TOP2A Research Articles

Evaluation of Immunohistochemical Expression of Topoisomerase II Alpha Protein in Patients with Breast Cancer and Its Correlation with Different Prognostic Factors

Background: There are indications to support the knowledge about the prognosis of breast cancer. One of these markers is regarded as a prognostic factor and related to the proliferation rate. Topoisomerase IIα (TOP2A), encoded by the TOP2A gene, is a molecular target for anthracycline therapy. Aims: The aim of this article is to establish any association of the status of topoisomerase IIa immunohistochemistry with different prognostic clinicopathological and molecular parameters in breast cancer. Settings and Design: A cross-sectional retrospective study was carried out in the Department of Pathology and Forensic Medicine, Faculty of Medicine, Babylon University, during the period from January 2020 through December 2020. Materials and Methods: Fifty cases with invasive breast carcinoma have been obtained from surgical modified radical mastectomy specimens from the Laboratory of Histopathology in Al-Kafeel Specialized Hospital, Karbala for the last 3 years (2017–2019). Different clinicopathological variables were estimated. The expression of TOP2A was stained by using the PathnSitu PolyExcel Detection System of Immunostaining. Statistical Analysis Used: Immunostaining with TOP2A expression used a cut-off value of 10%. The results were considered statistically significant if the P-value was ≤ 0.05. Results: Fifty cases of TOP2A overexpression were classified as follows: 28 cases (56%) had 3+ expression, 4 cases (8%) with 2+ expression, and 4 cases (8%) with 1+ expression, whereas 14 cases had no expression of TOP2A (28%). TOP2A overexpression was shown to be associated with a higher grade (P = 0.023) and molecular subtypes (P = 0.057), but not with other clinicopathological parameters (age of patients, type of histology, number of lymph nodes involved, tumor size). Conclusion: According to these results, TOP2A plays a major role in the aggressive nature of tumors. This may support the suggestion to be used as a prognosis marker.

Invivo partial cellular reprogramming enhances liver plasticity and regeneration.

Mammals have limited regenerative capacity, whereas some vertebrates, like fish and salamanders, are able to regenerate their organs efficiently. The regeneration in these species depends on cell dedifferentiation followed by proliferation. We generate a mouse model that enables the inducible expression of the four Yamanaka factors (Oct-3/4, Sox2, Klf4, and c-Myc, or 4F) specifically in hepatocytes. Transient invivo 4F expression induces partial reprogramming of adult hepatocytes to a progenitor state and concomitantly increases cell proliferation. This is indicated by reduced expression of differentiated hepatic-lineage markers, an increase in markers of proliferation and chromatin modifiers, global changes in DNA accessibility, and an acquisition of liver stem and progenitor cell markers. Functionally, short-term expression of 4F enhances liver regenerative capacity through topoisomerase2-mediated partial reprogramming. Our results reveal that liver-specific 4F expression invivo induces cellular plasticity and counteracts liver failure, suggesting that partial reprogramming may represent an avenue for enhancing tissue regeneration.

Design, Synthesis, and Cytotoxicity and Topoisomerase I/IIα Inhibition Activity of Pyrazolo[4,3-f]quinoline Derivatives.

With the several targets of cancer treatment, inhibition of DNA topoisomerase activity is one of the well-known focuses in cancer chemotherapy. Here, we describe the design and synthesis of a novel series of pyrazolo[4,3-f]quinolines with potential anticancer/topoisomerase inhibition activity. Forty newly designed pyrazolo[4,3-f]quinoline derivatives were synthesized via inverse imino Diels–Alder reaction. The antiproliferative activity of the synthesized derivatives was initially measured in the human NUGC-3 cancer cell line. Then, the selected compounds 1B, 1C, 1M, 2A, 2D, 2E, 2F, and 2R with higher activity among tested compounds were screened against six cancer cell lines, including ACHN, HCT-15, MM231, NCI-H23, NUGC-3, and PC-3. The results demonstrated that the compounds 1M, 2E, and 2P were most effective in all cancer cell lines exhibiting GI50 below 8 µM. Among them, 2E showed an equivalent inhibition pattern of topoisomerase IIα activity to that of etoposide, positive control at a 100 µM dose.

OVERVIEW OF MITOXANTRONE-A POTENTIAL CANDIDATE FOR TREATMENT OF BREAST CANCER

Anthraquinones are one of the popular classes of aromatic compounds which possess potential anticancer properties by suppressing the nucleic acid formation and proteins essential to the survival of cancerous cells. Mitoxantrone (MT) is an antibiotic and antineoplastic agent belonging to the anthracycline class of compounds which exhibit minimal incident of drug resistance. It is a synthetic anticancer drug, bound to enzyme topoisomerase IIα inhibitor, and intercalates DNA topoisomerase IIα, preventing re-ligations in DNA strands fragmentation and disruption of DNA repair. The expression of this enzyme was used tumor cells marker because of its key function in cell proliferation. The cleavable complex of topoisomerase IIα is hypothesized to damage the DNA and may enhance apoptosis in tumor cell proliferation. The susceptibility of cells to mitoxantrone is associated with cell topoisomerase II α protein and lowered resistance in breast cancer line cell lines to topoisomerase IIα inhibitors. MT is an ABC-transporter in breast cancer, also designated to be associated with “Breast cancer resistance protein” (BCRP) and it is also a cell cycle non-specific anti-cancer drug and P-glycoprotein substrate. Multiple drug resistance is one of the major drawbacks of this drug which can be avoided by reducing the efflux of the drug from cancer cells by formulating drug by using lipophilic carriers. This manuscript discusses about MT's source, chemistry, physicochemical properties, anti-cancer effects of mitoxantrone and possible pathways, Mitoxantrone targeting topoisomerase II inhibitor for cancer therapy and its mechanism, Various Nano formulation development strategy, toxicity profile, and a few patents related information.

The coordination modes of (thio)semicarbazone copper(II) complexes strongly modulate the solution chemical properties and mechanism of anticancer activity

Thiosemicarbazones are promising candidates for anticancer therapy and their mechanism of action is often linked to their metal chelating ability. In this study, five (thio)semicarbazones with different donor sets (NNS, NNO, ONS, ONO) were selected and their behaviour in aqueous solution, the stability of their copper(II) complexes in addition to their cytotoxicity, DNA-binding, DNA cleavage ability and inhibition of topoisomerase IIα were investigated and compared. We aimed to reveal relationships between the structural variations, the significantly different physico-chemical properties, solution speciation and biological activity. The cytotoxicity of the ligands did not show correlation with the solubility, lipophilicity and permeability; and the decreased activity of the oxygen donor containing compounds was explained by their stronger preference towards chelation of iron(III) over iron(II). Meanwhile, among the copper complexes the most lipophilic species with the highest stability and membrane permeability exhibited the highest cytotoxicity. The studied copper(II) complexes interact with DNA, and reaction with glutathione led to heavy DNA cleavage in the case of the highly stable complexes which could be reduced in a reversible reaction with moderate rate. All the tested copper complexes inhibited topoisomerase IIα, however, this property of the complexes with low stability is most probably linked to the liberated free copper(II).

Expanding the Study of the Cytotoxicity of Incomptines A and B against Leukemia Cells.

Heliangolide-type sesquiterpene lactones (HTSLs) are phytocompounds with several pharmacological activities including cytotoxic and antitumor activity. Both bioactivities are related to an α-methylene-γ-lactone moiety and an ester group on carbon C-8 in the sesquiterpene lactone (SL) structure. Two HTSLs, incomptines A (AI) and B (IB) isolated from Decachaeta incompta, were evaluated for their cytotoxic activity on three leukemia cell lines: HL-60, K-562, and REH cells. Both compounds were subjected to a molecular docking study using target proteins associated with cancer such as topoisomerase IIα, topoisomerase IIβ, dihydrofolate reductase, methylenetetrahydrofolate dehydrogenase, and Bcl-2-related protein A1. Results show that IA and IB exhibit cytotoxic activity against all cell lines used. The CC50 value of IA was 2–4-fold less than etoposide and methotrexate, two anticancer drugs used as positive controls. The cytotoxic activity of IB was close to that of etoposide and methotrexate. The molecular docking analysis showed that IA and IB have important interaction on all targets used. These findings suggest that IA and IB may serve as scaffolds for the development of new treatments for different types of leukemia.

Sister chromatids separate during anaphase in a three-stage program as directed by interaxis bridges

During mitosis, from late prophase onward, sister chromatids are connected along their entire lengths by axis-linking chromatin/structure bridges. During prometaphase/metaphase, these bridges ensure that sister chromatids retain a parallel, paranemic relationship, without helical coiling, as they undergo compaction. Bridges must then be removed during anaphase. Motivated by these findings, the present study has further investigated the process of anaphase sister separation. Morphological and functional analyses of mammalian mitoses reveal a three-stage pathway in which interaxis bridges play a prominent role. First, sister chromatid axes globally separate in parallel along their lengths, with concomitant bridge elongation, due to intersister chromatin pushing forces. Sister chromatids then peel apart progressively from a centromere to telomere region(s), step-by-step. During this stage, poleward spindle forces dramatically elongate centromere-proximal bridges, which are then removed by a topoisomerase IIα–dependent step. Finally, in telomere regions, widely separated chromatids remain invisibly linked, presumably by catenation, with final separation during anaphase B. During this stage increased separation of poles and/or chromatin compaction appear to be the driving force(s). Cohesin cleavage licenses these events, likely by allowing bridges to respond to imposed forces. We propose that bridges are not simply removed during anaphase but, in addition, play an active role in ensuring smooth and synchronous microtubule-mediated sister separation. Bridges would thereby be the topological gatekeepers of sister chromatid relationships throughout all stages of mitosis.

A Novel Copper(II) Indenoisoquinoline Complex Inhibits Topoisomerase I, Induces G2 Phase Arrest, and Autophagy in Three Adenocarcinomas.

Topoisomerases, targets of inhibitors used in chemotherapy, induce DNA breaks accumulation leading to cancer cell death. A newly synthesized copper(II) indenoisoquinoline complex WN197 exhibits a cytotoxic effect below 0.5 µM, on MDA-MB-231, HeLa, and HT-29 cells. At low doses, WN197 inhibits topoisomerase I. At higher doses, it inhibits topoisomerase IIα and IIβ, and displays DNA intercalation properties. DNA damage is detected by the presence of γH2AX. The activation of the DNA Damage Response (DDR) occurs through the phosphorylation of ATM/ATR, Chk1/2 kinases, and the increase of p21, a p53 target. WN197 induces a G2 phase arrest characterized by the unphosphorylated form of histone H3, the accumulation of phosphorylated Cdk1, and an association of Cdc25C with 14.3.3. Cancer cells die by autophagy with Beclin-1 accumulation, LC3-II formation, p62 degradation, and RAPTOR phosphorylation in the mTOR complex. Finally, WN197 by inhibiting topoisomerase I at low concentration with high efficiency is a promising agent for the development of future DNA damaging chemotherapies.

Prediction of recurrence from metabolites and expression of TOP2A and EZH2 in prostate cancer patients treated with radiotherapy.

The dual upregulation of TOP2A and EZH2 gene expression has been proposed as a biomarker for recurrence in prostate cancer patients to be treated with radical prostatectomy. A low tissue level of the metabolite citrate has additionally been connected to aggressive disease and recurrence in this patient group. However, for radiotherapy prostate cancer patients, few prognostic biomarkers have been suggested. The main aim of this study was to use an integrated tissue analysis to evaluate metabolites and expression of TOP2A and EZH2 as predictors for recurrence among radiotherapy patients. From 90 prostate cancer patients (56 received neoadjuvant hormonal treatment), 172 transrectal ultrasound-guided (TRUS) biopsies were collected prior to radiotherapy. Metabolic profiles were acquired from fresh frozen TRUS biopsies using high resolution-magic angle spinning MRS. Histopathology and immunohistochemistry staining for TOP2A and EZH2 were performed on TRUS biopsies containing cancer cells (n = 65) from 46 patients, where 24 of these patients (n = 31 samples) received hormonal treatment. Eleven radical prostatectomy cohorts of a total of 2059 patients were used for validation in a meta-analysis. Among radiotherapy patients with up to 11 years of follow-up, a low level of citrate was found to predict recurrence, p = 0.001 (C-index = 0.74). Citrate had a higher predictive ability compared with individual clinical variables, highlighting its strength as a potential biomarker for recurrence. The dual upregulation of TOP2A and EZH2 was suggested as a biomarker for recurrence, particularly for patients not receiving neoadjuvant hormonal treatment, p = 0.001 (C-index = 0.84). While citrate was a statistically significant biomarker independent of hormonal treatment status, the current study indicated a potential of glutamine, glutamate and choline as biomarkers for recurrence among patients receiving neoadjuvant hormonal treatment, and glucose among patients not receiving neoadjuvant hormonal treatment. Using an integrated approach, our study shows the potential of citrate and the dual upregulation of TOP2A and EZH2 as biomarkers for recurrence among radiotherapy patients.

A new bio-active asymmetric-Schiff base: synthesis and evaluation of calf thymus DNA interaction, topoisomerase IIα inhibition, in vitro antiproliferative activity, SEM analysis and molecular docking studies

In this paper, the asymmetric-Schiff base 2-(4-(2-hydroxybenzylideneamino)benzylideneamino)benzoic acid (SB-2) was newly synthesized and characterized by various spectroscopic methods. The interaction of SB-2 with calf thymus DNA was investigated by UV–vis, fluorescence spectroscopy and molecular docking methods. It was determined that SB-2 effectively binds to DNA via the intercalation mode. DNA electrophoretic mobility experiments displayed that topoisomerase IIα could not cleave pBR322 plasmid DNA in the presence of SB-2, confirming that the Schiff base acts as a topo II suppressor. In the molecular docking studies, SB-2 was found to show an affinity for both the DNA-topoisomerase IIα complex and the DNA. In vitro antiproliferative activity of SB-2 was screened against HT-29 (colorectal) and HeLa (cervical) human tumor cell lines by MTT assay. SB-2 diminished the cell viability in a concentration- and incubation time-dependent manner. The ability of SB-2 to measure DNA damage in tumor cells was evaluated with cytokinesis-block micronucleus assay after incubation 24 h and 48 h. Light and scanning electron microscopy experiments of tumor cells demonstrated an incubation time-dependent increase in the proportion of apoptotic cells (nuclear condensation and apoptotic bodies) suggesting that autophagy and apoptosis play a role in the death of cells. Based on the obtained results, it may be considered that SB-2 is a candidate for DNA-targeting antitumor drug. Communicated by Ramaswamy H. Sarma

Predictive and Prognostic Significance of mRNA Expression and DNA Copies Aberrations of ERCC1, RRM1, TOP1, TOP2A, TUBB3, TYMS, and GSTP1 Genes in Patients with Breast Cancer.

Increasingly, many researchers are focusing on the sensitivity in breast tumors (BC) to certain chemotherapy drugs and have personalized their research based on the assessment of this sensitivity. One such personalized approach is to assess the chemotherapy’s gene expression, as well as aberrations in the number of DNA copies—deletions and amplifications with the ability to have a significant effect on the gene’s activity. Thus, the aim of this work was to study the predictive and prognostic significance of the expression and chromosomal aberrations of eight chemosensitivity genes in breast cancer patients. Material and methods. The study involved 97 patients with luminal B breast cancer IIB–IIIB stages. DNA and RNA were isolated from samples of tumor tissue before and after treatment. Microarray analysis was performed for all samples on high-density microarrays (DNA chips) of Affymetrix (USA) CytoScanTM HD Array and Clariom™ S Assay, human. Detection of expression level of seven chemosensitivity genes—RRM1, ERCC1, TOP1, TOP2a, TUBB3, TYMS, and GSTP1—was performed using PCR real-time (RT-qPCR). Results. The expression of the RRM1 (AC scheme), TOP2α, TYMS, and TUBB3 genes in patients with an objective response to treatment (complete and partial regression) is higher than in patients with stabilization and progression (p < 0.05). According to our results, the presence of a high level of GSTP1 in a tumor biopsy is associated with the low efficiency of the NAC CP scheme (p = 0.05). The presence of RRM1 deletion is associated with complete and partial regression, as for the TOP1 and TUBB3 genes (p < 0.05). Higher rates of metastatic survival are associated with a high level of expression and amplification of the GSTP1 gene (log-rank test p = 0.02 and p = 0.05). Conclusion. Thus, a complex assessment of the chemotherapy’s gene expression is important not only for understanding the heterogeneity and molecular biology of breast cancer but also to obtain a more accurate disease prognosis.

Topoisomerase IIα inhibitory and antiproliferative activity of dihydroxylated 2,6-diphenyl-4-fluorophenylpyridines: Design, synthesis, and structure-activity relationships

A new series of fifty-four 2-phenol-4-aryl-6-hydroxyphenylpyridines containing fluorophenyl, trifluoromethylphenyl, and trifluoromethoxy phenyl groups were synthesized and tested for topoisomerase IIα inhibitory and antiproliferative activity against different cancer cell lines in an attempt to look into topoisomerase IIα-targeted prospective anticancer agents to counter the limitations of available treatment options. When compared to positive controls, several compounds 11–12, 37, 50, and 51 showed high antiproliferative activity, while several 4-fluorophenyl substituted compounds 13–14 and 18 showed strong topoisomerase IIα inhibition. Surprisingly, most of the compounds had a significant antiproliferative effect on the HCT15 colorectal adenocarcinoma and T47D breast cancer cell lines. Moreover, compound 12 with para-fluorophenyl at the 4-position and meta-phenolic groups at the 2- and 6-positions inhibited proliferating HeLa cervix adenocarcinoma cells with an IC50 value of 1.28 μM. Based on biological results, the structure–activity relationships of the synthesized derivatives emphasized the significance of 4-trifluoromethoxyphenyl groups for strong antiproliferative activity and 4-fluorophenyl groups for strong topo IIα inhibition. Furthermore, meta- and para-phenolic groups at the 2- and 4-positions are favorable for strong topo IIα inhibitory and antiproliferative activity. The research findings provide insight into the effect of different fluorine functionalities in the discovery of novel topoisomerase IIα-targeted anticancer agents.

Identification of a novel catalytic inhibitor of topoisomerase II alpha that engages distinct mechanisms in p53wt or p53-/- cells to trigger G2/M arrest and senescence.

We report a novel topoisomerase IIα inhibitor, mercaptopyridine oxide (MPO), which induces G2/M arrest and senescence with distinctly different cell cycle regulators (p21 or p14ARF) in HCT116p 53WT and HCT116 p53-/- cells, respectively. MPO treatment induced defective topoisomerase IIα-mediated decatenation process and inhibition of the enzyme's catalytic activity that stalled entry into mitosis. Topoisomerase IIα inhibition was associated with ROS-mediated activation of ATM-Chk2 kinase axis in HCT116 p53WT cells, but not in HCT116 p53-/- cells displaying early Chk1 activation. Results suggest that E2F1 stabilization might link MPO-induced p53 phospho-activation in HCT116 p53WT cells or p14ARF induction in HCT116 p53-/- cells. Also, interaction between topoisomerase IIα and Chk1 was induced in both cell lines, which could be important for decatenation checkpoint activation, even upon p53 ablation. Notably, TCGA dataset analyses revealed topoisomerase IIα upregulation across a wide array of cancers, which was associated with lower overall survival. Corroborating that increased topoisomerase IIα expression might offer susceptibility to the novel inhibitor, MPO (5μM) induced strong inhibition in colony forming ability of pancreatic and hepatocellular cancer cell lines. These data highlight a novel topoisomerase IIα inhibitor and provide proof-of-concept for its therapeutic potential against cancers even with loss-of-function of p53.

Antibacterial and anticancer profiling of new benzocaine derivatives: Design, synthesis, and molecular mechanism of action

The need for new chemotherapeutics to overcome development of resistance merits research to discover new agents. Benzocaine derivatives are essential compounds in medicinal chemistry due to their various biological activities including antibacterial and anticancer activities. Therefore, this study focuses on the synthesis of new benzocaine derivatives 3a-e, 6, 7a and 7b, 8, 10-14, and 16a-d and their in vitro evaluation as antibacterial agents against gram +ve and -ve strains and as anticancer agents against HepG-2, HCT-116, and MCF-7 human cancer cell lines. The obtained results demonstrated that thiazolidines 6 and 7b showed higher antibacterial and anticancer activity in comparison with the reference drugs. In addition, 6 and 7b showed high potency as inhibitors toward their biological targets, that is DNA gyrase and human topoisomerase IIα, as compared to the reference standard drugs novobiocin and etoposide, respectively. Molecular docking demonstrated that both compounds could identify the active site of their target enzymes and develop effective binding interactions. Absorption, distribution, metabolism and elimination (ADME) and drug-likeness predictions of both compounds showed that they both have good ADME profiles and no structural alerts that might cause toxicity. Based on this, 6 and 7b could serve as lead compounds for the design of more potent antibacterial and anticancer agents.

Downregulation of topoisomerase 1 and 2 with acriflavine sensitizes bladder cancer cells to cisplatin-based chemotherapy.

Resistance to cisplatin is a major obstacle to effective treatment of bladder cancer (BC). The present study aimed to determine whether a combination of acriflavine (ACF) with cisplatin could potentiate the antitumor property of cisplatin against the BC cells. Furthermore, the molecular mechanism behind the anticancer action of ACF was considered. Two human BC cells (5637 and EJ138) contain mutated form of p53 was culture in standard condition. Cotreatment protocol (simultaneous combination of IC30 value of ACF + various dose of cisplatin for 72h) and pretreatment protocol (pretreatment with IC15 value of ACF for 24h + various dose of cisplatin for 48h) was used to determine the effect of ACF on the cells' sensitivity to main drug cisplatin. To assess the mechanism of action of ACF, real-time PCR was used to evaluate mRNA levels of hypoxia-inducible factor-1α (HIF-1α), Bax, Bcl-2, topoisomerase1 (TOP1) and topoisomerase 2 (TOP2A). Combination of ACF with cisplatin either as cotreatment or opretreatment protocol could significantly reduce the IC50 values of cisplatin as compared to the IC50 of cisplatin when use as a single drug. In addition, ACF could markedly decrease mRNA expression of TOP1 and TOP2A without changing the expression of HIF-1ɑ, Bax and Bcl-2. Our findings indicate that combination of cisplatin with ACF was able to significantly enhance the sensitivity of BC cells to cisplatin. The antitumor activity of ACF is exerted through the downregulation of TOP1 and TOP2A genes expression. ACF may serve as an adjuvant to boost cisplatin-based chemotherapy.

Bioinformatics screening the novel and promising targets of curcumin in hepatocellular carcinoma chemotherapy and prognosis

BackgroundThe aim of present study was to screen the novel and promising targets of curcumin in hepatocellular carcinoma diagnosis and chemotherapy.MethodsPotential targets of curcumin were screened from SwissTargetPrediction, ParmMapper and drugbank databases. Potential aberrant genes of hepatocellular carcinoma were screened from Genecards databases. Fifty paired hepatocellular carcinoma patients’ gene expression profiles from the GEO database were used to test potential targets of curcumin. Besides, GO analysis, KEGG pathway enrichment analysis and PPI network construction were used to explore the underlying mechanism of candidate hub genes. ROC analysis and Kaplan-Meier analysis were used to evaluate the diagnostic and prognostic value of candidate hub genes, respectively. Real-time PCR was used to verify the results of bioinformatics analysis.ResultsBioinformatics analysis results suggested that AURKA, CDK1, CCNB1, TOP2A, CYP2B6, CYP2C9, and CYP3A4 genes served as candidate hub genes. AURKA, CDK1, CCNB1 and TOP2A were significantly upregulated and correlated with poor prognosis in hepatocellular carcinoma, AUC values of which were 95.7, 96.9, 98.1 and 96.1% respectively. There was not significant correlation between the expression of CYP2B6 and prognosis of hepatocellular carcinoma, while CYP2C9 and CYP3A4 genes were significantly downregulated and correlated with poor prognosis in hepatocellular carcinoma. AUC values of CYP2B6, CYP2C9, and CYP3A4 were 96.0, 97.0 and 88.0% respectively. In vitro, we further confirmed that curcumin significantly downregulated the expression of AURKA, CDK1, and TOP2A genes, while significantly upregulated the expression of CYP2B6, CYP2C9, and CYP3A4 genes.ConclusionsOur results provided a novel panel of AURKA, CDK1, TOP2A, CYP2C9, and CYP3A4 candidate genes for curcumin related chemotherapy of hepatocellular carcinoma.

Recurrent mutations in topoisomerase IIα cause a previously undescribed mutator phenotype in human cancers

Topoisomerases nick and reseal DNA to relieve torsional stress associated with transcription and replication and to resolve structures such as knots and catenanes. Stabilization of the yeast Top2 cleavage intermediates is mutagenic in yeast, but whether this extends to higher eukaryotes is less clear. Chemotherapeutic topoisomerase poisons also elevate cleavage, resulting in mutagenesis. Here, we describe p.K743N mutations in human topoisomerase hTOP2α and link them to a previously undescribed mutator phenotype in cancer. Overexpression of the orthologous mutant protein in yeast generated a characteristic pattern of 2- to 4-base pair (bp) duplications resembling those in tumors with p.K743N. Using mutant strains and biochemical analysis, we determined the genetic requirements of this mutagenic process and showed that it results from trapping of the mutant yeast yTop2 cleavage complex. In addition to 2- to 4-bp duplications, hTOP2α p.K743N is also associated with deletions that are absent in yeast. We call the combined pattern of duplications and deletions ID_TOP2α. All seven tumors carrying the hTOP2α p.K743N mutation showed ID_TOP2α, while it was absent from all other tumors examined (n = 12,269). Each tumor with the ID_TOP2α signature had indels in several known cancer genes, which included frameshift mutations in tumor suppressors PTEN and TP53 and an activating insertion in BRAF. Sequence motifs found at ID_TOP2α mutations were present at 80% of indels in cancer-driver genes, suggesting that ID_TOP2α mutagenesis may contribute to tumorigenesis. The results reported here shed further light on the role of topoisomerase II in genome instability.

A loop extrusion-independent mechanism contributes to condensin I-mediated chromosome shaping.

Condensin I is a five-subunit protein complex that is central to mitotic chromosome assembly in eukaryotic cells. Despite recent progress, its molecular mechanisms of action remain to be fully elucidated. By using Xenopus egg extracts as a functional assay, we find that condensin I complexes harboring mutations in its kleisin subunit CAP-H produce chromosomes with confined axes in the presence of topoisomerase IIα (topo IIα) and highly compact structures (termed "beans") with condensin-positive central cores in its absence. The bean phenotype depends on the SMC ATPase cycle and can be reversed by subsequent addition of topo IIα. The HEAT repeat subunit CAP-D2, but not CAP-G, is essential for the bean formation. Notably, loop extrusion activities of the mutant complexes cannot explain the chromosomal defects they exhibit in Xenopus egg extracts, implying that a loop extrusion-independent mechanism contributes to condensin I-mediated chromosome assembly and shaping. We provide evidence that condensin-condensin interactions underlie these processes.

Study on the expression of TOP2A in hepatocellular carcinoma and its relationship with patient prognosis

BackgroundHepatocellular carcinoma (HCC) is a primary liver cancer with a high mortality rate. However, the molecular mechanism of HCC formation remains to be explored and studied.ObjectiveTo investigate the expression of TOP2A in hepatocellular carcinoma (HCC) and its prognosis.MethodsThe data set of hepatocellular carcinoma was downloaded from GEO database for differential gene analysis, and hub gene was identified by Cytoscape. GEPIA was used to verify the expression of HUB gene and evaluate its prognostic value. Then TOP2A was selected as the research object of this paper by combining literature and clinical sample results. Firstly, TIMER database was used to study TOP2A, and the differential expression of TOP2A gene between normal tissues and cancer tissues was analyzed, as well as the correlation between TOP2A gene expression and immune infiltration of HCC cells. Then, the expression of top2a-related antibodies was analyzed using the Human Protein Atlas database, and the differential expression of TOP2A was verified by immunohistochemistry. Then, SRTING database and Cytoscape were used to establish PPI network for TOP2A and protein–protein interaction analysis was performed. The Oncomine database and cBioPortal were used to express and identify TOP2A mutation-related analyses. The expression differences of TOP2A gene were identified by LinkedOmics, and the GO and KEGG pathways were analyzed in combination with related genes. Finally, Kaplan–Meier survival analysis was performed to analyze the clinical and prognosis of HCC patients.ResultsTOP2A may be a new biomarker and therapeutic target for hepatocellular carcinoma.

Synthesis, in silico molecular docking analysis, pharmacokinetic properties and evaluation of antibacterial and antioxidant activities of fluoroquinolines

BackgroundQuinolines have demonstrated various biological activities such as antimalarial, antibacterial and anticancer. Hence, compounds with such scaffold have been used as lead in drug development. This project is, therefore, aimed to synthesis and evaluates some biological activities of quinoline analogs.Methods2-Chloro-7-fluoroquinoline-3-carbaldehydes were synthesized by the application of Vilsmeier–Haack reaction. The chlorine in the fluoroquinoline-3-carbaldehyde was replaced with various nucleophiles. The aldehyde functional group was also converted to carboxylic acid and imine groups using oxidizing agent and various amines, respectively. The structures of the compounds synthesized were characterized by spectroscopic methods. Disc diffusion and DPPH assays were used to evaluate the antibacterial and antioxidant activities, respectively. The in silico molecular docking analysis of the synthesized compounds were done using AutoDock Vina against E. coli DNA Gyrase B and human topoisomerase IIα. The drug likeness properties were assessed using SwissADME and PreADMET.ResultsNine novel quinoline derivatives were synthesized in good yields. The in vitro antibacterial activity of the synthesized compounds was beyond 9.3 mm inhibition zone (IZ). Compounds 4, 5, 6, 7, 8, 10, 15, and 16 exhibited activity against E. coli, P. aeruginosa, S. aureus and S. pyogenes with IZ ranging from 7.3 ± 0.67 to 15.3 ± 0.33 mm at 200 μg/mL. Compound 9 displayed IZ against three of the bacterial strains except S. aureus. The IC50 for the radical scavenging activity of the synthesized compounds were from 5.31 to 16.71 μg/mL. The binding affinities of the synthesized compounds were from − 6.1 to − 7.2 kcal/mol against E. coli DNA gyrase B and − 6.8 to − 7.4 kcal/mol against human topoisomerase IIα. All of the synthesized compounds obeyed Lipinski’s rule of five without violation.ConclusionCompounds 4, 5, 6, 7, 8, 10, 15, and 16 displayed activity against Gram positive and Gram negative bacterial strains indicating that these compounds might be used as broad spectrum bactericidal activity. Compound 8 (13.6 ± 0.22 mm) showed better IZ against P. aeruginosa compared with ciprofloxacin (10.0 ± 0.45 mm) demonstrating the potential of this compound as antibacterial agent against this strain. Compounds 5, 6, 7, 8, 9 and 10 showed comparable binding affinities in their in silico molecular docking analysis against E. coli DNA gyrase B. All of the synthesized compounds also obeyed Lipinski’s rule of five without violation which suggests these compounds as antibacterial agents for further study. Compounds 7 and 8 were proved to be a very potent radical scavenger with IC50 values of 5.31 and 5.41 μg/mL, respectively. Compound 5, 6, 8, 10 and 16 had comparable binding affinity against human topoisomerase IIα suggesting these compounds as a possible candidate for anticancer drugs.