Exposure of the Dunning R3327AT-3 rat prostatic carcinoma and SK-Mel-28 human melanoma, in vitro, to high energy shock waves resulted in a reduction in cell viability as determined by trypan blue exclusion and a decrease in the number of colonies formed in a clonogenic assay. Flow cytometric determination of DNA content in R3327AT-3 cells treated in vitro indicated a selective diminution of cells in the G2 and M phases of the cell cycle. When R3327AT-3 cells exposed to high energy shock waves were subsequently injected into rats, or tumor bearing animals were treated by high energy shock waves targeted at the tumor, a delay in tumor growth was observed. These observations indicate that high energy shock waves are cytotoxic to tumor cells in vitro and in vivo. Additional research into the possible use of high energy shock waves in the non-invasive destruction of animal and human tumors is warranted.

These data suggest that the mechanism of dietary fat induced growth of human prostate cancer cells is mediated by oxidative stress. It also raises the possibility of a therapeutic benefit of vitamin E in preventing prostate cancer.

Structure-activity relationship (SAR) studies by modification of the unsaturated side chain of potent anticancer marine natural product psymberin/irciniastatin A (1) suggest that substitution at C4 and C5 is important for the cytotoxicity of psymberin, but the terminal double bond is not essential for activity. An aryl group is a good replacement for the olefin. The total synthesis of structurally simplified C11-deoxypsymberin (29) was completed, and its activity is consistently more potent than the natural product which provides a unique opportunity for further SAR studies in the psymberin and pederin family. Preliminary mechanism studies suggest the mode of action of psymberin is through cell apoptosis.

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These data suggest that the mechanism of dietary fat induced growth of human prostate cancer cells is mediated by oxidative stress. It also raises the possibility of a therapeutic benefit of vitamin E in preventing prostate cancer.