title: Irinotecan pharmacokinetic and pharmacogenomic alterations induced by methylselenocysteine in human head and neck xenograft tumors.
abstract: The combination of methylselenocysteine and irinotecan (CPT-11) is synergistic against FaDu and A253 xenografts. Methylselenocysteine/CPT-11 increased tumor cure rate to 100% in FaDu and to 60% in A253. In this study, the effect of methylselenocysteine on pharmacokinetic and pharmacogenetic profiles of genes relevant to CPT-11 metabolic pathway was evaluated to identify possible mechanisms associated with the observed combinational synergy. Nude mice bearing tumors (FaDu and A253) were treated with methylselenocysteine, CPT-11, and a combination of methylselenocysteine/CPT-11. Samples were collected and analyzed for plasma and intratumor concentration of CPT-11 and 7-ethyl-10-hydroxyl-camptothecin (SN-38) by high-performance liquid chromatography. The intratumor relative expression of genes related to the CPT-11 metabolic pathway was measured by real-time PCR. After methylselenocysteine treatment, the intratumor area under the concentration-time curve of SN-38 increased to a significantly higher level in A253 than in FaDu and was associated with increased expression of CES1 in both tumors. Methylselenocysteine/CPT-11 treatment, compared with CPT-11 alone, resulted in a significant decrease in levels of ABCC1 and DRG1 in FaDu tumors and an increase in levels of CYP3A5 and TNFSF6 in A253 tumors. No statistically significant changes induced by methylselenocysteine/CPT-11 were observed in the levels of other investigated variables. In conclusion, the significant increase in the cure rate after methylselenocysteine/CPT-11 could be related to increased drug delivery into both tumors (CES1), reduced resistance to SN-38 (ABCC1 and DRG1) in FaDu, and induced Fas ligand apoptosis (TNFSF6) in A253. No correlation was observed between cure rate and other investigated variables (transporters, degradation enzymes, DNA repair, and cell survival/death genes) in either tumor.
authors.affiliation: Department of Cancer Biology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Rami G
authors.initials: RG
authors.lastname: Azrak
authors.forename: Jinsheng
authors.initials: J
authors.lastname: Yu
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Pendyala
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Smith
authors.forename: Shousong
authors.initials: S
authors.lastname: Cao
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: William D
authors.initials: WD
authors.lastname: Shannon
authors.forename: Farukh A
authors.initials: FA
authors.lastname: Durrani
authors.forename: Howard L
authors.initials: HL
authors.lastname: McLeod
authors.forename: Youcef M
authors.initials: YM
authors.lastname: Rustum
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000493:pharmacokinetics* / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D002294:Carcinoma, Squamous Cell / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D003545:Cysteine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D005260:Female; D006258:Head and Neck Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D008819:Mice, Nude; D016566:Organoselenium Compounds / Q000008:administration & dosage; D010597:Pharmacogenetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017279:Selenocysteine / Q000031:analogs & derivatives; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; D016566:Organoselenium Compounds; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D017279:Selenocysteine; D000077146:Irinotecan; D003545:Cysteine; C002979:selenomethylselenocysteine; D002166:Camptothecin