Short Communication Induction of cancer-specific cytotoxicity towards human prostate and skin cells using quercetin and ultrasound

Bioflavonoids, such as quercetin, have recently emerged as a new class of chemotherapeutic drugs for the treatment of various cancer types, but are marred by their low potency and poor selectivity. We report that a short application of low-frequency ultrasound selectively sensitises prostate and skin cancer cells against quercetin. Pretreatment of cells with ultrasound (20 kHz, 2 W cm , 60 s) selectively induced cytotoxicity in skin and prostate cancer cells, while having minimal effect on corresponding normal cell lines. About 90% of the viable skin cancer cell population was lost within 48 h after ultrasound-quercetin (50mM) treatment. Ultrasound reduced the LC50 of quercetin for skin cancer cells by almost 80-fold, while showing no effect on LC50 for nonmalignant skin cells. British Journal of Cancer advance online publication, 1 February 2005; doi:10.1038/sj.bjc.6602364 www.bjcancer.com & 2005 Cancer Research UK