oncology/cancer cells Flashcards
what is the cell cycle
The cell cycle is a sequence of growth stages that a cell moves through for mitosis and regeneration. In order for cells to undergo mitosis, the cell must go through stages G0, G1, S, G2, and M.
Stage G0
The cell is at rest and is not actively engaged in the cell cycle.
Stage G1
Cells enter the cell cycle and prepare for deoxyribonucleic acid (DNA) replication. Proto-oncogenes, genes that control cell replication, are activated.
Stage S
Synthesis of structures occurs and the structures move to opposite poles in preparation for division into two separate cells. The 46 chromosomes reorganize as two separate sets of 23 chromosome pairs arranged at opposite poles. Two nuclear membranes develop around the two separate sets of 23 pairs.
Stage G2
Cells prepare to divide
Stage M
Mitosis is completed and 2 daughter cells are created
4 steps in cancer cells disregard of cycle rules
Cancer cells are constantly moving through the cell cycle stages.
No Checkpoints
No DNA errors recognized
No apoptosis
Cancer cells disregard the growth inhibitors released by neighboring cells.
As the cancer cells proliferate, they accumulate on top, around, and beside each other, take over boundaries of organs, crowd out normal cells, and may even break free and travel to distant body sites
what is differentiation
refers to the extent that neoplastic cells resemble normal cells both structurally and functionally.
what is lack of differentiation called
anaplasia, a term that indicates total cellular disorganization, abnormal cell appearance, and cell dysfunction.
How do cancer cells break Rules
Contact inhibition
++“I will respect your personal space”
–“Get out of my way!”
Cohesiveness
++“Stick with me & we’ll stay home”
–“I’m out of here!”
Communication
++“Ask the man next door to help!”
–Little-to-no communication
Proliferation control \++“Our goal = zero population growth!” Apoptosis (normal death) --Sometimes immortal Die unpredictably
Proliferation rate
++Predictable
–Unpredictable
Depends on differentiation
“Self” HLA antigens
++“Do no harm!”
–“Nonself” markers
Attack may be mustered
Characteristics of benign tumors
Differentiation
=Well-differentiated; resembles tissue of origin
Rate of Growth
=Progressive, slow
Local Invasion
=Cohesive cells, well-demarcated tumor, often encapsulated making it movable
Metastasis
=None
Tumor Core
=No necrosis
characteristics of malignant tumors
Poorly differentiated; does not resemble tissue of origin (anaplastic)
Erratic, slow to rapid
Invasive and infiltrating, surrounding normal tissue
Frequent metastasis
Can have necrotic core
what susbstances make up tumor markers
hormones
enzymes
antigens
genes
where can makers be found
blood
urine
csf
plasma membrane
Grades of malignant tumors
Grade I: cells are well-differentiated
Grade II: cells are moderately differentiated
Grade III: poorly differentiated or anaplastic cells
TNM system
T - tumor size, location, and involvement.
N - lymph node involvement.
M - metastasis to distant organs.
TMN Classification system
T
(Tumor size & Location)
T0: No evidence of primary tumor
TIS: Tumor in situ
T1-4: Progressive increase in tumor size or involvement
—
N
(Spread to nodes)
N0: No spread to regional lymph nodes
N1: Spread to closest or small number of regional lymph nodes
N2: Spread to most distant or numerous regional lymph nodes
M (Metastasis) M0: None M1: Yes ---
4 stage cancer class systme for patients
Stage 1: Confined to organ of origin Stage 2: Locally invasive Stage 3: Regional spread Stage 4: Spread to distant sites
4 phases of carcinogenesis
Initiation - alter of genes
Promotion – proliferating cells accumulate
Progression – further mutation
Metastasis – spread of cancer
Tumor suppressor genes
Normally function to restrain cell growth
Can also become defective and lose the ability to inhibit cell growth and division, thus allowing cancer formation.
p53 gene controls what
apoptosis
proto-oncogenes
genes that stimulate and regulate a cell’s movement through the cell cycle, resulting in cellular growth and proliferation.
when mutated, proto-oncogenes become oncogenes that stimulate constant, unrelenting cellular proliferation and cell cycling.
Carcinogens
Substances that cause development of cancer
Can alter cell DNA
Damage = cumulative!
classifications of carcinogens
known
probable
possible
what are promoters of cancer
Agents that promote development of cancer
Examples: Diet Alcoholic beverages Tobacco Hormones
Viral induced cancer
MOA - always involve the activation of growth-promoting pathways or inhibition of tumor suppressors in infected cells.
what do cancer cells secrete
vascular endothelial growth factor
2 types of tumors
Primary Tumor
Location – site of origin
Secondary Tumor
Location – not site of origin
what is seeding
tumor erosion and shedding into body cavities
what is implantation
direct expansion into adjoining tissue
2 primary routes of metastasis
lumphatic
vascular
lyphatic spread and 3 possible scenarios
First stop is the lymph system!
Cells trapped in lymph nodes
Three possible scenarios
Death
Dormancy
Flourish/proliferate
Vascular spread and first stop
Spread by Vascular Drainage
Penetrate local veins
And away it goes!
First stop??
Often liver
Why??
Recieves blood first
What happens?
Clumping – Trapping – Proliferating
metastasis for lung caner
bone/brain
metastasis for colon cancer
liver
metastasis for breast cancer
bone/brain/liver/lung
metastasis for prostate cancer
vertebrae
metastasis for melanoma
brain
