title: UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 6 (ppGalNAc-T6) mRNA as a potential new marker for detection of bone marrow-disseminated breast cancer cells.
abstract: The evaluation of disseminated epithelial tumor cells in patients with early stages of breast cancer has generated considerable interest because of its potential association with poor clinical outcome. Considering that O-glycosylation pathways are frequently altered in breast cancer, we performed this work to evaluate the potential usefulness of UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) (a family of glycosyltransferases which catalyze the first key step of mucin-type O-glycosylation) to detect disseminated cells in bone marrow samples from patients with operable breast cancer. Using RT-PCR assays, we studied the gene expression of 9 enzymes (ppGalNAc-T1-T9). Among the ppGalNAc-Ts expressed by breast tumors (-T1, -T2, -T3, -T6 and -T7), the best specificity (negative results on all PBMN cell samples from healthy donors) was shown for ppGalNAc-T6. Thus, we selected this enzyme as a target gene for further evaluation. ppGalNAc-T6 mRNA was found in 22/25 (88%) breast cancer samples, in all 3 human breast cancer cell lines evaluated (MCF-7, ZR75-1 and T47D), in 1/30 (3%) PBMN cells and 0/19 bone marrow samples obtained from patients without cancer. Using this method, 22/61 (36%) patients with breast cancer, who underwent curative surgery, showed positive ppGalNAc-T6 mRNA in bone marrow aspirates obtained prior to surgery, including 11/34 patients with stage-I or -II, without histopathological lymph node involvement. In a preliminary follow-up evaluation, 19/61 patients experienced recurrence of the disease. ppGalNAc-T6 was positive in 11/19 (57.9%) of these patients. Interestingly, in the group of patients without lymph node involvement, disease recurrence was observed in 54.5% of patients who showed ppGalNAc-T6 mRNA-positive bone marrow aspirates and only in 4.3% of patients when ppGalNAc-T6 was negative (p = 0.014). These results indicate that ppGalNAc-T6 mRNA could be a specific marker applicable to the molecular diagnosis of breast cancer cells dissemination.
authors.affiliation: Laboratorio de Oncología Básica y Biología Molecular, Dpto. de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Teresa
authors.initials: T
authors.lastname: Freire
authors.forename: Nora
authors.initials: N
authors.lastname: Berois
authors.forename: Cecilia
authors.initials: C
authors.lastname: Sóñora
authors.forename: Mario
authors.initials: M
authors.lastname: Varangot
authors.forename: Enrique
authors.initials: E
authors.lastname: Barrios
authors.forename: Eduardo
authors.initials: E
authors.lastname: Osinaga
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D001854:Bone Marrow Cells / Q000201:enzymology* / Q000473:pathology; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics* / Q000378:metabolism; D009362:Neoplasm Metastasis / Q000175:diagnosis; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D017350:N-Acetylgalactosaminyltransferases; C121529:UDP-N-acetylgalactosamine polypeptide N-acetylgalactosaminyltransferase 6