Genetics #4
Genetics of Cancer:
● Cancer is considered a genetic disease
● Due to mutations in genes that control cell division and/or apoptosis, invasion
● Mutations are due to:
- Errors in DNA replication
- Deamination of C- mutation to T
- Environmental exposure
- Carcinogens (industrial, cigarette smoke)
● But no dramatic increase in cancer incidence- no cancer “epidemic”
● There's been a decrease in prostate cancer, but an increase in skin cancer and colon
cancer in younger people
● Largest influence on cancer rate is life style
- Tobacco and diet account for over 60%
● Classic example of lifestyle intervention: London chimney sweeps (Dr. Potts, 1775)
- Young boys who cleaned chimneys were getting testicular cancer
- Requiring them to wash off after cleaning decreased the rate of testicular cancer
among the chimney sweepers
● Many genes that contribute to cancer have effects on the cell cycle
● Oncogenes and tumor suppressor genes normally contribute to cell cycle
● Tumor suppressor genes: genes that control entry into G0
- Inactivated in cancers
- Considered recessive
● Oncogens: genes that promote entry into S cell division
- Expressed in cancers
- Considered dominant
Genetics of Cancer:
● Cancer is considered a genetic disease
● Due to mutations in genes that control cell division and/or apoptosis, invasion
● Mutations are due to:
- Errors in DNA replication
- Deamination of C- mutation to T
- Environmental exposure
- Carcinogens (industrial, cigarette smoke)
● But no dramatic increase in cancer incidence- no cancer “epidemic”
● There's been a decrease in prostate cancer, but an increase in skin cancer and colon
cancer in younger people
● Largest influence on cancer rate is life style
- Tobacco and diet account for over 60%
● Classic example of lifestyle intervention: London chimney sweeps (Dr. Potts, 1775)
- Young boys who cleaned chimneys were getting testicular cancer
- Requiring them to wash off after cleaning decreased the rate of testicular cancer
among the chimney sweepers
● Many genes that contribute to cancer have effects on the cell cycle
● Oncogenes and tumor suppressor genes normally contribute to cell cycle
● Tumor suppressor genes: genes that control entry into G0
- Inactivated in cancers
- Considered recessive
● Oncogens: genes that promote entry into S cell division
- Expressed in cancers
- Considered dominant
