cancer

Question 1

Cells of multicellular organism

Answer 1

• Self-sacrifice is the rule
• Committed to collaboration
• To coordinate their behavior, the cells send, receive, and interpret an elaborate set of extracellular signals that serve as social controls, directing cells how to act

Question 2

healthy cell

Answer 2

rest, grow, divide, differentiate, die

Question 3

divide repeatedly out of control even though they are not needed (failure of cellular regulation)

Answer 3

Cancer

Question 4

cancer cell structure

Answer 4

small cytoplasm
multiple nuclei
multiple and large nucleoli
coarse chromatin
large no. of dividing cells
large nucleus to cytoplasm ratio
variation in size and shape
loss of normal cell features
disorganized arrangement
poorly defined tumor bound

Question 5

normally activates cell division

growth factor genes become oncogenes (cancer-causing) when mutated

if switched ON can cause cancer

Answer 5

Proto-oncogenes

Question 6

examples of Proto-oncogenes

Answer 6

RAS (activates cyclins), MYC, EGFR

Question 7

loss of function

Answer 7

Tumor suppressor genes

Question 8

Tumor suppressor gene that regulates cell growth, proliferation and apoptosis by inhibiting the P13K/AKT/mTOR signaling pathway

Answer 8

PTEN

Question 9

Homologous recombination,
checkpoint control

Associated with hereditary
breast and ovarian cancer

Answer 9

BRCA1/2 (Genome maintenance
genes)

Question 10

hallmarks of cancer

Answer 10

sustain proliferative signaling

evade growth suppresors

activate invasion and metastasis

enable replicative immortality

induce angiogenesis

Question 11

Promotes proliferation

Answer 11

RTK/RAS/RAF/MEF/ERK pathway

Question 12

Promotes survival and growth

Answer 12

P13K/AKT/mTOR pathways

Question 13

Regulates cell fate, stemness

Answer 13

WNT/ẞ-catenin pathways

Question 14

often cause ligand-independent
activation, receptor amplification, or GTPase inactivation 3

Answer 14

Oncogenic mutations

Question 15

Cancer is essentially a

Answer 15

failure of cell division control

Question 16

What control is lost?

Answer 16

lose checkpoint stops

Question 17

p53 Protein and Cancer

Answer 17

Halts cell division upon detecting damaged DNA

Stimulates DNA repair enzymes

Forces cell into G0 (resting phase) or keeps it in G1 arrest

Can trigger apoptosis (programmed cell death) of damaged cells

All cancers must inactivate p53 to bypass these protective mechanisms

Question 18

p53 pathway

Answer 18

Triggers: DNA damage, cell cycle abnormalities, hypoxia
p53 is activated (released from inhibition by mdm2)

Two possible outcomes:
Cell Cycle Arrest → DNA Repair → Cycle Restart
Apoptosis → Death of damaged cells

Final Result:
➤ Maintains cellular and genetic stability
🧬 p53 must be inactivated for cancer to develop

Question 19

“Go-ahead” Signals in Cell Cycle Regulation

Answer 19

Controlled mainly through phosphorylation

Kinase enzymes activate or inactivate signaling pathways

Example:
Loss of p16 function → Overproduction of cyclin D → Promotes unchecked cell cycle progression

Question 19

activator of transcription of proteins needed for DNA synthesis

Answer 19

E2F

Question 20

repressor of transcription of proteins required for DNA synthesis

Answer 20

RB and E2F

Question 22

p16, CycD, CDK4

Answer 22

inactive kinase

Question 23

CycD, CDK4

Answer 23

active kinase

Question 24

Inactivation of p53

Answer 24

Impaired mitochondrial outer membrane permeabilization

Question 25

mimics Bcl-2 (inhibits apoptosis)

Answer 25

Cancer can produce BcL-2 or protein

Question 26

How do cancer cells evade apoptosis?

Answer 26

Inhibit expression of Apaf-1 gene → prevents formation of apoptosome Block T-cells’ FasL or kill cytotoxic T-cells using FasL → prevents immune-mediated apoptosis

Question 27

Invasion/migration into new tissues, establishing secondary areas of proliferation

Answer 27

Metastatis

Question 28

mass of abnormal cells

Answer 28

Tumor

Question 29

abnormal cells remain at original site as a lump, hold together by cell adhesion molecules p53 has halted cell divisions

Answer 29

Benign tumor

Question 30

What characterizes a malignant tumor (cancer)?

Answer 30

Cancer cells leave the original site Lose attachment to nearby cells Spread via blood & lymph to other tissues Form new tumors in other parts of the body → Metastasis

Question 31

What must cancer cells do to metastasize?

Answer 31

Alter cell adhesion molecules and degrade the extracellular matrix and basal lamina (epithelial-to- mesenchymal transition)

Question 32

some of the proteins secreted by cancer cells to degrade the ECM

Answer 32

MMP and plasminogen activator

Question 33

tumor growth requires

Answer 33

formation of new blood vessels

Question 34

steps for angiogenesis

Answer 34

1. Degradation of basal lamina that surrounds the capillary 2. Migration of endothelial cells 3. Division of endothelial cells 4. Formation of new basement membrane

Question 35

Growth factors (angiogenic properties)

Answer 35

* Basic fibroblast growth factor * Transforming growth factorα * Vascular endothelial growth factor (VEGF)

Question 36

How is cancer cell metabolism altered?

Answer 36

Cancer cells show the Warburg effect: ↑ Glucose uptake and lactate production, even with oxygen present Lifestyle factors (e.g., diet, exercise) can help in cancer prevention