The discovery shows how genes previously not linked to the disease are activated in cancers that have become resistant to hormone treatment.
Scientists identified potential new drug targets and markers that could be used to track cancer progression.
Prostate cancer is fuelled by male hormones via a protein molecule called the androgen receptor.
Standard treatment includes drugs that stop androgen hormones such as testosterone acting on prostate tumours, or cut off their supply.
But in time, the drugs stop working as the cancer overcomes its dependency on external androgens.
Previous studies show how the androgen receptor attaches to and switches on specific genes to drive cancer.
The new research reveals that in tumours that are resistant to hormone therapy, the receptor activates a completely different set of genes, including some associated with the production of sugar and fat.
Scientists at Cambridge University made the discovery after looking at tissue samples from men with prostate cancer.
The findings are published in the journal Cancer Cell.
Study leader Naomi Sharma, from the Cancer Research UK Cambridge Research Institute, said: "This is the first comprehensive tissue study of its kind and shines a new light on the biology of prostate cancer.
"Our understanding so far comes from studies in cells grown in the laboratory. In this sophisticated study using samples directly from patients, we've uncovered a much more complex network of cell messages."