Neoplasia 2 Definitions Flashcards
T (14, 18) Translocation is most likely a … ?
follicular B-cell lymphomas have a t(14;18) translocation that fuses the BCL2 gene from chromosome 18 with the active IgH locus on chromosome 14 resulting in overproduction of anti-apoptotic BCL2
Describe a lymphoma
Follicular lymphoma usually presents with painless, generalized, very slowly progressive enlargement of lymph nodes at an average age of 60. It is equally common in men and women, but twice as common in whites as blacks and Asians
What is the best treatment of Lymphomas according to nichols ?
None
Why do lymphomas grow really slow ?
Lymphocytes are subjected to apoptosis at a slow rate and the resulting decrease in apoptosis causes a very slow accumulation of excess lymphocytes over many years
What normally inhibits angiogenesis ?
thrombospondin-1 (induced by p53) and destruction of HIF-1alpha (by VHL)
How does hypoxia induce angiogenesis ?
Tumoral hypoxia calls off VHL, so that HIF-1alpha starts VEGF production and growth of irregular leaky blood vessels, a process mediated by VEGF.
What is the angiogenic switch ?
The conversion from the normal “make-no-new-vessels” to the “OK-full-steam-ahead-make-new-blood-vessels” milieu is called the angiogenic switch
What actually happens in the angiogenic switch ?
The angiogenic switch is mediated by HIF-1alpha, basic FGF, loss of p53, decreased thrombomodulin-1, and overcoming anti-angiogenic factors (angiostatin, endostatin, vasculostatin).
What is an anti-VEGF agent ?
bevacizumab
What are the 4 steps of malignancy ?
(1) detachment of tumor cells from each other, (2) degradation of basement membrane and extracellular matrix, (3) attachment of tumor cells to basement membrane, and (4) migration of the escaped malignant cells through the interstitium.
How do tumor cells detach from each other ?
Detachment of tumor cells from each other is mediated in part by down-regulation of E-cadherin or mutated catenin.
How do tumor cells degrade the basement membrane ?
Degradation of basement membrane (type IV collagen) and extracellular matrix by performed by matrix metalloproteinases (especially MMP-9).
What mediates attachment of tumor cells to the basement membrane ?
Attachment of tumor cells to exposed basement membrane components is mediated by laminin and fibronectin receptors.
How do tumor cells migrate through the basement membrane and the extracellular matrix ?
Migration through basement membrane and extracellular matrix is mediated by binding to various factors such as autocrine motility factor
What is the metastasis pattern of colon cancer ?
Colon cancer typically metastasizes to local lymph nodes and then liver
What is the metastasis pattern of prostate cancer
prostate and breast cancers typically metastasize to local lymph nodes and then bone
What determines the area a tumor will typically metastasize to ?
haracteristic patterns are due to a combination of drainage pathways and organ tropism
How does organ trophism determine metastasizing patterns ?
The mechanisms of metastatic organ tropism include differential concentration of endothelial cell ligands for adhesion molecules in different organs and chemokines such as CXCR4 and CCR7 receptors in the case of breast cancer.
What is tumor embolus ?
Tumor cells that invade veins generally pass through the right heart and go to lungs, where they stop and elicit formation of blood clot around them
What happens to the blood clots that are formed in a tumor embolus ? What is the end result of a tumor embolus ?
Fibroblasts organize the blood clot part of this. The obstruction of small pulmonary blood vessels can eventually lead to pulmonary hypertension and right heart failure.
What are the classes of chemical carcinogens ?
Chemicals that cause cancer can be categorized as initiators or promoters, and direct or indirect.
What do initiators do ?
Initiators cause mutations, which become irreversible in the progeny of the mutated cell, if not reversed
After a mutation is initiated what does a promoter do ?
Promoters cause reversible proliferation of initiated cells.
What are direct carcinogens ?
Direct chemical carcinogens are few, generally reactive electrophiles
What are indirect carcinogens ?
Indirect chemical carcinogens require metabolic activation of procarcinogens commonly by cytochrome P450-dependent mono-oxygenases
What are common general carcinogens
Chemical carcinogens include estrogen, alcohol, anti-cancer drugs, asbestos, polycyclic and heterocyclic aromatic hydrocarbons, aromatic amines, amides, azo dyes and many other substance