Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Tissues > T28 - Carcinogenesis II > Flashcards

T28 - Carcinogenesis II Flashcards

1
Q

What are the three categories of physical agents that play a role in carcinogenesis?

A

chemical carcinogens

radiant energy

microbial agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is immune surveillance?

A

immune system’s surveilling the body for premalignant and malignant cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two subdivisions of chemical carcinogens?

A

direct-acting agents

indirect-acting agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the difference between direct-acting and indirect-acting agents in chemical carcinogens.

A

direct-acting agents require no prior metabolic conversion = weak carcinogens

indirect-acting agents erquire metabolic conversion (e.g. hydrocarbons in fossil fuels or benzo-a-pyrene in cigarette smoke)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the relationship between indirect chemical agents and cancer susceptibility?

A

because indirect agents require metabolic activation, enzymatic pathways involved in activation can impact cancer susceptibility (e.g. everyone inherits different cytP450 enzymes, so different susceptibilities to cancer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is aflatoxin B1?

A

DNA mutagen produced by strains of Aspergillus flavus in improperly stored grains and nuts (i.e. peanuts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Aflatoxin B1 causes

A

hepatocellular carcinoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is carcinogenicity commonly tested?

A

expose a rodent to the carcinogen and then monitor for tumor onset and growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the mechanism of action for chemical carcinogens?

A

contain highly-reactive electrophiles that bind to DNA and cause mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two types of radiation carcinogens?

A

ionizing radiation

UV rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Ionizing radiation has what effect on DNA?

A

causes chromosomal breakage and aberrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Give a historical example of ionizing radiation that led to increased cancer prevalence.

A

Chernobyl nuclear disaster led to higher rates of thyroid cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do UV rays affect DNA?

A

induce formation of pyrimidine dimers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give an example of a tumor that results from UV ray damage of DNA.

A

melanomas (skin cancers in general)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the only retrovirus that has been definitively shown to be directly carcinogenic?

A

HTLV-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

HTLV-1 is endemic to (2)

A

the Caribbean

Japan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

HTLV-1 causes

A

T-cell leukemia, because it has a tropism for CD4+ T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Explain on a cellular level how HTLV-1 causes T-cell leukemia. (4)

A

HTLV-1 genome encodes TAX viral protein → TAX activates cytokine genes and associated receptors in T cells → autocrine and paracrine loops cause T cells to proliferate → polyclonol process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give an example of an oncogenic RNA virus.

A

HTLV-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Give four examples of oncogenic DNA viruses.

A

Epstein-Barr virus

human papilloma virus (HPV)

hepatitis B virus (HBV)

hepatitis C virus (HCV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Epstein-Barr virus has been implicated in the pathogenesis of what human tumors? (4)

A

Burkitt lymphoma

B-cell lymphomas in AIDS patients

Hodgkin lymphoma

nasopharyngeal carcinoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain, on a cellular leve, how the Epstein-Barr virus contributes to tumor pathogenesis. (2)

A

EBV gene products stimulate B-cell proliferation

EBV binds to and infects B cells through CD21, a type 2 complement receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a gross consequence of HPV?

A

benign squamous papillomas (warts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the low risk subtypes of HPV? (2)

A

HPV-6

HPV-11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the high risk HPV subtypes? (2)

A

HPV-16

HPV-18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The oncogenic potential of HPV originates from what genes?

A

viral genes E6 and E7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the roles of viral genes E6 and E7 in HPV oncogenesis.

A

E6 binds to and mediates degradation of p53

E7 binds to and mediates degradation of RB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the properties of hepatitis B virus (HBV)? (3)

A

does not directly make the cancer-causing genes (unlike HTLV)

associated with liver cancer due to inflammation

continued proliferation caused by HBV causes DNA damage and gene mutations that are oncogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the transcription factor associated with HBV?

A

HBV encodes transcription factor HBx, which can activate TGFb1 and IGF1 growth factors and inhibit p53

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

(T/F) HCV is a DNA virus.

A

False. Hepatitis C virus is not a DNA virus (it’s an RNA virus), but like HBV is strongly linked to liver cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are heliobacter pylori and where are they found?

A

gram-negative bacteria that reside between mucus layer of stomach and gastric epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Why is heliobacter pylori unique in the context of carcinogenesis?

A

first bacterial organism to be classified as a carcinogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

H. pylori is responsible for causing what two tumors?

A

gastric adenocarcinoma

gastric lymphoma

34
Q

What are the clinical symptoms of gastric adenocarcinoma caused by H. pylori?

A

chronic inflammation of gastric epithelium (i.e. chronic gastritis)

35
Q

H. pylori-related lymphomas have what cellular origin?

A

B-cell origin

36
Q

The B-cells implicated in H. pylori-induced gastric lymphoma reside where?

A

reside in marginal zones of gastric lymphoid follicles → hence the name MALT lymphomas

37
Q

How does the H. pylori-induced infection of B cells lead to neoplastic transformation?

A

chronic inflammation and stimulation of marginal zone B cells leads to DNA damage and neoplastic transformation

38
Q

How is MALT lymphoma treated?

A

assuming early detection, can be treated with antibiotics to cure H. pylori infection

39
Q

Differentiate between tumor specific and tumor associated antigens.

A

tumor specific antigens are only found on tumor cells

tumor associated antigens are found on tumor cells and on some normal cells

40
Q

What are oncofetal antigens?

A

antigens expressed during embryogenesis but disappear and are not normally expressed in adult tissues

41
Q

Give two examples of oncofetal antigens.

A

carcinoembryonic antigen (CEA)

alpha-fetoprotein (AFP)

42
Q

What is carcinoembryonic antigen?

A

luminal glycoprotein involved in cell adhesion

43
Q

Carcinoembryonic antigen is associated with what malignancies? (2)

A

inflammatory and cancerous lesions of both the colon and pancreas

44
Q

What is the clinical utility of the carcinoembryonic antigen?

A

because of its lack of specificity for cancer, it’s most useful for monitoring recurrence of carcinomas after surgery

45
Q

What is alpha-fetoprotein?

A

glycoprotein globulin secreted by fetal liver and yolk sac

46
Q

Alpha-fetoprotein is associated with what malignancies?

A

alpha-fetoprotein is expressed by:

hepatocellular carcinomas

testicular cancers/teratomas (i.e. germ cell tumors)

yolk sac tumors (i.e. endodermal sinus tumors)

47
Q

Give two examples of glycoproteins (apart from oncofetal antigens) that can serve as tumor antigens.

A

gangliosides

mucins

48
Q

Describe how gangliosides can serve as tumor antigens.

A

normal in composition, but overexpressed in melanomas and colon cancers

49
Q

Describe how mucins can serve as tumor antigens.

A

under-glycosylated

50
Q

As tumor antigens, mucin are associated with what malignancies? (4)

A

carcinomas:

breast

pancreatic

ovarian

colon

51
Q

Differentiate between mucin CA-125 and mucin CA-19-9.

A

CA-125: blood marker expressed in ovarian cancers, but NOT specific

CA-19-9: blood marker sensitive but NOT specific to pancreatic cancer

52
Q

How does Gleevec/Imatinib cure/treat CML?

A

it poisons the BCR-ABL fusion protein

53
Q

Give three examples of oncogenes that, when mutated, produce peptides only found in tumor cells.

A

p53

RAS

CDK4

54
Q

Give two examples of non-mutated proteins that can be overexpressed, conferring tumor immunity.

A

HER2/NEU (in breast cancer)

tyrosinase (in melanomas)

55
Q

What is Herceptin?

A

anti-HER2/NEU antibody

56
Q

What is the predominant anti-tumor mechanism?

A

cell-mediated immunity

57
Q

What are the four classes of anti-tumor immune effector mechanisms?

A

cytotoxic T cells

natural killer (NK) cells

macrophages

humoral mechanisms

58
Q

What is the role of cytotoxic T cells in antitumor effector mechanisms? (2)

A

protects against virus-associated neoplasms

requires prior exposure (i.e. immunization)

59
Q

What is the role of natural killer cells in antitumor effector mechanisms? (3)

A

kill without prior sensitization (in contrast to cytotoxic T cells)

activated by IL-2

active against tumor cells with low MHC Class I expression

60
Q

What is the role of macrophages in antitumor effector mechanisms? (2)

A

produce reactive oxygen species or TNF to kill tumor cells

61
Q

What is the role of humoral mechanisms (antibodies) in antitumor therapy?

A

monoclonal antibodies against tumor markers used in therapy (i.e. anti-CD20)

62
Q

Carcinogenesis obviously occurs in patients without immune deficiencies. What are three mechanisms by which tumors evade the host immune system?

A

selective outgrowth of antigens (disguise)

lost/reduced expression of histocompatibility molecules (hide)

spontaneous/pathogen/drug-induced immunosuppression of host (suppress)

63
Q

What are the local effects of tumors on hosts? (3)

A

destruction of normal tissues

ulceration through natural boundaries, causing hemorrhage or infection

tumor rupture or infarction

64
Q

Describe the hormonal effect of tumors on hosts. Give an example.

A

over-production of hormones native to tumor origin

for example:

insulinoma of pancreas

65
Q

What is cancer cachexia?

A

progressive loss of fat + muscle leading to wasting, weakness, and anemia

66
Q

What causes cancer cachexia?

A

caused by excess of cytokines, not just tumor metabolism

67
Q

Define paraneoplastic syndrome.

A

symptoms not accounted for by local or distant spread of tumor

68
Q

Give three examples of paraneoplastic syndromes.

A

endocrinopathies (lung tumor making ACTH)

neuromyopathies (lung tumor causing myasthenia gravis)

vascular/hematologic derangements (pancreatic carcinoma causing deep vein thrombosis)

69
Q

What are four tools used in the diagnosis of cancer?

A

pathology

tumor markers

molecular cancer diagnostics

molecular profiling

70
Q

What are the four substeps within pathology as a tool for the diagnosis of cancer?

A

histology

cytology

immunochemistry

flow cytometry

71
Q

What is histology, in the context of diagnosing cancer?

A

microscopic examination of formalin-fixed tissue using H&E staining

72
Q

What is cytology, in the context of diagnosing cancer?

A

microscopic examination of individual cells smeared on slide

73
Q

What are the two types of cytologic specimens?

A

exfoliative = removal of cells from tissue/organ

fine needle aspiration = use a needle + syringe to suck out cells

74
Q

What are two disadvantages of cytology?

A

limited specimen sample

no info about tissue architecture

75
Q

What is the utility of tumor markers in diagnosing cancer?

A

can be used to screen for malignancies or monitor for cancer relapse

76
Q

In what context is “minimal residual disease” detected?

A

PCR is used to detect presence of BCR-ABL transcripts in blood to monitor Philadelphia chromosome-positive CML

77
Q

Describe how molecular profiling of tumor works. (4)

A

mRNA extracted from 2 tissue sources (normal + tumor) → complementary DNA samples made → cDNA hybridized to cDNA probes in a matrix → laser detects fluorescence from each spot, allowing comparison of genome between normal + tumor

78
Q

Give three examples of techniques (and an associated malignancy) used in molecular cancer diagnostics.

A

flow cytometry = hematopoietic malignancies

FISH = CML

PCR = CML

79
Q

How does Epstein-Barr virus cause Burkett lymphoma? (4)

A

EBV stimulates B-cell proliferation → secondary mutations accumulate → t(8;14) chromosomal translocation → constitutive expression of Myc gene fused to immunoglobulin heavy chain gene

80
Q

(T/F) In HPV, E6 and E7 are sufficient to induce transformation.

A

False. RAS and other genes would be required to induce transformation — E6 or E7 on their own are not sufficient.

81
Q

What is hepatitis C virus’ mode of action? (2)

A

induction of cirrhosis and parenchymal regeneration

Tissues (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions