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University of Toronto Scarborough
Biological Sciences
Aarti Ashok

Lecture 23 J Cancer N There are as many cancers as there are cell types in our bodies The Phenotype of Cancer Cells N Cancer cells have many different types of abnormalities 1. Lost important controls over cell growth: (d) J NO contact inhibition**** a. Spread on pteri dish, form a monolayer (single layers of cells) b. Layer of cells make contact with each other. If cel next to them, they will stop growing c. Respect boundaries = contact inhibition d. Inhibited upon contact with neighbouring cells e. Tumour cells have lost this ability, they no longer have this contact inhibition phenotype f. Although they can also form monlayer, they can grow on top of each other and form foci structure (little foci, little clumps of cells that can grow on top of each other that lost this contact inhibition) g. Figure 16.4 J difference in normal cells and cancer cells i. Dotted blue line: growth of normal cells in the absence of any growth factors (proteins supplied in medium that we grow cells in, positive signal for them to divide because you have a lot of stuff) J absence: they will barely survive ii. Solid blue line: will survive, over time graph will plateau bc those growth factors are used up, unless you replenish the culture medium, growth factors are gradually used up until they die off iii. Cancer cells }L[ 7Z}L[ }ZZL }L2}Z }Z]L order to replicate and survive iv. Provide with growth factors, extra incentive to grwo better v. Solid and dotted red line does not vary, neither of the lines ARE NOT PLATEAUING (like blue lines) J }L[Z}L}ZL LZL } 2}Z }7L]][Z2]LL]L2}2Z 2. They can be immortal and readily grow on soft agar a. Agar = cleaned plastic plates b. Plastic good surface for cells to stand on c. Cells produce cell adhesion molecules, lay down matrix protein on plastic surface to provide them something to grip onto d. Normal cells not grow on soft agar = nothing to hold onto e. Cancer cells accumulate mutations give them ability to cling onto soft surfaces f. }L[ ] , LZ]}wn stably, additional proteins use to bind to soft surfaces g. Small tumour is isolated, we can spread it out on soft agar and look for growth 3. They have a larger number of chromosomal defects often as a result of their inability to repair DNA: a. Mutated several proteins that would normally help them fix DNA damage because of exposure or toxin created during replication b. Normally, mismatch would be corrected
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