Topic 3.4 - Cancer cell biology and CAL 3

bladder to liver cancer metastasis example - steps (5)

1. Cells of epithelium proliferate to form benign tumour within the epithelium

2. Cells become invasive, breaking through the basal lamina into the tissue and entering a nearby capillary

3. Cells travel through the bloodstream and adhere to blood vessel walls elsewhere

4. Cells escape from the blood vessels and form micro metastasis

5. Cells colonize liver, forming a full blown metastasis

are invasive cells more likely to cross into a capillary or a lymphatic vessel

wall of a lymphatic vessel that ultimately discharges its content into the blood stream

tumour cells often pass through lymph nodes leading to lymph node metastasis

hanahan and weinberg hallmarks of cancer - summary

lists essential requirements a cell needs to achieve or perform to success as a cancer cell

hallmarks of cancer - textbook’s summary (5)

1. Altered homeostasis that results in cells growing and dividing at a faster rate than they die

2. Bypass of normal limits to cell proliferation

3. Evasion of cell death signals

4. Altered cellular metabolism

5. Manipulation of tissue environment to support cell survival to evade a deleterious immune response

accumulation of mutations leading up to tumorigenesis

Cell progressively acquires a set of multiple mutations that eventually lead to the development of cancer

When cell accumulates enough malignant capabilities, it survives and proliferates -> proliferation is unchecked and progeny outcompete others

accumulation of mutations leading up to tumorigenesis - example steps (4)

1. One cell initially obtains a mutation that leads to excessive proliferation

2. Cell obtains a second mutation which further enhances proliferative capacity of the cell and tis progeny

3. Third mutation occurs in a clone of this cell which leads to ability of cell to invade nearby tissues and thus metastasize

4. Progeny of this cell becomes the dominant clone in the tumour

what two factors contribute to tumorigenesis

icnreased cell division

decreased apoptosis

impact of activating mutation in Ras pathway

continuous activation of the signal

causes inappropriate promotion of cell cycle entry → cell no longer proliferates when it receives an extracellular signal but instead is constantly primed to enter S phase

tumour suppressor genes

prevent proliferation and act in recessive manner

two inactivating mutations or epigenetic changes needed to eliminate TSG

oncogenes

promote proliferation and act in dominant manner

single gain of function mutation in a single copy of the cancer-critical gene can drive cell towards cancer

BrdU/ EdU - purpose

shows levels nuclei of cells in S phase -> dark nuclear staining indicates proliferating cells

Flow cytometry - purpose

to analyse cell cycle distribution in MDCK-Mock and MDCK-snail cells under basal conditions and then after mitogen exposure

western blot - purpose

to compare levels or protein states

eg. G1 checkpoint molecules -> cdk inhibitors, p21 and p27, and Rb phosphorylation

immunohistochemistry - purpose

shows where protein is located in tissue

in situ hybridisation - purpose

shows where mRNA is located in tissue

counterstain vs specific signal

Counterstain = used to reveal tissue or cellular structure -> where cells and tissue are organised

Specific signal = indicates molecule being studied -> what the experiment is testing

• Only the specific signal should be used to answer the question