title: SET overexpression decreases cell detoxification efficiency: ALDH2 and GSTP1 are downregulated, DDR is impaired and DNA damage accumulates.
abstract: Alcohol and tobacco consumption are risk factors for head and neck squamous cell carcinoma (HNSCC). Aldehyde dehydrogenase 2 (ALDH2) and glutathione S-transferase pi 1 (GSTP1) are important enzymes for cellular detoxification and low efficiencies are implicated in cancer. We assessed the potential role of SET protein overexpression, a histone acetylation modulator accumulated in HNSCC, in gene regulation and protein activity of ALDH2 and GSTP1. SET was knocked down in HN13, HN12 and Cal27, and overexpressed in HEK293 cells; ethanol and cisplatin were the chemical agents. Cells with SET overexpression (HEK293/SET, HN13 and HN12) showed lower ALDH2 and GSTP1 mRNA levels and trichostatin A increased them (real-time PCR). Ethanol upregulated GSTP1 and ALDH2 mRNAs, whereas cisplatin upregulated GSTP1 in HEK293 cells. SET-chromatin binding revealed SET interaction with ALDH2 and GSTP1 promoters, specifically via SET NAP domain; ethanol and cisplatin abolished SET binding. ALDH2 and GSTP1 efficiency was assessed by enzymatic and comet assay. A lower ALDH2 activity was associated with greater DNA damage (tail intensity) in HEK293/SET compared with HEK293 cells, whereas HN13/siSET showed ALDH2 activity higher than HN13 cells. HN13/siSET cells showed increased tail intensity. Cisplatin-induced DNA damage response showed negative relationship between SET overexpression and BRCA2 recruitment. SET downregulated repair genes ATM, BRCA1 and CHEK2 and upregulated TP53. Cisplatin-induced cell-cycle arrest occurred in G(0) /G(1)  and S in HEK293 cells, whereas HEK293/SET showed G(2) /M stalling. Overall, cisplatin was more cytotoxic for HN13 than HN13/siSET cells. Our data suggest a role for SET in cellular detoxification, DNA damage response and genome integrity.
authors.affiliation: Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903 Ribeirão Preto, SP, Brazil.
authors.forename: Luciana O
authors.initials: LO
authors.lastname: Almeida
authors.forename: Renata N
authors.initials: RN
authors.lastname: Goto
authors.forename: Cezar R
authors.initials: CR
authors.lastname: Pestana
authors.forename: Sérgio A
authors.initials: SA
authors.lastname: Uyemura
authors.forename: Silvio
authors.initials: S
authors.lastname: Gutkind
authors.forename: Carlos
authors.initials: C
authors.lastname: Curti
authors.forename: Andréia M
authors.initials: AM
authors.lastname: Leopoldino
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics*; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D002460:Cell Line; D004249:DNA Damage; D004268:DNA-Binding Proteins; D015536:Down-Regulation; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D056488:Histone Chaperones / Q000235:genetics*; D006801:Humans; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D056488:Histone Chaperones; C513473:SET protein, human; D014157:Transcription Factors; C096127:ALDH2 protein, human; D000444:Aldehyde Dehydrogenase; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D051549:Glutathione S-Transferase pi