Practical: Cytogenetic Abnormalities in Tumour Cells

Question 1

Examples of large-scale changes in the cancer genome:

Answer 1

• Aneuploidy; gain or loss of entire copies of chromosomes (atypical number as a result)
• Translocation; parts of one chromosome exchanged for another

-> Dysregulation of gene function -> abnormal cell growth

Question 2

Clinical application of cytogenetic analysis:

Answer 2

• Karyotyping has both diagnostic and prognostic significance

Question 3

When are chromosomes best visualised?

Answer 3

• Metaphase
• Most condensed stage -> most visible

Question 4

Example of metaphase arresting drug:

Answer 4

Colcemid…

• Disrupts spindle fibers
• Prevents progression to anaphase

Question 5

Cytogenetic analysis practical: Method overview

Answer 5

• Arrest cells in metaphase using Colcemid
• Treat with hypotonic solution
• Preserve swollen state using a fixative
• Stain with giemsa on slides
• Use microscope to count chromosomes -> euploid or aneuploid?

Question 6

Key cancer cell lines:

Answer 6

• HeLa-S3 (Cervical carcinoma)
• MDA-MB-231 (metastatic breast cancer)
• Jurkat (acute lymphocyte leukaemia)