Chromosomes are now well known to be located in their specific positions within the nucleus. Different CHROMOSOMAL TERRITORIES hold some specific chromosomes. So if some genes are within a specific territory, will its expression then depend entirely on its position.
Also do cancerous cell and normal cells have same CHROMOSOMAL TERRITORY pattern? As changing the address of a gene from one territory to another may drastically change its expression! Importantly are there any reports about Territory shifting/alteration between cancerous and normal cells?
No, they do not always have same chromosomal territory pattern. They may sometimes have same pattern though.
There are multiple factors that may affect the chromosomal territory pattern. One of the main factor in my view is carcinogen that induced transformation.
Also, even if genes are in same location, they may or may not have same expression pattern. In case of most of cell cycle and metabolic genes have altered expression pattern in cancer cell, even if gene location is same.
Cancer cells are highly aneuploids. For example if you check the paper 2013 Nature genetic: Pan-cancer patterns of somatic copy number alteration, you can see from huge bioinfo analysis that cancer tumors present in general around 11-64% of it genome at >3n. So if you have more chromosomes inside your nuclei, you clearly affect the chromosome territory and interaction between them.
Hi Mohammad,
Most cancer cells are aneuploids (with genome >3n) with genomic instability. hence, the chromosomal territory is no longer respected and there's a chaos going on in the nucleus.
Let alone the fact, that many cancers (notably, hematological ones) are a result of a chromosomal translocation, some balanced and some unbalanced, and that highly affects the position of the corresponding genes, and thus their expression. For example, CML is due to t(9,22) while APL to t(15,22) Such chromosomal translocation is termed interchromosomal because it involves the translocation of loci on different chromosomes, you might also find, intrachromosomal translocation in which, loci on the same chromosome is exchanged. In normal cells, under steady state, you wouldn't have such aberrant chromosomal translocation unless there's an external action driving mutations inside the cells.
Hope this helps,
Patrick
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