Chapter 5 - Neoplasia Flashcards
What is neoplasisa?
- “new growth”
- implies abnormality of cellular growth/tumor
What is malignant neoplasm?
- cancer
- associated with altered expression of cellular genes
- not always surviveable
True or false: benign growths are generally easily cured.
true
A ____ tumor has few mitosis, a slow growth rate, strictly local, no metastasis, rare tumor necrosis, rare recurrence, good prognosis.
benign
A ______ tumor is anaplastic with abnormal cell shape and size, has many mitoses, rapid growth rate, frequent metastases, common tumor necrosis, common recurrence.
malignant
What does this picture show?
- anaplastic tumor cells showing variation in cell size, shape, and large hyperchomatic nuclei
____ suffix indicates benign tumor (adenoma)
-oma
true or false: carcinoma and sarcoma are malignant tumors
true
What is the origin of a carcinoma?
epithelial (i.e. adenocarcinoma)
What is the origin of a sarcoma?
mesenchyma (i.e. nerve, bone, muscle)
What is the origin of leukemia?
white blood cells
Lymphomas, hepatomas, and melanomas are all (benign/malignant) forms of tumors.
malignant
How do you decipher between a benign and malignant tumor?
- asymmetry
- beningn = symmetrical
- malignant = asymmetrical
- border
- benign = even edges
- malignant = uneven edges
- colour
- benign = one shade
- malignant = two or more shades
- diameter
- benign= < 6 mm
- malignant = > 6 mm
_____ allows the malignant cells to ignore growth controlling signals
malignant phenotype
What is the 2nd leading cause of death in the U.S.?
cancer
___% of cancer deaths occur in individuals over age 55
77%
True or false: men have a 1 in 2 risk of developing cancer; women have a 1 in 3 risk.
true
What is the 5-year cancer survival rate?
68%
______ of cancer-related deaths may be attibutable to lifestyle factors (i.e. tobacco use, nutrition, obesity, sun exposure, sexual exposure to HPV)
1/3
What is the leading cause of cancer related death in men and women?
lung cancer
- worst survival rate
- death rate increased
- second-hand smoke increases risk
What are the two types of carcinogens found in tobacco smoke?
- initiator (genetic damage)
- promoter (promotes tumor growth)
Which 4 dietary factors are believed to be related to cancer risk?
- fat
- fiber
- alcohol
- antioxidants
What are the dietary suggestions with regards to reducing cancer risk?
- limit excessive calorie and alcohol intake
- increase dietary fiber, fruit and vegetables
What is a carcinogen?
potential cancer causing agent
What is a proto-oncogene?
- enhance growth-producing pathways
- normal cellular genes that can be transformed into oncogenes by activating (gain-of-function) mutations
What is an oncogene?
a proto-oncogene in its mutant overactive form
What is a tumor suppressor gene?
- inhibits cell proliferation
- cancers may arise when tumor suppresor gene function is lost or abnormally inhibited
What do gain-of-function mutations code for?
- growth factors
- receptors
- cytoplasmic signaling molecules
- nuclear transcription factors
What are growth factors (mitogens)?
manufactured peptides secreted into extracellular space –> diffuse to nearby cells –> interact with recepters on target surface –> activate signaling cascade –> produce autocrine signaling
What are growth factor receptors?
- transmembrane proteins
- mitogen-binding on area outside of cell
- enzyme-activating area on inside of cell
- binding activates cell proliferation
What happens when there is a mutation of growth factor receptors?
- expression of receptors that should not be there
- excessive amount of normal receptors
- receptors with abnormally high affinity
What are cytoplasmic signalling pathways?
- numerous enzymes and chemicals that transmit signals from receptors at cell surface to nucleus
- mutant proto-oncogene can activate pathway even when no signal is at the cell surface
- ras gene: mutations lead to cancer
- RAS protein stimulates growth in presence of GTP but turned on in malignant cells
- ras gene: mutations lead to cancer
What are transcription factors?
- proteins that must be assembled at the promoter area to begin gene transcription
- normally sequestered and prevented from discriminate activity until appropriate signals cause their release
- mutations cause overproduction of transcription factors which interfere with normal functions
- mvc gene: mutations lead to cancer
True or false: mutations in the ras and mcv genes can lead to cancer
true
When do proto-oncogenes become activated?
when mutations alter their activity so that prolifeation-promoting signals are generated inappropriately
What are the 4 general ways for proto-oncogenes activation?
- oncogenes introduced to host by retrovirus
- proto-oncogenes within cell suffers mutagenic event
- DNA sequence lost/damaged allowing oncogene to become abnormally active
- error in chromosome replication causes extra copies of proto -oncogene in genome
What is a retrovirus?
- composed of RNA
- contains reverse transcriptase enzyme
- direct synthesis of a DNA copy of viral RNA
- DNA copy incorporates into host cell DNA
- becomes part of host genome
______ comes from the HIV retrovirus
Kaposi’s sarcoma
______ comes from the epstein-barr virus
burkitt lymphoma
______ comes from human t-lymphocyte virus type 1
adult t-cell leukemia/lymphoma
What are tumor-suppressor genes?
- “BRAKE” to regulate cell growth and prevent mutations
- slow cell cycle
- inhibit proliferation of cells due to GFs (growth factors)
- stop proliferation if cells damaged
Rb, BRMRE, and APC tumor all compromise:
A) proto-oncogenes
B) oncogenes
C) tumor-supressor genes
D) none
C
What happens when tumor-suppressor genes are inactivated by mutations?
removes BRAKE on cell proliferation causing cell to proliferate uncontrollably
What is the Rb gene?
- “master brake” for cell cycle
- blocks/stops cell division
- binds TFs (transcription factors)
- inhibits factors from transcribing genes that initiate cell cycle
What happens when the Rb gene becomes inactivated?
- removes brake that stops cell division causing replication to occur
What is the p53 gene?
- most common tumor-suppressor gene
- normally inhibits cell cycling
- accumulates after DNA is damaged and binds to DNA to stall division to allow DNA to repair itself
- may direct cell to apoptosis
- mutated or damaged p53 allows genetically damaged/unstable cells to survive and continue to replicate
More than 1/2 of all types of human tumors lack functional ____.
p53
true or false: cancer cells that lack functional p53 may be resistant to chemotherapy/radiation
true
_____ and ____ are tumor suppressor genes associated with breast cancer.
BRCA1 and BRCA2
Which BRCA gene is associated with family history and increase risk of breast cancer?
BRCA1
What are the three steps involved in cancer development?
- initiation
- via inappropriately active proto-oncogenes or inactive tumor suppresor genes
- promotion
- stage during which mutant cell proliferates
- activation of oncogene
- inactivation of tumor suppressor gene
- nutritional factors
- infection
- stage during which mutant cell proliferates
- progression
- mutant cells exhibit malignant behaviouor
- laminin receptors
- lytic enzymes
- anchorage independent
- bizarre karyotype
- mutant cells exhibit malignant behaviouor
_____ carcinogens ar capable of initiating cell damage and promoting cellular proliferation
complete
_____ carcinogens are promoters that stimulate growth but are incapable of causing genetic mutations sufficient to signly initiate cancer
partial
How do cells become immortalized?
- telomerase
- telomeres cap the chromosomes
- advanced cancer cells activate telomerase to stabilize and protect the telomeres, keeping the chromosome from fragmenting
What is metastasis?
- process by which cancer cells escape their tissue of origin and initiate new colonies of cancer in distant sites
How do cancer cells spread?
circulatory or lympathic systems
______ help identify parent tissue of cancer origin
tumor markers
Which of the following are typically used as tumor markers:
A) Enzymes
B) Proteins
C) Carbohydrates
D) All of the above
A, B
What is angiogensis?
- process by which cancer tumor forms new blood vessels in order to grow
- does not develop until late stages
- triggers not understood
- inhibition of angiogenesis is important therapeutic goal
What is the system most widely used when grading & stagint tumors?
TNM
T=tumor
N=nodes involved
M=metastasis
What is cachexia?
- overall weightloss and weakness
- loss of appetite
- increased metabolic rate
- nausea/vomitting
- immune suppression
_______ contributes to anemia, leukopenia, and thrombocytopenia and is due to invasion and destruction of bone marrow, poor nutrition, annd chemotherapy
bone marrow suppression
______ is deficiency in circulating red blood cells.
anemia
What is leukopenia?
- deficiency in circulating white blood cells
- caused by malignant invasion of bone marrow via malnutrition and chemotherapy
- may cause suspension of chemotherapy treatment until WBC count reovers
What is thrombocytopenia?
- deficiency in circulating platelets
- important mediators in blood clotting
- predispose to hemorrhage if count is below 20,000
What are paraneoplastic syndromes?
- tumor production of hormones or cytokines
- hypercalcemia (excess calcium)
- cushing syndrome via ACTH secretion
- hyponatremia and water olverload due to ADH secretion (low sodium)
