Introduction Molecular and cellular characteristics of the relapse-prone subset within triple-negative breast cancer (TNBC) remain unclear. Aberrant glycosylation is involved in the malignant behavior of cancer cells. In the present study, we aimed to reveal glycan profiles unique to relapsed TNBC patients. Methods Thirty TNBC patients who did not undergo neoadjuvant chemotherapy but postoperative standard adjuvant therapy from 2009 through 2016 at Juntendo Hospital were investigated. TNBC cells were resected from primary breast cancer sections of formalin-fixed surgical specimens using laser-assisted microdissection. The binding intensities of the extracted glycoproteins to 45 lectins were quantified using lectin microarray and compared between relapsed and non-relapsed patients. Immunohistochemical staining with TJA-II lectin in specimen sections was performed. Results Five patients relapsed during the follow-up (range 37–123 months). Lectin microarray analysis revealed that 7 out of 45 lectins showed significant differences in binding intensity between the relapsed and the non-relapsed group. TJA-II, ACA, WFA, and BPL showed stronger binding in the relapsed group. PNGase F treatment of TNBC cell lysates suggested that TJA-II and ACA bind O-glycans. TJA-II staining of tissue sections revealed strong binding to cell surface membranes and to the cytoplasm of TNBC cells, but not to other types of cells. Significantly more TNBC cells were stained in tissue sections from relapsed than non-relapsed patients. Conclusions TNBC cells from relapsed patients showed a unique lectin reactivity, with higher levels of TJA-II (also WFA and BPL) binding than in non-relapsed patients. The results are potentially useful to develop new prognostic and therapeutic tools.

Adjuvant chemotherapy has played a major role in the treatment of hormone receptor-positive breast cancer for many years. To better determine which patient subsets need adjuvant chemotherapy, various gene expression analyses have been developed, but cost-effective tools to identify such patients remain elusive. In the present report, we retrospectively investigated immunohistochemical expression and subcellular localization of MUC1 in primary tumors and examined their relationship to tumor malignancy, chemotherapy effect and patient outcomes. We retrospectively examined three patient cohorts with hormone receptor-positive/human epidermal growth factor receptor 2-negative invasive breast cancer: 51 patients who underwent 21-gene expression analysis (multi-gene assay-cohort), 96 patients who received neoadjuvant chemotherapy (neoadjuvant chemotherapy-cohort), and 609 patients whose tumor tissue was used in tissue-microarrays (tissue-microarray-cohort). The immunohistochemical staining pattern of the anti-MUC1 monoclonal antibody, Ma695, was examined in cancer tissues, and subcellular localization was determined as apical, cytoplasmic or negative. In the multi-gene assay-cohort, tumors with apical patterns had the lowest recurrence scores, reflecting lower tumor malignancy, and were significantly lower than MUC1-negative tumors (P = 0.038). In the neoadjuvant chemotherapy-cohort, there was no correlation between MUC1 staining patterns and effects of chemotherapy. Finally, in the tissue-microarray-cohort, we found that patients with apical MUC1 staining patterns had significantly longer disease-free-survival and overall survival than other patterns (P = 0.020 and 0.039, respectively). Our data suggest that an apical MUC1 staining pattern indicates luminal A-likeness. Assessment of the subcellular localization of MUC1 glycoprotein may be useful for identifying patients who can avoid adjuvant chemotherapy.

Background/Aim: Triple-negative breast cancer (TNBC) remains difficult to treat and new molecular targets are needed. Here, we investigated the impact of glycosyltransferase genes on TNBC patient survival. Patients and Methods: mRNA expression levels of 101 glycosyltransferase genes in TNBC patients were compared for correlation with patient survival using The Cancer Genome Atlas data. An antibody to β-3-Nacetylgluco-saminyltransferase 8 (B3GNT8) was applied to investigate B3GNT8 protein distribution and expression levels in 23 TNBC surgical specimens. Results: B3GNT8 mRNA levels inversely correlated with relapse-free survival (p<0.01) and overall survival (p<0.05) in TNBC patients. Anti-B3GNT8 antibody binding was observed as dots in the cytoplasm of cancer cells. These dots were supposed to correspond to B3GNT8 protein in tumour cells, but their number was smaller in relapsed patients than in non-relapsed patients. Conclusion: B3GNT8 mRNA expression levels in TNBC tumour tissues are potentially useful in distinguishing patients with favourable and poor clinical outcomes.Triple-negative breast cancer (TNBC) comprises approximately 15% of breast cancers and is defined by the lack of oestrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor-2 (HER2) overexpression (1, 2). Because of the lack of therapeutic molecular targets, TNBC patients receive standard chemotherapy treatments, commonly anthracycline followed by taxane. However, in the adjuvant setting only about one third of TNBC patients respond to such therapy. In patients who still have residual cancer after these treatments, the prognosis is poor (3). We focused on cellular glycosylation, because it has been shown by many experimental and clinical investigations that it is involved in malignant progression and metastasis in cancer (4, 5). In breast cancer, glycosylation has been implicated in cancer cell growth and metastasis (6). Song and co-workers showed that GALNT14, a glycosyltransferase, which transfers Nacetylgalactosamine (GalNAc) to polypeptides, promotes lung-specific breast cancer metastasis (7). As an upstream event, a transcriptional activator protein, LAMTOR5, was reported to modulate GALNT1 activity in breast cancer leading to abnormal O-glycosylation (8). However, the biological and clinical significance of glycosylation in TNBC has not been previously investigated.Since glycosylation is controlled by glycosyltransferases, we conducted a comprehensive search on 101 glycosyltransferase genes in TNBC patients who did not receive neoadjuvant chemotherapy for correlation with their survival using The Cancer Genome Atlas (TCGA) mRNA expression database. From this search, β-3-N-acetylglucosaminyltransferase 8 (B3GNT8) emerged as a gene whose expression inversely correlated with the survival of TNBC patients. B3GNT8 is a 845 This article is freely accessible online.