RESUMO
During wood decay, the white-rot basidiomycete Phanerochaete chrysosporium secretes low-molecular-mass glycoproteins that catalyze a redox reaction between O(2) and electron donors to produce hydroxyl radical. This reaction accounts for most of the hydroxyl radical produced in wood-degrading cultures of P. chrysosporium. In combination with phenol oxidases, hydroxyl radical is believed to play a role in lignin degradation. The secreted glycoproteins also reduce Fe(III) to Fe(II) and strongly bind Fe(II). The partially purified glycoproteins contain 1-amino-1-deoxy-2-ketose (ketoamine) produced by the condensation of side-chain amino groups and carbohydrate. cDNAs and two putative genes encoding these glycoproteins, glp1 and glp2, have been isolated and sequenced. The 875bp glp1 and 864bp glp2 are found on scaffold 2 of the P. chrysosporium genome. These presumptive genes each consist of seven introns and eight exons. The latter encode a predicted protein of 138 amino acids and a 22-amino-acid signal sequence for secretion. The predicted protein sequences are nearly identical to N-terminal and internal sequences obtained from the partially purified glycoprotein. The molecular masses of the deduced mature proteins, 13,981 (glp1) and 13,970 (glp2), coincide with the molecular mass of the glycoprotein as determined by tricine-SDS-PAGE.
Assuntos
Glicoproteínas/genética , Glicoproteínas/metabolismo , Radical Hidroxila/metabolismo , Phanerochaete/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA Complementar/análise , Proteínas Fúngicas/genética , Proteínas Fúngicas/isolamento & purificação , Proteínas Fúngicas/metabolismo , Glicoproteínas/isolamento & purificação , Modelos Biológicos , Dados de Sequência Molecular , Phanerochaete/metabolismo , Homologia de Sequência de AminoácidosRESUMO
BACKGROUND: The aim of this study was to investigate whether c-myc amplification in human breast cancer is associated with response to neoadjuvant chemotherapy comprising paclitaxel followed by 5-FU/epirubicin/cyclophosphamide (P-FEC). METHODS: Tumour tissue samples were obtained before neoadjuvant chemotherapy (P-FEC) from 100 primary breast cancer patients (stage II/III). C-myc and HER2 amplification were examined by FISH, and oestrogen receptor (ER), progesterone receptor (PR), Ki67, and topoisomerase 2α (TOP2A) expression were examined immunohistochemically. Pathological complete response (pCR) was defined by a complete loss of tumour cells in the breast without any lymph node metastasis. RESULTS: C-myc amplification was observed in 40% (40/100) of breast tumours, and was significantly associated with ER-negative tumours (23/40 for ER(-) versus 17/60 for ER(+), P=0.004), high histological grade tumours (11/18 for grade 3 versus 29/82 for grades 1+2, P=0.043) and TOP2A-positive tumours (28/51 for TOP2A(+) versus 12/49 for TOP2A(-), P=0.002). pCR rate was 20% for total patients (10.0% for ER(+) and 35.0% for ER(-)). Further, breast tumours with c-myc amplification (c-myc(+)) showed a significantly (P=0.041) higher pCR rate (12/40) than those without such amplification (c-myc(-)) (8/60). This association between pCR and c-myc amplification was observed in ER-positive tumours (4/17 for c-myc(+) versus 2/43 for c-myc(-), P=0.048) but not in ER-negative tumours (8/23 for c-myc(+) versus 6/17 for c-myc(-), P=0.973). CONCLUSION: Our results suggest that c-myc amplification is significantly associated with a high pCR rate to P-FEC in breast tumours, especially in ER-positive tumours.