Jonas Nilsson jonas.a.nilsson@surgery.gu.se Sahlgrenska Cancer Center Bilder gjorda av Per Holmfeldt och Jonas Nilsson Benign tumor Basic tumor nomenclature Malignant tumor = cancer Metastasis Carcinoma: cancer derived from epithelial cells (90% of all cancers) Sarcoma: cancer derived from mesenchymal tissue Leukemia/lymphoma: cancer derived from hematopoietic cells
1. 2. Cancer development a multi-step affair Uncontrolled proliferation and escape from apoptosis Angiogenesis, formation of new blood vessels 3. Metastasis X X X X X X X X X X X X 1. 2. 3. Genomic stability, an obstacle for tumor progression Tumors never arise from a single mutational event; many are required to produce a full-blown cancer Due to the low normal mutation frequency (10-7 per gene per cell generation), cancer development is statistically improbable A tumor cell must therefore acquire a capability to accumulate genetic changes faster than a normal cell X Instability at the nucleotide level Microsatellite INstability (MIN) Instability at the chromosomal level Chromosomal INstability (CIN)
Example of changes in chromosome number Normal centrosome duplication Abnormal centrosome duplication Normal karyotype Abnormal karyotype Chromosomal instability through loss of APC APC can function as a MT end stabilizing protein ( ) and during mitosis facilitating stable MT-kinetochore connection Centromere Centrosome APC Kinetochore Loss of APC can lead to chromosomal instability
Example of changes in chromosome composition DNA strand break DNA duplication End fusion Chromosomal separation, new break Gene loss Telomere Undetected DNA break (requires defective p53 pathway) Gene amplification The six original hallmarks of cancer
Oncogenes and tumor suppressors An oncogene ( ) is a gene that when mutated or expressed at abnormally-high levels, contributes to converting a normal cell into a tumor cell Gene A Gene A X or Ras Bcl-2 A tumor suppressor ( ) is a gene in which loss or inactivation, through recessive loss-of-function mutations, contributes to converting a normal cell into a tumor cell Gene B Gene B or ZZZ Rb 1. Self-sufficiency in proliferative signals Mitogen signaling Cdk G1 DNA synthesome Production of DNA synthesomes Rb E2F Cdk Production of S cyclin P Cdc6 P ORC S Initiation of replication DNA synthesome
XGF Mitogen signaling pathways Wnt Hedgehog RTK Frizzled Patched Ras Dishevelled Smoothened Raf APC GSK-3!" Axin Fused Erk!-catenin" SuFu myc myc G1 Gli G1 myc G1 Why different mutations occur in different tumors Different cells use different signaling pathways for mitogen signaling, therefore usually only one signaling machinery is present and susceptible for mutations Cell type A Cell type B Cell type C Mitogen signaling: Mutation in: RTK signaling RTK Wnt Hedgehog Wnt signaling Hedgehog signaling
The retinoblastoma pathway 2. Insensitivity to anti-growth signals Mitogen signaling p15 p21 Cdk G1 p16 HPV E7 Rb E2F Cdk S DNA synthesome P Cdc6 P ORC TGF-! signaling pathway TGF-! TGF-! Type I receptor TGF-! P.M. P P Type II receptor Smad 2/3 P Smad 4 Smad 2/3 P Smad 4 p15 Smad 7 Target genes Negative feedback loop
3. Evading cell death (apoptosis) Survival factor signaling Ligand BH3 only Death receptor Bcl-2 Cytosolic Bax Cyt. C FADD Caspase 8 Caspase 9 Caspase 3 Apoptosis PI3-Kinase signaling pathway or PI-3 K G-protein coupled receptor RTK P P P 3 3 PTEN P P PKB/Akt G1 + Cell growth elf4e Bad Apoptosis
4. Limitless replicative potential Telomeres: stretches of repetitive DNA at the chromosome ends that can form a protective loop structure 5 3 Complementarity due to the repetitive sequence 5 3 -GGGTTAGGGTTAGGGTTA -CCCAATCC 5 3 G G G T AT CCCAAT T Chromosome lacking telomeres will trigger a p53 dependent cell cycle block A Telomerase, usually not expressed in somatic cells To maintain telomere length tumor cells can re-start expression of telomerase. An alternative mechanism employs enzymes that are involved in DNA recombination Make new blood vessel! 5. Sustained angiogenesis Blood vessel Diffusion of O 2 and nutrients < 100 µm Too long Endothelial cell Make new blood vessel!
Angiogenesis formation of new blood vessels 1. Arteria 3. 4. 2. Requirements for angiogenesis 1. Protease production Binding partners 2. 3. 4. Cell migration Cell proliferation Cell differentiation Vein Vascular Endothelial Growth Factor - VEGF 1. Constitutively produced in all tissues 2. Constitutively degraded in all tissues, unless Ras HIF-1 pvhl 4. Ras dependent signaling can increase expression levels of HIF-1 VEGF gene VEGF 3. hypoxia (low O 2 ) HIF-1 Ub Ub Ub Proteosome
Angiogenic factors affecting endothelial cells Activators Inhibitors VEGF Thrombospondin-1 p53 Loss of p53 loss of angiogenisis inhibition Tumor with active p53 Tumor without active p53 No angiogenesis Angiogenesis Regulation of angiogenesis Ras pvhl HIF-1 p53 Avastin! VEGF Thrombospondin-1 Angiogenesis
6. Metastasis capability Metastasis, the ability of cancer cells to migrate, results from multiple mutation events 1. Basal lamina 3. 2. 40-120 nm 4. 1. 2. 3. Loss of cell-cell adhesion Loss of cell-ecm adhesion, anchorage independent survival Proteolytic degradation of the ECM 4. Migration through the ECM Example of loss of cell-cell adhesion Loss of function of cadherins is an important step in generating daughter tumors (metastasis) Benign tumor Malignant tumor = cancer Tumor progression Loss of cadherin and therefore cell-cell interaction capability in one tumor cell Migration, resettlement and further proliferation Metastasis
Penetration of basal lamina Collagen IV fibril 1. 2. 3. Laminin 1. 2. 3. Loss of laminin receptor (integrin) Expression of collagenase Cytoskeletal changes Making it through the ECM Cell secretes proteases to clear a path through the ECM Blood or lymphatic vessel
Tumor cell entering the blood system Where will tumors metastasize? Blood flow pattern determine the metastasis pattern in most case (~70%) Capillary of the lung Lung metastasis Stomach or intestinal tumor cell entering the blood system Capillary of the liver Liver metastasis Where will tumors metastasize part II? Seed-soil pattern determine the metastasis pattern in other cases (~30%) Prostate tumor cell entering the blood system Adjacent bone cells produce specific factors needed for tumor cell growth Capillary of a bone No lung metastasis due to nonfavorable climate Capillary of the lung X X
p53 - a player in many pathways DNA damage ATM Arf Aberrant/incomplete proliferation signals Mdm2 p53 HPV E6 Cdk p21 G1,G1/S & S Insensitivity to anti-growth signals Bax PUMA Bcl-2 Evading cell death Thrombospondin-1 Sustained angiogenesis Tumor progression in the colon 2. 3. X X X X X X 5. 1. X X X X X X 4. 6. 1. 2. 3. Self-sufficiency in proliferative signals Insensitivity to Anti-growth signals Evading cell death 4. Limitless replicative potential Sustained angiogenesis 5. & 6. Metastasis capability
Tumor progression in colon carcinoma I Loss of APC Wnt APC APC!-catenin" G1 MMP7 Promotion of chromosomal instability Self-sufficiency in proliferative signals Metastasis capability Tumor progression in colon carcinoma II Loss of SMAD4 TGF -! Dominant mutation in RAS XGF Smad 4 Ras p15 G1 VEGF Make new blood vessel! Insensitivity to antigrowth signals Self-sufficiency in proliferative signals Sustained angiogenesis
Tumor progression in colon carcinoma III DNA damage Aberrant/incomplete proliferation signals Loss of p53 p53 p21 Bax PUMA Thrombospondin-1 Make new blood vessel! Insensitivity to anti-growth signals Evading cell death Sustained angiogenesis Tumor progression in colon carcinoma IV Expression of telomerase Loss of E-CADHERIN AT CCCAAT Limitless replicative potential Metastasis capability The End
Fulfilling the hallmarks of cancer in colon cancer 1. Self-sufficiency in proliferative signals APC Ras 2. Insensitivity to anti-growth signals Smad 4 p53 3. Evading cell death (apoptosis) p53 4. Limitless replicative potential AT CCCAAT Telomerase 5. Sustained angiogenesis Ras p53 6. Metastasis capability APC E cadherin The updated hallmarks of cancer
7. Evasion of immune surveillance Cytotoxic T cell MHC I Cytotoxic T cell FADD Fas/FasL NK cell MICA Perforin Granzyme ER Caspase 8 Caspase 3 Peptides Proteins Caspase 3 Apoptosis Apoptosis Cellular metabolism an overview Proteins Carbohydrates Fats (Triacylglycerol) Glycerol Glycolysis Pyruvate Fatty acid Fatty acid Fatty acid Acetyl CoA! oxidation Krebs cycle Electron transport chain and oxidative phosphorylation
ATP generation in the cytosol - glycolysis Glucose Glycolysis 2 X ATP 2 X NADH 2 X NAD + 2 X NAD + 2 X NADH 2 X Aerobic In mitochondrion (transition reaction) Pyruvate Anaerobic In cytosol (fermentation) 2 X NADH 2 X NAD + CO 2 2 X Acetyl CoA 2 X Lactate Glycolysis and the Warburg effect Glucose HK2 Warburg effect: Tumor cells use glycolysis instead of TCA/respiration even in the presence of oxygen! PGI PFK PPP Warburg hypothesis: Tumor cells do not have a functional respiration ALD GAPDH PGK PGM ENO Why? Glycolysis provide the cell with: Energy - ATP Building blocks (PPP) Fat Nucleotide Otto Warburg Nobel Prize 1931 PKM Pyruvate PDH Lactate Acetyl-CoA TCA Fat How? Oncogenes Myc Receptor tyrosine kinase Ras Tumor suppressors p53 LKB Hypoxia HIF-a
Targeting the hallmarks of cancer for therapy Recommended reading 1. Hanahan & Weinberg Hallmarks of Cancer Cell 2000, 100:57-70 2. Hanahan & Weinberg Hallmarks of Cancer: the next generation. Cell 2011, 144:546-574 3. Course book