sLex expression in invasive micropapillary breast carcinoma is associated with poor prognosis and can be combined with MUC1/EMA as a supplementary diagnostic indicator

Objective: Mucin 1 (MUC1/EMA) and sialyl Lewis X (sLe(x)) indicate polarity reversal in invasive micropapillary carcinoma (IMPC). The purpose of this study was to evaluate the expression of MUC1/EMA and sLe(x) and to assess their diagnostic and prognostic value in patients with IMPC. Methods: The expression of sLe(x) and MUC1/EMA in 100 patients with IMPC and a control group of 89 patients with invasive ductal carcinoma not otherwise specified (IDC-NOS) were analyzed with IHC. Fresh tumor tissues were collected from patients with IMPC or IDC-NOS for primary culture and immundluorescence analysis. Results: The rate of nodal metastasis was higher in patients with IMPC than those with IDC-NOS, and IMPC cells tended to express more sLe(x) and MUCI/EMA in the cytomembranes (the stroma-facing surfaces of the micropapillary clusters) than IDC-NOS cells. In IMPC, high cytomembrane expression of sLe(x), hut not MUC1/EMA, indicated poor prognosis. In addition, among the 100 patients with IMPC, 10 patients had sLe(x)+/EMA- expression patterns, and 8 patients had sLe(x)-/EMA+ expression patterns. The primary IMPC cells were suspended, non adherent tumor cell clusters, whereas the primary WC cells were adherent tumor cells. Immunofluorescence analysis showed that MUC1/EMA and sLe(x) were co-expressed on the cytomembranes in IMPC cell clusters and in the cytoplasm in IDC-NOS cells. Conclusions: sLe(x) can be used as a prognostic indicator and can be combined with MUC1/EMA as a complementary diagnostic indicator to avoid missed IMPC diagnosis.

Automated summary

The study evaluated the expression of MUC1/EMA and sLe(x) in IMPC and IDC-NOS patients, finding a higher expression in IMPC cells and a correlation with nodal metastasis. The high cytomembrane expression of sLe(x) in IMPC indicated poor prognosis. Additionally, IMPC cells showed different expression patterns compared to IDC-NOS cells.