Buněčná signalizace – signální molekuly, membránové a nitrobuněčné receptory, signální dráhy Josef Srovnal Laboratoř experimentální medicíny DK LF UP a.

Prezentace na téma: "Buněčná signalizace – signální molekuly, membránové a nitrobuněčné receptory, signální dráhy Josef Srovnal Laboratoř experimentální medicíny DK LF UP a."— Transkript prezentace:

1 Buněčná signalizace – signální molekuly, membránové a nitrobuněčné receptory, signální dráhy
Josef Srovnal Laboratoř experimentální medicíny DK LF UP a FN Olomouc

2 Cíle semináře 1. Seznámit posluchače se způsoby buněčné signalizace
2. Poukázat na její vliv na vznik lidských onemocnění. 3. Upozornit na možnosti cílené léčby.

3 Proč signalizace? Komunikace – řízení – přežití – množení
– předání DNA

4 General Principles of Cell Signaling
Tok informace: signalizující buňka  signální molekuly  terčová (cílová) buňka

5 Signalizace - endokrinní
Signální molekuly – receptory – intracelulární - extracelulární – iontové kanály - Enzym. receptory - G protein receptory - proteinkinaza A - fosfolipaza C Signalizace - endokrinní - parakrinní - nervové - dotykové

6 Mezibuněčná signalizace volné signální molekuly vs
Mezibuněčná signalizace volné signální molekuly vs. membránové receptory

7 Signaling molecules Intra- and extracellular
Extracellular signaling molecules bind to either cell-surface receptors or intracellular receptors. Most signaling molecules are hydrophilic – - unable to cross the plasma membrane – - bind to cellsurface receptors - generate signals inside the target cell. Small signaling molecules diffuse across the plasma membrane and bind to receptors inside the target celleither in the cytosol or in the nucleus. Many of these small signaling molecules are hydrophobic and nearly insoluble in aqueous solutions - transported bound to carrier proteins - dissociate before entering the target cell.

8 Signaling mediated by secreted molecules
Many of the same types of signaling molecules are used in paracrine, synaptic, and endocrine signaling. The crucial differences lie in the speed and selectivity with which the signals are delivered to their targets.

9 The contrast between endocrine and synaptic signaling.
Endocrine cells and nerve cells work together to coordinate the diverse activities of the billions of cells in a higher animal. Endocrine cells secrete many different hormones into the blood to signal specific target cells. The target cells have receptors for binding specific hormones and thereby "pull" the appropriate hormones from the extracellular fluid. In synaptic signaling the specificity arises from the contacts between nerve processes and the specific target cells they signal: usually only a target cell that is in synaptic contact with a nerve cell is exposed to the neurotransmitter released from the nerve terminal. Whereas different endocrine cells must use different hormones in order to communicate specifically with their target cells, many nerve cells can use the same neurotransmitter and still communicate in a specific manner.

10 The same signaling molecule can induce different responses in different target cells
In some cases this is because the signaling molecule binds to different receptor proteins, as illustrated in (A) and (B). In other cases the signaling molecule binds to identical receptor proteins that activate different response pathways in different cells, as illustrated in (B) and (C). In all of the cases shown the signaling molecule is acetylcholine (D).

11 Signaling molecules binding to intracellular receptors
Note that all of them are small and hydrophobic. The active, hydroxylated form of vitamin D3is shown.

12 Intracellular receptor superfamily
A model of an intracellular receptor protein. In its inactive state the receptor is bound to an inhibitory protein complex that contains a heat-shock protein called Hsp90. The binding of ligand to the receptor causes the inhibitory complex to dissociate, thereby activating the receptor by exposing its DNA-binding site. The model shown is based on the receptor for cortisol, but all of the receptors in this superfamily have a related structure.

13 Early primary response and delayed secondary response - intracellular receptor protein activation
The response to a steroid hormone is illustrated, but the same principles apply for all ligands that activate this family of receptor proteins. Some of the primary-response proteins turn on secondary-response genes, whereas others turn off the primary-response genes.

14 Three classes of cell-surface receptors

15 Two major intracellular signaling mechanisms share common features
In both cases a signaling protein is activated by the addition of a phosphate group and inactivated by the removal of the phosphate. In (A) the phosphate is added covalently to the signaling protein by a protein kinase; in (B) a signaling protein is induced to exchange its bound GDP for GTP. To emphasize the similarity in the two mechanisms, ATP is shown as APP , ADP as APP, GTP as GPP , and GDP as GPP.

16 Signaling via G-Protein-linked Cell-Surface Receptors

17 A schematic drawing of a G-protein-linked receptor
Receptors that bind protein ligands have a large extracellular ligand-binding domain formed by the part of the polypeptide chain. Receptors for small ligands such as adrenaline have small extracellular domains, and the ligand-binding site is usually deep within the plane of the membrane. The parts of the intracellular domains that are mainly responsible for binding to trimeric G proteins are shown in orange,while those that become phosphorylated during receptor desensitization are shown in red.

18 Two major pathways by which G-protein-linked cell-surface receptors generate small intracellular mediators In both cases the binding of an extracellular ligand alters the conformation of the cytoplasmic domain of the receptor, causing it to bind to a G protein that activates (or inactivates) a plasma membrane enzyme. In the cyclic AMP (cAMP) pathway the enzyme directly produces cyclic AMP. In the Ca2+ pathway the enzyme produces a soluble mediator (inositol trisphosphate) that releases Ca2+ from the endoplasmic reticulum. Like other small intracellular mediators, both cyclic AMP and Ca2+ relay the signal by acting as allosteric effectors: they bind to specific proteins in the cell, altering their conformation and thereby their activity.

19 Cyclic AMP The synthesis and degradation of cyclic AMP (cAMP).
It is shown as a formula, a ball-and-stick model, and as a space-filling model.

20 A current model of how Gs couples receptor activation to adenylyl cyclase activation
As long as the extracellular signaling ligand remains bound, the receptor protein can continue to activate molecules of Gs protein, thereby amplifying the response. More important, an as can remain active and continue to stimulate a cyclase molecule for many seconds after the signaling ligand dissociates from the receptor, providing even greater amplification.

21 The activation of cyclic-AMP-dependent protein kinase (A-kinase)
The binding of cyclic AMP to the regulatory subunits induces a conformational change, causing these subunits to dissociate from the complex, thereby activating the catalytic subunits. Each regulatory subunit has two cyclic-AMP-binding sites, and the release of the catalytic subunits requires the binding of more than two cyclic AMP molecules to the tetramer. This greatly sharpens the response of the kinase to changes in cyclic AMP concentration. There are at least two types of A-kinase in most mammalian cells: type I is mainly in the cytosol, whereas type II is bound via its regulatory subunit to the plasma membrane, nuclear membrane, and microtubules. In both cases, however, once the catalytic subunits are freed and active, they can migrate into the nucleus (where they can phosphorylate gene regulatory proteins), while the regulatory subunits remain in the cytoplasm.

22 The stimulation of glycogen breakdown by cyclic AMP in skeletal muscle cells.
The binding of cyclic AMP to A-kinase activates this enzyme to phosphorylate and thereby activate phosphorylase kinase, which in turn phosphorylates and activates glycogen phosphorylase, the enzyme that breaks down glycogen.

23 The role of protein phosphatase-I in the regulation of glycogen metabolism by cyclic AMP
Cyclic AMP inhibits protein phosphatase-I, which would otherwise oppose the phosphorylation reactions stimulated by cyclic AMP. It does so by activating A-kinase to phosphorylate a phosphatase inhibitor protein, which then binds to and inhibits protein phosphatase-I.

24 Some Hormone-induced Cellular Responses Mediated by Cyclic AMP
Target Tissue Hormone Major Response Thyroid gland thyroid-stimulating hormone (TSH) thyroid hormone synthesis and secretion Adrenal cortex adrenocorticotropic hormone (ACTH) cortisol secretion Ovary luteinizing hormone (LH) progesterone secretion Muscle adrenaline glycogen breakdown Bone parathormone bone resorption Heart adrenaline increase in heart rate and force of contraction Liver glucagon glycogen breakdown Kidney vasopressin water resorption Fat adrenaline, ACTH, glucagon, TSH triglyceride breakdown Part III. Internal Organization of the Cell Chapter 15. Cell Signaling Signaling via G-Protein-linked Cell-Surface Receptors 11 Figure Adenylyl cyclase. In vertebrates the enzyme usually contains about 1100 amino acid residues and is thought to have two clusters of six transmembrane segments separating two similar cytoplasmic catalytic domains. There are at least six types of this form of adenylyl cyclase in mammals (types I-VI). All of them are stimulated by Gs, but type I, which is found mainly in the brain, is also stimulated by complexes of Ca2+ bound to the Ca2+-binding protein calmodulin (discussed later). Figure Adrenaline. This hormone (also called epinephrine) is made from tyrosine and is secreted by the adrenal gland when a mammal is stressed. Some Hormone-induced Cellular Responses Mediated by Cyclic AMP Target Tissue Hormone Major Response Thyroid gland thyroid-stimulating h. (TSH) thyroid h synthesis and secretion Adrenal cortex adrenocorticotropic h. (ACTH) cortisol secretion Ovary luteinizing h. (LH) progesterone secretion Muscle adrenaline glycogen breakdown Bone parathormone bone resorption Heart adrenaline heart rate and force Liver glucagon glycogen breakdown Kidney vasopressin water resorption Fat adrenaline, ACTH, glucagon, TSH triglyceride breakdown

25 Inositol phospholipid pathway
The activated receptor binds to a specific trimeric G protein (Gq), causing the a subunit to dissociate and activate phospholipase C-b, which cleaves PIP2 to generate IP3 and diacylglycerol. The diacylglycerol activates C-kinase. Both phospholipase C-b and C-kinase are water-soluble enzymes that translocate from the cytosol to the inner face of the plasma membrane in the process of being activated.

26 Inositol phospholipids (phosphoinositides)
The polyphosphoinositides (PIP and PIP2) are produced by the phosphorylation of phosphatidylinositol (PI). Although all three inositol phospholipids may be broken down in the signaling response, it is the breakdown of PIP2 that is most critical, even though it is the least abundant, constituting less than 10% of the total inositol lipids and less than 1% of the total phospholipids.

27 The hydrolysis of PIP2. Two intracellular mediators are produced when PIP2 is hydrolyzed: inositoltrisphosphate (IP3), which diffuses through the cytosol and releases Ca2+ from the ER, and diacylglycerol, which remains in the membrane and helps activate the enzyme proteinkinase C. There are at least three classes of phospholipase C - b, g, and delta - and it is the b class that is activated by G-protein-linked receptors.

28 Two intracellular pathways by which activated C-kinase can activate the transcription of specific genes In one ( red arrows) C-kinase activates a phosphorylation cascade that leads to the phosphorylation of a pivotal protein kinase called MAP-kinase, which in turn phosphorylates and activates the gene regulatory protein Elk-1. Elk-1 is bound to a short DNA sequence (called serum response element, SRE) in association with another DNA-binding protein (called serum response factor, SRF) . In the other pathway ( green arrows) C-kinase activation leads to the phosphorylation of Ik-B, which releases the gene regulatory protein NF-kB so that it can migrate into the nucleus and activate the transcription of specific genes.

29 Some Cellular Responses Mediated by G-Protein-linked Receptors Coupled to the Inositol-Phospholipid Signaling Pathway Target Tissue Signaling Molecule Major Response Liver vasopressin glycogen breakdown Pancreas acetylcholine amylase secretion Smooth muscle acetylcholine contraction Mast cells antigen histamine secretion Blood platelets thrombin aggregation

30 Signaling via Enzyme-linked Cell-Surface Receptors

31 Six subfamilies of receptor tyrosine kinases
Only one or two members of each subfamily are indicated. Note that the tyrosine kinase domain is interrupted by a "kinase insert region" in some of the subfamilies. The functional significance of the cysteine-rich and immunoglobulinlike domains is unknown.

32 The serine/threonine phosphorylation cascade activated by Ras and C-kinase
In the pathway activated by receptor tyrosine kinases via Ras, the MAP-kinase-kinase-kinase is often a serine/threonine kinase called Raf, which is thought to be activated by the binding of activated Ras. In the pathway activated by G-protein-linked receptors via C-kinase, the MAPkinase-kinase-kinase can either be Raf or a different serine/threonine kinase. Receptor tyrosine kinases may also activate a more direct signaling pathway to the nucleus by directly phosphorylating, and thereby activating, gene regulatory proteins that contain SH2domains.

33 Growth Factors and Tumor Growth and Metastasis
Mutations in HER family VEGF MMPs ras p53 COX-2 Tumor effects metastasis proliferation loss of apoptosis infinite replication angiogenesis invasion Cancer arises from the cumulative effects of multiple mutations in genes critical for cellular growth control, leading to aberrant cell growth. These mutations can result in: increased activity of oncogenes decreased activity of tumor suppressor genes dysregulation of growth factors or their receptors, such as the HER family and its ligands, leading to abnormal signal transduction dysregulation of cell-cycle regulatory proteins, such as p53. These deleterious mutations accumulate in the cell, overwhelming the usual controls, and allowing the tumor to evade the body’s defenses. Such mutations result in various abnormal properties, including the ability to divide indefinitely (cell immortality), insensitivity to apoptotic signals (absence of programmed cell death), stimulation of angiogenesis (establishing a tumor-supporting vascular network), and the capacity to invade other tissues (metastasis). These processes combine to drive uncontrolled cellular proliferation, and tumor growth and spread. Hanahan D, Weinberg RA. Cell. 2000;100:57-70. Primary tumor Hanahan D, Weinberg RA. Cell. 2000;100:57-70.

34 Biologic Control of Tumor Growth
Normal cells Receptors Autocrine factors Paracrine factors At a cellular level, tumor development, growth, and progression are determined by a complex interplay of factors. These include the activation and stimulation of tumor cell-surface receptors by autocrine factors released from the tumor cells (the so-called autocrine feedback loop) as well as by circulating paracrine factors released from stromal epithelial cells elsewhere in the body, in response to tumor-secreted paracrine factors. So, tumor cells drive their own uncontrolled growth, both directly and indirectly, via chemical messengers that trigger receptor-initiated cell signaling. Growth factors (or ligands) that bind to cell-surface receptors are important regulators of cell growth and division. Dysregulation of growth factors and/or their receptors provides a stimulus for the uncontrolled cell growth that is a primary characteristic of cancer. Examples of important growth factors are: epidermal growth factor (EGF) transforming growth factor alpha (TGF-a) heregulin insulin-like growth factor. Host stromal epithelium Tumor cell

35 The HER Family of Receptors
EGF TGF-a Amphiregulin Betacellulin HB-EGF Epiregulin Ligands: NRG2 NRG3 Heregulins Betacellulin Heregulins Cysteine- rich domains The HER family comprises four closely related transmembrane receptors: HER1/EGFR (erbB1), HER2 (erbB2 or neu), HER3 (erbB3), and HER4 (erbB4), of which HER1/EGFR and HER2 are the most studied. Each HER family receptor has a similar morphology, with an external (extracellular) ligand-binding domain, an anchoring (transmembrane) region, and an internal (cytoplasmic) domain with tyrosine-kinase (TK) activity (except for HER3 which lacks intrinsic TK). HER1/EGFR and HER2 are involved in the growth and differentiation of normal cells (although no ligand has been identified for HER2 yet), and importantly, they are dysregulated in many human cancers, suggesting a pivotal role in tumorigenesis.1,2 As a result, these receptors are a focal point for the development of novel targeted anticancer therapies. 1. Salomon D, Brandt R, Ciardiello F, et al. Crit Rev Oncol Hematol ;19: 2. Woodburn J. Pharmacol Ther. 1999;82: HER2 erbB2 neu HER1/EGFR erbB1 HER3 erbB3 HER4 erbB4 Tyrosine- kinase domains Salomon D, Brandt R, Ciardiello F, et al. Crit Rev Oncol Hematol. 1995;19: Woodburn J. Pharmacol Ther. 1999;82:

36 HER1/EGFR Dimerization
HER1 homodimer HER1-HER1 Three HER1-containing heterodimers HER1-HER2 HER1-HER3 HER1-HER4 Like all members of the HER family, individual HER1/EGFRs exist as monomers when inactive. Ligand binding causes either homodimerization (between monomers of the same receptor, for example HER1-HER1), or heterodimerization between the bound receptor and another member of the HER family (for example, HER1- HER2). Dimerization activates receptor TK via phosphorylation, triggering downstream signaling. HER2 is the most common heterodimerization partner for the HER family,1,2 possibly because, having no known ligand, it requires heterodimerization to activate its TK. HER3 has no intrinsic TK activity and must associate with another HER-family receptor to trigger signaling. 1. Pinkas-Kramarski R, Soussan L, Waterman H, et al. EMBO J. 1996;15: 2. Klapper LN, Glathe S, Vaisman N, et al. Proc Natl Acad Sci USA. 1999;96: Pinkas-Kramarski R, Soussan L, Waterman H, et al. EMBO J. 1996;15: Klapper LN, Glathe S, Vaisman N, et al. Proc Natl Acad Sci USA. 1999;96:

37 Effects of HER1/EGFR Activation
Extracellular Intracellular Transactivation P P Src PLCg GAP Grb2 Shc Nck Vav Grb7 Crk PKC Ras After HER1/EGFR ligand binding, dimerization, and TK phosphorylation, a complex signaling cascade involving many molecules begins. HER1/EGFR activation can produce a range of effects in tumor cells depending on the ligand involved and the dimer formed. Although not fully understood, certain signal transduction pathways are associated with specific cellular effects. The cellular effects of activation include increased cellular proliferation, invasion, metastasis, angiogenesis, and inhibition of apoptosis.1 There is evidence that somatic mutations in the TK domain of the HER1/EGFR gene increase activation in response to ligand binding.2 Finally, tumor cells driven by a HER1/EGFR pathway, particularly one involving an autocrine feedback loop, can become resistant to radiotherapy, chemotherapeutic agents or hormones, so making them resistant to conventional therapy.3,4 1. Woodburn J. Pharmacol Ther. 1999;82: 2. Lynch TJ, Bell DW, Sordella R, et al. New Engl J Med. 2004;350. 3. Knowlden JM, Hutcheson IR, Jones HE, et al. Endocrinology 2003;144: 4. Chakravarti A, Chakladar A, Delaney MA, et al. Cancer Res. 2002;62: JNK Abl PI3K Akt MAPK Proliferation, invasion, metastasis, angiogenesis, and inhibition of apoptosis Woodburn J. Pharmacol Ther. 1999;82: ; Lynch TJ, Bell DW, Sordella R, et al. New Engl J Med ;350; Knowlden JM, Hutcheson IR, Jones HE, et al. Endocrinology 2003;144: ; Chakravarti A, Chakladar A, Delaney MA, et al. Cancer Res. 2002;62:

38 HER1/EGFR Dysregulation in Tumors
Ligand overproduction (autocrine loop) Mutations conferring constitutive activation Defective internalization or downregulation Overexpression P P P P P P P P P P P P HER1/EGFR dysregulation takes several forms, one or all of which can be active in tumors, increasing receptor phosphorylation and, therefore, activation. Arguably the most important mechanism of HER1/EGFR dysregulation in tumor cells is the over-production of HER1/EGFR ligands, most often EGF and TGF-. HER1/EGFR overexpression as a result of gene amplification and/or protein over-production can increase receptor activation. Ligands can be over-produced by cells with dysregulated HER1/EGFR, producing an autocrine activation loop. This phenomenon is thought to be a vital step in the development of hormone-resistant tumors, particularly of the breast and prostate.1,2 HER1/EGFR mutations, most commonly EGFRvIII, result in ligand- independent, constitutive activity. There is evidence that EGFRvIII is associated with more aggressive tumors.3 Somatic mutations in the TK domain of the HER1/EGFR gene have been reported recently. Preliminary data suggest these mutations may cause enhanced receptor activation in response to ligand binding.4,5 Defective internalization or downregulation of the receptor can also cause abnormal signaling.6 1. De Miguel P, Royuela, Bethencourt R, et al. Cytokine. 1999;11: 2. Normanno N, Kim N, Wen D, et al. Breast Cancer Res Treat. 1995;35: 3. Lal A, Glazer CA, Martinson HM, et al. Cancer Res. 2002;62: 4. Lynch TJ, Bell DW, Sordella R, et al. New Engl J Med. 2004;350. 5. Paez JG, Janne PA, Lee JC, et al. Science, 29 April 2004 ( /science ). 6. Yang H, Jiang D, Li W, et al. Oncogene 2000;19: EGFR vII/III EGFR vI P = phosphate De Miguel P, Royuela, Bethencourt R, et al. Cytokine. 1999;11: ; Normanno N, Kim N, Wen D, et al. Breast Cancer Res Treat. 1995;35: ; Lal A, Glazer CA, Martinson HM, et al. Cancer Res. 2002;62: ; Lynch TJ, Bell DW, Sordella R, et al. New Engl J Med. 2004;350; Paez JG, Janne PA, Lee JC, et al. Science, 29 April 2004 ( /science ); Yang H, Jiang D, Li W, et al. Oncogene 2000;19:

39 Tumors with HER1/EGFR Dysregulation
Glioma Head and neck Breast Lung Esophagus Renal Gastric Colorectal Ovarian Pancreatic Many solid tumors have dysregulated HER1/EGFR.1 This association of HER1/EGFR and tumor development has been shown in hormone-sensitive tumors (breast and prostate), and also in tumors that are not hormone-dependent (e.g. head and neck, NSCLC, colon, ovarian, and glioma).2 HER1/EGFR dysregulation is associated with advanced disease and poor prognosis. 1. Salomon DS, Brandt R, Ciardiello F, et al. Crit Rev Oncol Hematol. 1995;19: 2. Woodburn JR. Pharmacol Ther. 1999;82: Bladder Cervical Prostate Salomon DS, Brandt R, Ciardiello F, et al. Crit Rev Oncol Hematol. 1995;19: Woodburn JR. Pharmacol Ther. 1999;82:

40 Common Approaches to Targeting HER1/EGFR
Various approaches are being investigated to target members of the HER family, particularly HER1/EGFR and HER2. These include receptor sub-type specific monoclonal antibodies (MAbs) and small-molecule TK inhibitors (TKIs), which target the HER axis either outside or inside the tumor cell, respectively. MAbs block the extracellular ligand-binding region of the receptor. Several MAbs are specific for either HER1/EGFR or HER2.1 Different antibody- based approaches use MAbs or HER ligands conjugated with cellular toxins.2 Small-molecule TKIs act at an intracellular level, inhibiting TK phosphorylation and preventing downstream receptor signaling. There are agents that inhibit HER1/EGFR specifically, HER1/EGFR and HER2, or all members of the HER family (pan HER-TK inhibitors).3-5 Agents are being developed to interfere with HER activity at a nuclear level by blocking signal transduction and/or translation. The most promising methods are antisense oligonucleotides, ribozyme-mediated DNA inhibition, and gene therapy.6 1. Slamon DJ, Leyland-Jones B, Shak S, et al. N Engl J Med. 2001;344: 2. Mendelsohn J, Baselga J. Oncogene. 2000;19: 3. Noonberg SB, Benz CC. Drugs. 2000;59: 4. Raymond E, Faivre S, Arman JP. Drugs. 2000;60(Suppl 1):15-23. 5. Arteaga C. J Clin Oncol. 2001;19:32s-40s. 6. Pedersen MW, Meltom M, Damstrup L, et al. Ann Oncol. 2001;12: P P TK inhibitors P Anti-ligand- blocking antibodies Ligand– toxin conjugates P Antibody– toxin conjugates Anti-HER1/EGFR- blocking antibodies Slamon DJ, Leyland-Jones B, Shak S, et al. N Engl J Med. 2001;344: ; Mendelsohn J, Baselga J. Oncogene. 2000;19: ; Noonberg SB, Benz CC. Drugs. 2000;59: ; Raymond E, Faivre S, Armann JP. Drugs. 2000;60(Suppl 1):15-23; Arteaga C. J Clin Oncol. 2001;19:32s-40s; Pedersen MW, Meltom M, Damstrup L, et al. Ann Oncol. 2001;12:

41 EGFR inhibitory K-ras Monoklonální protilátky
Tyrosinkinázové inhibitory ¯ Proliferation K-ras ­ Apoptosis ­ Sensitivity to radiotherapy ¯ Invasion Anti-HER1/EGFR monoclonal antibodies prevent ligand binding and subsequent receptor activation.1 Small-molecule TKIs inhibit the binding of ATP to the intracellular TK domain of the target receptor, blocking receptor phosphorylation and associated downstream signaling.2 Receptor inhibition using TKIs or antibodies inhibits cellular processes promoting tumor growth and progression, such as proliferation, angiogenesis, and metastasis, and normal control mechanisms, like apoptosis, are restored.1,2 HER1/EGFR inhibition also prevents tumor cells from evading damage by radiotherapy, so restoring or enhancing their sensitivity to this treatment.3 1. Etessami A, Bourhis J. Drugs Fut. 2000;25: 2. Moyer J, Barbacci EG, Iwata KK, et al. Cancer Res. 1997;57: 3. Harari PM, Huang SM. Semin Radiat Oncol. 2002;12(Suppl 2):21-26. ¯ Metastasis ¯ Adhesion ¯ Angiogenesis Etessami A, Bourhis J. Drugs Fut. 2000;25: Moyer J, Barbacci EG, Iwata KK, et al. Cancer Res. 1997;57: Harari PM, Huang SM. Semin Radiat Oncol. 2002;12(Suppl 2):21-26.

42 EGFR inhibitory vs. mutace K-ras
Monoklonální protilátky Tyrosinkinázové inhibitory ¯ Proliferation K-ras ­ Apoptosis ­ Sensitivity to radiotherapy ¯ Invasion Anti-HER1/EGFR monoclonal antibodies prevent ligand binding and subsequent receptor activation.1 Small-molecule TKIs inhibit the binding of ATP to the intracellular TK domain of the target receptor, blocking receptor phosphorylation and associated downstream signaling.2 Receptor inhibition using TKIs or antibodies inhibits cellular processes promoting tumor growth and progression, such as proliferation, angiogenesis, and metastasis, and normal control mechanisms, like apoptosis, are restored.1,2 HER1/EGFR inhibition also prevents tumor cells from evading damage by radiotherapy, so restoring or enhancing their sensitivity to this treatment.3 1. Etessami A, Bourhis J. Drugs Fut. 2000;25: 2. Moyer J, Barbacci EG, Iwata KK, et al. Cancer Res. 1997;57: 3. Harari PM, Huang SM. Semin Radiat Oncol. 2002;12(Suppl 2):21-26. ¯ Metastasis ¯ Adhesion ¯ Angiogenesis Etessami A, Bourhis J. Drugs Fut. 2000;25: Moyer J, Barbacci EG, Iwata KK, et al. Cancer Res. 1997;57: Harari PM, Huang SM. Semin Radiat Oncol. 2002;12(Suppl 2):21-26.

43 Onkogen K-ras Onkogen z rodiny ras – K-ras, N-ras, H-ras
Umístění na 12 chromosomu v pozici 12.1 Protein s GTPázovou aktivitou o velikosti 21 kDa Součást MAPK signální dráhy - účastní se přenosu signálu z vnějšího prostředí buňky do jádra a za fyziologických podmínek je aktivovaný receptorovými tyrosinkinázami, např. EGFR1

44 K-ras v onkologii Aktivační mutace K-ras genu v kodonu 12 a 13 Nová moderní cílená protinádorová léčiva EGFR inhibitory nízkomolekulární inhibitory tyrosinkináz (Gefitinib, Erlotinib) anti-EGFR monoklonální protilátky (Cetuximab, Vectibix) Nemalobuněčný karcinom plic (NSCLC), skvamocelulární karcinom hlavy a krku (HNSCC) a metastazující kolorektální karcinom (CrC) Kompletní či parciální remise je zaznamenána jen u relativně malého počtu pacientů (přibližně 10 %) Individualizace terapie – „Správnému pacientovi, správná léčba“

45 Biologická léčba Cílená individualizovaná léčba – targeting therapy – zasahuje specifický cíl – často signální molekuly nebo receptory zodpovědné za vznik onemocnění – důležitá znalost signálních drah – základní výzkum je předpokladem pro objevování novějších a účinnějších léčiv. Prediktivní faktory – negativní a pozitivní – predikují účinnost zvoleného léčiva u konkrétního pacienta.

46 Molecular Biology of the Cell, Fourth Edition
Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter 28/02/ pages MUDr. Josef Srovnal Laboratoř experimentální medicíny DK FN a LF UP Olomouc Tel:

47 Děkuji za pozornost