Cancer/ Oncogenesis Info

Question 1

What are cancer cells?

Answer 1

Transformed cells capable of uncontrolled proliferation

Question 2

Cellular growth and proliferation are controlled by?

Answer 2

cytokines that upon binding to their respective receptors signal via cellular signaling pathways (MAP kinase pathway) to elicit growth and cell proliferation.

Question 3

What could potentially cause uncontrolled cellular prolif?

Answer 3

genetic mutations in any of the signaling proteins (tyrosine kinase, monomeric G protein Ras, etc)

Question 4

Genes that could potentially cause transformation are called?

Answer 4

proto-oncogenes

Question 5

Mutated versions of proto-oncogenes that cause cancer are called?

Answer 5

Oncogenes (eg, src, ras, myc, abl, etc.)

Question 6

An RNA tumor virus is…

Answer 6

a certain cancer causing retrovirus

Question 7

Cancer causing retroviruses (RNA tumor virus) contain…

Answer 7

viral oncogenes derived from host cell genome and cause virus-induced cancers upon infection

Question 8

The antigens of ________ cause tumors that have no cellular counterparts. Egs are:

Answer 8

DNA Tumor Viruses

eg; papiloma virus, adenovirus, polyomavirus

Question 9

DNA tumor virus antigens bind and inhibit proteins encoded by

Answer 9

tumor suppresor genes

Question 10

Tumor suppressor genes are responsible for…

Answer 10

cell cycle check points and prevent cells containing DNA lesions from completing the cell cycle

Question 11

Cells with irreparable DNA damage are triggered into…

Answer 11

programmed cell death (apoptosis)

Question 12

What protein triggers apoptosis?

Answer 12

p53 and others

Question 13

Some genes are proapoptotic:

Answer 13

Bad, Bix

Question 14

Genes that are anti-apoptotic:

Answer 14

Bcl2, Bcl-XL

Question 15

For cancer to occur, what must happen?

Answer 15

multiple lesions in the DNA must occur resulting in the activation of oncogenes and inactivation of tumor suppressor genes

Question 16

Overexpression of what genes could also cause cancer?

Answer 16

Bcl2- anti-apoptotic genes

Question 17

Cancer chemo agents and non-chemo agents are aimed at:

Answer 17

1) Preventing cellular proliferation and causing cell death by disrupting DNA metabolism.
2) Cause direct DNA damage resulting in mutations, DNA strand scission, DNA cross linking or indirectly inhibition, disruption of DNA biosynthesis

Question 18

What do the M phase disruptors do?

Answer 18

they interfere with tubulin polymerization/ deopolymerization and disrupt mitotic spindle fxn.

Question 19

How does retinoic acid work?

Answer 19

Cuases cancer cells to terminally differentiate and thus lose their ability to prolif.

Question 20

Cancer chemo agents are under two categories:

Answer 20

1) Cell-cycle specific agents (CCS)

2) Cell cycle non-specific agents (CCNS)

Question 21

Resistance to cancer chemo drugs is due to:

Answer 21

single gene mutations, gene amplification or by expression of multi-drug resistance surface membrane P-glycoprotein encoded by MDR1.

Question 22

What increases resistance to drugs by functioning as drug export pumps?

Answer 22

MDR1- MDR9

Question 23

Many cancer cells show chromosomal aberrations such as:

Answer 23

translocation (CML, Burkitt’s lymphoma)

Question 24

Cancer occurs in what three stages?

Answer 24

1) Initiation- DNA damaging agents cause initiation
2) Promotion- cellular events that promote deregulated growth and cell division
3) Progression- cellular proliferation cancer stem cells

Question 25

Agents that cause cancer are:

Answer 25

1) Heritable cancer- Ataxia, HNPCC, Breast
2) Exposure to ionizing radiation causing DNA strand scission
3) Exposure to UV radiation causes thymine dimer formation
4) Chemical carcinogens- DNA mutagenizing chemicals such as alkylating agents (benzopyrenes in cigarette smoke)
5) Certain chronic viral infxns (HPV, EBV, HBV, HBC, HTLV, Herpes-8- Kaposi’s sarcoma)