Anti-Cancer Drugs Flashcards
what is cancer?
a group of diseases involving abnormal cell growth with the potential to invade or to spread to other parts of the body
leading cause of death in Canada
what are the top three types of cancers in females? in males?
female: breast, lung, colorectal
male: prostate, colorectal, lung
what age category is affected most by cancer? name an exception
older people
exception: testicular
what are 4 different fates of a cell?
stem cell renewal
differentiation
growth/quiescence
death
what occurs in cancerous cells regarding cell division?
unregulated cell division
can go on to be benign (non-cancerous; no effect on surrounding tissue) or malignant (cancerous; invades surrounding tissue)
a cell can also break away and start a new tumour elsewhere (metastasis)
what causes a cell to have uncontrolled cell division?
accumulation of a group of mutations that are enough to overdrive cell division
what are 7 hallmarks of cancer?**
1) self-sufficiency in growth signals
2) insensitivity to anti-growth signals
3) evading apoptosis
4) limitless reproductive potential
5) sustained angiogenesis
6) tissue invasion and metastases
7) genomic instability
what kind of mutations would occur that could affect cell growth?
1) deactivate DNA repair
2) inactivate tumour suppressor genes
3) activate pro-oncogenes
what is the minimum amount of gene mutations that usually occurs when cancer is formed? how many often occur?
5 mutations
often 6-9
is cancer hereditary?
no, but we can inherit dispositions (susceptibility) to cancer
what increases the frequency of cancer?
increases in mutation rate or genomic instability
what is aneuploidy?
presence of abnormal number of chromosomes in the cell
what are some inherited cancer syndromes?
p53, BRCA1 and 2, MMR (mismatched pair)
what factors can influence the genetic/developmental component of etiology of cancer?
inherited cancer syndromes
immune deficiency syndromes (enhanced predisposition)
polymorphisms (influence risk, occurrence, progression, and treatment)
what factors can influence the nurture component of etiology of cancer?
radiation chemotherapy viruses and bacteria (H. pylori, EBV) repeated injury (acid reflux, hepatitis) workplace/home exposures other environmental/lifestyle factors
what are some environmental factors that influence the etiology of cancer?
food additives (nitrites)
pollution (asbestos)
occupational (benzene)
industrial (hydrocarbons - soot)
what lifestyle factors influence the etiology of cancer?
tobacco
alcohol
diet (obesity)
viruses (HPV, HIV)
what initiator-promoter situations would lead to cancer? which wouldnt?
cancer:
initiator first shortly followed by promoter
initiator followed by a promoter later on
no cancer:
promoter comes before the initiator
initiator followed by little promotions throughout
what are tumour initiators?
mutagens; x rays, ultraviolet light, and DNA alkylating agents
what are tumour promoters?
proliferation inducers; phorbol esters, inflammation, alcohol, estrogen and androgens, EBV
describe dysregulated cell cycle in cancer?
cells divide when they are not supposed to
cells divide in a place they are not supposed to
what are the 5 phases of cell cycle?
G1 S G2 M G0
what is the G1 phase?
gap phase
cell grows and prepares to synthesizes DNA
what is the S phase?
synthesis phase
cell synthesizes DNA
what is the G2 phase?
second gap phase
cell prepares to divide
what is the M phase?
mitosis phase
cell division occurs
what is the G0 phase?
arrest/quiescent phase
cell is in a resting state
what are the 3 different checkpoints in cell cycle?
G1/S checkpoint - cell monitors size and DNA integrity
G2/M checkpoint - cell monitors DNA synthesis and damage
M checkpoint - cell monitors spindle formation and attachment to kinetophores
what are two different protein complexes involved in the cell cycle?
cyclins - levels change throughout cell cycle
cyclin dependent kinases - stable levels
what is the function of cyclins and Cdks?
ability to drive through the checkpoints in cell cycle
how do Cdks work?
bind to correct cyclin in order to function
act as kinases (add phosphate group) and convert them from an off to an on state
cause a cascade of kinases adding phosphates to other proteins to activate them, that eventually leads to transcription of genes (transcription factors)
what is the normal function of oncogenes?
cell growth and gene transcription; drive cell cycle
other common functions: growth factors, growth factor receptors, signal transducers nuclear receptors, transcription factors, anti-apoptotic factors
what is the normal function of tumour suppressor genes?
DNA repair, cell cycle control, cell death
what are oncogenes?
a gene, that when mutated gains a function or is expressed at abnormally-high levels and/or high activity (often kinases, transcription factors or growth factors/receptors)
what are tumour suppressor genes?
encodes for a protein that is involved in suppressing cell division and when mutated, it is no longer functional
what is often the first mutation in developing cancer?
mutation to tumour suppression genes
what is p53?
a classic tumour suppressor (50% of all cancer from p53 mutation)
what does p53 do?
senses genomic damage (via ATM) and halts the cell cycle and initiates DNA repair
if DNA is irreparable, it will initiate the cell death process
what is Rb and what does it do?
a classic tumour suppressor
binds to a protein (E2F1) that inhibits the function of E2F1 (G1/S cell cycle transition)
ie: crucial cell cycle checkpoint
what is HER2/neu? what type of cancer is it typically associated with?
amplified oncogene; a growth factor receptor breast cancer (25-30% of cancer cases over-express it)
what is the treatment against HER2/neu?
Herceptin - binds to and inhibits function of receptor
what is Ras?
a frequently mutated oncogene; a growth factor receptor
transduces multiple cell signals
which oncogene is the most common to be mutated?
Ras gene
what happens when Ras is mutated?
signal-independent hyperactivation of expression, cell proliferation, and anti-apoptotic signalling
what are some examples of a DNA repair defect? why are they significant?
base modification Single strand break bulky lesion cross-link of base pairs double strand break 95% of all cancers have at least 1 or more DNA repair defects
what kind of defects can happen to the chromosome to cause genomic instability?
gross translocations
loss/gain of chromosome parts
what is the difference between pseudodiploid and hyperdiploid?
pseudo - 2 RNA genomes per virion but give rise to 1 DNA copy in the infected cell
hyper - more than a diploid number of chromosomes
what is the difference between early and late stages of tumour growth?
early - high growth fraction; short doubling time
late - low growth fraction; long doubling times
when is chemotherapy most effective?
high growth fraction
define the following terms:
carcinoma
sarcoma
leukemia/lymphoma/myeloma
carcinoma - epithelial
sarcoma - mesenchyme
leukemia etc - hematopoietic
what is hyperplasia?
increased number of cells
what is hypertrophy?
increased size of cells
what is dysplasia?
disorderly proliferation
what is neoplasia?
abnormal new growth
what is anaplasia?
lack of differentiation
what are some examples of carcinoma?
lung breast colon bladder prostate
what are some examples of sarcoma?
fat
bone
muscle
what are the 4 stages of tumour progression?
1) hyperplasia
2) dysplasia
3) carcinoma in situ (does not cross basal lamina)
4) cancer (malignant tumours)
what are 4 differences between benign and malignant tumours?
benign (non-invasive): - well defined borders - well differentiated - regular nuclei - rare mitoses malignant (invasive/metastatic): - irregular borders - poorly differentiated - irregular, large nuclei - more frequent and/or abnormal mitoses