From Signal Transduction From Signal Transduction to Targeted Therapy to Targeted Therapy

(Fall 2010)(Fall 2010)

Pin Ling ( 凌 斌 ), Ph.D.

Department of Microbiology & Immunology, NCKU

ext 5632

lingpin@mail.ncku.edu.tw

Outline Signaling Transduction

- Definition- History- Mechanisms- Example

Targeted Therapy - Mechanisms

- Examples- Current Trend

Your involvement is the key to success in this lecture.

What is Signaling Transduction?What is Signaling Transduction?

• Conversion of a signal from one physical or chemical form into another.

• The process initiated by recognition a Signal by a Sensor (receptor, kinase or enzyme) in the cell, then converting to one or more cellular responses through a series of signal

transmission.

ReceptorsReceptors

Signal Signal TransduceTransduce

rsrs

EffectorsEffectors

A simple scheme of signal A simple scheme of signal transductiontransduction

Fig 15-1 Adopted from Molecular Biology of The Cell

Q: Who first gets the idea about “ Signal Transduction”?Molecules involved in this

process, called Signaling Molecules

History of signaling transductionHistory of signaling transduction

Adopted from Nobelprize.org

Rodbell’s findings

Adopted from Nobelprize.org

Gilman’s findings

Adopted from Nobelprize.org

Adopted from Molecular Cell Biology

Current view of GPCR signalingCurrent view of GPCR signaling

A simple scheme of signal transduction

Fig 15-1 Adopted from Molecular Biology of The Cell

Receptors

Signal Transducers

Effectors

Four types of surface receptorsFour types of surface receptors

Adopted from Molecular Cell Biology

GPCR

Ion Channel

Receptor w/o Enzyme

Receptor w/ Enzyme

Adopted from Molecular Cell Biology

Four common second messengersFour common second messengers

cAMP is the first 2cAMP is the first 2ndnd Messenger Messenger

Adopted from Nobelprize.org

(1st messenger)(2nd messenger)

A simple scheme of signal transduction

Fig 15-1 Adopted from Molecular Biology of The Cell

Receptors

Signal Transduce

rs

Effectors

Two types of signal transducers

Enzymatic proteins: Kinase, GTPase,….etc

Non-Enzymatic proteins: Adaptors, Scaffolds,...etc

Post-Translation Modifications (PTMs): Phosphorylation…..

Protein-Protein Interactions,Signalsome Formation

Two major biochemical events in signal transduction

Examples of enzymatic Examples of enzymatic proteinsproteins

Adopted from Molecular Cell Biology

Adaptors in signal Adaptors in signal transductiontransduction

Adopted from Molecular Cell Biology

Ras activation following EGFR signaling

Adopted from Molecular Cell Biology

Ras activates the MAPK/ERK pathway

Adopted from Cell Signaling

A simple scheme of signal transduction

Fig 15-1 Adopted from Molecular Biology of The Cell

Receptors

Signal Transducers

Effectors

Types of Post-Translation Modifications

PhosphorylationMethylationAcetylation

UbiquitinationSumoylation

Chemical groups

Small peptides

PalmitoylationMyristoylation Lipid groups

Glycosylation Sugar groups

Features of Post-Translation Modifications

1. Most are Reversible

2. Regulate Protein Activity, Protein Localization, Protein Interaction,……etc.

3. Focus on “Protein Phosphorylation” today

Protein Protein PhosphorylationPhosphorylation

Adopted from Nobelprize.org

Activation of a enzyme by phosphorylation

Mechanism of Phosphorylation by cAPK (PKA)

Adopted from Molecular Cell Biology

G. Manning et al., Science. 2002, 298:1912-34.

Human Kinome

1. 518 protein kinases

2. Tyr & Ser/Thr kinases

3. Involve many processes

4. Dysregulation => diseases

5. Targets for therapy

(Charles Swyers, Nature 2004)

Examples of kinase-associated diseases

Post-translational modifications of human nucleosomal histones

Modular interaction domains Modular interaction domains in in

signaling transductionsignaling transduction

(Pawson et al, Science 2003)

Check more details in BIND database(Biomolecular Interaction Network Database)www.bind.ca

             Cell. 2004 Jan 23;116(2):191-203.

Specificity in signal transduction: from phosphotyrosine-SH2 domain interactions to complex cellular systems.

Pawson TonySamuel Lunenfeld Research Institute, Mt. Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada. pawson@mshri.on.ca

Science 18 April 2003: Vol. 300. no. 5618, pp. 445 – 452

Assembly of Cell Regulatory Systems Through Protein Interaction Domains

Tony Pawson1,2* and Piers Nash1

1 Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada.2 Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada. * To whom correspondence should be addressed. E-mail: pawson@mshri.on.ca

Signaling Signaling SpecificitySpecificity

Multiple signaling cascades form signaling networks

Cell. 2000 Oct 13;103(2):193-200.

Curr Opin Cell Biol. 2002 Apr;14(2):173-9.M. Synder et al,

Approaches to studying signaling networks

Trends in TherapiesTrends in Therapies

1. Gene Therapy – genetic diseases, cancer,…etc

2. Cell Therapy – degenerative diseases (Alzheimer, Myocardial disorders….etc)

3. Targeted Therapy – cancer, immune disorders,…etc

=> Each has its pros and cons.

Signaling Transduction => Molecular Targets Signaling Transduction => Molecular Targets => Targeted Therapy=> Targeted Therapy

Fig 15-1 Adopted from Molecular Biology of The Cell

Receptors

Signal Transducers

Effectors

Dysregulation of signaling Dysregulation of signaling molecules leads to disordersmolecules leads to disorders

A simple scheme of signal A simple scheme of signal transductiontransduction

Q1: How to do targeted therapy?Q1: How to do targeted therapy?

Two major biochemical events in signal transduction:

(1) Post-Translation Modifications: protein phosphorylation

(2) Protein-Protein Interactions: ligand- receptor, protein-dimeriztion

Molecules designed to block these two biochemical events

Abl, BCR-Abl, & Abl, BCR-Abl, & Chronic Myelogenous Leukemia (CML)Chronic Myelogenous Leukemia (CML)

Nat Rev Cancer. 2005 Mar;5(3):172-83.

Nat Rev Cancer. 2005 Mar;5(3):172-83.

Leukemogenic signaling of BCR-Abl

Development of Chronic Myelogenous Leukemia

(CML)

Nat Rev Cancer. 2005 Mar;5(3):172-83.

Copyright ©2001 AlphaMed Press

Mauro, M. J. et al. Oncologist 2001;6:233-238

Figure 1. Schematic representation of the mechanism of action of STI571

Gleevec (STI 571, Imatinib): A Small Molecule with a Big Impact

Q2: How to deal with drug resistance ?Q2: How to deal with drug resistance ?

Some CML patients develop resistance or relapse

to targeting small molecule (Imatinib).

(1) Develop modified drug (2nd generation kinase

inhibitor)

(2) Combination therapy

2nd generation TKI -Imatinib-like compound

J. Cortes et al Blood, 2009

IC 50, lower is better.

Molecules for targeted therapies

(1)Small molecules: target the ATP binding site or other regions in protein kinase domain, e.g. Gleevec (to BCR-Abl)

(2) Monoclonal Abs: target receptors, cytokines, other surface proteins,

e.g. Herceptin (to Her), Erbitux (to EGFR)

(3) Others: Decoy receptors (soluble CTLA4-Ig), Vaccines, RNAi,..etc

Targeting drugs in clinical trialsTargeting drugs in clinical trials

Ab-mediated signaling inhibitionAb-mediated signaling inhibition

Adopted from Nature Biotechnology  23, 1147 - 1157 (2005)

Approved mAbApproved mAbCancer Cancer

therapeuticstherapeutics

SummarSummaryy1. Signaling transduction is essential for cells to

communicate with environmental stimuli.

2. It usually includes three major components: Receptor, Transducer, & Effector.

3. Two key biochemical events during signaling transduction: PTMs & Protein Interactions

4. Dysregulation of signaling molecules perturbs cellular processes then leading to disease develpoment.

5. Targeted therapy are mostly based on targeting two biochemical events.

Kinase: www.kinase.com (seq, evolution & kinomes)

Protein kinase resource: www.kinasenet.org (kinase structure)

Alliance for cell signaling: www.signaling-gateway.org

Phosphosite database: www.phosphosite.org (in vivo phosphorylation sites)

Websites for signaling Websites for signaling transductiontransduction

HomeworHomeworkk

Gleevec has also been found to effectively treat other

cancer cells such as gastrointestinal stromal tumors

(GIST). However, scientists found no mutation of Abl

kinase in these tumor cells. Please explain the

underlying mechanism of how Gleevec is still working

in this kind of cancer cells even without c-Abl mutation.

B. Druker , Cancer Cell, 2002

22ndnd generation TKI generation TKI STI 571-like compoundSTI 571-like compound

Kantarjian et al. Nature Reviews Drug Discovery 5, 717–718 (September 2006) | doi:10.1038/nrd2135