Abstract P1-07-21: N-glycosylation changes in tumour cells are associated with vascular invasion and metastasis in breast cancer patients
Authors: Milde-Langosch Karin , Karius Tosca , Schütze Dina , Wikman Harriet , Witzel Isabell , Oliveira-Ferrer Leticia , Müller Volkmar , Schumacher Udo 
Published: May 2015

Background: In a recent study based on cDNA microarray data of breast cancer patients, we could show that the mRNA expression of some glycosylation enzymes involved in synthesis and trimming of N-glycansis significantly associated with metastasis and recurrence in breast cancer patients suggesting an important role of N-glycosylation in tumour progression (Milde-Langosch et al., Breast Cancer Res Treat 2014). The aim of the present study was to further investigate this issue on a protein and glycoprotein level (1.) by western blot analysis of selected glycosylation enzymes and (2.) by lectin histochemistry using lectins which bind to O- and/or N-glycans.

Methods: In order to confirm the role of two selected glycosylation enzymes, ribophorin (RPN1) and mannosidase (MAN1A1) on protein level, we analyzed their expression in a cohort of 196 breast cancer samples by western blot analysis. In addition, we studied tumour cell binding of various lectins, which recognize diverse O- or N-glycans (UEA1, HPA, PNA, GNA, PHA-L), using a tissue microarray with up to 293 evaluable breast cancer samples. These results were correlated with recurrence-free survival (RFS) and overall survival (OS) and data on vascular and lymphatic invasion.

Results: By western blot analysis, the negative prognostic significance of ribophorin (RPN1), a key enzyme of N-glycosylation, was corroborated on a protein level. For MAN1A1 which is involved in trimming of N-glycan structures, two isoforms with different molecular weight could be detected on western blots, showing contradictory associations with OS. Protein levels of RPN1 and total MAN1A1 showed significant correlations to the respective mRNA expression data. By lectin histochemistry, we found significant correlations of lectin binding to lymph node metastasis, vascular invasion and lymphangiosis in breast cancer samples. Binding of PHA-L and GNA (binding to N-glycans) and PNA (binding to O- and N-glycans) was significantly associated with vascular invasion, whereas PNA and PHA-L binding correlated with lymph node involvement. In addition, PNA and HPA reactivity was associated with microscopically detected lymphangiosis. PNA binding also correlated with shorter RFS and OS.

Conclusion: While the role of O-glycans in breast cancer metastasis has already been described, our data point to an additional strong impact of N-glycosylation on metastasis and progression of mammary carcinomas.

Citation Format: Karin Milde-Langosch, Tosca Karius, Dina Schütze, Harriet Wikman, Isabell Witzel, Leticia Oliveira-Ferrer, Volkmar Müller, Udo Schumacher. N-glycosylation changes in tumour cells are associated with vascular invasion and metastasis in breast cancer patients [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-07-21.