Lecture 7: Necrosis and Apoptosis

Question 1

Neoplasm:

Benign

Malignant

Answer 1

Neoplasm- new growth of abnormal mass of cells

Benign Growths- 
Slow-growing, 
remaining localized to site of region
Few Mits
Uniform throughout tumor

Malignant Growths- 
fast growing, 
can spread (Metastosis), 
Abnormal growth of tissues/unregulated growth
Ignores restraints of cell division
Can vary in shape and size
Many mits

Question 2

Cancer

Carcinomas

Sarcomas

Leukemia

Melanoma

Answer 2

Cancer= malignant neoplasm are classified according to tissue and cell types in which they originate

Carcinomas=
malignant tumors,
EPITHELIAL tissue,
can effect glands involved in secretion

Sarcomas=
malignant tumors 
CONNECTIVE tissue
Osteosarcoma= bone cancer
Chondrosarcoma=Cartilage cancer

Leukemia= Cancer of blood or bone marrow

Melanoma= Malignant tumor of melanocytes (in skin)

Question 3

Metastisis

Modes:

Answer 3

Metastisis: Distant spread of teh tumor cell into other tissue of the body

Modes-
Vascular: through veins
Lymphatic: through lymphatic vessels
Transcoelomic: Across coelomic space (between tissue)

Question 4

Tumor Formation

Answer 4

Colonal Evolution:
-Develops from rounds of mutation and proliferation

Stem cell:
-Tumors contain cancer stem cells (infinite proliferation potential)

Question 5

Karyotype and cancer

Answer 5

-Multiple translocations and abnormal number of chromosomes can indicate cancer

Question 6

Cell Death:

Necrosis

Apoptosis

Answer 6

Necrosis:

• Outcome in many injuries
• Inability to maintain homeostasis
• CELL SWELLING
• loss of plasma membrane integrity
• Cell contents released
• Surrounding tissue damage (inflammation)

Apoptosis:
(abnormal if loss of cells due to apoptosis (Immunodeficiency disorder)
-Cell suicide (development/throughout adulthood)
-Physiological: Development, tissue homeostasis
-Pathological: DNA damage, misfolded proteins
-Genetically mediated (Programmed cell death)
-CELL SHRINKING
-DNA aggregation
-Maintains plasma membrane integrity
-No surrounding tissue damage or inflammation

Question 7

Assessment of Necrosis (staining)

Answer 7

Propidium Iodid Staining (PI):
-live cell imaging
PI intercalates and labels DNA
PI is +, the plasma membrane is leaky (lost its integrity) and signifies nercrosis

Hematoxylin and Eosin Staining (H+E):

• Hematoxylin= Net charge +, attract - molecules
• Eosin= Net -, attracts + molecules

TEM- Can see discontinues plasma and organelle membranes

Biochemical- Can test for in blood serum when there is a loss of cells (High levels of lactate dehydrogenase) (LDH)

Question 8

Apoptosis (Processes=Intrinsic/extrinsic)

Answer 8

Form bleb protrusions as cell shrinks

Process intrinsic:

1) Phosphatidylserine moves from inner leaflet to outer leaflet
2) Membranes bleb
3) Condensed chromatin seen in nucleus
4) Cytochrome C released from mitochondria

Process Extrinsic= Immune response

1) Binding of ligand to death receptor
2) Recruitment of death adaptor proteins (FADD, TRADD)
3) Caspase cascade initiation via formation of death-inducing signaling complex (DISC)

Question 9

Caspase Cascade

Answer 9

Family of protease enzymes:

• cysteine-dependent aspartate-directed proteases
• Synthesized as inactive pre-cursors (Procaspases)
• Activated via proteolytic cleavage
• Target cytoplasmic and nuclear proteins and caspase-active DNAse

INVOLVED IN BOTH APOPTOSIS PATHWAYS

Question 10

Assessment of Apoptosis (how to tell it’s happening)

Answer 10

• Caspase Activity
• Annexin 5- Protein binding to phosphoserine on outerleaflet of plasma membrane
• DNA laddering
• TUNEL

Question 11

What diseases can result in improper apoptosis

Answer 11

Loss of cells:
-Immune deficiency/anemia

Non-renewing cells:

• Alzheimers
• Parkinson’s
• Myocardial infraction

Accumulation of cells:

• Malignant neoplasia (Cancerous abnormal cell growth)
• Autoimmune syndromes

Question 12

Describe pathways of Apoptosis

Intrinsic

Extrinsic

Answer 12

Intrinsic:

1) Death signal due to DNA damage
2) Apoptosis proteins inserted into mitchondria
3) Cyctochrome c released into cytoplasm from mitchondria to activate Apaf-1
4) Apoptosome forms (Apaf-1, Pytochrome c, Procaspase 9)
5) Caspase cascade (Activation of initiator caspase 9 and activation of effector caspases) this cleaves cellular proteins and DNA
6) Apoptosis = blebbing of plasma membrane

Extrinsic:

1) Binding of ligand to death receptor
2) Recruitment of death domain adaptor proteins (FADD, TRADD)
3) Formation of death inducting signaling complex (DISC)
4) Caspase cascade (Initiator caspases: caspase 8, Effector caspase: capase 3)

Question 13

How do tumor supressor supress genes

Answer 13

methyltransferase