2. Biology of Tumors Flashcards
(23 cards)
What are the three main types of genes that control cell proliferation?
Proto-oncogenes, tumor suppressor genes, mismatch repair genes
Examples: HER2-neu (proto-oncogene), p53 (tumor suppressor), MLH1 (mismatch repair)
Give 3 examples of proto-oncogenes and their related cancers
k-ras (pancreatic cancer), n-ras (melanoma), b-raf (melanoma), Her2-neu (breast cancer)
Proto-oncogenes are genes that can promote cancer when mutated.
What is the clinical significance of the Rb tumor suppressor gene?
Mutated in retinoblastoma and osteosarcoma; regulates G1/S checkpoint
Rb is crucial for controlling cell cycle progression.
Name all cyclins and their corresponding CDKs with cell cycle phases
Cyclin D/CDK4/6 (G1 phase), Cyclin E/CDK2 (G1/S transition), Cyclin A/CDK2 (S phase), Cyclin B/CDK1 (G2/M transition)
Cyclins are proteins that regulate the cell cycle by activating CDKs.
What happens when p53 is mutated?
Loss of G1/S checkpoint control → damaged cells proliferate
Associated with Li-Fraumeni syndrome and >50% cancers.
Explain the 3E Theory with clinical examples
Elimination (HPV clearance), Equilibrium (dormant micrometastases), Escape (PD-L1 expression in lung cancer)
The 3E Theory describes stages of tumor immunity.
How do NK cells recognize tumor cells?
Detect missing MHC class I via KIR receptors
MHC class I is often downregulated in tumor cells.
Compare all Bcl-2 family members and their roles
Anti-apoptotic: Bcl-2, Bcl-xL; Pro-apoptotic: Bax, Bak, Bok; Regulators: Bad, Bid
Bcl-2 family members play critical roles in regulating apoptosis.
What caspase cascade occurs in extrinsic apoptosis?
Fas-FasL → FADD → Caspase-8 → Caspase-3
This pathway is also known as the death receptor pathway.
Which cancers overexpress Bcl-2?
Follicular lymphoma, CLL
Follicular lymphoma is associated with translocation t(14;18) and CLL can be treated with venetoclax.
Compare all 5 DNA repair mechanisms
BER (base damage), NER (UV damage), MMR (replication errors), NHEJ (error-prone DSB repair), HR (precise DSB repair)
Each mechanism addresses different types of DNA damage.
What cancers are associated with BRCA1/2 mutations?
Breast, ovarian, prostate, pancreatic
These cancers are sensitive to PARP inhibitors.
List 4 molecular mechanisms of chemo resistance
1) Drug pumps (P-glycoprotein) 2) Target mutation (EGFR T790M) 3) Enhanced repair 4) Alternative pathways
These mechanisms help cancer cells evade the effects of chemotherapy.
What is primary vs secondary resistance?
Primary: Pre-existing resistant clones; Secondary: Acquired during treatment
Examples include BCR-ABL T315I (primary) and EGFR T790M (secondary).
Match these targeted drugs to their molecular targets: Trastuzumab, Vemurafenib, Olaparib, Imatinib, Cetuximab
Trastuzumab (HER2), Vemurafenib (BRAF V600E), Olaparib (PARP), Imatinib (BCR-ABL), Cetuximab (EGFR)
Targeted therapies focus on specific molecular targets in cancer treatment.
What is the significance of microsatellite instability?
MMR deficiency → Lynch syndrome → colorectal/endometrial cancer
Microsatellite instability is a marker for certain types of cancer.
Why are testicular tumors highly curable?
Extreme sensitivity to chemo
This is due to intact p53 and high apoptotic potential of testicular tumors.
What makes glioblastoma resistant?
Blood-brain barrier, tumor heterogeneity, MGMT repair enzyme
These factors contribute to the treatment challenges in glioblastoma.
Function of TGF-β in cancer?
Immunosuppression
TGF-β can inhibit immune responses, allowing tumors to evade detection.
Function of VEGF in cancer?
Angiogenesis
VEGF promotes the formation of new blood vessels to supply tumors.
Function of TNF-α in cancer?
Inflammation
TNF-α is involved in the inflammatory response and can influence tumor growth.
Function of IL-6 in cancer?
JAK/STAT signaling
IL-6 is a cytokine that can promote cancer cell growth and survival.
Role of telomerase in cancer?
Immortalizes cells
Active in 90% cancers, silent in normal cells.
