Have Details about the various signaling pathways and signaling molecules and their role in solid tumors.

1. DR. HARISINGH GOUR CENTRAL UNIVERSITY, SAGAR
Made by:-
Sunny Rathee
Subject – Molecular Biology And Genetic Engineering
DEPARTMENT OF PHARMACEUTICAL SCIENCES
1

2. Flow of Presentation
2
1. Introduction to Cell Signaling,
2. Receptor Activation,
3. Classification of signaling pathways,
4. Types of signaling,
5. Need of cell signaling,
6. Stages of cell signaling-
A) RECEPTION- Includes Intracellular receptors and the
receptors in plasma membrane,
B) TRANSDUCTION- Includes various pathways of
secondary messengers like-cAMP, cGMP, IP3-DAG and
role of calcium as secondary messenger,
7. JAK-STAT PATHWAY,
8. MAP-KINASE PATHWAY,
9. ROS PATHWAY,
10.VEGF PATHWAY,
11. SOLID TUMOR,
11.REFERENCES

3. INTRODUCTION TO CELL SIGNALING
 Cell signaling: A biological mechanism that occurs in cells which
gives cells an ability to receive or generate the signals in response to
their surrounding environment.
 Cell to cell communication between cells is mediated by extra-
cellular signal molecules. Some of those operate over long distances.
Others signal only to immediate neighbouring cells.
 Signaling - Cell-cell communication or communication of the
environment to the cells interior via signals.
 Signal transduction -Process of converting extracellular signals into
intra- cellular responses.
 Receptors - Bind specific ligands. Transmit signals to intracellular
targets.
Different receptors can respond differently to the same ligand.

4. Receptor
activation
Receptor
activation
CELLULAR
RESPONSE
Permeability
Metabolism
Secretory
activity
Rate of
proliferation
and
differentiation
Contraction

5. CLASSIFICATION OF SIGNALING PATHWAYS
CONTACT
DEPENDENT
(JUXTACRINE
SIGNALING)
SYNAPTIC
(BETWEEN
NEURONS)
SIGNALING
PATHWAYS

6. CONTACT DEPENDENT SIGNALING
Also known as Juxtacrine signalling or Notch mediated Juxtacrine
signalling.
Its of 3 types-
1) Membrane ligand(protein, lipid) & membrane protein of 2 adjacent
cells interact with each other.
2) Links Intracellular compartment of 2 adjacent cells.
3) Extracellular matrix glycoprotein combines with membrane protein.
SYNAPTIC CELL SIGNALING(BETWEEN
NEURONS)
In synaptic cell signaling, Nerve cells send signals through synapse
( Junction between 2 nerve cells) where, signal transduction occurs.
Example of Synaptic cell signaling- Paracrine signaling.

7. Cells communicate by means of extracellular signaling molecules that are
produced and released by signaling cells. These molecules recognize and
bind to receptors on the surface of target cells where they cause a cellular
response by means of a signal transduction pathway.
Depending on the distance that the signaling molecule has to travel, we
can talk about three types of signaling:
TYPES OF SIGNALING
1) ENDOCRINE SIGNALING
In endocrine signaling, signaling
molecules, called hormones, act on target
cells distant from their site of synthesis by
cells of endocrine organs. In animals, an
endocrine hormone usually is carried by the
blood from its site of release to its target.

8. In paracrine signaling the signaling
molecule affects only target cells in
the proximity of the signaling cell.
An example is the conduction of an
electric signal from one nerve cell
to another or to a muscle cell. In
this case the signaling molecule is a
neurotransmitter.
In autocrine signaling cells respond to molecules they produce themselves.
Examples include many growth factors. Prostaglandines, lipophilic
hormones that bind to membrane receptors, are often used in paracrine
and autocrine signaling. They generally modulate the effect of other
hormones.
2) PARACRINE SIGNALLING
3) AUTOCRINE SIGNALING

9. Once a signaling molecule binds to its receptor it causes a
conformational change in it that results in a cellular response. The same
ligand can bind to different receptors causing different responses (e.g..
acetylcholine). On the other hand, different ligands binding to different
receptors can produce the same cellular response (e.g. glucagon,
epinephrine).

10. No cell can live in isolation, must interact with environment.
In multicellular organisms, cells must communicate
with each other.
Growth involves intricate signaling.
Same with Differentiation.
Even Metabolism requires signaling.
WHAT IS NEED OF CELL SIGNALING

11. Earl W. Sutherland, discovered how hormone epinephrine acts on cells,
suggested that cells receiving signals went through three processes:
STAGES OF
CELL
SIGNALING
TRANSDUCTION
OF SIGNAL
RECEPTION OF
SIGNAL
RESPONSE TO
SIGNAL

12. Highly specific binding of signaling molecule to its receptor.
Binding leads to conformational change in receptor often initiation
of signal transduction.
Most receptors are plasma membrane proteins.
1) RECEPTION
RECEPTION TRANSDUCTION RESPONSE
Receptor
Signal
molecule
Relay molecules in a signal transduction
pathway
Activation
of cellular
response
CYTOPLASM
Plasma membrane
EXTRACELLULAR
FLUID

13. Some receptors present in the cytosol or nucleus.
 Small or hydrophobic chemical messengers can cross plasma
membrane and activate intracellular receptors.e.g. steroid and thyroid
hormones.
 An activated hormone-receptor complex can act as a transcription
factor.
A) INTRACELLULAR RECEPTORS
B) RECEPTORS IN PLASMA MEMBRANE
Water-soluble signaling molecules bind to receptor proteins present in
plasma membrane.
Three main types of membrane receptors:
1. G-protein-linked receptors.
2. Enzyme coupled cell surface receptors.
3. Ion channel receptors.

14.  Also known as seven-transmembrane domain receptors,
7TM receptors, heptahelical receptors, and G-protein linked
receptors (GPLR).
 These constitute a large protein family of receptors that
sense molecules outside the cell and activate inside signal
transduction pathways and, ultimately, cellular responses.
 Coupling with G proteins, they are called seven-
transmembrane receptors because they pass through the cell
membrane seven times.
1
4
G-PROTEIN COUPLED
RECEPTORS(GPCRs)

15.  The ligand that binds and activates these receptors
includes-
1. Light-sensitive compounds,
2. Odors, Pheromones, Hormones,
3. And neurotransmitters, and vary in size from small
molecules to peptides to large proteins.
 G protein–coupled receptors are involved in many diseases,
and are also the target of approximately 40% of all modern
medicinal drugs.

16. 1
6
G-Protein coupled receptors

17.  It is known that in the inactive state, the GPCR is bound to a
heterotrimeric G protein complex.
 Binding of an agonist to the GPCR results in a conformation change
in the receptor that is transmitted to the bound Gαsubunit of the
heterotrimeric G protein.
 The activated Gα subunit exchanges GTP in place of GDP which in
turn triggers the dissociation of Gα subunit from the Gβγ dimer and
from the receptor.
MECHANISM OF GPCRs
 The dissociated Gα and Gβγ subunits interact with other intracellular
proteins to continue the signal transduction cascade.
 While the freed GPCR is able to rebind to another heterotrimeric G
protein to form a new complex that is ready to initiate another round
of signal transduction.

18. G-PROTEIN
LINKED
RECEPTORS
Type of plasma
membrane receptor.
G-Protein act as an
on/off switch
Enzyme Coupled
Receptors
Transfers phosphate
groups from high
energy donor
molecules like ATP, to
specific substrates.
Example- Receptor
Tyrosine Kinase(RTKs)
TYPES OF MEMBRANE RECEPTORS

19. Ion Channel
Receptors
It acts as a Gated
Channel
On Binding signal
molecules allow specific
ions such as Na+ or Ca2+,
to pass through the
receptor channel
Signal
molecule
(ligand)
Gate
closed
Ions
Plasma
membrane
Ligand-gated
ion channel receptor
Gate open
Cellular
response
Gate closed
MECHANISM OF LIGAND GATED ION CHANNEL RECEPTORS

20. May involve multiple steps-
1. Helps in amplification& Transmission of a signal.
2. Provides more opportunities for coordination and regulation.
3. Molecules that relay a signal from receptor to response are mostly
proteins
Transduction includes- Secondary Messengers.
2) TRANSDUCTION
Second messengers are intracellular signaling molecules released by
the cell to trigger physiological changes such as proliferation,
differentiation, migration, survival, and apoptosis.
 Secondary messengers are therefore one the initiating components of
intracellular signal.
TRANSDUCTION MEDIATED BY VARIOUS SECONDARY
MESSENGERS

21. 8
SIGNAL TRANSDUCTION MECHANISMS

22. HYDROPHOBIC
Diacylglycerol
Phosphatidylinositols
HYDROPHILIC
cAMP
cGMP
IP3 & Calcium
TYPES OF SECONDARY MESSENGERS

23. cAMP
Pathway
Calcium as
Secondary
Messenger
Eicosanoids
IP3-DAG
Pathway
cGMP
Pathway
VARIOUS PATHWAYS OF SECONDARY
MESSENGERS

24. 1) cAMP PATHWAY
Ligands : EpinephrineAch.
 Primary Effector :Adenyl cyclase.
 Secondary messenger : cAMP
 Most widely used second messengers.
 Discovered by Earl W. Sutherland Jr.
 Formed from ATP by Adenylyl Cyclase, in response to an
extracellular signal.
 Many signal molecules trigger formation of cAMP.
 cAMP usually activates Protein Kinase A, which phosphorylates
various other downstream proteins.

25. cAMP
A
TP
Second
messenger
G-protein-linked
receptor
First messenger
(signal molecule
such as epinephrine)
G protein
Adenylyl
cyclase
Protein
kinaseA
Cellular responses
GTP
CYCLIC AMP PATHWAY

26. 1. The ligand binds to the receptor,
altering its conformation and
increasing its affinity for the G
protein to which it binds.
2. The G subunit releases its GDP,
which is replaced by GTP.
3. The α subunit dissociates from
the G complex and binds to an
effector (in this case adenylyl
cyclase), activating the effector.
4. Activated adenylyl cyclase
produces cAMP.
THE MECHANISM OF RECEPTOR-MEDIATED ACTIVATION
AND INHIBITION OF CAMP

27. 5. The GTPase activity of G-
protein hydrolyzes the bound
GTP, deactivating G-complex.
6. G-protein reassociates with G-
complex, reforming the trimeric
G protein, and the effector
ceases its activity.
7. The receptor has been
phosphorylated by a GRK (G-
Protein coupled receptor kinase).
8. The phosphorylated receptor has
been bound by an arrestin
molecule, which inhibits the
ligand-bound receptor from
activating additional G proteins.

28. 2) cGMP PATHWAY
Ligands : ANP & NO
 Primary Effector : Guanylate cyclase
 Secondary messenger : Cgmp.
 cGMP is synthesized from the nucleotide GTP using the enzyme
Guanylyl cyclase.
 Nitric Oxide(NO) stimulates the synthesis of cGMP.
 Many cells contain a cGMP – stimulated protein kinase that contains
both catalytic and regulatory subunits.
 Some of the effects of cGMP are mediated through Protein Kinase G
(PKG).
 cGMP pathway mainly occurs in kidney(nephron cells).
 cGMP serves as the secondary messenger for-
1. Nitric Oxide(NO)
2. The response of the rods of retina to light.

29. cGMP PATHWAY

30. 3) PHOSPHATIDYLINOSITOL-DERIVED SECONDARY
MESSENGERS
 Phosphatidylinositol ( PI) is a negatively charged phospholipid and
a minor component in eukaryotic cell membranes.
 The inositol can be phosphorylated to form
 Phosphatidylinositol-4-phosphate (PIP)
 Phosphatidylinositol-4,5-bis-phosphate (PIP2)
 Phosphatidylinositol-3,4,5-trisphosphate (PIP3)
 Intracellular enzyme phospholipase C (PLC),hydrolyzes
PIP2 which is found in the inner layer of the plasma membrane.
Hydrolysis of PIP2 yields two products:
 Diacylglycerol (DAG)
 Inositol-1,4,5-trisphosphate (IP3)
PHOSPHO
INOSITIDES.

31. DIACYLGLYCEROL
 Diacylglycerol stimulates protein kinase C activity by
greatly increasing the affinity of the enzyme for calcium
ions.
 Protein kinase C phosphorylates specific serine and
threonine residues in target proteins.
 Known target proteins include calmodulin, the glucose
transporter, HMG-CoA reductase, cytochrome P450 etc.

32. INOSITOL TRIPHOSPHATE, IP3
 This soluble molecule diffuses through the cytosol and
binds to receptors on the endoplasmic reticulum
causing the release of calcium ions (Ca2+) into the
cytosol.
 The rise in intracellular calcium triggers the response.
 Example: the calcium rise is needed for NF-AT (the
"nuclear factor of activated T cells") to turn on the
appropriate genes in the nucleus.

33. MODE OFACTION
 Peptide and protein hormones like vasopressin, TSH, and
neurotransmitters like GABA bind to GPCRs
 This activate the intracellular enzyme phospholipase C
(PLC).
 PLC in turn cleaves PIP2 to yield two products – DAGand
IP3.
 Both of these products act as second messengers.
 So, the cleavage of PIP2 by PLC is the functionalequivalent
of the synthesis of cAMP by adenylyl cyclase.

34. FORMATION OF DAG & IP3

35. IP3-DAG SIGNAL TRANSDUCTION
PATHWAY

36.  Ca2+ is an important secondmessenger.
 Cells tightly regulate Ca2+ concentration.
 A signal may trigger an increase in Ca2+ incytosol.
 Pathways leading to the release of Ca2+ involve inositol triphosphate
(IP3) and diacylglycerol (DAG) as second messengers.
 Calcium ions are mainly responsible for many important physiological
functions including muscle contraction, fertilization, and
neurotransmitter release.
 example- IP3- GATED CALCIUM CHANNEL.
4) CALCIUM IONS AND IP3 (IONOSITOL TRI-
PHOSPHATE)

37. CALCIUM IONS
 Many cells respond to extracellular stimuli by altering their
intracellular calcium concentration.
 Ca++ acts as a second messenger in two ways:
 It binds to an effector molecule, such as an enzyme,
activating it;
 It binds to an intermediary cytosolic calcium binding
protein such as calmodulin.
 The binding of Ca++ causes profound conformational changes in
calmodulin that increase calmodulin`s affinity for its effector
molecules.
 Calmodulin, when activated, causes contraction of smooth
muscles.

38. CYTOSOL
Ca2+
Endoplasmic
reticulum (ER)
IP3-gated
calcium channel
IP (second
3
messenger)
DAG
PIP2
G-protein-linked
receptor Phospholipase C
(first messenger)
G protein
EXTRACELLULAR Signal molecule
FLUID
GTP
Ca2+
(second
messenger)
Various
proteins
activated
Cellular
re-
sponses
CALCIUM AND IP3 (INOSITOL TRI-
PHOSPHATE)

39. JAK-STAT PATHWAY(Occurs in cytoplasm of cell)
The JAK-STAT (Janus kinase-signal transducer and activator of
transcription) signaling pathway transmits information from chemical
signals outside the cell, which causes DNA transcription and activity in
the cell.
The JAK-STAT system is a major signaling alternative to the second
messenger system.
It consists of three main components:
1. Receptor,
2. JAK-Janus kinases,
3. STAT- Signal transducer and activator of transcription.
Types of JAK Protein-
A) Janus kinase 1(Interferon gamma signaling)
B) Janus kinase 2 (most important)
C) Janus kinase 3 (lymphocyte development)
D) Tyrosine kinase 2

40. JAK-STAT SIGNALING PATHWAY

41. MECHANISMS AND CONSEQUENCES OF JAK-STAT
SIGNALING IN THE IMMUNE SYSTEM
 The binding of the ligand to the receptor triggers activation of JAKs.
 With increased kinase activity, they phosphorylate tyrosine residues
on the receptor and create sites for interaction with proteins that
contain phosphotyrosine-binding SH2 domains.
 STATs possessing SH2 domains capable of binding these
phosphotyrosine residues are recruited to the receptors, and are
themselves tyrosine-phosphorylated by JAKs.
 These phosphotyrosines then act as binding sites for SH2 domains of
other STATs, mediating their dimerization. Different STATs form
hetero- or homodimers.
 Activated STAT dimers accumulate in the cell nucleus and activate
transcription of their target genes.

42. DRUGS TARGETING JAK-STAT
PATHWAY
1) Drugs that
are used to
turn down the
immune
response.
Example-
Basiliximab.
2) Drugs that
inhibit kinase
activity of JAK.
Example-
Ruxolitinib and
Tofacitinab
(used in
treatment of
Rheumatoid
arthritis) .
3) Drugs that
inhibit JAK1.
Example-
Oclacitinib
(Used for
treatment of
allergic
dermatitis).

43. ROLE OF JAK-STAT SIGNALING IN
CANCER
The tyrosine kinase JAK and its downstream target STAT respond to
cytokine signaling in cells.
In response to cytokines, JAK itself is phosphorylated, leading to its
activation. The activated JAK kinase then phosphorylates specific
STATs.
STAT proteins dimerise and translocate into the nucleus upon
phosphorylation by JAK, where they bind to DNA and regulate
transcription.
Overactivation of the JAK-STAT Pathway can cause cancer by
bypassing apoptosis and cell cycle checkpoints.
 Unphosphorylated STAT is also found in the nuclei and mitochondrial
cells that are not stimulated by cytokines.
Mitochondrial STAT upregulates cellular respiration and can promote
oncogenic transformation.

44.  Unphosphorylated nuclear STAT binds to HP1 ALPHA and stabilizes
heterochromatin. STAT5A in colon cancer cells acts as a tumour
suppressor via this mechanism.
 Nuclear JAK2 is a histone tyrosine kinase. Phosphorylation of histone
3 tyrosine 41 displaces HP1 ALPHA / CBX5 from chromatin and
contributes to tumourigenicity.
• There are mainly 2 types of STAT –
A) STAT 4 (Helps in NK cells activation)
B) STAT 5 (Helps in WBC Formation)
Clinical Significance of JAK-STAT Signaling-
 Disrupted or disregulated JAK-STAT functionality can result in
immune deficiency syndrome and cancer.
 An advantage of JAK inhibitors over receptor blocking drugs is that
they are small molecule drugs that can be taken orally.

45. MITOGENE ACTIVATED PROTIEN
KINASE (MAPK)
PATHWAY/RAF PATHWAY
 Mitogene:-It is a chemical substance that encourages a cell to
commence cell division, triggering mitosis. A mitogen is usually some
form of a protein.
 Signal transduction pathways MAPK mitosis.
 Mitogens act primarily by influencing a set of proteins which are
involved in the restriction of progression through the cell cycle.
 Only the G1 checkpoint is controlled most directly by mitogens.
 The point where mitogens are no longer needed to move the cell cycle
forward is called the "restriction point" and depends on cyclins to be
passed.

46.  Ubiquitin:-It is a small (8.5kDa) regulatory protein
found in most tissues of eukaryotic organisms.
 The addition of ubiquitin to a substrate protein is called
ubiquitination or less frequently ubiquitylation.
 Ubiquitination affects proteins in many ways: it can mark
them for degradation via the proteasome, alter their cellular
location, affect their activity, and promote or prevent protein
interactions.
 Kinase:-It is an enzyme that catalyzes phosphorylation
reaction.
And kinase helps in inhibiting the ubiquitination.
 MAP-K Pathway Occurs in various cellular compartments
like cytoplasm, cytoplasmic organelles like mitochondria,
endosomes/lysosomes, and particularly in the nucleus.

47. ROLE OF MAP-K PATHWAY IN HEMATOPOIETIC
STEM CELL SUPPRESSION

48. MAP kinases are intermediates in signal transduction
pathways that are initiated by many types of surface
receptors.
The targets of MAPK are located within many
cellular compartments.
MAPK provide a physical link in the signal transduction
pathway from the cytoplasm to the nucleus.
Each MAPK pathway contains a three tiered kinase cascade
comprising a MAP kinase kinase kinase (MAPKKK,
MAP3K, MEKK or MKKK), a MAP kinase kinase
(MAPKK, MAP2K, MEK or MKK) and the MAPK

49. Activation of
Apoptosis
signal-
regulated
kinase 1
(ASK1)
Inhibition of
MAPK
phosphatases
Regulation
&
Activation
of MAPK
pathway
REGULATION AND ACTIVATION OF
MAPK PATHWAY

50. MAP-K SIGNALING PATHWAY

51. ROS PATHWAY(Reactive Oxygen Species in
Signal Transduction and its applications)

52. ROLE OF ROS IN CELL SIGNALING AND
CANCER
REACTIVE OXYGEN SPECIES (ROS)
HOMEOSTASIS AND REDOX
REGULATION IN CELL SIGNALING
REGULATION OF MAPK
SIGNALING PATHWAYS
REGULATION OF P13K
SIGNALING PATHWAYS
REGULATION OF NRF2
SIGNALING PATHWAYS
APPLICATIONS FOR DRUGS
TARGETED
TO INCREASE ROS IN CANCER
TREATMENT
MILTIRONE, CURCUMIN
LONGIKAURIN, APIGENIN
BRUSATOL

53. VEGF PATHWAY IN CANCER CELLS(VASCULAR
ENDOTHELIAL GROWTH FACTOR)
• Originally described as endothelial cell-specific mitogen
(Abraham and Schilling, 1989).
• VEGF is a subfamily of growth factors, to be specific, the
platelet derived growth factor family of cystine-knot growth
factors.
• Native VEGF is a basic, heparin – binding, homodimeric
glycoprotein of molecular weight (45kDa).
• VEGF Plays a role in normal physiological functions such as
Bone marrow formation, Hepatopoiesis, wound healing,
and development.
• VEGF- First identified in guinea pig, hamsters, and mice.
• Crystal structure of VEGF –first at 2.5A resolution
described by Christinger and De Vos (1996-1997).

54. COMPARISON BETWEEN
CANCEROUS(HYPOXIC CELLS) AND
NORMALCELLS BY VEGF SECRETION LEVELS
FUNCTIONS- AG01- A MULTI-TARGET TYROSINE KINASE RECEPTOR INHIBITOR
Mir-92 – Stimulates VEGF BY INHIBITING VON HIPPEL LINDAU GENE PRODUCT.

55. TUMOURS

56. DEFINITION:
 A neoplasm is defined as “ abnormal mass of tissue, the
growth of which exceeds and is uncoordinated with that of
the normal tissues and persists in the same excessive manner
after the cessation of the stimuli which evoked the change.
 The neoplasm is defined as “a mass of tissue formed as a
result of abnormal, excessive, unco-ordinated and
autonomous and purposeless proliferation of cells.
 A swelling of a part of the body, generally without
inflammation, caused by an abnormal growth of tissue,
whether benign or malignant.

57. TUMORS (CHARACTERISTICS):
TUMORS
1) SIZE-
SMALL IN
SIZE AND
GROWS
SLOWLY
2) SHAPE- WELL
DEFINED,
SPHERICAL IN
SOLID ORGANS
AND POLYPLOID
IN NATURE
3) SURFACE-
SMOOTH AND
CAPSULATED
4) CUT SURFACE –
IT IS USUALLY SOLID
HOMOGENOUS
AND MAY BE
CYSTIC WITH NO
NECROSIS AND
HEMORRHAGE.

58. Examples of solid benign tumors
Fibroadenoma,
breast lipoma
Leiomyoma, uterus

59. HYPERPLASIA
 Excited by a stimulus
 Reversible, i.e. cell
proliferation stops if the
stimulus abates.
 Proliferated cells are normal-
shaped.
 May be useful as
compensatory hyperplasia.
NEOPLASIA
 A stimulus may not be
detected.
 Irreversible, i.e. cell
proliferation is unlimited &
progresses , even if any
evoking stimulus has
stopped.
 Proliferated cells are
abnormal-shaped (in
malignant neoplasia)
 Harmful
Differences between Hyperplasia and Neoplasia:

60. DIFFERENCES BETWEEN BENIGN AND
MALIGNANT TUMORS
BENIGN MALIGNANT
Spread LOCALIZED LOCAL &
DISTANT SPREAD
Rate Of Growth SLOW RAPID
Boundaries CIRCUMSCRIBED,
OFTEN ENCAPSULATED
IRREGULAR,
NON ENCAPSULATED
Relationship To
Surrounding
Tissue
COMPRESS
SURROUNDING NORMAL
TISSUES
INVADES AND DESTROY
SURROUNDING NORMAL
TISSUE
Effects PRODUCED BY PRESSURE
ON SURROUNDING
STRUCTURES AS VESSELS,
NERVES AND ORGANS.
DESTROY STRUCTURES
Treatment REMOVAL WILLALLEVIATE REMOVAL WILL NOT
RESTORE THE FUNCTION.

61. Principal Pathways of Malignancy
PATHWAYS OF
MALIGNANCY
1)PROLIFERATION
2) CELL CYCLE
PROGRESSION
3) DNA REPAIR
4) APOPTOSIS,
5)ANGIOGENESIS
6) METASTASIS
AND INVASION

62. Tumour genesis (oncogenesis, carcinogenesis) is a multistep process and
that these steps reflect genetic alterations that drive the progressive
transformation of normal human cells into highly malignant derivatives
(cancer).
Steps of carcinogenesis:
1. Initiation
2. Promotion
3. Progression
4. Malignant conversion

63. Cancer
Carcinoma- This type of cancer originates
from the epithelial layer of cells that form the
lining of external parts of the body or the
internal linings of organs within the body.
Sarcoma-These
cancers originate in
connective and
supportive tissues
including muscles,
bones, cartilage and
fat.
Myeloma - These
originate in the
plasma cells of bone
marrow.
Leukaemia – This is a group of cancers that
are grouped within blood cancers.
Lymphoma -
These are
cancers of the
lymphatic
system.
Mixed type - These have two or
more components of the cancer.

64. Cancer Classification
 Classification by site of origin.
 Classification by tissue types.
 Classification by grade.
 Classification by stage.

65. REFERENCES
1. Iwasa.Jennet, Marshall. Wallace, Karp.Gerald, “ Cell Biology ” ,
Seventh edition, International Student edition, Wiley Publications,
Page No.345-349, 624-663.
2. Vyas.S.P., Mehta.A, “Cell and Molecular Biology” CBS Publishers
and distributors, Second Revised edition 2010, Page No. 220-229.
3. Choi.Eunhee, kikuchi.Sotaro, Yu. Hongtao, “Mitotic regulators and
MAPK PATHWAY” Article No.1473(2019), Nature.com. Page
No.1-29.
4. Villarino.Alejandro, Kanno.Yuka, “Mechanisms and consequences
of JAK-STAT signalling in the immune system” Article No. 374-
384(2017), Nature Immunology18.
5. Schieber.M, Chandel.Navdeep, “ROS function in redox cell
signalling and oxidative stress” Ncbi.nlm.nih.gov, Page1-32.

66. Thank You……..