EX2: Cancer Flashcards
Define neoplasm.
Abnormal mass of tissue produced when cells divide more than they should or do not die when they should.
what does a neoplasm lack
normal regulatory controls or cell growth and division
Define neoplasia.
Process of formation of an abnormal growth.
Define proliferation.
The process by which cells divide and reproduce.
when do cells proliferate
continuously or in response to body needs
What are the two ways by which cells proliferate?
Meiosis and Mitosis
What mediates cell proliferation?
Gene expression, growth factors, and signaling molecules.
What is the specific kinase that regulates cell division? when does it change?
mTOR, which also changes depending on local nutrition.
Define differentiation.
The process by which cells are transformed into different and more specialized cells.
What causes a cell to be differentiated? What influences this?
Gene expression, which is heavily influenced by growth factors and other stimuli (such as tissue environment)
what do we all start from
a single cell
As a cell becomes MORE specialized, is it more or less likely to undergo mitosis (divide)?
Less likely!
Important!!!!!!!!
what are stem cells
highly undifferentiated cells that have the potential to divide into multiple types of progenitor cells, which eventually become fully differentiated cells
Highly undifferentiated cells with SELF-RENEWAL
what do stem cells have the have the potential to do?
They have the potential to divide into multiple types of progenitor cells, which will eventually become fully differentiated cells.
What is a progenitor/parent cell? Why is it distinct from a stem cell?
It is still a cell that can divide, BUT parent cells has a limited range (or one type) of cell it can differentiate into.
What are the 5 types of stem cells from most undifferentiated to most differentiated?
Totipotent: give rise to ALL CELL TYPES - aka total range- including placenta
Pluripotent: give rise to all adult organism cell types (PLENTY)
Multipotent: give rise to MULTIPLE, but not all, cell types
Oligopotent: give rise to a FEW cell types (Oligo means few/scanty)
Unipotent: give rise to ONE cell type
What are most progenitor cells in terms of stem cell ranking?
Oligopotent or unipotent.
path of cellular differentiation
stem cell -> stem cell OR
-> progenitor cell ->daughter cell-> fully differentiated cell
Define carcinogenesis.
Origin and development of cancerous neoplasms
What kind of cells are most susceptible to neoplasia?
Rapidly dividing, labile cells
(carcinogenesis)
what kind of cells are less prone to neoplasia?
permanent, undividing cells
What percentage of genetic defects or mutations that lead to cancers develop post birth?
95%
Define oncogenesis.
The mechanism by which normal cells BECOME cancer cells.
What is monoclonal origin?
The concept of cancer originating from a single cell with genetic mutations.
mutations in what kind of genes can lead to cancer
genes that control cell growth and replication
What 3 genes are responsible for making sure our cells do NOT develop into cancer?
Mutator genes
Protooncogenes
Tumor suppressor genes.
so mutations in these genes can lead to cancer
Define mutator genes and give examples
They help repair mutated DNA and protect our genome.
The repair typically happens AFTER environmental insult
chemicals, radiation, viruses, inherited deficits
what is required for mutator genes to produce cancerous neoplasms
requires failure of MULTIPLE mutator genes to produce cancerous neoplasms
what happens from a failure of mutator genes to repair DNA
accumulation of other genetic mutations
Define protooncogenes.
Promote cell growth and development.
Specifically, they are normal genes that code for the proteins that regulate cell growth and differentiation, AND they have potential to become oncogenes through 3 methods
Define tumor suppressor gene.
regulate cell division and apoptosis to ensure the optimal number of cells
what does failure of the tumor suppressor gene mean
unrestricted growth and division of cell
two-hit hypothesis for failure
Does a single gene mutation usually cause cancer?
No!
What is RB gene
RB Gene (Rb protein) is the first tumor suppressor gene ever discovered.
Associated with retinoblastoma and other cancers.
what is TP53 gene
TP53 (p53 protein) is found on chromosome 17.
It is often implicated in many colon, lung, and breast cancers.
Regulates apoptosis of CANCER cells post chemo/radiation.
what is BCL2 gene-what cancer is it associated with
BCL2 gene (Bcl-2 protein) regulates apoptosis.
Mutation here results in a POORER response to cancer therapy.
Often associated with leukemia and other cancers.
What is the two-hit hypothesis?
Example: Retinoblastoma.
Even if a child carries the susceptibility gene for retinoblastoma, that is only 1 of the 2 chromosomes.
The susceptible child needs just 1 mutation to get retinoblastoma.
However, for someone not born with the gene, they need 2 individual mutations to get retinoblastoma, hence two-hit.
Note: See slide 19 for a visual.
what is point mutation
type of protooncogene turning to oncogene method
damage of a single nucleotide base pair
- usually spontaneous or from environmental influences
what are chromosomal translocations? what do they result in and what can they create?
type of protooncogene turning to oncogene method
chromosome breaks, relocates, and unites with another chromosome.
often results in overproduction of proteins associated with gene
can create new “chimeric” genes- philadelphia chromosome
what is gene amplification and what does it lead to
type of protooncogene turning to oncogene method
accelerating replication of genes, leading to overproduction of proteins associated with that gene.
through what three methods can protooncogenes become oncogenes
point mutation, chromosomal translocations, gene amplification
Define oncogenes. What do they encode and what do they disturb?
Genes that promote UNregulated cell growth and development, inhibit cell death.
They encode growth factors to promote cell division.
Disturbing cell surface receptors and cell-to-cell communication.
Encoding proteins to alter cell cycle, restrict apoptosis, and impact differentiation.
what are the two ways to name an oncogene?
Viral onc = denoted with v, ex; v-src
Cellular onc = denoted with c, like c-neu
What are some general types of genetic mutations for chromosomes?
Duplication, Inversion, Deletion, Insertion, Translocation.
See slide 22 for visual.
What two events are required for cancer to develop and then progress?
Initiating event
Promoting event
Define initiating event and what cells are most susceptible.
Initiating events are the event that causes a mutation in a cell. This is usually caused by a carcinogenic agent or a sporadic mutation.
The cells most susceptible are the ones actively synthesizing.
Define promoting event and a common cause.
It is the event that causes the cell to actively grow and reproduce more. (expansion of g+r)
Most commonly caused by chronic inflammation.
Also, complete carcinogens can do both initiation and promotion of neoplastic transformation.
define immunologic response as a host factor
functional immunity allows for destruction of abnormal “self” cells
(immuno response) many cancer cells express what
abnormal HLA-1 surface antigens that can be recognized by the body
what does impaired immunity cause
less ability to destroy tumor cells
what type of patient has higher rates of cancer?
many immunosuppressed patients such as HIV/ AIDS patients
Define Progression in terms of cancer.
Extension of promotion phase.
Important:
Cell no longer requires the promoter to be present AND
Cell acquires ability to invade tissue, metastasize, and grow autonomously.
What are the host factors that affect cancer susceptibility?
Immunologic response
Age
Chronic Inflammation
Genetic Predisposition
Genetic Disease
Hormones
why is age a host factor
increasing age increases incidence of cancer
Older people have accumulated more mutations/DNA damage.
Increased methylation of genes, which turns them OFF.
Weaker immune responses overall.
Why does having chronic inflammation increase your rates of neoplasia
During chronic inflammation, we have higher numbers of phagocytes floating around producing free radicals to destroy invaders but they can also damage other healthy cells while protecting us.
Inflammation also = cell proliferation, increased growth factor,
more angiogenesis,
increased nutrients and oxygen,
increased ability to grow and spread due to tissue remodeling.
what is genetic predisposition? does it mean someone will for sure get cancer?
genetic predisposition means its possible to see familial tendencies for cancer
does NOT mean someone is guaranteed to get cancer!
what is genetic predisposition due to?
inherited factors that increase the likelihood of neoplasia
- inefficient breakdown and disposal of carcinogens
- altered ability for DNA repair
-impaired cell proliferation and differentiation
what are carcinogens
substance, agent, organism capable of causing cancer
what are BRCA genes and what is the genetic predisposition of them?
BRCA-1 and BRCA-2 genes are tumor suppressor genes. They are inherited mutations that greatly increase the risk of multiple cancers
** especially breast and ovarian
what are the risks of the general population to get breast/ovarian cancer and the risks of getting breast/ovarian cancer with BRCA 1, 2 genes?
general population: 12% of women will get breast cancer and 1.4% will get ovarian cancer
BRCA-1: 55-65% will get breast cancer and 39% will get ovarian cancer
BRCA-2: 45% will get breast cancer and 11-17% will get ovarian cancer
Which of the two BRCA genes results in higher incidences of breast/ovarian cancer?
BRCA1,
which has a 55-65% breast cancer rate, 39% ovarian.
what are benign tumors? can they turn into malignant tumors?
increased abnormal cell growth but no ability to invade other tissues or spread (metastisize) to other areas
-some but not all can progress to malignant tumors