Angela's cancer biology, molecular biology

Question 1

Senescence - continued telomere erosion in cells will lead to death in all but immortalized cells. By what mechanism do immortalized cells overcome this?

Answer 1

Through reactivation of telomerase

Question 2

What is telomerase?

Answer 2

RNA dependent DNA-polymerase that synthesizes telomeric DNA

Question 3

What are the 2 components of telomerase?

Answer 3

An RNA template and hTERT

hTERT: human telomerase reverse transcriptase

Telomerase consists of two essential components:
1) the functional RNA component (in humans called hTR or hTERC), which serves as a template for telomeric DNA synthesis
2) a catalytic protein (hTERT) with reverse transcriptase activity

Question 4

What is hTERT?

Answer 4

hTERT: human telomerase reverse transcriptase
a catalytic subunit of the enzyme telomerase, which, together with the telomerase RNA component (TERC), comprises the most important unit of the telomerase complex.

expression of hTERT is repressed after embryogenesis

Question 5

Mitotic cell cycle , name 5 phases?

Answer 5

GO: rest, not dividing

G1 phase: protein synthesis

S phase: DNA synthesis/replication

G2 phase: growth/prep to divide

Mitosis: chromosomal segregation in mitosis, cell separation in cytokinesis

Question 6

What is least associated with cancer cells?

Choices:
a. Disjunction
b. Requirements of increased substances for proliferation
c. Contact inhibition

Answer 6

CONTACT INHIBITION

Contact inhibition is a process of arresting cell growth when cells come in contact with each other
Disjunction is the normal separation or moving apart of chromosomes toward opposite poles of the cell during cell division

Question 7

Where does angiostatin work?

Answer 7

its an angiogenesis inhibitor, direct action against endothelial cells.

Question 8

Where does FAK work?

Answer 8

focal adhesion kinase (FAK) is a cytoplasmic protein tyrosine kinase that promotes tumor metastasis. Can also act in nucleus

FAK signaling promotes cell motility and invasion and activation of matrix-degrading metalloproteinases, thus stimulating the ability of cells to invade through the ECM.
It is a positive regulator of cell growth by triggering both survival and proliferative signals.

Question 9

When in the cell cycle are cells diploid?

Answer 9

G1 and G0

Question 10

When in the cell cycle are cells tetraploid?

Answer 10

G2 and M

Question 11

The steps of cancer metastasis include:

Answer 11

proliferation
angiogenesis
invasion
embolization or circulation
transportation
adherence at distant organs or vessels

Question 12

What are cadherins?

Answer 12

transmembrane glycoproteins that mediate cell-cell communication via calcium dependent interactions

Mnemonic: cad- Ca Dependent her -hear (like communication)

Question 13

What are integrins?

Answer 13

transmembrane glycoproteins that serve as signaling molecules for regulation of apoptosis, gene expression, proliferation

Question 14

What part of the cell cycle does a labeling index measure?

Answer 14

S phase fraction (proliferating cells)

Question 15

What percentage of cells in human malignancies are mitotically active?

Answer 15

3-15%

Question 16

How does a labeling index work?

Answer 16

Uses autoradiography to detect H-thymidine in cellular DNA

A labeling index measures the proportion of cells in a sample of tissue that are producing DNA (#cells in S phase).

Question 17

What is Flow cytometry used for?

Answer 17

Flow cytometry is used to analyze cell cycle and growth fraction

It can analyze replication states using fluorescent dyes to measure the four distinct phases of the cell cycle. Along with determining cell cycle replication states, the assay can measure cell aneuploidy associated with chromosomal abnormalities.

Question 18

Which phase of the cell cycle has the highest amount of protein synthesis?

Answer 18

G1

Because it prepares for replication in S

Question 19

Which type of cells does a labeling index identify?

a. G1
b. S phase
c. G2
d. SM

Answer 19

S phase

Question 20

When is a cell tetraploid?

Answer 20

G2 - M

Question 21

When is a cell diploid?

Answer 21

G1

Question 22

How do you humanize a mouse antibody?

Answer 22

To make it humanized, must graft complementarity-determining region (CDR), the hypervariable domain, that determines specificity, from a mouse antibody onto a human variable region framework, creating humanized antibodies

You can also reduce the immunogenicity of the mouse antibodies using genetic engineering to generate chimeric antibodies containing human constant domains (Fc) and the mouse variable domains (Fv) to retain the specificity

Question 23

What do proteolysis, angiogenesis, and cell migration have to do with tumor biology?

Answer 23

Proteolysis - proteases synergize to establish an environment that allows tumor cells to thrive, invade into surrounding tissue, and colonize distant organs
Angiogenesis - growth of new blood vessels that tumors need to grow
Migration - occurs during the whole cascade of cancer development and is important during invasion, the initial step of metastasis. Following chemotactic migration, a cancer cell invades into the surrounding tissue and the local vasculature.

Question 24

What is the role of Rb (retinoblastoma) gene?

Answer 24

Retinoblastoma (RB) is a tumor suppressor known as a master regulator of the cell cycle. It is a transcriptional regulator which interacts with the E2F family of transcription factors and represses cell cycle progression from G2 to M phase.

Question 25

What is the role of CHK1 and CHK2?

Answer 25

CHK1 and CHK2 are both activated upon DNA damage and can regulate cell division. CHK1 activity has been mostly implicated in the intra-S phase cell cycle checkpoint and the G2–M transition. CHK2 activity is associated with G1–S and G2–M arrests.