Provided are methods of inhibiting CYP17 in a mammal, such as a human, that include administering an effective amount of at least one CYP17 inhibitor, such as VN/124-1, VN/125-1, VN/85-1, VN/87-1 and/or VN/108-1 to the mammal. Also provided are methods of down regulating androgen receptor (AR) protein expression and methods of antagonizing AR in a mammal that include administering to the mammal an effective amount of at least one active ingredient selected from VN/124-1, VN/125-1, VN/85-1, VN/87-1 and VN/108-1. Also provided are methods of treating prostate cancer and methods of suppressing or preventing prostate tumor growth by administering such compounds to a mammal.
