Exam 1 - Ch. 12 Flashcards
(116 cards)
Cancer
Is not a tumor
Is an abnormal growth resulting from uncontrolled
proliferation; it serves no physiologic function.
Benign tumors
Non-cancerous
Are named according to the tissues from which they
arise and include the suffix, -oma
Malignant tumors
Cancerous tumors
Are named according to the tissues from which they arise
Carcinoma in situ (CIS)
Are preinvasive epithelial malignant tumors of glandular
or squamous origin
Have not broken through the basement membrane or
invaded the surrounding stroma
Are not malignant
Point mutations
Small scale changes
Driver mutations
“Drive” progression of cancer
Passenger mutations
Random events
Gene amplification
Repeated duplication of chromosome → 10s or 100s of gene copies
Chromosome translocation
Large changes in chromosome structure
Piece of one chromosome is translocated to another chromosome
Oncogene
Mutant gene that would normally direct protein synthesis and cellular growth - contributes to the development of a cancer
Clonal proliferation (expansion)
Cancer cell progeny can accumulate faster than nonmutant neighbors. It acquires selective advantage over its neighbors
→↑ growth rate or ↓ apoptosis
Malignant transformation
Is the process during which a normal cell becomes a cancer cell
T OR F: Cancer cells are heterogeneous
TRUE
Cancer heterogeneity: due to proliferation and mutation
Proto-oncogenes
Normal nonmutant genes that code for cellular growth
Tumor-suppressor genes
Encode proteins that normally negatively regulate proliferation
anti-oncogenes
Activation of proto-oncogenes
hyperactivity of oncogenes
Mutation
loss or inactivity of tumor-suppressor genes
overexpression of products that prevent apoptosis, thus allowing continued growth of tumors
Growth factor signaling in cancer - Receptors
RAS
PI3K
MYC
D cyclins
Are oncoproteins that are activated by mutations in various cancers
retinoblastomaprotein(Rb)
RB is mutated in childhood retinoblastoma, and in many lung, breast, and bone cancers.
Mutation in the TP53 gene (tumor-suppressor gene)
“P53 protein is the guardian of the genome”
It monitors intracellular signals related to stress and
activates caretaker genes.
Mutation → Suppression of normal apoptosis.
Caretaker genes
Maintain genomic integrity.
• Encode proteins that are involved in DNA repair:
• errors in DNA replication
• mutations caused by UVR or ionizing radiation
mutations caused by chemicals and drugs.
Genomic Instability
- Loss of function of caretaker genes.
- Epigenetic silencing or modulation of gene function.
- Gene expression networks can be regulated by changes in miRNAs (miRs) and ncRNAs.
Oncomirs
miRs that stimulate cancer development and progression. miRs ↓ the stability and expression of other genes by pairing with mRNA.
BRCA1 and BRCA2
tumor-suppressors and caretaker genes that repair double-stranded DNA breaks