Supraphysiological androgens suppress prostate cancer growth through androgen receptor-mediated DNA damage

Prostate cancer (PC) is initially dependent on androgen receptor (AR) signaling for survival and growth. Therapeutics designed to suppress AR activity serve as the primary intervention for advanced disease. However, supraphysiological androgen (SPA) concentrations can produce paradoxical responses leading to PC growth inhibition. We sought to discern the mechanisms by which SPA inhibits PC and to determine if molecular context associates with anti-tumor activity. SPA produced an AR-mediated, dose-dependent induction of DNA double-strand breaks (DSBs), G0/G1 cell cycle arrest and cellular senescence. SPA repressed genes involved in DNA repair and delayed the restoration of damaged DNA which was augmented by PARP1 inhibition. SPA-induced DSBs were accentuated in BRCA2-deficient PCs, and combining SPA with PARP or DNA-PKcs inhibition further repressed growth. Next-generation sequencing was performed on biospecimens from PC patients receiving SPA as part of ongoing Phase II clinical trials. Patients with mutations in genes mediating homology-directed DNA repair were more likely to exhibit clinical responses to SPA. These results provide a mechanistic rationale for directing SPA therapy to PCs with AR amplification or DNA repair deficiency, and for combining SPA therapy with PARP inhibition.

Antiproliferative activity of ionic liquid-graviola fruit extract against human breast cancer (MCF-7) cell lines using flow cytometry techniques

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants have been used for ages by indigenous communities around the world to help humankind sustain its health. Graviola (Annona muricata), also called soursop, is a member of the Annonaceae family and is an evergreen plant that is generally distributed in tropical and subtropical areas of the world. Graviola tree has a long history of traditional use due to its therapeutic potential including anti-inflammatory, antimicrobial, antioxidant, insecticide and cytotoxic to tumor cells.

AIM OF THE STUDY

This study aimed to investigate the in vitro antiproliferative effects and apoptotic events of the ionic liquid extract of Graviola fruit (IL-GFE) on MCF-7 breast cancer cells and their cytokinetics behaviour to observe their potential as a therapeutic alternative in cancer treatment.

MATERIALS AND METHODS

The cell viability assay of the extract was measured using tetrazolium bromide (MTT assay) to observe the effects of Graviola fruit extract. Then the cytokinetics behaviour of MCF-7 cells treated with IL-GFE is observed by plotting the growth curve of the cells. Additionally, the cell cycle distribution and apoptosis mechanism of IL-GFE action on MCF-7 cancer cells were observed by flow cytometry.

RESULTS

IL-GFE exhibited anti-proliferative activity on MCF-7 with the IC50 value of 4.75 μg/mL, compared to Taxol with an IC50 value of 0.99 μg/mL. IL- GFE also reduced the number of cell generations from 3.71 to 1.67 generations compared to 2.18 generations when treated with Taxol. Furthermore, the anti-proliferative activities were verified when the growth rate was decreased dynamically from 0.0077 h to 1 to 0.0035 h-1. Observation of the IL-GFE-treated MCF-7 under microscope demonstrated detachment of cells and loss of density. The growth inhibition of the cells by extracts was associated with cell cycle arrest at the G0/G1 phase, and phosphatidylserine externalisation confirms the anti-proliferation through apoptosis.

CONCLUSIONS

ionic liquid Graviola fruit extract affect the cytokinetics behaviour of MCF-7 cells by reducing cell viability, induce apoptosis and cell cycle arrest at the G0/G1 phase.

Luteolin Shifts Oxaliplatin-Induced Cell Cycle Arrest at G₀/G₁ to Apoptosis in HCT116 Human Colorectal Carcinoma Cells

Certain antioxidative flavonoids are known to activate nuclear factor E2-related factor 2 (Nrf2), a transcription factor that regulates cellular antioxidants and detoxifying response and is reportedly highly activated in many types of cancers. Few studies on the potential undesired effects of flavonoid intake during chemotherapy have been conducted, yet Nrf2 activators could favor cancer cell survival by attenuating chemotherapeutic efficiency. This study aimed to examine if luteolin, an Nrf2 activator, hinders chemotherapeutic activity of oxaliplatin, a potent anticancer agent for colorectal cancer, in HCT116 cells. Luteolin treatment strongly increased the transcriptional activity of the antioxidant response element in HCT116 cells and induced the protein expression of heme oxygenase-1, which were indicative of its Nrf2-inducing potential. Intriguingly, 25 μM luteolin reduced cell viability through apoptotic induction, which was intensified in p53-expressing cells while 1 μM oxaliplatin caused cell cycle arrest at G₀/G₁-phase via the p53/p21-dependent mechanism. Moreover, luteolin treatment was found to reduce oxaliplatin-treated p53-null cell viability and colony counts further, thereby demonstrating an additional effect of luteolin in the killing of human colorectal tumor HCT116 cells not expressing functional p53 protein. The findings suggest that luteolin can induce p53-mediated apoptosis regardless of oxaliplatin treatment and may eliminate oxaliplatin-resistant p53-null colorectal cells.

RETRACTED: Brazilein induces apoptosis and G1/G0 phase cell cycle arrest by up-regulation of miR-133a in human vestibular schwannoma cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Given the comments of Dr Elisabeth Bik regarding this article “... the Western blot bands in all 400+ papers are all very regularly spaced and have a smooth appearance in the shape of a dumbbell or tadpole, without any of the usual smudges or stains. All bands are placed on similar looking backgrounds, suggesting they were copy/pasted from other sources, or computer generated”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Ginger polysaccharides induced cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells

In this study, ginger polysaccharide (GP) was obtained from ginger by enzymatic method, its chemical properties and antitumor activity were investigated. The results indicated that the composition and proportion of GP were l‑rhamnose, d‑arabinose, d‑mannose, d‑glucose and d‑galactose in a molar ratio of 3.64:5.37:3.04:61.03:26.91, GP had the characteristic absorption peak of polysaccharide. Congo red experiment showed that GP had a triple helix structure, which could have anti-tumor effect. Furthermore, MTT assay, cell morphology observation, nuclear morphology observation and reactive oxygen species observation demonstrated that GP had significant antitumor effect. Flow cytometry suggested that GP could promote apoptosis and arrest cells in G0-G1 phase. Real-time fluorescence quantification and Western blot revealed that GP could up-regulate the expression of Bax, Fas, FasL, caspase-3, p21 and p53, and down-regulate the expression of Bcl-2. These studies suggested that GP would be used as an antitumor drug in foods to promote the development of functional foods.

Cannabinoid WIN 55,212-2 induces cell cycle arrest and apoptosis, and inhibits proliferation, migration, invasion, and tumor growth in prostate cancer in a cannabinoid-receptor 2 dependent manner

BACKGROUND

Cannabinoids have demonstrated anticarcinogenic properties in a variety of malignancies, including in prostate cancer. In the present study, we explored the anti-cancer effects of the synthetic cannabinoid WIN 55,212-2 (WIN) in prostate cancer.

METHODS

Established prostate cancer cells (PC3, DU145, LNCaP) were treated with varying concentrations of WIN. Cell proliferation was determined by the MTS assay. The anti-migration and anti-invasive potential of WIN was examined by the wound healing assay and the matrigel invasion assay. Cell cycle analysis was performed by flow cytometry, and mechanistic studies were performed by Western blot. Athymic mice (n = 10) were inoculated with human PC3 cells. Once tumors reached 100 mm³ , animals were randomized into two groups: saline control and WIN (5 mg/kg), delivered by intraperitoneal injection three times per week for 3 weeks.

RESULTS

WIN significantly reduced prostate cancer cell proliferation, migration, invasion, induced apoptosis, and arrested cells in Go/G1 phase in a dose-dependent manner. Mechanistic studies revealed these effects were mediated through a pathway involving cell cycle regulators p27, Cdk4, and pRb. Pre-treatment with a CB₂ antagonist, AM630, followed by treatment with WIN resulted in a reversal of the anti-proliferation and cell cycle arrest previously seen with WIN alone. In vivo, administration of WIN resulted in a reduction in the tumor growth rate compared to control (P < 0.05).

CONCLUSIONS

The following study provides evidence supporting the use of WIN as a novel therapeutic for prostate cancer.

The antipsychotic agent trifluoperazine hydrochloride suppresses triple-negative breast cancer tumor growth and brain metastasis by inducing G0/G1 arrest and apoptosis

Women with aggressive triple-negative breast cancer (TNBC) are at high risk of brain metastasis, which has no effective therapeutic option partially due to the poor penetration of drugs across the blood-brain barrier. Trifluoperazine (TFP) is an approved antipsychotic drug with good bioavailability in brain and had shown anticancer effect in several types of cancer. It drives us to investigate its activities to suppress TNBC, especially the brain metastasis. In this study, we chose three TNBC cell lines MDA-MB-468, MDA-MB-231, and 4T1 to assess its anticancer activities along with the possible mechanisms. In vitro, it induced G0/G1 cell cycle arrest via decreasing the expression of both cyclinD1/CDK4 and cyclinE/CDK2, and stimulated mitochondria-mediated apoptosis. In vivo, TFP suppressed the growth of subcutaneous xenograft tumor and brain metastasis without causing detectable side effects. Importantly, it prolonged the survival of mice bearing brain metastasis. Immunohistochemical analysis of Ki67 and cleaved caspase-3 indicated TFP could suppress the growth and induce apoptosis of cancer cells in vivo. Taken together, TFP might be a potential available drug for treating TNBC with brain metastasis, which urgently needs novel treatment options.

Disulfiram/copper causes ROS levels alteration, cell cycle inhibition, and apoptosis in acute myeloid leukaemia cell lines with modulation in the expression of related genes

The majority of acute myeloid leukaemia (AML) patients will die from their disease or therapy-related complications. There is an inevitable need to improve the survival of AML patients. Previous studies show that disulfiram (DSF), an anti-alcoholism drug with a low toxicity profile, demonstrates anticancer behaviors. Here, we evaluated the cytotoxicity and mechanistic action of DSF on the AML cell lines KG-1, NB4, and U937. The microculture tetrazolium test revealed that DSF alone or in combination with copper (Cu) is highly toxic to the AML cells at concentrations lower than those achievable in the clinical setting, with Cu increasing the DSF-induced inhibition of metabolic activity. Flow cytometric analysis and QRT-PCR indicated that in the two cell lines, NB4 and U-937, DSF/Cu increased reactive oxygen species (ROS) levels in association with the induction of superoxide dismutase 2 (SOD2) expression and suppression of catalase (CAT). In the KG-1 cell line, DSF/Cu reduced the ROS levels in agreement with the induction of CAT expression. The cell cycle and apoptosis assessment by flow cytometry demonstrated that DSF/Cu induced G0/G1 cell cycle arrest and apoptosis. These were associated with the increased expression of FOXO tumor suppressors, decreased expression of the MYC oncogene and the modulation of their known target genes related to the cell cycle and apoptosis. Therefore, DSF/Cu caused the disturbance of the ROS balance, cell cycle arrest and apoptosis in AML cells in coordination with the modulation in expression of their related genes. These results propose the possible use of DSF in AML therapies.

NBS1 is regulated by two kind of mechanisms: ATM-dependent complex formation with MRE11 and RAD50, and cell cycle-dependent degradation of protein

Nijmegen breakage syndrome (NBS), a condition similar to Ataxia-Telangiectasia (A-T), is a radiation-hypersensitive genetic disorder showing chromosomal instability, radio-resistant DNA synthesis, immunodeficiency, and predisposition to malignances. The product of the responsible gene, NBS1, forms a complex with MRE11 and RAD50 (MRN complex). The MRN complex is necessary for the DNA damage-induced activation of ATM. However, the regulation of MRN complex formation is still unclear. Here, we investigated the regulatory mechanisms of MRN complex formation. We used an immunoprecipitation assay to determine whether levels of the MRN complex were increased by radiation-induced DNA damage and found that the levels of these proteins and their mRNAs did not increase. ATM-dependent phosphorylation of NBS1 contributed to the DNA damage-induced MRN complex formation. However, pre-treatment of cells with an ATM-specific inhibitor did not affect homologous recombination (HR) and non-homologous end-joining (NHEJ) repair. G0 phase cells, decreasing NBS1 and HR activity but not NHEJ, gained HR-related chromatin association of RAD51 by overexpression of NBS1, suggesting that the amount of NBS1 may be important for repressing accidental activation of HR. These evidences suggest that NBS1 is regulated by two kind of mechanisms: complex formation dependent on ATM, and protein degradation mediated by an unknown MG132-resistant pathway. Such regulation of NBS1 may contribute to cellular responses to double-strand breaks.

Quercetin simultaneously induces G0 /G1 -phase arrest and caspase-mediated crosstalk between apoptosis and autophagy in human leukemia HL-60 cells

Quercetin is a plant-derived bioflavonoid with high anticancer activity in various tumors. Herein, the molecular mechanisms by which quercetin exerts its anticancer effects against HL-60 acute myeloid leukemia (AML) cells were investigated. Results showed that quercetin suppressed cell proliferation in the HL-60 cell line in vitro and in vivo. Quercetin-induced G₀ /G₁ -phase arrest occurred when expressions of cyclin-dependent kinase (CDK)2/4 were inhibited and the CDK inhibitors, p16 and p21, were induced. Moreover, quercetin treatment not only activated proapoptotic signaling like poly (ADP ribose) polymerase (PARP)-1 cleavage and caspase activation but also triggered autophagy events as shown by the increased expression of light chain 3 (LC3)-II, decreased expression of p62, and formation of acidic vesicular organelles. Interestingly, it was found that use of the autophagy inhibitor, 3-methyladenine, significantly enhanced quercetin-mediated apoptotic cell death as analyzed by MTS and DNA fragmentation assays. Moreover, pretreatment of HL-60 cells with the pan-caspase inhibitor, Z-VAD-fmk, dramatically reversed quercetin-mediated apoptotic and autophagic cell death. Although apoptosis and autophagy are two independent cell death pathways, our findings indicated that quercetin can activate caspases to trigger these two pathways, and both pathways played contrary roles in quercetin-mediated HL-60 cell death. In conclusion, besides promoting apoptosis, quercetin also induced cytoprotective autophagy in HL-60 cells, and inhibition of autophagy may be a novel strategy to enhance the anticancer activity of quercetin in AML.

Cytotoxic and apoptosis-inducing activity of C21 steroids from the roots of Cynanchum atratum

Two new (1-2) and two known C₂₁ steroids (3-4) were isolated from the roots of Cynanchum atratum. Their structures were elucidated by detailed 1D and 2D spectroscopic. The MTT assay showed that compounds 1-4 displayed obvious cytotoxic activities against HepG2 cells with IC₅₀ values ranging from 10.19μM to 76.12μM. Compounds 1-3 also exhibited cytotoxic effects in A549 cells with IC₅₀ values of 30.87-95.39μM. Compound 3 showed the antiproliferative activity via G0/G1 cell cycle arrest and proapoptosis in HepG2 cells by Flowcytometry analysis. Western blotting analysis revealed that compound 3 could induce HepG2 cell apoptosis via the mitochondrial pathway by downregulating Bcl-2 expression, upregulating Bax protein expression, and activating caspase-9 and caspase-3.

Chidamide in FLT3-ITD positive acute myeloid leukemia and the synergistic effect in combination with cytarabine

Chidamide, a novel histone deacetylase inhibitor (HDACi), has been approved for treatment of T-cell lymphomas in multiple clinical trials. It has been demonstrated that chidamide can inhibit cell cycle, promote apoptosis and induce differentiation in leukemia cells, whereas its effect on acute myeloid leukemia (AML) patients with FLT3-ITD mutation has not been clarified. In this study, we found that chidamide specifically induced G0/G1 arrest and apoptosis in FLT3-ITD positive AML cells in a concentration and time-dependent manner. We also found chidamide had the cytotoxicity effect on FLT3-ITD positive and negative AML cells. Moreover, with respect to relapsed/refractory patients, chidamide showed the same effectiveness as that in de novo AML patients. Notably, chidamide synergistically enhanced apoptosis caused by cytarabine. Our results support chidamide alone or combine with cytarabine may be used as an alternative therapeutic choice for AML patients especially those with FLT3-ITD mutation or relapsed/refractory ones.

Sorafenib and 2-Deoxyglucose Synergistically Inhibit Proliferation of Both Sorafenib-Sensitive and -Resistant HCC Cells by Inhibiting ATP Production

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths globally. Sorafenib is the only first-line systemic drug for advanced HCC, but it has very limited survival benefits because patients treated with sorafenib either suffer from side effects or show disease progression after initial response. Thus, there is an urgent need to develop novel strategies for first-line and second-line therapies. The association between sorafenib resistance and glycolysis prompted us to screen several drugs with known antiglycolytic activity to identify those that will sensitize cells to sorafenib. We demonstrate that the combination of glycolytic inhibitor 2-deoxyglucose (2DG) and sorafenib drastically inhibits viability of sorafenib-sensitive and -resistant cells. However, the combination of other antiglycolytic drugs like lonidamine, gossypol, 3-bromopyruvate, and imatinib with sorafenib does not show synergistic effect. Cell cycle analysis revealed that the combination of 2DG and sorafenib induced cell cycle arrest at G0/G1. Mechanistic investigation suggests that the cell cycle arrest is due to depletion of cellular ATP that activates AMP-activated protein kinase (AMPK), which, in turn, inhibits mammalian target of rapamycin (mTOR) to induce cell cycle arrest. This study provides strong evidence for the therapeutic potential of the combination of sorafenib and 2DG for HCC.

The Integrins Involved in Soybean Agglutinin-Induced Cell Cycle Alterations in IPEC-J2

Soybean agglutinin (SBA) is an anti-nutritional factor of soybean, affecting cell proliferation and inducing cytotoxicity. Integrins are transmembrane receptors, mediating a variety of cell biological processes. This research aims to study the effects of SBA on cell proliferation and cell cycle progression of the intestinal epithelial cell line from piglets (IPEC-J2), to identify the integrin subunits especially expressed in IPEC-J2s, and to analyze the functions of these integrins on IPEC-J2 cell cycle progression and SBA-induced IPEC-J2 cell cycle alteration. The results showed that SBA lowered cell proliferation rate as the cell cycle progression from G0/G1 to S phase (P < 0.05) was inhibited. Moreover, SBA lowered mRNA expression of cell cycle-related gene CDK4, Cyclin E and Cyclin D1 (P < 0.05). We successfully identified integrins α2, α3, α6, β1, and β4 in IPEC-J2s. These five subunits were crucial to maintain normal cell proliferation and cell cycle progression in IPEC-J2s. Restrain of either these five subunits by their inhibitors, lowered cell proliferation rate, and arrested the cells at G0/G1 phase of cell cycle (P < 0.05). Further analysis indicated that integrin α2, α6, and β1 were involved in the blocking of G0/G1 phase induced by SBA. In conclusion, these results suggested that SBA lowered the IPEC-J2 cell proliferation rate through the perturbation of cell cycle progression. Furthermore, integrins were important for IPEC-J2 cell cycle progression, and they were involved in the process of SBA-induced cell cycle progression alteration, which provide a basis for further revealing SBA anti-proliferation and anti-nutritional mechanism.

Anti-proliferative properties of commercial Pelargonium sidoides tincture, with cell-cycle G0/G1 arrest and apoptosis in Jurkat leukaemia cells

Context Pelargonium sidoides DC (Geraniaceae) is an important medicinal plant indigenous to South Africa and Lesotho. Previous studies have shown that root extracts are rich in polyphenolic compounds with antibacterial, antiviral and immunomodulatory activities. Little is known regarding the anticancer properties of Pelargonium sidoides extracts. Objective This study evaluates the anti-proliferative effects of a Pelargonium sidoides radix mother tincture (PST). Materials and methods The PST was characterized by LC-MS/MS. Anti-proliferative activity was evaluated in the pre-screen panel of the National Cancer Institute (NCI-H460, MCF-7 and SF-268) and the Jurkat leukaemia cell line at concentrations of 0-150 μg/mL. The effect on cell growth was determined with sulphorhodamine B and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays after 72 h. The effect on cell cycle and apoptosis induction in Jurkat cells was determined by flow cytometry with propidium iodide and Annexin V: fluorescein isothiocyanate staining. Results Dihydroxycoumarin sulphates, gallic acid as well as gallocatechin dimers and trimers were characterized in PST by mass spectrometry. Moderate anti-proliferative effects with GI50 values between 40 and 80 μg/mL were observed in the NCI-pre-screen panel. Strong activity observed with Jurkat cells with a GI50 value of 6.2 μg/mL, significantly better than positive control 5-fluorouracil (GI50 value of 9.7 μg/mL). The PST arrested Jurkat cells at the G0/G1 phase of the cell cycle and increased the apoptotic cells from 9% to 21%, while the dead cells increased from 4% to 17%. Conclusion We present evidence that P. sidoides has cancer cell type-specific anti-proliferative effects and may be a source of novel anticancer molecules.

Tideglusib induces apoptosis in human neuroblastoma IMR32 cells, provoking sub-G0/G1 accumulation and ROS generation

Neuroblastoma is the most common tumor amongst children amounting to nearly 15% of cancer deaths. This cancer is peculiar in its characteristics, exhibiting differentiation, maturation and metastatic transformation leading to poor prognosis and low survival rates among children. Chemotherapy, though toxic to normal cells, has shown to improve the survival of the patient with emphasis given more towards targeting angiogenesis. Recently, Tideglusib was designed as an 'Orphan Drug' to target the neurodegenerative Alzheimer's disease and gained significant momentum in its function during clinical trials. Duffy et al. recently reported a reduction in cell viability of human IMR32 neuroblastoma cells when treated with Tideglusib at varying concentrations. We investigated the effects of Tideglusib, at various concentrations, compared to Lithium chloride at various concentrations, on IMR32 cells. Lithium, a known GSK-3 inhibitor, was used as a standard to compare the efficiency of Tideglusib in a dose-dependent manner. Cell viability was assessed by MTT assay. The stages of apoptosis were evaluated by AO/EB staining and nuclear damage was determined by Hoechst 33258 staining. Reactive oxygen species (ROS) and mitochondrial membrane potential (ΔΨm) were assessed by DCFDA dye and Rhodamine-123 dye, respectively. Tideglusib reported a significant dose-dependent increase in pro-apoptotic proteins (PARP, Caspase-9, Caspase-7, Caspase-3) and tumor-related genes (FasL, TNF-α, Cox-2, IL-8, Caspase-3). Anti-GSK3 β, pGSK3 β, Bcl-2, Akt-1, p-Akt1 protein levels were observed with cells exposed to Tideglusib and Lithium chloride. No significant dose-dependent changes were observed for the mRNA expression of collagenase MMP-2, the tumor suppressor p53, or the cell cycle protein p21. Our study also reports Tideglusib reducing colony formation and increasing the level of sub-G0/G1 population in IMR32 cells. Our investigations report the significance of Tideglusib as a promising apoptotic inducer in human neuroblastoma IMR32 cells. Our study also reports that LiCl reduced cell viability in IMR32 cells inducing apoptosis mediated by ROS generation.

Monobenzyltin Complex C1 Induces Apoptosis in MCF-7 Breast Cancer Cells through the Intrinsic Signaling Pathway and through the Targeting of MCF-7-Derived Breast Cancer Stem Cells via the Wnt/β-Catenin Signaling Pathway

Monobenzyltin Schiff base complex, [N-(3,5-dichloro-2-oxidobenzylidene)-4-chlorobenzyhydrazidato](o-methylbenzyl)aquatin(IV) chloride, C1, is an organotin non-platinum metal-based agent. The present study was conducted to investigate its effects on MCF-7 cells with respect to the induction of apoptosis and its inhibitory effect against MCF-7 breast cancer stem cells. As determined in a previous study, compound C1 revealed strong antiproliferative activity on MCF-7 cells with an IC₅₀ value of 2.5 μg/mL. Annexin V/propidium iodide staining coupled with flow cytometry indicated the induction of apoptosis in treated cells. Compound C1 induced apoptosis in MCF-7 cells and was mediated through the intrinsic pathway with a reduction in mitochondrial membrane potential and mitochondrial cytochrome c release to cytosol. Complex C1 activated caspase 9 as a result of cytochrome c release. Subsequently, western blot and real time PCR revealed a significant increase in Bax and Bad expression and a significant decrease in the expression levels of Bcl2 and HSP70. Furthermore, a flow cytometric analysis showed that treatment with compound C1 caused a significant arrest of MCF-7 cells in G0/G1 phase. The inhibitory analysis of compound C1 against derived MCF-7 stem cells showed a significant reduction in the aldehyde dehydrogenase-positive cell population and a significant reduction in the population of MCF-7 cancer stem cells in primary, secondary, and tertiary mammospheres. Moreover, treatment with C1 down-regulated the Wnt/β-catenin self-renewal pathway. These findings indicate that complex C1 is a suppressive agent of MCF-7 cells that functions through the induction of apoptosis, cell cycle arrest, and the targeting of MCF-7-derived cancer stem cells. This work may lead to a better treatment strategy for the reduction of breast cancer recurrence.

Low Oxygen Tension Enhances Expression of Myogenic Genes When Human Myoblasts Are Activated from G0 Arrest

OBJECTIVES

Most cell culture studies have been performed at atmospheric oxygen tension of 21%, however the physiological oxygen tension is much lower and is a factor that may affect skeletal muscle myoblasts. In this study we have compared activation of G0 arrested myoblasts in 21% O2 and in 1% O2 in order to see how oxygen tension affects activation and proliferation of human myoblasts.

MATERIALS AND METHODS

Human myoblasts were isolated from skeletal muscle tissue and G0 arrested in vitro followed by reactivation at 21% O2 and 1% O2. The effect was assesses by Real-time RT-PCR, immunocytochemistry and western blot.

RESULTS AND CONCLUSIONS

We found an increase in proliferation rate of myoblasts when activated at a low oxygen tension (1% O2) compared to 21% O2. In addition, the gene expression studies showed up regulation of the myogenesis related genes PAX3, PAX7, MYOD, MYOG (myogenin), MET, NCAM, DES (desmin), MEF2A, MEF2C and CDH15 (M-cadherin), however, the fraction of DES and MYOD positive cells was not increased by low oxygen tension, indicating that 1% O2 may not have a functional effect on the myogenic response. Furthermore, the expression of genes involved in the TGFβ, Notch and Wnt signaling pathways were also up regulated in low oxygen tension. The differences in gene expression were most pronounced at day one after activation from G0-arrest, thus the initial activation of myoblasts seemed most sensitive to changes in oxygen tension. Protein expression of HES1 and β-catenin indicated that notch signaling may be induced in 21% O2, while the canonical Wnt signaling may be induced in 1% O2 during activation and proliferation of myoblasts.

Tubeimoside-1 induces oxidative stress-mediated apoptosis and G0/G1 phase arrest in human prostate carcinoma cells in vitro

AIM

Tubeimoside-1 (TBMS1), a triterpenoid saponin extracted from the Chinese herbal medicine Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), has shown anticancer activities in various cancer cell lines. The aim of this study was to investigate the anticancer activity and molecular targets of TBMS1 in human prostate cancer cells in vitro.

METHODS

DU145 and P3 human prostate cancer cells were treated with TBMS1. Cell viability and apoptosis were detected. ROS generation, mitochondrial membrane potential and cell cycle profile were examined. Western blotting was used to measure the expression of relevant proteins in the cells.

RESULTS

TBMS1 (5-100 μmol/L) significantly suppressed the viability of DU145 and P3 cells with IC50 values of approximately 10 and 20 μmol/L, respectively. Furthermore, TBMS1 dose-dependently induced apoptosis and cell cycle arrest at G0/G1 phase in DU145 and P3 cells. In DU145 cells, TBMS1 induced mitochondrial apoptosis, evidenced by ROS generation, mitochondrial dysfunction, endoplasmic reticulum stress, modulated Bcl-2 family protein and cleaved caspase-3, and activated ASK-1 and its downstream targets p38 and JNK. The G0/G1 phase arrest was linked to increased expression of p53 and p21 and decreased expression of cyclin E and cdk2. Co-treatment with Z-VAD-FMK (pan-caspase inhibitor) could attenuate TBMS1-induced apoptosis but did not prevent G0/G1 arrest. Moreover, co-treatment with NAC (ROS scavenger), SB203580 (p38 inhibitor), SP600125 (JNK inhibitor) or salubrinal (ER stress inhibitor) significantly attenuated TBMS1-induced apoptosis.

CONCLUSION

TBMS1 induces oxidative stress-mediated apoptosis in DU145 human prostate cancer cells in vitro via the mitochondrial pathway.

Cytotoxic biomonitored study of Euphorbia umbellata (Pax) Bruyns

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia umbellata latex (sap) has normally been used in folk medicine in southern Brazil to treat different types of cancers.

AIM OF STUDY

To carry out a biomonitored investigation of partitioned latex using in vitro assay, to identify the main mechanisms related with the action of the most active fraction as well as to develop a phytochemical study with this material.

MATERIALS AND METHODS

Biological screening was performed with hexane, chloroform, ethyl acetate and methanol fractions from the latex of E. umbellata using MTT, trypan blue, and neutral red assays to determine the cytotoxicity against HRT-18, HeLa and Jurkat cells and flow cytometry, DNA quantification, acridine orange and Hoechst 33342 staining to investigate mechanisms of action for the hexane extract. The phytochemical study of the hexane fraction was performed by chromatographic procedures and the substances were identified by NMR analysis. The isolated terpenes were evaluated using MTT to determine the cytotoxicity against Jurkat cells.

RESULTS

All the fractions presented concentration and time dependent cytotoxicity. The hexane fraction showed the highest cytotoxicity; whereas the Jurkat cell was the lineage with the highest sensitivity (IC50 1.87µg/mL). Fragmentation of DNA and apoptosis are two mechanisms related with the toxicity of hexane fraction. The hexane fraction arrested the cell cycle in the G0/G1 phase, and the selectivity index was 4.30. Phytochemical study of the hexane fraction led to isolation of euphol (main compound) and germanicol acetate. Both substances demonstrated some slight cytotoxic activity against Jurkat cells after 72h; however the activity was minimal compared to vincristine (anticancer standard drug).

CONCLUSION

The current research proves that the fractions of the latex from E. umbellata have a cytotoxic effect against three different cancer cells lines. The hexane fraction showed high in vitro cytotoxic effects against Jurkat cells demonstrating that the effect may be due to non-polar constituents. The two isolated terpenes (euphol and germanicol acetate) showed poor cytotoxic activity indicating that the anticancer properties of the extract may be caused by other substances present in the hexane fraction.

Chain elongation analog of resveratrol as potent cancer chemoprevention agent

Resveratrol is identified as a natural cancer chemoprevention agent. There has been a lot of interest in designing and developing resveratrol analogs with cancer chemoprevention activity superior to that of parent molecule and exploring their action mechanism in the past several decades. In this study, we have synthesized resveratrol analogs of compounds A-C via conjugated chain elongation based on isoprene unit retention strategy. Remarkably, cytotoxic activity analysis results indicated that compound B possesses the best proliferation inhibition activity for NCI-H460 cells in all the test compounds. Intriguingly, compound B displayed a higher cytotoxicity against human non-small cell lung cancer cells (NCI-H460) compared to normal human embryonic lung fibroblasts (MRC-5). Afterward, flow cytometry analysis showed that compound B would induce cell apoptosis. We further researched the action mechanism. When NCI-H460 cells were incubated by compound B for 6 or 9 h, respectively, the intracellular reactive oxygen species (ROS) level was enhanced obviously. With elevation of intracellular ROS level, flow cytometry measurement verified mitochondrial transmembrane potential collapse, which was accompanied by the up-regulation of Bax and down-regulation of Bcl-2. More interestingly, compound B increased the expression of caspase-9 and caspase-3, which induced cell apoptosis. Moreover, compound B arrested cell cycle in G0/G1 phase. These are all to provide useful information for designing resveratrol-based chemoprevention agent and understanding the action mechanism.

Vasculoprotective Effects of 3-Hydroxybenzaldehyde against VSMCs Proliferation and ECs Inflammation

3-hydroxybenzaldehyde (3-HBA) is a precursor compound for phenolic compounds like Protocatechuic aldehyde (PCA). From recent reports, PCA has shown vasculoprotective potency, but the effects of 3-HBA remain unclear. The aim of this study is to investigate the vasculoprotective effects of 3-HBA in endothelial cells, vascular smooth muscle cells and various animal models. We tested effects of 3-HBA in both vitro and vivo. 3-HBA showed that it prevents PDGF-induced vascular smooth muscle cells (VSMCs) migration and proliferation from MTS, BrdU assays and inhibition of AKT phosphorylation. It arrested S and G0/G1 phase of VSMC cell cycle in PI staining and it also showed inhibited expression levels of Rb1 and CD1. In human umbilical vein endothelial cells (HUVECs), 3-HBA inhibited inflammatory markers and signaling molecules (VCAM-1, ICAM-1, p-NF-κB and p-p38). For ex vivo, 3-HBA has shown dramatic effects in suppressing the sprouting from aortic ring of Spargue Dawley (SD) rats. In vivo data supported the vasculoprotective effects of 3-HBA as it inhibited angiogenesis from Matrigel Plug assay in C57BL6 mouse, prevented ADP-induced thrombus generation, increased blood circulation after formation of thrombus, and attenuated neointima formation induced by common carotid artery balloon injury of SD rats. 3-HBA, a novel therapeutic agent, has shown vasculoprotective potency in both in vitro and in vivo.

Purification of Lovastatin from Aspergillus terreus (KM017963) and Evaluation of its Anticancer and Antioxidant Properties

Cervical cancer is the second most common malignancy in women worldwide and thus one of the leading causes of mortality in women. Lovastatin, a non polar, anticholesterol drug has previously been reported to exert antitumour activity in vitro. In the present study, lovastatin from Aspergillus terreus (KM017963) was purified by adsorption chromatography and evaluated for its anticancer and anti-oxidant properties with a human cervical cancer cell line (HeLa). Growth inhibitory and proapoptotic effects of purified lovastatin on HeLa cells were investigated by determining its influence on cell numbers, mitochondrial membrane potential (MMP), DNA fragmentation and antioxidant properties in terms of hydroxy radical scavenging effects as well as levels of total reduced glutathione. Cell cycle analysis by ow cytometry (propidium iodide staining) confirmed induction of apoptotic cell death and revealed cell cycle arrest in the G0/G1 phase. The results of the study give leads for the anticancer effects of lovastatin and its potential usefulness in the chemotherapy of cervical cancer.

Effect of apigenin-7-glucoside, genkwanin and naringenin on tyrosinase activity and melanin synthesis in B16F10 melanoma cells

AIMS

In this study, we have investigated the effects of apigenin-7-glucoside, genkwanin and naringenin, on mouse melanoma B16F10 cell proliferation. Influence of these natural products on percentage cell distribution in cycle phases and melanogenesis was also studied.

MAIN METHODS

Cell viability was determined at various periods using the MTT assay, whereas effects of tested compounds on progression through the cell cycle were analyzed by flow cytometry. In addition, amounts of melanin and tyrosinase were measured spectrophotometrically at 475 nm. Besides, the mechanism involved on the death route induced by the tested molecules was evaluated using the bis-benzimide trihydrochloride coloration method (Hoechst 33258).

KEY FINDINGS

Apigenin-7-glucoside, genkwanin and naringenin exhibited significant anti-proliferative activity against B16F10 melanoma cells after 24 and 48 h of incubation. Furthermore, apigenin-7-glucoside, genkwanin and naringenin provoked an increase of subG0/G1, S and G2/M phase cell proportion with a significant decrease of cell proportion in G0/G1 phases. The results evaluated using Hoechst 33,258, confirm that the percentage of B16F10 cells observed in the sub G0/G1 phase were undergoing apoptosis. Moreover, apigenin-7-glucoside and naringenin revealed an ability to enhance melanogenesis synthesis and tyrosinase activity of B16F10 melanoma cells. Whereas genkwanin induces a decrease of melanin synthesis by inhibiting tyrosinase activity.

SIGNIFICANCE

Our results promote the introduction of genkwanin in cosmetic preparations, as skin whitening agent, whereas apigenin-7-glucoside and naringenin should be introduced into cosmetic products as natural tanning agents.

Lentivirus-mediated knockdown of CTDP1 inhibits lung cancer cell growth in vitro

BACKGROUND

CTDP1 catalyzes serine phosphorylation and dephosphorylation of the mobile carboxy-terminal domain of the RNA polymerase II. It is conserved among eukarya and is essential for cell growth for its ability in regulation of transcription machinery. However, its function in the process of tumorigenesis is unclear. In the present study, we aim to explore the roles of CTDP1 in the progression of human lung cancer. To our knowledge, this is the first study that reports the functions of CTDP1 in human lung cancer.

METHODS

We first detected the expression level of CTDP1 in four human lung cancer cell lines: H-125, H1299, LTEP-A-2 and NCI-H446 by semiquantitative RT-PCR. We compared the expression level of CTDP1 in lung cancer tissues and paired adjacent normal tissues on 29 pathologically confirmed patients by real-time quantitative PCR. To further explore the effect of CTDP1 on cell proliferation, a lentiviral vector expressing CTDP1 short hairpin RNA (shRNA) was constructed and infected into human lung cell lines H1299. Interference efficiency was determined by western blot analysis and real-time quantitative PCR. The effects of knockdown of CTDP1 on cell growth, cell cycle and apoptosis and cell colony formation were explored by Cellomics, fluorescence-activated cells sorting and fluorescence microscopy, respectively.

RESULTS

CTDP1 was expressed in all four human lung cancer cell lines. The expression of CTDP1 in tumor tissues was significantly higher than paired adjacent normal tissues in 29 patients with lung cancer. The expression of CTDP1 was markedly reduced in cells infected with lentivirus delivering shRNA against CTDP1. Inhibition of CTDP1 expression significantly suppressed cell growth, induced G0/G1 phase arrest and repressed cell colony formation.

CONCLUSIONS

Our results demonstrated that CTDP1 was upregulated in human lung cancer tissues. In addition, it implied that CTDP1 played an important role in cell proliferation and may be a useful therapeutic target in human lung cancer.