Bortezomib, a boronic acid dipeptide, is a highly selective, reversible inhibitor of the 26S proteasome which primarily functions in the degradation of mis-folded proteins and is essential for the regulation of the cell cycle. Exposure to Bortezomib has been shown to stabilize p21, p27, and p53, as well as the proapoptotic Bid and Bax proteins, caveolin-1, and inhibitor κB-α, which prevents activation of nuclear factor κB-induced cell survival pathways. Bortezomib also promotes the activation of the proapoptotic c-Jun-NH2 terminal kinase, as well as the endoplasmic reticulum stress response. Alteration of the levels of these cellular proteins leads to inhibition of proliferation, migration, and promotion of apoptosis of cancer cells.  Bortezomib is shown to penetrate into cells and inhibit proteasome-mediated intracellular proteolysis of long-lived proteins with a concentration that inhibits 50% of the proteolysis of ∼ μM. The average growth inhibition of 50% value for Bortezomib across the entire panel of 60 cancer cell lines derived from multiple human tumors from the US National Cancer Institute (NCI) is 7 nM. Treatment of PC-3 cells with Bortezomib (100 nM) for 8 h results in the accumulation of cells in G2-M, with a corresponding decrease in the number of cells in G1. Bortezomib kills PC-3 cells at 24 and 48 hr with IC50 of 100 and 20 nM, respectively. Bortezomib induces nuclear condensation at 16–24 hr after treatment. Bortezomib treatment leads to PARP cleavage in a time-dependent manner with concentrations as low as 100 nM being effective at 24 hr. 
Oral curcumin administration has been found to inhibit the development of chemically-induced cancer in animal models of oral (58, 59) , stomach (60, 61) , liver (62) , and colon (63-65) cancer. Apc Min/+ mice have a mutation in the Apc (adenomatous polyposis coli) gene similar to that in humans with familial adenomatous polyposis , a genetic condition characterized by the development of numerous colorectal adenomas ( polyps ) and a high risk for colorectal cancer . Oral curcumin administration has been found to inhibit the development of intestinal adenomas in Apc Min/+ mice (66, 67) . Despite promising results in animal studies, there is presently little evidence that high intakes of curcumin or turmeric are associated with decreased cancer risk in humans. A 30-day phase II clinical trial in 40 smokers with at least eight rectal aberrant crypt foci (ACF; precancerous lesions) found that the number of ACF was significantly lower with a daily supplementation with 4 g/day of curcumin compared to 2 g/day (68) . Several controlled clinical trials in humans designed to evaluate the effect of oral curcumin supplementation on precancerous colorectal lesions, such as adenomas, are under way (69) .