Lecture 21: Cancer

Question 1

What are carcinomas?

Answer 1

Tumours derived from epithelial cells

Question 2

What are squamous cell carcinomas?

Answer 2

Tumours arising form epithelial cells that form protective layers

Question 3

What are adenomas and adenocarcinomas?

Answer 3

Tumours arising from secretory epithelial cells

Question 4

What is the difference between adenomas and adenocarcinomas?

Answer 4

Adenomas are benign Adenocarcinomas are malignant

Question 5

What is the process of cancer development?

Answer 5

1. Normal epithelium
2. Hyperplastic epithelium
3. Adenomas which are benign
4. Carcinomas which are malignant
5. Invasion and metastasis

Question 6

What are the 10 hallmarks of cancer?

Answer 6

Sustaining proliferative signalling
Evading growth suppressors
Avoiding immune destruction
Enabling replicative immortality
Tumour promoting inflammation
Activation invasion and metastasis
Inducing angiogenesis
Genome instability and mutation
Resisting cell death
Deregulating cellular energetics

Question 7

How do cancer cells get their hallmarks?

Answer 7

Mutations in oncogenes and tumour suppressor genes

Question 8

How do genetic mutations go on to disrupt tissue homeostasis?

Answer 8

1. Mutated genes
2. Altered gene expression profiles
3. Dysfunctional protein networks
4. Abnormal cell function
5. Loss of tissue homeostasis

Question 9

How do retroviruses work?

Answer 9

1. RNA genomes are converted to DNA by reverse transcription
2. DNA integrates into host chromosomes and new viral genomes can be synthesised
3. V-src is responsible for turning normal cells into cancer cells

Question 10

What is meant by an oncogene?

Answer 10

A gene with the potential to cause cancer

Question 11

What was the first oncogene to be disovered?

Answer 11

v-src

Question 12

What is Ras?

Answer 12

Viral oncogene
Cellular cancer causing gene

Question 13

What is sporadic retinoblastima?

Answer 13

No family history
One eye
Low risk of other tumours

Question 14

What is familial retinoblastoma?

Answer 14

Family history
Both eyes
High risk of other tumours

Question 15

What does the retinoblastoma protein act as?

Answer 15

A tumour suppressor gene

Question 16

How does RB regulate the cell cycle?

Answer 16

1. Inhibits transcription factor E2F
2. When active Rb binds to E2F to prevent cell cycle progression
3. If Rb is absent E2F is always active and drives entry into S phase even in absence of mitogens

Question 17

What is neurofibromatosis?

Answer 17

Familial cancer syndrome caused by NF1 mutations
Causes Ras to be constitutively active

Question 18

What results from a mutation of the Wnt pathway?

Answer 18

Colon cancer

Question 19

Why is Wnt signalling needed in the crypt?

Answer 19

Maintaining intestinal cell populations
Regulating proliferation and differentiation

Question 20

What occurs if wnt signals are out of range in normal cells?

Answer 20

B-catenin is off
Cyclin D1 is off
Stop proliferating and differentiate
Migrate up and out

Question 21

What occurs if the wnt signals are in range?

Answer 21

B catenin is on
Cyclin D1 is on
Proliferation

Question 22

What occurs if the wnt signals are out of range in cancer?

Answer 22

Bcatenin remains on Cyclin d1 remains on
Keep proliferating without differentiating and remain there
Causes cancer

Question 23

How does TGF beta signalling act as an inhibitory pathway?

Answer 23

TGF-B signalling brakes the cell cycle
It is a tumour suppressor
If it mutates it can cause cancer

Question 24

How can Ras cause cancer?

Answer 24

If a single Ras allele is mutated the downstream pathway can get stuck on
This causes continuous growth and causes cancer to grow