Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Principles of Tumor Molecular Biology Ahmed Elkhodary Professor of Medical Oncology NCI Cairo, Egypt Consultant Medical Oncologist KCCC, Kuwait 2013 Cancer cells developed capacity for largely unregulated growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Characteristics of cancer cells: •Capabilities of self-sufficiency in growth signals • Insensitivity to antigrowth signals • Evasion of apoptosis •Limitless replicative potential •Sustained angiogenesis • Potentials for tissue invasion and metastasis Genomic instability was noted as a driving force for acquiring these malignant characteristics Control of Normal Cell Growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Signal Transduction Pathway General outline of signal transduction pathway 2 Control of Normal Cell Growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Cell Cycle •G1 : Proteins and RNA are synthesized for specialized cell functions The cellular contents excluding the chromosomes are duplicated •S phase (DNA synthesis): The cellular content of DNA doubles and each of the 46 chromosomes is duplicated •G2 phase: DNA synthesis ceases and protein and RNA synthesis continues The cell “double check” the duplicated chromosomes for any errors and making any needed repair • M phase (mitosis): The rates of protein and RNA synthesis diminish abruptly while the genetic material is segregated into daughter cells After completion of mitosis, the new cells enter either the G0 or G1 Cell cycle Cell cycle Control of Normal Cell Growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Regulation of Translation and Transcription The normal populations of cells are classified into two main groups: The immortal cells: ─Germ cells ─Stem cells ─Partially differentiated cells The fully mature specialized cells: Cannot reproduce further generations Transcription and Translation Control of Normal Cell Growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Pattern of Malignant Growth Growth Signaling Extracellular domine Growth signaling Gompertzian tumor growth curve 1 Intracellular domine 2 TUMOR GROWTH Sigmoid-shaped number of curve cancer cells 10 12 3 10 9 4 5 detectable cancer 2. Activation of receptor intracellular domine 3. Activation of intracellular signal cascades 4. Gene expression/cell cycle progression 5. Initiation of different cell functions time undetectable cancer limit of clinical detection 1. Stimulation of a receptor diagnostic threshold (1cm) host death •1x109 cells= one gram of tissue= mass of 1 cm diameter •Tumors with 1012 and 1013 cells (about 2 to 20 lb of cancer) usually result in damage to vital organs and death of the host • A 50% reduction in tumor mass represents only a one-third log decrease in tumor volume Control of Normal Cell Growth Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Antigrowth Signaling less is known about the role of antigrowth factors in the evasion of antiproliferative signals ─TGF-β ─Retinoblastoma protein (pRb) pathway Antigrowth signaling can be disabled or disrupted through: ─ Mutations in transmembrane receptors ─Intracellular signaling pathways are disrupted and become unresponsive to TGF-β signaling or other antigrowth stimulation Growth Inhibitors and Antigrowth Inducers • Cancer cells invariably harbor mutations in a number of critical genes encoding proteins involved in cell proliferation Each of these mutated proteins represents a potential target for new anticancer agents •Therapeutic strategies include targeting extracellular growth factors and their receptors, or intracellular transducers of growth or antigrowth signals Survival and Death Networks Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Apoptosis Pathways Intrinsic pathway – mitochondria mediated; caspase 9 Extrinsic pathway – involves death receptors (TNFreceptor, Fas); caspase 8 Converge to active executioner caspases 3 and 7 Caspase 9 Therapy: Apoptotic Inducers Caspases are potent proteases, cutting up proteins inside the cell and digesting the cell from within Caspases 3,7 Activation APOPTOSIS Caspases are potent proteases They cut up cell proteins and digest the cell from inside Limitless Replicative Potential Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Senescence : Normal somatic cell loses the ability to divide after certain number of cell divisions Differentiation : Cells develop into specialized cell types and permanently withdrawn from the cell cycle, usually after a finite number of cell divisions Normal cell multiplication depends on regulated proliferation, intact apoptosis, and both senescence & differentiation processes Tumor cells multiplication depends on deregulated cell proliferation and evasion of apoptosis with disrupted senescence and differentiation processes All these processes must be disrupted in order for cancer cells to acquire limitless replicative potential (i.e., immortality) Therapy: Senescent Inhibitors and Differentiation Inducers Tumor Neovascularization “Angiogenesis” Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Tumour characteristics and environment promote VEGF expression and angiogenic switch EGF Small Avascular Dormant tumor Angiogenic switch Hypoxia PDGF IGF-1 HIF IL-8 bFGF VEGF Expression Larger tumor Vascular Metastatic potential Binding and activation of VEGF receptor VEGF release Angiogenesis is involved throughout tumour formation, growth and metastasis Premalignant stage Malignant tumour Tumour growth Vascular invasion Dormant micrometastasis Overt metastasis (Avascular tumour) (Angiogenic switch) (Vascularised tumour) (Tumour cell intravasation) (Seeding in distant organs) (Secondary angiogenesis) COX-2 Nitric oxide Oncogenes Increased expression (MMP, tPA, uPA, uPAr, eNOS, etc.) P– P– –P –P Survival Proliferation Migration ANGIOGENESIS IGF; PDGF = platelet-derived growth factor Permeability Stages at which angiogenesis plays a role in tumour progression Targeting Signaling via VEGF& VEGFR & PDGFR Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Angiogenesis PDGF Interferon-alpha VEGF PDGF VEGF Bevacizumab VEGFR PDGF-R Pericyte/fibroblast vascular smooth muscle Vascular endothelial cell/ tumor cell P Angiogenesis P Ras Vascular permeability X Raf P P P Tyrosine kinase inhibitors Thalidomide P Cell survival, proliferation, migration X Raf P Endothelial stabilisation P Ras Vascular formation, maturation Metastasis Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Metastasis is a multistep process in which tumor cells invade nearby tissues and colonize other parts of the body A complex set of biological functions must be acquired for a primary tumor to progress to metastatic disease Classically, the basic steps of metastasis include local invasion, intravasation, and survival in the circulation, extravasation, and colonization Metastatic Latency and Colonization: Disseminated cancer cells that have invaded a new microenvironment might progress or remain dormant as micrometastases may be for years The process is maintained by an overall balance between growth-promoting and death signals The ability of dormant micrometastases to colonize into macrometastases requires additional mutations in the cancer cell population, adjacent stromal cells, or both Therapy: Antimetastatic Drugs Immune Evasion Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology The immune system consists of many specialized cells They protect the body from bacterial, parasitic, fungal, and viral infections The immune system is also thought to play a role in the detection and elimination of malignant cells Immune cells can identify cancer cells that express tumor-specific antigens (molecules unique to cancer cells) or tumor-associated antigens (molecules differentially expressed by cancer cells and normal) Immunosuppressive Networks and Cancer: Tumors can induce immunosuppression through a variety of mechanisms such as expression of immunosuppressive molecules and induction of apoptosis in lymphoid cells Immunotherapy Active immunotherapeutic agents in oncology include monoclonal antibodies, cancer vaccines, and growth factors Oncogenesis (Carcinogenesis) Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Carcinogenesis or oncogenesis is a process by which normal cells are transformed into cancer cells •Neoplastic transformation occurs as a direct consequence of alterations to the cell genome • Mutations in DNA disrupt the orderly cell division process • Only mutations in certain types of genes which play vital roles in cell division, apoptosis, and DNA repair will cause a cell to lose control of its cell proliferation Typically, a series of several mutations to these genes is required before a normal cell transforms into a cancer cell Carcinogenesis Carcinogenic Viruses Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Search for tumor viruses in the genetic material of tumor cells lead to the uncovering of cancer causing genes (oncogenes) •In 1910, Peyton Rous discovered that Rous Sarcoma Virus (RSV) caused cancer in chickens. The transforming function of RSV resides in a SINGLE gene called vSrc This gene is called an “oncogene” In mid 70s, Src was detected in normal cells and called cSrc which is a proto-oncogene and not a transforming gene. Proto-oncogene does not cause human cancer Carcinogenic Viruses Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Several different types of virus cause cancer to develop in animals and transform cells in tissue culture •Viral infection contributes to the development of a few human tumors • Cell gene mutations, host immune deficiency or stimulation, and other viral infections are required before cells actually become malignant •About 12% of human cancers can be attributed to a viral infection Carcinogenic Viruses Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology RNA Retroviruses: RNA retroviruses cause cancers in animals and malignant transformation of human and animal cells in culture Retroviruses and Human Cancer: •HTLV-I causes lymphoblastic leukemia in southern Japan and other countries. It is the only virus that has been clearly shown to cause a human cancer •HTLV-II may cause a small percentage of hairy cell leukemia and a variety of T-cell lymphoproliferative disorders •HTLV-III (HIV) is associated with high-grade B-lymphocyte malignancies in patients with acquired immunodeficiency syndrome (AIDS) Carcinogenic Viruses Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology DNA Viruses Viruses that are known to cause human cancer such as HPV (cervical cancer), Hepatitis B (liver cancer), and EBV (a type of lymphoma) are all DNA viruses They may become incorporated into the cell genome. These Oncogenic DNA viral genes code for proteins that affect growth-regulating substances in the cell DNA oncogenesis has different mechanisms. More than one mechanism may be required to induce malignant transformation: •Interference with cellular inhibitors of growth, resulting in uncontrolled cell replication •Activation of cellular DNA and RNA synthesis by viral protein products •Insertional mutagenesis. Viral DNA is inserted into the host genome and disrupts normal growth control • Gene translocation and rearrangement Proto-oncogenes and Oncogenes Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Proto-oncogenes are normal constituents of cellular genome •Proto-oncogenes are highly conserved through evolution • Many of the same proto-oncogenes are found in life forms as diverse as humans and yeast. They appear to be essential to life •Proto-oncogenes are involved in positive control of cell growth and division: 1-The growth factors/receptors involved in the control of cell multiplication 2-The non-receptor protein kinases which add phosphate groups to target proteins and are important in signal transduction pathways 3-The transcription factors which regulate gene expression • Each proto-oncogene makes protein products that are differentially expressed during the cell cycle or at specific stages of development of a particular tissue RNA from transforming retroviruses is homologous with various proto-oncogenes Tumor Suppressor Genes Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology They are first discovered in 1960s by Henry Harris Tumor suppressor genes code for anti-proliferation signals and proteins that suppress mitosis, proliferation and cell growth They can temporarily halt cell division to carry out DNA repair Many tumor suppressor genes effect apoptosis signal transduction pathways Tumor suppressor genes are often disabled by cancer-promoting genetic changes Mutator (“Caretaker”) Genes Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology It is also known as micro-satellite instability genes or DNA repair genes Mutator gene products are involved in DNA replication and repair DNA Repair Genes or Mutator Genes Normal Function: To correct Normal Function: To correct errorserrors Normal DNA repair T C GA C Base pair mismatch No cancer TC T AC AG C T G TC TAC TCT AC AG C T G Cancer AG T G AG A T G No DNA repair Cancer and Mutated Genes Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Oncogenes are Mutant Forms of Proto-Oncogenes Three classes of genes frequently mutated in cancer: ─Proto-oncogenes and oncogenes ─Tumor suppressor genes Inactive growth factor receptor Inactive intracellular signaling protein Signaling molecule from active oncogene Activated gene regulatory protein ─Mutator genes Transcription Altered/excess growth-control proteins Cancer Cell can bypass normal growth control and Cell proliferation driven by divide uncontrollably internal oncogene signaling Proto-oncogenes and Oncogenes Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Role in Cancer •Mutated proto-oncogenes become oncogenes, modify their expression and function with subsequent increase in the amount or activity of the product protein •The oncogenes produce proteins that have the capacity to stimulate growth and proliferation out of control and leads to neoplastic transformation Oncogenes Normal cell •In cancer, oncogenes may be normal but expressed at high levels, or altered genes which have novel properties Normal genes regulate cell growth •Oncogenes are consistently associated with malignancy and may be of either cellular or retroviral origin •In general, more than one oncogene is abnormally active in cancer •Over 100 different oncogenes have been identified Cancer cell Oncogenes accelerate cell growth and division Mutated/damaged oncogene : Cancer cell can bypass normal growth control and divide uncontrollably Conversion of Proto-oncogenes to Oncogene Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Genes 1-Mutations result from changes in the nucleotide sequence of genomic DNA • large-scale mutations: Deletion or gain of a portion of a chromosome • Small-scale mutations : ─Point mutations ─ Deletions ─ Insertions in the promoter of a gene and affect its expression or may occur in the gene's coding sequence and alter the function or stability of its protein product 2-Disruption of a single gene results from integration of genomic material from a DNA virus or retrovirus 3-Genomic amplification Chromosomes 1-Aneuploidy: The presence of an abnormal number of chromosomes 2-Translocation Conversion of Proto-oncogenes to Oncogene Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Src/Ras Myc Her2/Neu & Myc Figure 20-33 Molecular Biology of the Cell (© Garland Science 2008) Myc Bcr/Abl Causes of Overproduction of Cancer Cells Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology For initiation, growth, and dissemination of cancer, multiple genes mutation is required Cancer Tends to Involve Multiple Mutations Benign tumor cells grow only locally and cannot spread by invasion or metastasis •Genetic abnormalities Malignant cells invade neighboring tissues, enter blood vessels, and metastasize to different sites •Failure of abnormal cells to undergo apoptosis •Tumor angiogenesis Time Mutation Cells inactivates proliferate suppressor gene Mutations Proto-oncogenes inactivate mutate to DNA repair oncogenes genes More mutations, more genetic instability, metastatic disease Biological Properties of Cancer Cells Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Acquisition of self-sufficiency in growth signals leading to unchecked growth •Loss of sensitivity to anti-growth signals leading to unchecked growth •Loss of capacity for apoptosis which allow growth despite genetic errors and external anti-growth signals •Loss of capacity for senescence leading to limitless replicative potential (immortality) •Acquisition of sustained angiogenesis allowing the tumor to grow beyond the limitations of passive nutrient diffusion •Acquisition of ability to invade neighboring tissues •Acquisition of ability to build metastases at distant sites; the classical property of malignant tumors Characteristics of Cancer Cells Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology •Clonal origin: Most cancer cells appear to originate from a single abnormal cell •Immortality: Cancer cells can proliferate indefinitely •Genetic instability •Loss of contact inhibition •Progressive independence of proliferation from growth factors and nutrients •Metastasis The Hallmarks of Cancer Different molecules involved in cancer pathogenesis Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Recent progress during the last 20 years may explain, not only the molecular paradigms for development of cancer phenotypes, but also finally being brought to force as new cancer therapeutics Molecular targeted agents have already made dramatic differences in the treatment of cancers that were previously considered untreatable Potential Therapeutic Targets MalignantTumors: Example of Therapeutic Targets Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Everolimus Bevacizumab Ligand mTOR Stimulation Inhibition Temsirolimus Trastuzumab VEGF PDGF TGF-α VEGFR PDGFR EGFR Raf Raf PTK787 Sorafenib Sorafenib Sunitinib AG-013736 (Axitinib) Cetuximab Panitumumab Erlotinib Gefitinib ZD6474 (Zactema) Sorafenib Other targets: Apoptosis(Velcade), Fusion proteins(Imatinib, Crizotinib) … Lapatinib Targeted Therapy of Cancer Many targets Therapeutic Decision Making in Advanced NSCLC: A 2012 Perspective clinicaloptions.com/oncology Sos-1 PI3-K Grb2 Ras Shc MEK Raf BUT: Where's the proper target? MEKK-1 JNK MKK-7 ERK AKT Courtesy of I. Serebriiskii and E. Golemis, Fox Chase Cancer Center.