Introduction Patients with Barrett's (BE) associated oesophageal adenocarcinoma (OA), show strong expression of the mucin MUC1, but binding is not specific to dysplasia or cancer. Aberrant glycosylation of MUC1 (AG-MUC1) accompanies the development of cancer in most epithelial tumours, exposing peptides hidden on normal cells. Humanised antihuman milk-fat globule-1 (Hu-HMFG1) antibody binds one of these regions. This study assesses expression of AG-MUC1 in the squamous-metaplasia-dysplasia-OA sequence, in OA specimens with infiltrated nodes and in cancer cell lines.
Methods 34 paraffin embedded oesophageal tissue specimens were selected from patients with squamous (n=5), non-dysplastic BE (NDBE; n=3), low grade dysplasia (LGD; n=6), high grade dysplasia (HGD; n=9) and OA (n=11). 11 OA resection specimens with clear margins containing tumour and infiltrated nodes were also stained. Slides were immunostained with Hu-HMFG1 antibody and scored by an expert pathologist. Binding of HuHMFG1 to the cancer cell lines SKOV-3 (ovarian), MCF-7 (breast), OE-19, OE33 (oesophageal) and HT-29 (colon) was examined with flow cytometry using a secondary FITC conjugated antibody and analysed with FloJo.
Results AG-MUC1 was significantly expressed (>33% positively stained cells) in 22% of HGD and 36% of OA specimens. Non-significant mild staining was seen in NDBE (100%), LGD (33%), HGD (44%) and OA (64%). In 27% of OA and 43% of HGD, adjacent squamous epithelium also stained. In surgically resected OA's, 45% stained significantly for AG-MUC1 in primary tumour. Of these, 80% stained significantly in related lymph nodes. All OA resection margins were clear of significant staining. On flow cytometry, binding was noted on SKOV-3, MCF-7, OE-19 but not HT-29 or OE-33.
Conclusion This pilot study demonstrates AG-MUC1 to be upregulated in the BE metaplasia-dysplasia-OA sequence with significant staining limited to HGD and cancer. Although some squamous staining was noted, this was likely a field effect as no significant staining was noted in OA resection margins. In patients with significantly stained primary tumour, most had significant staining in infiltrated lymph nodes. Finally, with flow cytometry we identified the OA cell line, OE-19 expressed AG-MUC1 in preparation for in vitro studies. AG-MUC1 targeting with the antibody Hu-HMFG1 offers a novel strategy to target HGD and OA, including those patients presenting with metastatic disease.
Competing interests None declared.