Potent Antitumor Activity of a Novel Cationic Pyridinium-Ceramide Alone or in Combination with Gemcitabine against Human Head and Neck Squamous Cell Carcinomas in Vitro and in Vivo

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 317; no. 3; pp. 1188 - 1199
• Main Authors: Senkal, Can E, Ponnusamy, Suriyan, Rossi, Michael J, Sundararaj, Kamala, Szulc, Zdzislaw, Bielawski, Jacek, Bielawska, Alicja, Meyer, Mario, Cobanoglu, Bengu, Koybasi, Serap, Sinha, Debajyoti, Day, Terry A, Obeid, Lina M, Hannun, Yusuf A, Ogretmen, Besim
• Format: Journal Article
• Language: English
• Published: United States American Society for Pharmacology and Experimental Therapeutics 01.06.2006
• Subjects: Animals; Antineoplastic Combined Chemotherapy Protocols - adverse effects; Antineoplastic Combined Chemotherapy Protocols - pharmacokinetics; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Cations; Cell Line, Tumor; Cell Proliferation - drug effects; Ceramides - administration & dosage; Ceramides - adverse effects; Ceramides - pharmacokinetics; Ceramides - therapeutic use; Deoxycytidine - administration & dosage; Deoxycytidine - adverse effects; Deoxycytidine - analogs & derivatives; Deoxycytidine - pharmacokinetics; Deoxycytidine - therapeutic use; Dose-Response Relationship, Drug; Head and Neck Neoplasms - drug therapy; Head and Neck Neoplasms - pathology; Humans; Inactivation, Metabolic; Maximum Tolerated Dose; Mice; Mice, Inbred BALB C; Mice, SCID; Neoplasms, Squamous Cell - drug therapy; Neoplasms, Squamous Cell - pathology; Pyridinium Compounds - administration & dosage; Pyridinium Compounds - adverse effects; Pyridinium Compounds - pharmacokinetics; Pyridinium Compounds - therapeutic use; Tissue Distribution; Xenograft Model Antitumor Assays
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.106.101949

In this study, a cationic water-soluble ceramide analog l - threo -C 6 -pyridinium-ceramide-bromide ( l -t-C 6 -Pyr-Cer), which exhibits high solubility and bioavailability, inhibited the growth of various human head and neck squamous cell carcinoma (HNSCC) cell lines at low IC 50 concentrations, independent of their p53 status. Consistent with its design to target negatively charged intracellular compartments, l -t-C 6 -Pyr-Cer accumulated mainly in mitochondria-, and nuclei-enriched fractions upon treatment of human UM-SCC-22A cells [human squamous cell carcinoma (SCC) of the hypopharynx] at 1 to 6 h. In addition to its growth-inhibitory function as a single agent, the supra-additive interaction of l -t-C 6 -Pyr-Cer with gemcitabine (GMZ), a chemotherapeutic agent used in HNSCC, was determined using isobologram studies. Then, the effects of this ceramide, alone or in combination with GMZ, on the growth of UM-SCC-22A xenografts in SCID mice was assessed following the determination of preclinical parameters, such as maximum tolerated dose, clearance from the blood, and bioaccumulation. Results demonstrated that treatment with l -t-C 6 -Pyr-Cer in combination with GMZ significantly prevented the growth of HNSCC tumors in vivo. The therapeutic efficacy of l -t-C 6 -Pyr-Cer/GMZ combination against HNSCC tumors was approximately 2.5-fold better than that of the combination of 5-fluorouracil/cis-platin. In addition, liquid chromatography/mass spectroscopy analysis showed that the levels of l -t-C 6 -Pyr-Cer in HNSCC tumors weresignificantly higher than its levels in the liver and intestines; interestingly, the combination with GMZ increased the sustained accumulation of this ceramide by approximately 40%. Moreover, treatment with l -t-C 6 -Pyr-Cer/GMZ combination resulted in a significant inhibition of telomerase activity and decrease in telomere length in vivo, which are among downstream targets of ceramide.