The Cell Cycle and Cancer

• 1. Cell growth checkpoint - occurs towards the end of growth phase 1 (G1), checks whether the cell is big enough and has made the proper proteins for the synthesis phase. If not, the cell goes through a resting period.
• 1. DNA synthesis checkpoint - occurs during the synthesis phase (S), checks whether dna has been replicated correctly, if so, cell continues to mitosis
• 1. Mitosis checkpoint - occurs during mitosis phase (M),checks whether mitosis is complete, if so, cell divides and cycle repeats
• Apoptosis - Cells change and break down so they can be removed by the immune system, occurs when cells are old or damaged or if a mistake occurs during any cell cycle phases, when apoptosis  doesn’t occur when it should, leads to cellular issues including cancerous cells
• Cancer: unchecked, rapid cell division - apoptosis does not take place when it should, error in DNA of cell, causing it to not go through the cell cycle checkpoint properly, prevents cell from staying in interphase for normal time period, It enters mitosis more quickly and often, reproduces very fast producing more cells with similar errors
• Mutations: a change in DNA - permanent changes in DNA structure are called mutations, when DNA is replicated in the S phase of the cell cycle, mistakes can occur, leading to mutations, which is passed through in mitosis, Mutations can be genetic or random or cause by external factors
• Tumours -  mass of cells caused by uncontrolled growth and division that forms a lump
• Benign Tumour (non cancerous) - do not affect surrounding cells or spread to neighboring tissue. Issue is when a benign tumour is crowding.
• Malignant (cancerous) - Have physically different looking cells and can affect or destroy surrounding cells
• Metastasis - cancer cells break away from original tumour and move to different parts of the body, wherever they settle and grow, a new tumour will form, this is called metastasis
• Normal cells - cells communicate, cannot normally divide in isolation, cells adhere to each other, have nucleus and nucleolus, can differentiate into different types of cells
• Cancer cells - don’t communicate, can reproduce in isolation, cells do not adhere to each other, have multiple nuclei and nucleolus, the ability to dislodge or metastasize, cannot differentiate, cannot carry out functions of a normal cell
• 1. Genetic predisposition in some types of cancers  - make you more likely to get cancer, no guarantee 

  2. Exposure to environmental factors - Carcinogens are environmental factors known to cause cancer (Tobacco smoke, radiation), some cancers may have hereditary and environmental factors
• Types of Treatment

  • Surgery
  • Chemotherapy
  • Radiations
  • Hormone therapy (drug treatment that regulates hormones in your body that could be leading to cancer cell growth)
  • Immunotherapy (various treatments that improve your immune system to help your own body systems kill off cancer cells)
• Surgery - physical removal of the cancerous tissue, if tumour is easily accessible, patient’s health many prevent this option
• Chemotherapy - Class of drugs that work by slowing or stopping cancer cells, can cause: hair loss, nausea, fatigue, attacks tumours too small to be detected
• Radiation - beams of light energy directed at the tumour, minimal side effects, susceptible to ionizing radiation because the DNA of many of the daughter cells is damaged preventing them from continuing to divide