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THE MOLECULAR MECHANISM OF INVASIVENESS OF TUMOR CELLS

PRESENTED

BY ADESEMOWO ADETUNJI A.

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LOSS OF FUNCTION OF TUMMOR SUPPRESSOR GENES INHIBIT APOPTOSIS.

GAIN OF FUNCTION OF TUMMOR ONCOGENES LEADS TO UNCONTROLLABLE CELL PROLIFERATUON (CANCER).

PROMOTES INVASION OF CANCER CELLS THROUGH EGRF AND INTEGRIN SIGNALLING.

SUMMARIZED INTERACTIONS WITHIN A CELL

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INTRODUCTION

INVASIVENESS OF CANCER CELLS Tumor invasion is an intrinsic property cancer cell

progression to metastasis after intravasation into the blood vessels.

INVASIVENESS is a phenomenon which involves the dissemination of cancer cells through the destruction of the basement membrane.

Invasion is when the cancer growth goes into a new part within an organ, as the tumor gets larger and larger it spread through the organ.

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INVAPODIA or invasive feet are protrusions in the cancer cell membrane that are rich in actin and extend into the extracellular matrix (ECM).

The assembly of actin core structures, followed by the accumulation of matrix metalloproteinase promote ECM degradation.

These structures are very similar to the PODOSOMES formed by normal cells that need to cross tissue barriers such as

MACROPHAGES,

MONOCYTES,

OSTEOCLASTS that remodel tissue.

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However podosomes are short – lived and do not cause major degradation of ECM.

These assembly of actin core structures in invapodia of transformed tumor cells are associated with high levels of proteolysis and cell signaling

COMPONENTS OF INVASIVENESS

ACTIN REGULATION: Cofilin, Profilin, Thymosine – β4, Ar2/3, NWASP

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SIGNALLING ADAPTORS: SRC, CDC42, NCK1, P190RhoGAP, PKC, AMAP1

ADHESION: Integrins, Vinculin, Paxillin, Tensin, Immunoglobulin, Selectin, Ephrins, Chemokines

PROTEASES: MMPs, Cathepsins, Kallikerins, Plasmin, Elastase

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Src (SCHIMIDT RUPPIN A – 2 PROTEIN)

c-Src tyrosine kinase also known as proto-oncogene c-Src, is a nonreceptor tyrosine kinase protein that in humans is encoded by the SRC gene.

Src is a potent inducer of tumor invasion which would eventually progress to metastasis.

It includes an SH2 domain, an SH3 domain, and a tyrosine kinase domain.

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The binding of Arp2/3 to NWASP recruits CDC42/CIP4 to induce EGRF which activates the mutated Src through the integrin homing receptor present on the ECM (Extracellular Matrix).

The assembly of F – Actin is induced by Src. F – Actin recruits MMPs and proteases leading to tumor cell invasion.

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C – Src is regulated by phosphorylation of tyrosine 527 on its SH2 domain

Mutation of tyrosine 527 by tumor cells converts the proto – oncogen c – Src to Src. Initiate invasion and promote metastasis.

STABILITY OF INVAPODIA: The polymerization of F – Actin by

formins and fascin and barbed ends generated by cofilins stabilizes invapodia and promotes invasion of tumor cells.

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PROPERTIES OF PODOSOMES AND INVAPODIA

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Macrophages in Invasion and Intravasation

PODOSOMES AND INVAPODIA COOPERATING IN INVASION OF TUMOR CELLS.

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FAK P190RhoGap PKC AMAP1 PAXILLIN/CORTACTIN

K – RAS NCK1 EGRF CIP4 CDC42 NWASP Ar2/3

RAF INTEGRIN Vinculin Paxillin Tensin LAMININ

F – Actin core Dynamin Synatojanin MKP Cortactin Profillin MTI – MMP Endophilin Cofillin Thymosin Invadolysin TPA/UPA MMP – 9, MMP – 2 NWASP PLASMIN CIP4

Src

INVASIVENESSMETASTASIS

ALTERED GENE REGULATION

UNCONTROLLED CELL PROLIFERATION

PATHWAY TO INVASIVENESS

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SELCTIN IMMUNOGLOBULIN SUPERFAMILY (ICAM, PCAM etc)

INTEGRINS

EPHRINS CHEMOKINE RECEPTORS

CD44

AP

NF – KB

ETS

GLI

MTA

EGR

MMPS

CATHEPSINS

KALLIKERINS

PLASMIN

ELASTASE

DCC/SEMAPHORINS

TIMPSSERPINSCYSTATINS

E – CADHERIN

MAKP

AKAP

DMBTI

KISS

BRMS

NM23

LYMPHOCYTE/MONOCYTE

FOS,JUN,MAF,ATF

G-PROTEIN

BIMBCL-2

MYOSIN/ACTIN

SrC

F-ACTINENDOPHILIN

INVASIVENESS

APOPTOSIS

METASTASIS

FIBRONECTIN

TUMOR CELL SURVIVAL PATHWAY LEADING TO METASTASIS

BCL-2

HEDGHOG

SMO

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mitogen-activated protein kinase(MAPK) A-kinase anchor proteins(AKAP) Kisspeptins(KISS) Breast metastasis suppressor gene 1(BRMS) B-cell lymphoma 2(BCL – 2) Smoothened(SMO) Activating transcription factor(ATF1) Activator protein 1(AP – 1 ) Early growth response protein 1(EGRP) Metastasis-associated(MTA) E-twenty six(ETS) Guanine nucleotide-binding proteins(G – Protein)

ABBREVIATIONS AND THEIR MEANING

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Schmidt- Ruppin A-2(c – Src) Epidermal growth factor receptor(EGRF) Cdc42-interacting protein 4(CIP4) Cell division cycle 42(CDC42) Neutral Wiskott-Aldrich syndrome protein(NWASP) Melittin-related peptide (MRP)/(AR2/3) Protein kinase C ALPHA(PKC) Focal adhesion kinase(FAK) Rat sarcoma(RAS) Rapidly accelerated fibrosarcoma(RAF) Mitogen kinase protein(MKP)

ABBREVIATIONS AND THEIR MEANING

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C – Src (Schimidt Ruppin A – 2 ) NWASP (Wiskott – Aldrich syndrome protein)

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PROTEASES INVOLVED IN INVASIVENESS

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Malignant tumors secrete proteolytic enzymes to degrade basement membrane thus allowing invasive behavior.

CLASSES OF PROTEOLYTIC ENZYMES MATRIX METTALLOPRTEINASES: They are expressed in all forms of cancer and can be

classified according to their structure into eight different classes of MMPs.

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PROTEINASES OF FIBRINOLYTIC SYSTEM. The components of the fibrinolytic system is zymogene

plasmogen which is secreted in the liver and deposited in tumor in response to hyper permeability

The conversion of plasminogen to plasmin is regulated by two plasminogen activators TPA and UPA.

Plasmin facilitate tumor cell migration, invasion metastasis by degrading fibrin and other matrix protein directly by activating several metalloproteinases that additionally degrades extracellular matrix .

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Exposure of breast carcinoma cells to estrogens induces upper and uta which is required for the activation of plaminogen which is responsible for the degradation of the extracellular matrix.

In ovarian cancer lysophosphatidic acid may induce the secretion of UPA through EDG (endothelial cell differentiation gene).

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Invasion

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Gastric carcinomata also expresses high plasminogen activator

The UPA system is also associated with the development of melanoma.

CATHEPSINS They are all glycoproteins and contain essential cycteine

residue in their active site but they differ in their substrate specifities and PH stability.

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There are 11 cathepsins (B,C,F,H,K,L,O,S,V,W,X) and they are synthesized as inactive precursors consisting of a signal sequence a pro – peptide and a catalytic active mature region

Activation normally occur after cleavage of the amino terminal region.

Cathepsin D is regulated by intracellular growth factors, hormones and endogenous inhibitors and it is induced in hepatomata ,thyroid cancer, bladder cancer, gastric and colon carcinomata.

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Cathepsin B (Myeloid precursor protein secretase APPS). It is secreted in an inactive form of 42kD proform. Elevated levels of cathepsin B is occur in gliomata, lungs, pancreas, prostate, breast, and stomach carcinomata

KALLIKREINS They are a family of several single chain proteases. They

contain conserved serine proteases. Conserved disulfide bonds

The expression of kallikreins is regulated steriod hormones.

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ENZYME TARGET STRUCTURAL CLASS

TUMOR

MATRIX METALLOPROTEINASES

MMP – 1 (INTESTINAL COLLAVGENASES)

Collagen type 1,2,3,7 and 10

Simple hemopexin domain

Head and neck cancer

MMP – 2 Collagen 4,5,7,9,10 Gelatin binding Skin cancer, colon cancer, stomach cancer, ovarian cancer

MMP – 7 (Matrilysin, PUMP – 1)

Gelatin type 1,3,4,5

Minimal domain Gastric cancer and colon cancer

MMP – 9 92KD Collagenase type 4.

Collagen 4,5,7,9,10 Gelatin binding Skin cancer

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ENZYME TARGET STRUCTURAL CLASS

TUMOR

MMP – 10 Sromelysin

Laminin,fibronectin,proteoglycan core protein

Simple hemopexin domain

Head and neck cancer

FIBRINOLYTIC PROTEINASES

Urokinase Type Plasminogen Breast cancer melanoma

Plasminogen activator tissue type

Plasminogen Breast cancer

Plasminogen activator plasmin

Laminin type 4 collagen

Thrombin PAR – 1 Pancreas cancer, oral cancer

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PROTEASE AND THEIR PRECURSSORS INVOLVED IN INVASION

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ENZYME TARGET STRUCTURAL CLASS

TUMOR

CATHEPSINS

Cathepsin D Glioblastoma, hepatoma, melanoma and thyroid cancer

Cathepsin B Amyloid β pro - Urokinase

Glioblastoma, lung cancer

Cathepsin K Breast cancer, prostate cancer

Cathepsin S Elastin Astrocytoma

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ENZYME TARGET STRUCTURAL CLASS

TUMOR

OTHER PROTEASES

Elastase Elastin Colorectal carcinoma, breast cancer

PROTEASE INHIBITORS

TIMP – 1 92 kD Collagenase Type 4 intestinal collagenase stromelysin

TIMP – 2 72 kD Collagenase Type 4

PAI – 1 Plaminogen activator

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SURVIVAL DURING INVASION The binding of integrin (alpha 5,beta 1) to fibronectin induces

the expression of BCL – 2, which protect cells from apoptosis during invasion

BIM and BMF released from the cytoskeleton of normal cells, through the interaction between myosin and actin on the contrary inhibits the anti – anoikis properties of BCL – 2 and this initiates programmed cell death (apoptosis)

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FAK signaling is also implicated in promoting cell survival through its substrate PKB (Phosphtidylinositol 3 – kinase)

Cell – cell interaction through cadherin protect from apoptosis

through a pathway that depends on cytoskeletal integrity.

39Hanahan & Weinberg 2000

Summary of 30 years of research (1971-2001)

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MOLECULAR BIOLOGY & INFORMATICS

Biyoinformatik

~30.000 genes~300.000 protein

~3.000.000 interaction1 human cell

~3.000.000.000 bpDNA

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