Cancer
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The human body has approximately 10^14 cells and around how many cell types?
200 There are about 100 cancer types that can arise from these cells.
Cancer results when a cell acquires genetic changes that allow it to proliferate due to the breakdown of what mechanisms?
Regulatory mechanisms This can result from mutations in cellular genes or the introduction of new genes by viruses.
A tumor is defined as an abnormal proliferation of what?
Cells Tumors can be benign or malignant.
What type of tumor remains confined and does not spread to other tissues?
Benign tumor Malignant tumors can invade surrounding tissues and metastasize.
What type of tumor is usually referred to as cancer?
Malignant tumor Malignant tumors can invade surrounding normal tissue.
What percentage of all tumors are classified as carcinomas?
90% Carcinomas arise from epithelial cells.
What are the three steps in tumor development?
• Initiation • Progression • Selection Each step involves genetic changes and selection of cells based on their abilities.
In cancer development, initiation refers to what?
Genetic alteration leading to abnormal proliferation of a single cell This is the first step in tumor development.
What do cancer cells lack that allows them to continue dividing under conditions that stop normal cells?
• Density-dependent inhibition • Contact inhibition These properties contribute to uncontrolled growth.
Cancer cells can secrete proteases and growth factors that lead to the formation of what?
New blood vessels (angiogenesis) This process supplies cancer cells with oxygen and nutrients.
What are substances that cause cancer called?
Carcinogens Examples include radiation, chemicals, and viruses.
What type of genes control cell proliferation, differentiation, and survival, and when mutated become oncogenes?
Proto-oncogenes Oncogenes promote uncontrolled cell growth.
What type of mutations do tumor suppressor genes typically undergo?
Loss of function mutations These mutations are often recessive and can be inheritable.
The two-hit hypothesis is associated with which cancer-related gene?
Rb (retinoblastoma gene) It requires mutations on both alleles for cancer development.
What is the most common target of mutation in human cancers, playing a role in approximately 50% of all cancers?
p53 This gene is crucial for regulating the cell cycle and apoptosis.
What is a key step in the Akt pathway that responds to growth factors leading to cell survival and proliferation?
Phosphorylation of PIP2 to PIP3 by PI 3-kinase PTEN is a phosphatase that balances this activity.
What is a common approach in cancer treatment that involves identifying mutated genes for early detection?
Genetic testing This helps in monitoring individuals with inherited susceptibilities.
What type of therapy involves genetically engineered T cells that can recognize specific proteins in cancer cells?
CAR-T cell therapy A chimeric antigen receptor (CAR) is introduced into a patient’s T-cell by viral infection.