Neoplasia Flashcards
Xeroderma Pigmentosum
Inherited disorder of DNA repair
Leads to increased risk of cancers of skin following UV exposure
UV radiation causes cross-linking of pyrimidine residues preventing normal DNA replication
DNA damage repaired by nucleotide excision repair system in normal individuals-an inherited loss of one leads to XP
Hereditary nonpolyposis Colon Cancer
Autosomal Dominant
Characterized by familial carcinomas of the colon affecting the cecum and proximal colon
Defects in the genes encoding a proteins that work together to carry out DNA mismatch repair
Errors accumulate throughout the genome and can activate proto-onocogenes or inactivate tumor suppressor genes
Microsatellites are tandem repeats of six nucleotides that are unstable and incrase or decrease the length of tumor cells
Mutations in MSH2 and MLH1 associated with HNPCC
TGF-B receptor, TCF component of B-catenin pathway and BAX are all affected
Ataxia Telangiectasia
Gene mutated in ATM is important in recognizing and responding to DNA damage by ionizing radiation
Gait abnormalities, vascular malformations, immunodeficiency
Increased susceptibility to sinus and pulmonary infections
Decreased IgG and IgA
Hypoplastic thymus
Bloom syndrome
Predisposition to very broad spectrum of tumors
Defective gene encodes a helicase that participates in DNA repair by homologous recombination
developmental defects
Familial adenomatous polyposis
Adenomatous polyposis coli (APC) is a tumor suppressor that function by down regulating growth promoting signaling pathways
APC is a component of the Wnt signaling pathway which has a major role in controlling cell fate, adhesion, and cell polarity during embryonic development
APC protein holds B-catenin activity in check-APC degrades B-catenin in absence of Wnt singling
B catenin/TCF complex promotes growth of colonic epithelial cells by increasing the transcription of MYC, cyclin D1
Loss of APC leads to uncontrolled B-catenin leading to thousand of colon polyps taht can give rise to colon cancer
