Sanja Mijatović

Dysregulated signaling through the Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways is often the result of genetic alterations in critical components in these pathways or upstream activators. Unrestricted cellular proliferation and decreased sensitivity to apoptotic-inducing agents are typically associated with activation of these pro-survival pathways. This review discusses the functions these pathways have in normal and neoplastic tissue growth and how they contribute to resistance to apoptotic stimuli. Crosstalk and commonly identified mutations that occur within these pathways that contribute to abnormal activation and cancer growth will also be addressed. Finally the recently described roles of these pathways in cancer stem cells, cellular senescence and aging will be evaluated. Controlling the expression of these pathways could ameliorate human health.

William H. Chappell 1 , Linda S. Steelman 1,2 , Jacquelyn M. Long 2 , Ruth C. Kempf 2 , Stephen L. Abrams 1 , Richard A. Franklin 1 , Jörg Bäsecke 3 , Franca Stivala 4 , Marco Donia 4 , Paolo Fagone 4 , Graziella Malaponte 4 , Maria C. Mazzarino 4 , Ferdinando Nicoletti 4 , Massimo Libra 4 , Danijela Maksimovic-Ivanic 5 , Sanja Mijatovic 5 , Giuseppe Montalto 6 , Melchiorre Cervello 7 , Piotr Laidler 8 , Michele Milella 9 , Agostino Tafuri 10 , Antonio Bonati 11 , Camilla Evangelisti 12 , Lucio Cocco 12 , Alberto M. Martelli 12,13 , and James A. McCubrey 1 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University 2 Department of Physics, Greenville, NC 27858 USA 3 Department of Medicine University of Göttingen, Göttingen, Germany 4 Department of Biomedical Sciences, University of Catania, Catania, Italy 5 Department of Immunology, Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia 6 Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 7 Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy 8 Department of Medical Biochemistry Jagiellonian University Medical College, Krakow, Poland 9 Regina Elena Cancer Center, Via Elio Chianesi n.53, Rome 00144, Italy 10 University of Rome, La Sapienza, Department of Hematology-Oncology, Via Benevento 6, Rome 99161, Italy 11 University Hospital of Parma, Unit of Hematology and Bone-Marrow Transplantation, Via Gramsi n.14, Parma 43100, Italy 12 Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell’Apparato Locomotore, Università di Bologna, Bologna, Italy 13 IGM-CNR, Sezione di Bologna, C/o IOR, Bologna, Italy Keywords: Targeted Therapy, Combination Therapy, Drug Resistance, Cancer Stem Cells, Aging, Senescence, Raf, Akt, PI3K, mTOR Received: February 25, 2011; Accepted: March 10, 2011; Published: March 11, 2011; Correspondence: James A. McCubrey, e-mail: // // Abstract The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Integral components of these pathways, Ras, B-Raf, PI3K, and PTEN are also activated/inactivated by mutations. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of these pathways can contribute to chemotherapeutic drug resistance, proliferation of cancer initiating cells (CICs) and premature aging. This review will evaluate more recently described potential uses of MEK, PI3K, Akt and mTOR inhibitors in the proliferation of malignant cells, suppression of CICs, cellular senescence and prevention of aging. Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt/mTOR pathways play key roles in the regulation of normal and malignant cell growth. Inhibitors targeting these pathways have many potential uses from suppression of cancer, proliferative diseases as well as aging.

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Targeting these pathways is often complex and can result in pathway activation depending on the presence of upstream mutations (e.g., Raf inhibitors induce Raf activation in cells with wild type (WT) RAF in the presence of mutant, activated RAS) and rapamycin can induce Akt activation. Targeting with inhibitors directed at two constituents of the same pathway or two different signaling pathways may be a more effective approach. This review will first evaluate potential uses of Raf, MEK, PI3K, Akt and mTOR inhibitors that have been investigated in pre-clinical and clinical investigations and then discuss how cancers can become insensitive to various inhibitors and potential strategies to overcome this resistance.

// James A. McCubrey 1 , Linda S. Steelman 1 , William H. Chappell 1 , Stephen L. Abrams 1 , Giuseppe Montalto 2 , Melchiorre Cervello 3 , Ferdinando Nicoletti 4 , Paolo Fagone 4 , Grazia Malaponte 4 , Maria C. Mazzarino 4 , Saverio Candido 4 , Massimo Libra 4 , Jörg Bäsecke 5 , Sanja Mijatovic 6 , Danijela Maksimovic-Ivanic 6 Michele Milella 7 , Agostino Tafuri 8 , Lucio Cocco 9 , Camilla Evangelisti 10 , Francesca Chiarini 10 , Alberto M. Martelli 9,10 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA 2 Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 3 Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy 4 Department of Biomedical Sciences, University of Catania, Catania, Italy 5 Department of Medicine, University of Göttingen, Göttingen, Germany 6 Department of Immunology, Instititue for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia 7 Regina Elena National Cancer Institute, Rome, Italy 8 Sapienza, University of Rome, Department of Cellular Biotechnology and Hematology, Rome, Italy 9 Department of Biomedical and Neuromotor Sciences, Università di Bologna, Bologna, Italy 10 Institute of Molecular Genetics, National Research Council-Rizzoli Orthopedic Institute, Bologna, Italy Correspondence: James A. McCubrey , email: // Keywords : Targeted Therapy, Therapy Resistance, Mutations, Raf, Akt, PI3K, mTOR Received : August 12, 2012, Accepted : September 17, 2012, Published : September 20, 2012 Abstract The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cascades can contribute to: resistance to other pathway inhibitors, chemotherapeutic drug resistance, premature aging as well as other diseases. This review will first describe these pathways and discuss how genetic mutations and epigenetic alterations can result in resistance to various inhibitors.

// Nicole M. Davis 1 , Melissa Sokolosky 1 , Kristin Stadelman 1 , Stephen L. Abrams 1 , Massimo Libra 2 , Saverio Candido 2 , Ferdinando Nicoletti 2 , Jerry Polesel 3 , Roberta Maestro 4 , Antonino D’Assoro 5 , Lyudmyla Drobot 6 , Dariusz Rakus 7 , Agnieszka Gizak 7 , Piotr Laidler 8 , Joanna Dulińska-Litewka 8 , Joerg Basecke 9 , Sanja Mijatovic 10 , Danijela Maksimovic-Ivanic 10 , Giuseppe Montalto 11,12 , Melchiorre Cervello 12 , Timothy L. Fitzgerald 13 , Zoya N. Demidenko 14 , Alberto M. Martelli 15 , Lucio Cocco 15 , Linda S. Steelman 1 and James A. McCubrey 1 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University Greenville, NC 27858 USA 2 Department of Bio-Medical Sciences, University of Catania, Catania, Italy 3 Unit of Epidemiology and Biostatistics, Centro di Riferimento Oncologico, IRCCS, Aviano, Italy 4 Experimental Oncology 1, CRO IRCCS, National Cancer Institute, Aviano, Pordenone, Italy 5 Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA 6 Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine 7 Department of Animal Molecular Physiology, Institute of Experimental Biology, Wroclaw University, Wroclaw, Poland 8 Chair of Medical Biochemistry, Jagiellonian University Medical College, Kraków, Poland 9 Department of Medicine University of Göttingen, Göttingen, Germany 10 Department of Immunology, Institute for Biological Research “Sinisa Stankovic” University of Belgrade, Belgrade, Serbia 11 Biomedical Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 12 Consiglio Nazionale delle Ricerche,Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy 13 Department of Surgery, Brody School of Medicine at East Carolina University, Greenville, NC 14 Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY, USA 15 Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy Correspondence: James A. McCubrey, email: // Keywords : Targeted Therapy, Therapy Resistance, Mutations, PI3K, mTOR, rapamycin Received : June 04, 2014 Accepted : July 11, 2014 Published : July 12, 2014 Abstract The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2 , ER alpha, BRCA1, BRCA2, EGFR1 , PIK3CA , PTEN , TP53 , RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway ( e.g. , PIK3CA ) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway.