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Multi-target therapies have been considered one of the viable options to overcome the challenges to eradicate intrinsic and acquired drug-resistant cancer cells. While to increase the efficacy of therapeutics, the use of a single drug against multiple structurally similar sites, which noncommittedly modulate several vital cellular pathways proposed as a potential alternative to a 'single drug single target'. Besides, it reduces the usage of a number of drugs and their side effects. Topoisomerase II enzyme plays a very significant role in DNA replication and thus served as an important target for numerous anti-cancer agents. However, in spite of promising clinical results, in several cases, it was found that cancer cells have developed resistance against the anti-cancer agents targeting this enzyme. Therefore, multi-target therapies have been proposed as an alternative to overcome different drug resistance mechanisms while topoisomerases II are a primary target site. In this review, we have tried to discuss the characteristics of the binding cavity available for interactions of drugs, and potent inhibitors concurrently modulate the functions of topoisomerases II as well as other structurally related target sites. Additionally, the mechanism of drug resistance by considering molecular and cellular insights by including various types of cancers.

Damage-associated molecular patterns (DAMPs) contribute to antitumor immunity during cancer chemotherapy. We previously demonstrated that topotecan (TPT), a topoisomerase I inhibitor, induces DAMP secretion from cancer cells, which activates STING-mediated antitumor immune responses. However, how TPT induces DAMP secretion in cancer cells is yet to be elucidated. Here, we identified RPL15, a 60S ribosomal protein, as a novel TPT target and showed that TPT inhibited preribosomal subunit formation via its binding to RPL15, resulting in the induction of DAMP-mediated antitumor immune activation independent of TOP1. TPT inhibits RPL15–RPL4 interactions and decreases RPL4 stability, which is recovered by CDK12 activity. RPL15 knockdown induced DAMP secretion and increased the CTL population but decreased the regulatory T cell population in a B16-F10 murine melanoma model, which sensitized B16-F10 tumors against PD-1 blockade. Our study identified a novel TPT target protein and showed that ribosomal stress is a trigger of DAMP secretion, which contributes to antitumor immunotherapy.

Effects of UGT1A1*6 and UGT1A1*28 genetic polymorphisms on irinotecan-induced severe toxicities in Asian cancer patients are inconclusive. Also, ABCC2 c.3972CT may affect toxicity of irinotecan. The aim was to assess the aggregated risk of neutropenia or diarrhea in Asian cancer patients taking irinotecan and inherited UGT1A1*6, UGT1A1*28, or ABCC2 c.3972CT genetic variants. A PubMed literature search for eligible studies was conducted. Odds ratios (ORs) were measured using RevMan software where p values0.05 were statistically significant. Patients that inherited both UGT1A1*6 and UGT1A1*28 genetic variants (heterozygous: UGT1A1*1/*6 + *1/*28 and homozygous: UGT1A1*6/*6 + *28/*28) were significantly associated with increased risk of neutropenia and diarrhea compared to patients with UGT1A1*1/*1 (neutropenia: OR 2.89; 95% CI 1.97-4.23; p 0.00001; diarrhea: OR 2.26; 95% CI 1.71-2.99; p 0.00001). Patients carrying homozygous variants had much stronger effects in developing toxicities (neutropenia: OR 6.23; 95% CI 3.11-12.47; p 0.00001; diarrhea: OR 3.21; 95% CI 2.13-4.85; p 0.00001) than those with heterozygous variants. However, patients carrying the ABCC2 c.3972CT genetic variant were not significantly associated with neutropenia (OR 1.67; 95% CI 0.98-2.84; p = 0.06) and were significantly associated with a reduction in irinotecan-induced diarrhea (OR 0.31; 95% CI 0.11-0.81; p = 0.02). Asian cancer patients should undergo screening for both UGT1A1*6 and UGT1A1*28 genetic variants to reduce substantially irinotecan-induced severe toxicities.

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B7-H3 is overexpressed in various solid tumors and has been considered as an attractive target for cancer therapy. Here, we report the development of DS-7300a, a novel B7-H3–targeting antibody–drug conjugate with a potent DNA topoisomerase I inhibitor, and its in vitro profile, pharmacokinetic profiles, safety profiles, and in vivo antitumor activities in nonclinical species. The target specificity and species cross-reactivity of DS-7300a were assessed. Its pharmacologic activities were evaluated in several human cancer cell lines in vitro and xenograft mouse models, including patient-derived xenograft (PDX) mouse models in vivo. Pharmacokinetics was investigated in cynomolgus monkeys. Safety profiles in rats and cynomolgus monkeys were also assessed. DS-7300a specifically bound to B7-H3 and inhibited the growth of B7-H3–expressing cancer cells, but not that of B7-H3–negative cancer cells, in vitro. Additionally, treatment with DS-7300a and DXd induced phosphorylated checkpoint kinase 1, a DNA damage marker, and cleaved PARP, an apoptosis marker, in cancer cells. Moreover, DS-7300a demonstrated potent in vivo antitumor activities in high–B7-H3 tumor xenograft models, including various tumor types of high–B7-H3 PDX models. Furthermore, DS-7300a was stable in circulation with acceptable pharmacokinetic profiles in monkeys, and well tolerated in rats and monkeys. DS-7300a exerted potent antitumor activities against B7-H3–expressing tumors in in vitro and in vivo models, including PDX mouse models, and showed acceptable pharmacokinetic and safety profiles in nonclinical species. Therefore, DS-7300a may be effective in treating patients with B7-H3–expressing solid tumors in a clinical setting.

A diselenide/disulfide unit was introduced into camptothecin (CPT), and two selenoprodrugs (e.g., CPT-Se3 and CPT-Se4) were identified to show improved potency in killing cancer cells and inhibiting tumor growth in vivo. Interestingly, the intrinsic fluorescence of CPT was severely quenched by the diselenide bond. Both the selenoprodrugs were activated by glutathione with a nearly complete recovery of CPT's fluorescence. The activation of prodrugs was accompanied by the production of selenol intermediates, which catalyzed the constant conversion of glutathione and oxygen to oxidized glutathione and superoxides. The diselenide unit is widely employed in constructing thiol-responsive materials. However, the selenol intermediates were largely ignored in the activation process prior to this study. Our work verified that integration of the diselenide unit may further enhance the parent drug's efficacy. Also, the discovery of the fluorescence quenching property of the diselenide/disulfide bond further shed light on constructing novel theranostic agents.

Objective To evaluate the safety and effects of irinotecan, an inhibitor of topoisomerase I, on refractory lupus nephritis. Method A patient with refractory lupus nephritis under medication with mycophenolic acid, prednisolone, and hydroxychloroquine was treated with add-on low-dose irinotecan. Irinotecan was applied every fourth week at a dose of 50 mg/m2 for four cycles followed by 100 mg/m2 for another eight cycles. Renal function and anti-double-stranded DNA antibodies as well as blood count for evaluation of side effects were assessed during the treatment with irinotecan. Results Before starting the treatment with irinotecan, a urine protein/creatinine ratio of 1298 mg/g was determined. This declined to 613 mg/g after four cycles with 50 mg/m2 irinotecan and was further reduced to 198 mg/g when using the higher dose of irinotecan. Kidney function remained stable, with creatinine levels of 1.66 mg/dL at the beginning and 1.76 mg/dL at the end of treatment with irinotecan. Importantly, no side effects, such as diarrhoea or neutropenia, were observed during the entire course of treatment. Conclusion Administration of low-dose irinotecan as add-on medication for the treatment of refractory lupus nephritis was shown to be safe. Clinical trials are needed to determine whether irinotecan can improve kidney function and the outcome of patients with refractory lupus nephritis.

Understanding the rationale of combining immunotherapy and other anticancer treatment modalities is of great interest because of interpatient variability in single-agent immunotherapy. Here, we demonstrated that topoisomerase I inhibitors, a class of chemotherapeutic drugs, can alter the tumor immune landscape, corroborating their antitumor effects combined with immunotherapy. We observed that topotecan-conditioned TC-1 tumors were occupied by a vast number of monocytic cells that highly express CD11c, CD64, and costimulatory molecules responsible for the favorable changes in the tumor microenvironment. Ly6C+MHC-II+CD11chiCD64hi cells, referred to as topotecan-induced monocyte-derived dendritic cells (moDCs), proliferate and activate antigen-specific CD8+ T cells to levels equivalent to those of conventional DCs. Phenotypic changes in Ly6C+ cells towards moDCs were similarly induced by exposure to topotecan in vitro, which was more profoundly facilitated in the presence of tumor cells. Notably, anti-M-CSFR reversed the acquisition of DC-like properties of topotecan-induced moDCs, leading to the abolition of the antitumor effect of topotecan combined with a cancer vaccine. In short, topoisomerase I inhibitors generate monocyte-derived antigen-presenting cells in tumors, which could be mediated by M-CSF-M-CSFR signaling.

Visceral leishmaniasis (VL) is a fatal infectious disease caused by viscerotropic parasitic species of Leishmania. Current treatment options are often ineffective and toxic, and more importantly, there are no clinically validated drug targets available to develop next generation therapeutics against VL. Topoisomerase IB (TopIB) is an essential enzyme for Leishmania survival. The enzyme is organized as a bi-subunit that is distinct from the monomeric topoisomerase I of human. Based on this unique feature, we synthesized peptides composed of partial amino acid sequences of small subunit of Leishmania donovani (Ld) TopIB to confirm a decrease in catalytic activity by interfering the interaction between the two subunits. One of the synthetic peptides, covering essential amino acids for catalytic activity of LdTopIB, interrupted the enzymatic activity. Next, we examined 151 compounds selected from virtual screening in a functional assay and identified three LRL-TP compounds with a significant decrease in LdTopIB activity (IC50 of LRL-TP-85: 1.3 μM; LRL-TP-94: 2.9 μM; and LRL-TP-101: 35.3 μM) and no effects on Homo sapiens (Hs) TopIB activity. Based on molecular docking, the protonated tertiary amine of inhibitors formed key interactions with S415 of the large subunit. The EC50 values of LRL-TP-85, LRL-TP-94, and LRL-TP-101 were respectively 4.9, 1.4, and 27.8 μM in extracellular promastigote assay and 34.0, 53.7, and 11.4 μM in intracellular amastigote assay. Overall, we validated the protein-protein interaction site of LdTopIB as a potential drug target and identified small molecule inhibitors with anti-leishmanial activity.

The understanding of the mechanism of Topo I inhibition by organic ligands is a crucial source of information that has led to the design of more effective and safe pharmaceuticals in oncological chemotherapy. The vast number of inhibitors that have been studied in this respect over the last decades have enabled the creation of a concept of an ‘interfacial inhibitor’, thereby describing the machinery of Topo I inhibition. The central module of action of this machinery is the interface of a Topo I/DNA/inhibitor ternary complex. Most of the ‘interfacial inhibitors’ are primarily kinetic inhibitors that form molecular complexes with an “on–off” rate timing; therefore, all of the contacts between the inhibitor and both the enzyme and the DNA are essential to keep the complex stable and reduce the “off rate”. To test this hypothesis, we designed the compound using a C-9-(N-(2′-hydroxyethyl)amino)methyl substituent in an SN38 core, with a view that a flexible substituent may bind inside the nick of a model of the DNA and stabilize the complex, leading to a reduction in the “off rate” of a ligand in a potential ternary complex in vivo. Using docking analysis and molecular dynamics, free energy calculations on the level of the MM-PBSA and MM-GBSA model, here we presented the in silico-calculated structure of a ternary complex involving the studied compound 1. This confirmed our suggestion that compound 1 is situated in a groove of the nicked DNA model in a few conformations. The number of hydrogen bonds between the components of a ternary complex was established, which strengthens the complex and supports our view. The docking analysis and free energy calculations for the receptor structures which were obtained in the MD simulations of the ternary complex 1/DNA/Topo I show that the binding constant is stronger than it was for similar complexes with TPT, CPT, and SN38, which are commonly considered as strong Topo I inhibitors. The binary complex structure 1/DNA was calculated and compared with the experimental results of a complex that was in a solution. The analysis of the cross-peaks in NOESY spectra allowed us to assign the dipolar interactions between the given protons in the calculated structures. A DOSY experiment in the solution confirmed the strong binding of a ligand in a binary complex, having a Ka of 746 mM−1, which was compared with a Ka of 3.78 mM−1 for TPT. The MALDI-ToF MS showed the presence of the biohybrid, thus evidencing the occurrence of DNA alkylation by compound 1. Because of it having a strong molecular complex, alkylation is the most efficient way to reduce the “on–off” timing as it acts as a tool that causes the cog to brake in a working gear, and this is this activity we want to highlight in our contribution. Finally, the Topo I inhibition test showed a lower IC50 of the studied compound than it did for CPT and SN38.

DNA topoisomerase I was found to be highly abundant in fast-proliferating tumor cells and is a potential target for anticancer therapy. A series of G-quadruplex-containing oligodeoxynucleotides (ODNs) were designed and used as inhibitors of DNA topoisomerase I. It was demonstrated that ODNs with G-quadruplexes can efficiently inhibit the supercoiled DNA relaxation reaction catalyzed by DNA topoisomerase I. Compared with the other conformations, the parallel propeller-type G-quadruplex was the most efficient DNA topoisomerase I inhibitor. Further studies revealed that integrating G-quadruplexes with duplexes to form quadruplex-duplex hybrids could significantly improve the inhibition efficiency. In addition, a circular ODN that consists of a G-quadruplex motif and DNA topoisomerase I binding site was synthesized and used as a DNA topoisomerase I inhibitor. The results showed that the particularly designed circular ODN displayed high inhibitory efficiency on the activity of DNA topoisomerase I with an IC

Background A cisplatin plus irinotecan (CPT‐11) regimen is used for patients with extensive disease small cell lung cancer (ED‐SCLC). Amrubicin (AMR) is primarily used for relapsed SCLC. The HOT1401/NJLCG1401 trial, an open‐label randomized phase II trial, was designed to assess the benefit of maintenance therapy in patients with ED‐SCLC who responded to induction therapy. Methods Patients with histologically‐ or cytologically‐confirmed ED‐SCLC were included and were treated with an induction therapy of four cycles of cisplatin (60 mg/m2 on day 1) plus CPT‐11 (60 mg/m2 on days 1, 8, and 15) every four weeks. After induction therapy, patients who had nonprogressive disease were randomized to receive either maintenance CPT‐11 (60 mg/m2 on days 1 and 8) every three weeks, or AMR (35 mg/m2 on days 1–3) every three weeks. Results A total of 34 patients were enrolled; 20 patients had progressive disease or received incomplete induction chemotherapy. Finally, 14 patients were randomly assigned to receive CPT‐11 (n = 7) or AMR (n = 7). This study was terminated prematurely because of low patient accrual. The overall objective response rate was 73%, the median PFS was 5.7 months (95% confidence interval [CI]: 3.6–11.8), and the median overall survival was 20.1 months (95% CI: 13.7–not reached). No statistically significant difference in progression‐free survival (PFS) were noted between patients treated with CPT‐11 and those treated with AMR. There were no treatment‐related deaths in this study. Conclusions Maintenance therapy with CPT‐11 or AMR after induction therapy might be effective in some patients., There were some patients who achieved long disease control. Maintenance therapy with CPT‐11 or AMR after induction therapy could have potential for treating ED‐SCLC.

Irinotecan is a kind of alkaloid with antitumour activity, but its low solubility and high toxicity limit its application. Epigallocatechin‐3‐gallate (EGCG) is one of the main bioactive components in tea. The epidemiological investigation and animal and cell experiments show that EGCG has a preventive and therapeutic effect on many kinds of tumours. Here, colorectal cancer cells RKO and HCT116 were employed, and the CCK8 proliferation test was used to screen the appropriate concentration of EGCG and irinotecan, and the effects of single and/or combined drugs on migration, invasion, DNA damage, cell cycle and autophagy of tumour cells were investigated. The results showed that EGCG combined with irinotecan (0.5 μmol L−) not only had a stronger inhibitory effect on tumour cells than EGCG or irinotecan alone but also prevented tumour cell migration and invasion. EGCG alone did not cause DNA damage in colorectal cancer cells, but its combination with irinotecan could induce S or G2 phase arrest by inhibiting topoisomerase I to cause more extensive DNA damage. EGCG also induced apoptosis by promoting autophagy with irinotecan synergistically. These results indicated that EGCG in combination with irinotecan could be a promising strategy for colorectal cancer.

Exatecan and deruxtecan are antineoplastic camptothecin derivatives in development as tumor-targeted-delivery warheads in various formulations including peptides, liposomes, polyethylene glycol nanoparticles, and antibody–drug conjugates. Here, we report the molecular pharmacology of exatecan compared with the clinically approved topoisomerase I (TOP1) inhibitors and preclinical models for validating biomarkers and the combination of exatecan with ataxia telangiectasia and Rad3-related kinase (ATR) inhibitors. Modeling exatecan binding at the interface of a TOP1 cleavage complex suggests two novel molecular interactions with the flanking DNA base and the TOP1 residue N352, in addition to the three known interactions of camptothecins with the TOP1 residues R364, D533, and N722. Accordingly, exatecan showed much stronger TOP1 trapping, higher DNA damage, and apoptotic cell death than the classical TOP1 inhibitors used clinically. We demonstrate the value of SLFN11 expression and homologous recombination (HR) deficiency (HRD) as predictive biomarkers of response to exatecan. We also show that exatecan kills cancer cells synergistically with the clinical ATR inhibitor ceralasertib (AZD6738). To establish the translational potential of this combination, we tested CBX-12, a clinically developed pH-sensitive peptide–exatecan conjugate that selectively targets cancer cells and is currently in clinical trials. The combination of CBX-12 with ceralasertib significantly suppressed tumor growth in mouse xenografts. Collectively, our results demonstrate the potency of exatecan as a TOP1 inhibitor and its clinical potential in combination with ATR inhibitors, using SLFN11 and HRD as predictive biomarkers.

Targeting myeloid cells, especially microglia, for the treatment of neuroinflammatory diseases such as multiple sclerosis (MS), is underappreciated. Our in silico drug screening reveals topoisomerase 1 (TOP1) inhibitors as promising drug candidates for microglial modulation. We show that TOP1 is highly expressed in neuroinflammatory conditions, and TOP1 inhibition using camptothecin (CPT) and its FDA-approved analog topotecan (TPT) reduces inflammatory responses in microglia/macrophages and ameliorates neuroinflammation in vivo. Transcriptomic analyses of sorted microglia from LPS-challenged mice reveal an altered transcriptional phenotype following TPT treatment. To target myeloid cells, we design a nanosystem using β-glucan-coated DNA origami (MyloGami) loaded with TPT (TopoGami). MyloGami shows enhanced specificity to myeloid cells while preventing the degradation of the DNA origami scaffold. Myeloid-specific TOP1 inhibition using TopoGami significantly suppresses the inflammatory response in microglia and mitigates MS-like disease progression. Our findings suggest that TOP1 inhibition in myeloid cells represents a therapeutic strategy for neuroinflammatory diseases and that the myeloid-specific nanosystems we designed may also benefit the treatment of other diseases with dysfunctional myeloid cells.

Topoisomerase 1-DNA cleavage complexes (Top1ccs) form at DNA sites of Top1 activity and are increased by a highly specific anticancer drug (camptothecin, CPT) in living cells. Various methods are available to detect Top1ccs in cultured cells, including protocols based on the use of specific antibodies. Here, we describe a protocol to isolate Top1ccs at high purity, which does not depend on antibodies.

Colorectal cancer is one of the most prevalent cancers in the world. Chemoresistance has always been a problem encountered in its treatment. It is known that SUMOylation may regulate protein stability and decomposition, and even affect the protein translocation and posttranslational modification in cells. Sentrin-specific protease 1 (SENP1) is involved in the maturation of SUMO protein, and on the other hand, plays a role in deSUMOylation, which dissociates the target protein from SUMO and prevents further degradation of the target protein. In this study, we established an Irinotecan (CPT-11) resistant human colon cancer LoVo strain (LoVoR-CPT-11 ) to investigate the role of SENP1 in the development of drug resistance in colorectal cancer. The abundant accumulation of SENP1 and HIF-1α proteins and the increase of SUMO pathway enzymes were observed in LoVoR-CPT-11 cells while the protein markers of proliferation, angiogenesis, and glycolysis were upregulated. Knockdown of SENP1 reduced the migration ability and trigged re-sensitivity of LoVoR-CPT-11 cells to CPT-11 treatment. The analysis of SENP1 and HIF-1α gene expressions from TCGA/GTEx datasets using the GEPIA web server showed a positive correlation between SENP1 and HIF-1α in colorectal cancer patients and the high expression of these two genes might predict a poor outcome clinically. In conclusion, SENP1 might play an important role in CPT-11 resistance in colorectal cancer. Targeting SENP1 to reduce the resistant property could be considered in prospective clinical studies.

Topoisomerases are important targets for therapeutic improvement in the treatment of some diseases, including cancer. Inhibitors and poisons of topoisomerase I can limit the activity of this enzyme in its enzymatic cycle. This fact implies an anticancer effect of these drugs, since most cancer cells are characterized by both a higher activity of topoisomerase I and a higher replication rate compared to non-cancerous cells. Clinically approved inhibitors include camptothecin (CPT) and its derivatives. However, their limitations have encouraged different research groups to prepare new compounds, proof of which are the numerous research works and patents, some of them in the last five years.This review covers patent literature on topoisomerase I inhibitors and their application published between 2016-present.The highest contribution toward patent development has been obtained from academics or small biotechnology companies. The most important fields of innovation include the preparation of prodrugs or inhibitors combined with other agents, as biocompatible polymers or antibodies. A promising development of topoisomerase I inhibitors is expected in the next years, directed to the treatment of diverse diseases, specifically toward different types of cancer and infectious diseases, among others.

International audience; PurposeThe aim of the present study was to characterize the pharmacokinetics of irinotecan and its four main metabolites (SN-38, SN-38G, APC and NPC) in metastatic colorectal cancer patients treated with FOLFIRI and FOLFIRINOX regimens and to quantify and explain the inter-individual pharmacokinetic variability in this context.MethodsA multicenter study including 109 metastatic colorectal cancer patients treated with FOLFIRI or FOLFIRINOX regimen, associated or not with a monoclonal antibody, was conducted. Concentrations of irinotecan and its four main metabolites were measured in 506 blood samples during the first cycle of treatment. Collected data were analyzed using the population approach. First, fixed and random effects models were selected using statistical and graphical methods; second, the impact of covariates on pharmacokinetic parameters was evaluated to explain the inter-individual variability in pharmacokinetic parameters.ResultsA seven-compartment model best described the pharmacokinetics of irinotecan and its four main metabolites. First-order rates were assigned to distribution, elimination, and metabolism processes, except for the transformation of irinotecan to NPC which was nonlinear. Addition of a direct conversion of NPC into SN-38 significantly improved the model. Co-administration of oxaliplatin significantly modified the distribution of SN-38.ConclusionTo our knowledge, the present model is the first to allow a simultaneous description of irinotecan pharmacokinetics and of its four main metabolites. Moreover, a direct conversion of NPC into SN-38 had never been described before in a population pharmacokinetic model of irinotecan. The model will be useful to develop pharmacokinetic-pharmacodynamic models relating SN-38 concentrations to efficacy and digestive toxicities.

Benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-ones (BBPIs) are potent anticancer compounds having unique BBPIs ring system designed on the basis of the marine natural product lamellarin D. In this study, we describe an alternative synthesis of a 2-demethoxy series of BBPIs, employing van Leusen pyrrole synthesis and an intramolecular Heck reaction as the key reactions. Cytotoxicity of the derivatives against several cancer and normal cell lines is reported.

10-HCPT is a topoisomerase I inhibitor effective in the treatment of liver cancer but its use is hampered by its resistance. The expression of hypoxia-inducible factor-1α (HIF-1α) is reportedly upregulated in liver cancer tissues, which is directly linked to the resistance of 10-HCPT. While BBR can significantly decrease the level of HIF-1α according to the literature report. Thus, the aim of this study was to prepare a novel intravenous 10-HCPT-BBR-loaded lipid microsphere (LM) and evaluate their synergistic effect on liver cancer treatment. The optimal preparation mainly included 10.0% oil phase (medium-chain triglyceride:long-chain triglyceride = 1:1), emulsifier (egg lecithin E80 and pluronic F68), antioxidant (0.02% NaHSO3), and pH regulator (0.1 mol/L Hcl). Then, the behaviors of BBR-10-HCPT loaded LM in vitro and in vivo were systematically investigated. In vitro, it showed an obvious sustained-release effect in different release mediums, good physicochemical stability at accelerated and long-term storage conditions, and great anti-proliferative capability toward human liver cancer Hep-3B cells. In vivo, the prepared LM exhibited a longer half-life and higher AUC compared to BBR injection and 10-HCPT injection. More importantly, it was found that The LM was distributed more in the liver, spleen, and tumors, but less in the lungs and heart, especially in the lung. And then, it showed significant inhibition of tumor growth against nude mouse with Hep-3B tumor, and the tumor inhibition rate reached 91.55%. Thus, the data obtained in our study suggested that BBR combined with 10-HCPT can raise curative effect and reduce the toxicity of 10-HCPT.

E/L Repli-seq is a powerful tool for detecting cell type-specific replication landscapes in mammalian cells, but its potential to monitor DNA replication under replication stress awaits better understanding. Here, we used E/L Repli-seq to examine the temporal order of DNA replication in human retinal pigment epithelium cells treated with the topoisomerase I inhibitor camptothecin. We found that the replication profiles by E/L Repli-seq exhibit characteristic patterns after replication-stress induction, including the loss of specific initiation zones within individual early replication timing domains. We also observed global disappearance of the replication timing domain structures in the profiles, which can be explained by checkpoint-dependent suppression of replication initiation. Thus, our results demonstrate the effectiveness of E/L Repli-seq at identifying cells with replication-stress-induced altered DNA replication programs.

Background Topotecan is an anti-cancer chemotherapy drug with common side effects, including hepatotoxicity. In this study, we aim to investigate the mechanisms of topotecan-induced hepatocellular injury beyond conventional DNA damage. Materials and methods Methyl Thiazolyl Tetrazolium (MTT) assay was used to detect the inhibitory effect of topotecan on cell proliferation. Western blot was used to detect protein expression. Flow cytometry assay was performed to determine apoptosis rate under topotecan treatment. ASCT2 overexpression was addressed using adenovirus vector. qRT-PCR and western blot assay were used to detect the expression of ASCT2. Glutamine uptake, intracellular glutathione (GSH) and reactive oxygen species (ROS) level were detected by glutamine detection kit, GSH detection kit and ROS detection kit respectively. Results MTT results showed that topotecan had an inhibitory effect on cell proliferation and induced apoptosis in both L02 and HepG2 cell lines. Topotecan inhibited the expression of glutamine transporter ASCT2 and the uptake of glutamine in both L02 and HepG2 cell lines. The uptake of glutamine and the GSH level was increased in both L02 and HepG2 cell lines after ASCT2 overexpression. The ROS level was inhibited by ASCT2 overexpression upon topotecan treatment in both L02 and HepG2 cell lines. Topotecan-induced hepatocellular apoptosis and proliferation inhibition were attenuated by ASCT2 overexpression in both L02 and HepG2 cell lines. Conclusion Topotecan-induced hepatocytes death is dependent on ASCT2 down-regulation, which causes oxidative stress via inhibiting GSH production.

Colorectal cancers (CRCs) is the most commonly diagnosed and deadly cancer types in the world. Despite advances in chemotherapy for CRCs, drug resistance remains a major challenge to high incurable and eventually deadly rates for patients. CPT-11 is one of the current chemotherapy agents for CRC patients and the CPT-11 resistance development of CRCs is also inevitable. Recently, accumulating data has suggested that DNA repair system might be an inducer of chemotherapy resistance in cancer cells. Thus, this study was aimed to examine whether MutS homolog (MSH) 2, one member of DNA repair system, plays a role to affect the cytotoxicity of CPT-11 to CRCs. Human DLD-1 CRC cells were used in this study. It was shown that MSH2 gene and protein expression could be upregulated in DLD-1 cells under CPT-11 treatment and this upregulation subsequently attenuates the sensitivity of DLD-1 cells to CPT-11. Moreover, ERK1/2 and Akt signaling and AP-1 transcription factor have been found to modulate these effects. These results elucidate the drug resistance role of MSH2 upregulation in the CPT-11-treated DLD-1 CRC cells. Our findings may provide a useful thought for new adjuvant drug development by controlling the DNA repair system.

Colorectal cancer is one of the most common cancers in the United States and treatment options are limited for patients who develop liver metastases. Several chemotherapeutic regimens have been used for transvascular liver-directed therapy in the treatment of colorectal liver metastases without clear evidence of superiority of one therapy over another. We describe the development of a novel nanoemulsion through combining irinotecan (IRI), a first line systemic agent used for the treatment of colon cancer, with lipiodol, an oily contrast medium derived from poppy seed oil, and evaluated its pharmacokinetic and biodistribution profile as a function of portal venous chemoembolization (PVCE) versus transarterial chemoembolization (TACE) delivery. The Tessari technique was used to create a stable emulsion (20 mg IRI mixed with 2 mL lipiodol) with resultant particle size ranging from 28.9 nm to 56.4 nm. Pharmacokinetic profile established through venous sampling in Buffalo rats demonstrate that the area under the curve (AUC0−∞) of IRI was significantly less after PVCE with IRI-lipiodol as compared to IRI alone (131 vs. 316 µg*min/mL, p-value = .023), suggesting significantly higher amounts of IRI retention in the liver with the IRI-lipiodol nanoemulsion via first-pass extraction. Subseqent biodistribution studies in tumor-bearing WAG/Rjj rats revealed more IRI present in the tumor following TACE versus PVCE (29.19 ± 12.33 µg/g versus 3.42 ± 1.62; p-value = .0033) or IV (29.19 ± 12.33 µg/g versus 1.05 ± 0.47; p-value = .0035). The IRI-lipiodol nanoemulsion demonstrated an acceptable hepatotoxicity profile in all routes of administration. In conclusion, the IRI-lipiodol nanoemulsion via TACE showed promise and warrants further investigation as an option for the treatment of metastatic colorectal cancer.

Friend leukemia virus integration 1 (Fli-1) is an ETS transcription factor and a critical regulator of inflammatory mediators, including MCP-1, CCL5, IL-6, G-CSF, CXCL2, and caspase-1. GM-CSF is a regulator of granulocyte and macrophage lineage differentiation and a key player in the pathogenesis of inflammatory/autoimmune diseases. In this study, we demonstrated that Fli-1 regulates the expression of GM-CSF in both T cells and endothelial cells. The expression of GM-CSF was significantly reduced in T cells and endothelial cells when Fli-1 was reduced. We found that Fli-1 binds directly to the GM-CSF promoter using chromatin immunoprecipitation assay. Transient transfection assays indicated that Fli-1 drives transcription from the GM-CSF promoter in a dose-dependent manner, and mutation of the Fli-1 DNA binding domain resulted in a significant loss of transcriptional activation. Mutation of a known phosphorylation site within the Fli-1 protein led to a significant increase in GM-CSF promoter activation. Thus, direct binding to the promoter and phosphorylation are two important mechanisms behind Fli-1–driven activation of the GM-CSF promoter. In addition, Fli-1 regulates GM-CSF expression in an additive manner with another transcription factor Sp1. Finally, we demonstrated that a low dose of a chemotherapeutic drug, camptothecin, inhibited expression of Fli-1 and reduced GM-CSF production in human T cells. These results demonstrate novel mechanisms for regulating the expression of GM-CSF and suggest that Fli-1 is a critical druggable regulator of inflammation and immunity.