Gene expression and Cancer + Ecoli Lab

Overview of Gene Expression and Cancer

  • Connection between gene expression and the development of cancer.

  • Emphasis on tumor suppressor genes and proto-oncogenes.

Tumor Suppressor Genes

  • Function: Regulate the cell cycle and prevent unchecked cell growth.

  • Act like brakes in a car—essential for regulating mitosis.

  • Example: p53 Gene

    • Highly studied tumor suppressor gene.

    • Mutated in over 50% of all cancer types.

    • Encodes a transcription factor that plays a critical role in cell cycle regulation, DNA repair, and apoptosis.

Proto-Oncogenes

  • Function: Promote cell growth and division when activated.

  • Example: RAS Gene

    • Codes for RAS protein, involved in intracellular signaling.

    • When activated by a growth factor, initiates a cascade that leads to transcription factor activation, driving the cell into S phase.

  • Mutations in proto-oncogenes can lead to overactivation.

    • E.g., mutated RAS protein can continuously signal for cell division, bypassing normal regulatory mechanisms.

Oncogenes and the Cell Cycle

  • Activation of oncogenes can lead to aberrant cell growth and survival.

  • Example: MYC Gene

    • Mutations result in increased cell activity and survival.

    • Bypasses cell cycle checkpoints, leading to uncontrolled growth.

Mechanisms of Tumor Suppressor Genes

  • p53 responds to DNA damage by:

    • Inducing cell cycle arrest through p21, inhibiting CDK and cyclins.

    • Allowing for DNA repair or triggering apoptosis if repair is not possible.

Consequences of Tumor Suppressor Gene Inactivation

  • Inactivation allows mutated cells to bypass checkpoints.

  • Leads to unchecked proliferation of damaged or abnormal cells.

  • Summary of genetic changes in cancer:

    • Inactivation of tumor suppressor genes

    • Activation of oncogenes

Upcoming Lab Activity

  • Expectation: Streak E. Coli on a plate for growth observation.

  • Control setup: E. Coli without antibiotics to allow growth.

    • Purpose: Determine transformation efficiency on Thursday by introducing plasmid containing glowing gene and antibiotic resistance.

  • Lab Safety Recommendations:

    • Bring a ponytail holder for long hair.

    • Wear goggles throughout the experiment.

Lab Report

  • A lab report will be required for this experiment as it is the last one of the year.