Purpose: Our previous study revealed that simultaneously targeting epidermal growth factor receptor (EGFR) tyrosine kinase and cyclooxygenase-2 (COX-2) additively or synergistically inhibited growth of squamous cell carcinoma of the head and neck (SCCHN) in vitro. However, an in vivo efficacy of this combined treatment in SCCHN has not been studied. Experimental Design: Nude mice were pretreated with control (1% Tween 80), ZD1839 (50 mg/kg) alone, celecoxib (50 mg/kg) alone, or a combination of ZD1839 and celecoxib at the same dosages for 7 days before injection of a human SCCHN cell line Tu212.The animals were continuously treated with the agents 5 days a week for about 11weeks. Results: Tumor growth in the combined treatment was significantly inhibited compared with the control (P < 0.001), ZD1839 (P = 0.005), or celecoxib (P < 0.001). At the same time, a dramatic delay of tumor progression was observed in the combined treatment compared with all other three groups. Molecular analysis showed that the combined treatment significantly decreased prostaglandin E metabolite production. The cooperative effect of these two agents in combination was also associated with down-regulation of phosphorylated EGFR, phosphorylated extracellular signal-regulated kinase, and phosphorylated signal transducers and activators of transcription 3 levels and reduction of vascular endothelial growth factor and Ki-67 expression. Specifically, gene silencing of both EGFR and COX-2 by small interfering RNA further confirmed the cooperative antitumor effect. Conclusion:The current results strongly suggest that a cooperative effect of the combined treatment on tumor progression is mediated through blocking both EGFR-and COX-2-related pathways. This combination regimen may provide a promising strategy for cancer therapy and chemoprevention in SCCHN.

Purpose: Constitutive mutational activation of c-kit has been found to be associated with the pathogenesis of gastrointestinal stromal tumors (GISTs). The prognostic significance of c-kit mutations, however, is still controversial.Experimental Design: We examined 86 patients curatively resected for localized GIST. Genomic DNA was extracted from paraffin-embedded tumor tissues. Exons 9, 11, 13, and 17 of the c-kit gene were amplified by PCR and sequenced.Results: Mutations in exon 11 were detected in 61 tumors, and mutations in exon 9 were observed in three tumors, whereas no mutations were detected in exons 13 or 17. The overall c-kit mutation frequency was 74%. Amino acid alterations in the 61 tumors with exon 11 mutations were deletion in 33 tumors, substitution in 20, both deletion and substitution in 4, insertion in 1, and duplication in 3. Histologically, tumors with c-kit mutations showed higher mitotic counts and higher cellularity. The 5-year relapse-free survival (RFS) in patients having GISTs with c-kit mutations was 21%, compared with 60% in those without c-kit mutations. Significantly higher RFS rates were observed in patients with tumors having mitotic counts < 5 mitoses/50 high power field, spindle-cell histology, tumor size < 5 cm, or gastric GISTs. Multivariate analyses indicated association of poorer RFS with a higher mitotic count [>5 of 50 high power fields; odds ratio (OR) ‫؍‬ 3.0], presence of c-kit mutations (OR ‫؍‬ 5.6), and a larger tumor size (>5 cm; OR ‫؍‬ 4.2).Conclusions: The presence of c-kit mutation, along with high mitotic count and larger tumor size, was an independent factor for poor prognosis in patients with localized GISTs.

Head and neck squamous cell carcinoma is a well-known model for chemoprevention studies because of its field cancerization effect, its multistep carcinogenesis process, and the easy accessibility of biopsies to target lesions. With new understandings of head and neck carcinogenesis and the development of molecular targeted therapy, chemoprevention trials for head and neck squamous cell carcinoma have been rapidly updated. Cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors are gaining significant attention as potential chemopreventive agents. Both COX-2 and EGFR are involved in head and neck carcinogenesis. Targeting COX-2 and EGFR separately has shown promising antitumor activity. Recently, combinations of COX-2 and EGFR tyrosine kinase inhibitors have been reported to show synergistic/ additive effects in preclinical studies. Because COX-2 and EGFR tyrosine kinase inhibitors are toxic as single agents in clinical trials, the combination of COX-2 and EGFR tyrosine kinase inhibitors used at lower doses seems more promising than monotherapy with either as a novel strategy in head and neck cancer chemoprevention. [Mol Cancer Ther 2005;4(9):1448 -55]

Clinical prescription of cisplatin, one of the most widely used chemotherapeutic agents, is limited by its side effects, particularly tubular injury-associated nephrotoxicity. Since details of the underlying mechanisms are not fully understood, we investigated the role of pyruvate dehydrogenase kinase (PDK) in cisplatin-induced acute kidney injury. Among the PDK isoforms, PDK4 mRNA and protein levels were markedly increased in the kidneys of mice treated with cisplatin, and c-Jun N-terminal kinase activation was involved in cisplatin-induced renal PDK4 expression. Treatment with the PDK inhibitor sodium dichloroacetate (DCA) or genetic knockout of PDK4 attenuated the signs of cisplatin-induced acute kidney injury, including apoptotic morphology of the kidney tubules along with numbers of TUNEL-positive cells, cleaved caspase-3, and renal tubular injury markers. Cisplatin-induced suppression of the mitochondrial membrane potential, oxygen consumption rate, expression of electron transport chain components, cytochrome c oxidase activity, and disruption of mitochondrial morphology were noticeably improved in the kidneys of DCA-treated or PDK4 knockout mice. Additionally, levels of the oxidative stress marker 4-hydroxynonenal and mitochondrial reactive oxygen species were attenuated, whereas superoxide dismutase 2 and catalase expression and glutathione synthetase and glutathione levels were recovered in DCA-treated or PDK4 knockout mice. Interestingly, lipid accumulation was considerably attenuated in DCA-treated or PDK4 knockout mice via recovered expression of peroxisome proliferator-activated receptor-α and coactivator PGC-1α, which was accompanied by recovery of mitochondrial biogenesis. Thus, PDK4 mediates cisplatin-induced acute kidney injury, suggesting that PDK4 might be a therapeutic target for attenuating cisplatin-induced acute kidney injury.