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Oncology > Immunology and genetics of cancer > Flashcards

Immunology and genetics of cancer Flashcards

1
Q

Process of gene expression?

A
  • Trasnsciption (DNA to RNA) and translation (RNA to proteins)
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2
Q

4 bases of DNA? RNA?

A
  • adenine
  • thymine (in mRNA Uracil)
  • guanine
  • cytosine
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3
Q

What is MELAS syndrome?

A
  • arginine deficiency
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4
Q

Cell differentiation correlation with specialized cells? What are stem cells?

A
  • cell diff occurs as cells proliferate to form tissues
  • cell diff correlates with loss of ability to proliferate; highly specialized cells are terminally differentiated (nerve, muscle and cardiac cells)
  • terminally diff cells have finite life span, and are replaced with new cells produced from stem cells
  • stem cells: capable of self-renewal, cells divide w/o undergoing terminal differentiation
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5
Q

What controls cell cycle?

A
  • signal transduction
  • growth factors bind to surface receptors on cell, transmembrane proteins relay signals into cell
  • 2 types of growth factors:
    growth factors stim. cell division
    growth inhibiting factors - inhibit cell division
  • So healthy cells divide only when growth factor and growth inhibiting factor balance favors cell division
  • cancer cells divide w/o constraint (mutations in growth and growth-inhibiting factor genes)
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6
Q

Cell cycle phases?

A
  • G0: resting phase, cell has left cycle and has stopped dividing
  • G1: (interphase - G1, S, G2) cell increases in size, G1 checkpt ensures everything is ready for DNA synthesis
  • S: DNA replication
  • G2: cell continues to grow, G2 checkpt ensures that everything is ready to enter the M phase and divide
  • M: mitosis (prophase, metaphase, anaphase, telophase), cell growth stops at this stage and cellular energy is focused on orderly divison into 2 daughter cells, a checkpt in middle of mitosis ensures the cell is ready to complete cell division
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7
Q

Cancer cells contain what?

A
  • cancer cells contain genetically altered DNA

- can be hereditary/germline or somatic/spontaneous (somatic could be due to radiation)

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8
Q
  • 2 categories of cancer genes?
A
  • dominant: proto-oncogenes: gain of fxn mutations - altered or unregulated activity of these genes lead to tumorigenesis
  • recessive: tumor suppressor, loss of fxn mutations, loss of activity of tumor suppressors results in unregultaed pathways and tumorigenesis
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9
Q

What are the hallmakrs of cancer? (How can cancer be successful?)

A
  • self-sufficiency in growth signals
  • insensitivity to anti-growth signals
  • evading apoptosis and immune survelliance
  • limitless reproductive potential
  • capacity to invade other tissues
  • sustained angiogenesis
  • tissue invasion and mets
  • genomic instability
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10
Q

Ways that cancer cells invade?

A
  • resisting apoptosis
  • CSCs forming resistant phenotypes
  • epithelial mesenchymal transitions
  • interactions with microenviro
  • invadopodia and aquaporins ( invadopodia: actin rich protrusion of plasma membrane assoc with degradation of extracellular matrix in cancer invasiveness and mets - allows for penetration through membranes that typically restrict spread)
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11
Q

What does stage 4 cancer mean?

A
  • spread to other organs (into circulatory system)
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12
Q

Molecular basis of cancer - how is cancer stimulated?

A
  • mutations: from radiation, chemicals and viruses
  • loss of restriction of oncogenes (overactivity mutation) and decrease in tumor suppressor genes(underactivity mutation) - this leads to unregulated cell growth
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13
Q

Diff in overactivity and underactivity mutation?

A
  • overactivity (gain of fxn): just needs single mutation to become oncogene this goes on to activate mutation which enables oncogene to stim cell proliferation
  • underactivity (loss of fxn): one mutation event that inactivates tumor suppressor gene and then you need a second muation event to inactivate the 2nd gene copy - these 2 mutations fxnlly eliminate the tumor suppressor gene, stimulating cell proliferation
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14
Q

How do proto-oncogenes usually fxn?

A
  • they are normal cell proteins that have potential to cause cancer when mutated
    but
  • normally they are assoc with cell growth, cell division, and cell differentiation
  • they can be cell surface receptors, adapter molecules, and enzymes (kinases/phosphatases)
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15
Q

Cancer types?

A
  • body part where cancer originates
  • type of cell that tumor originated from:
    carcinoma - epithelial cells
    sarcoma - CT cells
    lymphoma and leukemia
    germ cell tumors: testicle and ovary
    blastomas: immature cells or embryonic tissue
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16
Q

Diff b/t hereditary and nonhereditary retinoblastoma?

A
  • so in a normal healthy individual: you have 2 good Rb genes, one may inactivate but you would still have no tumor
  • heridatary Rb: inherited mutant Rb gene gives rise to more mutant gene copies, occasionally one will inactivate good Rb gene this then leads to excessive cell proliferation - retinoblastoma (***Most people with inherited mutation will develop a tumor)
  • nonhereditary Rb: occassionally a cell inactivates one of its 2 good Rb genes and then very rarely 2nd copy could be inactivated in the same line of cells - this then would lead to excessive cell proliferation and retinoblastoma
    result: only 1/30,000 normal people develop tumor
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17
Q

Methods of ID cancer critical genes?

A
  • assay for oncogenic effects
  • study of rare syndromes- tumor suppressors
  • candidate genes
  • genomics: exhaustive surveying is feasible, ID every change in tumor cell vs. normal
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18
Q

Steps of carinogenesis?

A
  • normal change to mutatnt through initiation and then mutant - divides through promotion and progresses into overgrowth of mutant (neoplastic) cells
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19
Q

Components of progression?

A
    1. primary tumor growth
    1. local/regional spread
    1. distant spread
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20
Q

Steps of invasion and mets of cancerous growth?

A
  • cancer cells start to replicate
  • they then invade surrounding tissues and blood vessels
  • they are transported by circulatory system to distant sites
  • cancer cells reinvade and grow at new location
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21
Q

Progression of normal cells to malignant cells?

A
  • have normal epithelium - dysplasia occurs (considered mutation)
  • this then leads to pre malignant tissue (carcinoma in situ) and then turns maligant (invasive cancer)
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22
Q

What is leukoplakia of the oral cavity?

A
  • pre-malignant squamous mucosal change
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23
Q

What does cancer need to grow? How is this made possible?

A
  • cancer cells grow into a clump and will need its own blood supply
  • certain growth factors that cancer cells can make to force the body to grow cancer cell’s blood supply
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24
Q

Process of metastasis on cellular level?

A

1 - clonal expansion, growth diversification and angiogenesis
2 - met subclone, this then adheres to and invades basement membrane
3 - passes through ECM
4 - leads to intravastion (invading blood vessel)
5 - this leads to interaction with host lymphoid cells and a tumor cell embolus forms
6 - this then adheres to basement membrane of vessel and leads to extravasation and becomes a metastatic deposit - angiogenesis occurs and with that growth

25
Q

How do mets occur?

A
  • spread to organs through blood stream
  • spread to organs through lymphatic fluid system
  • seeding into spaces in the body ( pleural, peritoneal and pericardial spaces)
26
Q

Mets of primary breast cancer?

A
  • regional nodes: axilla, internal mammary
  • bone
  • liver
  • lung
  • brain
  • peritoneal, pleural, CSF
27
Q

Mets of primary lung cancer?

A
  • regional nodes: hilar, mediastinal, supra-clav
  • bone
  • liver
  • lung
  • brain
  • peritoneal, pleural, CSF
28
Q

Mets of primary colorectal cancer?

A
  • regional nodes: pelvic and mesenteric
  • liver and lungs ***
  • peritoneal, pleural and CSF
29
Q

Mets of primary prostate cancer?

A
  • regional nodes: pelvic
  • bone***
  • brain
30
Q

Mets of primary melanoma?

A
  • regional nodes
  • bone
  • liver
  • lungs
  • brain
  • peritoneal, pleural, CSF
31
Q

Mets of primary brain cancer?

A
  • stays in brain, CSF
32
Q

Why are some cancers much more aggressive than others?

A
  • b/c of ploidy
  • normal cells have 23 pairs of x’somes = 46 - diploid
  • cancer cell = can have less or more than 46 = aneuploid (instead of diploid (2 sets of xsomes - total of 4 )) - can have total 3, 5, 2, 6 if aneuploid
  • the higher number of x’somes the more likely the cells will become malignant
33
Q

Grading of tumors? 1

A

1
diff: well
charateristics: looks like tissue of origin, makes cell proteins like original tissue
growth rate: slow, close to normal cell divisions
(really hard to tx with rad/chemo) - needs to be excised

34
Q

Grading of tumors? 2

A

2
diff: moderately
characteristics: has many features like tissue of origin, less organized
growth rate: faster, see occasional mitoses

35
Q

Grading of tumors? 3

A

3
diff: poorly diff
characteristics: has few features of tissue of origin, very little real organization
growth rate: see more mitoses (actively dividing)
- very active - more likely to respond to therapy initially

36
Q

grading of tumors? 4

A

4
diff: completely undiff, anaplastic
characteristics: has no features to help distinguish its origin
growth rate: see many mitoses throughout the tissue

  • most responsive to therapy initially
37
Q

General relationship b/t tumor grade and prognosis?

A
  • low grade has higher pt survival rate (75% compared to high grade 25%)
38
Q

Old cancer model of cancer stem cell theory?

A

1) all tumor cells can form new tumors and are therefore equally tumorigenic
2) unregulated growth is due to serial acquisition of genetic events leading to expression of genes that promote cell proliferation with concomitant silencing of growth inhibitory genes and blunting of cell death
3) cancer is proliferative disease

39
Q

New cancer model of cancer stem cell theory?

A

1) tumors arise from cells termed cancer stem cells that have properties of normal stem cells, particularly self-renewal and multipotent (minority) of tumor cells
2) unregulated cell growth is due to disruption in regulatory mechanism in stem cell renewal
3) cancer is a stem cell disorder and not a simple mechanism whereby cell proliferation is disrupted

40
Q

Why are so many cancers so difficult to tx?

A
  • b/c stem cells persist in tumors as a distinct pop that likely causes relapses and mets
  • can tx at first with traditional therapy and then the cancers reoccur (ovarian, and breast cancer have increased mortality after so many years b/c of massive recurrence)
    even if these cancers are responding to traditional therapy - there is still the mutated stem cell pop
  • Stem cell therapy - could be the answer for cancer cure - b/c it kills the stem cells (this should halt tumor’s growth)
41
Q

What cells does chemo attack? Hopes of stem cell therapies?

A
  • chemo: kills differentiated or undifferentiated cells, which form bulk of tumor but are unable to generate new one, a pop of cancer stem cells which gave rise to it, remains untouched and may cause relapse of the disease
  • the development of specific therapies targeted at stem cells holds hope for improvement of survival and quality of life of cancer pts, esp for those with mets
42
Q

What are cancer stem cells?

A
  • cells that have properties of normal stem cells
    1) abilities to self-renew
    2) ability to diff into multiple cell types
    3) they form a distinct pop in tumors that likely causes disease relapse and mets
43
Q

What are the cancer risks in people with HNPCC?

A
  • colorectal - 78%
  • endometrial - 43%
  • stomach - 19%
  • biliary tract - 18%
  • urinary tract - 10%
  • ovarian - 9%
44
Q

What would you want to do if you have a female pt that presents with 2 month hx of increasing mass in right breast

  • mammogram revealed 3 cm R breast mass
  • hx pertinent for extensive family hx of cancer
  • What is your next step?
A
  • bx (this reveals poorly diff adenocarcinoma)
  • should have BRCA 1&2 test done: refer to genetic counselor
  • will go on to have surgery and aggressive chemo
  • can have lumpectomy + radiation or mastectomy
45
Q

Sporadic vs hereditary cancers?

A
  • Hereditary: inherit one damaged gene - more likely to divide into another damaged gene - this leads to tumor
  • sporadic: 2 normal genes, one may mutate and then again, another may mutate, not as likely to happen as if it was inherited - once 2 genes mutated - leads to cancer
46
Q

How common are hereditary cancers?

A
  • 7-10% of breast or ovarian cnacer
  • 9-11% of colorectal cancer
  • smaller % of renal, thyroid, endometrial, pancreatic cancer
  • most cancers are sporadic
  • even hereditary cancers are multifactorial (involve both genetic and enviro factors)
47
Q

Patterns of hereditary cancers?

A
  • more cancer (of related type) in a family than expected by chance alone
  • vertical transmission w/in a family
  • early ages of onset
  • multiple primary cancers in one individual
48
Q

Common hereditary cancer syndromes?

A
  • hereditary breast/ovarian cancer syndrome:
    breast, ovarian, male breast, prostate, pancreatic
    caused by mutations to BRCA1 or BRCA2 genes
  • lynch (HNPCC) syndrome: colon, gastric, endometrial, ovarian small bowel, pancreas, brain
    caused by mutations to MLH1 ( 80% chance of getting colon cancer), MSH2 (30% chance) , MSH6, PMS1, PMS2 genes
  • Familial adenomatous polyposis syndrome: colon, stomach, thyroid, brain, liver, adrenal gland, caused by mutations to APC or MYH genes
49
Q

What is lynch syndrome?

A
  • mutations to 5 diff genes (genetic heterogeneity) - MLH1, MSH2, MSH6, PMS1, PMS2
  • mismatch repair genes: maintain DNA integrity during DNA replication: often leads to microsatellite instability in tumors
  • malignancies may include colon, stomach, uterine, small bowel, ovarian, ureters, kidney
  • penetrance up to 80%
50
Q

Prophylactic surgery options for HNPCC assoc mutation carriers?

A
  • options include subtotal colectomy, hysterectomy, and oophorectomy
  • surgery doesn’t eliminate cancer risk!
  • expert panel made no recommendation for or against surgery due to unproven efficacy
51
Q

Does survelliance reduce risk of colorectal cancer in HNPCC families?

A
  • yes
    11. 9% compared to 4.5%
    (3: 1 difference)
52
Q

Surveillance options for pts of HNPCC assoc mutations?

A
  • colorectal cancer: colonoscopy begining at 20-25, repeat q 1-2 yrs
  • endometrial cancer:
    transvaginal US and endometrial aspirate annaully starting 25-35
53
Q

Less common hereditary cancer syndromes - Li Fraumeni syndrome?

A
  • P53 gene

- breast, bone, leukemia, brain, soft tissue sarcomas

54
Q

Less common hereditary cancer syndromes - Cowden syndrome?

A
  • PTEN gene

- breast, uterine, thyroid, ovarian, colon cancers

55
Q

Less common hereditary cancer syndromes- Peutz-Jeghers syndrome?

A
  • STK11 gene
  • colon, small bowel, breast, ovarian, pancreatic cancers
    (have small brown lesions in oral mucosa early on)
56
Q

Less common hereditary cancer syndromes - xeroderma pigmentosa syndrome?

A
  • XP3 gene

- basal cell, squamous cell and melanoma

57
Q

Less common hereditary cancer syndromes - Von Hippel-Lindau syndrome?

A
  • VHL gene

- brain, retina, kidney, pancreas, adrenal gland cancers

58
Q

Less common hereditary cancer syndromes - MEN-1 syndrome?

A
  • MEN1 gene

- pancreas, pituitary, parathyroid, thyroid

Oncology (11 decks)

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