● Mass of cells with unlimited potential to divide/grow and serves no useful function in the
body
● Rarely heritable, but genetic
Tumor - distinct mass of abnormal cells that do not have normal controls on cell division
Benign - do not invade surrounding tissue (remain localized)
Malignant - invade surrounding tissue
Metastatic - cancer cells spreada and establish secondary tumors in other sites
● Most cancers are sporadic and influenced by the environment
- Siblings are rarely affected by the same cancer
● Cancers also develop over time
- Changes in cancer rates due to new environment tend to take decades
- Incidence of cancer rises with age
High incidents of Cancer correlate with tissues that undergo more cell divisions (result of error in
replication)
Tumor suppressor genes:
- Normal gene prevents uncontrolled growth
- Abnormal gene - no inhibition - results in tumor if no normal allele is present
RB Gene: G1 to S transition
- Prevents E2F(transcription factor) gene from activating replication
- BRCA 1 and BRCA 2 are used to repair double strand breaks
Tumor Suppressor p53
- Function at g1 checkpoint
- Mutated form seen in diverse cancer types: colon, lung, breast, brain and 50% of human
tumors
- P53 delays cell division until damage is repaired or programs cell to die
Oncogenes
● Proto-oncogenes: promote cell division, but are activated to regulate properly
● Mutates to become oncogene (uncontrolled division)’
Most cancers are not due to defects in one gene, but accumulatins of several genes
Angiogenesis (growth of blood vessels) : important to tumor progression (may be inactivated or
underexpressed)
body
● Rarely heritable, but genetic
Tumor - distinct mass of abnormal cells that do not have normal controls on cell division
Benign - do not invade surrounding tissue (remain localized)
Malignant - invade surrounding tissue
Metastatic - cancer cells spreada and establish secondary tumors in other sites
● Most cancers are sporadic and influenced by the environment
- Siblings are rarely affected by the same cancer
● Cancers also develop over time
- Changes in cancer rates due to new environment tend to take decades
- Incidence of cancer rises with age
High incidents of Cancer correlate with tissues that undergo more cell divisions (result of error in
replication)
Tumor suppressor genes:
- Normal gene prevents uncontrolled growth
- Abnormal gene - no inhibition - results in tumor if no normal allele is present
RB Gene: G1 to S transition
- Prevents E2F(transcription factor) gene from activating replication
- BRCA 1 and BRCA 2 are used to repair double strand breaks
Tumor Suppressor p53
- Function at g1 checkpoint
- Mutated form seen in diverse cancer types: colon, lung, breast, brain and 50% of human
tumors
- P53 delays cell division until damage is repaired or programs cell to die
Oncogenes
● Proto-oncogenes: promote cell division, but are activated to regulate properly
● Mutates to become oncogene (uncontrolled division)’
Most cancers are not due to defects in one gene, but accumulatins of several genes
Angiogenesis (growth of blood vessels) : important to tumor progression (may be inactivated or
underexpressed)
