Oncology Flashcards
What is the only heritable cancer syndrome that has been described in domestic dogs?
Mutation in the BHD gene encoding folliculin (tumor suppressor gene) –> renal cystadenoma & dermatofibrosis
What is the pathomechanism of positron emission tomography in imaging cancer?
almost all tumor upregulate the glucose transporter (GLUT-1), making the cells efficient glucose scavengers –> give a radiolabeled analog of glucose (18F-fluorodeoxyglucose) –> allows imaging of tumor cells (when combined with CT scan)
What portion of the UV spectrum is most likely to be responsible for nonmelanotic skin lesions?
UVB – range of 280-320 nm
How can cumulative long-term exposure to UVB induce skin tumors?
1) Directly through genetic mutations - including mutations in p53, 2) Indirectly by impairing the response of the immune system to tumor antigens
What papillomavirus is associated with oral papillomas?
CPV-1
What papillomavirus is associated with cutaneous papillomas and cutaneous pigmented plaques?
CPV-2 and CPV-6
What IHC marker is used to identify papillomaviruses?
p16 protein
Describe the pathogenesis of papillomavirus infection
Virus gains entry to basal layer keratinocytes –> Virus undergoes dissambley and early (E) proteins enter the nulceus and produce copies of viral DNA –> forces the infected cells to divide –> as the cells progress to the surface, they express the late gene (L), which forms the capsid of the virus –> virus released into the sloughing epithelial cells
What portion of the papillomavirus is an oncoprotein?
E protein - prevent infected cells from leaving the cell cycle
What is the antigen used in the papillomavirus vaccine?
L1 capsid protein of CPV-1
What are the papillomaviruses reported in the cat?
FcaPV-1, -2, -3
What is the causative agent of feline sarcoid?
bovine papillomavirus (BPV-14)
How do the clinical lesions of papillomavirus differ in the cat compared to the dog?
Plaques in the cat (vs warts in the dog), usually affect haired skin
What papillomavirus is associated with bowenoid in situ carcinomas?
FcaPV-2
What are the histologic features of feline fibropapilloma?
similar to equine sarcoid - characteristic fibroblastic proliferation, hyperplasia of epidermis, and rete ridges
What are the two most important envelope proteins in FeLV?
P15E and GP70; P15E is a mediator of immunosuppression, GP70 is a glycoprotein that contains three subgroup antigens
Antibodies produced against what portion of the FeLV can be neutralizing and thereby prevent infection?
envelope proteins
What is P27? What virus is it associated with?
core protein (capsid) of FeLV - found in large amounts in the cytoplasm of cells and bodily fluids
What is the antigen of FeLV that is detected in IFA tests and ELISAs?
P27 (capsid protein)
Which virus is the LEAST susceptible to dessication: papillomavirus, FeLV, FIV?
Papillomavirus (non-enveloped)
Lymphomas in cats with FeLV are usually of what cell of origin: B or T cells?
T cells
What is the only subgroup of FeLV that is transmitted contagiously between cats?
subgroup A - subgroup B is created when subgroup A recombines with endogenous FeLV envelopes at sequences already in the feline genome; Subgroup C arises from a mutation of subgroup A
Cats that have Feline Sarcoma Virus always test positive for what other virus?
FeLV - FeSV results from the recombination of FeLV DNA provirus with cat proto-oncogenes
T/F: Natural transmission of Feline Sarcoma Virus between cats has not been described.
TRUE
What age of cat is more commonly affected by Feline Sarcoma Virus-induced tumors?
young cats
T/F: Feline Immunodeficiency Virus is oncogenic.
False - it is immunosuppressive and can affect normal immunosurveillance of neoplastic cells
What is interphase?
period of doubling of the genetic material of the cell (composed of G1, S, and G2)
What are the four phases of the cell cycle?
M phase, G1, S phase, and G2
What are the four phases of the M phase?
prophase, metaphase, anaphase, telophase
What is the role of cyclin-dependent kinases in the cell cycle?
mediate progression through the cell cycle; are enzymes that catalyze the addition of phosphate groups onto target substrates involved in DNA replication, protein synthesis, and cell division
What is the role of p53 in the cell cycle?
negative regulator of the cell cycle - cell damage triggers p53 to either cause cell cycle arrest or apoptosis
What are proto-oncogenes? Examples?
key genes involved in the control of cell growth and proliferation, mutations can lead to malignancy; growth factors, growth factor receptors, protein kinases, signal transducers, nuclear proteins and transcription factors
How do mutations in proto-oncogenes lead to cancer?
“gas pedal” - allows cycle to continue without check
How do mutations in tumor suppressor genes lead to cancer?
“brakes” - normal function is to inhibit growth and proliferation, without tumor suppressor genes, cell cycle can continue unchecked
What are the top four tumor types of the skin and subcutaneous tissues in cats?
basal cell tumors, mast cell tumors, squamous cell carcinoma, fibrosarcoma
What effect does the viral protein E7 (papillomavirus) have on the cell cycle?
inhibition of pRB (tumor suppressor gene) –> proliferation
What effect does the viral protein E6 (papillomavirus) have on the cell cycle?
destabilizes p53 (tumor suppressor gene) –> proliferation
Papillomavirus’ disruption of p53 can lead to increased levels of what protein that is detectable with IHC?
p16
Cytological appearance of basal cell tumors
inflammatory cells, squamous cells, sebaceous epithelial cells, melanin, melanophages, fibroblasts, mast cells
What is the clinical presentation of basal cell carcinoma in dogs?
plaques or nodules, often darkly pigmented
Differences between squamous cell carcinoma in situ and actinic keratosis
SCC in situ can occur on both haired and unhaired skin (in areas w/ and w/o sun exposure); Actinic keratosis occurs in lightly haired skin with UV exposure, typically accompanied by solar elastosis and fibrosis of the skin
What cat breeds are at DECREASED risk of SCC?
Siamese, Himalayan, Persian
What breeds are at INCREASED risk for trichoblastoma?
poodles and setters
Histological characteristics of trichoblastoma
differentiation to the hair germ of developing hair follicle
Histological characteristics of trichoepithelioma
differentiation to all segments of the hair follicle; dermal in origin but can extend into subcutis
What is the most common malignant tumor of the ear canal in both dogs and cats?
ceruminous gland adenocarcinoma
What breeds are at INCREASED risk for ceruminous gland adenocarcinoma of the ear canal?
Cocker spaniels and GSD
What is acrometastasis?
lung-digit syndrome – common in cats with primary pulmonary carcinomas
