Natural-Product-Inspired Discovery of Trimethoxyphenyl-1,2,4-triazolosulfonamides as Potent Tubulin Polymerization Inhibitors

An approach of natural product-inspired strategy and incorporation of an NP-privileged motif has been investigated for the discovery of new tubulin polymerization inhibitors. Two series, N-Arylsulfonyl-3-arylamino-5-amino-1,2,4-triazole derivatives, and their isomers were considered. The compounds were synthesized by construction of the N-aryl-1,2,4-triazole-3,5-diamine motif and sulfonylation. Although the chemo- and regioselectivity in sulfonylation were challenging due to multiple ring-tautomerizable-NH and exocyclic NH2 functionalities present in the molecular motifs, the developed synthetic method enabled the preparation of designed molecular skeletons with biologically important motifs. The approach also led to explore interesting molecular regio- and stereochemical aspects valuable for activity. The X-ray crystallography study indicated that the hydrogen bonding between the arylamine-NH and the arylsulfonyl-"O" unit and appropriate molecular-functionality topology allowed the cis-locking of two aryls, which is important for tubulin-binding and antiproliferative properties. All synthesized compounds majorly showed characteristic antiproliferative effects in breast cancer cells (MCF-7), and four compounds exhibited potent antiproliferative activity. One compound potently bound to tubulin at the colchicine site and inhibited tubulin polymerization in vitro. The compound significantly depolymerized microtubules in MCF-7 cells, arrested the cells at the G2/M phase, and induced cell death. This study represents the importance of the design strategy in medicinal chemistry and the molecular structural features relevant to anticancer anti-tubulin properties. The explored molecules have the potential for further development.

Clitocybe nebularis extract and 5‑fluorouracil synergistically inhibit the growth of HT-29 colorectal cancer cells by inducing the S phase arrest

Although 5-fluorouracil (5-FU) is an important anticancer agent for the treatment of colorectal cancer, drug resistance, and dose-related side effects limit the effectiveness of the treatment. Therefore, developing new pharmaceuticals with effective and low toxicity is critically necessary for cancer therapy. This study aimed to investigate the cytotoxic activity of the Clitocybe nebularis mushroom extract (CN) on HT-29 human colon cancer cells. A series of in vitro experiments were performed on the HT-29, Caco-2, and HEK-293 cells, which includes cytotoxicity, drug interaction, colony formation, cell cycle, and migration assays. In addition, qRT-PCR experiment was also performed to investigate the potential molecular mechanisms of action of CN on the proliferation of colon cancer cell line. Our results show that CN exhibited selective cytotoxic activity on HT-29 and Caco-2 colon cancer cells, whereas no cytotoxic effect was observed on normal HEK-293 cells. With the combination of CN and 5‑FU, their cytotoxic activity on HT-29 cells was significantly increased compared to their use alone. In addition, the combination of CN and 5-FU also showed synergistic anticancer activity through cell cycle arrest in the S phase. The results also show that p21, p27, and p53 expression levels increased as a result of CN treatment. Our in vitro findings show that CN has a synergistic effect with 5-FU by inhibiting cell proliferation of colon cancer cells and inducing cell cycle arrest in the S phase.

Anticancer activity of D-LAK-120A, an antimicrobial peptide, in non-small cell lung cancer (NSCLC)

Non-small cell lung cancer (NSCLC) is a major cause of global cancer mortalities and accounts for approximately 80-85% of reported lung cancer cases. Conventional chemotherapeutics show limited application because of poor tumor selectivity and acquired drug resistance. Antimicrobial peptides (AMPs) have gained much attention as potential anticancer therapeutics owing to their high potency and high target selectivity and specificity with limited scope for drug resistance. In this study, D-LAK (D-LAK-120A), a cationic AMP, was evaluated for its anticancer efficacy in various NSCLC cell lines. D-LAK peptide demonstrated enhanced cytotoxicity in A549, H358, H1975, and HCC827 cell lines with inhibitory concentrations between 4.0 and 5.5 μM. An increase in the lactate dehydrogenase (LDH) levels and propidium iodide (PI) uptake across compromised membrane suggested membranolytic activity as an inhibition pathway. In addition, we found D-LAK induced lung cancer cell apoptosis and arrested cells in the S phase (DNA synthesis) of cell cycle. Moreover, a decreased mitochondrial membrane potential and elevated ROS levels were observed after D-LAK treatment, suggesting induction of mitochondria-mediated apoptosis. Additionally, D-LAK inhibited single cell proliferation and cancer cell migration in vitro. The tumor reduction observed in the 3D spheroid assay further suggests the potential use of D-LAK as an anticancer agent for NSCLC treatment. Our results postulate innovative insights on the anticancer mechanism of D-LAK, which may contribute to its further development into preclinical studies and a potential therapeutic.

Free radical biology in neurological manifestations: mechanisms to therapeutics interventions

Recent advancements and growing attention about free radicals (ROS) and redox signaling enable the scientific fraternity to consider their involvement in the pathophysiology of inflammatory diseases, metabolic disorders, and neurological defects. Free radicals increase the concentration of reactive oxygen and nitrogen species in the biological system through different endogenous sources and thus increased the overall oxidative stress. An increase in oxidative stress causes cell death through different signaling mechanisms such as mitochondrial impairment, cell-cycle arrest, DNA damage response, inflammation, negative regulation of protein, and lipid peroxidation. Thus, an appropriate balance between free radicals and antioxidants becomes crucial to maintain physiological function. Since the 1brain requires high oxygen for its functioning, it is highly vulnerable to free radical generation and enhanced ROS in the brain adversely affects axonal regeneration and synaptic plasticity, which results in neuronal cell death. In addition, increased ROS in the brain alters various signaling pathways such as apoptosis, autophagy, inflammation and microglial activation, DNA damage response, and cell-cycle arrest, leading to memory and learning defects. Mounting evidence suggests the potential involvement of micro-RNAs, circular-RNAs, natural and dietary compounds, synthetic inhibitors, and heat-shock proteins as therapeutic agents to combat neurological diseases. Herein, we explain the mechanism of free radical generation and its role in mitochondrial, protein, and lipid peroxidation biology. Further, we discuss the negative role of free radicals in synaptic plasticity and axonal regeneration through the modulation of various signaling molecules and also in the involvement of free radicals in various neurological diseases and their potential therapeutic approaches. The primary cause of free radical generation is drug overdosing, industrial air pollution, toxic heavy metals, ionizing radiation, smoking, alcohol, pesticides, and ultraviolet radiation. Excessive generation of free radicals inside the cell R1Q1 increases reactive oxygen and nitrogen species, which causes oxidative damage. An increase in oxidative damage alters different cellular pathways and processes such as mitochondrial impairment, DNA damage response, cell cycle arrest, and inflammatory response, leading to pathogenesis and progression of neurodegenerative disease other neurological defects.

Stachydrine hydrochloride inhibits hepatocellular carcinoma progression via LIF/AMPK axis

BACKGROUND

Hepatocellular carcinoma (HCC) is not only one of the four highest malignancies, but also the principal reason of cancer-related death worldwide, yet no effective medication for anti-HCC is available. Stachydrine hydrochloride (SH), an alkaloid component in Panzeria alaschanica Kupr, exhibits potent antitumor activity in breast cancer. However, the anti-HCC effects of SH remain unknown.

PURPOSE

Our study assessed the therapeutic effect of SH on HCC and tried to clarify the mechanisms by which it ameliorates HCC. No studies involving using SH for anti-HCC activity and molecular mechanism have been reported yet.

STUDY DESIGN/METHODS

We examined the cell viability of SH on HCC cells by MTT assay. The effect of SH on cell autophagy in HCC cells was verified by Western blot and Immunofluorescence test. Flow cytometry was performed to assess cell-cycle arrest effects. Cell senescence was detected using β-Gal staining and Western blot, respectively. An inhibitor or siRNA of autophagy, i.e., CQ and si LC-3B, were applied to confirm the role of autophagy acted in the anti-cancer function of SH. Protein expression in signaling pathways was detected by Western blot. Besides, molecular docking combined with cellular thermal shift assay (CETSA) was used for analysis. Patient-derived xenograft (PDX) model were built to explore the inhibitory effect of SH in HCC in vivo.

RESULTS

In vitro studies showed that SH possessed an anti-HCC effect by inducing autophagy, cell-cycle arrest and promoting cell senescence. Specifically, SH induced autophagy with p62 and LC-3B expression. Flow cytometry analysis revealed that SH caused an obvious cell-cycle arrest, accompanied by the decrease and increase in Cyclin D1 and p27 levels, respectively. Additionally, SH induced cell senescence with the induction of p21 in HCC cell lines. Mechanistically, SH treatment down-regulated the LIF and up-regulated p-AMPK. Moreover, PDX model in NSG mice was conducted to support the results in vitro.

CONCLUSION

This study is the first to report the inhibitory function of SH in HCC, which may be due to the induction of autophagy and senescence. This study provides novel insights into the anti-HCC efficacy of SH and it might be a potential lead compound for further development of drug candidates for HCC.

Novel thiazolidine derivatives as potent selective pro-apoptotic agents

A series of 2-arylthiazolidine-4-carboxylic acid amide derivatives were synthesized and their cytotoxic activity against three cancer cell lines (PC-3, SKOV3 and MDA-MB231) was evaluated. Various structural modifications were tried including modifications of the length of the amide chain and modifications of the 2-aryl part using disubstituted phenyl and thiophene derivatives. The structure activity relationship was evaluated based on the in vitro biological evaluation against the above mentioned three cancer cell lines. The most selective compounds towards cancer cells were further evaluated against DLD-1, NCI-H520, Du145, MCF-7 and NCI-N87 cancer cells. The dodecyl amide having the 4-bromothienyl as the 2-aryl, compound 2e, exhibited the highest selectivity for cancer cells vs non-tumor cells. Mechanistic studies of the anticancer effect of compound 2e in prostate cancer PC-3 and colorectal cancer DLD-1 cells revealed that 2e could prevent the cell cycle in the G0/G1 phase by up-regulating the expression of p21 and reducing the expression of CDK2 and cyclin E. It increased the pro-apoptotic protein Bax and cleaved caspase 3, and down-regulated the expression of anti-apoptotic protein Bcl-2 to induce apoptosis. In addition, 2e also downregulated AKT, N-cadherin, and vimentin proteins expression giving indication that 2e inhibit the PI3K/AKT pathway to regulate cell cycle arrest and induce apoptosis, and can regulate the expression of epithelial-mesenchymal transition-related proteins.

Epigenetic modulation and understanding of HDAC inhibitors in cancer therapy

The role of genetic and epigenetic factors in tumor initiation and progression is well documented. Histone deacetylases (HDACs), histone methyl transferases (HMTs), and DNA methyl transferases. (DNMTs) are the main proteins that are involved in regulating the chromatin conformation. Among these, histone deacetylases (HDAC) deacetylate the histone and induce gene repression thereby leading to cancer. In contrast, histone acetyl transferases (HATs) that include GCN5, p300/CBP, PCAF, Tip 60 acetylate the histones. HDAC inhibitors are potent drug molecules that can induce acetylation of histones at lysine residues and induce open chromatin conformation at tumor suppressor gene loci and thus resulting in tumor suppression. The key processes regulated by HDAC inhibitors include cell-cycle arrest, chemo-sensitization, apoptosis induction, upregulation of tumor suppressors. Even though FDA approved drugs are confined mainly to haematological malignancies, the research on HDAC inhibitors in glioblastoma multiforme and triple negative breast cancer (TNBC) are providing positive results. Thus, several combinations of HDAC inhibitors along with DNA methyl transferase inhibitors and histone methyl transferase inhibitors are in clinical trials. This review focuses on how HDAC inhibitors regulate the expression of coding and non-coding genes with specific emphasis on their anti-cancer potential.

Endothelial sprouting, proliferation, or senescence: tipping the balance from physiology to pathology

Therapeutic modulation of vascular cell proliferation and migration is essential for the effective inhibition of angiogenesis in cancer or its induction in cardiovascular disease. The general view is that an increase in vascular growth factor levels or mitogenic stimulation is beneficial for angiogenesis, since it leads to an increase in both endothelial proliferation and sprouting. However, several recent studies showed that an increase in mitogenic stimuli can also lead to the arrest of angiogenesis. This is due to the existence of intrinsic signaling feedback loops and cell cycle checkpoints that work in synchrony to maintain a balance between endothelial proliferation and sprouting. This balance is tightly and effectively regulated during tissue growth and is often deregulated or impaired in disease. Most therapeutic strategies used so far to promote vascular growth simply increase mitogenic stimuli, without taking into account its deleterious effects on this balance and on vascular cells. Here, we review the main findings on the mechanisms controlling physiological vascular sprouting, proliferation, and senescence and how those mechanisms are often deregulated in acquired or congenital cardiovascular disease leading to a diverse range of pathologies. We also discuss alternative approaches to increase the effectiveness of pro-angiogenic therapies in cardiovascular regenerative medicine.

Low-concentration staurosporine improves recombinant antibody productivity in Chinese hamster ovary cells without inducing cell death

Chinese hamster ovary (CHO) cells are used as host cells for biopharmaceutical production, including monoclonal antibodies (mAbs). Arresting the cell cycle with chemical compounds is an effective approach to improve biopharmaceutical productivity. In a previous study, potential new cell cycle-arresting compounds were screened from marine-derived microorganism culture extracts, and it was suggested that staurosporine might improve mAb productivity in CHO cells via cell cycle arrest. The purpose of this study was to demonstrate the effectiveness of staurosporine as a cell-cycle arresting compound to improve mAb productivity. The optimal staurosporine concentration range was initially investigated using batch cultures. Thereafter, the effects on the culture profile and mAb productivity were evaluated using fed-batch cultures. Staurosporine at concentrations ≥10 nM induced cell death, but at concentrations ≤5 nM did not. In the range of 2-4 nM, cell growth was inhibited, whereas the specific production rate (Qp) and cell longevity were improved in a dose-dependent manner. The Qp and maximum mAb concentration with 4 nM staurosporine improved by 36.3 and 5.2%, respectively, compared to those with control conditions. Cell viability post-culture without staurosporine was 40.0 ± 0.3%, whereas with 4 nM staurosporine, it was 90.1 ± 1.0%. Flow cytometric analysis indicated cell-cycle arrest at the G1/G0 phase with 4 nM staurosporine addition. The present study highlighted the efficacy of staurosporine in improving mAb production by causing cell-cycle arrest. Further research into staurosporine analogs and how to use them will lead to development of more effective industrial production technologies of biopharmaceuticals.

Elucidating the role of an immunomodulatory protein in cancer: From protein expression to functional characterization

Several fundamental discoveries made over the last two decades, in the field of cancer biology, have increased our understanding of the complex tumor micro- and macroenvironments. This has shifted the current empirical cancer therapies to more rationalized treatments targeting immunomodulatory proteins. From the point of identification, a protein target undergoes several interrogations, which are necessary to truly define its druggability. Here, we outline some basic steps that can be followed for in vitro characterization of a potential immunomodulatory protein target. We describe procedures for recombinant protein expression and purification including key annotations on protein cloning, expression systems, purification strategies and protein characterization using structural and biochemical approaches. For functional characterization, we provide detailed protocols for using flow-cytometric techniques in cell lines or primary cells to study protein expression profiles, proliferation, apoptosis and cell-cycle changes. This multilevel approach can provide valuable, in-depth understanding of any protein target with potential immunomodulatory effects.

Validation of NEDD8-conjugating enzyme UBC12 as a new therapeutic target in lung cancer

Background

The neddylation pathway is overactivated in human cancers. Inhibition of neddylation pathway has emerged as an attractive anticancer strategy. The mechanisms underlying neddylation overactivation in cancer remain elusive. MLN4924/Pevonedistat, a first-in-class NEDD8-activating enzyme (NAE, E1) inhibitor, exerts significant anti-tumor effects, but its mutagenic resistance remains unresolved.

Methods

The expression of NEDD8-conjugating enzyme UBC12/UBE2M (E2) and NEDD8 were estimated by bioinformatics analysis and western blot in human lung cancer cell lines. The malignant phenotypes of lung cancer cells were evaluated both in vitro and in vivo upon UBC12 knockdown. Cell-cycle arrest was evaluated by quantitative proteomic analysis and propidium iodide stain and fluorescence - activated cell sorting (FACS). The growth of MLN4924 - resistant H1299 cells was also evaluated upon UBC12 knockdown.

Findings

The mRNA level of UBC12 in lung cancer tissues was much higher than that in normal lung tissues, increased with disease deterioration, and positively correlated with NEDD8 expression. Moreover, the overexpression of UBC12 significantly enhanced protein neddylation modification whereas the downregulation of UBC12 reduced neddylation modification of target proteins. Functionally, neddylation inactivation by UBC12 knockdown suppressed the malignant phenotypes of lung cancer cells both in vitro and in vivo. The quantitative proteomic analysis and cell cycle profiling showed that UBC12 knockdown disturbed cell cycle progression by triggering G₂ phase cell-cycle arrest. Further mechanistical studies revealed that UBC12 knockdown inhibited Cullin neddylation, led to the inactivation of CRL E3 ligases and induced the accumulation of tumor-suppressive CRL substrates (p21, p27 and Wee1) to induce cell cycle arrest and suppress the malignant phenotypes of lung cancer cells. Finally, UBC12 knockdown effectively inhibited the growth of MLN4924-resistant lung cancer cells.

Interpretation

These findings highlight a crucial role of UBC12 in fine-tuned regulation of neddylation activation status and validate UBC12 as an attractive alternative anticancer target against neddylation pathway.

Fund

Chinese Minister of Science and Technology grant (2016YFA0501800), National Natural Science Foundation of China (Grant Nos. 81401893, 81625018, 81820108022, 81772470, 81572340 and 81602072), Innovation Program of Shanghai Municipal Education Commission (2019-01-07-00-10-E00056), Program of Shanghai Academic/Technology Research Leader (18XD1403800), National Thirteenth Five-Year Science and Technology Major Special Project for New Drug and Development (2017ZX09304001). The funders had no role in study design, data collection, data analysis, interpretation, writing of the report.

Cryptotanshinone has curative dual anti-proliferative and immunotherapeutic effects on mouse Lewis lung carcinoma

Lung cancer is currently the leading cause of cancer-related mortality with very limited effective therapy. Screening of a variety of traditional Chinese medicines (TCMs) for their capacity to inhibit the proliferation of human lung cancer A549 cells and to induce the in vitro maturation of human DCs led to the identification of cryptotanshinone (CT), a compound purified from the TCM Salvia miltiorrhiza Bunge. Here, CT was shown to inhibit the proliferation of mouse Lewis lung carcinoma (LLC) cells by upregulating p53, downregulating cyclin B1 and Cdc2, and, consequently, inducing G2/M cell-cycle arrest of LLC cells. In addition, CT promoted maturation of mouse and human DCs with upregulation of costimulatory and MHC molecules and stimulated DCs to produce TNFα, IL-1β, and IL-12p70, but not IL-10 in vitro. CT-induced maturation of DCs depended on MyD88 and also involved the activation of NF-κB, p38, and JNK. CT was effective in the treatment of LLC tumors and, when used in combination with low doses of anti-PD-L1, cured LLC-bearing mice with the induction of subsequent anti-LLC long-term specific immunity. CT treatment promoted T-cell infiltration and elevated the expression of genes typical of Th1 polarization in LLC tumor tissue. The therapeutic effect of CT and low doses of anti-PD-L1 was reduced by depletion of CD4 and CD8 T cells. This paper provides the first report that CT induces immunological antitumor activities and may provide a new promising antitumor immunotherapeutic.

Nuclear co-expression of p21 and p27 induced effective cell-cycle arrest in T24 cells treated with BCG

A proposed mechanism underlying the effect of bacillus Calmette-Guérin (BCG) treatment for bladder cancer cells is as follows: BCG-induced crosslinking of cell-surface receptors results in the activation of signaling cascades, including cell-cycle regulators. However, the clinical significance of cell-cycle regulators such as p21 and p27 is controversial. Here we investigated the relationship between BCG exposure and p21 and p27. We used confocal laser microscopy to examine the expression levels of pKi67, p21 and p27 in T24 cells (derived from human urothelial carcinoma) exposed six times to BCG. We performed dual immunofluorescence staining methods for p21 and p27 and observed the localization of nuclear and cytoplasm expressions. We investigated the priority of p27 over p21 regarding nuclear expression by using p27 Stealth RNAi™ (p27-siRNA). With 2-h BCG exposure, the nuclear-expression level of p21 and p27 was highest, while pKi67 was lowest. The percentage of double nuclear-expression of p21 and p27 in BCG cells was significantly higher than that in control cells during the 1st to 6th exposure (P < 0.05), and the expression of pKi67 showed the opposite of this pattern. Approximately 10% of the nuclear p21 was independent of p27, whereas the cytoplasmic p21 was dependent on p27. Our results suggested that the nuclear co-expression of p21 and p27 caused effective cell-cycle arrest, and thus the evaluation of the nuclear co-expression of p21 and p27 might help determine the effectiveness of BCG treatment.

Facile construction of fused benzimidazole-isoquinolinones that induce cell-cycle arrest and apoptosis in colorectal cancer cells

Colorectal cancer (CRC) is one of the most frequent, malignant gastrointestinal tumors, and strategies and effectiveness of current therapy are limited. A series of benzimidazole-isoquinolinone derivatives (BIDs) was synthesized and screened to identify novel scaffolds for CRC. Of the compounds evaluated, 7g exhibited the most promising anti-cancer properties. Employing two CRC cell lines, SW620 and HT29, 7g was found to suppress growth and proliferation of the cell lines at a concentration of ∼20 µM. Treatment followed an increase in G₂/M cell cycle arrest, which was attributed to cyclin B1 and cyclin-dependent kinase 1 (CDK1) signaling deficiencies with simultaneous enhancement in p21 and p53 activity. In addition, mitochondrial-mediated apoptosis was induced in CRC cells. Interestingly, 7g decreased phosphorylated AKT, mTOR and 4E-BP1 levels, while promoting the expression/stability of PTEN. Since PTEN controls input into the PI3K/AKT/mTOR pathway, antiproliferative effects can be attributed to PTEN-mediated tumor suppression. Collectively, these results suggest that BIDs exert antitumor activity in CRC by impairing PI3K/AKT/mTOR signaling. Against a small kinase panel, 7g exhibited low affinity at 5 µM suggesting anticancer properties likely stem through a non-kinase mechanism. Because of the novelty of BIDs, the structure can serve as a lead scaffold to design new CRC therapies.

Disulfide-masked iron prochelators: Effects on cell death, proliferation, and hemoglobin production

The iron metabolism of malignant cells, which is altered to ensure higher acquisition and utilization, motivates the investigation of iron chelation strategies in cancer treatment. In a prochelation approach aimed at increasing intracellular specificity, disulfide reduction/activation switches are incorporated on iron-binding scaffolds resulting in intracellularly activated scavengers. Herein, this strategy is applied to several tridentate donor sets including thiosemicarbazones, aroylhydrazones and semicarbazones. The novel prochelator systems are antiproliferative in breast adenocarcinoma cell lines (MCF-7 and metastatic MDA-MB-231) and do not result in the intracellular generation of oxidative stress. Consistent with iron deprivation, the tested prochelators lead to cell-cycle arrest at the G1/S interface and induction of apoptosis. Notably, although hemoglobin-synthesizing blood cells have the highest iron need in the human body, no significant impact on hemoglobin production was observed in the MEL (murine erythroleukemia) model of differentiating erythroid cells. This study provides new information on the intracellular effects of disulfide-based prochelators and indicates aroylhydrazone (AH1-S)2 as a promising prototype of a new class of antiproliferative prochelator systems.

Discovery of a highly active anticancer analogue of cardamonin that acts as an inducer of caspase-dependent apoptosis and modulator of the mTOR pathway

Cardamonin is a natural chalcone that has been shown to exhibit high anticancer activity. In an attempt to discover analogues of cardamonin with enhanced anticancer activity, 19 analogues were synthesized and tested against A549 and HK1 cell lines. Results of the MTS cell viability assay showed that several derivatives possessed cytotoxic activities that were several-fold more potent than cardamonin. SAR analysis showed the importance of the ketone and alkene groups for bioactivity, while substituting cardamonin's phenolic groups with more polar moieties resulted in activity enhancement. As part of the SAR study and further exploration of chemical space, the effect of metal coordination on cytotoxicity was also investigated, but it was only possible to successfully obtain the Cu (II) complex of cardamonin (19). Compound 19 was the most active analogue possessing IC₅₀ values of 13.2μM and 0.7μM against A549 and HK1 cells, corresponding to a 5- and 32-fold increase in activity, respectively. It was also able to significantly inhibit the migration of A549 and HK1 cells. Further mode of action studies have shown that the most active analogue, 19, induced DNA damage resulting in G2/M-phase cell- cycle arrest in both cell lines. These events further led to the induction of apoptosis by the compound via caspase-3/7 and caspase-9 activation, PARP cleavage and downregulation of Mcl-1 expression. Moreover, 19 inhibited the expression levels of p-mTOR and p-4EBP1, which indicated that it exerted its anticancer activity, at least in part, via inhibition of the mTOR signalling pathway.

Glucose-dependent growth arrest of leukemia cells by MCT1 inhibition: Feeding Warburg's sweet tooth and blocking acid export as an anticancer strategy

This study aims to investigate the utilization of The Warburg Effect, cancer's "sweet tooth" and natural greed for glucose to enhance the effect of monocarboxylate transporter inhibition on cellular acidification. By simulating hyperglycemia with high glucose we may increase the effectiveness of inhibition of lactate and proton export on the dysregulation of cell pH homeostasis causing cell death or disruption of growth in cancer cells. MCT1 and MCT4 expression was determined in MCF7 and K562 cell lines using RT-PCR. Cell viability, growth, intracellular pH and cell cycle analysis was measured in the cell lines grown in 5 mM and 25 mM glucose containing media in the presence and absence of the MCT1 inhibitor AR-C155858 (1 μM) and the NHE1 inhibitor cariporide (10 μM). The MCT1 inhibitor, AR-C155858 had minimal effect on the viability, growth and intracellular pH of MCT4 expressing MCF7 cells. AR-C155858 had no effect on the viability of the MCT1 expressing K562 cells, but decreased intracellular pH and cell proliferation, by a glucose-dependent mechanism. Inhibition of NHE1 on its own had a no effect on cell growth, but together with AR-C155858 showed an additive effect on inhibition of cell growth. In cancer cells that only express MCT1, increased glucose concentrations in the presence of an MCT1 inhibitor decreased intracellular pH and reduced cell growth by G1 phase cell-cycle arrest. Thus we propose a transient hyperglycemic-clamp in combination with proton export inhibitors be evaluated as an adjunct to cancer treatment in clinical studies.

Magnolol pretreatment attenuates heat stress-induced IEC-6 cell injury

OBJECTIVE

Heat stress (HS) is an important environmental stressor that adversely influences livestock during the summer. The aim of this study was to investigate whether magnolol protects against HS-induced intestinal epithelial cell injury.

MATERIALS AND METHODS

An intestinal epithelial cell line (IEC-6) was subjected to HS at 42 °C, with and without magnolol pretreatment. Cell injury was detected by monitoring lactate dehydrogenase (LDH) release. MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay was used to assess cell proliferation and viability, including identifying effective concentrations of magnolol. Flow cytometry confirmed G1-phase cell-cycle arrest and its alleviation by magnolol. Active DNA synthesis was measured by incorporation of nucleic acid 5-ethynyl-2'-deoxyuridine (EdU). G1-phase cell-cycle-related gene expression was assessed by real-time reverse transcription polymerase chain reaction (RT-PCR) and levels of G1-phase-related proteins by Western blotting.

RESULTS

HS induced IEC-6 cell injury and decreased cell viability, as demonstrated by data from LDH and MTS assays, respectively. Based on a number of criteria, IEC-6 cells subjected to HS were arrested in the G1 phase of the cell cycle. Magnolol pretreatment decreased HS-induced cell injury through relief of this cell-cycle arrest.

CONCLUSIONS

Magnolol pretreatment attenuates HS-induced injury in IEC-6 cells. Magnolol is potentially promising as a protective strategy for HS in livestock.

Enteric glial cells are susceptible to Clostridium difficile toxin B

Clostridium difficile causes nosocomial/antibiotic-associated diarrhoea and pseudomembranous colitis. The major virulence factors are toxin A and toxin B (TcdB), which inactivate GTPases by monoglucosylation, leading to cytopathic (cytoskeleton alteration, cell rounding) and cytotoxic effects (cell-cycle arrest, apoptosis). C. difficile toxins breaching the intestinal epithelial barrier can act on underlying cells, enterocytes, colonocytes, and enteric neurons, as described in vitro and in vivo, but until now no data have been available on enteric glial cell (EGC) susceptibility. EGCs are crucial for regulating the enteric nervous system, gut homeostasis, the immune and inflammatory responses, and digestive and extradigestive diseases. Therefore, we evaluated the effects of C. difficile TcdB in EGCs. Rat-transformed EGCs were treated with TcdB at 0.1-10 ng/ml for 1.5-48 h, and several parameters were analysed. TcdB induces the following in EGCs: (1) early cell rounding with Rac1 glucosylation; (2) early G2/M cell-cycle arrest by cyclin B1/Cdc2 complex inactivation caused by p27 upregulation, the downregulation of cyclin B1 and Cdc2 phosphorylated at Thr161 and Tyr15; and (3) apoptosis by a caspase-dependent but mitochondria-independent pathway. Most importantly, the stimulation of EGCs with TNF-α plus IFN-γ before, concomitantly or after TcdB treatment strongly increased TcdB-induced apoptosis. Furthermore, EGCs that survived the cytotoxic effect of TcdB did not recover completely and showed not only persistent Rac1 glucosylation, cell-cycle arrest and low apoptosis but also increased production of glial cell-derived neurotrophic factor, suggesting self-rescuing mechanisms. In conclusion, the high susceptibility of EGCs to TcdB in vitro, the increased sensitivity to inflammatory cytokines related to apoptosis and the persistence of altered functions in surviving cells suggest an important in vivo role of EGCs in the pathogenesis of C. difficile infection.

Anti-hepatitis B virus (HBV) response of imiquimod based toll like receptor 7 ligand in hbv-positive human hepatocelluar carcinoma cell line

Background

Toll like receptors (TLRs) play an important role in innate immunity and various studies suggest that TLRs play a crucial role in pathogenesis of hepatitis B virus (HBV) infection. The present study aims in looking into the status of crucial host and viral gene expression on inciting TLR7.

Methods

The transcription of TLR7 pathway signaling molecules and HBV DNA viral load were quantified by Real Time-PCR after stimulation of TLR7 with its imiquimod based ligand, R837. Cell cycle analysis was performed using flow-cytometry. Expression of TLR7 and chief cell cycle regulator governing G1/S transition, p53 was also seen in liver biopsysss samples of CHB patients. HBV induced alteration in histone modifications in HepG2 cells and its restoration on TLR7 activation was determined using western blot.

Results

The TLR7 expression remains downregulated in HepG2.2.15 cells and in liver biopsy samples from CHB patients. Interestingly HBV DNA viral load showed an inverse relationship with the TLR7 expression in the biopsy samples. We also evaluated the anti-viral activity of R837, an agonist of TLR7. It was observed that there was a suppression of HBV replication and viral protein production upon TLR7 stimulation. R837 triggers the anti-viral action probably through the Jun N-terminal Kinase (JNK) pathway. We also observed a downregulation of histone H3K9Me3 repression mark upon R837 treatment in HBV replicating HepG2.2.15 cells, mimicking that of un-infected HepG2 cells. Additionally, the G1/S cell cycle arrest introduced by HBV in HepG2.2.15 cells was released upon ligand treatment.

Conclusion

The study thus holds a close insight into the changes in hepatocyte micro-environment on TLR7 stimulation in HBV infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2189-z) contains supplementary material, which is available to authorized users.

Expression and prognostic significance of the autoimmune regulator gene in breast cancer cells

The autoimmune regulator gene (AIRE) plays a fundamental role in tolerance by promoting the expression of tissue-specific antigens in medullary thymic epithelial cells (mTECs). Recently, AIRE expression was detected also in human keratinocytes and in tumors originating in stratified epithelia. Here, we tested whether AIRE is expressed in cancer cells. We analyzed AIRE expression in cancer cases from The Cancer Genome Atlas (TCGA) RNA-seq dataset and we found association with better outcome. AIRE protein expression was verified by immunohistochemistry in a cohort of 39 human breast cancer specimens and its prognostic relevance was confirmed in microarray-based gene expression data set NKI-295 and KM-Plotter. Both in the RNA-seq and gene expression datasets analyzed, AIRE expression was an independent strong prognostic factor for relapse-free survival (RFS), particularly in estrogen receptor-positive tumors. Enrichment of translation-related pathways was observed in AIRE-expressing tumors by Ingenuity Pathway Analysis and a significant increase of cells in G1 phase and activation of caspase cascades was induced by AIRE transfection in breast cancer luminal cell lines, suggesting that AIRE-induced over-translation of proteins lead to cycle arrest and apoptosis. These data are the first to identify AIRE expression in breast cancer and an association with prognosis.

Synthesis and proapoptotic activity of oleanolic acid derived amides

Thirty-one different 3-O-acetyl-OA derived amides have been prepared and screened for their cytotoxic activity. In the SRB assays nearly all the carboxamides displayed good cytotoxicity in the low μM range for several human tumor cell lines. Low EC50 values were obtained especially for the picolinylamides 14-16, for a N-[2-(dimethylamino)-ethyl] derivative 27 and a N-[2-(pyrrolinyl)-ethyl] carboxamide 28. These compounds were submitted to an extensive biological testing and proved compound 15 to act mainly by an arrest of the tumor cells in the S phase of the cell cycle. Cell death occurred by autophagy while compounds 27 and 28 triggered apoptosis.

Gallic acid induces mitotic catastrophe and inhibits centrosomal clustering in HeLa cells

Cancer cells divide rapidly, providing medical targets for anticancer agents. The polyphenolic gallic acid (GA) is known to be toxic for certain cancer cells. However, the cellular mode of action has not been elucidated. Therefore, the current study addressed a potential effect of GA on the mitosis of cancer cells. GA inhibited viability of HeLa cells in a dose-dependent and time-dependent manner. We could show, using fluorescence-activated cell sorting (FACS), that this inhibition was accompanied by elevated frequency of cells arrested at the G2/M transition. This cell-cycle arrest was accompanied by mitotic catastrophe, and formation of cells with multiple nuclei. These aberrations were preceded by impaired centrosomal clustering. We arrive at a model of action, where GA inhibits the progression of the cell cycle at the G2/M phase by impairing centrosomal clustering which will stimulate mitotic catastrophe. Thus, GA has potential as compound against cervical cancer.

Kinesin family member 14 in human oral cancer: A potential biomarker for tumoral growth

Kinesin family member 14 (KIF14), a microtubule-based motor protein, plays an important role in chromosomal segregation, congression, and alignment. Considerable evidence indicates that KIF14 is involved in cytokinesis, although little is known about its role in oral squamous cell carcinomas (OSCCs). In the current study, we functionally and clinically investigated KIF14 expression in patients with OSCC. Quantitative reverse transcriptase–polymerase chain reaction and immunoblotting analyses were used to assess the KIF14 regulatory mechanism in OSCC. Immunohistochemistry (IHC) was performed to analyze the correlation between KIF14 expression and clinical behavior in 104 patients with OSCC. A KIF14 knockdown model of OSCC cells (shKIF14 cells) was used for functional experiments. KIF14 expression was up-regulated significantly (P<0.05) in OSCCs compared with normal counterparts in vitro and in vivo. In addition, shKIF14 cells inhibited cellular proliferation compared with control cells by cell-cycle arrest at the G2/M phase through up-regulation of G2 arrest-related proteins (p-Cdc2 and cyclin B1). As expected, IHC data from primary OSCCs showed that KIF14-positive patients exhibited significantly (P<0.05) more larger tumors compared with KIF14-negative patients. The current results suggest for the first time that KIF14 is an indicator of tumoral size in OSCCs and that KIF14 might be a potential therapeutic target for development of new treatments for OSCCs.

Effects of suberoylanilide hydroxamic acid (SAHA) combined with paclitaxel (PTX) on paclitaxel-resistant ovarian cancer cells and insights into the underlying mechanisms

Background

Suberoylanilide hydroxamic acid (SAHA) is a member of the hydroxamic acid class of the newly developed histone deacetylase inhibitors. Recently, Suberoylanilide hydroxamic acid has attracted increasing attention because of its antitumor activity and synergistic effects in combination with a variety of traditional chemotherapeutic drugs. Paclitaxel (PTX), is a natural anticancer drugs; however, resistance to paclitaxel has become a major challenge to the efficacy of this agent. The purpose of this study was to investigate the effects of the combined application of these two drugs on the paclitaxel-resistant ovarian cancer OC3/P cell line.

Methods

In the present study, the effects of Suberoylanilide hydroxamic acid or/and paclitaxel on OC3/P cells cultured in vitro were analyzed in terms of cell viability, migration, cell-cycle progression and apoptosis by CCK-8, wound healing and flow cytometry assays. Changes in cell ultrastructure were observed by transmission electron microscopy. The expression of genes and proteins related to proliferation, apoptosis and drug resistance were analyzed by quantitative real-time polymerase chain reaction and Western blot analyses.

Results

There was no cross-resistance of the paclitaxel-resistant ovarian cancer OC3/P cells to Suberoylanilide hydroxamic acid. Suberoylanilide hydroxamic acid combined with paclitaxel significantly inhibited cell growth and reduced the migration of OC3/P cells compared with the effects of Suberoylanilide hydroxamic acid or paclitaxel alone. Q-PCR showed the combination of Suberoylanilide hydroxamic acid and paclitaxel reduced intracellular bcl-2 and c-myc gene expression and increased bax gene expression more distinctly than the application of SAHA or paclitaxel alone. Moreover, the level of mdr1 gene expression in cells treated with Suberoylanilide hydroxamic acid was lower than that of the control group (P <0.05). Western blot analysis showed that Suberoylanilide hydroxamic acid alone or in combination with paclitaxel enhanced caspase-3 protein expression and degraded ID1 protein expression in OC3/P cells.

Conclusion

Suberoylanilide hydroxamic acid inhibited the growth of paclitaxel-resistant ovarian cancer OC3/P cells and reduced migration by the induction of cell-cycle arrest, apoptosis and autophagy. These observations indicate the possible synergistic antitumor effects of sequential Suberoylanilide hydroxamic acid and paclitaxel treatment.

Euchromatic histone methyltransferase 2 inhibitor, BIX-01294, sensitizes human promyelocytic leukemia HL-60 and NB4 cells to growth inhibition and differentiation

The involvement of histone lysine methyltransferases (HMT) in carcinogenesis is not well understood. Here, we describe a dose-dependent growth and survival inhibitory effects of BIX-01294, a specific inhibitor of euchromatic HMT2, in promyelocytic leukemia HL-60 and NB4 cells. BIX-01294 combined with all-trans retinoic acid or together with histone deacetylase and DNA methyltransferase inhibitors enhanced cell differentiation to granulocytes and induced cell line-specific changes in the expression of cell cycle-, survival- and differentiation regulating genes and proteins in association with histone modification state. Our results suggest that targeting EHMT2 may be of therapeutical benefits in myeloid leukemia.

²¹³Bi-anti-EGFR radioimmunoconjugates and X-ray irradiation trigger different cell death pathways in squamous cell carcinoma cells

INTRODUCTION

Treatment of patients with squamous cell carcinoma of head and neck is hampered by resistance of tumor cells to irradiation. Additional therapies enhancing the effect of X-ray irradiation may be beneficial. Antibodies targeting EGFR have been shown to improve the efficacy of radiation therapy. Therefore, we analyzed cytotoxicity of (213)Bi-anti-EGFR immunoconjugates in combination with X-ray irradiation.

METHODS

The monoclonal anti-EGFR antibody matuzumab was coupled to CHX-A"-DTPA forming stable complexes with (213)Bi. Cytotoxicity of X-ray radiation, of treatment with (213)Bi-anti-EGFR monoclonal antibodies (MAb) or of a combined treatment regimen was assayed using cell proliferation and colony formation assays in UD-SCC5 cells. Key proteins of cell-cycle arrest and cell death were examined by Western blot analysis. Cell cycle analysis was performed by flow cytometry. DNA double-strand breaks were detected via γH2AX and quantified using Definiens™ software.

RESULTS

Irradiation with X-rays or treatment with (213)Bi-anti-EGFR-MAb resulted in median lethal dose (LD50) values of 12 Gy or 130 kBq/mL, respectively. Treatment with 37 kBq/mL of (213)Bi-anti-EGFR-MAb or 2 Gy of X-rays had only little effect on colony formation of UD-SCC5 cells. In contrast, a combined treatment regimen (37 kBq/mL plus 2 Gy) significantly decreased colony formation and enhanced the formation of DNA double-strand breaks. As revealed by flow cytometry, radiation treatments caused accumulation of cells in the G0/G1 phase. Both treatment with (213)Bi-anti-EGFR immunoconjugates and application of the combined treatment regimen triggered activation of genes of signaling pathways involved in cell-cycle arrest and induction of apoptosis like p21/Waf, GADD45, Puma and Bax, which were only marginally modulated by X-ray irradiation of cells.

CONCLUSIONS

(213)Bi-anti-EGFR-MAb enhances cytotoxicity of X-ray irradiation in UD-SCC5 cells most probably due to effective induction of DNA double-strand breaks. Induction of genes involved in cell-cycle arrest and cell death is almost exclusively due to (213)Bi-anti-EGFR-MAb and seems to be independent of p53 function.

Anticancer Activity of Novel Daphnane Diterpenoids from Daphne genkwa through Cell-Cycle Arrest and Suppression of Akt/STAT/Src Signalings in Human Lung Cancer Cells

Although the immense efforts have been made for cancer prevention, early diagnosis, and treatment, cancer morbidity and mortality has not been decreased during last forty years. Especially, lung cancer is top-ranked in cancer-associated human death. Therefore, effective strategy is strongly required for the management of lung cancer. In the present study, we found that novel daphnane diterpenoids, yuanhualine (YL), yuanhuahine (YH) and yuanhuagine (YG) isolated from the flower of Daphne genkwa (Thymelaeaceae), exhibited potent anti-proliferative activities against human lung A549 cells with the IC₅₀ values of 7.0, 15.2 and 24.7 nM, respectively. Flow cytometric analysis revealed that the daphnane diterpenoids induced cell-cycle arrest in the G0/G1 as well as G2/M phase in A549 cells. The cell-cycle arrests were well correlated with the expression of checkpoint proteins including the up-regulation of cyclin-dependent kinase inhibitor p21 and p53 and down-regulation of cyclin A, cyclin B1, cyclin E, cyclin dependent kinase 4, cdc2, phosphorylation of Rb and cMyc expression. In the analysis of signal transduction molecules, the daphnane diterpenoids suppressed the activation of Akt, STAT3 and Src in human lung cancer cells. The daphnane diterpenoids also exerted the potent anti-proliferative activity against anticancer-drug resistant cancer cells including gemcitabine-resistant A549, gefitinib-, erlotinib-resistant H292 cells. Synergistic effects in the growth inhibition were also observed when yuanhualine was combined with gemcitabine, gefitinib or erlotinib in A549 cells. Taken together, these findings suggest that the novel daphnane diterpenoids might provide lead candidates for the development of therapeutic agents for human lung cancers.

Can RNAi-mediated hsp90α knockdown in combination with 17-AAG be a therapy for glioma?

Heat shock protein 90 promotes tumor progression and survival and has emerged as a vital therapeutic target. Previously we reported that the combinatorial treatment of 17AAG/sihsp90α significantly downregulated Hsp90α mRNA and protein levels in Glioblastoma Multiforme (GBM). Here we investigated the ability of cell penetrating peptide (Tat_48–60 CPP)-mediated siRNA-induced hsp90α knockdown as a single agent and in combination with 17-allylamino-17-demethoxygeldanamycin (17-AAG) to induce tumor growth inhibition in GBM and whether it possessed therapeutic implications. GBM and non-tumorigenic cells exposed to siRNA and/or 17-AAG were subsequently assessed by qRT-PCR, immunofluorescence, FACS analysis, quantitative Akt, LDH leakage and cell viability assays. PAGE was performed for serum stability assessment. A combination of siRNA/17-AAG treatment significantly induced Hsp90α gene and protein knockdown by 95% and 98%, respectively, concomitant to 84% Akt kinase activity attenuation, induced cell cycle arrest and tumor-specific cytotoxicity by 88%. Efficient complex formation between CPP and siRNA exhibited improved serum stability of the siRNA with minimal intrinsic toxicity in vitro. The preliminary in vivo results showed that combination therapy induced hsp90α knockdown and attenuated Akt kinase activity in intracranial glioblastoma mouse models. The results imply that RNAi-mediated hsp90α knockdown increases 17-AAG treatment efficacy in GBM. In addition, the cytotoxic response observed was the consequence of downregulation of hsp90α gene expression, reduced Akt kinase activity and S-G2/M cell cycle arrest. These results are novel and highlight the ability of Tat to efficiently deliver siRNA in GBM and suggest that the dual inhibition of Hsp90 has therapeutic potentials.

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17-AAG–siRNA dual treatment exhibits significant anti-cancer activity in GBM.

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Combination therapy induced Hsp90α gene/protein knockdown causing Akt inactivation.

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Hsp90α inhibition causes S-G2/M cell cycle arrest and GBM-specific cytotoxicity.

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Efficient siRNA/CPP interaction improves serum stability of siRNA.

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RNAi-mediated hsp90α knockdown increases GBM sensitivity to 17-AAG.