Leopoldino, Andreia M.
Squarize, Cristiane H.
Garcia, Cristiana B.
Almeida, Luciana O.
Pestana, Cezar R.
Sobral, Lays M.
Uyemura, Sergio A.
Tajara, Eloiza H.
Gutkind, J. Silvio
Total Authors: 10
 Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Anal Clin Toxicol & Bromatol, BR-14040930 Ribeirao Preto, SP - Brazil
 Univ Michigan, Sch Dent, Dept Periodont & Oral Med, Div Oral Pathol Med Radiol, Ann Arbor, MI 48109 - USA
 Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Fis & Quim, BR-14040930 Ribeirao Preto, SP - Brazil
 Fac Med Sao Jose do Rio Preto, Dept Biol Mol, Sao Jose do Rio Preto - Brazil
 Univ Sao Paulo, Inst Ciencias Biol, Dept Biol, BR-14040930 Ribeirao Preto, SP - Brazil
Web of Science Citations:
Objectives: Determination of the SET protein levels in head and neck squamous cell carcinoma (HNSCC) tissue samples and the SET role in cell survival and response to oxidative stress in HNSCC cell lineages. Materials and Methods: SET protein was analyzed in 372 HNSCC tissue samples by immunohistochemistry using tissue microarray and HNSCC cell lineages. Oxidative stress was induced with the pro-oxidant tert-butylhydroperoxide (50 and 250 mu M) in the HNSCC HN13 cell lineage either with (siSET) or without (siNC) SET knockdown. Cell viability was evaluated by trypan blue exclusion and annexin V/propidium iodide assays. It was assessed caspase-3 and -9, PARP-1, DNA fragmentation, NM23-H1, SET, Akt and phosphorylated Akt (p-Akt) status. Acidic vesicular organelles (AVOs) were assessed by the acridine orange assay. Glutathione levels and transcripts of antioxidant genes were assayed by fluorometry and real time PCR, respectively. Results: SET levels were up-regulated in 97% tumor tissue samples and in HNSCC cell lineages. SiSET in HN13 cells (i) promoted cell death but did not induced caspases, PARP-1 cleavage or DNA fragmentation, and (ii) decreased resistance to death induced by oxidative stress, indicating SET involvement through caspase-independent mechanism. The red fluorescence induced by siSET in HN13 cells in the acridine orange assay suggests SET-dependent prevention of AVOs acidification. NM23-H1 protein was restricted to the cytoplasm of siSET/siNC HN13 cells under oxidative stress, in association with decrease of cleaved SET levels. In the presence of oxidative stress, siNC HN13 cells showed lower GSH antioxidant defense (GSH/GSSG ratio) but higher expression of the antioxidant genes PRDX6, SOD2 and TXN compared to siSET HN13 cells. Still under oxidative stress, p-Akt levels were increased in siNC HN13 cells but not in siSET HN13, indicating its involvement in HN13 cell survival. Similar results for the main SET effects were observed in HN12 and CAL 27 cell lineages, except that HN13 cells were more resistant to death. Conclusion: SET is potential (i) marker for HNSCC associated with cancer cell resistance and (ii) new target in cancer therapy. (C) 2012 Elsevier Ltd. All rights reserved. (AU)