Lectures 1-2

Question 1

What is a tumor?

Answer 1

A group of cells which display unregulated proliferation. Also known as a neoplasm.

Question 2

What is metastasis?

Answer 2

Metastasis is the ability of a malignant tumor to form 2 degree tumors (metastases) at other sites in the body.

Question 3

How does Metastasis occur?

Answer 3

It occurs when small clusters of cancerous cells dislodge from the primary tumor to invade the blood or lymphatic vessels and are carried to distant sites, taking up residence and proliferating.
The potential to do this is called Metastatic potential.

Question 4

Tumor arise from what kind of tissues?

Answer 4

Either epithelial tissues or non-epithelial tissues.

Question 5

Epithelial tumors:

Answer 5

-Are called Carcinomas.
-They make up 80-90% of cancers eg. Breast, colon, prostate, lung, stomach, skin, oesophagus, liver, ovary, gallbladder and urinary.

Question 6

Non-epithelial tumors:

Answer 6

-Leukemia, Lymphoma and multiple myeloma (9% of all cancers) are malignant tumors of hematopoietic cells derived from bone marrow.
-Sarcoma (1% of cancers) arise from a variety of mesenchymal cell types.
-Cells that form part of the central and peripheral nervous systems. Includes gliomas, glioblastomas, neuroblastomas, medulloblastomas. Makes up 1.3%.

Question 7

Oncogenes vs Tumor suppressor genes:

Answer 7

-Oncogenes are usually “gain of function mutations” generally dominant eg cMYC
-Tumor suppressor genes (TSGs) are usually “loss of function mutations” generally recessive eg Rb

Question 8

What are proto-oncogenes?

Answer 8

Genes that encode elements of the cell’s signal transduction network and parts of the cell cycle control system. When mutated they can allow cancer to occur.

Question 9

Proto-oncogenes can encode:

Answer 9

-Growth Factors
-Growth Factor Receptors
-Signal Transduction Molecules
-Nuclear Proteins

Question 10

2 types of Signal Transduction Molecules:

Answer 10

1. Cytoplasmic membrane associated proteins:
   src (tyrosine kinase)
   ras (GTP-binding protein)
2. Soluble signal transduction proteins:
   raf (serine/threonine kinase)

Question 11

2 nuclear proteins:

Answer 11

1. c-myc (gene regulatory protein, HLH family)
2. jun + fos (form AP-1)

Question 12

What does activation of oncogenes lead to

Answer 12

Generally lead to increased cell division and growth, lack of apoptosis, increased cell
motility, invasion and loss of differentiation i.e Cancer

Question 13

How can oncogenes become activated.

Answer 13

-genetic/point mutations
-chromosomal translocations
-gene amplification
-epigenetic factors
-Increased protein stability

Question 14

Point mutation:

Answer 14

Results in gene being constitutively active or increased activity e.g Hras

Question 15

Gene Amplification:

Answer 15

Normal protein is overproduced e.g HER2

Question 16

Chromosome translocation:

Answer 16

Gene moves to a strong enhancer which leads to increased protein expression e.g c-myc in Burkitt’s lymphoma

Question 17

2 observations that suggest tumors derived from a single abnormal cell:

Answer 17

1. Karyotyping/DNA Analysis
2. X Chromosome inactivation

Question 18

Multistep Nature of Cancer:

Answer 18

The tendency of untreated tumors to develop from benign or small to malignant, large tumors over time.

Question 19

What happens to tumor cells during lag phase?

Answer 19

They undergo a succession of changes.(multiple genetic/epigenetic changes)