Lecture 5 Flashcards Preview

Cancer and the cell cycle > Lecture 5 > Flashcards

Flashcards in Lecture 5 Deck (28):
1

What are the four most common features of the nuclear morphology of cancer cells?

  • Nucelar shape and magrin irregularities 
  • Changes to chromatin compaction/texture
  • Altered Nuclei
  • Variations ins size within a population (polymorphism)

2

What are the two main types of chromatin?

Heterochromatin- Highly compacted and generally inactive, found around the egde of the nucleus. Replicated in late S phase

Euchromatin - Less compacted and conatins active genes. Replicated in early S phase

3

How are chromatin loops formed?

scaffolding/matrix attachment regions (S/MARS) 

Create 100kb loops

4

What makes up the nuclear matrix?

Filamentous and granular network of proteins and RNA

5

What further level os the nuclear matrix has been hypothesised?

The tissue matrix

The matrix connects cells possibly allowing communication 

6

Molecular machines for what processes assemble on the nuclear matrix?

Transcription, splicing and DNA replication at the bases on chromatin loops

7

What protein is important for ensuring the correct spatial arrangement of genes in the nuclear matrix during transcription?

SATB1

8

Where will DNA replication occur?

At one of the immobolised sites on the nuclear matrix, spooling DNA through the machinery

9

Where are chromosomes found in the interphase nucleus?

As chromatid - but each would be chromatid has its own segregated area. But some do mingle for functional reasons 

10

Outline 3C chromatin conformation capture 

  1. Cross link chromatin with associated proteins 
  2. Digest away any chromatin not crosslinked
  3. Ligate together ends of chromatin 
  4. Analyse the pieces

11

What is Hi-C?

Uses sequenced product of 3C and whole genome map to map location of associated protein and chromatin in normal nucleus

12

What is 4C?

Look at interactions from Hi-C over time 

13

How can mingling between the chromatid cause translocation?

Double strand breaks that occur in areas of mingling may be repaired by fusing chromatid from two different chromosomes together

14

Outline an example translocation seen due to chromatid mingling 

BRC-ABL fusion 

BCR gene from chromosome 22 and ABL gene from chromosome 9

Creates a tyrosine kinase which is hyper activated - causing cell growth and proliferation. Seen in chronic myeloid leukemia 

 

15

What are balanced translocation associted with?

Leukemias and lymphomas - which can be cured by chemotherapy 

16

What are unbalanced rearrangements associated with?

Solid tumours - more disorganisation and more difficult to cure 

17

Give some examples unbalanced rearrangements 

  • Ploidy 
  • Variation in copy number
  • Inversion
  • Duplications 
  • Deletions 
  • Nonreciprocal translocations 

18

Which nuclear matrix protein has been implicated in unbalanced rearrangements?

High-mobility-group protein (HMGI) in prostate cancer

19

What two models exist to explain the order in the nucleus matrix?

Derministic model - Underlieing nuclear matrix gives rise to factories 

Self-organisation models- Factories form and recruits nuclear matrix proteins 

20

What controls whether cyclin E is soluble or associated with the nuclear matrix?

Differentiation state

Soluble in stem cell

Associated in differentiated cell

21

Where was cyclin E in cancer cell lines?

Soluble in nucleus - so no control 

22

What does having factors, such as cyclin E, associated with the nuclear matrix give normal cells?

An immobolising platform - which can control and stop cell cycle 

23

Outline the halo method

  1. Solubilise the nuclear membrane with detergent
  2. Extract histones
  3. Nick DNA us UV light and allow chromatid to spread out from attachment points on nuclear matrix to full length

24

How does the addition oncogenes affect the halo?

Giving H-Ras to immortalised cells causes halo to increase in size 

Addition of oncogenes past immortalisation will decrease stability of the halo

25

What is nuclear morphology traditionally used for?

Staining and visualisation down the microscope used by pathologists for cancer diagnosis 

26

What can nuclear morphology tell pathologists?

The grade of a tumour but not the stage 

27

What could be used as a replacement to nuclear morphology?

Biomarkers 

High content imaging

High throughput 

28

What could be used as biomarkers for cancer cells?

Nuclear matrix protein

E.g. NMP22 - however, not tumour specific can only be used if know base level of NMP22 so can see if increases on cancer reoccurence