PURPOSE: Proteasome inhibition has been shown to be effective in multiple myeloma and solid tumor models. In this in vitro study, we investigated the antitumor effect of bortezomib (Velcade((R))) in squamous cell carcinoma of the head and neck (SCCHN) cell lines and examined the interaction of the drug with docetaxel (TAX) and cisplatin (CDDP). METHODS: Dose escalation studies were performed with eight squamous cell carcinoma cell lines using bortezomib alone or in combination with TAX or CDDP. Growth inhibitory and proapoptotic effects were measured quantitatively using cytohistology and western blot analysis. RESULTS: Bortezomib alone showed a significant antiproliferative activity in all SCCHN cell lines (P = 0.012), and the activity was further enhanced by the addition of TAX or CDDP (P
