Chemoresistance is one of the major obstacles for cancer therapy. Abnormal expression of long noncoding RNAs (lncRNAs) was broadly implicated in chemoresistance of multiple cancers. This study was ...aimed to investigate the function of urothelial cancer associated 1 (
) in multidrug resistance of retinoblastoma and its potential molecular mechanism. In this study, we observed that
was significantly upregulated in chemoresistant retinoblastoma tissues and multidrug resistant retinoblastoma cell lines and predicted an unfavorable overall survival. Functionally, knockdown of
remarkably inhibited proliferation and sensitized retinoblastoma cells to multiple chemotherapy drugs, including vincristine (VCR), carboplatin (CBP), cisplatin (DDP), VP-16 (etoposide), and 5-fluorouracil (5-Fu). Mechanistic studies demonstrated that
functioned as a miRNA sponge to increase stathmin 1 (
) expression through sponging miR-513a-5p. In addition, silence of miR-513a-5p or
overexpression could partly reverse
knockdown-induced inhibitory effects on proliferation and multidrug resistance of retinoblastoma cells. Overall, this study is the first to demonstrate that
plays a critical role in retinoblastoma chemoresistance, and
may serve as a potential diagnostic biomarker and therapeutic target of retinoblastoma.
Abstract
Long noncoding RNAs (lncRNAs) are known to regulate DNA damage response (DDR) and genome stability in proliferative cells. However, it remains unknown whether lncRNAs are involved in these ...vital biological processes in post-mitotic neurons. Here, we report and characterize a lncRNA, termed Brain Specific DNA-damage Related lncRNA1 (BS-DRL1), in the central nervous system. BS-DRL1 is a brain-specific lncRNA and depletion of BS-DRL1 in neurons leads to impaired DDR upon etoposide treatment in vitro. Mechanistically, BS-DRL1 interacts with HMGB1, a chromatin protein that is important for genome stability, and is essential for the assembly of HMGB1 on chromatin. BS-DRL1 mediated DDR exhibits cell-type specificity in the cortex and cerebellum in gamma-irradiated mice and BS-DRL1 knockout mice show impaired motor function and concomitant purkinje cell degeneration. Our study extends the understanding of lncRNAs in DDR and genome stability and implies a protective role of lncRNA against neurodegeneration.
PRRX1 is a homeodomain transcriptional factor, which has two isoforms, PRXX1A and PRRX1B. The PRRX1 isoforms have been demonstrated to be important in pancreatic cancer, especially in the regulation ...of epithelial-to-mesenchymal transition (EMT) in Pancreatic Ductal Adenocarcinoma (PDAC) and of mesenchymal-to-epithelial transition (MET) in liver metastasis. In order to determine the functional underpinnings of PRRX1 and its isoforms, we have unraveled a new interplay between PRRX1 and the FOXM1 transcriptional factors. Our detailed biochemical analysis reveals the direct physical interaction between PRRX1 and FOXM1 proteins that requires the PRRX1A/B 200-222/217 amino acid (aa) region and the FOXM1 Forkhead domain. Additionally, we demonstrate the cooperation between PRRX1 and FOXM1 in the regulation of FOXM1-dependent transcriptional activity. Moreover, we establish FOXM1 as a critical downstream target of PRRX1 in pancreatic cancer cells. We demonstrate a novel role for PRRX1 in the regulation of genes involved in DNA repair pathways. Indeed, we show that expression of PRRX1 isoforms may limit the induction of DNA damage in pancreatic cancer cells. Finally, we demonstrate that targeting FOXM1 with the small molecule inhibitor FDI6 suppress pancreatic cancer cell proliferation and induces their apoptotic cell death. FDI6 sensitizes pancreatic cancer cells to Etoposide and Gemcitabine induced apoptosis. Our data provide new insights into PRRX1's involvement in regulating DNA damage and provide evidence of a possible PRRX1-FOXM1 axis that is critical for PDAC cells.
An assembly‐induced retention effect for enhanced tumor photoacoustic (PA) imaging and therapeutics is described. A responsive small‐molecule precursor is prepared that simultaneously self‐assembles ...into nanofibers in tumor sites that exhibit an assembly‐induced retention effect, which results in an improved PA imaging signal and enhanced therapeutic efficacy. This successful proof‐of‐concept study paves the way to develop novel supramolecular biomaterials for cancer diagnostics and therapeutics.
Abstract
Etoposide and other topoisomerase II-targeted drugs are important anticancer therapeutics. Unfortunately, the safe usage of these agents is limited by their indiscriminate induction of ...topoisomerase II-mediated DNA cleavage throughout the genome and by a lack of specificity toward cancer cells. Therefore, as a first step toward constraining the distribution of etoposide-induced DNA cleavage sites and developing sequence-specific topoisomerase II-targeted anticancer agents, we covalently coupled the core of etoposide to oligonucleotides centered on a topoisomerase II cleavage site in the PML gene. The initial sequence used for this 'oligonucleotide-linked topoisomerase inhibitor' (OTI) was identified as part of the translocation breakpoint of a patient with acute promyelocytic leukemia (APL). Subsequent OTI sequences were derived from the observed APL breakpoint between PML and RARA. Results indicate that OTIs can be used to direct the sites of etoposide-induced DNA cleavage mediated by topoisomerase IIα and topoisomerase IIβ. OTIs increased levels of enzyme-mediated cleavage by inhibiting DNA ligation, and cleavage complexes induced by OTIs were as stable as those induced by free etoposide. Finally, OTIs directed against the PML-RARA breakpoint displayed cleavage specificity for oligonucleotides with the translocation sequence over those with sequences matching either parental gene. These studies demonstrate the feasibility of using oligonucleotides to direct topoisomerase II-mediated DNA cleavage to specific sites in the genome.
Background
To assess feasibility and safety of outpatient administration of ifosfamide and etoposide (IE) for pediatric Ewing sarcoma (EWS) patients in a resource‐limited setting amid the COVID‐19 ...pandemic.
Materials and Methods
Retrospective study of patients with EWS who received outpatient IE from January 2020 until January 2021 at our institution. Ifosfamide 1800 mg/m2 was given for 5 days with MESNA (2‐mercaptoethane sulfonate sodium) infusion and additional boluses before and after 9 hours of hydration. Patients >10 years of age with the ability to drink orally at home, no pre‐existing renal dysfunction or history of hematuria were included. They were monitored for hemorrhagic cystitis with a urine dipstick before, midway, and at end of infusion. A urine analysis was done 24 hours after the last dose of ifosfamide.
Results
Forty‐seven (100%) cycles were given as outpatient during the study period. Thirty‐five (74%) cycles were given on time, two (4%) cycles were delayed due to mucositis, two (4%) due to delayed count recovery, and eight (18%) due to unavailability of outpatient appointments. The median interval between these cycles was 15 days (range 14–44 days). No episode of hemorrhagic cystitis was reported. Urine analysis was not done at 24 hours for 27 (58%) cycles, so microscopic hematuria may have been missed. This outpatient protocol saved 32% (USD 299) per cycle in cost and 282 days of hospitalization.
Conclusion
Outpatient administration of IE for pediatric patients with EWS is feasible, safe, and cost‐effective during the COVID‐19 pandemic.
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•A method to quantify the decomposition products from etoposide was developed and validated.•Degradation kinetics were studied and degradations products were elucidated using ...LC-HR-MSn and computational methods.•Physico-chemical stability of etoposide in ready-to-use chloride or glucose solutions was determined.•The article is a direct consequence of the need to use alternative pharmaceuticals due to a global shortage of Etopophos®.
The generic Mylan® etoposide (ETP) has been investigated as an alternative for Etopophos®, in part due to a global shortage of the latter. The generic alternative is different both in its formulation and in its very limited stability (6 h at 25 °C against 4 days for Etopophos®) once reconstituted in ready-to-use chloride or glucose solutions. Its intrinsic stability has been thoroughly studied under various conditions. Two degradation products resulting from hydrolysis were characterized by LC-HR-MSn and supported by density functional theory calculations of the frontier molecular orbitals energies, molecular electrostatic potential mapping, and Mulliken charge analysis. Chemical degradation increases with temperature and can be fitted to a zero order kinetic model with a half-life of 119 days and a kinetic constant of 0.0028 mM day−1. Precipitation was only observed in solutions at 5 °C and −20 °C indicating that at these temperatures the reconstituted solutions are thermodynamically metastable. In conclusion, ETP at concentrations of 0.68 and 1 mM prepared and stored at 25 °C under good manufacturing practices remained unchanged over a period of 21 days irrespective of the nature of the solvents or the type of container.
Etoposide phosphate (EP), a water-soluble anticancer prodrug, is widely used for treatment of many cancers. After administration it is rapidly converted to etoposide, its parent compound, which ...exhibits anticancer activity. Difficulty in parenteral administration necessitates the development of a suitable nanoparticle delivery system for EP. Here we have used indium both as a carrier to deliver etoposide phosphate to tumor cells and as a SPECT imaging agent through incorporation of (111)In. Etoposide phosphate was successfully encapsulated together with indium in nanoparticles, and exhibited dose dependent cytotoxicity and induction of apoptosis in cultured H460 cancer cells via G2/M cell cycle arrest. In a mouse xenograft lung cancer model, etoposide phosphate/indium nanoparticles induce tumor cell apoptosis, leading to significant enhancement of tumor growth inhibition compared to the free drug.
Tumor hypoxia negatively regulates cell growth and causes a more malignant phenotype by increasing the expression of genes encoding angiogenic, metabolic and metastatic factors. Of clinical ...importance, insufficient tumor oxygenation affects the efficiency of chemotherapy and radiotherapy by poorly understood mechanisms. The hypoxia-inducible factor (HIF)-1 is a master transcriptional activator of oxygen-regulated genes and HIF-1 is constitutively upregulated in several tumor types. HIF-1 might thus be implicated in tumor therapy resistance. We found that transformed mouse embryonic fibroblasts deficient for HIF-1alpha are more susceptible to the treatment with carboplatin, etoposide and ionizing radiation than wild-type cells. Increased cell death in HIF-1alpha-deficient cells was because of apoptosis and did not involve p53 induction. Tumor chemotherapy of experimental fibrosarcoma in immunocompromised mice with carboplatin and etoposide confirmed the enhanced susceptibility of HIF-1alpha-deficient cells. Agents that did not cause DNA double-strand breaks, such as DNA-synthesis inhibitors or a DNA single-strand break-causing agent equally impaired cell growth, independent of the HIF-1alpha genotype. Functional repair of a fragmented reporter gene was decreased in HIF-1alpha-deficient cells. Thus, hypoxia-independent basal HIF-1alpha expression in tumor cells, as known from untransformed embryonic stem cells, is sufficient to induce target gene expression, probably including DNA double-strand break repair enzymes.
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