Researchers have discovered that bladder cells in men are more susceptible to the selective growth of dangerous mutations even before the development of bladder cancer, and smoking is also considered an important factor in the development of cancer.
The study was conducted by researchers from the University of Washington in the United States, and the Institutional Research Council in Barcelona, Spain, and its results were published in the journal Nature on October 8, and the Eurick Alert website wrote about it.
Bladder cancer is one of the most common types of cancer worldwide. Men are approximately four times more susceptible to it than women, and smoking is the main known environmental risk factor.
Cancer does not arise overnight. Over decades, mutations accumulate in tissue cells, and some clones gain an advantage that allows them to grow faster than others. This study shows that these differences are already evident in healthy tissue before the disease appears.
The researchers analyzed bladder samples from 45 donors. They were able to discover and quantify thousands of mutations.
Smoking stimulates mutations
“Healthy tissues accumulate many mutations throughout life, but what matters is not only how many there are, but also which ones succeed in overtaking others and expand into clones, which are copies of the same cell carrying the same mutations,” explains Dr. López Bigas, a researcher at the Catalan Foundation for Advanced Research and Studies, and leader of the Biomedical Genomics Group at the Barcelona Institutional Research Council.
“We noticed that smoking and biological sex directly affect this process,” he adds.
Researchers noted clear biological differences between men and women. Some of the male donors’ mutations in cancer-related genes showed a feature such that the cells carrying them were more likely to expand even in healthy bladders.
They also noticed a noticeable effect of smoking. Among donors over the age of 55, those with a history of smoking had a high proportion of mutations in the TERT promoter, a DNA element that reactivates telomerase and allows cells to avoid senescence and continue dividing.
This work provides evidence that tobacco is not only a cause of new mutations but is also a transcriptional inducer, facilitating the expansion of cells with pre-existing mutations.