Anticancer Flashcards
How does a cell become cancerous?
When cell division becomes unregulated, can become benign (tumor has no effect on surrounding tissue-non-cancerous), malignant (tumor invades surrounding tissue-cancerous) or metastatic (cells break away and start a new tumor elsewhere-cancerous)
What are some hallmarks of cancer?
Self-sufficiency (operates independent) in growth signals
Insensitivity to anti-growth signals
Evading apoptosis
Limitless reproductive potential
Sustained angiogenesis (forms new blood cells)
Tissue invasion and metastatses
Genomic instability
How is cancer a genetic disease?
Not a hereditary disease but can pass a predisposition to develop
Arises from an accumulation of genetic changes (somatic mutations, single cells) in proteins that are involved in regulating the cell cycle
Most cancers incur a minimum of 5 different gene mutations
What are the genetic factors in breast/ovarian cancer?
BRCA 1/2 mutations
It is a normal gene is activated by ATM kinase and targets p53
What can cause cancer?
Nitrites, asbestos, benzene, hydrocarbons (soot), tobacco, alcohol, obesity, viruses (HPV, HIV), estrogen
What is the promoter-initiator model?
An initial mutation event is an initiator. It must occur first, followed by a strong promotor (lifestyle) to drive the cancer anytime after
What are some examples of tumor initiators (mutagens)?
X-rays, ultraviolet light, DNA alkylating agents
What are some examples of tumor promoters (proliferation inducers)?
Phorbol esters (croton oil), inflammation (hepatitis), alcohol, estrogens and androgens, epstein-barr virus
What are the phases of the cell cycle?
G1 (gap): the cell grows and prepares to synthesize DNA
S (synthesis): cell synthesizes DNA
G2 (2nd gap): cell prepares to divide
M (mitosis):cell division occurs
G0 (arrest): when the cells is in a resting state (can be in this or G1 depending what it wants to do)
What are the 3 checkpoints of the cell cycle?
G1/S: Cell monitors its size and DNA integrity
G2/M: Cell monitors DNA synthesis and damage
M: Cell monitors spindle formation and attachment to kinetochores
What are cyclins and cyclin dependent kinases (Cdks)?
Cyclin surges and function of CDk (stable levels) determine the drive of the cell through the cell cycle checkpoints
How do cyclins and Cdks work?
Cdks must bind the correct cyclin in order to function and add phosphate groups to proteins to “turn them on”. This causes a cascade of kinases adding phosphates to other proteins to activate them, eventually leading to the transcription of genes.
What are oncogenes? What happens to them in cancer?
Normally function in cell growth and gene transcription, in cancer they are activated due to a mutation giving it a new function or expressed at abnormally high levels
myc, ras, src, abl, bcl2, HER2/neu
What are tumor suppressor genes? What happens to them in cancer?
Normally function in DNA repair, cell cycle control and cell death, in cancer they are inactivated due to a mutation
Causes a “mutator phenotype”, which causes mutation rates to increase
p53, Rb, APC, MEN1, NF1
How does tumor suppressor p53 work?
Senses genomic damage (via ATM), halts the cell cycle and initiates DNA repair.
If the DNA is irreparable, p53 will initiate the death process.
How does tumor suppressor Rb work?
Binds to E2F1 and stops it from initiating the G1/S cell cycle transition
Rb is a crucial cell cycle checkpoint
How does oncogene ras work?
It is a growth factor that is responsive to small GTPase and transduces multiple cell signals
What are some DNA defects that must be repaired?
Base modifications, Single strand breaks, bulky lesion, cross link, double strand breaks
What is the philadelphia chromosome?
An oncogenic rearrangement that is associated with leukemias
BCR-ABL tyrosine kinase function
What is used to treat philadelphia chromsome CML?
Imantinib is an Abl-kinase targeted inhibitor
What is used to treat HER2/neu breast cancers?
Herceptin binds and inhibits the function of this receptor
What are the stages of tumor growth?
Early: High growth fraction, short doubling times
Late: Low growth fraction, long doubling times
Chemo is most effective when growth fraction is high (early stages)
What is the nomenclature for benign tumors?
-oma
Adenoma, fibroma, lipoma
What is the nomenclature for malignant cancer?
Carcinoma or sarcoma
Adenocarcinoma, fibrosarcoma