Cancer Genetics

• Most cancerous cells develop due to damage to specific genes
• Some types of cancer have are heritable
• One normal copy of a gene (dominant allele)
• One damaged copy of a gene (recessive allele)
• Normal copy gets damaged
• Cell is now abnormal
• Other types of cancer are spontaneously derived

Characteristics of Cancer Cells

• Have lost contact inhibition
• Leads to abnormal cell divisions
• Have lost their normal function
• No longer product their specific products
• Undergo mitosis much more rapidly than normal cells
• Out compete normal tissue for space and resources
• Together these traits lead to “transformation”
• Cancerous cells spend more time in cell division than performing other duties
• This rapid cell division results in errors in DNA replication and normal chromosome segregation
• Result in aneuploid cells or cells with chromosome rearrangements
• Cancer cells can affect surrounding cells by sending them signals telling them to divide
• The resulting cell mass is a tumor
• Benign tumor do not affect function of surrounding tissues
• Malignant tumors impair normal organ function
• Tumors somehow cause increased vascularization, robbing surrounding tissue of nutrients

• Metastasis
• Spreading of cancerous cells to other parts of the body
• Caused by cells that enter the blood or lymphatic system
• Also caused by cell-to-cell communication
• Signals from cancerous cells affect distant cells
• Treatment takes advantage of rapid cell division of cancerous cells
• Chemotherapy drugs disrupt mitosis
• Radiation is more affective at killing cells in active cell division than cells in interphase

Terminology

· Carcinogen = Compound that tends to lead to transformation of normal cells

· Teratogen = Compound that causes birth defects

· Mutagen = Compound that causes damage to DNA