R A Lubet

National Cancer Institute (USA), Maryland, United States

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Publications (365)1560.51 Total impact

  • Qi Zhang, Jing Pan, Ronald A. Lubet, Yian Wang, Ming You
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    ABSTRACT: Insulin-like growth factor-1 receptor (IGF-1R) is a transmembrane heterotetramer that is activated by Insulin-like growth factor 1 and is crucial for tumor transformation and survival of malignant cells. Importantly, IGF-1R overexpression has been reported in many different cancers, implicating this receptor as a potential target for anticancer therapy. Picropodophyllin (PPP) is a potent inhibitor of IGF-1R and has antitumor efficacy in several cancer types. However, the chemopreventive effect of PPP in lung tumorigenesis has not been investigated. In this study, we investigated the chemopreventive activity of PPP in a mouse lung tumor model. Benzo(a)pyrene was used to induce lung tumors, and PPP was given by nasal inhalation to female A/J mice. Lung tumorigenesis was assessed by tumor multiplicity and tumor load. PPP significantly decreased tumor multiplicity and tumor load. Tumor multiplicity and load were decreased by 52% and 78% respectively by 4 mg/ml aerosolized PPP. Pharmacokinetics analysis showed good bioavailability of PPP in lung and plasma. Treatment with PPP increased staining for cleaved caspase-3 and decreased Ki-67 in lung tumors, suggesting that the lung tumor inhibitory effects of PPP were partially through inhibition of proliferation and induction of apoptosis. In human lung cancer cell lines, PPP inhibited cell proliferation, and also inhibited phosphorylation of IGF-1R downstream targets, AKT and MAPK, ultimately resulting in increased apoptosis. PPP also reduced cell invasion in lung cancer cell lines. In view of our data, PPP merits further investigation as a promising chemopreventive agent for human lung cancer. © 2014 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 08/2014; · 4.27 Impact Factor
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    ABSTRACT: Green tea is a promising chemopreventive agent for lung cancer. Multiple signaling events have been reported, however, the relative importance of these mechanisms in mediating the chemopreventive function of green tea is unclear. In the present study, to examine the involvement of AP-1 in green tea polyphenols induced tumor inhibition, human NSCLC cell line H1299 and mouse SPON 10 cells were identified as AP-1 dependent, as these two lines exhibit high constitutive AP-1 activity, and when TAM67 expression was induced with doxycycline, cell growth was inhibited and correlated with suppressed AP-1 activity. RNA-seq was used to determine the global transcriptional effects of AP-1 inhibition and also uncover the possible involvement of AP-1 in tea polyphenols induced chemoprevention. TAM67 mediated changes in gene expression were identified, and within down-regulated genes, AP-1 was identified as a key transcription regulator. RNA-seq analysis revealed that Polyphenon E-treated cells shared 293 commonly down-regulated genes within TAM67 expressing H1299 cells, and by analysis of limited Chip-seq data, over 10% of the down-regulated genes contain a direct AP-1 binding site, indicating that Polyphenon E elicits chemopreventive activity by regulating AP-1 target genes. Conditional TAM67 expressing transgenic mice and NSCLC cell lines were used to further confirm that the chemopreventive activity of green tea is AP-1 dependent. Polyphenon E lost its chempreventive function both in vitro and in vivo when AP-1 was inhibited, indicating that AP-1 inhibition is a major pathway through which green tea exhibits chemopreventive effects. © 2013 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 01/2014; 53(1):19-29. · 4.27 Impact Factor
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    ABSTRACT: Urinary bladder cancer prevention studies were performed with the nonsteroidal anti-inflammatory drugs (NSAIDs) naproxen (standard NSAID with a good cardiovascular profile), sulindac, and their nitric oxide (NO) derivatives. Additionally, the effects of the ornithine decarboxylase inhibitor, difluoromethylornithine (DFMO), alone or combined with a suboptimal dose of naproxen or sulindac was examined. Agents were evaluated at their human equivalent doses (HEDs), as well as at lower doses. In the hydroxybutyl(butyl)nitrosamine (OH-BBN) model of urinary bladder cancer, naproxen (400 or 75 ppm) and sulindac (400 ppm) reduced the incidence of large bladder cancers by 82, 68 and 44%, respectively, when the agents were initially given 3 months after the final dose of the carcinogen; microscopic cancers already existed. NO-naproxen was highly effective, while NO-sulindac was inactive. To further compare naproxen and NO-naproxen, we examined their effects on gene expression in rat livers following a 7 day exposure. Limited, but similar, gene expression changes in the liver were induced by both agents, implying that the primary effects of both are mediated by the parent NSAID. When agents were initiated 2 weeks after the last administration of OH-BBN, DFMO at 1000 ppm had limited activity, a low dose of naproxen (75 ppm) and sulindac (150 ppm) were highly and marginally effective. Combining DFMO with suboptimal doses of naproxen had minimal effects whereas the combination of DMFO and sulindac was more active than either agent alone. Thus, naproxen and NO-naproxen were highly effective, while sulindac was moderately effective in the OH-BBN model at their HEDs.
    Cancer Prevention Research 12/2013; · 4.89 Impact Factor
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    ABSTRACT: Naproxen ((S)-6-methoxy-α-methyl-2-naphthaleneacetic acid) is a potent nonsteroidal anti-inflammatory drug that inhibits both COX-1 and COX-2 and is widely used as an over-the-counter medication. Naproxen exhibits analgesic, anti-pyretic, and anti-inflammatory activities. Naproxen, as well as other NSAIDS, has been reported to be effective in the prevention of urinary bladder cancer in rodents. However, potential targets other than the COX isozymes have not been reported. We examined potential additional targets in urinary bladder cancer cells and in rat bladder cancers. Computer kinase profiling results suggested that phosphatidylinositol 3-kinase (PI3-K) is a potential target for naproxen. In vitro kinase assay data revealed that naproxen interacts with PI3-K and inhibits its kinase activity. Pull-down binding assay data confirmed that PI3-K directly binds with naproxen in vitro and ex vivo. Western blot data showed that naproxen decreased phosphorylation of Akt, and subsequently decreased Akt signaling in UM-UC-5 and UMUC-14 urinary bladder cancer cells. Furthermore, naproxen suppressed anchorage-independent cell growth and decreased cell viability by targeting PI3-K in both cell lines. Naproxen caused an accumulation of cells at the G1 phase mediated through CDK4, cyclin D1 and p21. Moreover, naproxen induced significant apoptosis, accompanied with increased levels of cleaved caspase 3, caspase 7, and poly (ADP-ribose) polymerase (PARP) in both cell types. Naproxen-induced cell death was mainly due to apoptosis in which a prominent down-regulation of Bcl-2 and up-regulation of Bax were involved. Naproxen also caused apoptosis and inhibited Akt phosphorylation in rat urinary bladder cancers induced by N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN).
    Cancer Prevention Research 12/2013; · 4.89 Impact Factor
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    ABSTRACT: Recent clinical trials raised concerns regarding the cardiovascular toxicity of selective cyclooxygenase-2 (COX-2) inhibitors and COX-1 is now being reconsidered as a target for chemoprevention. Our aims were to determine whether selective COX-1 inhibition could delay or prevent cancer development and also clarify the underlying mechanisms. Data clearly showed that COX-1 was required for maintenance of malignant characteristics of colon cancer cells or tumor promoter-induced transformation of pre-neoplastic cells. We also successfully applied a ligand docking computational method to identify a novel selective COX-1 inhibitor, 6-C-(E-phenylethenyl)-naringenin (designated herein as 6CEPN). 6CEPN could bind to COX-1 and specifically inhibited its activity both in vitro and ex vivo. In colorectal cancer cells, it potently suppressed anchorage-independent growth by inhibiting COX-1 activity. 6CEPN also effectively suppressed tumor growth in a 28-day colon cancer xenograft model without any obvious systemic toxicity. Taken together, COX-1 plays a critical role in human colorectal carcinogenesis, and this specific COX-1 inhibitor merits further investigation as a potential preventive agent against colorectal cancer.
    Cancer Research 11/2013; · 9.28 Impact Factor
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    ABSTRACT: Aromatase inhibitors(AIs)are effective in therapy/prevention of ER+ breast cancers. Rats bearing methylnitrosourea(MNU)-induced ER+ mammary cancers were treated with the AI vorozole (1.25 mg/kg BW/day) for 5 days. RNA expression showed 162 down-regulated and 180 up-regulated (p < 0.05 and fold change >1.5) genes. Genes modulated by vorozole were compared with published data from four clinical neoadjuvant trials employing AIs (anastrozole or letrozole). More than thirty genes and multiple pathways exhibited synchronous changes in animal and human data sets. Cell cycle genes related to chromosome condensation in prometaphase (APC pathway, including Aurora-A kinase, BUBR1B, TOP2, Cyclin A, Cyclin B CDC2 and TPX-2) were down-regulated in animal and human studies reflecting the strong anti-proliferative effects of AIs. Comparisons of rat arrays with a cell culture study where estrogen was removed from MCF-7 cells showed decreased expression of E2F1-modulated genes as a major altered pathway. Alterations of the cell cycle and E2F related genes were confirmed in a large independent set of human samples (81 pairs baseline and 2 weeks anastrozole treatment). Decreases in proliferation related genes were confirmed at the protein level for Cyclin A2, BuRB1, cdc2, Pttg and TPX-2. Interestingly, the proteins down-regulated in tumors were similarly down-regulated in vorozole treated normal rat mammary epithelium. Finally, decreased expression of known estrogen responsive genes (including TFF 1,3, progesterone receptor, etc.) were decreased in the animal model. These studies demonstrate that gene expression changes (pathways and individual genes) are similar in humans and the rat model.
    Cancer Prevention Research 09/2013; · 4.89 Impact Factor
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    ABSTRACT: The UVB component of sunlight, which causes DNA damage and inflammation, is the major cause of nonmelanoma skin cancer (NMSC), the most prevalent of all cancers. Nonsteroidal anti-inflammatory drugs (NSAIDs) and coxibs have been shown to be effective chemoprevention agents in multiple preclinical trials, including NMSC, colon and urinary bladder cancer. NSAIDs, however, cause gastrointestinal irritation, which led to the recent development of nitric oxide (NO) derivatives that may partially ameliorate this toxicity. This study compared the efficacy of several NSAIDs and NO-NSAIDs on UV-induced NMSC in SKH-1 hairless mice and determined whether various short-term biomarkers were predictive of long-term tumor outcome with these agents. Naproxen at 100 (p>.05) and 400 ppm (p<.01) in the diet reduced tumor multiplicity by 26 and 63% respectively. The NO-naproxen at slightly lower molar doses shows similar activities. Aspirin at 60 or 750 ppm in the diet reduced tumor multiplicity by 19 and 50%; while the equivalent doses (108 and 1350 ppm) were slightly less effective. Sulindac at 25 and 150 ppm in the diet doses far below the Human Equivalent Dose, was the most potent NSAID with reductions of 50 and 94% respectively. In testing short-term biomarkers we found that agents that reduce UV-induced prostaglandin E2 synthesis and/or inhibit UV-induced keratinocyte proliferation yielded long-term tumor efficacy.
    Cancer Prevention Research 05/2013; · 4.89 Impact Factor
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    ABSTRACT: The phosphatidylinositol 3-kinase (PI3-K)/Akt and mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in cell survival and proliferation and is often aberrantly activated in many types of cancer. The mTOR kinase protein, one of the key molecules in this pathway, has been shown to be an important target for cancer therapy. In the present study, a ligand docking method was used to screen for novel scaffold mTOR inhibitors. Sixty thousand compounds in the Natural Product Database (NPD) were screened against the mTOR homologous structure and 13 commercially available compounds listed in the top-ranked 100 compounds were selected for further examination. Compound (E)-3-(4-(benzo[d][1,3]dioxol-5-yl)-2-oxobut-3-en-1-yl)- 3-hydroxyindolin-2-one; designated herein as 3HOI-BA-01) was then selected for further study of its antitumor activity. An in vitro study demonstrated that 3HOI-BA-01 inhibited mTOR kinase activity in a dose-dependent manner by directly binding with mTOR. In a panel of NSCLC cells, the compound also attenuated mTOR downstream signaling, including the phosphorylation of p70S6K, S6, and Akt, resulting in G1 cell cycle arrest and growth inhibition. Results of an in vivo study demonstrated that i.p. injection of 3HOI-BA-01 in A549 lung tumor-bearing mice effectively suppressed cancer growth without affecting the body weight of the mice. The expression of downstream signaling molecules in the mTOR pathway in tumor tissues was also reduced after 3HOI-BA-01 treatment. Taken together, we identified 3HOI-BA-01 as a novel and effective mTOR inhibitor.
    Molecular Cancer Therapeutics 03/2013; · 5.60 Impact Factor
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    ABSTRACT: EGFR inhibitors are employed in therapy of lung and pancreatic cancers, and effectively prevent cancers in multiple animal models. Although daily dosing with erlotinib is effective, weekly dosing may reduce toxicity and have advantages, particularly for prevention. We tested alternative dosing regimens for preventive/therapeutic efficacy in a rat mammary cancer model. For prevention, erlotinib was administered by gavage beginning 5 days after MNU. For therapy and biomarker studies, rats with palpable mammary cancers were treated for six weeks or for 6 days, respectively. Prevention. Experiment A. Erlotinib (6 mg/Kg BW/day, i.g.): daily (7x/week); one day on/one day off; and two days on/two days off. All regimens decreased tumor incidence, increased tumor latency, and decreased cancer multiplicity vs controls (P<.01). However, intermittent dosing was less effective than daily dosing (P<.05). Experiment B. Erlotinib (6 mg/kg BW/day) daily or two days on/two days off; or 1x/week at 42 mg/kg BW. All regimens reduced cancer incidence and multiplicity vs controls (P<.01). Interestingly, daily and weekly dosing were equally effective (P>0.5). Experiment C. Erlotinib administered at 42 or 21 mg/kg BW, 1x/week, decreased tumor incidence and multiplicity (P<.01). Pharmacokinetics. Erlotinib had a serum half-life of ≤8 hours, and weekly treatment yielded effective serum levels for <48 hours. Therapy. Daily or weekly treatment of cancer bearing rats reduced mammary tumor size 25-35%, while control cancers increased >250%. Biomarkers. Levels of phosphorylated ERK were strongly decreased in rats treated daily/weekly with erlotinib. Thus, altering the dosing of erlotinib retained most of its preventive and therapeutic efficacy.
    Cancer Prevention Research 03/2013; · 4.89 Impact Factor
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    ABSTRACT: Examining three RXR agonists [Targretin (TRG), UAB30, and 4-methyl-UAB30 (4-Me-UAB30)], all inhibited mammary cancer in rodents and two (TRG and 4-Me-UAB30) strikingly increased serum triglycerides levels. Agents were administered in diets to female Sprague-Dawley rats. Liver RNA was isolated and microarrayed on the Affymetrix GeneChip Rat Exon 1.0 ST array. Statistical tests identified genes that exhibited differential expression and fell into groups, or modules, with differential expression among agonists. Genes in specific modules were changed by one two or all three agonists. An interactome analysis assessed the effects on genes which heterodimerize with known nuclear receptors. For PPARα/RXR activated genes, the strongest response was TRG > 4-Me-UAB30>UAB30. Many LXR/RXR related genes (e.g., SCD-1 and SREBP-1c which are associated with increased triglycerides) were highly expressed in TRG and 4-Me-UAB30 but not UAB30 treated livers. There was minimal expression changes associated with RAR or VDR heterodimers by any of the agonists. UAB30 unexpectedly and uniquely activated genes associated with the Ah receptor (Cyp1a1, Cyp1a2, Cyp1b1 and NQO1). Based on the Ah receptor activation, UAB30 was tested for its ability to prevent DMBA-induced mammary cancers, presumably by inhibiting DMBA activation, and was highly effective. Gene expression changes were determined by RT-PCR in rat livers treated with Targretin for 2.3, 7 and 21 days. These showed similar gene expression changes at all three time points; arguing some steady state effect. Different patterns of gene expression among the agonists provided insight into molecular differences, and allowed one to predict certain physiologic consequences of agonist treatment.
    Molecular pharmacology 01/2013; · 4.53 Impact Factor
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    ABSTRACT: Recent clinical trials raised concerns regarding the cardiovascular toxicity of selective cyclooxygenase-2 (COX-2) inhibitors. Many active dietary factors are reported to suppress carcinogenesis by targeting COX-2. A major question was accordingly raised: why has the lifelong use of phytochemicals that likely inhibit COX-2 presumably not been associated with adverse cardiovascular side effects. To answer this question, we selected a library of dietary-derived phytochemicals and evaluated their potential cardiovascular toxicity in human umbilical vein endothelial cells. Our data indicated that the possibility of cardiovascular toxicity of these dietary phytochemicals was low. Further mechanistic studies revealed that the actions of these phytochemicals were similar to aspirin in that they mainly inhibited COX-1 rather than COX-2, especially at low doses.
    PLoS ONE 01/2013; 8(10):e76452. · 3.73 Impact Factor
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    ABSTRACT: The sigma-2 receptor is expressed in higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells, thus providing an attractive target for imaging the proliferative status (i.e., P:Q ratio) of solid tumors. Here we evaluate the utility of the sigma-2 receptor ligand 2-(2-[(18)F]fluoroethoxy)-N-(4-(3,4-dihydro-6,7-dimethoxyisoquinolin-2(1H)-yl)butyl)-5-methyl-benzamide, [(18)F]ISO-1, in two different rodent models of breast cancer. In the first study, small animal Positron Emission Tomography (PET) imaging studies were conducted with [(18)F]ISO-1 and (18)FDG in xenografts of mouse mammary tumor 66 and tracer uptake was correlated with the in vivo P:Q ratio determined by flow cytometric measures of BrdU-labeled tumor cells. The second model utilized a chemically-induced (N-methyl-N-nitrosourea [MNU]) model of rat mammary carcinoma to correlate measures of [(18)F]ISO-1 and FDG uptake with MR-based volumetric measures of tumor growth. In addition, [(18)F]ISO-1 and FDG were used to assess the response of MNU-induced tumors to bexarotene and Vorozole therapy. In the mouse mammary 66 tumors, a strong linear correlation was observed between the [(18)F]ISO-1 tumor: background ratio and the proliferative status (P:Q ratio) of the tumor (R = 0.87). Similarly, measures of [(18)F]ISO-1 uptake in MNU-induced tumors significantly correlated (R = 0.68, P<0.003) with changes in tumor volume between consecutive MR imaging sessions. Our data suggest that PET studies of [(18)F]ISO-1 provide a measure of both the proliferative status and tumor growth rate, which would be valuable in designing an appropriate treatment strategy.
    PLoS ONE 01/2013; 8(9):e74188. · 3.73 Impact Factor
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    ABSTRACT: Introduction: In a variety of cancers there is evidence that specific regimens can prevent or significantly delay the development of cancer. Thus, for breast cancer (ER+) use of SERMs or aromatase inhibitors can substantially decrease tumor incidence. For cervical cancer, HPV vaccination will inhibit long term cancer incidence. For colon cancer, the second greatest cancer killer, administration of aspirin and other NSAIDs decreases advanced colon adenomas in Phase II trials and epidemiologic data support their ability to prevent colon cancer. To date prevention trials in the area of lung cancer have shown minimal efficacy. Areas covered: The paper examines and discusses in greater detail certain promising agents which the authors have tested either preclinically and or in early phase clinical trials. These agents include RXR agonists, EGFr inhibitors, NSAIDs and Triterpenoids. Other agents including glucocorticoids, pioglitazone and iloprost are briefly mentioned. In addition, the paper presents various types of potential Phase II lung cancer prevention trials and describes their strengths and weaknesses. The potential use of various biomarkers as endpoints in trials e.g. histopathology, non-specific biomarkers (e.g., Ki67, cyclin D expression, apoptosis) and molecular biomarkers (e.g. specific phosphorylated proteins, gene expression etc.) is presented. Finally, we examine at least one approach, the use of aerosols, which may diminish the systemic toxicity associated with certain of these agents. Expert Opinion: The manuscript presents: a) a number of promising agents which appear applicable to further Phase II prevention trials; b) approaches to defining potential preventive agents as well; c) approaches which might mitigate the side effects associated with potential agents most specifically the use of aerosols. Finally, we discuss biomarker studies both preclinical and clinical which might help support potential Phase II trials. The particular appeal to the preclinical studies is that they can be followed to a tumor endpoint. We hope that this will give the reader further background and allow one to appreciate the potential and some of the hurdles associated with lung cancer chemoprevention.
    Expert Opinion on Investigational Drugs 11/2012; · 4.74 Impact Factor
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    ABSTRACT: Aurora kinases play an important role in chromosome alignment, segregation, and cytokinesis during mitosis. In the present study, we used a ligand-docking method to explore the novel scaffold of potential Aurora B inhibitors. One thousand compounds from our in-house compound library were screened against the Aurora B structure and one compound, (E)-3-((E)-4-(benzo[d][1,3]dioxol-5-yl)-2-oxobut-3-en-1-ylidene)indolin-2-one (designated herein as HOI-07) was selected for further study. HOI-07 potently inhibited in vitro Aurora B kinase activity in a dose-dependent manner, without obvious inhibition of another 49 kinases, including Aurora A. This compound suppressed Aurora B kinase activity in lung cancer cells, evidenced by the inhibition of the phosphorylation of histone H3 on Ser10 in a dose- and time-dependent manner. This inhibition resulted in apoptosis induction, G2/M arrest, polyploidy cells, and attenuation of cancer cell anchorage-independent growth. Moreover, knocking down the expression of Aurora B effectively reduced the sensitivity of cancer cells to HOI-07. Results of an in vivo xenograft mouse study showed that HOI-07 treatment effectively suppressed the growth of A549 xenografts, without affecting the body weight of mice. The expression of phospho-histone H3, phospho-Aurora B, and Ki-67 was also suppressed in the HOI-07 treatment group. Taken together, we identified HOI-07 as a specific Aurora B inhibitor, which deserves further investigation.
    Cancer Research 11/2012; · 9.28 Impact Factor
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    ABSTRACT: Ceftriaxone, an FDA-approved third-generation cephalosporin antibiotic, has antimicrobial activity against both gram-positive and gram-negative organisms. Generally, ceftriaxone is used for a variety of infections such as community-acquired pneumonia, meningitis and gonorrhea. Its primary molecular targets are the penicillin-binding proteins. However, other activities of ceftriaxone remain unknown. Herein, we report for the first time that ceftriaxone has antitumor activity in vitro and in vivo. Kinase profiling results predicted that Aurora B might be a potential 'off' target of ceftriaxone. Pull-down assay data confirmed that ceftriaxone could bind with Aurora B in vitro and in A549 cells. Furthermore, ceftriaxone (500 µM) suppressed anchorage-independent cell growth by targeting Aurora B in A549, H520 and H1650 lung cancer cells. Importantly, in vivo xenograft animal model results showed that ceftriaxone effectively suppressed A549 and H520 lung tumor growth by inhibiting Aurora B. These data suggest the anticancer efficacy of ceftriaxone for the treatment of lung cancers through its inhibition of Aurora B.
    Carcinogenesis 09/2012; · 5.64 Impact Factor
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    ABSTRACT: Skin cancer is one of the most commonly diagnosed cancers in the United States. Taxifolin reportedly exerts multiple biologic effects, but the molecular mechanisms and direct target(s) of taxifolin in skin cancer chemoprevention are still unknown. In silico computer screening and kinase profiling results suggest that the EGF receptor (EGFR), phosphoinositide 3-kinase (PI3K), and Src are potential targets for taxifolin. Pull-down assay results showed that EGFR, PI3K, and Src directly interacted with taxifolin in vitro, whereas taxifolin bound to EGFR and PI3K, but not to Src in cells. ATP competition and in vitro kinase assay data revealed that taxifolin interacted with EGFR and PI3K at the ATP-binding pocket and inhibited their kinase activities. Western blot analysis showed that taxifolin suppressed UVB-induced phosphorylation of EGFR and Akt, and subsequently suppressed their signaling pathways in JB6 P+ mouse skin epidermal cells. Expression levels and promoter activity of COX-2 and prostaglandin E(2) (PGE(2)) generation induced by UVB were also attenuated by taxifolin. The effect of taxifolin on UVB-induced signaling pathways and PGE(2) generation was reduced in EGFR knockout murine embryonic fibroblasts (MEF) compared with EGFR wild-type MEFs. Taxifolin also inhibited EGF-induced cell transformation. Importantly, topical treatment of taxifolin to the dorsal skin significantly suppressed tumor incidence, volume, and multiplicity in a solar UV (SUV)-induced skin carcinogenesis mouse model. Further analysis showed that the taxifolin-treated group had a substantial reduction in SUV-induced phosphorylation of EGFR and Akt in mouse skin. These results suggest that taxifolin exerts chemopreventive activity against UV-induced skin carcinogenesis by targeting EGFR and PI3K. Cancer Prev Res; 5(9); 1103-14. ©2012 AACR.
    Cancer Prevention Research 07/2012; 5(9):1103-14. · 4.89 Impact Factor
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    ABSTRACT: N-(4-hydroxyphenyl) retinamide (4HPR, fenretinide) is a synthetic retinoid that has been tested in clinical trials as a cancer therapeutic and chemopreventive agent. Although 4HPR has been shown to be cytotoxic to many kinds of cancer cells, the underlying molecular mechanisms are only partially understood. Until now, no direct cancer-related molecular target has been reported to be involved in the antitumor activities of 4HPR. Herein, we found that 4HPR inhibited mammalian target of rapamycin (mTOR) kinase activity by directly binding with mTOR, which suppressed the activities of both the mTORC1 and the mTORC2 complexes. The predicted binding mode of 4HPR with mTOR was based on a homology computer model, which showed that 4HPR could bind in the ATP-binding pocket of the mTOR protein through hydrogen bonds and hydrophobic interactions. In vitro studies also showed that 4HPR attenuated mTOR downstream signaling in a panel of non-small-cell lung cancer cells, resulting in growth inhibition. Moreover, knockdown of mTOR in cancer cells decreased their sensitivity to 4HPR. Results of an in vivo study demonstrated that i.p. injection of 4HPR in A549 lung tumor-bearing mice effectively suppressed cancer growth. The expression of mTOR downstream signaling molecules in tumor tissues was also decreased after 4HPR treatment. Taken together, our results are the first to identify mTOR as a direct antitumor target of 4HPR both in vitro and in vivo, providing a valuable rationale for guiding the clinical uses of 4HPR.
    Carcinogenesis 07/2012; 33(9):1814-21. · 5.64 Impact Factor
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    ABSTRACT: The chemopreventive efficacy of Targretin was evaluated in various rodent cancer models. In the rat model of 4-hydroxybutyl(butyl)nitrosamine (OH-BBN)-induced urinary bladder cancer, it was found that Targretin administered in the diet (beginning one week after the last OH-BBN treatment) for 5.5 months increased the number and size of urinary bladder cancers. In the azoxymethane (AOM)-induced model of colon carcinogenesis (in which rats develop minimally invasive colonic cancers), Targretin was ineffective as a chemopreventive agent, decreasing neither tumor incidence nor multiplicity. Treatment of Min mice with Targretin for 45 days similarly failed to decrease the multiplicity of small intestinal tumors. Similarly, no preventive efficacy was noted for Targretin when the incidence of tumors in the head and neck model (squamous cell tongue tumors) induced by 4-nitroquinoline 1-oxide (4-NQO) were examined. In contrast, use of even a suboptimal dose of Targretin (40 ppm) in a sensitive breast cancer model [methylnitrosourea (MNU)-induced ER+ mammary cancers] reduced cancer multiplicity by 60%. Finally, based on the hypothesis that Targretin may decrease the expression of COX‑2, the effects of Targretin and COX inhibitors were compared in these models. There was minimal overlap of efficacy. That is, models which were relatively susceptible to NSAIDs or COX-2 inhibitors tended not to be sensitive to Targretin and vice versa.
    Oncology Reports 05/2012; 27(5):1400-6. · 2.30 Impact Factor
  • Qi Zhang, Jing Pan, Yian Wang, Ronald Lubet, Ming You
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    ABSTRACT: Betanin, also called beetroot red, has been extensively used as a food colorant. In this study, the chemopreventive activity of betanin by oral consumption was investigated in two mouse lung tumor models. Vinyl carbamate (VC) and benzo(a)pyrene (B(a)P) were used to induce lung tumors, and female A/J mice were treated with betanin in drinking water. Betanin significantly decreased tumor multiplicity and tumor load induced by both carcinogens. Tumor multiplicity and tumor load were decreased by 20% and 39% in the VC lung model, and by 46% and 65% in the B(a)P lung model, respectively. Betanin reduced the number of CD31+ endothelial microvessels and increased the expression of caspase-3, suggesting that the lung tumor inhibitory effects were through induction of apoptosis and inhibition of angiogenesis. Betanin also induced apoptosis through activated caspase-3, -7, -9, and PARP in human lung cancer cell lines. Our data show that betanin significantly inhibits lung tumorigenesis in A/J mice and merits investigation as a chemopreventive agent for human lung cancer. © 2012 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 03/2012; · 4.27 Impact Factor
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    ABSTRACT: 3-Bromopyruvate, an alkylating agent and a well-known inhibitor of energy metabolism, has been proposed as a specific anticancer agent. However, the chemopreventive effect of 3-bromopyruvate in lung tumorigenesis has not been tested. In this study, we investigated the chemopreventive activity of 3-bromopyruvate in a mouse lung tumor model. Benzo(a)pyrene was used to induce lung tumors, and 3-bromopyruvate was administered by oral gavage to female A/J mice. We found that 3-bromopyruvate significantly decreased tumor multiplicity and tumor load by 58% and 83%, respectively, at a dose of 20 mg/kg body weight by gavage. Due to the known liver toxicity of 3-bromopyruvate in animal models given large doses of 3-bromopyruvate, confirmed in this study, we decided to test the chemopreventive activity of aerosolized 3-bromopyruvate in the same lung tumor model. As expected, aerosolized 3-bromopyruvate similarly significantly decreased tumor multiplicity and tumor load by 49% and 80%, respectively, at a dose of 10 mg/mL by inhalation. Interestingly, the efficacy of aerosolized 3-bromopyruvate did not accompany any liver toxicity indicating that it is a safer route of administering this compound. Treatment with 3-bromopyruvate increased immunohistochemical staining for cleaved caspase-3, suggesting that the lung tumor inhibitory effects of 3-bromopyruvate were through induction of apoptosis. 3-Bromopyruvate also dissociated hexokinase II from mitochondria, reduced hexokinase activity, and blocked energy metabolism in cancer cells, finally triggered cancer cell death and induced apoptosis through caspase-3, and PARP in human lung cancer cell line. The ability of 3-bromopyruvate to inhibit mouse lung tumorigenesis, in part through induction of apoptosis, merits further investigation of this compound as a chemopreventive agent for human lung cancer.
    Cancer Prevention Research 03/2012; 5(5):717-25. · 4.89 Impact Factor

Publication Stats

8k Citations
1,560.51 Total Impact Points

Institutions

  • 1989–2014
    • National Cancer Institute (USA)
      • Division of Cancer Prevention
      Maryland, United States
  • 2013
    • Medical College of Wisconsin
      Milwaukee, Wisconsin, United States
  • 2010–2013
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
  • 2005–2012
    • Washington University in St. Louis
      • • Alvin J. Siteman Cancer Center
      • • Department of Energy, Environmental, and Chemical Engineering
      • • Department of Surgery
      Saint Louis, MO, United States
  • 2003–2012
    • University of Washington Seattle
      • • Department of Surgery
      • • Department of Radiology
      Seattle, WA, United States
  • 1995–2012
    • National Institutes of Health
      • • Group of Chemopreventive Agent Development Research
      • • Division of Cancer Prevention
      Maryland, United States
    • Leidos Biomedical Research
      Maryland, United States
    • NCI-Frederick
      Maryland, United States
  • 2011
    • Guangdong Medical College
      Tung-kuan, Guangdong, China
  • 2001–2011
    • University of Texas MD Anderson Cancer Center
      • • Department of Molecular Carcinogenesis
      • • Science Park - Research Division
      Houston, TX, United States
  • 1994–2010
    • IIT Research Institute (IITRI)
      Chicago, Illinois, United States
  • 1995–2008
    • Medical University of Ohio at Toledo
      • • Department of Biochemistry and Cancer Biology
      • • Department of Surgery
      Toledo, Ohio, United States
  • 1997–2007
    • The Ohio State University
      • • Division of Hematology
      • • Division of Human Genetics
      Columbus, OH, United States
  • 1996–2007
    • University of Illinois at Chicago
      • Department of Surgical Oncology (Chicago)
      Chicago, IL, United States
  • 1999–2006
    • Università degli Studi di Genova
      • Dipartimento di Scienze della salute (DISSAL)
      Genova, Liguria, Italy
  • 2001–2004
    • University of Alabama at Birmingham
      • • Department of Nutrition Sciences (HP)
      • • Department of Pathology
      Birmingham, AL, United States
  • 2000–2004
    • University of Wisconsin–Madison
      • Department of Medicine
      Madison, Wisconsin, United States
  • 1998
    • National Institute on Aging
      • Laboratory of Neurosciences (LNS)
      Baltimore, MD, United States
    • National Eye Institute
      Maryland, United States
    • Oklahoma State University - Stillwater
      • Department of Zoology
      Stillwater, OK, United States
  • 1988
    • Argonne National Laboratory
      Lemont, Illinois, United States
  • 1979
    • University of Texas Health Science Center at Tyler
      Tyler, Texas, United States
  • 1971
    • The University of Tennessee Medical Center at Knoxville
      Knoxville, Tennessee, United States