (GSH) conjugation through catalysis by GSHS-transferases (GSTs) is believed to be an important mechanism in tumor cell resistance to alkylating agents. In the present study, we report that the allelic variants of human Pi class GST (hGSTP1-1), which differ in their primary structures at amino acids in positions 104 and/or 113, exhibit significant differences in their activity in the GSH conjugation of alkylating anticancer drug thiotepa. Mass spectrometry revealed that the major product of the reaction between thiotepa and GSH was the monoglutathionyl–thiotepa conjugate. While nonenzymatic formation of monoglutathionyl–thiotepa was negligible, the formation of this conjugate was increased significantly in the presence of hGSTP1-1 protein. The hGSTP1-1-catalyzed GSH conjugation of thiotepa was time and protein dependent and followed Michaelis–Menten kinetics. The catalytic efficiency of hGSTP1-1(I104,A113) variant was approximately 1.9- and 2.6-fold higher compared with hGSTP1-1(V104,A113) and hGSTP1-1(V104,V113) isoforms, respectively. The results of the present study indicate that the hGSTP1-1 polymorphism may be an important factor in GST-mediated tumor cell resistance to thiotepa, and that subjects homozygous for thehGSTP1-1(I104,A113)allele, which is most frequent in human populations, are likely to be at a greater risk for developing GST-mediated resistance to thiotepa than heterozygotes or homozygotes with valine 104 background.

Recent insights into platinum drug resistance in cancer

Cisplatin and its analogs have become important components of chemotherapeutic regimens for the treatment of solid tumors, however, their overall effectiveness is limited by the emergence of drug-resistant tumor cells. Resistance to the platinum drugs is multifactorial consisting of mechanisms that prevent the formation of lethal platinum-DNA adducts and mechanisms that operate downstream of the drug/target interaction to promote cell survival. Continued progress in the study of the drug resistance phenotype as well as the development of new platinum analogs may eventually lead to improved therapies and increased survival rates.