Researchers Find that Male Cancer Cells Silencing X Chromosomes

Only when a female cell has a pair of Xs to pick from does the X chromosome become muted in normal mammal cells. The body's method of balancing the dosage of male and female chromosomes is to randomly turn off an additional X. However, neither the X nor the Y chromosomes need to be inactivated if there is just one X chromosome, as in the majority of male cells.

This generalisation, however, is not always true of cancer cells. Global cancer patients' DNA samples that were made available to the public were used in the study. Researchers discovered the X-inactive specific transcript, or XIST, gene, which silences the X chromosome, is highly expressed in a wider variety of malignant cells than they'd ever anticipated after analysing thousands of genomes from more than 30 different malignancies.

The gene is a non-coding RNA sequence that is present in the placental animals' cells and is essential for the shutting down of X chromosome genes. The reason for this is unknown, however researchers do have some theories. Rapid cancer growth can result in errors like numerous copies of the same chromosome. For instance, the authors occasionally discovered two X chromosomes in cancer cells from men.

It's possible that when this happens, X inactivation is triggered to maintain genetic stability, enhancing the survival and growth of a cancerous tumor.