Molecular and cellular
biology of cancer
Mgr. Lucia Knopfová, PhD.
Prof. RNDr. Jana Šmardová, CSc.
Institute of Experimental Biology
Faculty of Science
MU Brno
Bi9910en
1.  Introduction
terminology, historical background,
classification of tumors,
oncoviruses
Molecular and cellular
biology of cancer
Course organization
•  Course ending: EXAM
–  Written part: obligatory; 25 open questions, max. 50 points, min.
30 points
–  Oral part
Supplemetary literature I
Ø Robert Allan Weinberg: „The Biology
of Cancer“ (GS Garland Science,
2014; 2007)
Additional textbooks of cancer
biology
Ø  Lauren Pecorino: „Molecular Biology of Cancer.
Mechanisms, Targets, and Therapeutics“ Oxford
University Press 2012, ISBN 978-0-19-957717-0
Ø  Robin Hesketh: „Introduction to Cancer Biology“
Cambridge University Press 2013, ISBN
978-1-107-60148-2
Supplementary literature II
•  Hanahan D. and Weinberg R.A.: Hallmarks of
Cancer. Cell (2000) 100: 57-70.
•  Hanahan D. and Weinberg R.A.: Hallmarks of
Cancer: The Next Generation. Cell (2011) 144:
646-674.
•  Weinberg R.A.: Coming full circle – from endless
complexity to simplicity and back again. Cell
(2014) 157: 267-271.
„Supplemetary literature III“
Ø  Robert Allan Weinberg: One renegade
cell: How cancer begins. Science
Master Series, 1998
Ø  Siddhartha Mukherjee: The
Emperor of all Maladies. A
Biography of Cancer.
Scribner 2010
History: outline
•  400 BC Hippocrates desribed cancer as long finger-like
extensions (resembling crab legs) protruding into healthy
tissues:
- Greek:
karkinos (καρκίνος) = crab; onkos (ὄγκος) = mass, volume
- Latin: cancer = crab
History: outline
•  Descriptive (epidemiologic) data:
–  1775 –scrotal skin cancer in chimney sweeps (associated
with exposure to soot and poor hygiene conditions)
–  1842 – higher breast cancer mortality in nuns (association
with nulliparity and absence breast feeding)
–  1902 – radiation-induced skin cancer
Ø carcinogen – mutagen
–  beginning of 20th century – familial aggregation of cancer
History: outline
•  1909 – Francis Peyton Rous – cancer transmitted by infectious
substance in hen
study of tumor-inducing viruses (oncogene - a fragment of viral
genome causing a tumor) (1966 – Nobel prize; first nominated in
1926)
Weinberg RA. The Biology of Cancer. Garland Science 2007
History: a landmark
in 1971
•  1971 – president Nixon announced „War on Cancer“, supported
by a huge subventions by US goverment, prevailing conviction
that cancers are caused by viruses (research focus on DNA-
oncoviruses)
•  1976 – Bishop, Varmus – discovery of c-src (protooncogenes):
linked with mitogenic signal pathway
investigations of acutely transforming viruses lead to the
identification of more than 30 different oncogenes
•  Non-acute transforming viruses (insertion mutagenesis): 25
different proto-oncogenes discovered
•  1982 –identification of ras oncogene lead to the discovery that voncogene
and protooncogene may differ in only one nucleotid!
•  Human cancers caused by retroviruses were not found
•  (but later the knowledge of retroviruses enabled fast discovery of
the cause of AIDS)
•  1969 - Henry Harris (cell fusion) – tumor suppressors –
recessive genes- brakes)
•  1971 – Alfred Knudson – retinoblastoma – „two hits hypothesis“
•  1989 – Bert Vogelstein – distinct mutations in specific genes
(oncogenes and tumor suppressors) are connected with discrete
stages of the progression of colorectal carcinoma
•  DNA tranfer (transformation, transfection)…
History: outline
History: outline
•  biochemistry: study of oncoproteins, their localizations,
interactions
•  molecular biology: isolation, characterization and targeted
expression of eukaryotic genes
•  cellular biology: molecular mechanisms regulating cell growth
and division
•  genetics of somatic cells and viruses: functional tests of specific
genes
•  …
History: outline
•  biochemistry: study of oncoproteins, their localizations,
interactions
•  molecular biology: isolation, characterization and targeted
expression of eukaryotic genes
•  cellular biology: molekular mechanisms regulating cell growth
and division
•  genetics of somatic cells and viruses: functional tests of specific
genes
•  …
p21: WAF1 - „wild type p53-activated fragment“
cip1 - „Cdk-interacting protein 1“
sdi1 - „senescent cell-derived inhibitor 1“
History: outline
•  biochemistry: study of oncoproteins, their localizations,
interactions
•  molecular biology: isolation, characterization and targeted
expression of eukaryotic genes
•  cellular biology: molekular mechanisms regulating cell growth
and division
•  genetics of somatic cells and viruses: functional tests of specific
genes
•  …
p21: WAF1 - „wild type p53-activated fragment“
cip1 - „Cdk-interacting protein 1“
sdi1 - „senescent cell-derived inhibitor 1“
gene: CDKN1A (6p21.2)
History: outline
•  biochemistry: study of oncoproteins, their localizations,
interactions
•  molecular biology: isolation, characterization and targeted
expression of eukaryotic genes
•  cellular biology: molekular mechanisms regulating cell growth
and division
•  genetics of somatic cells and viruses: functional tests of specific
genes
•  epigenetics
p21: WAF1 - „wild type p53-activated fragment“
cip1 - „Cdk-interacting protein 1“
sdi1 - „senescent cell-derived inhibitor 1“
gen: CDKN1A (6p21.2)
History: outline
•  „Omics“ era: genomics, transcriptomics, proteomics,
epigenomics, kinomics, metylomics, glycomics, metabolomics…
Ø  …Robert Allan Weinberg: Coming full circle – from endless
complexity to simplicity and back again. Cell (2014) 157:
267-271.
History: outline
•  1971: president Nixon declared „War on Cancer“…
•  2012: World Oncology Forum, Lugano, Switzerland
•  Hanahan D. The cancer wars 2. Rethinking the war on cancer.
Lancet 2014, 383: 558-563
Ø  We won battles NOT war
Ø  New strategy needed: „overarching and holistic battlespace war
plan against cancer“
1.  Attack all (more) hallmarks of cancer cells
2.  Attack not only cancer cells, but also their „supporters“
3.  Consider „geographic“ aspect of the conflict (primary tumor vs
metastases)
History: outline II
Greaves M. Nat Rev Cancer. 16: 163-172, 2016
Ø  Landmarks in leukemia research, that pave the way
for biological and clinical discoveries in oncology
Tumor, neoplasm
- new and abnormal tissue in multicellular organism that does not
have a physiological function in this organism and its growth not
controlled
- genetically conferred abnormal gain of tissue mass that has
clonal character and its growth is not coordinated with the growth
of the surounding tissues and with homeostasis
Terminology
Classification of tumors I:
according to the capacity to invade surrounging
tissues
•  benign: stay in their primary location without invading
other sites of the body. They do not spread to local
structures or to distant parts of the body.
•  malignant (cancerous): invade surrounding tissues,
spread to distant sites via the bloodstream or the
lymphatic system, give rise to the secondary tumors
(metastases) at other parts of the body
•  According to the spatiotemporal occurence we distigush
primary and secondary tumors
(! secondary – (i) therapy-related; (ii) metastases
lethal may be also non-metastatic tumor)
Cancer
Terminology
-  a disease caused by an uncontrolled division of cells in a part
of the body that spread to other parts of the body
Normal → malignant tissue
precancerous changes
•  hyperplasia - increased cell production, but cells are
phenotypically normal
•  dysplasia – the presence of abnormal cells within a tissue or
organ, cytological changes including cell size, shape, nucleo/
cytoplasmic ratio, altered mitotic activity; and abnormal frequency
of cell types
•  metaplasia – transient changes of cell phenotype caused by
external signals; the replacement of a mature, differentiated cell
type by another cell type that does not typically occur in the tissue
in which it is found, often at boundary of two types of epithelial
tissues: esophagus – stomach – e.g Barrett esophagus
Barrett esophagus
•  The condition of the intestinal metaplasia in esophagus as a result of
gastroesophageal reflux disease (GERD, stomach acid flowing backwards into
the esophagus). The nonkeratinized squamous epithelium that typically covers
the esophagus is not resistant to the acidic stomach fluids. It becomes
inflammed and eventually if the irritation persists, squamous epithelium
transforms into nonciliated columnar epithelial cells that is more acid-proof.
•  Barrett esophagus can be reversed by treating the underlying GERD; however,
if the condition persists, esophageal cells can become dysplastic, which can
eventually lead to cancer.
•  It belongs among „precancerous conditions“, it increases the risk of esophageal
cancer 30x
•  It could be manifested only by heartburn
•  polyps, papilomas, warts – structures visible by eye, contain
same cell types as normal tissue, but exhibit expansive growth and
create macroscopic mass, dysplastic, do not penetrate basement
membrane, benign
•  invading tumors – penetrate basement lamina of epithelial
tissues, malignant
•  metastatic tumors – also malignant, form secondary foci, not
only invading but able to survive in circulation and adapt to the new
conditions at the distant site
Normal → malignant tissue
•  carcinomas – tumors of epithelial tissues (around
80-90% human tumors)
•  sarcomas – solid tumors of connective tissues –
muscles, bones, cartilage
•  leukemias a lymphomas – derived from
haematopoietic and immune cells
•  neuroectodermal tumors – derived from neural tissue
•  germinal tumors – derived from totipotent germ cell
•  mixed tumors
Classification of tumors II:
according to the cells/tissues they arise from
Solid tumors - create a single mass or many masses, that
grow in organ systems and can occur anywhere in the
body (carcinomas, sarcomas, neuroectoderm tumors, etc)
Liquid tumors (blood cancer) - circulate throughout the
body via the bloodstream, develop in the blood, bone
marrow, or lymph nodes (leukemias, lymphomas,
myelomas)
Classification of tumors II:
according to the cells/tissues they arise from
Carcinomas
Derived from z epithelial
cells:
Epithelial (Ep) layer form
inner lining of body cavities
and outer surface of body.
The basement membrane
(BM) sits
between epithelium and
the underlying connective
tissue that containes
stromal cells and collagen
fibres (C).
Weinberg RA: The Biology of Cancer. GS, 2007
Carcinomas
Ø  80-90 % of tumors
•  Spinocellular / squamous cell carcinomas – originate in cells
that form protective layers (the surface of the skin, the lining of
the hollow organs of the body, and the lining of the respiratory
and digestive tracts)
•  adenocarcinomas – derived from glandular epithelium with
exocrine function which lines certain internal organs and makes
and releases substances in the body, such as mucus and other
fluids
•  mixed – coexistence of both types
Sarcomas
Ø  1% of tumors
Ø  Tumors of connective tissues arising from mesenchymal or
ectodermal tissues:
•  fibrosarcomas – derived from fibroblasts, cells producing
collagen and extracellular matrix
•  liposarcomas – from adipocytes, cells that store lipids in the
cytoplasm
•  osteosarcomas – from osteoblasts, cells that produce bone
matrix
•  leiomyosarcomas a rhabdomyosarcomas - from myocytes
(muscle cells)
•  angiosarcomas – from precursors of endothelial cells
Leukemias a lymphomas
Ø  Tumors derived from haematopoetic and immune cells
•  leukemias – from circulating or bone marrow cells
•  lymphomas – from B and T lymphocytes, form clusters (solid
tumors), often in lymph nodes
Neuroectodermal tumors
Ø  Tumors derived from various cells of central and periferal
nervous system
•  gliomas
•  glioblastomas
•  neuroblastomas
•  schwannomas
•  meduloblastomas
Ø  Around 1.3% of diagnosed tumors, but represent cca 2.5% of
cancer-associated deaths
Other tumors
Ø  some tumors do not belong to any of the classes:
•  melanomas – derived from melanocytes, cells producing
melanin (pigment), neural crest-derived cells located in the
bottom layer of the skin's epidermis
•  small cell lung carcinomas– lung cells that display
neuroendocrine markers
§  transdifferentiation – switch/transformation of the cell type,
acqusition of new differentiation markers
§  dedifferentiation – not possible to track the type of the tissue
that gave rise to the tumor: anaplastic tumors (1 to 2 % of
tumors)
Classification of tumors III:
according to the location in the body
where the cancer first developed.
•  lung carcinoma
•  colorectal carcinomas
•  breast carcinoma
•  acute myeloid leukemia
•  acute lymphocytic leukemia
•  etc.
Intermezzo: Classification of solid
tumors in clinical praxis
For every oncological patient pathologist asses:
•  typing/grading
•  staging
•  rating
„Typing“
The International Classification of Diseases for Oncology (ICD-O-3) is
designed to categorize tumors:
Unique numerical code used for coding the site (topography) and the histology
(morphology) of the neoplasm
Structure of topography (site) code:
Structure of morphology code:
•  4 digits cell type (histology)	
•  1 digit behavior	
•  1 digit grade, differentiation or phenotype	
„Typing“
The International Classification of Diseases for Oncology (ICD-O-3) is
designed to categorize tumors:
Morphology code:
First number after slash denotes biological properties (behaviour):
0: benign
1: uncertain behaviour
2: carcinoma in situ
3: malignant, primary site
6: malignant, metastasis
9: malignant, uncertain whether primary or metastasis
Example: code 8850/0 stands for lipoma
code 8850/3 stands for liposarcoma
„Typing“
Morphology code:
Second number after slash denotes differentiation (grading) – only for
malignant tumors!
Example of complete code:
Differentiation describes
how much a tumor
resembles the normal
tissue from which it arose.
„Staging“
Refers to the anatomical extent of the cancer:
-  the size of the tumor
-  whether the tumor crossed specific anatomical barriers
- whether the cancer has spread to nearby lymph nodes
- whether the cancer has spread to a different part of the body
TNM staging system:
“T” category describes the
primary tumour site and size:
Tx: tumor cannot be assessed
Tis: carcinoma in situ
T0: no evidence of tumor
T1, T2, T3, T4: size and/or extension
of the primary tumor
mucosa
lamina propria
inner muscle layer
outer muscle layer
example: bladder carcinoma
„Staging“
TNM staging system:
…
“N” category describes the regional lymph node involvement
Nx: lymph nodes cannot be assessed
N0: no regional lymph nodes metastasis
N1, N2, N3: regional lymph node metastasis present
“M” category describes the presence or otherwise of
distant metastatic spread
M0: no distant metastasis
M1: metastasis to distant organs (beyond regional lymph nodes)
Example: T3N1M0
„Rating“
Molecular classification – presence/absence of specific molecules
•  Some of them are diagnostic (e.g. specific chromosomal
translocation in lymphomas and some sarcomas)
•  Some are prognostic and determine the choice of therapy (e.g.
–N-MYC amplification in neuroblastoma, hormone receptors
(ER, PrR in breast carcinoma).
•  Others are targeted by specific anti-cancer drugs thereby
predict response to the therapy (např. HER2/Neu for Herceptin,
Rituximab, Glivec,..).
Cancerogenesis
Ø  Process of the development and progression of tumor
•  multistep
•  Based on gradual accumulation of genetic and
epigenetic changes
alias: tumorigenesis, carcinogenesis
(Neoplastic) transformation
Ø  Transformation of somatic cell into a cancer cell
Cancerogenesis is driven by
gradual accumulation of
(epi)genetic changes
Koptíková Jana, 2016
Multistep cancerogenesis
accompanied by sequence of clonal
expansions
Weinberg RA. The Biology of Cancer. Garland Science 2007
Clonal model of cancerogenesis:
selection, clonal expansion
normal
cells
Competing subclones malignant clone
YEARS
Are tumor monoclonal or
polyclonal?
Weinberg RA. The Biology of Cancer. Garland Science 2007
Tumor is complex tissue
Tumor contains not only transformed cancer cells (a), but also other
host cells that together with extracellular components form tumor
microenvironment (b).
cancerogenesis vs. neoplastic transformation
Cellular composition of solid
tumor
1. Tumor parenchyma
transformed malignant cells
2. Tumor stroma
•  resident and non-resident cell types: endothelial
cells, pericytes, fibroblasts, lymphocytes,
macrophages
•  for mechanical and nutritional support
•  Transport function (signal tranduction,
chemoattactants, storage of growth factors)
•  crucial for angiongenesis and metastasis
How many and what genes are
altered during cancerogenesis?
•  If one alteration was enough for
tumor development, probability
of the disease would be ageindependent
– there would be
linear relationship
•  But the disease risk markedly
increases with age. Curve of
the relationship reflects a
complex process when several
independent events occur
sequentially.
Weinberg A.R.: One renegade cell.
Carl O. Nordling
Ø  1953: it was first speculated that neoplastic transformation does
not occur in a single step
Ø  An architect Carl O. Nordling studied deaths frekvencies for
cancer patients of different age (from 25 to 74 years) and found
the death rate increased proportionally with the sixth power of
the age.
Ø  he deduced that a cancer cell was the end-result of at least six
successive mutations
Nordling CO. A new theory on cancer–inducing mechanism. Br.J.Cancer 7: 93-112, 1953
Carl O. Nordling
Nordling CO. A new theory on cancer–inducing mechanism. Br.J.Cancer 7: 93-112, 1953
Carl O. Nordling
Nordling CO. A new theory on cancer–inducing mechanism. Br.J.Cancer 7: 93-112, 1953
Nordling CO. A new theory on cancer–inducing mechanism. Br.J.Cancer 7: 93-112, 1953
Carl O. Nordling
•  What is this cell??
GIT vs. GIST
vs. lymfomas…
First „renegade“ cell
Stem cell??
Progenitor cell??
Differentiated cell??
First „renegade“ cell
•  What is this cell?? !
Stem cells
Ø  Self-renewal capacity and production of cells undergoing
differentiation
Ø  Relatively rare
Ø  Quiescent
Ø  Resistant to toxins and chemicals
Ø  Intense DNA repair
Cancer stem cells
Ø  Both normal and tumor tissues are hiearchically organized; include
subpopulation of stem cells
Ø  Cancer stem cells (CSCs):
•  Have potential to form new heterogeneic tumor, when implated in a
suitable host
•  Portion of CSCs in tumor tissue associates with prognosis
Ø  There are two models explaining presence of CSCs
Chaffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015
Cancer stem cells: model A
Ø  CSCs result from transformation of normal stem cells
Chaffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015
Cancer stem cells: model A
Against:
1. low probability that rare, random and advantageous mutations occur
in such a small target population
2. mutations occur more frequently in highly proliferating cells (the
growth rate of the population of epithelial SC is much slower than their
progeny – progenitor cells that have high mitotic activity and grow
exponentially)
3. clonal expansion depends on advantageous phenotype;
undifferentiated SCs are less likely to develop such phenotype
Chaffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015
Cancer stem cells: model A
Ø  Model according to which a founder cell of carcinomas is
normal epithelial SC is matematically and biologically
improbable
Chaffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015
Cancer stem cells: model B
Ø  Transforming genetic (and epigenetic) changes occur in
progenitor cells that dedifferentiate into SCs (CSCs).
Chaffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015
Cancer stem cell: „model A/B“
Ø  Transforming mutations in different founder („renegade“) cells may result in
the same type of tumor (convergence) ⇒ some driving mutations are so
strong in determing the fate of the cell that they override transcriptional
context and origin of cells
Chffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015Lytle NK et al: Stem cell fate in cancer growth, progression and therapy resistance. Nat Rev Cancer. 18: 669-680, 2018
Cancer stem cells:
„model A/B“
Ø  Transforming mutations may lead to the different types of tumors
(divergence) depending on the identity of the founder cell, i.e. on the
transcriptional and epigentical profile
Chffer CL a Weinberg RA: How does multistep tumorigenesis really proceed? Cancer Discov. 5(1): 22-24, 2015Lytle NK et al: Stem cell fate in cancer growth, progression and therapy resistance. Nat Rev Cancer. 18: 669-680, 2018
•  Cancer is not a monogenic disease
•  It is estimated that 4-7 events (hits) are required for
cancer development
•  There are hundreds of distinct genes that may be
altered during cancerogenesis
How many and what genes are
altered during cancerogenesis?
Cancer Genome Atlas consortium
•  Genome sequencing of tumors
•  2009: sequencing of the genomes of ovarian carcinomas,
pancreatic and lung cancer, melanomas, and some types of
leukemia finished
•  thereby the complete catalogue of mutations in these cancer
types was acquired
Mukherjee S: Vládkyně všech nemocí. Nakladatelství MU 2015
Wood LD et al. Science 318: 1108-1113, 2007
Cancer Genome Atlas consortium
•  In individual samples of breast and colon cancer 50 to 80 genes
were mutated, in pancreatic cancer 50 to 60 mutations were
found
•  Even in brain tumors that often develop in relatively young age
(thus lower number of mutations would be expected) were found
40 to 50 mutated genes
•  In one sample of breast carcinoma of 43y old patient 127 genes
were mutated
•  There are just few cancer types that are exceptions to this rule
and carry only few mutations; e.g. Acute lymphoblastic leukemia
(ALL) has only 5 to 10 mutated genes
Mukherjee S: Vládkyně všech nemocí. Nakladatelství MU 2015
Wood LD et al. Science 318: 1108-1113, 2007
Cancer Genome
Atlas
consortium
Vogelstein B et al. Science 339: 1546–1558 ,
2013
•  In one type of tumor there is almost „depressing“ mutation
heterogeneity (B. Vogelstein)
•  Comparing two samples of breast tumors showed that set of
mutated genes is not the same
•  Genome sequencing confirmed hundreds of years of clinical
observations: cancer of each patient is unique, because every
cancer genome is unique
Cancer Genome Atlas consortium
Mukherjee S: Vládkyně všech nemocí. Nakladatelství MU 2015
Wood LD et al. Science 318: 1108-1113, 2007
Genomic landscapes of human
cancers
Bert Vogelstein: mutations in tumors are of two types:
•  (1) passenger (bystander, passive): during the course of
cancer divisions they accumulate mutations due to the DNA
replication errors, but they do not affect the biology of tumor,
they are just passively transfered during somatic cell division,
they do not have significance, just bystanders
•  (2) „driver“: i.e. directly stimulating growth and behaviour of
cancer cells, they determine biology of cancer cell
•  Passenger mutations occur accidentally, and their genomic
location is also accidental; on contrary driver mutations affect
key oncogenes and tumor suppressors, there is limited number
of such genes in genome
Wood LD et al. Science 318: 1108-1113, 2007
Vogelstein B et al. Science 339: 1546–1558 ,
2013
•  „passenger“ mutations occur accidentally
•  „driver“ mutations affect key oncogenes and tumor suppressor (e.g.
ras, myc a RB) are repeatedly found in samples; on „Vogelstein‘s
map“ they represent high mountains, whereas passenger mutations
form valleys
Genomic landscapes of human cancers
Mukherjee S: Vládkyně všech nemocí. Nakladatelství MU 2015
Wood LD et al. Science 318: 1108-1113, 2007
•  „mountains“ in cancer genomes–
i.e. the most frequently mutated
genes of a single cancer type, may
form distinct signaling pathways
(e.g. Ras-Mek-Erk)
•  How many pathways are usually
deregulated in cancer? Vogelstein
found that typically 11 to 15, in
average 13
Genomic landscapes of human cancers
Mukherjee S: Vládkyně všech nemocí. Nakladatelství MU 2015
Wood LD et al. Science 318: 1108-1113, 2007
•  Cancer is not a monogenic disease
•  It is estimated that 4-7 events (hits) are required for
cancer development
•  There are hundreds of distinct genes that may be
altered during cancerogenesis
How many and what genes are
altered during cancerogenesis?
There are hundreds of distinct genes
that may be altered during
cancerogenesis
•  Catalogue of Somatic Mutations in Cancer (COSMIC) Cancer
Gene Census (CGC)
•  version 86, August 2018: 719 „cancer-driving“ genes:
oncogenes + tumor suppressors (554 genes), fusion genes
Sondka Z et al. Nat Rev Cancer 18: 696-705, 2018; Tate JG et al. Nucl Acid Res 47: D941-D947, 2019
•  level 1 (554 genes): known function
and evident impact on
transformation
•  level 2: (i) less clear mechanism of
transformation; (ii) partner genes in
fusions with unknown function, yet
oncogenic function of respective
partner gene was confirmed
There are hundreds of distinct genes
that may be altered during
cancerogenesis
•  Catalogue of Somatic Mutations in Cancer (COSMIC) Cancer
Gene Census (CGC)
•  Version 95, November 2021: 733 „cancer-driving“ genes:
oncogenes + tumor suppressors, fusion genes
Sondka Z et al. Nat Rev Cancer 18: 696-705, 2018; Tate JG et al. Nucl Acid Res 47: D941-D947, 2019
https://cancer.sanger.ac.uk/cosmic
•  level 1 (579 genes): a documented activity relevant to
cancer, along with evidence of mutations in cancer
which change the activity of the gene product in a way
that promotes oncogenic transformation
•  level 2 (154 genes): genes with strong indications of a
role in cancer but with less extensive available
evidence
•  Cancer is not a monogenic disease
•  It is estimated that 4-7 events (hits) are required for
cancer development
•  There are hundreds (733) of distinct genes that may
be altered during cancerogenesis
•  In general there are 10 hallmarks of malignant cell
How many and what genes are
altered during cancerogenesis?
Six hallmarks of malignant tumor
Hanahan D and Weinberg RA. Cell 100: 57-70, 2000
Genomic instability is required for all necessary
mutations to accumulate.
6 hallmarks of cancer cells
Hanahan D. and Weinberg R.A., Cell 100 (2000) 57-70
10 hallmarks of malignant
tumor
Hanahan D. and Weinberg R.A., Cell 144 (2011)
646-674
10 hallmarks of cancer
Hanahan D. and Weinberg R.A., Cell 144 (2011)
646-674
Hanahan D., Cancer Discov (2022) 12 (1): 31–46.
14 hallmarks of cancer
Hanahan D., Cancer Discov (2022) 12 (1): 31–46.
14 Hallmarks of cancer
There are hundreds of genes that may
be altered during cancerogenesis
•  Catalogue of Somatic Mutations in Cancer (COSMIC) Cancer
Gene Census (CGC)
Sondka Z et al. Nat Rev Cancer 18: 696-705, 2018; Tate JG et al. Nucl Acid Res 47: D941-D947, 2019
Cancerogenesis has general
features ...
Hanahan D., Cancer Discov (2022) 12 (1): 31–46.
Cancerogenesis has individual
course
Individual is – sequence of hits
- number of hits
- actual mutated genes
Hanahan D and Weinberg RA. Cell 100: 57-70, 2000
Oncogenes
Protooncogene is a protein coding gene of eukaryotic cell
whose translational product participates in regulation
(stimulation) of cell division
Oncogene is altered (activated) protooncogene that
causes neoplastic transformation
Activation of protooncogene is a conversion of
protooncogene into oncogene
Mutations of protooncogenes are:
- activating
- dominant
- occur in somatic cells and only rarely in germ cells
Tumor suppressors
Proteins coded by tumor suppressor genes slow down
proliferation and keep cells in quiescent phase of cell
cycle. Their loss results in unregulated proliferation
Mutation of tumor suppressor gene are:
- inactivating
- recessive (connection with LOH, Loss of
heterozygosity)
- occur both in somatic and germ cells
14 Hallmarks of cancer ...
... multistep cancerogenesis – models:
Model of multistep
cancerogenesis
Development of colorectal carcinomas
Walther A et al. Nat Rev Cancer (2009) 9: 489–499
Oncogenic (cancer) viruses
•  Retroviruses (RNA viruses): have an oncogene in their genomes
(acutely transforming) or they activate eukaryotic protooncogene by
insertion mutagenesis (slowly transforming)
•  DNA cancer viruses: have different „strategy“ of transformation, they
code viral oncoproteins that interact with host tumor suppressors
(RB, p53, p300/CBP) and thereby promote transition of the cell cycle
to the S phase
Oncogenic (cancer) viruses
•  Retroviruses (RNA viruses): have an oncogene in their genomes
(acutely transforming) or they acitvate eukaryotic protooncogene by
insertion mutagenesis (slowly transforming)
•  DNA cancer viruses: have different „strategy“ of transformation, they
code viral oncoproteins that interact with host tumor suppressors
(RB, p53, p300/CBP) and thereby promote transition of the cell cycle
to the S phase:
SV40: large T antigen interacts with p53, RB, p300/CBP (via different
domains)
adenovirus: E1A interacts with RB and p300/CBP; E1B interacts
with p53
papillomavirus HPV-16, HPV-18: E6 interacts with p53, p300/CBP;
E7 interacts with RB
Some ways of p53 inactivation by viral
oncoproteins
Ø  Inactivation of tumor suppressor p53 is a crucial for
transformation by DNA viruses:
•  Large TAg (SV40) – interacts with DNA binding domain of p53 and
prevents binding of p53 to DNA
•  E1B (adenoviruses) – interacts with transactivating domain of p53
thereby hinders transactivation of its target genes
•  E4orf6 (adenoviruses) - causes degradation of p53
•  HBV X (hepatitis B virus) – blocks nuclear translocation of p53
•  E6 (papillomaviruses) – induced degradation of p53 (via cellular
E6AP ubiquitin ligase); E6 also directly inhibits transactivating
function of p53
Contribution of E6 and E7 proteins
to transformation by
papillomaviruses
viral oncoproteins: stimulate proliferation, inhibit apoptosis, increase
replicative potential, change morphology of cells, induce malignant
phenotype
Mantovani F a Banks L, Oncogene 20: 7874-7887, 2001
E6 - inactivates p53 (disrupted: blok G1, apoptosis, genetic
stability)
- interacts with p300/CBP (homeostasis pertrubation)
- activates expression of hTERT (telomerase activation)
- inactivates p16ink (distrubed cell cycle control)
- interacts with Bak (inhibition of apoptosis)
- interacts with E6BP/ERC-55 (inhibits differentiation)
- induces degradation of hDlg (and with other proteins
with PDZ motif) (change of morphology, induction of
motility)
E7 – binds protein RB
- inactivation of p21Cip and p27Kip (disconnected
proliferation and differentiation)
- prevent inhibitory effect of TGF-β on cell growth
- cause formation of multiple centrosomes
Mantovani F a Banks L, Oncogene 20: 7874-7887, 2001
Contribution of E6 and E7 proteins to
transformation by papillomaviruses
Clinical role of papillomaviruses
•  Identified more than 100 of different types of human
papillomaviruses (HPV)
•  fall into two groups: „high-risk“ and „low-risk“ types according to the
prognosis; „low-risk“ viruses cause no disease or benign tumors,
„high-risk“ viruses are functionally linked with malignant progression
•  cca 30 types of HPV preferetially infects anogenical areas, almost
all cervical tumors are associated with infection of „high-risk“ viruses
•  20% of tumors of oral cavity that are not linked with smoking history
or alcoholism are associated with HPV infection
2008: Nobel prize - Harald zur Hausen
Oncogenic viruses and human
cancer
DNA viruses:
•  Epstein Barr virus (EBV) – Burkitt‘s lymphoma (BL),
Hodgkin lymphoma (HD), other lymphomas, nasopharyngeal
carcinoma (NPC)
•  Hepatitis B virus (HBV) – hepatocellular carcinoma (HCC)
•  (Hepatitis C virus (HCV) – HCC a lymphomas; RNA virus!)
•  human papillomaviruses (HPV 16, 18,..) – anogenital
tumors, oropharyngeal tumors , warts
•  human herpesvirus type 8 (HHV8) - Kaposi sarcoma (KS)
•  Merkel cell polyomavirus (MCV) – Merkel cell carcinomas
(neuroendocrinne skin carcinoma)
Oncogenic viruses a human
cancer
RNA viruses:
In general: retroviruses do not cause many cancers, but research on
RNA cancer viruses helped to elucidate many aspects of
cancerogenesis
(1) acutely transforming, (2) slowly transforming and
(3) Human T-lymphotropic virus type 1 (HTLV-1) – causes adult T cell
leukemia/lymphoma (ATL)
•  HTLV-1 is transmitted primarily through infected bodily fluids including blood, breast
milk and semen
•  Most people with HTLV-1 infection are asymptomatic, but the lifetime risk of developing
adult T-cell leukaemia/lymphoma (ATL) among people with an HTLV-1 infection is
about 5%
•  Mechanism different from insertion mutagenesis: viral gene tax is responsible for
trancription activation of viral DNA and probably also activates transcription of host cell
genes: IL-2 and GM-CSF. Stimulation by these cytokines probably causes T-cell
neoplasia
•  (4) HIV-1 a HIV-2 – do not cause tumors directly, but via
immunosuppression
Infectious agents in
cancerogenesis
Ø  infectious agents are associated with 20 % of deaths
from cancer
•  6 % of worldwide mortality for liver cancer associated with
chronic hepatitis B and C (HBV, HCV)
•  5 % of worldwide mortality for cervical cancer associated with
HPV infection
•  9 % of worldwide mortality for stomach cancer associated with
persistent infection of Helicobacter pylori
Infectious agents in cancerogenesis
1. persistent infection that cause
inflammation and DNA damage,
2. initiation of oncogene expression,
3. immunosuppression activity of the host
Hatta et al. Biology (Basel). 2021 Jun 15;10(6):533
Helicobacter pylori
•  spiral, mikroaerofil, gramnegative bacteria
•  found in 1982
•  colonize stomach mucosa
•  Prevalence in our population is estimated around 30-55%;
increases with age
•  Discovery that chronic stomach
inflammation is caused by infection
by Helicobacter pylori: Barry
Marshall a Robin Warren – 2005 –
Nobel prize for physiology and
medicine
Conclusions of „Introduction“
Ø  Genes‘ functions are not limited to one cellular process
(cell cycle + apoptosis + genomic stability etc.)
Ø  Only small number of signaling pathways are
inactivated almost universally in tumors (RB, p53)
Ø  Single signaling pathway is ussually damaged in one
component only
Ø  Only a few genes affect only one exclusive cancer hallmark, most of
the genes involved in cancerogenesis affect multiple hallmarks
Ø  Different mutations of a single gene may have different impact of its
function
Ø  Classification of oncogenes and tumor suppressors is not clear-cut
Ø  Tissue specific impact
Ø  Dependent of the phase of tumor development
Sondka Z et al. Nat Rev Cancer 18: 696-705, 2018; Tate JG et al. Nucl Acid Res 47: D941-D947, 2019
(COSMIC)
Conclusions of „Introduction“
Thank you for your
attention!