title: 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.
abstract: In this study, a cationic water-soluble ceramide analog L-threo-C6-pyridinium-ceramide-bromide (L-t-C6-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 IC50 concentrations, independent of their p53 status. Consistent with its design to target negatively charged intracellular compartments, L-t-C6-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-C6-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-C6-Pyr-Cer in combination with GMZ significantly prevented the growth of HNSCC tumors in vivo. The therapeutic efficacy of L-t-C6-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-C6-Pyr-Cer in HNSCC tumors were significantly 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-C6-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.
authors.affiliation: Medical University of South Carolina, Department of Biochemistry, 173 Ashley Avenue, Charleston, SC 29424, USA.
authors.forename: Can E
authors.initials: CE
authors.lastname: Senkal
authors.forename: Suriyan
authors.initials: S
authors.lastname: Ponnusamy
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rossi
authors.forename: Kamala
authors.initials: K
authors.lastname: Sundararaj
authors.forename: Zdzislaw
authors.initials: Z
authors.lastname: Szulc
authors.forename: Jacek
authors.initials: J
authors.lastname: Bielawski
authors.forename: Alicja
authors.initials: A
authors.lastname: Bielawska
authors.forename: Mario
authors.initials: M
authors.lastname: Meyer
authors.forename: Bengu
authors.initials: B
authors.lastname: Cobanoglu
authors.forename: Serap
authors.initials: S
authors.lastname: Koybasi
authors.forename: Debajyoti
authors.initials: D
authors.lastname: Sinha
authors.forename: Terry A
authors.initials: TA
authors.lastname: Day
authors.forename: Lina M
authors.initials: LM
authors.lastname: Obeid
authors.forename: Yusuf A
authors.initials: YA
authors.lastname: Hannun
authors.forename: Besim
authors.initials: B
authors.lastname: Ogretmen
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002412:Cations; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002518:Ceramides / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D003841:Deoxycytidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008658:Inactivation, Metabolic; D020714:Maximum Tolerated Dose; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D018307:Neoplasms, Squamous Cell / Q000188:drug therapy* / Q000473:pathology; D011726:Pyridinium Compounds / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D014018:Tissue Distribution; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
chemical_list: D002412:Cations; D002518:Ceramides; D011726:Pyridinium Compounds; D003841:Deoxycytidine; D000093542:Gemcitabine