Cell Cycle Arrest In G0-G1 Phase Research Articles

Pyridazinone-based derivatives as anticancer agents endowed with anti-microbial activity: molecular design, synthesis, and biological investigation.

Cancer patients undergoing chemotherapy are highly susceptible to infections owing to their compromised immune system, which also promotes cancer progression through inflammation. Thus, this study aimed to develop novel chemotherapeutic agents with both anticancer and antimicrobial properties. A series of diarylurea derivatives based on pyridazinone scaffolds were designed, synthesized, and characterized as surrogates for sorafenib. The synthesized compounds were tested for their antimicrobial activity and screened against 60 cancer cell lines at the National Cancer Institute (NCI). Compound 10h exhibited potent antibacterial activity against Staphylococcus aureus (MIC = 16 μg mL-1), whereas compound 8g showed significant antifungal activity against Candida albicans (MIC = 16 μg mL-1). Additionally, ten compounds were further evaluated for VEGFR-2 inhibition, with compound 17a showing the best inhibitory activity. Compounds 8f, 10l, and 17a demonstrated significant anticancer activity against melanoma, NSCLC, prostate cancer, and colon cancer, with growth inhibition percentages (GI%) ranging from 62.21% to 100.14%. Compounds 10l and 17a were selected for five-dose screening, displaying GI50 values of 1.66-100 μM. Compound 10l induced G0-G1 phase cell cycle arrest in the A549/ATCC cell line, increasing the cell population from 85.41% to 90.86%. Gene expression analysis showed that compound 10l upregulated pro-apoptotic genes p53 and Bax and downregulated the anti-apoptotic gene Bcl-2. Molecular docking studies provided insights into the binding modes of the compounds to the VEGFR-2 enzyme. In conclusion, the pyridazinone-based diarylurea derivatives developed in this study show promise as dual-function antimicrobial and anticancer agents, warranting further investigation.

Design, synthesis, and biological evaluation of novel thiazole derivatives as PI3K/mTOR dual inhibitors.

The development of anticancer drugs targeting both PI3K and mTOR pathways is recognized as a promising cancer therapeutic approach. In the current study, we designed and synthesized seventeen new thiazole compounds to investigate their effect on both PI3K and mTOR as well as their anti-apoptotic activity. All the synthesized thiazoles were investigated for their antiproliferative activity on a panel of 60 different cancer cell lines at the National Cancer Institute. Compounds 3b and 3e were selected for further investigation at five dose concentrations due to their effective growth inhibiting activity. Compounds 3b and 3e were further evaluated for their in vitro inhibitory activities against PI3Kα and mTOR compared to alpelisib and dactolisib, respectively as reference drugs. The inhibitory effect of compound 3b on PI3Kα was similar to alpelisib, but it showed weaker inhibitory activity on mTOR compared to dactolisib. Moreover, compound 3b exhibited significantly higher inhibitory activity compared to compound 3e against both PI3Kα and mTOR. The cell cycle analysis showed that compounds 3b and 3e induced G0-G1 phase cell cycle arrest in the leukemia HL-60(TB) cell line. Meanwhile, they significantly increased the total apoptotic activity which was supported by an increase in the level of caspase-3 in leukemia HL-60(TB) cell lines. Molecular docking experiments provided additional explanation for these results by demonstrating the ability of these derivatives to form a network of key interactions, known to be essential for PI3Kα/mTOR inhibitors. All these experimental results suggested that 3b and 3e are potential PI3Kα/mTOR dual inhibitors and could be considered promising lead compounds for the development of anticancer agents.

Cancer History Avoids the Increase of Senescence Markers in Peripheral Cells of Amnestic Mild Cognitive Impaired Patients.

Epidemiological studies show that having a history of cancer protects from the development of Alzheimer's Disease (AD), and vice versa, AD protects from cancer. The mechanism of this mutual protection is unknown. We have reported that the peripheral blood mononuclear cells (PBMC) of amnestic cognitive impairment (aMCI) and Alzheimer's Disease (AD) patients have increased susceptibility to oxidative cell death compared to control subjects, and from the opposite standpoint a cancer history is associated with increased resistance to oxidative stress cell death in PBMCs, even in those subjects who have cancer history and aMCI (Ca + aMCI). Cellular senescence is a regulator of susceptibility to cell death and has been related to the pathophysiology of AD and cancer. Recently, we showed that cellular senescence markers can be tracked in PBMCs of aMCI patients, so we here investigated whether these senescence markers are dependent on having a history of cancer. Senescence-associated βeta-galactosidase (SA-β-Gal) activity, G0-G1 phase cell-cycle arrest, p16 and p53 were analyzed by flow cytometry; phosphorylated H2A histone family member X (γH2AX) by immunofluorescence; IL-6 and IL-8 mRNA by qPCR; and plasmatic levels by ELISA. Senescence markers that were elevated in PBMCs of aMCI patients, such as SA-β-Gal, Go-G1 arrested cells, IL-6 and IL-8 mRNA expression, and IL-8 plasmatic levels, were decreased in PBMCs of Ca + aMCI patients to levels similar to those of controls or of cancer survivors without cognitive impairment, suggesting that cancer in the past leaves a fingerprint that can be peripherally traceable in PBMC samples. These results support the hypothesis that the senescence process might be involved in the inverse association between cancer and AD.

Inhibitory effect and mechanism of hirsuteine on NCI‑H1299 lung cancer cell lines.

Traditionally, the bark of Uncaria rhynchophylla (UR) has been employed for the treatment of hypertension, cancer, convulsions, haemorrhage, autoimmune disorders and other ailments. The primary aim of the present study was to explore the antiproliferative activity of hirsuteine (HTE) isolated from UR over a range of concentrations in human NSCLC NCI-H1299 cells and to explore the mechanisms underlying its therapeutic efficacy. The effects of HTE on cell viability were examined using Cell Counting Kit-8 (CCK-8) and colony formation assays, while apoptosis was assessed by flow cytometry. Cell cycle progression was additionally evaluated via propidium iodide staining, while reverse transcription-quantitative PCR and western blotting methods were employed to assess the protein levels and genes related to apoptosis and progression of the cell cycle, respectively. NCI-H1299 cell proliferation was markedly suppressed by HTE in a time- and dose-dependent manner. However, clear changes in cell morphology were also induced, resulting in G0-G1 phase cell cycle arrest, which was associated with cyclin E and CDK2 downregulation. HTE additionally induced robust NSCLC NCI-H1299 cell apoptosis, downregulation of Bcl-2 and upregulation of cytoplasmic cytochrome C, Bax, Apaf1, cleaved caspase-3 and cleaved caspase-9, which together drove the observed apoptotic cell death. HTE could effectively suppress human NSCLC NCI-H1299 cell growth by inducing apoptotic death in a dose-dependent fashion in vitro, therefore elucidating the mechanism by which this phytomedicine acts as a potent anticancer compound that warrants study as a treatment for human NSCLC patients.

Senescence Markers in Peripheral Blood Mononuclear Cells in Amnestic Mild Cognitive Impairment and Alzheimer's Disease.

Recent studies suggest that cellular senescence plays a role in Alzheimer’s Disease (AD) pathogenesis. We hypothesize that cellular senescence markers might be tracked in the peripheral tissues of AD patients. Senescence hallmarks, including altered metabolism, cell-cycle arrest, DNA damage response (DDR) and senescence secretory associated phenotype (SASP), were measured in peripheral blood mononuclear cells (PBMCs) of healthy controls (HC), amnestic mild cognitive impairment (aMCI) and AD patients. Senescence-associated βeta-galactosidase (SA-β-Gal) activity, G0-G1 phase cell-cycle arrest, p16 and p53 were analyzed by flow cytometry, while IL-6 and IL-8 mRNA were analyzed by qPCR, and phosphorylated H2A histone family member X (γH2AX) was analyzed by immunofluorescence. Senescent cells in the brain tissue were determined with lipofuscin staining. An increase in the number of senescent cells was observed in the frontal cortex and hippocampus of advanced AD patients. PBMCs of aMCI patients, but not in AD, showed increased SA-β-Gal compared with HCs. aMCI PBMCs also had increased IL-6 and IL8 mRNA expression and number of cells arrested at G0-G1, which were absent in AD. Instead, AD PBMCs had significantly increased p16 and p53 expression and decreased γH2Ax activity compared with HC. This study reports that several markers of cellular senescence can be measured in PBMCs of aMCI and AD patients.

Hirsuteine Inhibits the Proliferation of Human Non-Small Cell Lung Cancer (NSCLC) Cells by Inducing Apoptosis and Cell Cycle Arrest

Background: Hirsuteine is an alkaloid compound that can inhibit the proliferative activity of several cancer cell types in vitro, yet no prior reports have explored its ability to inhibit non-small cell lung cancer (NSCLC) growth. As such, herein, we sought to explore the antiproliferative activity of hirsuteine when used to treat human NSCLC A549 and NC I-H1299 cells across a range of tested concentrations (0–25 μM) and to explore the mechanisms underlying its therapeutic efficacy. Methods: The effects of hirsuteine on cell viability was examined via CCK-8 and colony formation assays, while apoptosis was assessed through Hoechst 33,258 staining and flow cytometry. Cell cycle progression was additionally evaluated via propidium iodide staining, while Western blotting and real-time quantitative polymerase chain reaction (qPCR) method were conducted to assess the levels of proteins and genes associated with apoptosis and cell cycle progression, respectively. Results: Hirsuteine markedly suppressed the proliferation of A549 and NCI-H1299 cells in a dose and time-dependent fashion and induced clear changes in cell morphology, resulting in G0-G1 phase cell cycle arrest that was related to the downregulation of Cyclin E and CDK2. Hirsuteine additionally induced robust apoptosis of A549 and NCI-H1299 cells and Bcl-2 downregulation together with the upregulation of Bax, Apaf1, cytoplasmic cytochrome C, cleaved caspase-3 and cleaved caspase-9, together driving this apoptotic cell death. Conclusion: Hirsuteine can effectively suppress the growth of human NSCLC A549 and NCI-H1299 cells and induce apoptotic death in a dose-dependent fashion in vitro , emphasizing the promising of this alkaloid compound as a potent anticancer treatment that warrants study as a treatment for human NSCLC patients.

Preclinical Evaluation of Gilteritinib on NPM1-ALK-Driven Anaplastic Large Cell Lymphoma Cells.

Anaplastic large cell lymphoma (ALCL) is an aggressive type of non-Hodgkin lymphoma. More than three-fourths of anaplastic lymphoma kinase (ALK)-positive ALCL cases express the nucleophosmin 1 (NPM1)-ALK fusion gene as a result of t(2;5) chromosomal translocation. The homodimerization of NPM1-ALK fusion protein mediates constitutive activation of the chimeric tyrosine kinase activity and downstream signaling pathways responsible for lymphoma cell proliferation and survival. Gilteritinib is a tyrosine kinase inhibitor recently approved by the FDA for the treatment of FMS-like tyrosine kinase mutation-positive acute myeloid leukemia. In this study, we demonstrate for the first time gilteritinib-mediated growth inhibitory effects on NPM1-ALK-driven ALCL cells. We utilized a total of five ALCL model cell lines, including both human and murine. Gilteritinib treatment inhibits NPM1-ALK fusion kinase phosphorylation and downstream signaling, resulting in induced apoptosis. Gilteritinib-mediated apoptosis was associated with caspase 3/9, PARP cleavage, the increased expression of proapoptotic protein BAD, and decreased expression of antiapoptotic proteins, survivin and MCL-1. We also found downregulation of fusion kinase activity resulted in decreased c-Myc protein levels. Furthermore, cell-cycle analysis indicated gilteritinib induced G0-G1-phase cell-cycle arrest and reduced CD30 expression. In summary, our preclinical studies explored the novel therapeutic potential of gilteritinib in the treatment of ALCL cells expressing NPM1-ALK and potentially in other ALK or ALK fusion-driven hematologic or solid malignancies. IMPLICATIONS: Our preclinical results explore the use of gilteritinib for the treatment of NPM1-ALK-driven ALCL cells and pave a path for developing future clinical trials. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/5/913/F1.large.jpg.

Ribociclib (LEE011) suppresses cell proliferation and induces apoptosis of MDA-MB-231 by inhibiting CDK4/6-cyclin D-Rb-E2F pathway

Triple-negative breast cancer (TNBC) stands for a refractory subtype, which predicts poor prognosis and has no effective therapies yet for improving it. Given the restrictions of traditional treatments, novel therapeutic strategies need excavating to alleviate the intrinsic or acquired resistance. Ribociclib, a selective CDK4/6 inhibitor, has successfully prevented cancers from deteriorating by intervening the CDK4/6-cyclin D-Rb-E2F pathway, especially for estrogen receptor-positive (ER +) breast cancer. However, there still remains limited accessibility referring to TNBC. Performing experiments on MDA-MB-231 cells, we found that LEE011 could suppress cell proliferation, and this suppression tended to be dose-dependently. Western blotting analysis presented significant decrease with the expression of CDK4/6 after LEE011 treated, and other proteins associated with this axis such as cyclin D1, p-Rb, Rb, E2F1 showed aberrant changes. Moreover, LEE011 induced G0–G1 phase cell cycle arrest, promoted cell apoptosis, and reduced cell migration in vitro. In addition, tumor growth was remarkably impeded without obvious side-effects in MDA-MB-231 xenograft models. Our research has identified that LEE011 was not completely invalid for MDA-MB-231. Considering its pivotal status in TNBC, the CDK4/6-cyclin D-Rb-E2F pathway informed us the possibility and practicality of Ribociclib (LEE011) as pharmacological intervention, but challenges warrant further validation in prospective studies.

Cannabidiol Induces Cell Cycle Arrest and Cell Apoptosis in Human Gastric Cancer SGC-7901 Cells.

The main chemical component of cannabis, cannabidiol (CBD), has been shown to have antitumor properties. The present study examined the in vitro effects of CBD on human gastric cancer SGC-7901 cells. We found that CBD significantly inhibited the proliferation and colony formation of SGC-7901 cells. Further investigation showed that CBD significantly upregulated ataxia telangiectasia-mutated gene (ATM) and p53 protein expression and downregulated p21 protein expression in SGC-7901 cells, which subsequently inhibited the levels of CDK2 and cyclin E, thereby resulting in cell cycle arrest at the G0–G1 phase. In addition, CBD significantly increased Bax expression levels, decreased Bcl-2 expression levels and mitochondrial membrane potential, and then upregulated the levels of cleaved caspase-3 and cleaved caspase-9, thereby inducing apoptosis in SGC-7901 cells. Finally, we found that intracellular reactive oxygen species (ROS) increased after CBD treatment. These results indicated that CBD could induce G0–G1 phase cell cycle arrest and apoptosis by increasing ROS production, leading to the inhibition of SGC-7901 cell proliferation, thereby suggesting that CBD may have therapeutic effects on gastric cancer.

Heterogeneous expression and biological function of SOX18 in osteosaroma.

Osteosaroma (OS) is a primary bone malignancy and is associated with high morbidity. Sex determining region Y-box 18 (SOX18) is identified overexpressed in OS. However, the molecular mechanism underlying the biological function of SOX18 in OS is still unclear. The aim of the current study was to determine the SOX18 expression in patients with OS and its effect on tumor cell malignant phenotypes. Our results showed that SOX18 was overexpressed in OS patients from both E-MEXP-3628 database and independent samples from our hospital and in OS cell lines. SOX18 silencing significantly induced G0-G1 phase cell cycle arrest and apoptosis and inhibited U-2OS cell migration and invasion and cell growth both in vitro and in vivo. However, SOX18 overexpression remarkably promoted 143B cell proliferation, migration and invasion and inhibited cell cycle arrest and apoptosis. The protein expression levels of p53, p21, Bax, Bcl-2, and Caspase-3 were also regulated by SOX18. Moreover, SOX18 was found negative correlated with the expression of HERC1, HER2, HERC3, HERC4, HERC5, and HERC6 in OS patients and in OS cells, with the most significant correlation detected in HERC2 expression, which was following found interacted with SOX18 in OS cells. Taken together, our results suggest that SOX18 is overexpressed in OS and plays an important role in proliferation, apoptosis, migration and invasion of OS cells, and may provide a novel and promising thera-peutic strategy for OS.

MiR-6883 Family miRNAs Target CDK4/6 to Induce G1 Phase Cell-Cycle Arrest in Colon Cancer Cells.

CDK4/6 targeting is a promising therapeutic strategy under development for various tumor types. In this study, we used computational methods and The Cancer Genome Atlas dataset analysis to identify novel miRNAs that target CDK4/6 and exhibit potential for therapeutic development in colorectal cancer. The 3'UTR of CDK4/6 mRNAs are targeted by a family of miRNAs, which includes miR-6883-5p, miR-149*, miR-6785-5p, and miR-4728-5p. Ectopic expression of miR-6883-5p or miR-149* downregulated CDK4 and CDK6 levels in human colorectal cancer cells. RNA-seq analysis revealed an inverse relationship between the expression of CDK4/6 and miR-149* and intronic miRNA-6883-5p encoding the clock gene PER1 in colorectal cancer patient samples. Restoring expression of miR-6883-5p and miR-149* blocked cell growth leading to G0-G1 phase cell-cycle arrest and apoptosis in colorectal cancer cells. CDK4/6 targeting by miR-6883-5p and miR-149* could only partially explain the observed antiproliferative effects. Notably, both miRNAs synergized with the frontline colorectal cancer chemotherapy drug irinotecan. Further, they resensitized mutant p53-expressing cell lines resistant to 5-fluorouracil. Taken together, our results established the foundations of a candidate miRNA-based theranostic strategy to improve colorectal cancer management. Cancer Res; 77(24); 6902-13. ©2017 AACR.

Inhibition of mTORC2 Induces Cell-Cycle Arrest and Enhances the Cytotoxicity of Doxorubicin by Suppressing MDR1 Expression in HCC Cells.

mTOR is aberrantly activated in hepatocellular carcinoma (HCC) and plays pivotal roles in tumorigenesis and chemoresistance. Rapamycin has been reported to exert antitumor activity in HCC and sensitizes HCC cells to cytotoxic agents. However, due to feedback activation of AKT after mTOR complex 1 (mTORC1) inhibition, simultaneous targeting of mTORC1/2 may be more effective. In this study, we examined the interaction between the dual mTORC1/2 inhibitor OSI-027 and doxorubicin in vitro and in vivo. OSI-027 was found to reduce phosphorylation of both mTORC1 and mTORC2 substrates, including 4E-BP1, p70S6K, and AKT (Ser473), and inhibit HCC cell proliferation. Similar to OSI-027 treatment, knockdown of mTORC2 induced G0-G1 phase cell-cycle arrest. In contrast, rapamycin or knockdown of mTORC1 increased phosphorylation of AKT (Ser473), yet had little antiproliferative effect. Notably, OSI-027 synergized with doxorubicin for the antiproliferative efficacy in a manner dependent of MDR1 expression in HCC cells. The synergistic antitumor effect of OSI-027 and doxorubicin was also observed in a HCC xenograft mouse model. Moreover, AKT was required for OSI-027-induced cell-cycle arrest and downregulation of MDR1. Our findings provide a rationale for dual mTORC1/mTORC2 inhibitors, such as OSI-027, as monotherapy or in combination with cytotoxic agents to treat HCC. Mol Cancer Ther; 14(8); 1805-15. ©2015 AACR.

Low expression of ERK signaling pathway affecting proliferation, cell cycle arrest and apoptosis of human gastric HGC-27 cells line

This study was carried out for the first time to examine the potential role and the underlying mechanisms of Lycopene in the gastric cancer HGC-27 cells. HGC-27 cells were seeded onto heat-sterilized coverslips in six-well plates and exposed to Lycopene (5, 10, 20, 30 and 40 μmol/L) for periods of 72 h at 37 °C. Results showed that Lycopene (5, 10, 20, 30 and 40 μmol/L) dose-dependently increased NBT positive rate and decreased lactate dehydrogenase activity in HGC-27 cells. In addition, Lycopene (5, 10, 20, 30 and 40 μmol/L) inhibited proliferation and induced G0-G1 phase cell cycle arrest in HGC-27 cells. Western blot and FQRT-PCR analysis showed that Lycopene decreased pERK and extracellular signal-regulated kinase (ERK) protein and mRNA expression in a dose-dependent manner. These findings demonstrate that Lycopene inhibited gastric cancer HGC-27 cells growth and stimulated its apoptosis via the suppressing ERK signaling pathway.

Abstract 4793: NOSH-aspirin inhibits breast cancer cell growth: an effect modulated through reactive oxygen species and independent of the ER status.

Abstract Introduction: We recently reported the synthesis and characterization of NOSH-aspirin a highly potent hybrid; that releases both nitric oxide (NO) and hydrogen sulfide (H2S) two important signalling molecules of physiological relevance. The present study was undertaken to unravel some of the underlying mechanisms of its action. Methods: Cell lines: MCF-7 (ER+), MDA-MB-231 (ER-, PR-, does not over express Her2), HMEpC, normal human mammary epithelial; Cell growth: MTT; Cell cycle phase distribution: Apoptosis and cell cycle: Flow cytometry; Proliferation: PCNA; ROS: measured hydrogen peroxide and super oxide by flow cytometry using DCFDA and DHE dyes. Xenografts: NuNu mice (N=5/group) implanted with MCF-7 and MDA-MB 231, after 10 days randomly divided animals and gavaged daily with NOSH-ASA (100 mg/kg body weight) or vehicle. Tumor volume and animal weight were recorded every 3 days. After 4 weeks of treatment, mice were sacrificed, tumors excised, weighed, and fixed in 10% buffered formalin. Results: NOSH-aspirin's IC50 in nM at 24h for cell growth inhibition were MCF-7 (285±20), MDA-MB-231 (98±9), HMEpC (20,000±3,000); aspirin's IC50 in all cell lines was greater than 5,000,000 nM at 24h. Cell proliferation at 2xIC50 was decreased 31±4 % in ER+ cells and 27.8 2% in ER- cells. This was accompanied by a G0-G1 phase cell cycle arrest (59.5% at IC50 for ER+ cells and 66.3% at IC50 for ER- cells). NOSH-aspirin at the doses studied, did not cause appreciable apoptosis at 24hr, at 2xIC50 the values being 32.7±3% in ER(+) and 24±2% in ER(-) cells. These results are in line with our data showing that in PC9 lung cancer cells stably expressing cytochrome c-GFP (used for mitochondrial cytochrome c release) NOSH-aspirin caused partial release of cytochrome c up to 3 hours when followed in real -time by fluorescence microscopy and image analysis. NOSH-ASA increased intracellular H2O2 and superoxide anions. Pretreatment of cells with N-acetylcysteine, blocked these. Xenografts: NOSH-aspirin had no effect on the weight of the mice and there were no overt signs of toxicity. Tumor volume was reduced as a function of treatment time. The growth rate of ER(-) xenografts was significantly greater than that of ER(+) ones and NOSH-aspirin had a greater effect on the ER(-) vs ER(+) xenografts. Tumor mass for each group were, ER(+): 0.46±0.056g untreated and 0.21±0.035g treated, (55% reduction, P=0.022), ER(-): 1.2±0.33g untreated and 0.11±0.058g treated (91% reduction, P=0.006). NOSH-aspirin inhibited growth of these cancer cell xenografts as a result of reduced proliferation (decreased PCNA expression), and induction apoptosis (increased number of TUNEL positive cells), and induction of ROS. Conclusions: NOSH-aspirin preferentially affects cancer cells and has potent anti-cancer properties. It targets parameters important in determining cellular mass and merits further evaluation. Citation Format: Diandra E. Nesbitt, Mitali Chattopadhyay, Federica Vannini, Thuy-Tien C. Le, Ravinder Kodela, Niharika Nath, Khosrow Kashfi. NOSH-aspirin inhibits breast cancer cell growth: an effect modulated through reactive oxygen species and independent of the ER status. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4793. doi:10.1158/1538-7445.AM2013-4793 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

4-O-methylhonokiol inhibits colon tumor growth via p21-mediated suppression of NF-κB activity

Biphenolic components in the Magnolia family have shown several pharmacological activities such as antitumor effects. This study investigated the effects of 4-O-methylhonokiol (MH), a constituent of Magnolia officinalis, on human colon cancer cell growth and its action mechanism. 4-O-methylhonokiol (0–30 μM) decreased constitutive activated nuclear factor (NF)-κB DNA binding activity and inhibited growth of human colon (SW620 and HCT116) cancer cells. It also caused G0–G1 phase cell cycle arrest followed by an induction of apoptotic cell death. However, knockdown with small interfering RNA (siRNA) of p21 or transfection with cyclin D1/Cdk4 binding site-mutated p21 abrogated MH-induced cell growth inhibition, inhibition of NF-κB activity as well as expression of cyclin D1 and Cdk4. Conversely, inhibition of NF-κB with specific inhibitor or siRNA augmented MH-induced apoptotic cell death. 4-O-methylhonokiol inhibited tumor growth, NF-κB activity and expression of antiapoptotic proteins; however, it increased the expression of apoptotic proteins as well as p21 in xenograft nude mice bearing SW620 cancer cells. The present study reveals that MH causes p21-mediated human colon cancer cell growth inhibition through suppression of NF-κB and indicates that this compound by itself or in combination with other anticancer agents could be useful for the treatment of cancer.

Garcinol Inhibits Cell Proliferation and Promotes Apoptosis in Pancreatic Adenocarcinoma Cells

Garcinol, or polyisoprenylated benzophenone, isolated from the rind of fruiting bodies of Garcinia indica, has been used in traditional medicine for its potential antiinflammatory and antioxidant properties. The objective of this study was to investigate the effect of garcinol on pancreatic cancer (PaCa) cell viability and proliferation. For this, 2 human PaCa cell lines, BxPC-3 and Panc-1, with wild and mutant k-ras, respectively, were treated with garcinol (0–40 μM). Garcinol significantly (P < 0.05) inhibited cell growth (trypan blue exclusion) by induction of apoptosis in a dose- and time-dependent manner. Flow cytometric analysis revealed G0–G1 phase cell cycle arrest in both cell lines. The molecular mechanism of garcinol's action on PaCa cells was investigated by targeting signaling moieties involved in apoptosis (X-IAP, cIAP, caspase-3, 9, and PARP cleavage), transcription factor NF-κB, believed to contribute toward a chemoresistance phenotype in pancreatic tumors, and molecules associated with neovascularization and metastasis (MMP-9, VEGF, IL-8, and PGE2). Garcinol significantly (P < 0.05) augmented antiproliferative, proapoptotic, antimetastatic, and antiangiogenic effects in both PaCa cell types relative to untreated cells. These effects were more pronounced in Panc-1. This is the first report on the therapeutically relevant effect of garcinol in PaCa. Further studies are warranted, based on our findings.

Dual Inhibition of Class IA Phosphatidylinositol 3-Kinase and Mammalian Target of Rapamycin as a New Therapeutic Option for T-Cell Acute Lymphoblastic Leukemia

Recent investigations have documented that constitutively activated phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling is a common feature of T-cell acute lymphoblastic leukemia (T-ALL), where it strongly influences growth and survival. These findings lend compelling weight for the application of PI3K/Akt/mTOR inhibitors in T-ALL. However, our knowledge of PI3K/Akt/mTOR signaling in T-ALL is limited and it is not clear whether it could be an effective target for innovative therapeutic strategies. Here, we have analyzed the therapeutic potential of the dual PI3K/mTOR inhibitor PI-103, a small synthetic molecule of the pyridofuropyrimidine class, on both T-ALL cell lines and patient samples, which displayed constitutive activation of PI3K/Akt/mTOR signaling. PI-103 inhibited the growth of T-ALL cells, including 170-kDa P-glycoprotein overexpressing cells. PI-103 cytotoxicity was independent of p53 gene status. PI-103 was more potent than inhibitors that are selective only for PI3K (Wortmannin, LY294002) or for mTOR (rapamycin). PI-103 induced G(0)-G(1) phase cell cycle arrest and apoptosis, which was characterized by activation of caspase-3 and caspase-9. PI-103 caused Akt dephosphorylation, accompanied by dephosphorylation of the Akt downstream target, glycogen synthase kinase-3beta. Also, mTOR downstream targets were dephosphorylated in response to PI-103, including p70S6 kinase, ribosomal S6 protein, and 4E-BP1. PI-103 strongly synergized with vincristine. These findings indicate that multitargeted therapy toward PI3K and mTOR alone or with existing drugs may serve as an efficient treatment toward T-ALL cells, which require up-regulation of PI3K/Akt/mTOR signaling for their survival and growth.

Protein Kinase D3 (PKD3) Contributes to Prostate Cancer Cell Growth and Survival Through a PKCε/PKD3 Pathway Downstream of Akt and ERK 1/2

Protein kinase D (PKD) is a family of novel diacylglycerol/phorbol ester targets that regulate many important cellular functions including cell growth and survival. We now provide experimental evidence to indicate that PKD3 contributes to prostate cancer cell growth and survival. Expression of PKD3 as well as PKD1 was significantly higher in human prostate tumors compared with normal tissues as revealed by immunohistochemistry. Moreover, PKD3 exhibited a marked increase in nuclear localization in tumor tissues, which correlated with tumor grade. Isoforms of PKD were differentially expressed and localized between normal and human prostate cancer cells. Increased protein expression and nuclear accumulation of PKD3 were observed in the more aggressive androgen-independent PC3 and DU145 cells compared with the less aggressive androgen-dependent LNCaP cells. Overexpression of wild-type PKD3 in LNCaP cells blocked phorbol 12-myristate 13-acetate (PMA)-induced apoptosis in association with inhibition of PMA-induced down-regulation of Akt activity, and prolonged extracellular signal-regulated kinase (ERK)1/2 activation. Overexpression of wild-type PKD3 also promoted S phase entry, whereas depletion of endogenous PKD3 resulted in G(0)-G(1) phase cell cycle arrest and inhibition of PC3 cell proliferation. In PC3 and DU145 cells, PKCepsilon regulated PKD3 kinase activity and nuclear localization. Moreover, ectopical expression of PKD3 increased, whereas depletion of endogenous PKD3 reduced basal Akt and ERK1/2 activities. Further analysis showed that up-regulation of Akt activity induced by PKD3 required phosphatidylinositol-3-OH kinase and p38. In summary, our data indicate that PKD3 contributes to growth and survival of prostate cancer cells and may represent a novel therapeutic target for prostate cancer.

Honokiol causes G0-G1 phase cell cycle arrest in human prostate cancer cells in association with suppression of retinoblastoma protein level/phosphorylation and inhibition of E2F1 transcriptional activity

The present study was undertaken to gain insights into the mechanism of cell cycle arrest caused by honokiol, a constituent of oriental herb Magnolia officinalis. The honokiol treatment decreased the viability of PC-3 and LNCaP human prostate cancer cells in a concentration- and time-dependent manner, which correlated with G0-G1 phase cell cycle arrest. The honokiol-mediated cell cycle arrest was associated with a decrease in protein levels of cyclin D1, cyclin-dependent kinase 4 (Cdk4), Cdk6, and/or cyclin E and suppression of complex formation between cyclin D1 and Cdk4 as revealed by immunoprecipitation using anti-cyclin D1 antibody followed by immunoblotting for Cdk4 protein. The honokiol-treated PC-3 and LNCaP cells exhibited a marked decrease in the levels of total and phosphorylated retinoblastoma protein (Rb), which correlated with the suppression of transcriptional activity of E2F1. Exposure of PC-3 and LNCaP cells to honokiol resulted in the induction of p21 (PC-3 and LNCaP) and p53 protein expression (LNCaP). However, small interfering RNA (siRNA)-mediated knockdown of either p21 (PC-3 and LNCaP) or p53 (LNCaP) protein failed to confer any protection against honokiol-induced cell cycle arrest. The honokiol treatment caused the generation of reactive oxygen species (ROS), and the cell cycle arrest caused by honokiol was partially but significantly attenuated in the presence of antioxidant N-acetylcysteine. In conclusion, the present study reveals that the honokiol-mediated G0-G1 phase cell cycle arrest in human prostate cancer cells is associated with the suppression of protein level/phosphorylation of Rb leading to inhibition of transcriptional activity of E2F1.

Sanguinarine induces apoptosis of human pancreatic carcinoma AsPC-1 and BxPC-3 cells via modulations in Bcl-2 family proteins

Pancreatic cancer is associated with low responsiveness to conventional chemotherapies and its incidence nearly equals its death rate. This warrants the development of novel mechanism-based approaches for the management of pancreatic cancer. This study was designed to determine the potential of sanguinarine, a plant alkaloid known to possess strong antimicrobial, anti-inflammatory, and antioxidant activities, against human pancreatic carcinoma cells. Employing human pancreatic carcinoma AsPC-1 and BxPC-3 cells, we specifically evaluated the pro-apoptotic and cell cycle deregulatory effects of sanguinarine and evaluated the involvement of Bcl-2 family proteins and p53 as the mechanism of the biological effects of sanguinarine. Our data demonstrated that sanguinarine (at low concentrations of 0.1–10 μM; for 24 h) treatment to AsPC-1 and BxPC-3 cells resulted in a dose dependent (i) inhibition of viability and growth, (ii) colony formation ability, (iii) induction of apoptosis, and (iv) G0-G1 phase cell cycle arrest. Further, sanguinarine-treatment to AsPC-1 and BxPC-3 cells resulted in a dose dependent (i) increase in pro-apoptotic Bax, Bid and Bak proteins; (ii) decrease in anti-apoptotic Bcl-2 and Bcl-X L proteins; and (iii) decrease in p53 with an increase in its phosphorylation. Based on our study, we suggest that sanguinarine may be developed as an agent for the management of pancreatic cancer. Indeed, more in depth studies both in vitro as well as in vivo in appropriate relevant animal models are needed to strengthen this suggestion.