Mice are typically used as models in advanced prostate cancer research, but the profound differences between them and humans has long bedeviled the translation of findings from the animal to success in people. Dogs however are the only other animal that suffers from a significant incidence of prostate cancer, and researchers are finding them much more enlightening subjects in identification of drugs that show promise for human patients.

The findings are described in a paper appearing in the Journal for ImmunoTherapy of Cancer.

Prostate cancer is the most common cancer in men worldwide. At advanced stages, there exist treatments that are effective in most cases for a short while, but eventually the disease progresses past being susceptible to any curative treatment. The prognosis beyond this point is typically gloomy.

Researchers have hypothesized that a particular type of white blood cell — regulatory T cells, or Tregs — may be inhibiting the ability of the immune system to recognize and thereby attack prostate cancer cells (as well as some other types of cancer cells). Tregs play an essential role in the immune system, ensuring that white blood cells that recognize and attack foreign cells don’t mistake the body’s own cells as foreign and attack them. This is why Tregs are sometimes called «suppressor» T cells, as they suppress the immune system and prevent self-attack.

However, it is also thought that some types of cancer cells can trick Tregs into thinking that they also shouldn’t be attacked. Researchers have repeatedly found an excess of Tregs hanging around such cancers — a process they call Treg tumor infiltration, likely misdirecting the other T cells that would otherwise want to attack the tumor as «foreign.»

Activation (more formally, expression) of the gene that controls production of Forkhead box protein 3 (FOXP3) is necessary in turn for the production of Tregs. FOXP3 is a transcription factor, a type of protein that controls the rate of transcription of genes. Transcription is what we call the process of taking genetic information that exists in genes on DNA molecules and packaging that same information in messenger RNA, which then goes on to tell the protein factories in the cell to make a particular type of protein that corresponds to the original gene.

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