Cancer 1 Flashcards
What causes cancer?
1) Failure of genetic mechanisms that control proliferation (replication) and growth.
2) Replication errors.
3) Physical and chemical agents.
4) Inherited genetic background.
What’s the difference between primary tumor and secondary tumor?
Primary cancer is defined as the original site (organ or tissue) where cancer began. In contrast, a second or secondary cancer may be defined in a few ways; as either a new primary cancer in another region of the body or as metastasis (spread) of the original primary cancer to another region of the body.
What’s the difference between carcinoma and sarcoma?
Carcinoma is the tumor which happens in the epithelial or endothelial cells (e.g. skin) while sarcoma is the tumor which happens in blood and muscles.
What’re the common properties of cancer cells?
1) Sustain proliferating signaling.
2) Evading growth suppressors.
3) Activating invasion and metastasis.
4) Enabling replicative immortality.
5) Inducing angiogenesis (production of new blood vessels).
6) Resisting cell death.
What do alterations cause by mutations affect?
They affect growth factors receptors and signal transduction genes, cell cycle regulatory genes, DNA repair genes, or genes controlling apoptosis (cell death).
How can we detect tumor and tumor cell morphology?
By histological examination (microscopic) and karyotyping where it may show gross chromosomal abnormalities.
What does microscopic examination of cancer cells show?
It shows abnormal location and morphology, loss of structural features characteristic of differentiated cell, and an abnormally large nucleus and prominent nulceoli.
What’s metastasis?
Malignant tumor cells acquire the ability to metastasize. To do so they must degrade the basement membranes of connective tissue underlying epithelial cells and surrounding the endothelial cells of blood vessels.
How can malignant tumors degrade the basement membranes?
By secretion of plasminogen activator, which activates the blood protease, plasmin.
Where does cancer typically originate?
It originates in dividing cells such as precursor (progenitor) stem cells and somatic cells.
What is the key feature that stem cells possess needed for malignancy?
The ability to continue to divide indefinitely.
What is the mutated gene called?
The mutated gene is called an oncogene or a tumor-suppressor gene.
What does the multi-hit model for cancer induction prove?
It proves that cancer happens due to cumulation of mutations of a cell. Model (I) shows that by getting older the person becomes more prone to different type s of cancer. Model (II) shows that cumulation of mutated genes increases the chance of cancer rather than the mutated genes being alone.
