Define the following terms:
- cancer stem cells
- cancer cell lineages
- tumour heterogeneity
Curriculum Reference: Introduction To Neoplasms
Again, no change from the 2009 version of this question.
Cancer Stem Cells
Cancer stem cells, or tumour clonagens, are a concept of either:
- The initial cell which gives initially gives rise to a neoplasm
- The population of cells within a tumour which drives the production of new cancer cells, each of which is able to completely regenerate the primary tumour in the event of sterility of all other stem cells.
Cancer Cell Lineage
In classic tumourigenesis, all cancer cells arise from a single progenitor (the first cancer stem cell). Therefore, a single stem cell gives rise to progeny that, if charted, form a cancer cell lineage.
The descendants of a single cancer stem cell are said to monoclonal, descended from the same ‘clone’. For instance, a myeloma will often produce a specific immunoglobulin, giving a 'monoclonal band' on protein electrophoresis.
Tumour heterogeneity refers to that despite the proposed origin from a single cancer stem cell, neoplasms contain a variety of different cell types. These may include cancer stem cells, terminally differentiated cancer cells, and supporting cells such as endothelium and fibrocytes. Tumour cells themselves may have different genomes and epigenetic changes, brought about by different environmental stimuli (eg. hypoxia in the tumour core) and genomic instability.