Molecular Biology of Cancer Marek Svoboda Molecular Biology of Cancer • There is a broad consensus that cancer is, in essence, a genetic disease • The development of fully malignant cancers requires accumulation of molecular alterations in the genome of somatic cells  Multistep tumorigenesis Molecular Biology of Cancer • Multistep tumorigenesis  How many and what kind of genes are affected? – Human genome contains approximately 3x109 nucleotides (3 000 Mb) in 23 chromosomes  ~ 25 000 genes  ~ 180 000 exomes ( = ~ 1 % of genome = 30 Mb in coding regions) • The variation in mutational frequency between different tumors is extraordinary: – Cancer genomes have an average of 30 to 100 somatic alterations per tumor (= 1-3 per Mb in coding regions) Molecular Biology of Cancer • The variation in mutational frequency between different tumors is extraordinary: – the lowest mutation rates: pediatric and hematologic cancers (0,001 per Mb of DNA in coding regions), the highest mutation rates: melanoma, lung cancers (400 per Mb of DNA in coding regions) The prevalence of somatic mutations across human cancer types: Molecular Biology of Cancer • Although the specific mutations that cause human cancers vary greatly between types of cancers and individuals, the broad consequences of these mutations are abnormal phenotypes that are shared by most cancers  „Hallmarks of cancer“ – Sustaining proliferative signaling Soběstačnost v produkci růstových faktorů – Evading growth suppresors Necitlivost k supresorům růstu – Resisting cell death Poškození apoptózy – Enabling replicative immortality Neomezený replikační potenciál – Inducing angiogenesis Indukce angiogeneze – Activating invasion and metastasis Aktivace invaze a metastazování – Reprogramming energy metabolism Změna energetického metabolismu – Evading immune destruction Únik před imunitním systémem Molecular Biology of Cancer • Two ubiquitous characteristics facilitate the acquisition of hallmark capabilities – Genome instability and mutation Nestabilita genomu – Tumor-promoting inflammation Nádorem vyvolaný zánět Molecular Biology of Cancer Genome instability and mutation • DNA damage can occur in several different forms, including SSBs or DSBs • In higher eukaryotes, genomic stability is essential for healthy functioning and cell survival. DNA damage may induce mutations and can lead to cell death via apoptosis. Therefore, several repair mechanisms have evolved to maintain the integrity of the genome • BER is a key pathway in the repair of SSBs and is reliant on the enzyme poly(ADP-ribose) polymerase (PARP) • For DSB repair, two pathways predominate: 1.Homologous recombination (HR) that involves a protein kinase, ataxia-telangiectasia mutated (ATM) 2.Non-homologous end-joining (NHEJ) that requires DNA-dependent protein kinase (DNA-PK)2 HR is the most accurate mechanism for repairing DSBs, whereas NHEJ is rarely error-free2 Molecular Biology of Cancer Genome instability and mutation – The ability of genome maintenance systems to detect and resolve defects in the DNA ensures that rates of spontaneous mutation in normal cells of the body are typically very low. – The genomes of most cancer cells, by contrast, are full of these alterations, reflecting loss of genomic integrity with concomitantly increased rates of mutation. – This heightened mutability appears to accelerate the generation of variant cells, facilitating the selection of those cells whose advantageous phenotypes enable their clonal expansion. Molecular Biology of Cancer Molecular Biology of Cancer • Tumor promoting inflamation Molecular Biology of Cancer • Tumor promoting inflamationTumor promoting inflamation Molecular Biology of Cancer • Genome instability and mutation  Clonal evolution models • The clonal selection model • The parallel evolution model • The dynamic heterogeneity model • In the stem cell model Molecular Biology of Cancer • Although the specific mutations that cause human cancers vary greatly between types of cancers and individuals, the broad consequences of these mutations are abnormal phenotypes that are shared by most cancers  „Hallmarks of cancer“ – Sustaining proliferative signaling Soběstačnost v produkci růstových faktorů – Evading growth suppresors Necitlivost k supresorům růstu – Resisting cell death Poškození apoptózy – Enabling replicative immortality Neomezený replikační potenciál – Inducing angiogenesis Indukce angiogeneze – Activating invasion and metastasis Aktivace invaze a metastazování – Reprogramming energy metabolism Změna energetického metabolismu – Evading immune destruction Únik před imunitním systémem Molecular Biology of Cancer • „Hallmarks of cancer“ Molecular Biology of Cancer Sustaining proliferative signaling: - Somatic activation mutations in oncogenes (e.g. HER2,PI3K,RAS,RAF,MYC) - Disruption of negative-feedback mechanisms (e,g, PTEN, mTOR) Molecular Biology of Cancer Sustaining proliferative signaling: RAS and PI3K signaling pathways Molecular Biology of Cancer Evading growth suppresors : - Cell cycle control (e.g. Rb, TGF-b) - Cell Death control (e.g. p53) Molecular Biology of Cancer Resisting cell death: - Extrinsic apoptotic program (Death receptors: TNF, FASL, TRAIL  Casp8) - Intrinsic apoptotic program (Bcl-2/Bax, Cytochrom C, p53  Casp9) Molecular Biology of Cancer Resisting cell death: - Extrinsic apoptotic program (Death receptors: TNF, FASL, TRAIL  Casp8) - Intrinsic apoptotic program (Bcl-2/Bax, Cytochrom C, p53  Casp9) Apoptosis inhibition Cancer cell strategy Molecular Biology of Cancer Inducing angiogenesis: Molecular Biology of Cancer Activating invasion and metastasis: - Epithelial-to-Mesenchymal Transition - Loss of contact inhibition (E-cadherin/CDH1, integrins) - Activation of EMT program (Snail, Slug, Twist,…) - Stromal cell contribution (mesenchymal stem cells, macrophages) Molecular Biology of Cancer Activating invasion and metastasis: - Epithelial-to-Mesenchymal Transition - Loss of contact inhibition (E-cadherin/CDH1, integrins) - Activation of EMT program (Snail, Slug, Twist,…) - Stromal cell contribution (mesenchymal stem cells, macrophages) Molecular Biology of Cancer Reprogramming energy metabolism: - Glycolysis via oxydative phosphorylation  arebic glycolysis - The common feature of this altered metabolism is increased glucose uptake and fermentation of glucose to lactate. This phenomenon is observed even in the presence of completely functioning mitochondria and together is known as the Warburg Effect. - Upregulation of glucose transporter GLUT1 Molecular Biology of Cancer – Evading immune destruction Molecular Biology of Cancer – Evading immune destruction: • Defective antigen presentation • Tolerance and Adaptation • Immunosuppressive Cells Molecular Biology of Cancer – Evading immune destruction Molecular Biology of Cancer Evading immune destruction Molecular Biology of Cancer Evading immune destruction Molecular Biology of Cancer: TKI Molecular Biology of Cancer: TKI Molecular Biology of Cancer: Angiogenesis-I Molecular Biology of Cancer: Angiogenesis-I Molecular Biology of Cancer: others Colorectal cancer 90 % 60 - 80 % 40 - 73 % 14 % Kvalitnější a dostupnější diagnostika a léčba 1980  Adjuvantní léčba 1990  CT diagnostika  MRI 5 % 75 % 40–70 % 30–65 % Palliative care, including targeted treatment, has led to prolongation median survival from 5 to 30 months5leté přežití SEER Cancer Statistics 1975-2000, 2000 – 2013 Gustavsson et al., Clinical Colorectal Cancer 2015 (14),1:1-10 Ras-wt Overall survival of patients with metastatic colorectal carcinoma Targeted anti-HER2 therapy breast cancer 1. Line of palliative therapy (metastatic breast cancer) Smith et al. Anticancer Drugs 2001