Interference of mucin 1 inhibits progression of colon carcinoma by repression of Wnt/β-catenin signaling

The Roles of Transmembrane Mucins Located on Chromosome 7q22.1 in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common types of cancers. It is associated with a poor prognosis and high mortality. The role of mucins (MUCs) in colon tumorigenesis is unclear, but it might be significant in the progression of malignancy. Some mucins, such as MUC1 and MUC13, act as oncogenes, whereas others, such as MUC2 and MUC6, are tumor suppressors. However, there are still mucins with unidentified roles in CRC. In this review, we discuss the reported roles of mucins in CRC. Moreover, we review the capability of the mucin family to serve as a sensitive and specific histopathological marker for the early diagnosis of CRC. Lastly, the role of mucin genes clustered on chromosome 7q22 in CRC and other cancers is also discussed.

MUC1 gene silencing inhibits proliferation, invasion, and migration while promoting apoptosis of oral squamous cell carcinoma cells

The aim of the present study is to investigate the role of RNA interference in the inhibition of MUC1 gene expression in occurrence and metastasis of oral squamous cell carcinoma (OSCC) and its in-depth mechanisms. The OSCC and normal oral mucosa tissues, as well as normal oral epithelial cell line HOK and OSCC cell line SCC-4, Cal-27, TSCCA, Tca8113 were obtained to detect the expression of MUC1. Slug expression in OSCC and normal oral mucosa tissues was also determined. The OSCC cells were grouped to investigate the role of MUC1 gene silencing on proliferation, DNA replication, cell cycle distribution, apoptosis, colony formation ability, epithelial-mesenchymal transition (EMT), invasion, and migration of OSCC cells. We first found higher positive rate of MUC1 and Slug expression in OSCC tissues. Next, it was determined that higher expression of MUC1 was found in OSCC tissues and cells. Furthermore, silencing of MUC1 declined Slug expression, inhibited the proliferation, DNA replication, cell cycle progression, and EMT while inducing apoptosis of OSCC cells. Our study suggests that overexpression of MUC1 is found in OSCC, and MUC1 gene silencing could inhibit the proliferation, invasion, and migration while inducing apoptosis of OSCC cells.

MUC1/KL-6 expression confers an aggressive phenotype upon myeloma cells

The sialic glycoprotein, MUC1, is known to be involved in the pathogenesis of various types of cancers. KL-6 is one of the surface antigens of MUC1 and also a marker of interstitial pneumonitis. A fraction of patients with myeloma (3.9%) have elevated serum KL-6 levels without any evidence of interstitial pneumonitis and their myeloma cells have high MUC1 expression. We established a myeloma cell line designated EMM1 from a patient with multiple myeloma accompanied with elevated serum KL-6. EMM1 cells expressed high levels of MUC1 compared with other myeloma cell lines. Knockdown of MUC1 in EMM1 cells induced cell cycle arrest during S phase and apoptosis, suggesting that the MUC1 expression is involved in accelerated growth of EMM1 cells. RNA-seq analysis suggests that MUC1 expression activates k-ras and TNFα-induced NFκB pathways in EMM1 cells. We injected EMM1 cells subcutaneously into Rag2^-/-Jak3^-/- Balb/c mice to establish a mouse xenograft model. These mice had aggressive tumor growth that was accompanied by high serum KL-6 levels. In addition, MUC1 knockdown in EMM1 cells led to inhibited tumor growth. These findings demonstrate that MUC1 serves as a potential target for developing drugs for treatment of patients with KL-6⁺ myeloma, and EMM1 cells and EMM1-engrafted mice are useful tools for the development of such novel agents.

MUC1 expression in colorectal carcinoma: Clinicopathological correlation and prognostic significance

INTRODUCTION

MUC1 overexpression has been linked to cancer development and has been associated with a higher stage at diagnosis and presence of lymph node or distant metastases. However, its prognostic significance is still unclear. We aimed to evaluate the relationship between MUC1 expression and prognosis of colorectal carcinoma.

MATERIALS AND METHODS

Immunohistochemical expression of MUC1 in 96 colorectal carcinomas with analysis of potential prognostic influence.

RESULTS

55.2% of patients were women and the mean age was 65.9 years. Tumors were more frequently located in rectum or sigmoid colon (60.4% and 21.9%). Most tumors were T3 (60.3%). 36.9% of patients showed lymph node metastases and 30.2% showed distant metastasis at the time of diagnosis. MUC1 was intensely positive in 46% and negative in 37.9% of tumors. Overall, 61% of patients recurred and 40.4% died during follow-up. 58.5% of tumors of surviving patients were intensely positive for MUC1 and 29.5% were negative, as compared with 28.5% (intense positivity) and 51.4% (negativity) in the group of patients who died (p=0.022). 65% of tumors of patients without recurrences showed intense positivity for MUC1 and 23% of them were negative as compared with 33.9% (intense positivity) and 47% (negativity) in the group of patients who recurred (p=0.019).

CONCLUSIONS

Loss of MUC1 expression was more frequent in cases with disease recurrence or death, as compared with patients with stable disease, in whom intense positivity was more frequently seen. These findings disagree with the majority of previous studies, indicating the need for further investigation.

Mucins and Wnt/β-catenin signaling in gastrointestinal cancers: an unholy nexus

The Wnt/β-catenin signaling pathway is indispensable for embryonic development, maintenance of adult tissue homeostasis and repair of epithelial injury. Unsurprisingly, aberrations in this pathway occur frequently in many cancers and often result in increased nuclear β-catenin. While mutations in key pathway members, such as β-catenin and adenomatous polyposis coli, are early and frequent occurrences in most colorectal cancers (CRC), mutations in canonical pathway members are rare in pancreatic ductal adenocarcinoma (PDAC). Instead, in the majority of PDACs, indirect mechanisms such as promoter methylation, increased ligand secretion and decreased pathway inhibitor secretion work in concert to promote aberrant cytosolic/nuclear localization of β-catenin. Concomitant with alterations in β-catenin localization, changes in mucin expression and localization have been documented in multiple malignancies. Indeed, numerous studies over the years suggest an intricate and mutually regulatory relationship between mucins (MUCs) and β-catenin. In the current review, we summarize several studies that describe the relationship between mucins and β-catenin in gastrointestinal malignancies, with particular emphasis upon colorectal and pancreatic cancer.

Significance of MUC1 expression in biopsy specimens of submucosal invasive gastric carcinoma: The association with lymph node metastasis

Mucin 1, cell surface associated (MUC1) is a tumor-associated glycoprotein that has been reported to have an important role in lymphatic invasion and metastasis. The present study aimed to investigate the significance of MUC1 expression in endoscopic biopsy specimens of submucosal invasive gastric carcinomas and the association with lymph node metastasis. The clinicopathological features of 144 cases of surgically resected submucosal invasive gastric carcinomas and their paired endoscopic biopsy specimens were reviewed. Immunohistochemical staining for MUC1 was performed for the 144 endoscopic biopsy specimens. Positive MUC1 expression was identified in 70 (49%) cases. In addition, univariate analysis revealed that MUC1 expression was significantly associated with the presence of poorly-differentiated (P=0.001) and poorly-cohesive (P=0.015) carcinoma cells, undifferentiated type by Japanese classification (P<0.001), diffuse type of Lauren classification (P<0.001) and lymph node metastasis (P=0.024). By multivariate analysis, diffuse type of Lauren classification (P<0.001) and lymph node metastasis (P=0.035) were identified as independent factors for MUC1 expression. Furthermore, MUC1 expression (P=0.007), tumor size (P=0.018) and lymphatic invasion (P<0.001) were demonstrated to be independent factors for lymph node metastasis under multivariate analysis. In conclusion, the results of the present study indicated that positive MUC1 expression in endoscopic biopsy specimens may be a predictive factor of lymph node metastasis in submucosal invasive gastric carcinoma.