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Zhang L, Sun Q, Ou Y, Zhang Q, Hu J. Metformin Induces Cytotoxicity in Oral Squamous Cell Carcinoma Cells by Targeting CCN1/Akt-Axis. INT J PHARMACOL 2022. [DOI: 10.3923/ijp.2022.182.189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Liaqat S, Islam M, Saeed H, Iqtedar M, Mehmood A. Investigation of Olea ferruginea Roylebark extracts for potential in vitroantidiabetic and anticancer effects. Turk J Chem 2021; 45:92-103. [PMID: 33679156 PMCID: PMC7925318 DOI: 10.3906/kim-2006-51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/19/2020] [Indexed: 11/05/2022] Open
Abstract
This study was conducted to investigate the physicochemical, phytochemical, in vitro antidiabetic and anticancer potential of
Olea ferruginea
R bark. After extraction using Soxhlet, in vitro antidiabetic and cytotoxic activity on human hepatocellular carcinoma (HepG2) cells was assessed by nonenzymatic glycosylation of hemoglobin assay, alpha-amylase inhibition assay, glucose uptake by yeast cells, and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay, respectively, and gene expression via real-time polymerase chain reaction. Primary and secondary metabolites were present in the extractants; polyphenols (35.61 ± 0.03) and flavonoids (64.33 ± 0.35
)
in the chloroform; and polysaccharides in the ethanol (268.75 ± 0.34), and glycosaponins (78.01 ± 0.07) in the methanol. The chloroform extract exhibited maximum antidiabetic potential, showing inhibition of nonenzymatic glycosylation of hemoglobin (65%), and alpha-amylase inhibition (32%) with maximum percent glucose uptake by the ethanol extract (78%). Only the ethanol extract had dose-dependent cytotoxic potential against the HepG2 cells. After 24-h exposure to the ethanol-extract, the expression of protein kinase B (Akt) remained unchanged, while the expression of B-cell lymphoma 2 (BCL2) and BCL2 associated X (BAX) changed significantly. After 48-h exposure, the expression of Akt decreased significantly, while that of BCL2 and BAX increased significantly.
Olea ferruginea
R bark possessed in vitro antidiabetic potential and anticancer/cytotoxic effects, attributable to the decline in the prosurvival signals of the Akt signaling pathway.
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Affiliation(s)
- Samra Liaqat
- University College of Pharmacy, University of the Punjab, Lahore Pakistan
| | - Muhammad Islam
- University College of Pharmacy, University of the Punjab, Lahore Pakistan
| | - Hamid Saeed
- University College of Pharmacy, University of the Punjab, Lahore Pakistan
| | - Mehwish Iqtedar
- Department of Biotechnology, Lahore College for Women University, Lahore Pakistan
| | - Azra Mehmood
- Center for Excellence in Molecular Biology, University of the Punjab, Lahore Pakistan
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Jayathilake AG, Veale MF, Luwor RB, Nurgali K, Su XQ. Krill oil extract inhibits the migration of human colorectal cancer cells and down-regulates EGFR signalling and PD-L1 expression. BMC Complement Med Ther 2020; 20:372. [PMID: 33287803 PMCID: PMC7720407 DOI: 10.1186/s12906-020-03160-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/17/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The currently available treatments for colorectal cancer (CRC) are often associated with serious side-effects. Therefore, the development of a novel nutraceutical agent may provide an alternative complementary therapy for CRC. Overexpression of the epidermal growth factor receptor (EGFR) associates with a range of cancers while downregulation of EGFR signalling can inhibit cancer growth. Our previous studies have shown that the free fatty acid extract (FFAE) of krill oil exhibits anti-proliferative and pro-apoptotic properties. This study determines the effects of krill oil extract on the migration of human CRC cells, and its potential role in modulating EGFR signalling pathway and the expression of programmed death ligand 1 (PD-L1). METHODS Human CRC cells, DLD-1 and HT-29 were treated with FFAE of KO at 0.03 and 0.12 μL/100 μL for 8 or 24 h. Cell migration was determined by Boyden chamber migration assay. The expression of EGFR, phosphorylated EGFR (pEGFR), protein kinase B (AKT), phosphorylated AKT (pAKT), extracellular signal regulated kinase (ERK1/2), phosphorylated ERK1/2 (pERK1/2) as well as PD-L1 were assessed by western blotting and immunohistochemistry. RESULTS The FFAE of krill oil significantly inhibited cell migration compared to ethanol-treated (vehicle control) cells (P < 0.01 to P < 0.001). At the molecular level, krill oil extract reduced the expression of EGFR, pEGFR (P < 0.001 for both) and their downstream signalling, pERK1/2 and pAKT (P < 0.01 to P < 0.001) without altering total ERK 1/2 and AKT levels. In addition, the expression of PD-L1 was reduced by 67 to 72% (P < 0.001) following the treatment with krill oil extract. CONCLUSION This study has demonstrated that krill oil may be a potential therapeutic/adjunctive agent for CRC attributed to its anti-migratory effects.. The potential anti-cancer properties of krill oil are likely to be associated with the downregulation of EGFR, pEGFR and their downstream pERK/ERK1/2 and pAKT/AKT signalling pathways along with the downregulation of PD-L1.
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Affiliation(s)
- Abilasha G. Jayathilake
- Institute for Health and Sport, Victoria University, P.O. Box 14428, Melbourne, Vic 8001 Australia
| | - Margaret F. Veale
- Institute for Health and Sport, Victoria University, P.O. Box 14428, Melbourne, Vic 8001 Australia
| | - Rodney Brain Luwor
- Department of Surgery, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Australia
| | - Kulmira Nurgali
- Institute for Health and Sport, Victoria University, P.O. Box 14428, Melbourne, Vic 8001 Australia
- Department of Medicine, Western Health, The University of Melbourne, Melbourne, Australia
- Regenerative Medicine and Stem Cell Program, Australian Institute for Muscular Skeletal Science (AIMSS), Melbourne, Australia
| | - Xiao Q. Su
- Institute for Health and Sport, Victoria University, P.O. Box 14428, Melbourne, Vic 8001 Australia
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Umesalma S, Kaemmer CA, Kohlmeyer JL, Letney B, Schab AM, Reilly JA, Sheehy RM, Hagen J, Tiwari N, Zhan F, Leidinger MR, O'Dorisio TM, Dillon J, Merrill RA, Meyerholz DK, Perl AL, Brown BJ, Braun TA, Scott AT, Ginader T, Taghiyev AF, Zamba GK, Howe JR, Strack S, Bellizzi AM, Narla G, Darbro BW, Quelle FW, Quelle DE. RABL6A inhibits tumor-suppressive PP2A/AKT signaling to drive pancreatic neuroendocrine tumor growth. J Clin Invest 2019; 129:1641-1653. [PMID: 30721156 DOI: 10.1172/jci123049] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/24/2019] [Indexed: 12/15/2022] Open
Abstract
Hyperactivated AKT/mTOR signaling is a hallmark of pancreatic neuroendocrine tumors (PNETs). Drugs targeting this pathway are used clinically, but tumor resistance invariably develops. A better understanding of factors regulating AKT/mTOR signaling and PNET pathogenesis is needed to improve current therapies. We discovered that RABL6A, a new oncogenic driver of PNET proliferation, is required for AKT activity. Silencing RABL6A caused PNET cell-cycle arrest that coincided with selective loss of AKT-S473 (not T308) phosphorylation and AKT/mTOR inactivation. Restoration of AKT phosphorylation rescued the G1 phase block triggered by RABL6A silencing. Mechanistically, loss of AKT-S473 phosphorylation in RABL6A-depleted cells was the result of increased protein phosphatase 2A (PP2A) activity. Inhibition of PP2A restored phosphorylation of AKT-S473 in RABL6A-depleted cells, whereas PP2A reactivation using a specific small-molecule activator of PP2A (SMAP) abolished that phosphorylation. Moreover, SMAP treatment effectively killed PNET cells in a RABL6A-dependent manner and suppressed PNET growth in vivo. The present work identifies RABL6A as a new inhibitor of the PP2A tumor suppressor and an essential activator of AKT in PNET cells. Our findings offer what we believe is a novel strategy of PP2A reactivation for treatment of PNETs as well as other human cancers driven by RABL6A overexpression and PP2A inactivation.
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Affiliation(s)
| | | | | | | | | | | | - Ryan M Sheehy
- Department of Pharmacology.,Free Radical & Radiation Biology Training Program
| | | | | | | | - Mariah R Leidinger
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | | | | | | | - David K Meyerholz
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | - Abbey L Perl
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | | - Agshin F Taghiyev
- Pediatrics, Colleges of Medicine, Engineering, or Public Health, University of Iowa, Iowa City, Iowa, USA
| | | | | | | | - Andrew M Bellizzi
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | - Goutham Narla
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Benjamin W Darbro
- Pediatrics, Colleges of Medicine, Engineering, or Public Health, University of Iowa, Iowa City, Iowa, USA
| | | | - Dawn E Quelle
- Department of Pharmacology.,Molecular Medicine Graduate Program.,Free Radical & Radiation Biology Training Program.,Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
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Wittenberg AD, Azar S, Klochendler A, Stolovich-Rain M, Avraham S, Birnbaum L, Binder Gallimidi A, Katz M, Dor Y, Meyuhas O. Phosphorylated Ribosomal Protein S6 Is Required for Akt-Driven Hyperplasia and Malignant Transformation, but Not for Hypertrophy, Aneuploidy and Hyperfunction of Pancreatic β-Cells. PLoS One 2016; 11:e0149995. [PMID: 26919188 PMCID: PMC4769037 DOI: 10.1371/journal.pone.0149995] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/08/2016] [Indexed: 12/31/2022] Open
Abstract
Constitutive expression of active Akt (Akttg) drives hyperplasia and hypertrophy of pancreatic β-cells, concomitantly with increased insulin secretion and improved glucose tolerance, and at a later stage the development of insulinoma. To determine which functions of Akt are mediated by ribosomal protein S6 (rpS6), an Akt effector, we generated mice that express constitutive Akt in β-cells in the background of unphosphorylatable ribosomal protein S6 (rpS6P-/-). rpS6 phosphorylation deficiency failed to block Akttg-induced hypertrophy and aneuploidy in β-cells, as well as the improved glucose homeostasis, indicating that Akt carries out these functions independently of rpS6 phosphorylation. In contrast, rpS6 phosphorylation deficiency efficiently restrained the reduction in nuclear localization of the cell cycle inhibitor p27, as well as the development of Akttg-driven hyperplasia and tumor formation in β-cells. In vitro experiments with Akttg and rpS6P-/-;Akttg fibroblasts demonstrated that rpS6 phosphorylation deficiency leads to reduced translation fidelity, which might underlie its anti-tumorigenic effect in the pancreas. However, the role of translation infidelity in tumor suppression cannot simply be inferred from this heterologous experimental model, as rpS6 phosphorylation deficiency unexpectedly elevated the resistance of Akttg fibroblasts to proteotoxic, genotoxic as well as autophagic stresses. In contrast, rpS6P-/- fibroblasts exhibited a higher sensitivity to these stresses upon constitutive expression of oncogenic Kras. The latter result provides a possible mechanistic explanation for the ability of rpS6 phosphorylation deficiency to enhance DNA damage and protect mice from Kras-induced neoplastic transformation in the exocrine pancreas. We propose that Akt1 and Kras exert their oncogenic properties through distinct mechanisms, even though both show addiction to rpS6 phosphorylation.
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Affiliation(s)
- Avigail Dreazen Wittenberg
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shahar Azar
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Agnes Klochendler
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Miri Stolovich-Rain
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shlomit Avraham
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Lea Birnbaum
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Adi Binder Gallimidi
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Maximiliano Katz
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Yang Z, Huang N, Xu B, Huang W, Xie T, Cheng F, Zou K. Cytotoxic 1,3-Thiazole and 1,2,4-Thiadiazole Alkaloids from Penicillium oxalicum: Structural Elucidation and Total Synthesis. Molecules 2016; 21:232. [PMID: 26927049 PMCID: PMC6273271 DOI: 10.3390/molecules21030232] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 02/14/2016] [Accepted: 02/15/2016] [Indexed: 01/26/2023] Open
Abstract
Two new thiazole and thiadiazole alkaloids, penicilliumthiamine A and B (2 and 3), were isolated from the culture broth of Penicillium oxalicum, a fungus found in Acrida cinerea. Their structures were elucidated mainly by spectroscopic analysis, total synthesis and X-ray crystallographic analysis. Biological evaluations indicated that compound 1, 3a and 3 exhibit potent cytotoxicity against different cancer cell lines through inhibiting the phosphorylation of AKT/PKB (Ser 473), one of important cancer drugs target.
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Affiliation(s)
- Zheng Yang
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
| | - Nianyu Huang
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
| | - Bang Xu
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
- China Three Gorges University People's Hospital & Yichang First People's Hospital, Yichang 443000, China.
| | - Wenfeng Huang
- Hubei Key Laboratory of Natural Products Research and Development, Medical College, China Three Gorges University, Yichang 443002, China.
| | - Tianpeng Xie
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
| | - Fan Cheng
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
| | - Kun Zou
- Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
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7
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Lobo MR, Wang X, Gillespie GY, Woltjer RL, Pike MM. Combined efficacy of cediranib and quinacrine in glioma is enhanced by hypoxia and causally linked to autophagic vacuole accumulation. PLoS One 2014; 9:e114110. [PMID: 25490024 PMCID: PMC4260788 DOI: 10.1371/journal.pone.0114110] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 11/03/2014] [Indexed: 11/18/2022] Open
Abstract
We have previously reported that the in vivo anti-glioma efficacy of the anti-angiogenic receptor tyrosine kinase inhibitor cediranib is substantially enhanced via combination with the late-stage autophagy inhibitor quinacrine. The current study investigates the role of hypoxia and autophagy in combined cediranib/quinacrine efficacy. EF5 immunostaining revealed a prevalence of hypoxia in mouse intracranial 4C8 glioma, consistent with high-grade glioma. MTS cell viability assays using 4C8 glioma cells revealed that hypoxia potentiated the efficacy of combined cediranib/quinacrine: cell viability reductions induced by 1 µM cediranib +2.5 µM quinacrine were 78±7% (hypoxia) vs. 31±3% (normoxia), p<0.05. Apoptosis was markedly increased for cediranib/quinacrine/hypoxia versus all other groups. Autophagic vacuole biomarker LC3-II increased robustly in response to cediranib, quinacrine, or hypoxia. Combined cediranib/quinacrine increased LC3-II further, with the largest increases occurring with combined cediranib/quinacrine/hypoxia. Early stage autophagy inhibitor 3-MA prevented LC3-II accumulation with combined cediranib/quinacrine/hypoxia and substantially attenuated the associated reduction in cell viability. Combined efficacy of cediranib with bafilomycin A1, another late-stage autophagy inhibitor, was additive but lacked substantial potentiation by hypoxia. Substantially lower LC3-II accumulation was observed with bafilomycin A1 in comparison to quinacrine. Cediranib and quinacrine each strongly inhibited Akt phosphoryation, while bafilomycin A1 had no effect. Our results provide compelling evidence that autophagic vacuole accumulation plays a causal role in the anti-glioma cytotoxic efficacy of combined cediranib/quinacrine. Such accumulation is likely related to stimulation of autophagosome induction by hypoxia, which is prevalent in the glioma tumor microenvironment, as well as Akt signaling inhibition from both cediranib and quinacrine. Quinacrine's unique ability to inhibit both Akt and autophagic vacuole degradation may enhance its ability to drive cytotoxic autophagic vacuole accumulation. These findings provide a rationale for a clinical evaluation of combined cediranib/quinacrine therapy for malignant glioma.
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Affiliation(s)
- Merryl R. Lobo
- Advanced Imaging Research Center, Oregon Health and Science University, Portland, Oregon, United States of America
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Xiaoyan Wang
- Department of Molecular and Medical Genetics at Oregon Health and Science University, Portland, Oregon, United States of America
| | - G. Yancey Gillespie
- Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Randall L. Woltjer
- Department of Pathology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Martin M. Pike
- Advanced Imaging Research Center, Oregon Health and Science University, Portland, Oregon, United States of America
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
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8
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Blanco E, Sangai T, Wu S, Hsiao A, Ruiz-Esparza GU, Gonzalez-Delgado CA, Cara FE, Granados-Principal S, Evans KW, Akcakanat A, Wang Y, Do KA, Meric-Bernstam F, Ferrari M. Colocalized delivery of rapamycin and paclitaxel to tumors enhances synergistic targeting of the PI3K/Akt/mTOR pathway. Mol Ther 2014; 22:1310-1319. [PMID: 24569835 DOI: 10.1038/mt.2014.27] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 02/13/2014] [Indexed: 12/19/2022] Open
Abstract
Ongoing clinical trials target the aberrant PI3K/Akt/mammalian target of rapamycin (mTOR) pathway in breast cancer through administration of rapamycin, an allosteric mTOR inhibitor, in combination with paclitaxel. However, synergy may not be fully exploited clinically because of distinct pharmacokinetic parameters of drugs. This study explores the synergistic potential of site-specific, colocalized delivery of rapamycin and paclitaxel through nanoparticle incorporation. Nanoparticle drug loading was accurately controlled, and synergistic drug ratios established in vitro. Precise drug ratios were maintained in tumors 48 hours after nanoparticle administration to mice, at levels twofold greater than liver and spleen, yielding superior antitumor activity compared to controls. Simultaneous and preferential in vivo delivery of rapamycin and paclitaxel to tumors yielded mechanistic insights into synergy involving suppression of feedback loop Akt phosphorylation and its downstream targets. Findings demonstrate that a same time, same place, and specific amount approach to combination chemotherapy by means of nanoparticle delivery has the potential to successfully translate in vitro synergistic findings in vivo. Predictive in vitro models can be used to determine optimum drug ratios for antitumor efficacy, while nanoparticle delivery of combination chemotherapies in preclinical animal models may lead to enhanced understanding of mechanisms of synergy, ultimately opening several avenues for personalized therapy.
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Affiliation(s)
- Elvin Blanco
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Takafumi Sangai
- Department of Surgical Oncology, University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Suhong Wu
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Angela Hsiao
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Guillermo U Ruiz-Esparza
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA; Escuela de Biotecnología y Alimentos y Escuela de Medicina, Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Mexico
| | - Carlos A Gonzalez-Delgado
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA; Escuela de Biotecnología y Alimentos y Escuela de Medicina, Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Mexico
| | - Francisca E Cara
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA
| | | | - Kurt W Evans
- Department of Surgical Oncology, University of Texas, MD Anderson Cancer Center, Houston, Texas, USA; Department of Investigational Cancer Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Argun Akcakanat
- Department of Surgical Oncology, University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Ying Wang
- Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Kim-Anh Do
- Department of Biostatistics, University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Funda Meric-Bernstam
- Department of Surgical Oncology, University of Texas, MD Anderson Cancer Center, Houston, Texas, USA; Department of Investigational Cancer Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
| | - Mauro Ferrari
- Department of Nanomedicine, The Houston Methodist Research Institute, Houston, Texas, USA.
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Circumventing cellular control of PP2A by methylation promotes transformation in an Akt-dependent manner. Neoplasia 2013; 14:585-99. [PMID: 22904676 DOI: 10.1593/neo.12768] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 06/13/2012] [Accepted: 06/18/2012] [Indexed: 12/28/2022]
Abstract
Heterotrimeric protein phosphatase 2A (PP2A) consists of catalytic C (PP2Ac), structural A, and regulatory B-type subunits, and its dysfunction has been linked to cancer. Reversible methylation of PP2Ac by leucine carboxyl methyltransferase 1 (LCMT-1) and protein phosphatase methylesterase 1 (PME-1) differentially regulates B-type subunit binding and thus PP2A function. Polyomavirus middle (PyMT) and small (PyST) tumor antigens and SV40 small tumor antigen (SVST) are oncoproteins that block PP2A function by replacing certain B-type subunits, resulting in cellular transformation. Whereas the B-type subunits replaced by these oncoproteins seem to exhibit a binding preference for methylated PP2Ac, PyMT does not. We hypothesize that circumventing the normal cellular control of PP2A by PP2Ac methylation is a general strategy for ST- and MT-mediated transformation. Two predictions of this hypothesis are (1) that PyST and SVST also bind PP2A in a methylation-insensitive manner and (2) that down-regulation of PP2Ac methylation will activate progrowth and prosurvival signaling and promote transformation. We found that SVST and PyST, like PyMT, indeed form PP2A heterotrimers independently of PP2Ac methylation. In addition, reducing PP2Ac methylation through LCMT-1 knockdown or PME-1 overexpression enhanced transformation by activating the Akt and p70/p85 S6 kinase (S6K) pathways, pathways also activated by MT and ST oncoproteins. These results support the hypothesis that MT and ST oncoproteins circumvent cellular control of PP2A by methylation to promote transformation. They also implicate LCMT-1 as a negative regulator of Akt and p70/p85 S6K. Therefore, disruption of PP2Ac methylation may contribute to cancer, and modulation of this methylation may serve as an anticancer target.
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10
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Akt: a double-edged sword in cell proliferation and genome stability. JOURNAL OF ONCOLOGY 2012; 2012:951724. [PMID: 22481935 PMCID: PMC3317191 DOI: 10.1155/2012/951724] [Citation(s) in RCA: 173] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 12/29/2011] [Indexed: 01/31/2023]
Abstract
The Akt family of serine/threonine protein kinases are key regulators of multiple aspects of cell behaviour, including proliferation, survival, metabolism, and tumorigenesis. Growth-factor-activated Akt signalling promotes progression through normal, unperturbed cell cycles by acting on diverse downstream factors involved in controlling the G1/S and G2/M transitions. Remarkably, several recent studies have also implicated Akt in modulating DNA damage responses and genome stability. High Akt activity can suppress ATR/Chk1 signalling and homologous recombination repair (HRR) via direct phosphorylation of Chk1 or TopBP1 or, indirectly, by inhibiting recruitment of double-strand break (DSB) resection factors, such as RPA, Brca1, and Rad51, to sites of damage. Loss of checkpoint and/or HRR proficiency is therefore a potential cause of genomic instability in tumor cells with high Akt. Conversely, Akt is activated by DNA double-strand breaks (DSBs) in a DNA-PK- or ATM/ATR-dependent manner and in some circumstances can contribute to radioresistance by stimulating DNA repair by nonhomologous end joining (NHEJ). Akt therefore modifies both the response to and repair of genotoxic damage in complex ways that are likely to have important consequences for the therapy of tumors with deregulation of the PI3K-Akt-PTEN pathway.
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11
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Ohka F, Natsume A, Wakabayashi T. Current trends in targeted therapies for glioblastoma multiforme. Neurol Res Int 2012; 2012:878425. [PMID: 22530127 PMCID: PMC3317017 DOI: 10.1155/2012/878425] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/21/2011] [Accepted: 12/07/2011] [Indexed: 12/21/2022] Open
Abstract
Glioblastoma multiforme (GBM) is one of the most frequently occurring tumors in the central nervous system and the most malignant tumor among gliomas. Despite aggressive treatment including surgery, adjuvant TMZ-based chemotherapy, and radiotherapy, GBM still has a dismal prognosis: the median survival is 14.6 months from diagnosis. To date, many studies report several determinants of resistance to this aggressive therapy: (1) O(6)-methylguanine-DNA methyltransferase (MGMT), (2) the complexity of several altered signaling pathways in GBM, (3) the existence of glioma stem-like cells (GSCs), and (4) the blood-brain barrier. Many studies aim to overcome these determinants of resistance to conventional therapy by using various approaches to improve the dismal prognosis of GBM such as modifying TMZ administration and combining TMZ with other agents, developing novel molecular-targeting agents, and novel strategies targeting GSCs. In this paper, we review up-to-date clinical trials of GBM treatments in order to overcome these 4 hurdles and to aim at more therapeutical effect than conventional therapies that are ongoing or are about to launch in clinical settings and discuss future perspectives.
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Affiliation(s)
- Fumiharu Ohka
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Atsushi Natsume
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Toshihiko Wakabayashi
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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