Flashcards in Neoplasia III #7 (2/1/16) Deck (25):
______ is the prototypic anti-apoptosis gene.
What does overexertion of BCL2 protein cause?
It protects cells form apoptosis, allowing them to survive for prolonged periods. Results in steady accumulation of cells often seen in low grade lymphomas.
Tumors cannot grow larger than 1-2mm in diameter, unless ____________.
they are vascularized (nutrients and oxygen)
What provides tumors access to vasculature?
Angiogenesis facilitated metastases
T or F, only certain subclasses may be capable of metastasizing?
What are the 2 major phases of Invasion and Metastasis?
1. Invasion of the extracellular matrix
2. Vascular dissemination and adhesion/homing of tumor cells.
What are steps of Invasion of the Extracellular matrix?
1. Tumor cells detach from each other
2. Attach to ECM components (BM and CT) inculding collagens, glycoproteins and proteoglycans.
3. Degrade matrix components
Where are tumor cells vulnerable?
when in circulation
Tumor metastasis is a function of _____ and _____.
Site and vascular/lymphatic drainage
What are 3 conditions that involve unstable DNA?
1. Hereditary nonpolyposis colon Ca Syndrome: mismatch repair defect, increase in MSI.
2. Xeroderma pigmentosum: increase skin cancers, inability to repair UV damage.
3. Bloom syndrome: ataxia telangiectasia, fanconi anemia, familial breast cancers, fragile DNA diseases.
T or F, No single mutation results in cancer.
True, cancers usually exhibit multiple genetic alterations ..
Overtime tumors can become more aggressive, why?
Probably due to acquisition of multiple mutations during tumor growth, resulting in numerous "subclones" with different characteristics such as drug resistance, resistance to hypoxia....Basically natural selection in a malignant lesion.
What 3 types of Karyotypic changes in tumors?
Balanced translocations = extremely common, especially in hematopoietic neoplasms (often between chromosome 22 and 9)
Deletions = rentinoblastoma (Rb), colon and oral Ca.
Gene Amplifications = neuroblastoma and breast cancers.
What are the 3 major factor that are associated with genetic damage?
_____ chemicals require no chemical transformation to be carcinogenic.
Most chemicals are ______.
Indirect carcinogens = only become active after metabolic conversion, also called "Procarcinogens"
What do chemical "promoters" do?
Enhance the actions of carcinogens, but have little inherent mutagenicity.
What are some sources of Radiation carcinogenesis?
- ultraviolet light
- Gamma radiation from nuclear fission
What are 2 types of Viral oncogenesis?
1. RNA oncogenic viruses: Human T-ce;; leukeia Virus type 1
2. DNA oncogenic viruses: HPV and cervical Ca, EBV and burkitt lymphoma.
What factor aid in tumor immunity?
Tumor Antigens = tumor specific antigens and tumor associated antigens .
Anti tumor Effector Mechanisms = Cytotoxic T cells (CD8+). natural killer cells, Macrophages, humoral factors.
Immunosurveillance = Strongest argument is increased frequency of cancer observed in immunocompromised.
How can a tumor "evade" the immune system?
- Selection of antigen negative variants
- Reduced expression of HLA antigens
- Lack of T cell co-stimulation - sensitization requires 2nd signal together with foreign antigen
What are the 5 clinical features of Neoplasia?
1. Location - adjacent to vital stuructures?
2. Functional activity - hormone synthesis
3. Ulceration - bleeding secondary infection
4. Cachexia - progressive wasting state
5.Paraneoplastic syndromes (10-15% of Ca pts): Hypercalcemia, Cushing's syndrome, paraneoplastic pemphigus.
What is Grading?
Refers to an estimate of the aggressiveness of a cancer based microscopic appearance.
What is staging?
Describes cancer extent: size of primary lesion, lymph node involvement, and metastatic spread as estimated by clinical exam and imaging.