Mitosis-targeted anti-cancer therapies: where they stand

MKI-1, a Novel Small-Molecule Inhibitor of MASTL, Exerts Antitumor and Radiosensitizer Activities Through PP2A Activation in Breast Cancer

Although MASTL (microtubule-associated serine/threonine kinase-like) is an attractive target for anticancer treatment, MASTL inhibitors with antitumor activity have not yet been reported. In this study, we have presented a novel MASTL inhibitor, MKI-1, identified through in silico screening and in vitro analysis. Our data revealed that MKI-1 exerted antitumor and radiosensitizer activities in in vitro and in vivo models of breast cancer. The mechanism of action of MKI-1 occurred through an increase in PP2A activity, which subsequently decreased the c-Myc protein content in breast cancer cells. Moreover, the activity of MKI-1 in the regulation of MASTL-PP2A was validated in a mouse oocyte model. Our results have demonstrated a new small-molecule inhibitor of MASTL, MKI-1, which exerts antitumor and radiosensitizer activities through PP2A activation in breast cancer in vitro and in vivo.

ARID2 is a pomalidomide-dependent CRL4CRBN substrate in multiple myeloma cells

The immunomodulatory drug (IMiD) thalidomide and its derivatives lenalidomide and pomalidomide are therapeutic agents used in the treatment of multiple myeloma. Although pomalidomide offers considerable clinical benefits to patients with lenalidomide-resistant multiple myeloma, the molecular mechanisms underlying its superior efficacy remain unclear. Here we show that ARID2, a component of the polybromo-associated BAF (PBAF) chromatin-remodeling complex, is a pomalidomide-induced neosubstrate of CRL4^CRBN. BRD7, another subunit of PBAF, is critical for pomalidomide-induced ARID2 degradation. ARID2 is involved in transcriptional regulation of pomalidomide target genes including MYC. Pomalidomide is more effective than lenalidomide in degrading ARID2 and is capable of inhibiting MYC expression and proliferation in lenalidomide-resistant cell lines. Notably, ARID2 expression is associated with a poor prognosis and is higher in chemoresistant minimal residual disease (MRD) populations, and in patients with relapsed/refractory multiple myeloma. These findings suggest that ARID2 is a promising target for overcoming lenalidomide resistance in patients with multiple myeloma.

Hydroxy-Propil-β-Cyclodextrin Inclusion Complexes of two Biphenylnicotinamide Derivatives: Formulation and Anti-Proliferative Activity Evaluation in Pancreatic Cancer Cell Models

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with poor outcomes largely due to its unique microenvironment, which is responsible for the low response to drugs and drug-resistance phenomena. This clinical need led us to explore new therapeutic approaches for systemic PDAC treatment by the utilization of two newly synthesized biphenylnicotinamide derivatives, PTA73 and PTA34, with remarkable antitumor activity in an in vitro PDAC model. Given their poor water solubility, inclusion complexes of PTA34 and PTA73 in Hydroxy-Propil-β-Cyclodextrin (HP-β-CD) were prepared in solution and at the solid state. Complexation studies demonstrated that HP-β-CD is able to form stable host–guest inclusion complexes with PTA34 and PTA73, characterized by a 1:1 apparent formation constant of 503.9 M⁻¹ and 369.2 M⁻¹, respectively (also demonstrated by the Job plot), and by an increase in aqueous solubility of about 150 times (from 1.95 µg/mL to 292.5 µg/mL) and 106 times (from 7.16 µg/mL to 762.5 µg/mL), in the presence of 45% w/v of HP-β-CD, respectively. In vitro studies confirmed the high antitumor activity of the complexed PTA34 and PTA73 towards PDAC cells, the strong G2/M phase arrest followed by induction of apoptosis, and thus their eligibility for PDAC therapy.

Molecular targets and anticancer activity of quinoline-chalcone hybrids: literature review

α,β-Unsaturated chalcone moieties and quinoline scaffolds play an important role in medicinal chemistry, especially in the identification and development of potential anticancer agents. The multi-target approach or hybridization is considered as a promising strategy in drug design and discovery. Hybridization may improve the affinity and potency while simultaneously decreasing the resistance and/or side effects. The conjugation of quinolines with chalcones has been a promising approach to the identification of potential anticancer agents. Most of these hybrids showed anticancer activities through the inhibition of tubulin polymerization, different kinases, topoisomerases, or by affecting DNA cleavage activity. Accordingly, this class of compounds can be classified based on their molecular modes of action. In this article, the quinolone-chalcone hybrids with potential anticancer activity have been reviewed. This class of compounds might be helpful for the design, discovery and development of new and potential multi-target anticancer agents or drugs.

Recent researches for dual Aurora target inhibitors in antitumor field

Non-infectious and chronic diseases such as malignant tumors are now one of the main causes of human death. Its occurrence is a multi-factor, multi-step complex process with biological characteristics such as cell differentiation, abnormal proliferation, uncontrolled growth, and metastasis. It has been found that a variety of human malignant tumors are accompanied by over-expression and proliferation of Aurora kinase, which causes abnormalities in the mitotic process and is related to the instability of the genome that causes tumors. Therefore, the use of Aurora kinase inhibitors to target tumors is becoming a research hotspot. However, in cancer, because of the complexity of signal transduction system and the participation of different proteins and enzymes, the anticancer effect of selective single-target drugs is limited. After inhibiting one pathway, signal molecules can be conducted through other pathways, resulting in poor therapeutic effect of single-target drug treatment. Multi-target drugs can solve this problem very well. It can regulate the various links that cause disease at the same time without completely eliminating the relationship between the signal transmission systems, and it is not easy to cause drug resistance. Currently, studies have shown that Aurora dual-target inhibitors generated with the co-inhibition of Aurora and another target (such as CDK, PLK, JAK2, etc.) have better therapeutic effects on tumors. In this paper, we reviewed the studies of dual Aurora inhibitors that have been discovered in recent years.

Targeting the oncogene LSF with either the small molecule inhibitor FQI1 or siRNA causes mitotic delays with unaligned chromosomes, resulting in cell death or senescence

BACKGROUND

The oncogene LSF (encoded by TFCP2) has been proposed as a novel therapeutic target for multiple cancers. LSF overexpression in patient tumors correlates with poor prognosis in particular for both hepatocellular carcinoma and colorectal cancer. The limited treatment outcomes for these diseases and disappointing clinical results, in particular, for hepatocellular carcinoma in molecularly targeted therapies targeting cellular receptors and kinases, underscore the need for molecularly targeting novel mechanisms. LSF small molecule inhibitors, Factor Quinolinone Inhibitors (FQIs), have exhibited robust anti-tumor activity in multiple pre-clinical models, with no observable toxicity.

METHODS

To understand how the LSF inhibitors impact cancer cell proliferation, we characterized the cellular phenotypes that result from loss of LSF activity. Cell proliferation and cell cycle progression were analyzed, using HeLa cells as a model cancer cell line responsive to FQI1. Cell cycle progression was studied either by time lapse microscopy or by bulk synchronization of cell populations to ensure accuracy in interpretation of the outcomes. In order to test for biological specificity of targeting LSF by FQI1, results were compared after treatment with either FQI1 or siRNA targeting LSF.

RESULTS

Highly similar cellular phenotypes are observed upon treatments with FQI1 and siRNA targeting LSF. Along with similar effects on two cellular biomarkers, inhibition of LSF activity by either mechanism induced a strong delay or arrest prior to metaphase as cells progressed through mitosis, with condensed, but unaligned, chromosomes. This mitotic disruption in both cases resulted in improper cellular division leading to multiple outcomes: multi-nucleation, apoptosis, and cellular senescence.

CONCLUSIONS

These data strongly support that cellular phenotypes observed upon FQI1 treatment are due specifically to the loss of LSF activity. Specific inhibition of LSF by either small molecules or siRNA results in severe mitotic defects, leading to cell death or senescence - consequences that are desirable in combating cancer. Taken together, these findings confirm that LSF is a promising target for cancer treatment. Furthermore, this study provides further support for developing FQIs or other LSF inhibitory strategies as treatment for LSF-related cancers with high unmet medical needs.

Image analysis of mechanistic protein biomarkers for the characterization of genotoxicants: Aneugens, clastogens, and reactive oxygen species inducers

The early detection of genotoxicity contributes to cutting-edge drug discovery and development, requiring effective identification of genotoxic hazards posed by drugs while providing mode of action (MoA) information in a high throughput manner. In other words, there is a need to complement standard genotoxicity testing according to the test battery given in ICH S2(R1) with new in vitro tools, thereby contributing to a more in-depth analysis of genotoxic effects. Here, we report on a proof-of-concept MoA approach based on post-translational modifications of proteins (PTMs) indicative of clastogenic and aneugenic effects in TK6 cells using imaging technology (with automated analysis). Cells were exposed in a 96-well plate format with a panel of reference (geno)toxic compounds and subsequently analyzed at 4 and 24 hr to detect dose-dependent changes in PTMs, relevant for mechanistic analysis. All tested compounds that interfere with the spindle apparatus yielded a BubR1 (S640) (3/3) and phospho-histone H3 (S28) (7/9) positive dose-response reflecting aneugenicity, whereas compounds inducing DNA double-strand-breaks were associated with positive FANCD2 (S1404) and 53BP1 (S1778) responses pointing to clastogenicity (2/3). The biomarker p53 (K373) was able to distinguish genotoxicants from non-genotoxicants (2/4), while the induction of reactive oxygen species (ROS), potentially causing DNA damage, was associated with a positive Nrf2 (S40) response (2/2). This work demonstrates that genotoxicants and non-genotoxicants induce different biomarker responses in TK6 cells which can be used for reliable classification into MoA groups (aneugens/clastogens/non-genotoxicants/ROS inducers), supporting a more in-depth safety assessment of drug candidates.

Cell-Cycle Cross Talk with Caspases and Their Substrates

Caspases play central roles in mediating both cell death and inflammation. It has more recently become evident that caspases also drive other biological processes. Most prominently, caspases have been shown to be involved in differentiation. Several stem and progenitor cell types rely on caspases to initiate and execute their differentiation processes. These range from neural and glial cells, to skeletal myoblasts and osteoblasts, and several cell types of the hematopoietic system. Beyond differentiation, caspases have also been shown to play roles in other "noncanonical" processes, including cell proliferation, arrest, and senescence, thereby contributing to the mechanisms that regulate tissue homeostasis at multiple levels. Remarkably, caspases directly influence the course of the cell cycle in both a positive and negative manner. Caspases both cleave elements of the cell-cycle machinery and are themselves substrates of cell-cycle kinases. Here we aim to summarize the breadth of interactions between caspases and cell-cycle regulators. We also highlight recent developments in this area.

Missing Selectivity of Targeted 4β-Phorbol Prodrugs Expected to be Potential Chemotherapeutics

Targeting cytotoxic 4β-phorbol esters toward cancer tissue was attempted by conjugating a 4β-pborbol derivative with substrates for the proteases prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) expressed in cancer tissue. The hydrophilic peptide moiety was hypothesized to prevent penetration of the prodrugs into cells and prevent interaction with PKC. Cleavage of the peptide in cancer tumors was envisioned to release lipophilic cytotoxins, which subsequently penetrate into cancer cells. The 4β-phorbol esters were prepared from 4β-phorbol isolated from Croton tiglium seeds, while the peptides were prepared by solid-phase synthesis. Cellular assays revealed activation of PKC by the prodrugs and efficient killing of both peptidase positive as well as peptidase negative cells. Consequently no selectivity for enzyme expressing cells was found.

Cancer-Targeting Nanoparticles for Combinatorial Nucleic Acid Delivery

Nucleic acids are a promising type of therapeutic for the treatment of a wide range of conditions, including cancer, but they also pose many delivery challenges. For efficient and safe delivery to cancer cells, nucleic acids must generally be packaged into a vehicle, such as a nanoparticle, that will allow them to be taken up by the target cells and then released in the appropriate cellular compartment to function. As with other types of therapeutics, delivery vehicles for nucleic acids must also be designed to avoid unwanted side effects; thus, the ability of such carriers to target their cargo to cancer cells is crucial. Classes of nucleic acids, hurdles that must be overcome for effective intracellular delivery, types of nonviral nanomaterials used as delivery vehicles, and the different strategies that can be employed to target nucleic acid delivery specifically to tumor cells are discussed. Additonally, nanoparticle designs that facilitate multiplexed delivery of combinations of nucleic acids are reviewed.

Synthesis and evaluation of antiproliferative microtubule-destabilising combretastatin A-4 piperazine conjugates

Microtubules are a validated clinical target for the treatment of many cancers. We describe the design, synthesis, biochemical evaluation, and molecular modelling studies of a series of analogues of the microtubule-destabilising agent, combretastatin A-4 (CA-4). Our series of 33 novel compounds contain the CA-4 core structure with modifications to the stilbene linking group, and are predominantly piperazine derivatives. Synthesis was achieved in a two-step process by firstly obtaining the acrylic acid via a Perkin reaction using microwave enhanced synthesis, followed by coupling using either DCC or Mukaiyama's reagent. All target compounds were screened for antiproliferative activity in MCF-7 breast cancer cells. Hydroxyl derivative (E)-3-(4-hydroxy-3-methoxyphenyl)-1-(4-phenylpiperazin-1-yl)-2-(3,4,5-trimethoxyphenyl) propenone (4m) displayed potent antiproliferative activity (IC50 = 190 nM). Two amino-containing derivatives, (E)-3-(3-amino-4-methoxyphenyl)-1-(4-phenylpiperazin-1-yl)-2-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (4q) and (E)-3-(3-amino-4-methoxyphenyl)-1-(4-(p-tolyl)piperazin-1-yl)-2-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (4x), were the most potent with IC50 values of 130 nM and 83 nM respectively. Representative compounds were shown to depolymerise tubulin, induce G2/M arrest and apoptosis in MCF-7 cells but not peripheral blood mononuclear cells, and induce cleavage of the DNA repair enzyme poly ADP ribose polymerase (PARP) in MCF-7 cells. Modelling studies predict that the compounds bind to tubulin within the colchicine-binding site. These compounds are a valuable addition to the library of CA-4 analogues and 4m, 4q and 4x will be developed further as novel, water-soluble molecules targeting microtubules.

Miki (Mitotic Kinetics Regulator) Immunoexpression in Normal Liver, Cirrhotic Areas and Hepatocellular Carcinomas: a Preliminary Study with Clinical Relevance

Hepatocellular carcinoma (HCC) is the most common type of primary malignant tumor in the liver. One of the main features of cancer survival is the generalized loss of growth control exhibited by cancer cells, and Miki is a protein related to the immunoglobulin superfamily that plays an important role in mitosis. We aim to study protein expression levels of Miki in non-tumoral liver and 20 HCCs recruited from a Pathology Department. Clinical information was also obtained. A tissue microarray was performed, and immunohistochemical techniques applied to study protein expression levels of Miki. In normal liver, Miki was weakly expressed, showing nuclear staining in the hepatocytes. Cirrhotic areas and HCCs showed a variety of staining patterns. Most HCC samples showed positive expression, with three different staining patterns being discernible: nuclear, cytoplasmic and mixed. Statistical analysis showed a significant association between grade of differentiation, Ki-67 proliferative index, survival rates and staining patterns. This study has revealed the positive expression of Miki in normal liver, cirrhotic areas and HCCs. Three different staining patterns of Miki expression with clinical relevance were noted in HCCs.

Cytological and genetic consequences for the progeny of a mitotic catastrophe provoked by Topoisomerase II deficiency

Topoisomerase II (Top2) removes topological linkages between replicated chromosomes. Top2 inhibition leads to mitotic catastrophe (MC) when cells unsuccessfully try to split their genetic material between the two daughter cells. Herein, we have characterized the fate of these daughter cells in the budding yeast. Clonogenic and microcolony experiments, in combination with vital and apoptotic stains, showed that 75% of daughter cells become senescent in the short term; they are unable to divide but remain alive. Decline in cell vitality then occurred, yet slowly, uncoordinatedly when comparing pairs of daughters, and independently of the cell death mediator Mca1/Yca1. Furthermore, we showed that senescence can be modulated by ploidy, suggesting that gross chromosome imbalances during segregation may account for this phenotype. Indeed, we found that diploid long-term survivors of the MC are prone to genomic imbalances such as trisomies, uniparental disomies and terminal loss of heterozygosity (LOH), the latter affecting the longest chromosome arms.

Antitumor and antioxidant effects of Clinacanthus nutans Lindau in 4 T1 tumor-bearing mice

Background

Clinacanthus nutans Lindau (C. nutans) is a species of in Acanthaceae family and primarily used in South East Asian countries. C. nutans is well known as Sabah snake grass in Malaysia, and its leaves have diverse medicinal potential in conventional applications, including cancer treatments. On the basis of literature search, there is less conclusive evidence of the involvement of phytochemical constituents in breast cancer, in particular, animal tumor models. The current study aimed to determine the antitumor and antioxidant activities of C. nutans extract in 4 T1 tumor-bearing mice.

Methods

C. nutans leaves were subjected to methanol extraction and divided into two different concentrations, 200 mg/kg (low-dose) and 1000 mg/kg (high-dose). The antitumor effects of C. nutans extracts were assessed using bone marrow smearing, clonogenic, and splenocyte immunotype analyses. In addition, hematoxylin and eosin, tumor weight and tumor volume profiles also used to indicate apoptosis appearance. Serum cytokine levels were examined using ELISA assay. In addition, nitric oxide assay reflecting antioxidant activity was performed.

Results

From the results obtained, the methanol extract of C. nutans leaves at 200 mg/kg (P < 0.05) and 1000 mg/kg (P < 0.05) showed a significant decrease in nitric oxide (NO) and malondialdehyde (MDA) levels in the blood. On the other hand, C. nutans extract (1000 mg/kg) also showed a significant decrease in the number of mitotic cells, tumor weight, and tumor volume. No inflammatory and adverse reactions related to splenocytes activities were found in all treated groups of mice. Despite its promising results, the concentration of both C. nutans extracts have also reduced the number of colonies formed in the liver and lungs.

Conclusion

In conclusion, C. nutans extracts exert antitumor and antioxidant activities against 4 T1 mouse breast model with no adverse effect and inflammatory response at high dose of 1000 mg/kg, indicating an effective and complementary approach for cancer prevention and treatment.

Deubiquitinating Enzymes: A Critical Regulator of Mitosis

Mitosis is a complex and dynamic process that is tightly regulated by a large number of mitotic proteins. Dysregulation of these proteins can generate daughter cells that exhibit genomic instability and aneuploidy, and such cells can transform into tumorigenic cells. Thus, it is important for faithful mitotic progression to regulate mitotic proteins at specific locations in the cells at a given time in each phase of mitosis. Ubiquitin-dependent modifications play critical roles in this process by regulating the degradation, translocation, or signal transduction of mitotic proteins. Here, we review how ubiquitination and deubiquitination regulate the progression of mitosis. In addition, we summarize the substrates and roles of some deubiquitinating enzymes (DUBs) crucial for mitosis and describe how they contribute error correction during mitosis and control the transition between the mitotic phases.

Photo-Uncaging of a Microtubule-Targeted Rigidin Analogue in Hypoxic Cancer Cells and in a Xenograft Mouse Model

Marine alkaloid rigidins are cytotoxic compounds known to kill cancer cells at nanomolar concentrations by targeting the microtubule network. Here, a rigidin analogue containing a thioether group was "caged" by coordination of its thioether group to a photosensitive ruthenium complex. In the dark, the coordinated ruthenium fragment prevented the rigidin analogue from inhibiting tubulin polymerization and reduced its toxicity in 2D cancer cell line monolayers, 3D lung cancer tumor spheroids (A549), and a lung cancer tumor xenograft (A549) in nude mice. Photochemical activation of the prodrug upon green light irradiation led to the photosubstitution of the thioether ligand by water, thereby releasing the free rigidin analogue capable of inhibiting the polymerization of tubulin. In cancer cells, such photorelease was accompanied by a drastic reduction of cell growth, not only when the cells were grown in normoxia (21% O2) but also remarkably in hypoxic conditions (1% O2). In vivo, low toxicity was observed at a dose of 1 mg·kg-1 when the compound was injected intraperitoneally, and light activation of the compound in the tumor led to 30% tumor volume reduction, which represents the first demonstration of the safety and efficacy of ruthenium-based photoactivated chemotherapy compounds in a tumor xenograft.

Identification of candidate molecular targets of the novel antineoplastic antimitotic NP-10

We previously reported the identification of a novel antimitotic agent with carbazole and benzohydrazide structures: N′-[(9-ethyl-9H-carbazol-3-yl)methylene]-2-iodobenzohydrazide (code number NP-10). However, the mechanism(s) underlying the cancer cell-selective inhibition of mitotic progression by NP-10 remains unclear. Here, we identified NP-10-interacting proteins by affinity purification from HeLa cell lysates using NP-10-immobilized beads followed by mass spectrometry. The results showed that several mitosis-associated factors specifically bind to active NP-10, but not to an inactive NP-10 derivative. Among them, NUP155 and importin β may be involved in NP-10-mediated mitotic arrest. Because NP-10 did not show antitumor activity in vivo in a previous study, we synthesized 19 NP-10 derivatives to identify more effective NP-10-related compounds. HMI83-2, an NP-10-related compound with a Cl moiety, inhibited HCT116 cell tumor formation in nude mice without significant loss of body weight, suggesting that HMI83-2 is a promising lead compound for the development of novel antimitotic agents.

Biophysical restriction of growth area using a monodispersed gold sphere nanobarrier prolongs the mitotic phase in HeLa cells

Gold nanoparticles are widely exploited for biological and biotechnical applications owing to their stability, biocompatibility, and known effects on cellular behaviors. Many studies have focused on nanoparticles that are internalized into cells, but extracellular nanoparticles also can regulate cell behavior, a practice known as in-plane surface nanotopography. We demonstrated that nanobarriers composed of morphologically homogeneous gold nanospheres prolonged the mitotic (M) phase in the cervical cancer cell line HeLa without inducing apoptosis. The nanobarrier was formed by electrostatic deposition of nanospheres on a negatively charged, fibronectin-coated substrate. We tested the effects of differently sized nanospheres. Gold nanospheres 42 nm in diameter were found to be non-toxic, while 111 nm nanospheres induced the production of reactive oxygen species, resulting in apoptotic cell death and arrest of cytokinesis. When exposed to sufficient 83 nm gold nanospheres to fabricate a surface nanobarrier, the M phase was delayed but cells proceeded to cytokinesis and the G1 phase. Live-cell imaging showed that the M phase increased by 2.9 h, 2.4 times longer than in control cells. Biophysical analyses indicated that this could be attributed to the specific size of the nanobarrier that physically limited the growth area around the cell.

Discovery of thalicthuberine as a novel antimitotic agent from nature that disrupts microtubule dynamics and induces apoptosis in prostate cancer cells

We report for the first time the mechanism of action of the natural product thalicthuberine (TH) in prostate and cervical cancer cells. TH induced a strong accumulation of LNCaP cells in mitosis, severe mitotic spindle defects, and asymmetric cell divisions, ultimately leading to mitotic catastrophe accompanied by cell death through apoptosis. However, unlike microtubule-binding drugs (vinblastine and paclitaxel), TH did not directly inhibit tubulin polymerization when tested in a cell-free system, whereas it reduced cellular microtubule polymer mass in LNCaP cells. This suggests that TH indirectly targets microtubule dynamics through inhibition of a critical regulator or tubulin-associated protein. Furthermore, TH is not a major substrate for P-glycoprotein (Pgp), which is responsible for multidrug resistance in numerous cancers, providing a rationale to further study TH in cancers with Pgp-mediated treatment resistance. The identification of TH's molecular target in future studies will be of great value to the development of TH as potential treatment of multidrug-resistant tumors.

Temozolomide and Other Alkylating Agents in Glioblastoma Therapy

The alkylating agent temozolomide (TMZ) together with maximal safe bulk resection and focal radiotherapy comprises the standard treatment for glioblastoma (GB), a particularly aggressive and lethal primary brain tumor. GB affects 3.2 in 100,000 people who have an average survival time of around 14 months after presentation. Several key aspects make GB a difficult to treat disease, primarily including the high resistance of tumor cells to cell death-inducing substances or radiation and the combination of the highly invasive nature of the malignancy, i.e., treatment must affect the whole brain, and the protection from drugs of the tumor bulk—or at least of the invading cells—by the blood brain barrier (BBB). TMZ crosses the BBB, but—unlike classic chemotherapeutics—does not induce DNA damage or misalignment of segregating chromosomes directly. It has been described as a DNA alkylating agent, which leads to base mismatches that initiate futile DNA repair cycles; eventually, DNA strand breaks, which in turn induces cell death. However, while much is assumed about the function of TMZ and its mode of action, primary data are actually scarce and often contradictory. To improve GB treatment further, we need to fully understand what TMZ does to the tumor cells and their microenvironment. This is of particular importance, as novel therapeutic approaches are almost always clinically assessed in the presence of standard treatment, i.e., in the presence of TMZ. Therefore, potential pharmacological interactions between TMZ and novel drugs might occur with unforeseeable consequences.

In vivo toxicity assays in zebrafish embryos: a pre-requisite for xenograft preclinical studies

The human cancer cell xenograft in zebrafish embryos has become a very useful preclinical tool in oncology research. While many anticancer drugs have been assayed with this model, few studies regarding the toxicity limits of these drugs for the host have been addressed. Here, we evaluated the acute toxicity of five approved and routinely used human anticancer drugs embracing different mechanism action types: Carboplatin (CarboPt), Irinotecan (IT), Doxorubicin (DOX), Paclitaxel (PT) and Chloroquine (CQ). They were tested in zebrafish embryos using the Fish Embryo Acute Toxicity (FET) test at 0 and 72 hours per fertilization (hpf). Additionally, we compared those results with in vitro toxicity assays and could find notable differences between both models. Our results indicate that the toxicity data of a compound evaluated in vitro and in a FET test at 0 hpf do not guarantee a reliable toxicity determination for performing xenografts in zebrafish, being necessary additional toxicity studies using 72 hpf embryos, the starting point of drug treatment in this kind of preclinical assays.

PLGA based particles as "drug reservoir" for antitumor drug delivery: characterization and cytotoxicity studies

Doxorubicin (DOX) is commonly used to treat several tumor types, but its severe side effects, primarily cardiotoxicity, represent a major limitation for its use in clinical settings. In this study we developed and characterized biodegradable and stable poly(D,L-lactic-co-glycolic) acid (PLGA) submicrocarriers employing an osmosis-based patented methodology, which allowed to optimize the drug loading efficiency up to 99%. Proceeding from this, we evaluated on MCF-7, a human breast cancer cell line, the ability of PLGA to promote the internalization of DOX and to improve its cytotoxicity in vitro. We found that the in vitro uptake efficiency is dramatically increased when DOX is loaded within PLGA colloidal carriers, which adhere to the cell membrane behaving as an efficient drug reservoir. In fact, the particles provide a diffusion-driven, sustained release of DOX across the cell membrane, resulting in high drug concentration. Accordingly, the cytotoxic analysis clearly showed that DOX-loaded PLGA exhibit a lower 50% inhibitory concentration than free DOX. The decay time of cell viability was successfully compared with DOX diffusion time constant from PLGA. The overall in vitro results highlight the potential of DOX-loaded PLGA particles to be employed as vectors with improved antitumor efficacy.

Investigation of natural phenanthrenes and the antiproliferative potential of juncusol in cervical cancer cell lines

BACKGROUND

Phenanthrenes isolated from Juncus species possess different biological activities, including antiproliferative and antimigratory effects.

PURPOSE

In this study, nine phenanthrenes isolated from the roots of Juncus inflexus were investigated for their antiproliferative activity on several gynecological cancer cell lines, using non-cancerous cells as controls.

METHODS

Antiproliferative activities of the compounds were determined by means of MTT assay. Flow cytometry was used for cell cycle analysis and determination of mitotic cells. Activities of caspase-3, -8, and -9 were detected by colorimetric kits. Tubulin polymerization was followed by kinetic absorbance determination. Action on tumor cell migration was described using wound healing assay. Western blot assays were used to determine apoptosis-related factors at protein level.

RESULTS

Among the compounds tested, juncusol exhibited the most substantial antiproliferative effect against cervical cancer HeLa cells. It was also revealed that juncusol has a distinct growth inhibitory effect in cervical cancer cell lines of various HPV status: it was highly active in HPV type 18-positive HeLa cells, while it was inactive in HPV type 16-positive SiHa and CaSki cells. Cell cycle analysis showed an increase in G2/M and subG1 cell populations after juncusol treatment. Caspase-3, -8, and -9 were detected to be activated by juncusol in HeLa cells, indicating that juncusol induces apoptotic cell death. Moreover, juncusol inhibited tubulin polymerization, as well as EGFR activation, suggesting two possible additional mechanisms that may account for juncusol's inducing a G2/M-phase cell cycle arrest and inhibiting cell migration.

CONCLUSION

These results suggest that juncusol is a potent antiproliferative agent against HPV-18 related cervical cancer and may be considered as a lead compound for the development of innovative anticancer agents.

Geraniin Differentially Modulates Chromosome Stability of Colon Cancer and Noncancerous Cells by Oppositely Regulating their Spindle Assembly Checkpoint

Geraniin has been reported to specifically induce apoptosis in multiple human cancers, but the underlying mechanism is poorly defined. The spindle assembly checkpoint (SAC) is a surveillance system to ensure high-fidelity chromosome segregation during mitosis. Weakening of SAC to enhance chromosome instability (CIN) can be therapeutic because very high levels of CIN are lethal. In this study, we have investigated the effects of geraniin on the SAC of colorectal cancer HCT116 cells and noncancerous colon epithelial CCD841 cells. We find that treatment of HCT116 cells with geraniin leads to dose-dependent decrease of cell proliferation, colony formation, and anchorage-independent growth. Geraniin is found to induce apoptosis in mitotic and postmitotic HCT116 cells. Furthermore, geraniin weakens the SAC function of HCT116 cells by decreasing the transcriptional expression of several SAC kinases (particularly Mad2 and Bub1), which in turn leads to premature anaphase entry, mitotic aberrations, and CIN in HCT116 cells. In contrast, the proliferation of CCD841 cells is slightly inhibited by geraniin. Even more interestingly, geraniin increases the transcriptional expression of several SAC kinases (e.g., Mad1 and BubR1) to strengthen SAC efficiency, which contributes to the reduction of mitotic aberrations and CIN in CCD841 cells. Altogether, our findings reveal that the SAC pathway in human colon cancer and noncancerous cell lineages responses oppositely to geraniin treatment, resulting CIN promotion and suppression, respectively. Specific abrogation of SAC to induce catastrophic CIN in HCT116 cells may account for the selective anticancer action of geraniin.. Environ. Mol. Mutagen. 60:254-268, 2019. © 2018 Wiley Periodicals, Inc.

Resistance to anti-microtubule drug-induced cell death is determined by regulation of BimEL expression

Anti-microtubule agents are frequently used as anticancer therapeutics. Cell death induced by these agents is considered to be due to sustained mitotic arrest caused by the activation of spindle assembly checkpoint (SAC). However, some cell types are resistant to mitotic cell death. Cells' ability to escape mitotic arrest (mitotic slippage) is thought to be a major mechanism contributing to this resistance. Here, we show that resistance to cell death induced by anti-mitotic agents is not linked to cells' capacity to undergo mitotic slippage as generally believed but is dependent on the state of BimEL regulation during mitosis. While transcriptional repression of BimEL in the mitotic death-resistant cells involves polycomb repressive complex 2 (PRC2)-mediated histone trimethylation, the BimEL protein is destabilized by cullin 1/4A-βTrCP-dependent degradation involving activation of cullin 1/4A by neddylation. These results imply that pharmacological augmentation of BimEL activity in anti-microtubule drug-resistant tumors may have important therapeutic implications.

GSK923295 as a potential antihepatocellular carcinoma agent causing delay on liver regeneration after partial hepatectomy

BACKGROUND

The clinical trials emerged centromere protein E inhibitor GSK923295 as a promising anticancer drug, but its function in hepatocellular carcinoma (HCC) remain needs to be fully elucidated, especially as chemotherapy after hepatectomy for liver tumors. We aimed to describe anti-HCC activities of GSK923295 and compare its antiproliferative effects on liver regeneration after partial hepatectomy (PH).

METHODS

All subjects were randomized to treatment with either vehicle or GSK923295. Antitumor activity of GSK923295 was assessed by xenograft growth assays. The C57BL/6 mice were subjected to 70% PH and the proliferation was calculated by liver coefficient, further confirmed by immunohistochemistry. The proliferation and cell cycle analysis of liver cell AML12 and HCC cells LM3, HUH7, and HepG2 were investigated using the cell counting kit-8 assay and Flow Cytometry. The chromosome misalignment and segregation in AML12 cells were visualized by immunofluorescence.

RESULTS

Treatment with GSK923295 induced antiproliferation in HCC cell lines. It also caused delay on HCC tumor growth instead of regression both in a HCC cell line xenograft model and patient-derived tumor xenograft model. With microarray analysis, CENtromere Protein E was gradually increased in mouse liver after PH. Exposure of liver cells to GSK923295 resulted in delay on a cell cycle in mitosis with a phenotype of misaligned chromosomes and chromosomes clustered. In 70% PH mouse model, GSK923295 treatment also remarkably reduced liver regeneration in later stage, in parallel with the mitotic marker phospho-histone H3 elevation.

CONCLUSION

The anticancer drug GSK923295 causes a significant delay on HCC tumor growth and liver regeneration after PH in later stage.

Mapping Mitotic Death: Functional Integration of Mitochondria, Spindle Assembly Checkpoint and Apoptosis

Targeting the mitotic pathways of rapidly proliferating tumor cells has been an effective strategy in traditional cancer therapy. Chemotherapeutics such as taxanes and vinca alkaloids, which disrupt microtubule function, have enjoyed clinical success; however, the accompanying side effects, toxicity and multi drug resistance remain as serious concerns. The emerging classes of inhibitors targeting mitotic kinases and proteasome face their own set of challenges. It is hoped that elucidation of the regulatory interface between mitotic checkpoints, mitochondria and mitotic death will aid the development of more efficacious anti-mitotic agents and improved treatment protocols. The links between the spindle assembly checkpoint (SAC) and mitochondrial dynamics that control the progression of anti-mitotic agent-induced apoptosis have been under investigation for several years and the functional integration of these various signaling networks is now beginning to emerge. In this review, we highlight current research on the regulation of SAC, the death pathway and mitochondria with particular focus on their regulatory interconnections.

Mitotic slippage: an old tale with a new twist

Targeting the mitotic machinery using anti-mitotic drugs for elimination of cancer cells is a century-old concept, which continues to be routinely used as a first line of treatment in the clinic. However, patient response remains unpredictable and drug resistance limits effectiveness of these drugs. Cancer cells exit from drug-induced mitotic arrest (mitotic slippage) to avoid subsequent cell death which is thought to be a major mechanism contributing to this resistance. The tumor cells that acquire resistance to anti-mitotic drugs have chromosomal instability (CIN) and are often aneuploid. In this review, we outline the key mechanisms involved in dictating the cell fate during perturbed mitosis and how these processes impede the efficacy of anti-mitotic therapies. Further, we emphasize the recent work from our laboratory, which highlights the functional role of CEP55 in protecting aneuploid cells from death. We also discuss the rationale of targeting CEP55 in vivo, which could prove to be a novel and effective therapeutic strategy for sensitizing cells to microtubule inhibitors and might offer significantly improved patient outcome. Abbreviations: APC/C: Anaphase-Promoting Complex/Cyclosome; BAD: BCL2-Associated agonist of cell Death; BAK1: BCL2 Antagonist Kinase1; BAX: BCL2-Associated X; BCL2: B-cell Chronic Lymphocytic Leukaemia (CLL)/Lymphoma 2; BH: BCL2 Homology Domain; BID: BH3-Interacting domain Death agonist; BIM: BCL2-Interacting Mediator of cell death; BUB: Budding Uninhibited by Benzimidazoles; CDC: Cell Division Cycle; CDH1: Cadherin-1; CDK1: Cyclin-Dependent Kinase 1; CEP55: Centrosomal Protein (55 KDa): CIN: Chromosomal Instability; CTA: Cancer Testis Antigen; EGR1: Early Growth Response protein 1; ERK: Extracellular Signal-Regulated Kinase; ESCRT: Endosomal Sorting Complexes Required for Transport; GIN: Genomic Instability; MAD2: Mitotic Arrest Deficient 2; MCL1: Myeloid Cell Leukemia sequence 1; MPS1: Monopolar Spindle 1 Kinase; MYT1: MYelin Transcription factor 1; PLK1: Polo Like Kinase 1; PUMA: p53-Upregulated Mediator of Apoptosis; SAC: Spindle Assembly Checkpoint; TAA: Tumor-Associated Antigen.

Synthesis and biological evaluation of N-biphenyl-nicotinic based moiety compounds: A new class of antimitotic agents for the treatment of Hodgkin Lymphoma

We previously demonstrated that some N-biphenylanilides caused cell-cycle arrest at G2/M transition in breast cancer cells. Among them we choose three derivatives, namely PTA34, PTA73 and RS35 for experimentation in solid tumor cell lines, classical Hodgkin Lymphoma (cHL) cell lines and bona fide normal cell lines. Almost all tumor cells were sensitive to compounds in the nanomolar range whereas, they were not cytotoxic to normal ones. Interestingly the compounds caused a strong G2/M phase arrest in cHL cell lines, thus, here we investigated whether they affected the integrity of microtubules in such cells. We found that they induced a long prometaphase arrest, followed by induction of apoptosis which involved mitochondria. PTA73 and RS35 induced the mitotic arrest through the fragmentation of microtubules which prevented the kinethocore-mitotic spindle interaction and the exit from mitosis. PTA34 is instead a tubulin-targeting agent because it inhibited the tubulin polymerization as vinblastine. As such, PTA34 maintained the Cyclin B1-CDK1 regulatory complex activated during the G2/M arrest while inducing the inactivation of Bcl-2 through phosphorylation in Ser70, the degradation of Mcl-1 and a strong activation of BIML and BIMS proapoptotic isoforms. In addition PTA34 exerted an antiangiogenic effect by suppressing microvascular formation.

Drug-free macromolecular therapeutics exhibit amplified apoptosis in G2/M phase arrested cells

Drug-free macromolecular therapeutics (DFMT) have been recently developed to treat non-Hodgkin lymphoma (NHL). It is a consecutive delivery of two nanoconjugates: (1) bispecific engager that pretargets surface CD20, and (2) multivalent effector polymer that hybridises with CD20-bound engagers. Without the need of low molecular weight drug, the hybridisation of morpholino oligonucleotide containing DFMT at NHL cell surface triggers CD20 crosslinking and subsequent apoptosis. We have previously determined various factors that affect the efficacy of DFMT regarding the synthetic structures. Here, we show that DFMT-mediated apoptosis is also influenced by the state of cells. Compared with other cell cycle states, cells arrested at G2/M phase exhibit enhanced CD20 expression, and have more sustainable CD20 binding by DFMT, resulting in a higher degree of DFMT-mediated CD20 crosslinking. Moreover, the anti-apoptotic Bcl-2 protein was phosphorylated in G2/M phase, thereby increasing the cell susceptibility to DFMT. As a result, DFMT mediated augmented apoptosis in G2/M phase cells. When DFMT was combined with a polymer-docetaxel conjugate that triggered G2/M blockage, a combinatorial apoptotic effect was achieved to induce programmed cell death. Our findings suggest the co-delivery of DFMT and G2/M inhibiting drug combinations may present a therapeutic advantage in NHL treatment.

Natural products as new antimitotic compounds for anticancer drug development

Cell cycle control genes are frequently mutated in cancer cells, which usually display higher rates of proliferation than normal cells. Dysregulated mitosis leads to genomic instability, which contributes to tumor progression and aggressiveness. Many drugs that disrupt mitosis have been studied because they induce cell cycle arrest and tumor cell death. These antitumor compounds are referred to as antimitotics. Vinca alkaloids and taxanes are natural products that target microtubules and inhibit mitosis, and their derivatives are among the most commonly used drugs in cancer therapy worldwide. However, severe adverse effects such as neuropathies are frequently observed during treatment with microtubule-targeting agents. Many efforts have been directed at developing improved antimitotics with increased specificity and decreased likelihood of inducing side effects. These new drugs generally target specific components of mitotic regulation that are mainly or exclusively expressed during cell division, such as kinases, motor proteins and multiprotein complexes. Such small molecules are now in preclinical studies and clinical trials, and many are products or derivatives from natural sources. In this review, we focused on the most promising targets for the development of antimitotics and discussed the advantages and disadvantages of these targets. We also highlighted the novel natural antimitotic agents under investigation by our research group, including combretastatins, withanolides and pterocarpans, which show the potential to circumvent the main issues in antimitotic therapy.

Zerumbone, a cyclic sesquiterpene, exerts antimitotic activity in HeLa cells through tubulin binding and exhibits synergistic activity with vinblastine and paclitaxel

Objectives

The aim of this study was to elucidate the antimitotic mechanism of zerumbone and to investigate its effect on the HeLa cells in combination with other mitotic blockers.

Materials and methods

HeLa cells and fluorescence microscopy were used to analyse the effect of zerumbone on cancer cell lines. Cellular internalization of zerumbone was investigated using FITC‐labelled zerumbone. The interaction of zerumbone with tubulin was characterized using fluorescence spectroscopy. The Chou and Talalay equation was used to calculate the combination index.

Results

Zerumbone selectively inhibited the proliferation of HeLa cells with an IC₅₀ of 14.2 ± 0.5 μmol/L through enhanced cellular uptake compared to the normal cell line L929. It induced a strong mitotic block with cells exhibiting bipolar spindles at the IC₅₀ and monopolar spindles at 30 μmol/L. Docking analysis indicated that tubulin is the principal target of zerumbone. In vitro studies indicated that it bound to goat brain tubulin with a Kd of 4 μmol/L and disrupted the assembly of tubulin into microtubules. Zerumbone and colchicine had partially overlapping binding site on tubulin. Zerumbone synergistically enhanced the anti‐proliferative activity of vinblastine and paclitaxel through augmented mitotic block.

Conclusion

Our data suggest that disruption of microtubule assembly dynamics is one of the mechanisms of the anti‐cancer activity of zerumbone and it can be used in combination therapy targeting cell division.

A biosensor-based approach reveals links between efflux pump expression and cell cycle regulation in pleiotropic drug resistance of yeast

Multidrug resistance is highly conserved in mammalian, fungal, and bacterial cells, is characterized by resistance to several unrelated xenobiotics, and poses significant challenges to managing infections and many cancers. Eukaryotes use a highly conserved set of drug efflux transporters that confer pleiotropic drug resistance (PDR). To interrogate the regulation of this critical process, here we developed a small molecule-responsive biosensor that couples transcriptional induction of PDR genes to growth rate in the yeast Saccharomyces cerevisiae Using diverse PDR inducers and the homozygous diploid deletion collection, we applied this biosensor system to genome-wide screens for potential PDR regulators. In addition to recapitulating the activity of previously known factors, these screens identified a series of genes involved in a variety of cellular processes with significant but previously uncharacterized roles in the modulation of yeast PDR. Genes identified as down-regulators of the PDR included those encoding the MAD family of proteins involved in the mitotic spindle assembly checkpoint (SAC) complex. Of note, we demonstrated that genetic disruptions of the mitotic spindle assembly checkpoint elevate expression of PDR-mediating efflux pumps in response to exposure to a variety of compounds that themselves have no known influence on the cell cycle. These results not only establish our biosensor system as a viable tool for investigating PDR in a high-throughput fashion, but also uncover critical control mechanisms governing the PDR response and a previously uncharacterized link between PDR and cell cycle regulation in yeast.

Tumour treating fields in a combinational therapeutic approach

The standard of care for patients with newly diagnosed Glioblastoma multiforme (GBM) has remained unchanged since 2005, with patients undergoing maximal surgical resection, followed by radiotherapy plus concomitant and maintenance Temozolomide. More recently, Tumour treating fields (TTFields) therapy has become FDA approved for adult recurrent and adult newly-diagnosed GBM following the EF-11 and EF-14 trials, respectively. TTFields is a non-invasive anticancer treatment which utilizes medium frequency alternating electric fields to target actively dividing cancerous cells. TTFields selectively targets cells within mitosis through interacting with key mitotic proteins to cause mitotic arrest and cell death. TTFields therapy presents itself as a candidate for the combinational therapy route due to the lack of overlapping toxicities associated with electric fields. Here we review current literature pertaining to TTFields in combination with alkylating agents, radiation, anti-angiogenics, mitotic inhibitors, immunotherapies, and also with novel agents. This review highlights the observed synergistic and additive effects of combining TTFields with various other therapies, as well highlighting the strategies relating to combinations with electric fields.

Lipid accumulation facilitates mitotic slippage-induced adaptation to anti-mitotic drug treatment

Aberrant lipid accumulation is a hallmark of cancer known to contribute to its aggressiveness and malignancy. Emerging studies have demonstrated context-dependent changes in lipid metabolism during chemotherapy. However, there is little known regarding the mechanisms linking lipid metabolism to chemotherapy-induced cell fates. Here, we describe lipid accumulation in cells following antimitotic drug treatment. Cells arrested in mitosis, as well as cells that escaped mitotic arrest and underwent mitotic slippage, showed elevated cytoplasmic lipid droplets. Interestingly, we found that TOFA, a lipid biosynthesis inhibitor that targets acetyl-CoA carboxylase (ACC) and blocks lipid accumulation, promoted early slippage, reduced cellular stress and enhanced survival of antimitotic-treated cells. Our work previously revealed that cells that survive after mitotic slippage can become senescent and confer pro-tumourigenic effects through paracrine signalling. Modulating lipid biosynthesis in cells post slippage by TOFA amplified their inflammatory secretion profiles and accelerated the development of tumourigenic behaviour, particularly cell migration and invasion, in a paracrine-dependent manner. In contrast to TOFA, inhibition of lipid accumulation by C75, a drug targeting fatty acid synthase (FASN), significantly reduced the production of pro-tumourigenic factors and associated phenotypic effects. This suggests that discrete lipid biosynthesis pathways could contribute differentially to the regulation of pro-tumourigenic inflammation. The divergent effects of TOFA and C75 may be attributed to the opposing regulation of Malonyl-CoA, an intermediate in fatty acid synthesis that serves as a mediator of fatty acid oxidation. Taken together, our data reveal a previously unappreciated role for lipid accumulation in the cellular adaptation to antimitotic drug treatment. Targeting lipid biosynthesis in cells post slippage may reprogramme its secretory profile such that it not only negates tumour-promoting effects, but may also promote anti-tumour inflammation for clearance of post-slippage senescent cells.

CEP55 is a determinant of cell fate during perturbed mitosis in breast cancer

The centrosomal protein, CEP55, is a key regulator of cytokinesis, and its overexpression is linked to genomic instability, a hallmark of cancer. However, the mechanism by which it mediates genomic instability remains elusive. Here, we showed that CEP55 overexpression/knockdown impacts survival of aneuploid cells. Loss of CEP55 sensitizes breast cancer cells to anti-mitotic agents through premature CDK1/cyclin B activation and CDK1 caspase-dependent mitotic cell death. Further, we showed that CEP55 is a downstream effector of the MEK1/2-MYC axis. Blocking MEK1/2-PLK1 signaling therefore reduced outgrowth of basal-like syngeneic and human breast tumors in in vivo models. In conclusion, high CEP55 levels dictate cell fate during perturbed mitosis. Forced mitotic cell death by blocking MEK1/2-PLK1 represents a potential therapeutic strategy for MYC-CEP55-dependent basal-like, triple-negative breast cancers.

Kunitz type protease inhibitor EgKI-1 from the canine tapeworm Echinococcus granulosus as a promising therapeutic against breast cancer

EgKI-1, a member of the Kunitz type protease inhibitor family, is highly expressed by the oncosphere of the canine tapeworm Echinococcus granulosus, the stage that is infectious to humans and ungulates, giving rise to a hydatid cyst localized to the liver and other organs. Larval protoscoleces, which develop within the hydatid cyst, have been shown to possess anti-cancer properties, although the precise molecules involved have not been identified. We show that recombinant EgKI-1 inhibits the growth and migration of a range of human cancers including breast, melanoma and cervical cancer cell lines in a dose-dependent manner in vitro without affecting normal cell growth. Furthermore, EgKI-1 treatment arrested the cancer cell growth by disrupting the cell cycle and induced apoptosis of cancer cells in vitro. An in vivo model of triple negative breast cancer (MDA-MB-231) in BALB/c nude mice showed significant tumor growth reduction in EgKI-1-treated mice compared with controls. These findings indicate that EgKI-1 shows promise for future development as an anti-cancer therapeutic.

Genetics and Expression Profile of the Tubulin Gene Superfamily in Breast Cancer Subtypes and Its Relation to Taxane Resistance

Taxanes are a class of chemotherapeutic agents that inhibit cell division by disrupting the mitotic spindle through the stabilization of microtubules. Most breast cancer (BC) tumors show resistance against taxanes partially due to alterations in tubulin genes. In this project we investigated tubulin isoforms in BC to explore any correlation between tubulin alterations and taxane resistance. Genetic alteration and expression profiling of 28 tubulin isoforms in 6714 BC tumor samples from 4205 BC cases were analyzed. Protein-protein, drug-protein and alterations neighbor genes in tubulin pathways were examined in the tumor samples. To study correlation between promoter activity and expression of the tubulin isoforms in BC, we analyzed the ChIP-seq enrichment of active promoter histone mark H3K4me3 and mRNA expression profile of MCF-7, ZR-75-30, SKBR-3 and MDA-MB-231 cell lines. Potential correlation between tubulin alterations and taxane resistance, were investigated by studying the expression profile of taxane-sensitive and resistant BC tumors also the MDA-MB-231 cells acquired resistance to paclitaxel. All genomic data were obtained from public databases. Results showed that TUBD1 and TUBB3 were the most frequently amplified and deleted tubulin genes in the BC tumors respectively. The interaction analysis showed physical interactions of α-, β- and γ-tubulin isoforms with each other. The most of FDA-approved tubulin inhibitor drugs including taxanes target only β-tubulins. The analysis also revealed sex tubulin-interacting neighbor proteins including ENCCT3, NEK2, PFDN2, PTP4A3, SDCCAG8 and TBCE which were altered in at least 20% of the tumors. Three of them are tubulin-specific chaperons responsible for tubulin protein folding. Expression of tubulin genes in BC cell lines were correlated with H3K4me3 enrichment on their promoter chromatin. Analyzing expression profile of BC tumors and tumor-adjacent normal breast tissues showed upregulation of TUBA1A, TUBA1C, TUBB and TUBB3 and downregulation of TUBB2A, TUBB2B, TUBB6, TUBB7P pseudogene, and TUBGCP2 in the tumor tissues compared to the normal breast tissues. Analyzing taxane-sensitive versus taxane-resistant tumors revealed that expression of TUBB3 and TUBB6 was significantly downregulated in the taxane-resistant tumors. Our results suggest that downregulation of tumor βIII- and βV-tubulins is correlated with taxane resistance in BC. Based on our results, we conclude that aberrant protein folding of tubulins due to mutation and/or dysfunction of tubulin-specific chaperons may be potential mechanisms of taxane resistance. Thus, we propose studying the molecular pathology of tubulin mutations and folding in BC and their impacts on taxane resistance.

Genetics and Expression Profile of the Tubulin Gene Superfamily in Breast Cancer Subtypes and Its Relation to Taxane Resistance

Taxanes are a class of chemotherapeutic agents that inhibit cell division by disrupting the mitotic spindle through the stabilization of microtubules. Most breast cancer (BC) tumors show resistance against taxanes partially due to alterations in tubulin genes. In this project we investigated tubulin isoforms in BC to explore any correlation between tubulin alterations and taxane resistance. Genetic alteration and expression profiling of 28 tubulin isoforms in 6714 BC tumor samples from 4205 BC cases were analyzed. Protein-protein, drug-protein and alterations neighbor genes in tubulin pathways were examined in the tumor samples. To study correlation between promoter activity and expression of the tubulin isoforms in BC, we analyzed the ChIP-seq enrichment of active promoter histone mark H3K4me3 and mRNA expression profile of MCF-7, ZR-75-30, SKBR-3 and MDA-MB-231 cell lines. Potential correlation between tubulin alterations and taxane resistance, were investigated by studying the expression profile of taxane-sensitive and resistant BC tumors also the MDA-MB-231 cells acquired resistance to paclitaxel. All genomic data were obtained from public databases. Results showed that TUBD1 and TUBB3 were the most frequently amplified and deleted tubulin genes in the BC tumors respectively. The interaction analysis showed physical interactions of α-, β- and γ-tubulin isoforms with each other. The most of FDA-approved tubulin inhibitor drugs including taxanes target only β-tubulins. The analysis also revealed sex tubulin-interacting neighbor proteins including ENCCT3, NEK2, PFDN2, PTP4A3, SDCCAG8 and TBCE which were altered in at least 20% of the tumors. Three of them are tubulin-specific chaperons responsible for tubulin protein folding. Expression of tubulin genes in BC cell lines were correlated with H3K4me3 enrichment on their promoter chromatin. Analyzing expression profile of BC tumors and tumor-adjacent normal breast tissues showed upregulation of TUBA1A, TUBA1C, TUBB and TUBB3 and downregulation of TUBB2A, TUBB2B, TUBB6, TUBB7P pseudogene, and TUBGCP2 in the tumor tissues compared to the normal breast tissues. Analyzing taxane-sensitive versus taxane-resistant tumors revealed that expression of TUBB3 and TUBB6 was significantly downregulated in the taxane-resistant tumors. Our results suggest that downregulation of tumor βIII- and βV-tubulins is correlated with taxane resistance in BC. Based on our results, we conclude that aberrant protein folding of tubulins due to mutation and/or dysfunction of tubulin-specific chaperons may be potential mechanisms of taxane resistance. Thus, we propose studying the molecular pathology of tubulin mutations and folding in BC and their impacts on taxane resistance.

Unraveling mitotic protein networks by 3D multiplexed epitope drug screening

Three-dimensional protein localization intricately determines the functional coordination of cellular processes. The complex spatial context of protein landscape has been assessed by multiplexed immunofluorescent staining or mass spectrometry, applied to 2D cell culture with limited physiological relevance or tissue sections. Here, we present 3D SPECS, an automated technology for 3D Spatial characterization of Protein Expression Changes by microscopic Screening. This workflow comprises iterative antibody staining, high-content 3D imaging, and machine learning for detection of mitoses. This is followed by mapping of spatial protein localization into a spherical, cellular coordinate system, a basis for model-based prediction of spatially resolved affinities of proteins. As a proof-of-concept, we mapped twelve epitopes in 3D-cultured spheroids and investigated the network effects of twelve mitotic cancer drugs. Our approach reveals novel insights into spindle fragility and chromatin stress, and predicts unknown interactions between proteins in specific mitotic pathways. 3D SPECS's ability to map potential drug targets by multiplexed immunofluorescence in 3D cell culture combined with our automated high-content assay will inspire future functional protein expression and drug assays.

Silencing non-SMC chromosome-associated polypeptide G inhibits proliferation and induces apoptosis in hepatocellular carcinoma cells

The present study was designed to investigate the significance of non-structural maintenance of chromosomes (non-SMC) chromosome-associated polypeptide G (NCAPG), a subunit of condensin complex I, in the development of hepatocellular carcinoma (HCC). NCAPG protein expression in human HCC and paracancerous hepatic tissues were examined using immunohistochemistry, and NCAPG mRNA expression in HCC cell lines were quantified using quantitative RT-PCR. Lentivirus-mediated RNA interference was used to silence NCAPG in HCC cells. Cell proliferation was monitored by MTT assay. Cell colony-forming capacity was measured by colony formation assay. Apoptosis was determined by flow cytometry. The results showed that increased protein expression of NCAPG was found in HCC tissues compared with the matched paracancerous hepatic tissues. At the mRNA level, increased expression of NCAPG was found in HCC cells as opposed to the normal hepatocytes. Silencing of NCAPG in BEL-7404 and SMMC-7721 cells led to decreased cell proliferation and increased apoptosis. These changes were associated with increased mRNA expressions of P53, P27, and Bad, but decreased mRNA expression of EGFR, Akt, survivin, and JNK. NCAPG might play an oncogenic role in the development of liver cancer. Further studies to clarify its role and underlying mechanisms in the development of liver cancer are warranted.

BMI1 Drives Metastasis of Prostate Cancer in Caucasian and African-American Men and Is A Potential Therapeutic Target: Hypothesis Tested in Race-specific Models

PURPOSE

Metastasis is the major cause of mortality in prostate cancer patients. Factors such as genetic makeup and race play critical role in the outcome of therapies. This study was conducted to investigate the relevance of BMI1 in metastatic prostate cancer disease in Caucasian and African-Americans.

EXPERIMENTAL DESIGN

We employed race-specific prostate cancer models, clinical specimens, clinical data mining, gene-microarray, transcription-reporter assay, chromatin-immunoprecipitation (ChIP), IHC, transgenic-(tgfl/fl) zebrafish, and mouse metastasis models.

RESULTS

BMI1 expression was observed to be elevated in metastatic tumors (lymph nodes, lungs, bones, liver) of Caucasian and African-American prostate cancer patients. The comparative analysis of stage III/IV tumors showed an increased BMI1 expression in African-Americans than Caucasians. TCGA and NIH/GEO clinical data corroborated to our findings. We show that BMI1 expression (i) positively correlates to metastatic (MYC, VEGF, cyclin D1) and (ii) negative correlates to tumor suppressor (INKF4A/p16, PTEN) levels in tumors. The correlation was prominent in African-American tumors. We show that BMI1 regulates the transcriptional activation of MYC, VEGF, INKF4A/p16, and PTEN. We show the effect of pharmacological inhibition of BMI1 on the metastatic genome and invasiveness of tumor cells. Next, we show the anti-metastatic efficacy of BMI1-inhibitor in transgenic zebrafish and mouse metastasis models. Docetaxel as monotherapy has poor outcome on the growth of metastatic tumors. BMI1 inhibitor as an adjuvant improved the taxane therapy in race-based in vitro and in vivo models.

CONCLUSIONS

BMI1, a major driver of metastasis, represents a promising therapeutic target for treating advanced prostate cancer in patients (including those belonging to high-risk group).

[Web-mediated follow-up and prognosis in lung cancer patients]

E-health is fashionable, but clinical evidence of its usefulness is rare and limited to reporting symptoms without specific analysis. The Chaos theory is applicable to the dynamics of the cancer and brings possibilities of use of its properties to develop useful, relevant and validated tools for cancer patients monitoring. The Chaos theory is applicable to the understanding of tumor dynamics due to interactions between tumor, host, endothelial and immune cells. Observability theory is one of its properties which suggests that the follow-up of the host (the patient via its symptoms and its weight) is a strong variable to evaluate the dynamics of the disease and its impact. Intensive follow-up and analysis of patients' symptoms to detect recurrences and clinical complications via a web-application (Moovcare^TM) demonstrated its interest in nearly 300 patients in 4 prospective studies including 1 pilot trial showing a benefit of 27% survival rate at 1 year, and a randomized phase 3 trial with a 26% 1-year survival improvement as compared to a conventional follow-up. Six other intensive follow-up studies show favorable results in oncology for a total of more than 2,000 randomized patients.

In vivo toxicity study of quatro stimuli nanocontainers in pregnant rats: Gestation, parturition and offspring evaluation

The aim of the present study was to investigate the impact of intravenous administration of newly fabricated nanocontainers (NCs) on the last third of pregnancy in rats. Fifteen pregnant 3-month-old Wistar rats were separated into 3 groups. On the 15th and 17th day of pregnancy all animals received an intravenous administration of 1 ml of 15 mg of NCs (Group A), 1 ml of 5 mg NCs (Group B) while Control group received 1 ml of 0.9% NaCl. On the 14th and 17th of pregnancy ultrasonography was performed and the parameters evaluated were the width of placenta, the length and width of the embryonic sac, the foetus length and the heart rate. On parturition the number of pups per dam was evaluated. Half of the pups were euthanised the day after parturition and their liver and kidney was histologically evaluated and for the rest of the pups the body growth curve was evaluated until the age of 14 week. At the end of the 14th week the remaining pups were euthanised and their liver and kidney was histologically evaluated. At weaning the dams were euthanised and their liver and kidney was histologically evaluated. Ultrasonography: Baseline measurements of the width of placenta, the length and width of embryonic sac, the foetus length and the heart rate on the 14th day of pregnancy, revealed no statistical significant differences between groups. Comparison of the same values on the 17th day of pregnancy after 2 intravenous administrations of NCs showed no statistical significant effect on the respective parameters. The administration of NCs had no impact on the mean number of pups per dam. Additionally, no impact of the NCs on the body weights of the pups was observed on the 1st day after parturition. Moreover, comparisons between groups, for both sexes showed no difference on growth rate. During the histological evaluation no inflammatory, degenerative or neoplastic lesions were observed as far as the newborn, adult offspring and dams were concerned. According to our results no toxic impact of the low and high doses of the NCs was observed on the parameters selected to be evaluated.

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Nanocontainers toxicity study.

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Toxicological study on pregnant rats, foetuses and offspring.

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Ultrasonographic evaluation.

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Histological evaluation.

Pre-clinical pharmacology and mechanism of action of SG3199, the pyrrolobenzodiazepine (PBD) dimer warhead component of antibody-drug conjugate (ADC) payload tesirine

Synthetic pyrrolobenzodiazepine (PBD) dimers, where two PBD monomers are linked through their aromatic A-ring phenolic C8-positions via a flexible propyldioxy tether, are highly efficient DNA minor groove cross-linking agents with potent cytotoxicity. PBD dimer SG3199 is the released warhead component of the antibody-drug conjugate (ADC) payload tesirine (SG3249), currently being evaluated in several ADC clinical trials. SG3199 was potently cytotoxic against a panel of human solid tumour and haematological cancer cell lines with a mean GI₅₀ of 151.5 pM. Cells defective in DNA repair protein ERCC1 or homologous recombination repair showed increased sensitivity to SG3199 and the drug was only moderately susceptible to multidrug resistance mechanisms. SG3199 was highly efficient at producing DNA interstrand cross-links in naked linear plasmid DNA and dose-dependent cross-linking was observed in cells. Cross-links formed rapidly in cells and persisted over 36 hours. Following intravenous (iv) administration to rats SG3199 showed a very rapid clearance with a half life as short as 8 minutes. These combined properties of cytotoxic potency, rapid formation and persistence of DNA interstrand cross-links and very short half-life contribute to the emerging success of SG3199 as a warhead in clinical stage ADCs.

MASTL inhibition promotes mitotic catastrophe through PP2A activation to inhibit cancer growth and radioresistance in breast cancer cells

BACKGROUND

Although MASTL (microtubule-associated serine/threonine kinase-like) is a key mitotic kinase that regulates mitotic progression through the inactivation of tumor suppressor protein phosphatase 2A (PP2A), the antitumor mechanism of MASTL targeting in cancer cells is still unclear.

METHODS

MASTL expression was evaluated by using breast cancer tissue microarrays and public cancer databases. The effects of MASTL depletion with siRNAs were evaluated in various breast cancer cells or normal cells. Various methods, including cell viability, cell cycle, soft agar, immunoblotting, immunofluorescence, PP2A activity, live image, and sphere forming assay, were used in this study.

RESULTS

This study showed the oncosuppressive mechanism of MASTL targeting that promotes mitotic catastrophe through PP2A activation selectively in breast cancer cells. MASTL expression was closely associated with tumor progression and poor prognosis in breast cancer. The depletion of MASTL reduced the oncogenic properties of breast cancer cells with high MASTL expression, but did not affect the viability of non-transformed normal cells with low MASTL expression. With regard to the underlying mechanism, we found that MASTL inhibition caused mitotic catastrophe through PP2A activation in breast cancer cells. Furthermore, MASTL depletion enhanced the radiosensitivity of breast cancer cells with increased PP2A activity. Notably, MASTL depletion dramatically reduced the formation of radioresistant breast cancer stem cells in response to irradiation.

CONCLUSION

Our data suggested that MASTL inhibition promoted mitotic catastrophe through PP2A activation, which led to the inhibition of cancer cell growth and a reversal of radioresistance in breast cancer cells.