Bortezomib With or Without Hormone Therapy in Treating Patients With Relapsed Prostate Cancer

RATIONALE: Bortezomib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Androgens can cause the growth of prostate cancer cells. Drugs, such as goserelin, leuprolide, flutamide, or bicalutamide, may stop the adrenal glands from making androgens. Giving bortezomib with hormone therapy may kill more tumor cells. PURPOSE: This phase II trial is studying how well giving bortezomib with or without hormone therapy works in treating patients with relapsed prostate cancer.