Lecture Set 22

Question 1

What are the different types of cancer classifications?

Answer 1

3 general types –> carcinomas (cancer from epithelial cells = most common), leukemias (bloodstream/circulating cells), lymphomas (solid mass, hematopoietic cells), and sarcomas (cancer from muscle or connective tissue)

from there, there are more specific terms to refine the location of the cancer. Ex. adenoma = benign tumour in epithelial cells of the glands, a malignant tumour in the epithelial cells of the glands = adenocarcinoma

Question 2

Define tumour, benign, and malignant

Answer 2

tumour = clone of cells that proliferate and accumulate regardless of normal restraints
benign = single localized mass, only become problematic if they are large enough to inhibit normal function or if there is excessive secretion of biologically active substance
malignant = cells that can invade surround tissues (metastasize)

Question 3

How do tumours form?

Answer 3

increased cell division, decreased cell apoptosis
results from a mutation in a single cell. Not just a single mutation, a large accumulation of mutations, which is why age is the best correlation with cancer rates

Question 4

Describe how epithelial cells normally divide

Answer 4

only the basal cell layer divides, one cell remains a stem cell, one differentiates, however, mutation can lead to multiple stem cells that continue to divide.
In intraepithelial neoplasia, as it goes from low to high grade, start to see more and more of the epithelium show proliferation and less morphological differentiation. tumour metastasizes when it breaks through the basal lamina into the connective tissue

Question 5

Describe some of the hallmarks of cancer

Answer 5

evasion of apoptosis
ability to invade and metastasize
induce angiogenesis
self sufficiency in growth signals
insensitive to antigrowth signals
limitless replication

Question 6

What are the two types of changes that cancer cells undergo?

Answer 6

genetic = change in DNA sequence
epigentic = change in gene expression

Question 7

What are the causes of cancer mutations

Answer 7

radiation, chemicals, infectious agents, heredity

Question 8

What are the different types of cancer-critical genes?

Answer 8

1) gain of function mutations –> dominant, growth-promoting effect
2) loss of function mutations –> tumor suppressor genes, recessive (requires mutation in both copies) (ex. retinoblastoma gene)
3) indirect genomic instability –> DNA caretaker genes, results in genomic instability

Question 9

What are the 5 ways to convert proto-oncogenes to oncogenes

Answer 9

chromosomal translocation = chromosomal segments move from one chromosome to another
local DNA rearrangement = inversion, transposition, addition, deletion
insertional mutagenesis
point mutations –> change in single base pair, common with Ras oncogenes leading to oncoprotein, leads to constitutively active Ras
Gene amplification = multiple gene copies leading to overproduction of protein