Haematological malignancies Flashcards
What are the ways in which tumour suppressor genes and oncogenes can be aberrantly affected in cancer? (6)
- Gain/loss of whole/parts of chromosomes (aneuploidy)
- Gene deletion/duplication/amplification
- Genomic rearrangements
- Epigenetic changes
- Pathogenic variants
- Small insertions/deletions
What is an example of aneuploidy in cancer?
- Trisomy 8 in myeloid leukaemia
- Results in upregulation of c-MYC proto-oncogene
Which gene is amplified in neuroblastoma?
n-MYC
What is an example of loss of large chromosomal regions in cancer?
- Isodicentric chromosome 17 resulting in the loss of 17p and the deletion of TP53
- del5q
-del7q
What are examples of genomic rearrangement in cancer? (3)
- Translocation, inversion and insertion resulting in generation of fusion-oncogenes or the silencing of tumour suppressor genes
- TMPRSS2-ERG in prostate cancer
- IGH-BCL2 in follicular lymphoma
What are the features of fusion genes? (2)
- They can be specific to a disease and therefore useful diagnostic markers and therapeutic targets
- Some fusion genes are sufficient to cause disease so abnormalities don’t need to be accumulated to cause the cancer as it can be done in ‘1 hit’ (mostly childhood cancers)
What is chromothripsis? (3)
- Complex chromosomal rearrangement where major levels of DNA damage result in genome fragmentation
- Usually causes apoptosis but cancer cells can evade this and end up with a highly complex and abnormal genome
- Results in more genetic diversity and increased likelihood of competitive clones being produced
How are epigenetic changes involved in cancer? (2)
- Methylation of upstream regulatory elements of genes often results in transcriptional suppression
- Methylation status of tumour suppressor genes and oncogenes can be modified to alter expression
How are pathogenic variants involved in cancer? (2)
- Point mutations can inactivate tumour suppressor gene function
- E.g. isodicentric 17 results in loss of one copy of TP53, an inactivating point mutation/frameshift mutation in the other copy would worsen patient prognosis
What is the prognosis for trisomy 8? (3)
- Intermediate/poor
- cMYC amplification which is a transcription factor for cell cycle progression and inhibition of anti-proliferation genes
- Seen in myeloid disease rather than lymphoid
How often is c-MYC constitutively active in cancer?
Approx 70%
What is the prognosis for del5q? (2)
- Good is seen as the sole abnormality in MDS as linked to low risk progression to AML
- Poor if consistent with progression as common marker of therapy-related leukaemia
What is the prognosis for trisomy 7? (3)
- Poor/very poor
- Highly complex set of candidate genes present on chromosome 7
- Associated with likely progression to acute leukaemia
What is an example of epigenetic changes in cancer?
Barrett’s oesophagus
What are examples of point mutations seen in AML? (2)
- NPM1
- FLT3
What are the 3 major strategies for cancer treatment?
- Surgery (removal)
- Radiotherapy (DNA damage)
- Chemotherapy (DNA damage)
What are the haematological malignancies? (2)
- Cancers of the blood or blood forming tissues (bone marrow, lymphatic system, peripheral blood)
- Account for approximately 3% of all cancers
What is the most common haematological malignancy seen in children?
Acute lymphoblastic leukaemia (ALL)
Which haematological malignancies are more common in the elderly? (2)
- Acute myeloid leukaemia (AML)
- Myelodysplastic syndrome (MDS)
How rare are haematological malignancies?
Approximately 63 new cases per 100 000 individuals per year
What are the 3 major disease classes of haematological malignancy?
- Leukaemia
- Lymphoma
- Multiple Myeloma
(- Myelodysplastic syndromes (MDS) are precancerous disorders that can progress to AML)