Azacytidine and Bortezomib in Treating Patients With Relapsed or Refractory Acute Myeloid Leukemia or Myelodysplastic Syndromes

RATIONALE: Drugs used in chemotherapy, such as azacytidine work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Bortezomib may stop the growth of cancer cells by blocking blood flow to the cancer and by blocking some of the enzymes needed for cell growth. Giving azacytidine together with bortezomib may kill more cancer cells. PURPOSE: This phase I trial is studying the side effects and best dose of bortezomib when giving together with azacytidine in treating patients with relapsed or refractory acute myeloid leukemia or myelodysplastic syndromes.