Cancer

Question 1

According to Hannahan and Weinberg 2000, what are the 6 hallmarks of cancer cells?

Answer 1

• Evading Apoptosis
• Self sufficiency in growth signals
• Insensitivity to anti-growth signals
• Sustained Angiogenesis
• Tissue Invasion and Metastasis
• Limitless replicative potential

Question 2

According to Hannahan and Weinberg 2011, what are the 4 additional hallmarks of cancer (on top of the original 6?)

Answer 2

• Deregulating Cellular Energetics
• Genome Instability and mutation
• Avoiding Immune destruction
• Tumor propagating inflammation

Question 3

Explain growth signal activity in normal, non cancer cells

Answer 3

Normal cells require growth signals transmitted into the cell via transmembrane receptors that bind distinctive classes of signalling molecule. Cannot proliferate without this.

Question 4

Define apoptosis

Answer 4

Cell death from ‘old age’ of the cell. Natural process and part of the lifecycle of cells and cell turnover

Question 5

What are the steps of apoptosis?

Answer 5

• Cell membrane disrupted and cytoplasmic/nuclear skeletons broken down
• Chromosomes degraded and nucleus fragmented
• Cell corpse engulfed by nearby cells

Question 6

What are the two categories of apoptotic ‘machinery’?

Answer 6

-Effectors and Sensors
Sensors: monitoring extra/intracellular environment for conditions that influence whether a cell should die or not
-Effectors: the things that actually cause the death of the cell

Question 7

How do cancer cells avoid apoptosis?

Answer 7

• Loss of proaptotic regulators

Question 8

What is the replicative potential of normal cells?

Answer 8

40-70 doublings, due to the Hayflick Limit, and the progressive loss of telomeres

Question 9

How do cancer cells develop limitless replicative potential?

Answer 9

• Impaired senescence through disabled pRb and p53 tumor suppressor
• Maintenance of telomeres by upregulation of telomerase which adds more telomers, keeping it above the critical amount to cause cell death

Question 10

What is an oncogene?

Answer 10

A gene which can transform cell into a tumor cell if mutated

Question 11

How may exercise impact cancer risk by impacting cancer cell angiogenesis?

Answer 11

Increase angiogenesis beyond that which is required for the cell to survive in order to improve access to the cell by drugs or immune cells

Question 12

What are the two categories of mechanisms protecting us from cancer?

Answer 12

• Limiting exposure to factors promoting tumor initiation and progression (Non-Immune)
• Targeting pre-cancerous or tumour cells if they have developed (Immune)

Question 13

What are the proposed anti-cancer mechanisms induced by physical activity?

Answer 13

• Better protection against free radicals by enzymatic antioxidants
• Better DNA repair
• Lower insulin and lower IGF-1
• Increased IGFBP-3
• Increased gene expression for tumor suppressors
• Reduced exposure to testosterone due to increases in sex-hormone binding globulin
• Decreased exposure to oestrogen
• Improved immune function
• Lower inflammation
• “weight loss” or body composition improvement
• Decreased GI transit time and reduced exposure to carcinogens

Question 14

Summarise the findings of Rundqvist et al 2013

Answer 14

Physical activity reduces the risk of cancer by reducing levels of growth stimulating factors (EGF, Epidermal Growth Factor), and increases the levels of growth inhibitory factors (IGFBP-3)

Question 15

Summarise the design of Rundqvist et al 2013

Answer 15

Blood samples taken at rest pre exercise, and 120 minutes after 1 hour of moderate intensity exercise in 10 healthy males with mean age 25

Question 16

Summarise the findings of McTiernan et al 2005

Answer 16

Physical activity reduces the risk of cancer by decreasing IGF-1 and increasing IGFBP-3

Question 17

Summarise the findings of Song et al 2012

Answer 17

Physical activity reduces the risk of cancer by increasing gastro-intestinal transit time so the gut is in contact with potential carcinogens for less time

Question 18

Summarise the findings of Pederson et al 2016

Answer 18

Physical Activity reduces the risk of cancer by stimulatign the immune system to detect and eliminate pre-cancerous or cancerous cells if they form

Question 19

Summarise the findings of Dethlefson et al 2016

Answer 19

Physical activity reduces the risk of cancer by stimulating a production of anti-inflammatory cytokines and other exercise-associate factors (E.g. adrenaline)

Question 20

Summarise the findings of Dethlefon et al 2017

Answer 20

Physical activity reduces the risk of cancer because adrenaline released during exercise can directly target cancer cells (or pre-cancer cells) inhibiting their growth.