[MUC1 (EMA): A key molecule of carcinogenesis?]

Mucin expression, epigenetic regulation and patient survival: A toolkit of prognostic biomarkers in epithelial cancers

Twenty mucin genes have been identified and classified in two groups (encoding secreted and membrane-bound proteins). Secreted mucins participate in mucus formation by assembling a 3-dimensional network via oligomerization, whereas membrane-bound mucins are anchored to the outer membrane mediating extracellular interactions and cell signaling. Both groups have been associated with carcinogenesis progression in epithelial cancers, and are therefore considered as potential therapeutic targets. In the present review, we discuss the link between mucin expression patterns and patient survival and propose mucins as prognosis biomarkers of epithelial cancers (esophagus, gastric, pancreatic, colorectal, lung, breast or ovarian cancers). We also investigate the relationship between mucin expression and overall survival in the TCGA dataset. In particular, epigenetic mechanisms regulating mucin gene expression, such as aberrant DNA methylation and histone modification, are interesting as they are also associated with diagnosis or prognosis significance. Indeed, mucin hypomethylation has been shown to be associated with carcinogenesis progression and was linked to prognosis in colon cancer or pancreatic cancer patients. Finally we describe the relationship between mucin expression and non-coding RNAs that also may serve as biomarkers. Altogether the concomitant knowledge of specific mucin-pattern expression and epigenetic regulation could be translated as biomarkers with a better specificity/sensitivity performance in several epithelial cancers.

Clinical effect of MUC1 and its relevance to BRAF V600E mutation in papillary thyroid carcinoma: a case-control study

AIM

To investigate the clinical effects of MUC1 on papillary thyroid cancer (PTC) and explore the relationship between MUC1 expression and BRAF mutation.

METHODS

The data of 69 patients subjected to fine-needle aspiration biopsy in our hospital and 486 patient data downloaded from The Cancer Genome Atlas (TCGA) database were used. Univariate and multivariate analyses were performed.

RESULTS

The results on the 486 patients recorded in the TCGA indicated that high MUC1 expression was independently related to BRAF mutation, lymph node metastasis (LNM), and unifocal type. In the 69 fine-needle aspiration biopsy patients with PTC, high MUC1 expression was significantly related to LNM and extrathyroid extension (ETE). The result of Pearson's correlation coefficient showed that BRAF mutation and MUC1 expression were moderately correlated. Moreover, in the subgroup with low MUC1 expression, the patients with BRAF mutation had higher ETE frequency and LNM than those without BRAF mutation. In the subgroup with BRAF mutation, patients with high MUC1 expression exhibited higher ETE frequency than those with low MUC1 expression, and high MUC1 expression occurred in older patients. In the subgroup with BRAF wild-type mutation, patients with high MUC1 expression had a higher incidence of ETE and LNM than those with low expression.

CONCLUSION

We demonstrated that the MUC1 is an important oncogene in PTC and may have great significance on therapeutic cancer vaccine development.

Evaluation of peptide designing strategy against subunit reassociation in mucin 1: A steered molecular dynamics approach

Subunit reassociation in mucin 1, a breast cancer tumor marker, is reported as one of the critical factors for its cytoplasmic activation. Inhibition of its heterodimeric association would therefore result in loss of its function and alter disease progression. The present study aimed at evaluating peptide inhibitor designing strategies that may serve as antagonist against this receptor-ligand alliance. Several peptides and their derivatives were designed based on native residues, subunit interface, hydrogen bonding and secondary structure. Docking studies with the peptides were carried on the receptor subunit and their binding affinities were evaluated using steered molecular dynamics simulation and umbrella sampling. Our results showed that among all the different classes of peptides evaluated, the receptor based peptide showed the highest binding affinity. This result was concurrent with the experimental observation that the receptor-ligand alliance in mucin 1 is highly specific. Our results also show that peptide ligand against this subunit association is only stabilized through native residue inter-protein interaction irrespective of the peptide structure, peptide length and number of hydrogen bonds. Consistency in binding affinity, pull force and free energy barrier was observed with only the receptor derived peptides which resulted in favorable interprotein interactions at the interface. Several observations were made and discussed which will eventually lead to designing efficient peptide inhibitors against mucin 1 heterodimeric subunit reassociation.

Reversed polarity of the glandular epithelial cells in micropapillary carcinoma of the large intestine and the EMA/MUC1 immunostain

Micropapillary carcinoma of the colon and rectum is associated with an adverse prognosis. This tumour type displays reverse polarity of the tumour cells and is stated to be characterised by an inside-out epithelial membrane antigen (EMA)/MUC1 staining. Nine cases of primary colorectal carcinoma and one omental metastasis were studied by means of immunohistochemistry, using antibodies to detect EMA, MUC1, MUC2, MUC3, MUC5AC, MUC6, CD10, CA125, carcinoembryonic antigen (CEA). The inside-out pattern staining with EMA/MUC1 ranged from diffuse circumferential through focal and partial to negative, but in some cases CEA, MUC3 and CD10 also showed this pattern staining, sometimes more clearly than did EMA or MUC1. The reverse polarity of colorectal micropapillary carcinomas is sometimes better visualised by immunostains other than EMA/MUC1.

MUC1 expression in papillary thyroid carcinoma is associated with BRAF mutation and lymph node metastasis; the latter is the most important risk factor of relapse

BACKGROUND

The incidence of papillary thyroid carcinoma (PTC) has increased over the past 30 years in Western countries. PTC is usually associated with a good prognosis, but there is a wide range of aggressiveness, and some patients develop distant metastasis and/or resistance to standard treatment. Early identification of these high-risk tumors is a current challenge for appropriate patient management. MUC1 expression has been studied previously in thyroid cancer, but its prognostic value remains controversial. Here, we correlated MUC1 expression in PTC with clinical and pathological features and with the presence of the BRAF(V600E) mutation.

METHODS

We performed a clinical and morphological analysis of 190 thyroid tumors (95 PTCs and 95 adenomas). MUC1 immunohistochemistry was carried out on a tissue microarray using different antibodies. The presence of the BRAF(V600E) mutation was investigated by pyrosequencing. MUC1 mRNA levels were assessed by quantitative reverse transcription polymerase chain reaction on a subset of PTC.

RESULTS

MUC1 expression was observed in 49% of PTCs and was found to correlate with the presence of papillary architecture, a stromal lymphoid infiltrate, aggressive histological subtypes, extrathyroidal extension, lymph node metastasis, nuclear pseudoinclusions, lymphovascular invasion, and the presence of the BRAF(V600E) mutation (p<0.0001). MUC1 was abundant in nuclear pseudoinclusions. Multivariate analysis showed a strong association of MUC1 expression with the presence of the BRAF(V600E) mutation and lymph node metastasis (p<0.0001). Lymph node metastasis was the most important risk factor of relapse.

CONCLUSIONS

Our study shows an association between MUC1 expression and the presence of the BRAF(V600E) mutation in PTC. Analysis of MUC1 expression could improve the risk stratification of PTCs.

Should EMT of Cancer Cells Be Understood as Epithelial-Myeloid Transition?

Cancer cells express epithelial markers, and when progressing in malignancy they may express markers of the mesenchymal cell type. Therefore an epithelial-mesenchymal transition of the cancer cells is assumed. However the mesenchymal markers can equally well be interpreted as myeloid markers since they are common in both types of cell lineages. Moreover, cancer cells express multiple specific markers of the myeloid lineages thus giving rise to the hypothesis that the transition of cancer cells may be from epithelial to myeloid cells and not to mesenchymal cells. This interpretation would better explain why cancer cells, often already in their primary cancer site, frequently show properties common to those of macrophages, platelets and pre-/osteoclasts.

Determination of paraneoplastic autoimmune responses by tumor cell biology and intratumoral IFN-alpha/IL-12 in breast cancer patients

A wide variety of cancer types has been associated with paraneoplastic autoimmune disorders and with the induction of autoimmunity against several autoantigens, among them self-antigens that are also expressed by tumor cells. This raises the question of autoimmune disorders as a result of immune reactions to the tumor. To date, however, requirements for the generation of autoimmune reactions in cancer patients remain largely unclear. In this study, we characterized conditions in altogether 131 patients, which determine autoimmune responses in primary breast cancer patients. We used ex vivo IFN-γ EliSpot assays against autologous tumor or skin lysates to evaluate tumor- and auto-reactive T-cells (TCs) in the bone marrow (BM) as well as ELISA, ECLIA, and turbidimetric immunoassays for the detection of auto-reactive antibodies in the peripheral blood and compared results to intratumoral cytokine concentrations and pathobiological features of the primary tumor tissue. We here demonstrate a significant correlation between anti-tumor BMTC responses and cellular autoimmune reactivity in primary breast cancer patients (P = 0.002). Humoral autoimmune reactions, however, were negatively correlated with anti-tumor TC immunity (P = 0.039). We observed auto-reactive BMTCs especially in patients with well-differentiated, hormone receptor-positive carcinomas (P = 0.009). Furthermore, elevated concentrations of intratumoral IFN-α significantly correlated with the induction of cellular autoimmune reactivity (P = 0.0002), while humoral autoimmune reactions correlated with increased levels of intratumoral IL-12 (P = 0.04). Altogether, these data indicate a significant role of the tumor microenvironment and particularly that of IFN-α and IL-12 in the induction of systemic autoimmune responses and imply that the primary tumor tissue represents an integral site of autoimmune regulation in cancer patients.

Anti-MUC1 aptamers: radiolabelling with (99m)Tc and biodistribution in MCF-7 tumour-bearing mice

INTRODUCTION

Aptamers previously selected against the protein core (AptA) or the tumour glycosylated (AptB) MUC1 glycoprotein have been conjugated to MAG2 and labelled with (99m)Tc, for the potential use as radiopharmaceuticals for diagnostic imaging of breast cancer.

METHODS

The conjugation was achieved in high yield using standard peptide coupling reactions between an amino modification on the aptamer and the activated carboxylic group on the ligands. The retention of the affinity of the MAG2 modified AptA for the MUC1 protein core was confirmed using a fluorescent intercalator displacement binding assay. The labelled aptamers were separated from free (99m)Tc using ultrafiltration and monitored by high-performance liquid chromatography at all stages, to ensure that only radiolabelled aptamers were produced. The biodistribution properties of the two aptamer-radionuclide conjugates were analysed in MCF-7 tumour bearing mice and compared.

RESULTS

Efficient and convenient labelling of the two aptamers with (99m)Tc was achieved as the last step of the synthesis (post-conjugation labelling). Both the aptamer-chelator conjugates had strong (99m)Tc binding properties and the resulting complexes were stable in vivo, both in terms of nuclease degradation and leaking of the metal. The radiolabelled aptamers showed a high renal clearance and a high uptake in the intestine.

CONCLUSIONS

AptA and AptB have been successfully conjugated in high yield to the ligand MAG2 and labelled with (99m)Tc. The radiolabelled aptamers showed different tumour uptake and clearance, but will require further development prior to diagnostic use.

MUC-1 mucin in normal human salivary glands detected by HMFG-1 and HMFG-2 monoclonal antibodies

The aim of this study was to determine the immunoexpression of normal salivary gland cells using two human milk fat globule membrane protein antibodies (HMFG-1 and HMFG-2). Paraffin-embedded, 5 microm-thick slides from parotid and submandibular gland tissues were cut and immunostained with monoclonal antibodies HMFG-1 and HMFG-2 against MUC1 protein. HMFG antigens were found in secretory epithelial cells and ductal cells lining the striated and intercalated ducts in the intraductal secretion material, and sometimes in the myoepithelial cells. Our results suggest that HMFG-1 and HMFG-2 proteins may play a role in normal salivary gland function, mainly in the manufacturing and secretion of saliva.