Overview of cancer
Point to be covered1. Overview of cancer
2. Types and reason of cancer
3. Basic idea about progression of tumor
4. Cell division
5. Cell division regulation
6. Genetic instability
7. Mutation
8. Invasion
9. Angiogenesis
10. Metastasis
11. Grading and staging
12. Treatment
Cancer
• Cancer is a large group of diseases characterized by uncontrolled growth and spread of abnormal cells
• Cancer cells:– Lose control over growth and multiplication
– Do not self-destruct when they become worn out or damaged
– Crowd out healthy cells
Cancer• Cancer cells reproduce every 2-6
weeks
• Size of cancer cells:
One million cancer cells = head of a pin
One billion cancer cells = a small grape
• Five-year survival rate (starting from the time of diagnosis)
2-6 weeks
2-6 weeks
2-6 weeks
Carcinogens• Ionising radiation – X Rays, UV light
• Chemicals – tar from cigarettes
• Virus infection – papilloma virus can be responsible for cervical cancer.
• Hereditary predisposition – Some families are more susceptible to getting certain cancers. Remember you can’t inherit cancer its just that you maybe more susceptible to getting it.
LifestyleLifestyle
EnvironmentEnvironment
Family Family HistoryHistory
Types Cancers
– Carcinoma: epithelial cells
– Adenocarcinoma: glandular tissue
– Sarcoma: connective tissue
– Lymphoma: lymph tissue
– Leukemia: blood forming tissue (marrow)
– Gliomas: cancer of brain glial cells
Carcinomas (cells that cover internal and external body surfaces)
Lung
Breast
ColonColon
BladderBladderProstate Prostate (Men)(Men)
LeukemiaLeukemia(Blood Cells)(Blood Cells)
LymphomasLymphomas(Lymph nodes)(Lymph nodes)
SarcomasSarcomasCells in supportive tissues – bones & muscles
Proliferation and differentiation
• Increase in the cell number with exact passages of genetic information to their daughter cells
• Different kinds of cells with the specialized morphology, metabolism and physiological functions from the cells of the same origin.
Tumor invasion of the basement membrane• Benign lesion characterized by the continuous
basement membrane, that separate neoplastic epithelium from the stroma
• Malignant tumor have loss of basement membrane around tumor cell in stromal compartment
Normal cell
Inactivation of tumor suppressor gene
DNA damage
Activation of proto-oncogene
Unregulated proliferation Decreased apoptosis
Mutation in somatic cells
Alteration of apoptosis gene
Failure of DNA Repair
Tumor progression
Malignant neoplasm
Clonal expansion
Invasion Metastasis
Acquired DNA damaging agent
i.e. chemical, radiation, virus mutation i.e. genes
affecting DNA repair and apoptosis
pathway
Successful DNA repair
•Angiogenesis•Escape from immunity Additional mutation
Phases of the cell cycleCell cycle have two phase
(1) S phase (Non-division phase)
(2) Division phase (Division phase)
Gap phase
•G1 devoted for metabolic activity for cell growth and preparation for DNA replication
•G2 preparation for mitotic cell division takes place
Check Point
Check Point
Checks DNA damageBefore final commitment for replication:
defect can be repaired as chromatids are still together
G1 arrest
Checks integrity of DNA Check completion of DNA replication.
Are they ready for mitosisG2 arrest
Cell Cycle check points
Control of the Cell Cycle
• Cdks (Cyclin-dependent kinases)
• Cyclins
• CKIs(Cyclin dependent kinase inhibitor )
The passage of a cell through the cell cycle is controlled by proteins in the cytoplasm. These protein are:
CDK ( Cyclin dependent kinase) &Cyclins • CDK contain two parts, an enzyme
(kinase) and a modifying protein (Cyclin)
• Kinases are regulatory enzymes that catalyze the addition of phosphate groups to protein substrates
• Cyclins synthesize and degenerate at each cycle, work as docking site for substrate
• Cdk4 and Cdk6 regulate entry into cell cycle
• Cdk1 and Cdk2 operate primarily in M phase and S phase
CDK ( Cyclin dependent kinase) &Cyclins • CDKI have capability of sensing problems
• Kip family: P21waf1/cip1, P27kip1 ,P57kip2
• Ink4 family: P16Ink4a,P15Ink4b,P18Ink4c,P19Ink4d
• INK4 proteins binds to CDK 4 & 6
• Cip –Kip proteins binds to CDK 1 & 2
Cyclins and CDKs
Kinasecomplex
Vertebrate Yeast
Cyclin CDK Cyclin CDK
G1-CDK Cyclin D* CDK4 、 6 Cln 3 CDK1(CDC28)
G1/S-CDK Cyclin E CDK2 Cln 1、2
CDK1(CDC28)
S-CDK Cyclin A CDK2 Clb 5、6
CDK1(CDC28)
M-CDK Cyclin B CDK1(CDC2)
Clb 1-4 CDK1(CDC28)
Tumor as result
• Overexpression of cyclins
• Overexpression of Cdks
• Deactivation of CkIs
• Abnormity of checkpoints
Normal cell
Inactivation of tumor suppressor gene
DNA damage
Activation of proto-oncogene
Unregulated proliferation Decreased apoptosis
Mutation in somatic cells
Alteration of apoptosis gene
Failure of DNA Repair
Tumor progression
Malignant neoplasm
Clonal expansion
Invasion Metastasis
Acquired DNA damaging agent
i.e. chemical, radiation, virus mutation i.e. genes
affecting DNA repair and apoptosis
pathway
Successful DNA repair
•Angiogenesis•Escape from immunity Additional mutation
Signs for Genomic Changes in Cancer• Changes in chromosome numbers
• Aneuploidy
• Chromosomal changes- Increase in DNA copy number - Loss in chromosome
• Hypermethylation at promoter region is a common mechanism by which tumor suppressor loci are epigenetically silenced in cancer cells (aberrant gene transcription)
LOH (Loss of heterozygosity)
Rb RbRb
Second hitInherited Rb
A
b
a
B
A
b
Pre-tumor cellTumor cell
• LOH termed as pre-tumor cells are heterozygous for tumor suppressor gene, alleles of genetic marker surround the gene
•Tumor cell will loss the normal tumor suppressor allele & surrounding markers too
Telomere and telomerase•TelomerTelomer 6 nucleotide sequence at end of chromosome to avoid the chromosomal end to end fusion
•Telomerase (RNA containing enzyme) Facilitate replication of telomer
•Mitotic clockNormally telomer loss at each cell division, serve as cellular mitotic clock to limit no. of cell division and cellular life span
•Cellular crisisIn extended cell division, loss of capping resulting into chromosomal instability which leads to loss of cell viability and proliferation capacity
Telomerase activity is detected in 80% to 90% most common cancer
What are the genes responsible for tumorigeniccell growth?Normal
Cancer
Proto-oncogenes Cell growthand
proliferationTumor suppressor genes
+
-Mutated or “activated”
oncogenes Malignanttransformation
Loss or mutation ofTumor suppressor genes
++
Mutation leads to Oncogene
Each proto-oncogene is composed of 2 region: • Structural region (SR) encodes AA• Regulatory region (RR) modulate expression as per stimuli
Change in either SR or RR create active onco-gene
Regulatory region leads to inappropriate level of growth inducing protein
Structural mutation leads change in structure & function of protein
Proto-oncogene
oncogene
Ras is GTP binding protein act as digital switch
Ras regulate cell growth – Play a role in mitogenesis by 2
mechanism
• Nucleotide exchange (GDP by GTP)
• GTP hydrolysis ( convert active Ras to inactive Ras)
Mutated Ras:
Trapped in permanently active state due to loss of GTP hydrolysis through GAP binding
• Leads to continuous activation of MAP kinase signaling
p53 maintain integrity of Genome• P53 mutation is common in >50% human cancer
• Normal p53 maintain the genomic integrity via• Response to DNA damage (cell cycle arrest) via P21 CDK
inhibitor
• Inducing apoptosis
• Disruption/deletion of p53 gene • Uncorrected DNA damage• Uncontrolled cell proliferation via decreased apoptosis
Loss of normal Apoptosis pathway
• Inactivation of p53, leads increase in BCl-2: causes enhanced cell survival and genetic instability and clonal suspension and diversification of tumor without activation of death pathway
Normal cell
Inactivation of tumor suppressor gene
DNA damage
Activation of proto-oncogene
Unregulated proliferation Decreased apoptosis
Mutation in somatic cells
Alteration of apoptosis gene
Failure of DNA Repair
Tumor progression
Malignant neoplasm
Clonal expansion
Invasion Metastasis
Acquired DNA damaging agent
i.e. chemical, radiation, virus mutation i.e. genes
affecting DNA repair and apoptosis
pathway
Successful DNA repair
•Angiogenesis•Escape from immunity Additional mutation
Invasion and Metastasis
• Abnormal cells proliferate and spread (metastasize) to other parts of the body
• Invasion - direct migration and penetration into neighboring tissues
• Metastasis - cancer cells penetrate into lymphatic system and blood vessels
Cell migration via cell –cell intraction
•Majority of cancer occur in epithelial cells, normally maintenance of cell- cell contact maintained by (TJ & AJ) Junction, which maintains by cadherin
•Any disruption to cadherin to catenin results in loss of cell adhesion(Cadherin, integrins, Immunoglobulin and CD-44)
•E-cadherin also considered as metastatic suppressor
Cell- ECM (Extra cellular matrix) interaction
ECM provides not only scaffolding for the cellular constituents & also initiates tissue morphogenesis, differentiation and homeostasis
The ECM is composed of two main classesMacromolecules: ProteoglycansFibrous proteins i.e collagens, elastins, fibronectins and laminins
Cell –ECM interaction mediated by integrins receptor present on tumor cell
Loss of cadherin •Reduces the cells to adhere each other •Facilitate cell detachment from tumor•Advancing into surrounding tissue
Attached to the ECM component•Laminin of ECM bind to integrins of tumor• Activate the protease of tumor cell (MMPs)•MMPs degrades the iv collagen and release
VEGF as angiogenic stimuli
•MMP release activate the GF (PDGF, TGF) of ECM affect the growth of tumor•Degradation of ECM creates the passage of invasion & signal for angiogenesis
Tumor progression
Angiogenesis is a normal and necessary process
Angiogenesis is pivotal in:-
•Tissue growth and development
•Plays role in normal physiology
•Wound healing,
•Female reproductive cycle
•Inflammation and embryogenesis
Function of Angiogenic factors
Recruitment of pericytes and smooth muscle cell
Blood vessel formation
FGF
Tie 2Blood vessel Stablization
and remodeling
Artery , vein differentiation, vessel remodeling
Epherins
Angiogenesis controls tumor growth.
• Tumor can stay in a ‘dormant’ state for long periods.
• The angiogenic switch allows for growth of the tumor to occur.
• Increased angiogenesis correlates with worse prognosis.
Angiogenic Switch dynamic balance of pro & anti-angiogenic factor tripped in favor of blood vessel formation
Link b/w Inflammation & Malignancy
Chronic inflammation leads to cancer
• H. Pylori Stomach cancer
• Chronic reflux esophagitis Barrett syndrome
• Chronic pancreatitis Ca Pancreas
• Ulcerative colitis Colon cancer
• HCV, HBV Liver cancer (HCC)
The most common cancer arise in the skin, prostate, breast, lung and colon
• More than 100 kinds of cancer• Most common type is skin cancer• Liver cancer• Stomach cancer• Prostate cancer• Colon, breast, and lung
Grading and staging
• Grade: GX: Grade cannot be assessed
(Undetermined grade)
G1 Well-differentiated (Low grade)
G2 Moderately differentiated (Intermediate grade)
G3 Poorly differentiated (High grade)
G4 Undifferentiated (High grade)
• Staging systems (various): carcinoma
– Stage 1: confined to organ– Stage 2: locally invasive– Stage 3: lymph node invasion– Stage 4: spread to distant sites
Extent of the prim. tumor and extent of spread in the body
Helps planning treatment and Prognosis
TNM - system
• Most common (accepted by UICC, AICC)
• Based on : T extent of the tumor
N extent of spread to the lymph nodes
M presence of metastasis
• Number indicates size or extent of the prim. tumor and the extent of spread of metastasis
Cancer Treatment and Prevention
When a person is diagnosed with cancer, a variety of weapons are available to combat it
1-local therapy:• Surgery.• Radiation therapy
2-systemic treatment:• chemotherapy.• Hormonal therapy• Monoclonal antibodies• Radioactive material
Detection method of Cancer
• Amplification Technique
• Sequencing
• Microarray
• Protein array
• Tissue microarray Visualization
• Tissue microarray analysis