201
|
Molecular mechanism of size control in development and human diseases. Cell Res 2011; 21:715-29. [PMID: 21483452 DOI: 10.1038/cr.2011.63] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
How multicellular organisms control their size is a fundamental question that fascinated generations of biologists. In the past 10 years, tremendous progress has been made toward our understanding of the molecular mechanism underlying size control. Original studies from Drosophila showed that in addition to extrinsic nutritional and hormonal cues, intrinsic mechanisms also play important roles in the control of organ size during development. Several novel signaling pathways such as insulin and Hippo-LATS signaling pathways have been identified that control organ size by regulating cell size and/or cell number through modulation of cell growth, cell division, and cell death. Later studies using mammalian cell and mouse models also demonstrated that the signaling pathways identified in flies are also conserved in mammals. Significantly, recent studies showed that dysregulation of size control plays important roles in the development of many human diseases such as cancer, diabetes, and hypertrophy.
Collapse
|
202
|
Li WJ, Park K, Paick J, Kim SW. Chronic Treatment with an Oral Rho‐Kinase Inhibitor Restores Erectile Function by Suppressing Corporal Apoptosis in Diabetic Rats. J Sex Med 2011; 8:400-10. [DOI: 10.1111/j.1743-6109.2010.01724.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
203
|
Abstract
Autophagy is a self-catabolic process that maintains intracellular homeostasis and prolongs cell survival under stress via lysosomal degradation of cytoplasmic constituents and recycling of amino acids and energy. Autophagy is intricately involved in many aspects of human health and disease, including cancer. Autophagy is a double-edged sword in tumorigenesis, acting both as a tumor suppressor and a protector of cancer cell survival, and elucidation of its exact role at different stages of cancer progression and in treatment responsiveness is a complex and challenging task. Better understanding of autophagy regulation and its impact on treatment outcome will potentially allow us to identify novel therapeutic targets in cancer. In this review, we summarize current knowledge on the regulation and dual function of autophagy in tumorigenesis, as well as ongoing efforts in modulating autophagy for cancer treatment and prevention. This is a very exciting and highly promising area of cancer research, as pharmacologic modulation of autophagy appears to augment the efficacy of currently available anticancer regimens and opens the way to the development of new combinatorial therapeutic strategies that will hopefully contribute to cancer eradication.
Collapse
Affiliation(s)
- Ning Chen
- University of Medicine and Dentistry of New Jersey, Piscataway, NJ, USA
| | | |
Collapse
|
204
|
Tang M, Iijima M, Kamimura Y, Chen L, Long Y, Devreotes P. Disruption of PKB signaling restores polarity to cells lacking tumor suppressor PTEN. Mol Biol Cell 2010; 22:437-47. [PMID: 21169559 PMCID: PMC3038642 DOI: 10.1091/mbc.e10-06-0522] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
By limiting phosphotidylinositol 3,4,5-triphosphate (PIP(3)) levels, tumor suppressor PTEN not only controls cell growth but also maintains cell polarity required for cytokinesis and chemotaxis. To identify the critical targets of PIP(3) that link it to the cytoskeleton, we deleted secondary genes to reverse the deficiencies of pten- cells in Dictyostelium. The polarity defects in pten- cells correlate with elevated phosphorylations of PKB substrates. Deletion of AKT orthologue, PkbA, or a subunit of its activator TORC2, reduced the phosphorylations and suppressed the cytokinesis and chemotaxis defects in pten- cells. In these double mutants, the excessive PIP(3) levels and, presumably, activation of other PIP(3)-binding proteins had little or no effect on the cytoskeleton. In bands with increased phosphorylation in pten- cells, we found PKB substrates, PI5K, GefS, GacG, and PakA. Disruption of PakA in pten- cells restored a large fraction of the cells to normal behavior. Consistently, expression of phosphomimetic PakA in pten- cells exacerbated the defects but nonphosphorylatable PakA had no effect. Thus, among many putative PTEN- and PIP(3)-dependent events, phosphorylation of PKB substrates is the key downstream regulator of cell polarity.
Collapse
Affiliation(s)
- Ming Tang
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | | | | | | | | |
Collapse
|
205
|
Cabarcas S, Watabe K, Schramm L. Inhibition of U6 snRNA Transcription by PTEN. ONLINE JOURNAL OF BIOLOGICAL SCIENCES 2010; 10:114-125. [PMID: 21479160 PMCID: PMC3071578 DOI: 10.3844/ojbsci.2010.114.125] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PROBLEM STATEMENT: RNA polymerase III (RNA pol III) is responsible for transcribing many of the small structural RNA molecules involved in RNA processing and protein translation, thereby regulating the growth rate of a cell. RNA pol III transcribes both gene internal (tRNA) and gene external (U6 snRNA) promoters and proper initiation by RNA polymerase III requires the transcription initiation factor TFIIIB. TFIIIB has been shown to be a target of repression by tumor suppressors such as ARF, p53, RB and the RB-related pocket proteins. Also, TFIIIB activity is stimulated by the oncogenes c-Myc and the ERK mitogen-activated protein kinase. Recently, two TFIIIB subunits, BRF1 and BRF2, have been demonstrated to behave as oncogenes, making deregulation of TFIIIB activity and thus RNA pol III transcription an important step in tumor development. PTEN is a commonly mutated tumor suppressor regulating cell growth, proliferation and survival. Thus, we sought to examine the potential role of PTEN in regulating U6 snRNA transcription. APPROACH: We examined the potential for PTEN to regulate U6 snRNA transcription using in vitro RNA pol III luciferase assays, western blotting and deletion analysis in cancer cell lines differing in their PTEN status. RESULTS: Using breast, cervical, prostate and glioblastoma cancer cells we demonstrate: (1) PTEN inhibition of gene external RNA pol III transcription is cell type specific, (2) PTEN-mediated inhibition of U6 transcription occurs via the C2 lipid-binding domain and (3) PTEN repression of U6 transcription occurs, at least in part, through the TFIIIB subunit BRF2. CONCLUSION/RECOMMENDATIONS: Our data demonstrates that regulation of the U6 snRNA gene by PTEN is mediated, in part by the TFIIIB oncogene BRF2, potentially identifying novel targets for chemotherapeutic drug design.
Collapse
Affiliation(s)
- Stephanie Cabarcas
- Department of Biological Sciences, St. John's University, Queens, New York 11439
| | | | | |
Collapse
|
206
|
Sun W, Yang J. Functional mechanisms for human tumor suppressors. J Cancer 2010; 1:136-40. [PMID: 20922055 PMCID: PMC2948218 DOI: 10.7150/jca.1.136] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 09/13/2010] [Indexed: 12/19/2022] Open
Abstract
Tumor suppressors refer to a large group of molecules that are capable of controlling cell division, promoting apoptosis, and suppressing metastasis. The loss of function for a tumor suppressor may lead to cancer due to uncontrolled cell division. Because of their importance, extensive studies have been undertaken to understand the different functional mechanisms of tumor suppressors. Here, we briefly review the four major mechanisms, inhibition of cell division, induction of apoptosis, DNA damage repair, and inhibition of metastasis. It is noteworthy that some tumor suppressors, such as p53, may adopt more than one mechanism for their functions.
Collapse
Affiliation(s)
- Wanpeng Sun
- Drug Design and Discovery Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
| | | |
Collapse
|
207
|
Dong Y, Sui L, Yamaguchi F, Kamitori K, Hirata Y, Hossain MA, Suzuki A, Holley MC, Tokuda M. Phosphatase and tensin homolog deleted on chromosome 10 regulates sensory cell proliferation and differentiation of hair bundles in the mammalian cochlea. Neuroscience 2010; 170:1304-13. [PMID: 20727948 DOI: 10.1016/j.neuroscience.2010.08.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/05/2010] [Accepted: 08/12/2010] [Indexed: 01/16/2023]
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates cell proliferation, differentiation and growth. It regulates neural and glioma stem/progenitor cell renewal and PTEN deletion can drive expansion of epithelial progenitors in the lung, enhancing their capacity for regeneration. Because it is expressed at relatively high levels in developing mammalian auditory hair cells we have analyzed the phenotype of the auditory epithelium in PTEN knock-out mice. PTEN(+/-) heterozygous littermates have only one functional copy of the gene and show clear evidence for haploinsufficiency in the organ of Corti. Auditory sensory epithelial progenitors withdraw from the cell cycle later than in wild-type animals and this is associated with increases in the numbers of both inner and outer hair cells. The cytoskeletal differentiation of hair cells was also affected. While many hair bundles on the hair cells appeared to develop normally, others were structurally disorganized and a number were missing, apparently lost after they had been formed. The results show that PTEN plays a novel role in regulating cell proliferation and differentiation of hair bundles in auditory sensory epithelial cells and suggest that PTEN signaling pathways may provide therapeutic targets for auditory sensory regeneration.
Collapse
Affiliation(s)
- Y Dong
- Department of Cell Physiology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
208
|
Kini V, Chavez A, Mehta D. A new role for PTEN in regulating transient receptor potential canonical channel 6-mediated Ca2+ entry, endothelial permeability, and angiogenesis. J Biol Chem 2010; 285:33082-33091. [PMID: 20705603 DOI: 10.1074/jbc.m110.142034] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Phosphatase and tensin homologue (PTEN) is a dual lipid-protein phosphatase that catalyzes the conversion of phosphoinositol 3,4,5-triphosphate to phosphoinositol 4,5-bisphosphate and thereby inhibits PI3K-Akt-dependent cell proliferation, migration, and tumor vascularization. We have uncovered a previously unrecognized role for PTEN in regulating Ca(2+) entry through transient receptor potential canonical channel 6 (TRPC6) that does not require PTEN phosphatase activity. We show that PTEN tail-domain residues 394-403 permit PTEN to associate with TRPC6. The inflammatory mediator thrombin promotes this association. Deletion of PTEN residues 394-403 prevents TRPC6 cell surface expression and Ca(2+) entry. However, PTEN mutant, C124S, which lacks phosphatase activity, did not alter TRPC6 activity. Thrombin failed to increase endothelial monolayer permeability in the endothelial cells, transducing the Δ394-403 PTEN mutant. Paradoxically, we also show that thrombin failed to induce endothelial cell migration and tube formation in cells transducing the Δ394-403 PTEN mutant. Our results demonstrate that PTEN, through residues 394-403, serves as a scaffold for TRPC6, enabling cell surface expression of the channel. Ca(2+) entry through TRPC6 induces an increase in endothelial permeability and directly promotes angiogenesis. Thus, PTEN is indicated to play a role beyond suppressing PI3K signaling.
Collapse
Affiliation(s)
- Vidisha Kini
- From the Department of Pharmacology and Center for Lung and Vascular Biology, College of Medicine, University of Illinois, Chicago, Illinois 60612
| | - Alejandra Chavez
- From the Department of Pharmacology and Center for Lung and Vascular Biology, College of Medicine, University of Illinois, Chicago, Illinois 60612
| | - Dolly Mehta
- From the Department of Pharmacology and Center for Lung and Vascular Biology, College of Medicine, University of Illinois, Chicago, Illinois 60612.
| |
Collapse
|
209
|
Development of cetuximab-resistant human nasopharyngeal carcinoma cell lines and mechanisms of drug resistance. Biomed Pharmacother 2010; 64:550-8. [PMID: 20630698 DOI: 10.1016/j.biopha.2010.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 03/26/2010] [Indexed: 11/21/2022] Open
Abstract
This work aimed to explore the induction of cetuximab-resistant human nasopharyngeal carcinoma (hNPC) 5-8F/Erbitux cells and the mechanisms of drug resistance. The 5-8F cells with high EGFR expression and cetuximab sensitivity were screened and then induced by stepwise exposure to increasing doses of cetuximab. Western blot was conducted to detect protein levels. Our results are as follows: we successfully induced the cetuximab-resistant 5-8F/Erbitux hNPC cells. After treatment with cetuximab for 3 and 5 days, the RI was 1.2 and 1.1, respectively. The 5-8F/Erbitux cells showed cross-resistance to 5-FU (P<0.01) and some resistance to Taxol (P>0.05) as well as enhanced sensitivity to DDP (P>0.05). The cells had increased levels of P-gP, IGF-1R, P-IGF-1R, K-ras, H-ras, and PTEN protein expression (P<0.001), while survivin decreased (P<0.001). Through sequence alignments, gene mutations in the PTEN gene at exons 5, 7, and 8, as well as the H-ras and K-ras genes in codons 12, 13, 59, and 61, were not observed. After transfection with H-ras-shRNA plasmid, the 5-8F/Erbitux cells showed reduced levels of gene and protein expression of H-ras and elevated sensitivity to cetuximab. In conclusion, gene amplification and overexpression of H-ras was the major mechanism that caused resistance of 5-8F/Erbitux cells to cetuximab, while the overexpression of the H-ras gene was probably associated with the over-activity of the IGF-1R signaling pathway. Gene deletion or mutation of PTEN was not associated with resistance of 5-8F/Erbitux cells to cetuximab.
Collapse
|
210
|
Liu Y, Bankaitis VA. Phosphoinositide phosphatases in cell biology and disease. Prog Lipid Res 2010; 49:201-17. [PMID: 20043944 PMCID: PMC2873057 DOI: 10.1016/j.plipres.2009.12.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 01/10/2023]
Abstract
Phosphoinositides are essential signaling molecules linked to a diverse array of cellular processes in eukaryotic cells. The metabolic interconversions of these phospholipids are subject to exquisite spatial and temporal regulation executed by arrays of phosphatidylinositol (PtdIns) and phosphoinositide-metabolizing enzymes. These include PtdIns- and phosphoinositide-kinases that drive phosphoinositide synthesis, and phospholipases and phosphatases that regulate phosphoinositide degradation. In the past decade, phosphoinositide phosphatases have emerged as topics of particular interest. This interest is driven by the recent appreciation that these enzymes represent primary mechanisms for phosphoinositide degradation, and because of their ever-increasing connections with human diseases. Herein, we review the biochemical properties of six major phosphoinositide phosphatases, the functional involvements of these enzymes in regulating phosphoinositide metabolism, the pathologies that arise from functional derangements of individual phosphatases, and recent ideas concerning the involvements of phosphoinositide phosphatases in membrane traffic control.
Collapse
Affiliation(s)
- Yang Liu
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| | - Vytas A. Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| |
Collapse
|
211
|
Gorbenko O, Panayotou G, Zhyvoloup A, Volkova D, Gout I, Filonenko V. Identification of novel PTEN-binding partners: PTEN interaction with fatty acid binding protein FABP4. Mol Cell Biochem 2010; 337:299-305. [PMID: 19911253 DOI: 10.1007/s11010-009-0312-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 10/29/2009] [Indexed: 02/06/2023]
Abstract
PTEN is a tumor suppressor with dual protein and lipid-phosphatase activity, which is frequently deleted or mutated in many human advanced cancers. Recent studies have also demonstrated that PTEN is a promising target in type II diabetes and obesity treatment. Using C-terminal PTEN sequence in pEG202-NLS as bait, yeast two-hybrid screening on Mouse Embryo, Colon Cancer, and HeLa cDNA libraries was carried out. Isolated positive clones were validated by mating assay and identified through automated DNA sequencing and BLAST database searches. Sequence analysis revealed a number of PTEN-binding proteins linking this phosphatase to a number of different signaling cascades, suggesting that PTEN may perform other functions besides tumor-suppressing activity in different cell types. In particular, the interplay between PTEN function and adipocyte-specific fatty-acid-binding protein FABP4 is of notable interest. The demonstrable tautology of PTEN to FABP4 suggested a role for this phosphatase in the regulation of lipid metabolism and adipocyte differentiation. This interaction was further studied using coimmunoprecipitation and gel-filtration assays. Finally, based on Biacore assay, we have calculated the K(D) of PTEN-FABP4 complex, which is around 2.8 microM.
Collapse
Affiliation(s)
- O Gorbenko
- Department of Cell Signaling, Institute of Molecular Biology and Genetics NASU, Kyiv, Ukraine
| | | | | | | | | | | |
Collapse
|
212
|
Speakman JR, Goran MI. Tissue-specificity and ethnic diversity in obesity-related risk of cancer may be explained by variability in insulin response and insulin signaling pathways. Obesity (Silver Spring) 2010; 18:1071-8. [PMID: 20150900 DOI: 10.1038/oby.2010.16] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Obesity is a predisposing risk factor for several chronic diseases. The link between obesity and cancer appears to be particularly complex. Notably only the risk for development of specific cancers appear to be affected. Moreover, the obesity-related risk of cancer is very different across ethnic groups. African-Americans appear particularly prone, whereas Hispanics appear to be relatively protected. Obesity is associated with increased levels of circulating insulin. These levels of elevated insulin may serve to promote proliferation of fat cells to accommodate the elevated nutrient flux. However, elevated levels of insulin may be a major mediating factor influencing cancer risk. This hypothesis alone cannot explain the complexity of the phenomenon. We suggest here that the different insulin responses to obesity of different ethnic groups may explain their different risk profiles. Moreover, we speculate that tissue-specific variations in the insulin signaling pathways may underlie their differential susceptibility to tumorigenesis in the face of elevated obesity. Elevated cancer risk may be an unwanted side effect of insulin responding to elevated nutrient flux in the obese which it serves to proliferate fat cells that provide a location for storage of ingested fat, which consequently prevents ectopic fat storage. Hence, while Hispanics may be protected from cancer risk in obesity because of their lower insulin response, they have an elevated risk of fatty liver disease. Reduction of insulin levels in obesity as a strategy to reduce cancer risk may pose additional problems unless it is combined also with interventions that aim to limit nutrient influx.
Collapse
Affiliation(s)
- John R Speakman
- Aberdeen Centre for Energy Regulation and Obesity (ACERO), Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
| | | |
Collapse
|
213
|
Suzuki Y, Shirai K, Oka K, Mobaraki A, Yoshida Y, Noda SE, Okamoto M, Suzuki Y, Itoh J, Itoh H, Ishiuchi S, Nakano T. Higher pAkt expression predicts a significant worse prognosis in glioblastomas. JOURNAL OF RADIATION RESEARCH 2010; 51:343-348. [PMID: 20410674 DOI: 10.1269/jrr.09109] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
phosphorylated-Akt (pAkt) plays an important role in tumorigenesis through promotion of cell survival by inhibiting apoptosis and mediating cell proliferation. Higher expression of pAkt has been reported to be associated with an unfavorable prognosis in several malignant tumors. In this study, the prognostic value of pAkt expression was investigated in glioblastomas by using immunohistochemical methods. Tissue sections obtained from 64 patients with glioblastoma were evaluated. The mean and median follow-up period was 16.2 +/- 12.4 and 12 months, respectively (range: from 1 to 62 months). pAkt expression levels were determined by immunohistochemical staining and evaluated for cell positivity. Positive staining was defined when more than 50% of the tumor cells were stained in each section. The correlation between expression of pAkt and overall survival rate was assessed. Glioblastomas showed either or both cytoplasmic and nuclear positive findings for pAkt. A total of 29.7% (19/64) of tissue specimens had greater than 50% positivity. The median survival periods of the patients with pAkt positive and negative tumor were 10 and 14 months, respectively. Two years overall survival rate of the pAkt positive and negative patients were 0% and 24.4%, respectively. Survival rate of the patients with pAkt positive tumor was significantly lower than that of the patients with pAkt negative tumors (p = 0.004). Multivariate analysis showed that extent of surgery was the strongest factor for survival (p = 0.01) and the pAkt expression was the secondly strongest factor (p = 0.06). These results suggest that the higher expression of pAkt the poorer prognosis in patients with glioblastoma.
Collapse
Affiliation(s)
- Yoshiyuki Suzuki
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
214
|
Porta C, Paglino C. Medical treatment of unresectable hepatocellular carcinoma: Going beyond sorafenib. World J Hepatol 2010; 2:103-13. [PMID: 21160981 PMCID: PMC2998959 DOI: 10.4254/wjh.v2.i3.103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 01/14/2010] [Accepted: 01/21/2010] [Indexed: 02/06/2023] Open
Abstract
Even though Sorafenib has radically changed the natural history of those hepatocellular carcinoma patients who are not amenable for curative treatments, further therapeutic improvements are badly needed. As it was for Sorafenib, our increasingly refined understanding of the complex mechanisms underlying HCC carcinogenesis are the starting point for the future development of such treatments. Presently, a number of molecularly targeted agents are in different stages of development for this once orphan cancer. Indeed, several pathways are presently being explored to identify potentially active drugs, including epidermal growth factor receptor, vascular endothelial growth factor/vascular endothelial growth factor receptors, mammalian target of rapamycin, phosphatidyl-inositol-3-kinase/Akt, insulin growth factor, Aurora kinase, Wnt/β-catenin, retinoic acid receptor and hepatocyte growth factor/C-Met. This review is aimed at addressing the results obtained so far with these newer drugs, also considering the challenges we shall face in the near future, including the issue of response evaluation and identification of predictive/prognostic biomarkers.
Collapse
Affiliation(s)
- Camillo Porta
- Camillo Porta, Medical Oncology and Laboratory of Preclinical Oncology and Experimental Therapies, IRCCS San Matteo University Hospital Foundation, Pavia I-27100, Italy
| | | |
Collapse
|
215
|
Chow JYC, Ban M, Wu HL, Nguyen F, Huang M, Chung H, Dong H, Carethers JM. TGF-beta downregulates PTEN via activation of NF-kappaB in pancreatic cancer cells. Am J Physiol Gastrointest Liver Physiol 2010; 298:G275-82. [PMID: 19940030 PMCID: PMC3774494 DOI: 10.1152/ajpgi.00344.2009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
TGF-beta utilizes receptor-activated SMAD signaling to mediate growth suppression; however, non-SMAD signaling that modulates the TGF-beta response in epithelial cells become apparent when the SMAD signaling is abrogated, a common occurrence in pancreatic cancers. Here, we examined whether TGF-beta utilized NF-kappaB to downregulate PTEN, a gene that is rarely mutated in pancreatic cancers. SMAD4-null BxPc3 and CAPAN-1 pancreatic cancer cells were treated with TGF-beta (10 ng/ml) and lysed, and cellular proteins were analyzed by Western blots using p-IkappaB, p65, and PTEN antibodies. PTEN promoter and NF-kappaB activities were assessed by PTEN-luc and p-NF-luc constructs, respectively. Dominant negative p-IkappaB-alpha-M (NF-kappaB superrepressor) was used to block activation of NF-kappaB. Cell motility was assessed by Boyden chamber migration assay. TGF-beta induced IkappaB-alpha phosphorylation followed by NF-kappaB p65 subunit nuclear translocation and increased NF-kappaB activity. IkappaB-alpha-M blocked TGF-beta-induced NF-kappaB activity, reversed downregulated PTEN promoter activity and PTEN expression, and prevented augmentation of cell motility induced by TGF-beta. SMAD4 restoration, but not knockdown of SMAD2 and/or 3, reversed TGF-beta-induced NF-kappaB activity. Thus TGF-beta suppresses PTEN in pancreatic cancer cells through NF-kappaB activation and enhances cell motility and invasiveness in a SMAD4-independent manner that can be counteracted when TGF-beta-SMAD signaling is restored. The TGF-beta/NF-kappaB/PTEN cascade may be a critical pathway for pancreatic cancer cells to proliferate and metastasize.
Collapse
Affiliation(s)
- Jimmy Y. C. Chow
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Makiko Ban
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Helen L. Wu
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Flang Nguyen
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Mei Huang
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Heekyung Chung
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - Hui Dong
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| | - John M. Carethers
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California
| |
Collapse
|
216
|
Muggerud AA, Rønneberg JA, Wärnberg F, Botling J, Busato F, Jovanovic J, Solvang H, Bukholm I, Børresen-Dale AL, Kristensen VN, Sørlie T, Tost J. Frequent aberrant DNA methylation of ABCB1, FOXC1, PPP2R2B and PTEN in ductal carcinoma in situ and early invasive breast cancer. Breast Cancer Res 2010; 12:R3. [PMID: 20056007 PMCID: PMC2880421 DOI: 10.1186/bcr2466] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 12/02/2009] [Accepted: 01/07/2010] [Indexed: 12/27/2022] Open
Abstract
Introduction Ductal carcinoma in situ (DCIS) is a non-invasive lesion of the breast that is frequently detected by mammography and subsequently removed by surgery. However, it is estimated that about half of the detected lesions would never have progressed into invasive cancer. Identifying DCIS and invasive cancer specific epigenetic lesions and understanding how these epigenetic changes are involved in triggering tumour progression is important for a better understanding of which lesions are at risk of becoming invasive. Methods Quantitative DNA methylation analysis of ABCB1, CDKN2A/p16INK4a, ESR1, FOXC1, GSTP1, IGF2, MGMT, MLH1, PPP2R2B, PTEN and RASSF1A was performed by pyrosequencing in a series of 27 pure DCIS, 28 small invasive ductal carcinomas (IDCs), 34 IDCs with a DCIS component and 5 normal breast tissue samples. FOXC1, ABCB1, PPP2R2B and PTEN were analyzed in 23 additional normal breast tissue samples. Real-Time PCR expression analysis was performed for FOXC1. Results Aberrant DNA methylation was observed in all three diagnosis groups for the following genes: ABCB1, FOXC1, GSTP1, MGMT, MLH1, PPP2R2B, PTEN and RASSF1A. For most of these genes, methylation was already present at the DCIS level with the same frequency as within IDCs. For FOXC1 significant differences in methylation levels were observed between normal breast tissue and invasive tumours (P < 0.001). The average DNA methylation levels were significantly higher in the pure IDCs and IDCs with DCIS compared to pure DCIS (P = 0.007 and P = 0.001, respectively). Real-time PCR analysis of FOXC1 expression from 25 DCIS, 23 IDCs and 28 normal tissue samples showed lower gene expression levels of FOXC1 in both methylated and unmethylated tumours compared to normal tissue (P < 0.001). DNA methylation levels of FOXC1, GSTP1, ABCB1 and RASSF1A were higher in oestrogen receptor (ER) positive vs. ER negative tumours; whereas methylation levels of FOXC1, ABCB1, PPP2R2B and PTEN were lower in tumours with a TP53 mutation. Conclusions Quantitative methylation analysis identified ABCB1, FOXC1, PPP2R2B and PTEN as novel genes to be methylated in DCIS. In particular, FOXC1 showed a significant increase in the methylation frequency in invasive tumours. Low FOXC1 gene expression in both methylated and unmethylated DCIS and IDCs indicates that the loss of its expression is an early event during breast cancer progression.
Collapse
Affiliation(s)
- Aslaug Aa Muggerud
- Department of Genetics, Institute for Cancer Research, Oslo University Hospital Radiumhospitalet, Montebello, Oslo, N-0310, Norway
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
217
|
Henson SM, Akbar AN. Memory T-Cell Homeostasis and Senescence during Aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 684:189-97. [DOI: 10.1007/978-1-4419-6451-9_15] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
218
|
Nardella C, Carracedo A, Salmena L, Pandolfi PP. Faithfull modeling of PTEN loss driven diseases in the mouse. Curr Top Microbiol Immunol 2010; 347:135-68. [PMID: 20549475 DOI: 10.1007/82_2010_62] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A decade of work has indisputably defined PTEN as a pivotal player in human health and disease. Above all, PTEN has been identified as one of the most commonly lost or mutated tumor suppressor genes in human cancers. For this reason, the generation of a multitude of mouse models has been an invaluable strategy to dissect the function and consequences-of-loss of this essential, evolutionary conserved lipid phosphatase in tumor initiation and progression.In this chapter, we will summarize the mouse models that have allowed us to faithfully recapitulate features of human cancers and to highlight the network of connections between the PTEN signaling cascade and other oncogenic or tumor suppressive pathways.Notably, PTEN represents one of the most extensively modeled genes involved in human cancer and exemplifies the strength of genetic mouse modeling as an approach to gain information aimed to improve our understanding of and ability to alleviate human disease.
Collapse
Affiliation(s)
- Caterina Nardella
- Department of Medicine and Pathology, Harvard Medical School, Boston, MA 02215, USA
| | | | | | | |
Collapse
|
219
|
Diggelmann HR, Van Daele DJ, O'Dorisio TM, Hoffman HT. Insular thyroid carcinoma in a patient with Cowden syndrome. Laryngoscope 2009; 120:454-7. [PMID: 20025044 DOI: 10.1002/lary.20507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cowden syndrome is an autosomal dominant disorder characterized by benign and malignant hamartomatous lesions that can develop from all three germ cell derivatives. This disorder predisposes patients to develop malignant tumors of the breast, endometrium, and thyroid. We present a patient with clinically relevant manifestations of Cowden syndrome, with genetic verification, impacting by way of airway compromise due to hamartomas, urinary tract abnormalities, and insular thyroid cancer. This case illustrates the value of recognizing Cowden syndrome at an earlier stage when the patient could have received appropriate management to decrease the morbidity of untreated hamartomatous growths, and an elective thyroidectomy would have been a viable option to manage his malignancy. Through this case report, we provide further insight into management of this disorder.
Collapse
Affiliation(s)
- Henry R Diggelmann
- Department of Otolaryngology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA
| | | | | | | |
Collapse
|
220
|
Abstract
HER2 is a transmembrane oncoprotein encoded by the HER2/neu gene and is overexpressed in approximately 20 to 25% of invasive breast cancers. It can be therapeutically targeted by trastuzumab, a humanized IgG1 kappa light chain monoclonal antibody. Although trastuzumab is currently considered one of the most effective treatments in oncology, a significant number of patients with HER2-overexpressing breast cancer do not benefit from it. Understanding the mechanisms of action and resistance to trastuzumab is therefore crucial for the development of new therapeutic strategies. This review discusses proposed trastuzumab mode of action as well as proposed mechanisms for resistance. Mechanisms for resistance are grouped into four main categories: (1) obstacles preventing trastuzumab binding to HER2; (2) upregulation of HER2 downstream signaling pathways; (3) signaling through alternate pathways; and (4) failure to trigger an immune-mediated mechanism to destroy tumor cells. These potential mechanisms through which trastuzumab resistance may arise have been used as a guide to develop drugs, presently in clinical trials, to overcome resistance. The mechanisms conferring trastuzumab resistance, when completely understood, will provide insight on how best to treat HER2-overexpressing breast cancer. The understanding of each mechanism of resistance is therefore critical for the educated development of strategies to overcome it, as well as for the development of tools that would allow definitive and efficient patient selection for each therapy. (Clin Cancer Res 2009;15(24):7479-91).
Collapse
Affiliation(s)
- Paula R. Pohlmann
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ingrid A. Mayer
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
- Breast Cancer Research Program, Vanderbilt-Ingram Comprehensive Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ray Mernaugh
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
| |
Collapse
|
221
|
Moulos P, Papadodima O, Chatziioannou A, Loutrari H, Roussos C, Kolisis FN. A transcriptomic computational analysis of mastic oil-treated Lewis lung carcinomas reveals molecular mechanisms targeting tumor cell growth and survival. BMC Med Genomics 2009; 2:68. [PMID: 20003503 PMCID: PMC2801511 DOI: 10.1186/1755-8794-2-68] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 12/15/2009] [Indexed: 12/17/2022] Open
Abstract
Background Mastic oil from Pistacia lentiscus variation chia, a blend of bioactive terpenes with recognized medicinal properties, has been recently shown to exert anti-tumor growth activity through inhibition of cancer cell proliferation, survival, angiogenesis and inflammatory response. However, no studies have addressed its mechanisms of action at genome-wide gene expression level. Methods To investigate molecular mechanisms triggered by mastic oil, Lewis Lung Carcinoma cells were treated with mastic oil or DMSO and RNA was collected at five distinct time points (3-48 h). Microarray expression profiling was performed using Illumina mouse-6 v1 beadchips, followed by computational analysis. For a number of selected genes, RT-PCR validation was performed in LLC cells as well as in three human cancer cell lines of different origin (A549, HCT116, K562). PTEN specific inhibition by a bisperovanadium compound was applied to validate its contribution to mastic oil-mediated anti-tumor growth effects. Results In this work we demonstrated that exposure of Lewis lung carcinomas to mastic oil caused a time-dependent alteration in the expression of 925 genes. GO analysis associated expression profiles with several biological processes and functions. Among them, modifications on cell cycle/proliferation, survival and NF-κB cascade in conjunction with concomitant regulation of genes encoding for PTEN, E2F7, HMOX1 (up-regulation) and NOD1 (down-regulation) indicated some important mechanistic links underlying the anti-proliferative, pro-apoptotic and anti-inflammatory effects of mastic oil. The expression profiles of Hmox1, Pten and E2f7 genes were similarly altered by mastic oil in the majority of test cancer cell lines. Inhibition of PTEN partially reversed mastic oil effects on tumor cell growth, indicating a multi-target mechanism of action. Finally, k-means clustering, organized the significant gene list in eight clusters demonstrating a similar expression profile. Promoter analysis in a representative cluster revealed shared putative cis-elements suggesting a common regulatory transcription mechanism. Conclusions Present results provide novel evidence on the molecular basis of tumor growth inhibition mediated by mastic oil and set a rational basis for application of genomics and bioinformatic methodologies in the screening of natural compounds with potential cancer chemopreventive activities.
Collapse
Affiliation(s)
- Panagiotis Moulos
- Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Athens, Greece.
| | | | | | | | | | | |
Collapse
|
222
|
Porta C, Figlin RA. Phosphatidylinositol-3-kinase/Akt signaling pathway and kidney cancer, and the therapeutic potential of phosphatidylinositol-3-kinase/Akt inhibitors. J Urol 2009; 182:2569-77. [PMID: 19836781 DOI: 10.1016/j.juro.2009.08.085] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Indexed: 11/17/2022]
Abstract
PURPOSE The PI3K/Akt signaling pathway is activated by many cellular stimuli. It regulates fundamental cellular functions, including transcription, translation, proliferation, growth and survival. It also closely interacts with many other key pathways such as mTOR and, thus, is linked to angiogenesis. Disturbed activation of the PI3K/Akt pathway is associated with many human malignancies. We reviewed the available literature on PI3K/Akt and PI3K/Akt targeting drugs for renal cell carcinoma. MATERIALS AND METHODS MEDLINE and the proceedings of the main oncological meetings were extensively searched to identify the available literature on the role of this pathway in renal cell carcinoma pathogenesis, and on preclinical and clinical activity of compounds specifically targeting this pathway. Clinical data and perspectives on several compounds at different stages of development were also reviewed. RESULTS Cumulative evidence links PI3K/Akt alterations with renal cell carcinoma. Thus, renal cell carcinoma is an ideal setting in which to test compounds specifically targeting this pathway. Several PI3K/Akt inhibitors are currently under preclinical and early clinical development as anticancer agents but only perifosine (Keryx Biopharmaceuticals, New York, New York) appears to be at a more advanced stage, having been tested with promising results alone or combined with other molecularly targeted agents. CONCLUSIONS The PI3K/Akt pathway has a pivotal role in renal cell carcinoma pathogenesis and, thus, represents an ideal target for therapeutic intervention. Of the several compounds in early phases of development only perifosine has already proved to be clinically active. Thus, it should be considered an extremely interesting drug to be used alone or in combination.
Collapse
Affiliation(s)
- Camillo Porta
- Medical Oncology and Laboratory of Pre-Clinical Oncology and Developmental Therapeutics, Istituto Di Ricovero e Cura a Carattere Scientifico San Matteo University Hospital Foundation, Pavia, Italy.
| | | |
Collapse
|
223
|
Fan C, He L, Kapoor A, Rybak AP, De Melo J, Cutz JC, Tang D. PTEN inhibits BMI1 function independently of its phosphatase activity. Mol Cancer 2009; 8:98. [PMID: 19903340 PMCID: PMC2777864 DOI: 10.1186/1476-4598-8-98] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 11/10/2009] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND PTEN is the second most mutated tumor suppressor gene other than p53. It suppresses tumorigenesis by dephosphorylating phosphatidylinositol (3,4,5)-triphosphate (PIP3) to phosphatidylinositol (4,5)-biphosphate (PIP2), thereby directly inhibiting phosphatidylinositol 3 kinase (PI3K)-mediated tumorigenic activities. Consistent with this model of action, cytosolic PTEN is recruited to the plasma membrane to dephosphorylate PIP3. While nuclear PTEN has been shown to suppress tumorigenesis by governing genome integrity, additional mechanisms may also contribute to nuclear PTEN-mediated tumor suppression. The nuclear protein BMI1 promotes stem cell self-renewal and tumorigenesis and PTEN inhibits these events, suggesting that PTEN may suppress BMI1 function. RESULTS We investigated whether PTEN inhibits BMI1 function during prostate tumorigenesis. PTEN binds to BMI1 exclusively in the nucleus. This interaction does not require PTEN's phosphatase activity, as phosphatase-deficient PTEN mutants, PTEN/C124S (CS), PTEN/G129E (GE), and a C-terminal PTEN fragment (C-PTEN) excluding the catalytic domain, all associate with BMI1. Furthermore, the residues 186-286 of C-PTEN are sufficient for binding to BMI1. This interaction reduces BMI1's function. BMI1 enhances hTERT activity and reduces p16(INK4A) and p14(ARF) expression. These effects were attenuated by PTEN, PTEN(CS), PTEN(GE), and C-PTEN. Furthermore, knockdown of PTEN in DU145 cells increased hTERT promoter activity, which was reversed when BMI1 was concomitantly knocked-down, indicating that PTEN reduces hTERT promoter activity via inhibiting BMI1 function. Conversely, BMI1 reduces PTEN's ability to inhibit AKT activation, which can be attributed to its interaction with PTEN in the nucleus, making PTEN unavailable to dephosphorylate membrane-bound PIP3. Furthermore, BMI1 appears to co-localize with PTEN more frequently in clinical prostate tissue samples from patients diagnosed with PIN (prostatic intraepithelial neoplasia) and carcinoma compared to normal prostate epithelium. While PTEN co-localized with BMI1 in 2.4% of normal prostate epithelial cells, co-localization was observed in 37.6% and 18.5% of cells in PIN and carcinoma, respectively. Collectively, we demonstrate that PTEN inhibits BMI1 function via binding to BMI1 in a phosphatase independent manner. CONCLUSION We demonstrate that nuclear PTEN reduces BMI1 function independently of its phosphatase activity. It was recently observed that nuclear PTEN also suppresses tumorigenesis. Our results, therefore, provide a plausible mechanism by which nuclear PTEN prevents tumorigenesis.
Collapse
Affiliation(s)
- Catherine Fan
- Division of Nephrology, Department of Medicine, McMaster University, McMaster University, Hamilton, ON, Canada.
| | | | | | | | | | | | | |
Collapse
|
224
|
Palmieri G, Capone M, Ascierto ML, Gentilcore G, Stroncek DF, Casula M, Sini MC, Palla M, Mozzillo N, Ascierto PA. Main roads to melanoma. J Transl Med 2009; 7:86. [PMID: 19828018 PMCID: PMC2770476 DOI: 10.1186/1479-5876-7-86] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 10/14/2009] [Indexed: 12/12/2022] Open
Abstract
The characterization of the molecular mechanisms involved in development and progression of melanoma could be helpful to identify the molecular profiles underlying aggressiveness, clinical behavior, and response to therapy as well as to better classify the subsets of melanoma patients with different prognosis and/or clinical outcome. Actually, some aspects regarding the main molecular changes responsible for the onset as well as the progression of melanoma toward a more aggressive phenotype have been described. Genes and molecules which control either cell proliferation, apoptosis, or cell senescence have been implicated. Here we provided an overview of the main molecular changes underlying the pathogenesis of melanoma. All evidence clearly indicates the existence of a complex molecular machinery that provides checks and balances in normal melanocytes. Progression from normal melanocytes to malignant metastatic cells in melanoma patients is the result of a combination of down- or up-regulation of various effectors acting on different molecular pathways.
Collapse
Affiliation(s)
- Giuseppe Palmieri
- Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche (CNR), Sassari, Italy.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
225
|
Liu Y, Boukhelifa M, Tribble E, Bankaitis VA. Functional studies of the mammalian Sac1 phosphoinositide phosphatase. ACTA ACUST UNITED AC 2009; 49:75-86. [PMID: 19534026 DOI: 10.1016/j.advenzreg.2009.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yang Liu
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA
| | | | | | | |
Collapse
|
226
|
Abstract
In humans and other mammalian species, the pool of resting primordial follicles serves as the source of developing follicles and fertilizable ova for the entire length of female reproductive life. One question that has intrigued biologists is: what are the mechanisms controlling the activation of dormant primordial follicles. Studies from previous decades have laid a solid, but yet incomplete, foundation. In recent years, molecular mechanisms underlying follicular activation have become more evident, mainly through the use of genetically modified mouse models. As hypothesized in the 1990s, the pool of primordial follicles is now known to be maintained in a dormant state by various forms of inhibitory machinery, which are provided by several inhibitory signals and molecules. Several recently reported mutant mouse models have shown that a synergistic and coordinated suppression of follicular activation provided by multiple inhibitory molecules is necessary to preserve the dormant follicular pool. Loss of function of any of the inhibitory molecules for follicular activation, including PTEN (phosphatase and tensin homolog deleted on chromosome 10), Foxo3a, p27, and Foxl2, leads to premature and irreversible activation of the primordial follicle pool. Such global activation of the primordial follicle pool leads to the exhaustion of the resting follicle reserve, resulting in premature ovarian failure in mice. In this review, we summarize both historical and recent results on mammalian primordial follicular activation and focus on the up-to-date knowledge of molecular networks controlling this important physiological event. We believe that information obtained from mutant mouse models may also reflect the molecular machinery responsible for follicular activation in humans. These advances may provide a better understanding of human ovarian physiology and pathophysiology for future clinical applications.
Collapse
Affiliation(s)
- Deepak Adhikari
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | | |
Collapse
|
227
|
Belfiore A, Genua M, Malaguarnera R. PPAR-γ agonists and their effects on IGF-I receptor signaling: Implications for cancer. PPAR Res 2009; 2009:830501. [PMID: 19609453 PMCID: PMC2709717 DOI: 10.1155/2009/830501] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2009] [Accepted: 05/04/2009] [Indexed: 01/04/2023] Open
Abstract
It is now well established that the development and progression of a variety of human malignancies are associated with dysregulated activity of the insulin-like growth factor (IGF) system. In this regard, promising drugs have been developed to target the IGF-I receptor or its ligands. These therapies are limited by the development of insulin resistance and compensatory hyperinsulinemia, which in turn, may stimulate cancer growth. Novel therapeutic approaches are, therefore, required. Synthetic PPAR-γ agonists, such as thiazolidinediones (TZDs), are drugs universally used as antidiabetic agents in patients with type 2 diabetes. In addition of acting as insulin sensitizers, PPAR-γ agonists mediate in vitro and in vivo pleiotropic anticancer effects. At least some of these effects appear to be linked with the downregulation of the IGF system, which is induced by the cross-talk of PPAR-γ agonists with multiple components of the IGF system signaling. As hyperinsulinemia is an emerging cancer risk factor, the insulin lowering action of PPAR-γ agonists may be expected to be also beneficial to reduce cancer development and/or progression. In light of these evidences, TZDs or other PPAR-γ agonists may be exploited in those tumors "addicted" to the IGF signaling and/or in tumors occurring in hyperinsulinemic patients.
Collapse
Affiliation(s)
- A Belfiore
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Catanzaro, 88100 Catanzaro, Italy.
| | | | | |
Collapse
|
228
|
Uner AH, Sağlam A, Han U, Hayran M, Sungur A, Ruacan S. PTEN and p27 expression in mature T-cell and NK-cell neoplasms. Leuk Lymphoma 2009; 46:1463-70. [PMID: 16194892 DOI: 10.1080/10428190500144813] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PTEN is a tumor suppressor gene located on chromosome 10q23 and is amongst the most commonly mutated genes in human cancers. The lipid phosphatase activity of Pten enables it to dephosphorylate PIP3, thereby antagonizing growth factor stimulated PI3-kinase signaling mediated by AKT/PKB. The growth inhibition effect of PTEN has been shown to be mediated by p27 which is one of the important effector molecules downstream of the AKT pathway. Recently the importance of the Pten and AKT pathway in the regulation of the immune system and development of hematological malignancies has been shown. Loss of Pten and p27 expressions were examined immunohistochemically in 45 patients with peripheral T- and NK-cell lymphoma. Partial or complete loss of Pten was detected in 66.7% of the cases of anaplastic large cell lymphoma (ALCL) compared to only 12.5% of all other mature T-/NK-cell lymphomas combined. Loss of p27 was identified in 64.9% of cases, which showed a positive correlation with Pten loss. In this study, we showed that loss of Pten is more frequent in ALCL as compared to other mature T-/NK-cell lymphomas, which strongly correlates with the loss of p27 expression. Our findings provide further evidence for the importance of the deregulation of the PI3K-AKT pathway in ALCL.
Collapse
Affiliation(s)
- Ayşegül H Uner
- Department of Pathology, Hacettepe University Medical Faculty, Sihhiye, Ankara, Turkey.
| | | | | | | | | | | |
Collapse
|
229
|
Ligresti G, Militello L, Steelman LS, Cavallaro A, Basile F, Nicoletti F, Stivala F, McCubrey JA, Libra M. PIK3CA mutations in human solid tumors: role in sensitivity to various therapeutic approaches. Cell Cycle 2009; 8:1352-8. [PMID: 19305151 DOI: 10.4161/cc.8.9.8255] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphatidylinositol 3-kinases (PI3Ks) are a group of lipid kinases that regulate signaling pathways involved in cell proliferation, adhesion, survival and motility. The PI3K pathway is considered to play an important role in tumorigenesis. Activating mutations of the p110alpha subunit of PI3K (PIK3CA) have been identified in a broad spectrum of tumors. Analyses of PIK3CA mutations reveals that they increase the PI3K signal, stimulate downstream Akt signaling, promote growth factor-independent growth and increase cell invasion and metastasis. In this review, we analyze the contribution of the PIK3CA mutations in cancer, and their possible implications for diagnosis and therapy.
Collapse
Affiliation(s)
- Giovanni Ligresti
- Department of Biomedical Sciences, University of Catania, Catania, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
230
|
Improving the prognosis for patients with glioblastoma: the rationale for targeting Src. J Neurooncol 2009; 95:151-163. [PMID: 19436954 DOI: 10.1007/s11060-009-9916-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 04/30/2009] [Indexed: 01/08/2023]
Abstract
Glioblastoma is the most common and aggressive form of primary brain tumor. The prognosis for patients diagnosed with glioblastoma is poor, with a median survival of 12-14 months and a 5-year survival rate of <5%. The upfront standard treatment for patients with newly diagnosed glioblastoma, consisting of surgery followed by chemotherapy combined with radiotherapy, provides only short-term survival benefits. Recurrent glioblastoma is an extremely challenging therapeutic setting because of the aggressive and resistant nature of the tumor. A set of key molecular targets in oncology is the Src family of non-receptor protein kinases. Dysregulated signaling via the Src kinases has been shown to underlie glioma-related proliferation, angiogenesis, migration, and survival. Here we review the biologic role of Src in malignant glioma and discuss key preclinical studies demonstrating the potential utility of inhibiting Src in glioma. Proof of clinical benefit is forthcoming from the first clinical studies involving the newest generation of small molecule Src inhibitors currently in clinical trials for recurrent glioblastoma. Blocking Src alone will likely not translate into a significant clinical benefit; thus, strategies for combining Src inhibitors with potential synergistic therapeutic modalities will be discussed. This review will focus on dasatinib, the most advanced Src inhibitor being tested in glioblastoma, which is currently in phase I/II trials in this setting.
Collapse
|
231
|
Ma J, Sawai H, Ochi N, Matsuo Y, Xu D, Yasuda A, Takahashi H, Wakasugi T, Takeyama H. PTEN regulates angiogenesis through PI3K/Akt/VEGF signaling pathway in human pancreatic cancer cells. Mol Cell Biochem 2009; 331:161-71. [PMID: 19437103 DOI: 10.1007/s11010-009-0154-x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Accepted: 04/28/2009] [Indexed: 02/06/2023]
Abstract
Phosphoinositide 3-kinase (PI3K) pathway exerts its effects through Akt, its downstream target molecule, and thereby regulates various cell functions including cell proliferation, cell transformation, apoptosis, tumor growth, and angiogenesis. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been implicated in regulating cell survival signaling through the PI3K/Akt pathway. However, the mechanism by PI3K/PTEN signaling regulates angiogenesis and tumor growth in vivo remains to be elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in tumor angiogenesis. The effect of PTEN on VEGF-mediated signal in pancreatic cancer is unknown. This study aimed to determine the effect of PTEN on both the expression of VEGF and angiogenesis. Toward that end, we used the siRNA knockdown method to specifically define the role of PTEN in the expression of VEGF and angiogenesis. We found that siRNA-mediated inhibition of PTEN gene expression in pancreatic cancer cells increase their VEGF secretion, up-modulated the proliferation, and migration of co-cultured vascular endothelial cell and enhanced tubule formation by HUVEC. In addition, PTEN modulated VEGF-mediated signaling and affected tumor angiogenesis through PI3K/Akt/VEGF/eNOS pathway.
Collapse
Affiliation(s)
- Jiachi Ma
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Science, Kawasumi 1, Mizuho-cho, Mizuhoku, Nagoya, 467-8601, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
232
|
Beloueche-Babari M, Peak JC, Jackson LE, Tiet MY, Leach MO, Eccles SA. Changes in choline metabolism as potential biomarkers of phospholipase C{gamma}1 inhibition in human prostate cancer cells. Mol Cancer Ther 2009; 8:1305-11. [PMID: 19417158 DOI: 10.1158/1535-7163.mct-09-0039] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Phosphoinositide-specific phospholipase Cγ1 (PLCγ1) is activated downstream of many receptor tyrosine kinases to promote cell motility. Inhibition of this protein is being explored as a therapeutic strategy for blocking cancer cell invasion and metastasis. The clinical development of such cytostatic therapies requires the implementation of pharmacodynamic biomarkers of target modulation. In this study, we use magnetic resonance spectroscopy to explore metabolic biomarkers of PLCγ1 down-regulation in PC3LN3 prostate cancer cells. We show that inhibition of PLCγ1 via an inducible short hairpin RNA system causes a reduction in phosphocholine levels by up to 50% relative to the control as detected by (1)H and (31)P magnetic resonance spectroscopy analyses. This correlated with a rounded-up morphology and reduced cell migration. Interestingly, the fall in phosphocholine levels was not recorded in cells with constitutive PLCγ1 knockdown where the rounded-up phenotype was no longer apparent. This study reveals alterations in metabolism that accompany the cellular effects of PLCγ1 knockdown and highlights phosphocholine as a potential pharmacodynamic biomarker for monitoring the action of inhibitors targeting PLCγ1 signaling.
Collapse
Affiliation(s)
- Mounia Beloueche-Babari
- Cancer Research UK Clinical Magnetic Resonance Research Group, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom.
| | | | | | | | | | | |
Collapse
|
233
|
Cai QY, Chen XS, Zhong SC, Luo X, Yao ZX. Differential Expression of PTEN in Normal Adult Rat Brain and Upregulation of PTEN and p-Akt in the Ischemic Cerebral Cortex. Anat Rec (Hoboken) 2009; 292:498-512. [DOI: 10.1002/ar.20834] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
234
|
Abstract
Dysregulated activity of phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin complex 1 (mTORC1) is characteristic feature of hamartoma syndromes. Hamartoma syndromes, dominantly inherited cancer predisposition disorders, affect multiple organs and are manifested by benign tumors consisting of various cell types native to the tissues in which they arise. In the past few years, three inherited hamartoma syndromes, Cowden syndrome (CS), tuberous sclerosis complex (TSC) syndrome, and Peutz-Jeghens syndrome (PJS), have all been linked to a common biochemical pathway: the hyperactivation of PI3K/mTORC1 intracellular signaling. Three tumor suppressors, PTEN (phosphatases and tensin homolog), tuberous sclerosis complex TSC1/TSC2, and LKB1, are negative regulators of PI3K/mTORC1 signaling; disease-related inactivation of these tumor suppressors results in the development of PTEN-associated hamartoma syndromes, TSC and PJS, respectively. The goal of this review is to provide a roadmap for navigating the inherently complex regulation of PI3K/mTORC1 signaling while highlighting the progress that has been made in elucidating the cellular and molecular mechanisms of hamartoma syndromes and identificating potential therapeutic targets for their treatment. Importantly, because the PI3K/mTORC1 pathway is activated in the majority of common human cancers, the identification of novel molecular target(s) for the treatment of hamartoma syndromes may have a broader translational potential, and is critically important not only for therapeutic intervention in hamartoma disorders, but also for the treatment of cancers.
Collapse
Affiliation(s)
- Vera P Krymskaya
- Department of Medicine, and Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104-3403, USA.
| | | |
Collapse
|
235
|
|
236
|
Hamaï A, Meslin F, Benlalam H, Jalil A, Mehrpour M, Faure F, Lecluse Y, Vielh P, Avril MF, Robert C, Chouaib S. ICAM-1 has a critical role in the regulation of metastatic melanoma tumor susceptibility to CTL lysis by interfering with PI3K/AKT pathway. Cancer Res 2009; 68:9854-64. [PMID: 19047166 DOI: 10.1158/0008-5472.can-08-0719] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human primary melanoma cells (T1) were found to be more susceptible to lysis by a Melan-A/MART-1-specific CTL clone (LT12) than their metastatic derivative (G1). We show that this differential susceptibility does not involve antigen presentation by target cells, synapse formation between the metastatic target and CTL clone, or subsequent granzyme B (GrB) polarization. Although PI-9, an inhibitor of GrB, was found to be overexpressed in metastatic G1 cells, knockdown of the PI-9 gene did not result in the attenuation of G1 resistance to CTL-induced killing. Interestingly, we show that whereas T1 cells express high levels of intercellular adhesion molecule-1 (ICAM-1), a dramatically reduced expression was noted on G1 cells. We also showed that sorted ICAM-1+ G1 cells were highly sensitive to CTL-induced lysis compared with ICAM-1- G1 cells. Furthermore, incubation of metastatic G1 cells with IFN-gamma resulted in the induction of ICAM-1 and the potentiation of their susceptibility to lysis by LT12. More importantly, we found that the level of ICAM-1 expression by melanoma cells correlated with decreased PTEN activity. ICAM-1 knockdown in T1 cells resulted in increased phosphorylation of PTEN and the subsequent activation of AKT. We have additionally shown that inhibition of the phosphatidylinositol (3,4,5)-triphosphate kinase (PI3K)/AKT pathway by the specific inhibitor wortmannin induced a significant potentiation of susceptibility of G1 and ICAM-1 small interfering RNA-treated T1 cells to CTL-induced lysis. The present study shows that a shift in ICAM-1 expression, which was associated with an activation of the PI3K/AKT pathway, can be used by metastatic melanoma cells to escape CTL-mediated killing.
Collapse
Affiliation(s)
- Ahmed Hamaï
- Institut National de la Santé et de la Recherche Médicale, U753, Laboratoire d'Immunologie des Tumeurs Humaines: Interaction effecteurs cytotoxiques-système tumoral, Institut Gustave Roussy PR1 and IFR 54, Villejuif, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
237
|
Kang I, Kum YS, Park KK, Kim DY, Park JS. Clinical Significance of PTEN and Ki-67 Expression in Prostate Cancer. Korean J Urol 2009. [DOI: 10.4111/kju.2009.50.6.560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Il Kang
- Department of Urology, College of Medicine, Daegu Catholic University, Daegu, Korea
| | - Yoon Seup Kum
- Department of Pathology, College of Medicine, Daegu Catholic University, Daegu, Korea
| | - Kwan Kyu Park
- Department of Pathology, College of Medicine, Daegu Catholic University, Daegu, Korea
| | - Duk Yoon Kim
- Department of Urology, College of Medicine, Daegu Catholic University, Daegu, Korea
| | - Jae Shin Park
- Department of Urology, College of Medicine, Daegu Catholic University, Daegu, Korea
| |
Collapse
|
238
|
Akt2 overexpression plays a critical role in the establishment of colorectal cancer metastasis. Proc Natl Acad Sci U S A 2008; 105:20315-20. [PMID: 19075230 DOI: 10.1073/pnas.0810715105] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Understanding the distinct genetic and epigenetic changes contributing to the establishment and growth of metastatic lesions is crucial for the development of novel therapeutic strategies. In a search for key regulators of colorectal cancer metastasis establishment, we have found that the serine/threonine kinase Akt2, a known proto-oncogene, is highly expressed in late-stage colorectal cancer and metastatic tumors. Suppression of Akt2 expression in highly metastatic colorectal carcinoma cells inhibits their ability to metastasize in an experimental liver metastasis model. Overexpression of wild-type Akt1 did not restore metastatic potential in cells with downregulated Akt2, thus suggesting non-redundant roles for the individual Akt isoforms. In contrast, Akt2 overexpression in wild-type PTEN expressing SW480 colorectal cancer cells led to the formation of micrometastases; however, loss of PTEN is required for sustained formation of overt metastasis. Finally, we found that the consequence of PTEN loss and Akt2 overexpression function synergistically to promote metastasis. These results support a role for Akt2 overexpression in metastatic colorectal cancer and establish a mechanistic link between Akt2 overexpression and PTEN mutation in metastatic tumor establishment and growth. Taken together, these data suggest that Akt family members have distinct functional roles in tumor progression and that selective targeting of the PI3K/Akt2 pathway may provide a novel treatment strategy for colorectal cancer metastasis.
Collapse
|
239
|
Plasminogen activator inhibitor 1 protects fibrosarcoma cells from etoposide-induced apoptosis through activation of the PI3K/Akt cell survival pathway. Neoplasia 2008; 10:1083-91. [PMID: 18813358 DOI: 10.1593/neo.08486] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/26/2008] [Accepted: 06/27/2008] [Indexed: 11/18/2022] Open
Abstract
High levels of plasminogen activator inhibitor (PAI-1) in tumors are associated with poor prognosis in several cancer types, and the reason for this association is not fully understood. Plasminogen activator inhibitor 1 has been suggested to contribute to tumor growth by protecting cancer cells from apoptosis, and we have previously shown that wild type murine fibrosarcoma cells are significantly more resistant to apoptosis induced by chemotherapy than PAI-1-deficient fibrosarcoma cells. Here, we further investigated the molecular mechanisms underlying the antiapoptotic function of PAI-1 focusing on the phosphatidylinositol 3-phosphate kinase (PI3K)/Akt cell survival pathway. We demonstrate that the activation level of the Akt cell survival pathway is reduced in PAI-1-deficient cells. Inhibition of either PI3K or Akt by synthetic inhibitors sensitized the wild type but not the PAI-1-deficient cells to etoposide-induced cell death. More importantly, reintroduction of PAI-1 expression in PAI-1-deficient cells induced an increase in Akt activity and protection against etoposide-induced apoptosis. Concordantly, silencing of PAI-1 by RNA interference in wild type fibrosarcoma cells decreased the level of active Akt, and this was accompanied by a sensitization of the cells to etoposide-induced cell death. Altogether, our data suggest that PAI-1 influences sensitivity to etoposide-induced apoptosis through the PI3K/Akt cell survival pathway by acting upstream of PI3K and Akt. This points to PAI-1 as a possible therapeutic target in cancer diseases where PAI-1 inhibits chemotherapy-induced apoptosis.
Collapse
|
240
|
McPhee TR, McDonald PC, Oloumi A, Dedhar S. Integrin-linked kinase regulates E-cadherin expression through PARP-1. Dev Dyn 2008; 237:2737-47. [PMID: 18773488 DOI: 10.1002/dvdy.21685] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Repression of E-cadherin expression by the transcription factor, Snail, is implicated in epithelial to mesenchymal transition and cancer progression. We show here that Integrin-Linked Kinase (ILK) regulates E-cadherin expression through Poly(ADP-ribose) polymerase-1 (PARP-1). ILK overexpression in Scp2 cells resulted in stimulation of Snail expression and loss of E-cadherin expression. Silencing of ILK, Akt or Snail resulted in re-expression of E-cadherin in PC3 cells. To elucidate the signaling pathway downstream of ILK, we identified candidate Snail promoter ILK Responsive Element (SIRE) binding proteins. PARP-1 was identified as a SIRE-binding protein. ILK silencing inhibited binding of PARP-1 to SIRE. PARP-1 silencing resulted in inhibition of Snail and ZEB1, leading to up-regulation of E-cadherin. We suggest a model in which ILK represses E-cadherin expression by regulating PARP-1, leading to the binding of PARP-1 to SIRE and modulation of Snail expression.
Collapse
Affiliation(s)
- Timothy R McPhee
- Genetics Graduate Program, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | | | | | | |
Collapse
|
241
|
Semba S, Satake S, Matsushita M, Yokozaki H. Phosphatase activity of nuclear PTEN is required for CDX2-mediated intestinal differentiation of gastric carcinoma. Cancer Lett 2008; 274:143-50. [PMID: 18996641 DOI: 10.1016/j.canlet.2008.09.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 07/02/2008] [Accepted: 09/09/2008] [Indexed: 12/13/2022]
Abstract
The PTEN tumor suppressor localizes predominantly to the cytoplasm, where it negatively regulates the phosphatidylinositol 3-kinase-AKT signaling pathway; however, the biological significance of nuclear PTEN in gastric carcinoma (GC) remains unknown. In this study, transduction of recombinant PTEN into GC-derived TMK-1 cells promoted PTEN nuclear localization with increased mRNA levels of CDX2 and intestinal claudins (CLDN3 and CLDN4), whereas the G129E phosphatase 'dead' mutant had no effect. In GC tissue samples, tumors with nuclear PTEN expression frequently demonstrated the intestinal-type claudin phenotype. Our results suggested that nuclear localization of PTEN is important for determining intestinal differentiation of GCs.
Collapse
Affiliation(s)
- Shuho Semba
- Division of Pathology, Department of Pathology and Microbiology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
| | | | | | | |
Collapse
|
242
|
Wang X, Jiang X. PTEN: a default gate-keeping tumor suppressor with a versatile tail. Cell Res 2008; 18:807-16. [PMID: 18626510 DOI: 10.1038/cr.2008.83] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The tumor suppressor PTEN controls a variety of biological processes including cell proliferation, growth, migration, and death. As a master cellular regulator, PTEN itself is also subjected to deliberated regulation to ensure its proper function. Defects in PTEN regulation have a profound impact on carcinogenesis. In this review, we briefly discuss recent advances concerning PTEN regulation and how such knowledge facilitates our understanding and further exploration of PTEN biology. The carboxyl-tail of PTEN, which appears to be associated with multiple types of posttranslational regulation, will be under detailed scrutiny. Further, a comparative analysis of PTEN and p53 suggests while p53 needs to be activated to suppress tumorigenesis (a dormant gatekeeper), PTEN is probably a constitutive surveillant against cancer development, thus a default gatekeeper.
Collapse
Affiliation(s)
- Xinjiang Wang
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | | |
Collapse
|
243
|
Chow JYC, Cabral JA, Chang J, Carethers JM. TGFbeta modulates PTEN expression independently of SMAD signaling for growth proliferation in colon cancer cells. Cancer Biol Ther 2008; 7:1694-9. [PMID: 18769113 DOI: 10.4161/cbt.7.10.6665] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Signaling pathways enabling transforming growth factor-beta (TGFbeta)'s conversion from a tumor suppressor to a tumor promoter are not well characterized. TGFbeta utilizes intracellular SMADs to mediate growth suppression; however, TGFbeta-induced proliferative pathways may become more apparent when SMAD signaling is abrogated. Here, we determined regulation of the tumor suppressor PTEN by TGFbeta utilizing SMAD4-null colon cancer cells. TGFbeta downregulated PTEN mRNA and simultaneously induced growth proliferation. TGFbeta also induced both SMAD2 and SMAD3 nuclear translocation, but only triggered SMAD2-specific transcriptional activity in the absence of SMAD4. Interference of SMAD2 with DN-SMAD2 enhanced TGFbeta-induced cell proliferation, but downregulation of PTEN expression by TGFbeta was unaffected. TGFbeta increased PI3K tyrosine phosphorylation, and inhibition of PI3K pharmacologically or by DN-p85 transfection reversed both TGFbeta-induced PTEN suppression and TGFbeta-induced cell proliferation. Thus, TGFbeta activates PI3K to downregulate PTEN for enhancement of cell proliferation that is independent of SMAD proteins.
Collapse
Affiliation(s)
- Jimmy Y C Chow
- Department of Medicine, University of California San Diego, La Jolla, CA 92093-0063, USA
| | | | | | | |
Collapse
|
244
|
Abstract
Class I phosphoinositide 3-kinase (PI3K) is a dimeric enzyme, consisting of a catalytic and a regulatory subunit. The catalytic subunit occurs in four isoforms designated as p110 alpha, p110 beta, p110 gamma and p110 delta. These isoforms combine with several regulatory subunits; for p110 alpha, beta and delta, the standard regulatory subunit is p85, for p110 gamma, it is p101. PI3Ks play important roles in human cancer. PIK3CA, the gene encoding p110 alpha, is mutated frequently in common cancers, including carcinoma of the breast, prostate, colon and endometrium. Eighty percent of these mutations are represented by one of the three amino-acid substitutions in the helical or kinase domains of the enzyme. The mutant p110 alpha shows a gain of function in enzymatic and signaling activity and is oncogenic in cell culture and in animal model systems. Structural and genetic data suggest that the mutations affect regulatory inter- and intramolecular interactions and support the conclusion that there are at least two molecular mechanisms for the gain of function in p110 alpha. One of these mechanisms operates largely independently of binding to p85, the other abolishes the requirement for an interaction with Ras. The non-alpha isoforms of p110 do not show cancer-specific mutations. However, they are often differentially expressed in cancer and, in contrast to p110 alpha, wild-type non-alpha isoforms of p110 are oncogenic when overexpressed in cell culture. The isoforms of p110 have become promising drug targets. Isoform-selective inhibitors have been identified. Inhibitors that target exclusively the cancer-specific mutants of p110 alpha constitute an important goal and challenge for current drug development.
Collapse
|
245
|
Abstract
The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor is a phosphatase that antagonizes the phosphoinositol-3-kinase/AKT signaling pathway and suppresses cell survival as well as cell proliferation. PTEN is the second most frequently mutated gene in human cancer after p53. Germline mutations of PTEN have been found in cancer susceptibility syndromes, such as Cowden syndrome, in which over 80% of patients have mutations of PTEN. Homozygous deletion of Pten causes embryonic lethality, suggesting that PTEN is essential for embryonic development. Mice heterozygous for Pten develop spontaneous tumors in a variety of organs comparable with the spectrum of its mutations in human cancer. The mechanisms of PTEN functions in tumor suppression are currently under intense investigation. Recent studies demonstrate that PTEN plays an essential role in the maintenance of chromosomal stability and that loss of PTEN leads to massive alterations of chromosomes. The tumor suppressor p53 is known as a guardian of the genome that mediates the cellular response to environmental stress, leading to cell cycle arrest or cell death. Through completely different mechanisms, PTEN also protects the genome from instability. Thus, we propose that PTEN is a new guardian of the genome. In this review, we will discuss new discoveries on the role of PTEN in tumor suppression and explore mechanisms by which PTEN maintains genomic stability.
Collapse
|
246
|
Li L, Dutra A, Pak E, Labrie JE, Gerstein RM, Pandolfi PP, Recht LD, Ross AH. EGFRvIII expression and PTEN loss synergistically induce chromosomal instability and glial tumors. Neuro Oncol 2008; 11:9-21. [PMID: 18812521 DOI: 10.1215/15228517-2008-081] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Glioblastomas often show activation of epidermal growth factor receptor (EGFR) and loss of PTEN (phosphatase and tensin homolog deleted on chromosome 10) tumor suppressor, but it is not known if these two genetic lesions act together to transform cells. To answer this question, we infected PTEN-/- neural precursor cells with a retrovirus encoding EGFRvIII, which is a constitutively activated receptor. EGFRvIII PTEN-/- cells formed highly mitotic tumors with nuclear pleomorphism, necrotic areas, and glioblastoma markers. The transformed cells showed increased cell proliferation, centrosome amplification, colony formation in soft agar, self-renewal, expression of the stem cell marker CD133, and resistance to oxidative stress and ionizing radiation. The RAS/mitogen-activated protein kinase (ERK) and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathways were activated, and checkpoint kinase 1 (Chk1), the DNA damage regulator, was phosphorylated at S280 by Akt, suppressing Chk1 phosphorylation at S345 in response to ionizing irradiation. The PTEN-/- cells showed low levels of DNA damage in the absence of irradiation, which was increased by EGFRvIII expression. Finally, secondary changes occurred during tumor growth in mice. Cells from these tumors showed decreased tumor latencies and additional chromosomal aberrations. Most of these tumor lines showed translocations of mouse chromosome 15. Intracranial injections of one of these lines led to invasive, glial fibrillary acidic protein-positive, nestin-positive tumors. These results provide a molecular basis for the occurrence of these two genetic lesions in brain tumors and point to a role in induction of genomic instability.
Collapse
Affiliation(s)
- Li Li
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | | | | | | | | | | | | | | |
Collapse
|
247
|
|
248
|
Abstract
The PTEN hamartoma tumor syndromes (PHTS) are a collection of rare clinical syndromes characterized by germline mutations of the tumor suppressor PTEN. These syndromes are driven by cellular overgrowth, leading to benign hamartomas in virtually any organ. Cowden syndrome (CS), the prototypic PHTS syndrome, is associated with increased susceptibility to breast, thyroid, and endometrial cancer. PTEN is located on chromosome 10q22-23 and negatively regulates the prosurvival PI3K/Akt/mTOR pathway through its lipid phosphatase activity. Loss of PTEN activates this pathway and leads to increased cellular growth, migration, proliferation, and survival. Clinical management of patients with PHTS, particularly those with CS, should include early and frequent screening, surveillance, and preventive care for associated malignancies. Concomitant with improved understanding of the biology of PTEN and the PI3K/Akt/mTOR pathway, inhibitors of this pathway are being developed as anticancer agents. These medications could have applications for patients with PHTS, for whom no medical options currently exist.
Collapse
Affiliation(s)
- Gideon M Blumenthal
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | | |
Collapse
|
249
|
|
250
|
Abstract
Since the histologic description of the hamartomatous polyp in 1957 by Horrilleno and colleagues, descriptions have appeared of several different syndromes with the propensity to develop these polyps in the upper and lower gastrointestinal tracts. These syndromes include juvenile polyposis, Peutz-Jeghers syndrome, hereditary mixed polyposis syndrome, and the phosphatase and tensin homolog gene (PTEN) hamartoma tumor syndromes (Cowden and Bannayan-Riley-Ruvalcaba syndromes), which are autosomal-dominantly inherited, and Cronkhite-Canada syndrome, which is acquired. This article reviews the clinical aspects, the molecular pathogenesis, the affected organ systems, the risks of cancer, and the management of these hamartomatous polyposis syndromes. Although the incidence of these syndromes is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in patients at risk.
Collapse
Affiliation(s)
- Daniel Calva
- Resident in Surgery, Roy J. and Lucille A. Carver University of Iowa College of Medicine, Iowa City, IA
| | - James R. Howe
- Professor of Surgery, Chief, Division of Surgical Oncology and Endocrine Surgery, Roy J. and Lucille A. Carver University of Iowa College of Medicine; Iowa City, IA
| |
Collapse
|