Mitotic Replication Research Articles

A Method for Physical Analysis of Recombination Intermediates in Saccharomyces cerevisiae.

Meiosis is a process through which diploid cells divide into haploid cells, thus promoting genetic diversity. This diversity arises from the formation of genetic crossovers (COs) that repair DNA double-strand breaks (DSBs), through homologous recombination (HR). Deficiencies in HR can lead to chromosomal abnormality resulting from chromosomal nondisjunction, and genetic disorders. Therefore, investigating the mechanisms underlying effective HR is crucial for reducing genome instability. Budding yeast serves as an ideal model for studying HR mechanisms due to its amenability to gene modifications and the ease of inducing synchronized meiosis to yield four spores. During meiosis, at the DNA level, programmed DSBs are repaired as COs or non-crossovers (NCOs) through structural alterations in the nascent D-loop, involving single-end invasions(SEIs) and double-Holliday junctions(dHJs). This repair occurs using homologous templates rather than sister templates. This protocol, using Southern blotting, allows for the analysis and monitoring of changes in DNA structures in the recombination process. One-dimensional (1D) gel electrophoresis is employed to detect DSBs, COs, and NCOs, while two-dimensional (2D) gel electrophoresis is utilized to identify joint molecules (JMs). Therefore, physical analysis is considered the most effective method for investigating the HR mechanism. Our protocol provides more comprehensive information than previous reports by introducing conditions for obtaining a greater number of cells from synchronized yeast and a method that can analyze not only meiotic/mitotic recombination but also mitotic replication.

Polo-Like Kinase 2: From Principle to Practice.

Polo-like kinase (PLK) 2 is an evolutionarily conserved serine/threonine kinase that shares the n-terminal kinase catalytic domain and the C-terminal Polo Box Domain (PBD) with other members of the PLKs family. In the last two decades, mounting studies have focused on this and tried to clarify its role in many aspects. PLK2 is essential for mitotic centriole replication and meiotic chromatin pairing, synapsis, and crossing-over in the cell cycle; Loss of PLK2 function results in cell cycle disorders and developmental retardation. PLK2 is also involved in regulating cell differentiation and maintaining neural homeostasis. In the process of various stimuli-induced stress, including oxidative and endoplasmic reticulum, PLK2 may promote survival or apoptosis depending on the intensity of stimulation and the degree of cell damage. However, the role of PLK2 in immunity to viral infection has been studied far less than that of other family members. Because PLK2 is extensively and deeply involved in normal physiological functions and pathophysiological mechanisms of cells, its role in diseases is increasingly being paid attention to. The effect of PLK2 in inhibiting hematological tumors and fibrotic diseases, as well as participating in neurodegenerative diseases, has been gradually recognized. However, the research results in solid organ tumors show contradictory results. In addition, preliminary studies using PLK2 as a disease predictor and therapeutic target have yielded some exciting and promising results. More research will help people better understand PLK2 from principle to practice.

Identification of Key Biomarkers and Pathways in Small-Cell Lung Cancer Using Biological Analysis.

Background Small-cell lung cancer (SCLC) is a major cause of carcinoma-related deaths worldwide. The aim of this study was to identify the key biomarkers and pathways in SCLC using biological analysis. Methods Key genes involved in the development of SCLC were identified by downloading three datasets from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened using the GEO2R online analyzer; for the functional annotation and pathway enrichment analysis of genes, Funrich software was used. Construction of protein-to-protein interaction (PPI) networks was accomplished using the Search Tool for the Retrieval of Interacting Genes (STRING), and network visualization and module identification were performed using Cytoscape. Results A total of 268 DEGs were ultimately obtained. The enriched functions and pathways of the upregulated DEGs included cell cycle, mitotic, and DNA replication, and the downregulated DEGs were enriched in epithelial-to-mesenchymal transition, serotonin degradation, and noradrenaline. Analysis of significant modules demonstrated that the upregulated genes are primarily concentrated in functions related to cell cycle and DNA replication. Kaplan-Meier analysis of hub genes revealed that they may promote the carcinogenesis and progression of SCLC. The result of ONCOMINE demonstrated that these 10 hub genes were significantly overexpressed in SCLC compared with normal samples. Conclusion Identification of the molecular functions and signaling pathways of participating DEGs can deepen the current understanding of the molecular mechanisms of SCLC. The knowledge gained from this work may contribute to the development of treatment options and improve the prognosis of SCLC in the future.

Mind the replication gap.

Unlike bacteria, mammalian cells need to complete DNA replication before segregating their chromosomes for the maintenance of genome integrity. Thus, cells have evolved efficient pathways to restore stalled and/or collapsed replication forks during S-phase, and when necessary, also to delay cell cycle progression to ensure replication completion. However, strong evidence shows that cells can proceed to mitosis with incompletely replicated DNA when under mild replication stress (RS) conditions. Consequently, the incompletely replicated genomic gaps form, predominantly at common fragile site regions, where the converging fork-like DNA structures accumulate. These branched structures pose a severe threat to the faithful disjunction of chromosomes as they physically interlink the partially duplicated sister chromatids. In this review, we provide an overview discussing how cells respond and deal with the under-replicated DNA structures that escape from the S/G2 surveillance system. We also focus on recent research of a mitotic break-induced replication pathway (also known as mitotic DNA repair synthesis), which has been proposed to operate during prophase in an attempt to finish DNA synthesis at the under-replicated genomic regions. Finally, we discuss recent data on how mild RS may cause chromosome instability and mutations that accelerate cancer genome evolution.

Timing Is Everything: Misincorporation of 8oxodG during Mitosis Is Lethal.

Exploiting universal cancer vulnerabilities has been used as an approach for developing targeted therapies. In this issue of Cancer Research, Rudd and colleagues show that the dual-functioning inhibitor TH588 potentiates the accumulation of reactive oxygen species during mitosis in cancer by disturbing mitotic progression and simultaneously inhibiting the hydrolysis of 8oxodGTP. This leads to increased incorporation of 8oxodG into the DNA during mitotic replication and increased toxicity. Understanding the mechanism of this inhibitor lays the groundwork for identifying cancer targets.See related article by Rudd et al., p. 3530.

Abstract 5123: Proteogenomic characterization reveals mitotic kinase and replication stress implicated in ovarian high-grade serous cancer

Abstract High-grade serous cancer (HGSC), the most prevalent histotype of ovarian cancer, has the lowest survival rates and is the leading cause of gynecological cancer-related deaths in the developed world. HGSC is characterized by the presence of nearly universal TP53 mutations, diverse and widespread chromosomal instability, and a general shortage of targetable driving mutations. The major clinical needs in HGSC include the identification of alternative therapeutic targets and an improved understanding of the mechanisms driving chromosomal heterogeneity. We prospectively collected 83 new ovarian HGSC samples and 20 normal precursor tissue samples (Fallopian tube, FT) for deep characterization at the genomic, transcriptomic, proteomic, and phosphoproteomic levels. We were also able to obtain cytobrush samples of Fallopian tube epithelium and provide the first extensive comparison of HGSC and FT proteomes and phosphoproteomes that used surgical specimens rather than cell lines. The ability to compare tumor and normal precursor tissues provided new biological insights regarding the role of increased proliferation in promoting replication stress in a DNA repair-deficient background, potentially explaining the high degree of chromosomal instability associated with HGSC. Our collection protocols were specifically designed to minimize the effect of ischemia on protein phosphorylation, which has been identified as a significant confounding variable. Thus, we were able to identify novel signaling interactions that would have been lost in the background of ischemic stress, most notably the activation of CDK4 and CDK7. Widespread increases in protein phosphorylation and pathway activation in tumors compared to normal tissues, particularly in the proliferation-associated CDK/RB and AURKA pathways that are targetable by FDA-approved inhibitors, provide a rational basis for the use of these therapeutics in ovarian cancer. Phosphosite-specific analysis of CDKs and FANCD was consistent with an elevated response to replication stress, potentially induced by proliferative signals. Additionally, pathway-level observations from the retrospective TCGA cohort were conserved in the prospective cohort, including histone acetylation marks associated with homologous repair deficiency. In addition to confirming key features of HGSC from previous proteogenomic study, analysis of prospectively collected HGSC samples provided significant new insights stemming from direct comparisons to normal precursor tissues; deep phosphoproteomics revealed new insights regarding the potential role of proliferation-induced replication stress in promoting the characteristic chromosomal instability of HGSC and suggested novel therapeutic targets for use in precision medicine trials. Citation Format: Jason McDermott, Osama Arshad, Vladislav Petyuk, Yi Fu, Marina Gritsenko, Chia-Feng Tsai, Samuel Payne, Mathangi Thiagarajan, Christopher Kinsinger, Ana Robles, Emily Boja, Henry Rodriguez, Daniel Chan, Bing Zhang, Zhen Zhang, Li Ding, Richard Smith, Tao Liu, Karin Rodland. Proteogenomic characterization reveals mitotic kinase and replication stress implicated in ovarian high-grade serous cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5123.

Rapid antigen diversification through mitotic recombination in the human malaria parasite Plasmodium falciparum

Malaria parasites possess the remarkable ability to maintain chronic infections that fail to elicit a protective immune response, characteristics that have stymied vaccine development and cause people living in endemic regions to remain at risk of malaria despite previous exposure to the disease. These traits stem from the tremendous antigenic diversity displayed by parasites circulating in the field. For Plasmodium falciparum, the most virulent of the human malaria parasites, this diversity is exemplified by the variant gene family called var, which encodes the major surface antigen displayed on infected red blood cells (RBCs). This gene family exhibits virtually limitless diversity when var gene repertoires from different parasite isolates are compared. Previous studies indicated that this remarkable genome plasticity results from extensive ectopic recombination between var genes during mitotic replication; however, the molecular mechanisms that direct this process to antigen-encoding loci while the rest of the genome remains relatively stable were not determined. Using targeted DNA double-strand breaks (DSBs) and long-read whole-genome sequencing, we show that a single break within an antigen-encoding region of the genome can result in a cascade of recombination events leading to the generation of multiple chimeric var genes, a process that can greatly accelerate the generation of diversity within this family. We also found that recombinations did not occur randomly, but rather high-probability, specific recombination products were observed repeatedly. These results provide a molecular basis for previously described structured rearrangements that drive diversification of this highly polymorphic gene family.

A 3D digital atlas of the Nicotiana tabacum root tip and its use to investigate changes in the root apical meristem induced by the Agrobacterium 6b oncogene.

Using the intrinsic Root Coordinate System (iRoCS) Toolbox, a digital atlas at cellular resolution has been constructed for Nicotiana tabacum roots. Mitotic cells and cells labeled for DNA replication with 5-ethynyl-2'-deoxyuridine (EdU) were mapped. The results demonstrate that iRoCS analysis can be applied to roots that are thicker than those of Arabidopsis thaliana without histological sectioning. A three-dimensional (3-D) analysis of the root tip showed that tobacco roots undergo several irregular periclinal and tangential divisions. Irrespective of cell type, rapid cell elongation starts at the same distance from the quiescent center, however, boundaries between cell proliferation and transition domains are cell-type specific. The data support the existence of a transition domain in tobacco roots. Cell endoreduplication starts in the transition domain and continues into the elongation zone. The tobacco root map was subsequently used to analyse root organization changes caused by the inducible expression of the Agrobacterium 6b oncogene. In tobacco roots that express the 6b gene, the root apical meristem was shorter and radial cell growth was reduced, but the mitotic and DNA replication indexes were not affected. The epidermis of 6b-expressing roots produced less files and underwent abnormal periclinal divisions. The periclinal division leading to mature endodermis and cortex3 cell files was delayed. These findings define additional targets for future studies on the mode of action of the Agrobacterium 6b oncogene.

GRIM-19 Restores Cervical Cancer Cell Senescence by Repressing hTERT Transcription.

High telomerase activity promotes tumor growth by stabilizing damaged chromosomes and their mitotic replication. Overactivation of telomerase activity has been reported in cervical cancer, a malignancy caused by high-risk human papillomaviruses (HR-HPVs). The HR-HPV E6 can activate hTERT promoter by interacting with E6AP or other binding proteins and by stabilizing the interaction between hTERT and E6AP. GRIM-19 is a novel tumor suppressor that affects multiple targets in a cell to regulate growth. We have previously reported the interaction of GRIM-19 with 18E6 and E6AP to disrupt the E6/E6AP complex and increase the autoubiquitination of E6AP. In this study, we characterized the interaction of GRIM-19 with 16E6 (an oncoprotein produced by HPV16) and identified the binding sites that mediate this interaction. We also found that GRIM-19 expression in cervical cancer cells could inhibit telomerase activity by inhibiting the transactivation of the hTERT promoter by E6, thereby promoting cervical cancer cell senescence. Moreover, we identified a negative correlation between GRIM-19 and hTERT expression in cervical cancer tissues. Suppression of GRIM-19 and induction of hTERT levels were associated with lymph node metastasis, advanced clinical stage, and poor prognosis. This study identified another important novel antitumor molecular link associated with GRIM-19 in the tumorigenesis.

DNA repair: The cell cycle flavours of repair.

The suppression of homologous recombination in G1 depends on BRCA1–PALB2–BRCA2 complex formation at sites of damage. In mitosis, DNA repair factors prevent the formation of DNA damage by facilitating mitotic replication.

Noncoding RNA NORAD Regulates Genomic Stability by Sequestering PUMILIO Proteins

Long noncoding RNAs (lncRNAs) have emerged as regulators of diverse biological processes. Here, we describe the initial functional analysis of a poorly characterized human lncRNA (LINC00657) that is induced after DNA damage, which we termed "noncoding RNA activated by DNA damage", or NORAD. NORAD is highly conserved and abundant, with expression levels of approximately 500-1,000 copies per cell. Remarkably, inactivation of NORAD triggers dramatic aneuploidy in previously karyotypically stable cell lines. NORAD maintains genomic stability by sequestering PUMILIO proteins, which repress the stability and translation of mRNAs to which they bind. In the absence of NORAD, PUMILIO proteins drive chromosomal instability by hyperactively repressing mitotic, DNA repair, and DNA replication factors. These findings introduce a mechanism that regulates the activity of a deeply conserved and highly dosage-sensitive family of RNA binding proteins and reveal unanticipated roles for a lncRNA and PUMILIO proteins in the maintenance of genomic stability.

DNA repair: The cell cycle flavours of repair.

The suppression of homologous recombination in G1 depends on BRCA1–PALB2–BRCA2 complex formation at sites of damage. In mitosis, DNA repair factors prevent the formation of DNA damage by facilitating mitotic replication.

Estimating rates of de novo infection and mitotic replication in HTLV-1 persistence: de novo infection continues after early infection

Human T-lymphotropic virus type-1 (HTLV-1) persists within hosts via de novo infection (infectious spread) and infected cell proliferation (mitotic spread), creating a population structure of multiple clones (infected cell populations with identical genomic proviral integration sites). However, the relative contributions of these mechanisms are unknown, and will determine the efficacy of antiretroviral therapy. The prevailing view is that infectious spread does not contribute to HTLV-1 proviral load after early infection. However, this notion is based on low-throughput and imprecise data on clonal integration site abundance and diversity. We recently used our high-throughput protocol that maps and quantifies the abundance of HTLV-1 integration sites to estimate a diversity of between 10^4 and 10^5 HTLV-1 T cell clones in the body of an asymptomatic carrier or patient with HAM/TSP. Since infectious spread establishes new clones, high clonal diversity implies substantial infectious spread. HTLV-1 clonal abundance varies within individual hosts by several orders of magnitude. Therefore quantifying within-host HTLV-1 dynamics requires mathematical modelling at multiple scales, and stochastic processes are necessary to describe the behaviour of small clones. Here we apply a hybrid model of deterministic and stochastic processes to time-series patient data, to estimate the relative contributions of infectious spread and mitotic spread. We find, contrary to previous belief that infectious spread persists during chronic infection, even after the proviral load has reached its set point. The risk of HTLV-1-associated malignant and inflammatory disease is strongly correlated with the proviral load: the load in turn is correlated with the total number of HTLV-1-infected clones, but not with the degree of oligoclonal proliferation. Our results therefore suggest that attempts to suppress de novo infection may reduce the risk of malignant transformation.

Evaluation of Possible Genotoxic Activity of Dirithromycin in Cultured Human Lymphocytes.

Dirithromycin antibiotic is a 14-membered lactone ring macrolide and is widely used in medicine to treat many different types of bacterial infections. In the present study, the possible genotoxicity of dirithromycin was evaluated in cultured human lymphocytes by using sister chromatid exchanges (SCEs), chromosome aberration (CA), and micronucleus (MN) tests and also cell proliferation kinetics such as mitotic index (MI), replication index (RI), and nuclear division index (NDI) were analyzed for cytotoxicity. Cell cultures were treated with four different concentrations of dirithromycin (37.75, 67.50, 125, and 250 µg/mL) for 24 and 48 h periods. Dirithromycin significantly induced SCE and MN frequency at all concentrations in both 24 and 48 h treated cells. In addition, CA level has been markedly increased in the cells treated with almost all concentrations of dirithromycin for 24 (except 37.75 µg/mL) and 48 h treatment periods as compared to control. However, MI, RI, and NDI values were not affected by the dirithromycin treatment (p > 0.05). The results of this study indicated that dirithromycin treatment caused genetic damage by increasing the level of cytogenetic endpoints, suggesting its genotoxic and mutagenic action on human lymphocytes in vitro.

Visualization of recombination-mediated damage bypass by template switching.

Template switching (TS) mediates damage-bypass via a recombination-related mechanism involving PCNA polyubiquitylation and Polymerase δ-dependent DNA synthesis. Using two-dimensional gel electrophoresis and electron microscopy, here we characterize TS intermediates arising in Saccharomyces cerevisiae at a defined chromosome locus, identifying five major families of intermediates. Single-stranded DNA gaps in the range of 150-200 nucleotides, and not DNA ends, initiate TS by strand invasion. This causes re-annealing of the parental strands and exposure of the non-damaged newly synthesized chromatid as template for replication by the other blocked nascent strand. Structures resembling double Holliday Junctions, postulated to be central double-strand break repair intermediates, but so far only visualized in meiosis, mediate late stages of TS, before being processed to hemicatenanes. Our results reveal the DNA transitions accounting for recombination-mediated DNA damage tolerance in mitotic cells and for replication under conditions of genotoxic stress.

Role and Function of Mitochondria

Mitochondrial diseases are a group of disorders caused by pathologic dysfunction of the mitochondrial respiratory chain. They present with a wide range of clinical expression. Although neurologic impairment is a common manifestation but they can affect other systems, either exclusively or in combination. Mitochondria are intracellular organelles found in almost all human cells. They are responsible for aerobic metabolism through oxidative phosphorylation, which leads to energy production in the form of adenosine triphosphate (ATP). Each human cell contains on average hundreds to thousands of mitochondria. The exception is mature red blood cells, which rely exclusively on anaerobic metabolism and contain no mitochondria. Mitochondria have four main compartments: 1. The outer membrane, 2.The intermembranous space, 3.The inner membrane, 4.The matrix. In addition to ATP generation through the respiratory chain, mitochondria perform multiple other metabolic functions, including pyruvate oxidation, the Krebs cycle, fatty acid oxidation, and amino acid metabolism. All of these tasks take place in the matrix. Although any abnormality in the above pathways could be technically designated as a mitochondrial disorder, only defects in the respiratory chain are traditionally referred to as primary mitochondrial diseases. The respiratory chain is composed of five enzyme complexes (complex I, II, III, IV, V) that are involved in receipt and transfer of electrons through these compartments .Oxidative phosphorylation takes place along the inner mitochondrial membrane, which contains the respiratory chain proteins. Mitochondria are under the dual control of mitochondrial DNA and nuclear DNA. Mitochondrial DNA has several characteristics that distinguish them from their nuclear counterparts. These include: Maternal inheritance, heteroplasmy (e.g. some pathologic DNA copy, mitochondria or cells mixed with healthy ones), threshold effect (A minimal number of mutated cells needed before respiratory chain and cellular dysfunction occur), Mitotic segregation (e.g. since organelles are randomly distributed at the time of cell division, a change in the amount of mutant DNA in a cell occurs and surpass its threshold, therefore clinical phenotype can be changed in a previously unaffected tissue). Post mitotic replication (Mitochondrial DNA replication is not linked to the cell cycle. This allows for post mitotic mitochondrial DNA replication in terminally differentiated cells such as neurons or muscle in response to specific stimuli (exercise, increased metabolic demand). This explains how the symptomatic threshold can be exceeded later in life in previously asymptomatic tissues). In contrast to mitochondrial DNA, nuclear DNA mutations affecting the mitochondria follow Mendelian genetics. Most of the nuclear genes that are Gholamreza ZAMANI MD

Comparative genotoxic and cytotoxic effects of the oral antidiabetic drugs sitagliptin, rosiglitazone, and pioglitazone in patients with type-2 diabetes: A cross-sectional, observational pilot study

This cross-sectional, observational pilot study was designed to investigate the frequency of different endpoints of genotoxicity (sister-chromatid exchange, total chromosome aberrations, and micronucleus formation) and cytotoxicity (mitotic index, replication index, and nuclear division index) in the peripheral lymphocytes of patients with type-2 diabetes treated with different oral anti-diabetic agents for 6 months. A total of 104 patients who met the American Diabetes Association criteria for type-2 diabetes were enrolled in the study. Of the 104 patients, 33 were being treated with sitagliptin (100mg/day), 25 with pioglitazone (30mg/day), 22 with rosiglitazone (4mg/day), and 24 with medical nutrition therapy (control group). The results for all the genotoxicity endpoints were significantly different across the four study groups. Post hoc analysis revealed that the genotoxicity observed in the sitagliptin group was significantly higher than that observed in the medical nutrition therapy group, but lower than that occurring in subjects who received thiazolidinediones. All of the three cytotoxicity endpoints were significantly lower in patients treated by oral anti-diabetic agents compared with those who received medical nutrition therapy. However, the three indexes did not differ significantly in the sitagliptin, rosiglitazone, and pioglitazone groups. Taken together, these pilot data indicate that sitagliptin and thiazolidinediones may exert genotoxic and cytotoxic effects in patients with type-2 diabetes. Further investigations are necessary to clarify the possible long-term differences between oral anti-diabetic drugs in terms of genotoxicity and cytotoxicity, and how these can modulate the risk of developing diabetic complications in general and cancer in particular.

Genotoxic effects of sulfur dioxide in human lymphocytes

Sulfur dioxide (SO2), which is used as food preservative in apricot sulfurization and several fabricated foods, is a common air pollutant. The aim of this study was to reveal the possible genotoxic effects of SO2 using in vitro human lymphocytes. The different endpoints of genotoxicity: sister chromatid exchange (SCE), micronuclei (MN) tests and cell growth kinetics such as mitotic index (MI) and replication index (RI) were studied. The cells were treated with 0.1, 0.5 and 1.0 ppm concentrations of SO2. It was shown that SO2 caused significant increases in the frequency of SCE and MN in the middle and high dosage groups and also induced mitotic delays and decreased MI and RI. In conclusion, the results have confirmed that SO2 has potent mutagenicity and it can cause genetic damage leading to a malignancy.

Genotoxic effects of tacrolimus on human lymphocyte cells

We designed in vitro study to determine possible genotoxic effects oftacrolimus (FK-506), which is used as a potent immunosuppressive drug, by using sister chromatid exchange (SCEs), chromosome aberration (CAs), micronuclei tests (MN) and cell growth kinetics such as mitotic index (MI) and replication index (RI) in human lymphocytes. The cells were treated with 5, 25, 50, and 100 ng/mL concentrations of tacrolimus, for 24 h and 48 h treatment periods. Tacrolimus induced CA and MN frequency at all concentrations for 24 and 48 h In additon, it induced the SCE at the highest concantration for 24 h and at 25 and 100 ng/mL for 48 h. Tacrolimus decreased MI at all concentrations (except 5 ng/mL) for all treatment periods. It also inhibited the RI at 50 and 100 ng/mL concentrations for 24 h and at all concentrations for 48 h. Treatments given with tacrolimus result in the enhance of the different endpoints ofgenotoxicity, suggesting its mutagenic action on lymphocytes in vitro.

In vitro cytogenetic effects of Hypericum heterophyllum in human peripheral blood lymphocytes

Hypericum species have been used in traditional medicine in Turkey for thousands of years. In order to determine the cytogenetic effects of Hypericum heterophyllum, human lymphocytes were incubated with the aqueous extracts. Mitotic index frequencies and replication index values were increased with increasing extract concentrations of H. heterophyllum. The results indicate the cytotoxic effects as well as proliferative effects and suggest that the extracts of the compounds exhibit cytotoxic properties as well as mitotic and proliferative properties.