well differentiated (how well cancer cells resemble regular cells)
low mitotic index
Characteristics of a malignant tumor?
high mitotic index
One of the first characteristics of a cancer cell is sustained proliferative signaling. Describe this process
Normally a growth factor would bind to a receptor and result in cell replication. In a cancer cell there is a mutation where this is signaling of a cell replication without the ligand.
This is described as a mutant gene that in their nonmutant state directs protein synthesis and cellular growth.
Oncogenes - "good guy turned bad"
What is a tumor suppressor gene?
Encodes proteins that in their normal state negatively regulate proliferation.
Also called anti-oncogenes
What is the term for a normal, nonmutant gene that codes for cellular growth?
T/F: One of the hallmarks of cancer cells is to evade growth suppressors.
What are the growth suppressors that are active in normal cells?
1) TP53 - receives inputs from stress and abnormality sensors from within the cell's intracellular operating systems and leads to apoptosis.
2) RB (retinoblastoma-associated protein) transduces growth inhibitory signals that originate largely outside of the cell. Stops cell from going to S phase.
What is the intrinsic protein that causes cell apoptosis normally?
P53. activated in a number of ways including chemotherapy and radiotherapy which cause DNA damage.
How do cancer cells enable replicative immortality?
By activating telomerase.
Telomeres are protective caps on each chromosome and usually become smaller and smaller with each cell divison. In cancer they somehow activate telomerase and limitations of mitosis are not a problem anymore.
True or False. Inducing Angiogenesis is a hallmark of cancer.
Examples of activators include: VEGF-A, B, C, FGF1, FGF2
Examples of inhibitors: thrombospondin 1,2, interferon alpha and beta, angiostatin, endostatin, collage IV fragments
How do cancer cells activate Invasion and Metastasis?
1) Localized invasion - the tumor is formed and grows slowly toward capillary
2) Intravasation - cancer cells fit through the endothelial lining of blood vessels and circulate throughout body
3) Extravasation - while circulating it fits through the endothelial lining of blood vessels into sometype of organ/tissue
4) Formation of micrometastasis
5) Colonization - formation of macrometastasis
True or False. All cancers have a certain amount of inheritability.
False. Only some cancers are inheritable.
Name some internal factors that cause the formation of cancer cells.
mutation of tumor-suppressor genes
loss of herozygosity
Epigenetic changes - DNA regulation change, NOT sequence change. ex: histone defect
How does inflammation (external factor) play a role in causing the formation of cancer cells.
-Cytokine release from inflammatory cells.
-Promotion of mutations
-Decreased response to DNA damage
What are some external causes (other than inflammation) of cancer formation?
1) Chemicals : carcinogen
2) Viruses: Hep. B & C, Epstein-Barr virus, Kaposi sarcoma herpesvirus, HPV, Human T-cell leukemia-lymphoma virus