MUC4 and ErbB2 expression in squamous cell carcinoma of the upper aerodigestive tract: correlation with clinical outcomes

Cell origin and genome profile difference of penoscrotum invasive extramammary Paget disease compared with its in situ counterpart

Penoscrotum extramammary Paget disease (pEMPD) is a rare cutaneous carcinoma with an unknown cell origin. pEMPD always presents as a tumor in situ with an indolent process, whereas some progress into invasive forms with more aggressive behavior. The in situ and invasive cases display different morphologies and biological behavior, and thus far, a relationship between these two components has not been demonstrated. Immunohistochemistry was used to disclose the immunotype of pEMPD, and the results revealed that invasive/in situ pEMPD possessed with some identical immunophenotypes such as CK7, P63, and CK10, which inferred the clonal relatedness. The variable expressions of GCDFP-15 and carcino embryonic antigen hinted that tumor cell origin might be an epidermal sweat gland in epiderma. In our cohort, invasive pEMPD presented increased expression of androgen receptor and decreased MUC5CA expression, and these two changes might bring to the shift of invasive phenotype. To better understanding the relationship between these distinct tumor forms, we performed whole exome sequencing testing to evaluate overlapping genomic alterations of six paired invasive/in situ pEMPDs. The results showed that missense mutation was the predominant mutation type, and C>T transition accounted for 65.1% in all SNP mutation. Among the top 20 differential genes obtained from the six paired invasive/in situ pEMPD analysis, MUC4 (one missense, one in frame del, and one multi-hit), AHNAK2 (two missense and one multi-hit), DOT1L (two missense and one multi-hit), and FRG1 (two missense and one-multi hit) mutations were most enriched in invasive pEMPDs, which postulated that these genes may play roles in the disease progression.

Integrative Analysis of MUC4 to Prognosis and Immune Infiltration in Pan-Cancer: Friend or Foe?

MUC4, a transmembrane mucin, plays important roles in epithelial renewal and differentiation. Recent studies suggest that MUC4 has been implicated in pancreatic cancer pathogenesis and is expressed in various normal and cancer tissues. The underlying features of MUC4 across various cancer types may allow us to ensure appropriate treatment and patient monitoring. However, the contributions of MUC4 to pan-cancer have not been well characterized. In this study, we investigated the expression pattern and prognostic value of MUC4 across multiple databases. We further explored genomic and epigenetic alterations of MUC4, its association with proliferation and metastasis, and the correlation with immune infiltration in different cancers. Our results characterized the distinct expression profile and prognostic values of MUC4 in pan-cancer. Through examining its association with genomic alteration, tumor proliferation, and metastasis, as well as tumor infiltration, we revealed multiple function effects of MUC4. MUC4 may influence prognosis, proliferation, metastasis, and immune response in opposite directions. In conclusion, our findings suggested the necessity to more carefully evaluate MUC4 as a biomarker and therapeutic target and develop the new antibodies for cancer detection and intervention.

MUC4 immunohistochemistry is useful in distinguishing epithelioid mesothelioma from adenocarcinoma and squamous cell carcinoma of the lung

The differential diagnosis of epithelioid mesothelioma from lung adenocarcinoma and squamous cell carcinoma requires the positive and negative immunohistochemical markers of mesothelioma. The IMIG guideline has suggested the use of Calretinin, D2–40, WT1, and CK5/6 as mesothelial markers, TTF-1, Napsin-A, Claudin 4, CEA as lung adenocarcinoma markers p40, p63, CK5/6, MOC-31 as squamous cell markers. However, use of other immunohistochemical markers is still necessary. We evaluated 65 epithelioid mesotheliomas, 60 adenocarcinomas, and 57 squamous cell carcinomas of the lung for MUC4 expression by immunohistochemistry and compared with the previously known immunohistochemical markers. MUC4 expression was not found in any of 65 cases of epithelioid mesothelioma. In contrast, MUC4 expression was observed in 50/60(83.3%) cases of lung adenocarcinoma and 50/56(89.3%) cases of lung squamous cell carcinoma. The negative MUC4 expression showed 100% sensitivity, 86.2% specificity and accuracy rate of 91.2% to differentiate epithelioid mesothelioma from lung carcinoma. The sensitivity, specificity, and accuracy of MUC4 are comparable to that of previously known markers of lung adenocarcinoma and squamous cell carcinoma, namely CEA, Claudin 4 and better than that of MOC-31. In conclusion, MUC4 immunohistochemistry is useful for differentiation of epithelioid mesothelioma from lung carcinoma, either adenocarcinoma or squamous cell carcinoma.

Prognostic Role of Mucin Antigen MUC4 for Cholangiocarcinoma: A Meta-Analysis

Background and Objective

Surgery carries the best hope for cure in the treatment of cholangiocarcinoma (CC), whereas surgical outcome is not fully satisfactory. Bio-molecular markers have been used to improve tumor staging and prognosis prediction. Mucin antigen MUC4 (MUC4) has been implicated as a marker for poor survival in various tumors. However, prognostic significance of MUC4 for patients with CC remains undefined. The aim of the present meta-analysis was to investigate the association between MUC4 expression and overall survival (OS) of patients with resected CC.

Methods

The meta-analysis was conducted in adherence to the MOOSE guidelines. PubMed, Embase databases, Cochrane Library and the Chinese SinoMed were systematically searched to identify eligible studies from the initiation of the databases to April, 2016. OSs were pooled by using hazard ratio (HR) with corresponding 95% confidence interval (CI). Random effect models were utilized because of the between-study heterogeneities.

Results

Five studies reporting on 249 patients were analyzed: 94 (37.75%) were in positive or high expression group and 155 (62.25%) in negative or low expression group. The pooled HR for positive or high expression group was found to be 3.04 (95% CI 2.25–4.12) when compared with negative or low expression group with slight between-study heterogeneities (I² 3.10%, P = 0.39). The result indicated that a positive or high expression level of MUC4 was significantly related to poor survival in patients with resected CC. A commensurate result was identified by sensitivity analysis. The main limitations of the present meta-analysis were the rather small size of the studies included and relatively narrow geographical distribution of population.

Conclusion

The result of this meta-analysis indicated that a positive or high expression level of MUC4 was significantly related to poor survival in patients with resected CC.

Expression of Mucin 4 in leukoplakia and oral squamous cell carcinoma: An immunohistochemical study

Background:

Mucins are large glycosylated proteins that act as a selective molecular barrier on the epithelial surface and engage themselves in morphogenetic signal transduction pathways. MUC4 (Mucin 4) is a transmembrane mucin, that protects and lubricates the mucous membranes of the human body and involves itself in various cellular functions like growth, differentiation and signaling. An aberrant expression of MUC4 has been demonstrated in various human cancers. A thorough literature survey shows very few studies about MUC4 expression in normal and cancerous oral mucosa.

Aim:

Our study aimed at investigating the expression pattern of MUC4 in normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma (OSCC) in an attempt to analyze its role played in oral carcinogenesis.

Materials and Methods:

Formalin-fixed paraffin-embedded tissues of five cases of normal tissue, 15 cases of leukoplakia, 10 cases of well-differentiated squamous cell carcinoma and 10 cases of moderately differentiated squamous cell carcinoma were retrieved from the archives of the department and MUC4 antigen was immunohistochemically localized.

Statistical Analysis:

The result was subjected to statistical analysis using Pearson's Chi-square test and an intergroup analysis was performed using one-way analysis of (ANOVA).

Results:

A total of 46.7% of leukoplakia and 70% of OSCC were stained positive with MUC4 antigen. Maximum intensity of staining was noted in well-differentiated OSCC. A steady increase in MUC4 staining was noted from normal oral tissues to leukoplakia to OSCC.

Conclusion:

The findings of the study suggest that MUC 4 plays a vital role in the pathogenesis of OSCC and can be regarded as a useful marker for oral dysplasia and OSCC.

Expression of MUC4 mucin is observed mainly in the intestinal type of intraductal papillary mucinous neoplasm of the pancreas

OBJECTIVES

This study aimed to examine expression profile of MUC4 in intraductal papillary mucinous neoplasm of the pancreas (IPMN).

METHODS

We performed immunohistochemistry (IHC) of MUC4 in 142 IPMNs, with evaluation of the specificity of 2 anti-MUC4 monoclonal antibodies, 8G7 and 1G8, in cancer cell lines.

RESULTS

Monoclonal antibody 8G7 showed a clear immunoreactivity, whereas MAb 1G8 did not show any immunoreactivity, in the Western blotting and IHC for human pancreatic carcinoma cell lines expressing MUC4 messenger RNA. However, IHC signals detected by both monoclonal antibodies were observed in the tissue specimens. The expression rates of MUC4/8G7 detected by MAb 8G7 and MUC4/1G8 detected by MAb 1G8 in the intestinal-type IPMNs were significantly higher than those in the gastric-type IPMNs. In the intestinal-type IPMNs, MUC4/8G7 was expressed mainly in the cytoplasm of the neoplastic cells, whereas MUC4/1G8 was expressed mainly at the cell apexes. Even in the gastric-type IPMNs with rare MUC4 expression in the low-grade dysplasia, both MUC4 expression rates increased when dysplasia advanced.

CONCLUSIONS

A significantly higher expression of MUC4 in intestinal-type IPMNs than in gastric-type IPMNs will be one of the biomarkers to discriminate between the intestinal-type IPMNs with high malignancy potential from gastric-type IPMNs with low malignancy potential.

MUC4 and MUC1 expression in adenocarcinoma of the stomach correlates with vessel invasion and lymph node metastasis: an immunohistochemical study of early gastric cancer

We have previously reported that MUC4 expression is a poor prognostic factor in various carcinomas. Our previous study also showed that MUC1 expression in gastric cancers, including the early and advanced stages is a poor prognostic factor. In the present study, the expression profiles of MUC4 and MUC1 were examined by immunohistochemistry (IHC) using two anti-MUC4 monoclonal antibodies (MAbs), 8G7 and 1G8, and anti-MUC1 MAb DF3 in 104 gastrectomy specimens of early gastric adenocarcinoma with submucosal invasion (pT1b2), including 197 histological subtype lesions. Before the IHC study of the human specimens, we evaluated the specificity of the two MAbs by Western blotting and IHC of two MUC4 mRNA expressing gastric cancer cell lines. MAb 8G7 reacted clearly, whereas MAb 1G8 did not show any reactivity, in either Western blotting or IHC. In the IHC of the gastric cancers, the expression rates of MUC4/8G7 detected by MAb 8G7, MUC4/1G8 detected by MAb 1G8 and MUC1/DF3 detected by MAb DF3 in well differentiated types (70%, 38/54; 67%, 36/54; 52%, 28/54) were significantly higher than those in poorly differentiated types (18%, 10/55; 36%, 20/55; 13%, 7/55) (P<0.0001; P = 0.0021; P<0.0001), respectively. The MUC4/8G7 expression was related with lymphatic invasion (r = 0.304, P = 0.033). On the other hand, the MUC4/1G8 expression was related with lymphatic invasion (r = 0.395, P = 0.001) and lymph node metastasis (r = 0.296, P = 0.045). The MUC1/DF3 expression was related with lymphatic invasion (r = 0.357, P = 0.032) and venous invasion (r = 0.377, P = 0.024). In conclusion, the expression of MUC4 as well as MUC1 in early gastric cancers is a useful marker to predict poor prognostic factors related with vessel invasion.

Expression of MUC1 and MUC4 in gallbladder adenocarcinoma

Background

Recent reports have indicated that overexpression of mucin (MUC) 1 and/or MUC4 correlates with the occurrence and progression of extra-hepatobiliary malignancy. In this study, we investigated the expression of MUC1 and MUC4 and their prognostic significance in gallbladder adenocarcinoma.

Methods

We examined 54 surgical gallbladder adenocarcinoma samples by immunohistochemistry for MUC1 and MUC4 expression. Staining was evaluated as a sum score of extent and intensity, dividing the samples into low and high expression groups.

Results

The low expression group for both MUC1 and MUC4 was 10 samples (18.5%), and the high expression group was 44 samples (81.5%). High MUC1 expression was significantly correlated with more differentiated tumors (p=0.033), whereas high expression of MUC4 correlated with negative nodal status (p=0.012). Other pathological features were not correlated with MUC expression. Multivariate cox regression analysis showed that neither MUC1 nor MUC4 expression correlated with survival.

Conclusions

Although there were some correlations found, a prognostic role for either MUC1 or MUC4 expression in gallbladder carcinoma was not identified in this study. Further investigation is required.

Prognostic significance of membrane-associated mucins 1 and 4 in gastric adenocarcinoma

Aberrant expression of mucins is likely associated with cancer biology as alterations in the expression and/or glycosylation patterns of various mucins have been noted. Expression of the mucin family in gastric cancers has been reported in numerous studies, but the results are conflicting. Therefore, we investigated the potential use of mucin (MUC)1 and 4 as prognostic markers in gastric cancer according to histological subtype. Three-hundred and sixty-five gastric adenocarcinoma patients who underwent surgical resection were selected for this study. Among the 365 gastric cancer samples tested here, 34% consisted of early gastric cancer and 66% were advanced. In terms of location, 68.7% of the cohort had intestinal-type cancer and 30.7% had diffuse-type. We constructed tissue microarrays with formalin-fixed paraffin-embedded blocks of gastric cancer and these micro-arrays were evaluated for phenotypic expression of MUC1/4 using monoclonal antibodies. Two-hundred and ninety-two patients (92.7%) were positive for MUC1 and 216 (60.5%) were positive for MUC4. MUC1 expression was not correlated with any other clinicopathological variables such as age, gender, depth of invasion, lymph node metastasis, Lauren classification or recurrence. However, loss of MUC4 expression was significantly correlated with recurrence (p=0.033). MUC4 expression was also significantly correlated with better disease-free survival (p=0.049) and particularly in the intestinal-type (p=0.018). Our present findings demonstrated that loss of MUC4 expression can be used as a prognostic marker in gastric cancer. Loss of MUC4 expression is a prognostic indicator of increased recurrence and poor disease-free survival in patients with gastric cancer.

Recent advances in mucin immunohistochemistry in salivary gland tumors and head and neck squamous cell carcinoma

This review focuses on the immunohistochemical expression of members of the MUC-type mucin family in salivary gland tumors and head and neck squamous cell carcinomas (HNSCC). Information is available on changes in the expression levels and distribution profiles of MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7 in tumors of the salivary glands; and of MUC1, MUC2 and MUC4 in HNSCC. In salivary gland tumors the expression patterns of MUC2, MUC3, MUC5AC and MUC6 appear to be very closely correlated with the histopathological tumor type indicating their potential use to improve diagnostic accuracy in salivary gland neoplasia. Some MUC-type mucins have emerged as valuable prognostic indicators in pleomorphic adenoma, mucoepidermoid carcinoma and HNSCC. Nine antibodies directed against different MUC1 antigens have thus far been examined in HNSCC of which monoclonal antibodies DF3, HMFG-1 and Ma695 have shown significant correlations with disease outcome. The importance of taking the specific anti-MUC antibody into consideration when comparing the results of different studies on MUC expression in salivary gland tumors and HNSCC is also highlighted in this review.

What role do mucins have in the development of laryngeal squamous cell carcinoma? A systematic review

Mucins are the dominant component in the protective mucus layer on mucosal surfaces including the larynx. Hence, they are part of the first line of defence against external stimuli including effect of smoking in the larynx. We asked whether existing published evidence supported the hypothesis that alteration in mucins expression/production is related to the laryngeal neoplastic process. The objective of this study is to review published evidence for mucins having an important role in normal laryngeal physiology and the development of laryngeal squamous cell carcinoma (SCC). We aimed to review all available literature on mucins in the larynx in order to develop hypotheses to be tested by future research. Thereby, new potential means of prevention and treatment of laryngeal cancer may be developed. A systematic search of all published literature was conducted. Systematic searches were done in the following databases: AMED, BNI, EMBASE, HMIC, MEDLINE, PsycINFO, CINAHL and HEALTH BUSINESS ELITE from their respective inception up to 11 February 2011. The following keywords were used in combination: mucin, larynx and squamous cell carcinoma. Altogether, 53 studies were identified; 43 studies were excluded following screening of the titles and abstracts. Full text manuscripts for ten studies were obtained for detailed evaluation and five studies were included in this review. No single study fulfilled all relevant criteria. Based on the included studies, we now know that MUC1 is definitely expressed in SCC larynx. However, there is no definitive evidence to suggest that MUC1 and MUC2 are aberrantly expressed in SCC larynx as compared to normal larynx. Further studies using the best available detection technique to detect MUC1, MUC2 and other possible relevant mucins i.e., MUC4 on adequate numbers of normal and SCC specimens are needed to confirm the findings of this review.

Prognostic value of mucin 4 expression in colorectal adenocarcinomas

BACKGROUND

Mucin 4 (MUC4) is aberrantly expressed in colorectal adenocarcinomas (CRCs) but its prognostic value is unknown.

METHODS

Archival tissue specimens collected from 132 CRC patients who underwent surgical resection without presurgery or postsurgery therapy were evaluated for expression of MUC4 by using a mouse monoclonal antibody and horseradish peroxidase. MUC4 expression levels were correlated with clinicopathologic features and patient survival. Survival was estimated by both univariate Kaplan-Meier and multivariate Cox regression methods.

RESULTS

In both normal colonic epithelium and CRCs, MUC4 staining was localized primarily in the cytoplasm. The optimal immunostaining cutoff value (>or=75% positive cells and an immunostaining score>or=2.0), which was derived by using the bootstrap method, was used to categorize CRCs into groups of high expression (33 of 132 patients; 25%) or low expression (99 of 132 patients; 75%). Patients who had early stage tumors (stages I and II) with high MUC4 expression had a shorter disease-specific survival (log-rank; P=.007) than patients who had with low expression. Patients who had advanced-stage CRCs (stages III and IV) did not demonstrate such a difference (log-rank; P=.108). Multivariate regression models that were generated separately for patients with early stage and advanced-stage CRC confirmed that increased expression of MUC4 was an independent indicator of a poor prognosis only for patients who had early stage CRCs (hazard ratio, 3.77; 95% confidence interval, 1.46-9.73).

CONCLUSIONS

The current results indicated that increased MUC4 expression is a predictor of poor survival in CRC, specifically for patients who have early stage tumors.

Muc4/MUC4 functions and regulation in cancer

The membrane mucin MUC4 (human) is abundantly expressed in many epithelia, where it is proposed to play a protective role, and is overexpressed in some epithelial tumors. Studies on the rat homologue, Muc4, indicate that it acts through anti-adhesive or signaling mechanisms. In particular, Muc4/MUC4 can serve as a ligand/modulator of the receptor tyrosine kinase ErbB2, regulating its phosphorylation and the phosphorylation of its partner ErbB3, with or without the involvement of the ErbB3 ligand neuregulin. Muc4/MUC4 can also modulate cell apoptosis via multiple mechanisms, both ErbB2 dependent and independent. Muc4/MUC4 expression is regulated by multiple mechanisms, ranging from transcriptional to post-translational. The roles of MUC4 in tumors suggest that it may be valuable as a tumor marker or target for therapy.

The membrane-bound mucins: From cell signalling to transcriptional regulation and expression in epithelial cancers

The membrane-bound mucins belong to an ever-increasing family of O-glycoproteins. Based on their structure and localization at the cell surface they are thought to play important biological roles in cell-cell and cell-matrix interactions, in cell signalling and in modulating biological properties of cancer cells. Among them, MUC1 and MUC4 mucins are best characterized. Their altered expression in cancer (overexpression in the respiratory, gastro-intestinal, urogenital and hepato-biliary tracts) indicates an important role for these membrane-bound mucins in tumour progression, metastasis, cancer cell resistance to chemotherapeutics drugs and as specific markers of epithelial cancer cells. Some mechanisms responsible for MUC1 and MUC4 role in tumour cell properties have been deciphered recently. However, much remains to be done in order to understand the molecular mechanisms and signalling pathways that control the expression of membrane-bound mucins during the different steps of tumour progression toward adenocarcinoma and evaluate their potential as prognostic/diagnostic markers and as therapeutic tools. In this review we focus on the molecular mechanisms and signalling pathways known to control the expression of membrane-bound mucins in cancer. We will discuss the mechanisms of regulation at the promoter level (including genetic and epigenetic modifications) that may be responsible for the mucin altered pattern of expression in epithelial cancers.

Deregulation of MUC4 in gastric adenocarcinoma: potential pathobiological implication in poorly differentiated non-signet ring cell type gastric cancer

MUC4 is a large, heavily glycosylated transmembrane mucin, that is implicated in the pathogenesis of various types of cancers. To date, no extensive study has been done to check the expression and functional significance of MUC4 in different types of gastric adenocarcinomas. Here, we report the expression profile of MUC4 in gastric adenocarcinomas and its function in poorly differentiated gastric non-signet ring cell carcinoma (non-SRCC) type cells. Immunohistochemical analysis using tissue microarray (TMA) showed a significant difference in MUC4 expression between normal adjacent (n=45) and gastric adenocarcinoma (n=83; P<0.001). MUC4 expression was not associated with tumour type, stage or with the degree of differentiation. To gain further insight into the significance of MUC4 expression in gastric non-SRCC cells, MUC4 was ectopically expressed in AGS, a poorly differentiated gastric non-signet ring cell line. The MUC4 overexpressing cells (AGS-MUC4) showed a significant increase (P<0.005) in cell motility and a decrease in cellular aggregation as compared with the vector-transfected cells. Furthermore, in vivo tumorigenicity analysis revealed that animals transplanted with the MUC4 overexpressing cells (AGS-MUC4) had a greater incidence of tumours (83%) in comparison to empty vector control (17%). In addition, the expression of MUC4 resulted in enhanced expression of total cellular ErbB2 and phosphorylated ErbB2. In conclusion, our results showed that MUC4 is overexpressed in gastric adenocarcinoma tissues, and that it has a role in promoting aggressive properties in poorly differentiated gastric non-SRCC cells through the activation of the ErbB2 oncoprotein.

MUC4, a multifunctional transmembrane glycoprotein, induces oncogenic transformation of NIH3T3 mouse fibroblast cells

Numerous studies have established the association of MUC4 with the progression of cancer and metastasis. An aberrant expression of MUC4 is reported in precancerous lesions, indicating its early involvement in the disease process; however, its precise role in cellular transformation has not been explored. MUC4 contains many unique domains and is proposed to affect cell signaling pathways and behavior of the tumor cells. In the present study, to decipher the oncogenic potential of MUC4, we stably expressed the MUC4 mucin in NIH3T3 mouse fibroblast cells. Stable ectopic expression of MUC4 resulted in increased growth, colony formation, and motility of NIH3T3 cells in vitro and tumor formation in nude mice when cells were injected s.c. Microarray analysis showed increased expression of several growth-associated and mitochondrial energy production-associated genes in MUC4-expressing NIH3T3 cells. In addition, expression of MUC4 in NIH3T3 cells resulted in enhanced levels of oncoprotein ErbB2 and its phosphorylated form (pY(1248)-ErbB2). In conclusion, our studies provide the first evidence that MUC4 alone induces cellular transformation and indicates a novel role of MUC4 in cancer biology.

Structure and Function of the Cell Surface (Tethered) Mucins

Cell surface mucins are large transmembrane glycoproteins involved in diverse functions ranging from shielding the airway epithelium against pathogenic infection to regulating cellular signaling and transcription. Although hampered by the relatively recent characterization of cell surface mucins and the difficulties inherent in working with molecules of their size, numerous studies have placed the tethered mucins in the thick of normal and diseased lung physiology. This review focuses on the three best-characterized cell surface mucins expressed in the respiratory tract: MUC1, MUC4, and MUC16.

Structure, evolution, and biology of the MUC4 mucin

Mucins are high-molecular-weight glycoproteins and are implicated in diverse biological functions. MUC4, a member of transmembrane mucin family, is expressed in airway epithelial cells and body fluids like saliva, tear film, ear fluid, and breast milk. In addition to its normal expression, an aberrant expression of MUC4 has been reported in a variety of carcinomas. Among various potential domains of MUC4, epidermal growth factor (EGF) -like domains are hypothesized to interact with and activate the ErbB2 receptors, suggesting an intramembrane-growth factor function for MUC4. The heavily glycosylated tandem repeat domain provides the structural rigidity to the extended extracellular region. MUC4, by virtue of its extended structure, serves as a barrier for some cell-cell and cell-extracellular matrix interactions and as a potential reservoir for certain growth factors. An intricate relationship between MUC4 and growth factor signaling is also reflected in the transcriptional regulation of MUC4. The MUC4 promoter has binding sites for different transcription factors, which are responsible for the regulation of its expression in different tissues. The interferon-gamma, retinoic acid, and transforming growth factor-beta signaling pathways regulate MUC4 expression in a partially interdependent manner. Taken together, all of these features of MUC4 strongly support its role as a potential candidate for diagnostic and therapeutic applications in cancer and other diseases.

Chemoprevention of squamous cell carcinoma of the head and neck

PURPOSE OF REVIEW

The aim of this article is to summarize progress in understanding of the biology of squamous cell carcinoma of the head and neck and of trials to prevent malignant conversion of oral premalignant lesions and the development of second primary tumors in those already treated for squamous cell carcinoma of the head and neck.

RECENT FINDINGS

The understanding of squamous cell carcinoma of the head and neck biology is rapidly evolving. Clinical trials for chemoprevention are involving more diverse regimens, following disappointing results of retinoid monotherapy. In-vitro and animal studies form the rationale for the next generation of studies, employing combination, synergistic treatments.

SUMMARY

Based on trial data to date, no recommendation for intervention with a chemopreventive agent can be made. It is clear, however, that smoking cessation is an effective intervention for preventing oral premalignant lesions and second primary tumors. Promising trials are being conducted and designed currently. The future of this area of study will involve rational choice of multidrug regimens based on current understanding of the biology of squamous cell carcinoma of the head and neck.

MUC4 expression in non-small cell lung carcinomas: relationship to tumor histology and patient survival

CONTEXT

Mucin 4 (MUC4) is a high-molecular-weight membrane-bound glycoprotein that is expressed in the foregut before epithelial differentiation. It is found in normal adult airway epithelium, non-small cell lung carcinoma (NSCLC) and in other human malignancies independent of mucus secretion. Although its tissue distribution has been studied, its utility in predicting prognosis in NSCLC is unknown.

OBJECTIVE

To evaluate the relationship between MUC4 overexpression and long-term survival in patients with NSCLC.

DESIGN

Immunohistochemical staining for MUC4 was performed on formalin-fixed, paraffin-embedded tissue samples from 343 cases of NSCLC arranged in a high-density tissue microarray. Information about long-term survival and tumor stage was collected for all patients. Semiquantitative assessment of MUC4 staining was correlated with survival (Kaplan-Meier analysis).

RESULTS

MUC4 was frequently expressed in adenocarcinomas (151/187 [81%]), squamous cell carcinomas (69/ 88 [78%]), adenosquamous carcinomas (6/8 [75%]), and large cell carcinomas (33/60 [55%]). High levels of expression (combined score, 2+/3+) for MUC4 were more characteristic of adenocarcinomas (126/187 [68%]) and adenosquamous carcinomas (6/8 [75%]) than of squamous cell carcinomas (46/88 [52%]) and large cell carcinomas (17/60 [28%]) (P < .001). In patients with stage I and II adenocarcinoma, there was a trend toward longer patient survival with higher levels of MUC4 immunoreactivity compared with lower levels (P = .11).

CONCLUSION

MUC4 expression is common in pulmonary adenocarcinomas and may indicate a more favorable prognosis in early-stage adenocarcinomas.

Human MUC4 mucin induces ultra-structural changes and tumorigenicity in pancreatic cancer cells

MUC4 is a type-1 transmembrane glycoprotein and is overexpressed in many carcinomas. It is a heterodimeric protein of 930 kDa, composed of a mucin-type subunit, MUC4α, and a membrane-bound growth factor-like subunit, MUC4β. MUC4 mRNA contains unique 5′ and 3′ coding sequences along with a large variable number of tandem repeat (VNTR) domain of 7–19 kb. A direct association of MUC4 overexpression has been established with the degree of invasiveness and poor prognosis of pancreatic cancer. To understand the precise role of MUC4 in pancreatic cancer, we engineered a MUC4 complementary DNA construct, mini-MUC4, whose deduced protein (320 kDa) is comparable with that of wild-type MUC4 (930 kDa) but represents only 10% of VNTR. Stable ectopic expression of mini-MUC4 in two human pancreatic cancer cell lines, Panc1 and MiaPaCa, showed that MUC4 minigene expression follows a biosynthesis and localisation pattern similar to the wild-type MUC4. Expression of MUC4 resulted in increased growth, motility, and invasiveness of the pancreatic cancer cells in vitro. Ultra-structural examination of MUC4-transfected cells showed the presence of increased number and size of mitochondria. The MUC4-expressing cells also demonstrated an enhanced tumorigenicity in an orthotopic xenograft nude mice model, further supporting a direct role of MUC4 in inducing the cancer properties. In conclusion, our results suggest that MUC4 promotes tumorigenicity and is directly involved in growth and survival of the cancer cells.

Regulation of the human mucin MUC4 by taurodeoxycholic and taurochenodeoxycholic bile acids in oesophageal cancer cells is mediated by hepatocyte nuclear factor 1alpha

MUC4 (mucin 4) is a membrane-bound mucin overexpressed in the early steps of oesophageal carcinogenesis and implicated in tumour progression. We previously showed that bile acids, main components of gastro-oesophageal reflux and tumour promoters, up-regulate MUC4 expression [Mariette, Perrais, Leteurtre, Jonckheere, Hemon, Pigny, Batra, Aubert, Triboulet and Van Seuningen (2004) Biochem. J. 377, 701-708]. HNF (hepatocyte nuclear factor) 1alpha and HNF4alpha transcription factors are known to mediate bile acid effects, and we previously identified cis-elements for these factors in MUC4 distal promoter. Our aim was to demonstrate that these two transcription factors were directly involved in MUC4 activation by bile acids. MUC4, HNF1alpha and HNF4alpha expressions were evaluated by immunohistochemistry in human oesophageal tissues. Our results indicate that MUC4, HNF1alpha and HNF4alpha were co-expressed in oesophageal metaplastic and adenocarcinomatous tissues. Studies at the mRNA, promoter and protein levels indicated that HNF1alpha regulates endogenous MUC4 expression by binding to two cognate cis-elements respectively located at -3332/-3327 and -3040/-3028 in the distal promoter. We also showed by siRNA (small interfering RNA) approach, co-transfection and site-directed mutagenesis that HNF1alpha mediates taurodeoxycholic and taurochenodeoxycholic bile acid activation of endogenous MUC4 expression and transcription in a dose-dependent manner. In conclusion, these results describe a new mechanism of regulation of MUC4 expression by bile acids, in which HNF1alpha is a key mediator. These results bring new insights into MUC4 up-regulation in oesophageal carcinoma associated with bile reflux.

Mucin Genes (MUC2, MUC4, MUC5AC, and MUC6) Detection in Normal and Pathological Endometrial Tissues

Changes in the composition and physical properties of the mucous gel covering the endometrial surface are detected during the menstrual cycle and in pathological conditions. The aim of this study is to analyze the expression patterns of the 11p15 secreted mucins, MUC2, MUC5AC, and MUC6, and the membrane-bound mucin MUC4 in proliferative and secretory normal endometrium, simple and complex hyperplasia, and endometrial adenocarcinoma. A total of 98 samples, 19 of normal endometrium (11 proliferative and 8 secretor), 44 of endometrial hyperplasia (23 simple, 21 complex), and 35 of endometrial endometrioid adenocarcinomas were analyzed by immunohistochemical techniques using specific antimucin antibodies. In the endometrial proliferative glandular epithelium, only MUC4 is detected (36.3% cases). During the secretory phase, increased levels of MUC2 are found (37.5%), whereas MUC4 is less detected (12.5%). In simple hyperplasia, higher levels of mucins are expressed in the endometrial glands: MUC2 is detected in 8.7%, MUC4 in 43.4%, and MUC5AC and MUC6 in 13% of the samples, whereas in complex hyperplasia, decreased levels of mucin expression are found: MUC2 and MUC5AC are not detected, and MUC4 (28.5%) and MUC6 (20.4%) are positive. In endometrial adenocarcinoma, MUC4 is highly detected (77.1%) and increased levels of MUC5AC and MUC6 are found (61.7% and 48.5%), whereas MUC2 is poorly detected (8.5%). These findings suggest that during endometrial neoplasic transformation, increased levels of MUC4, MUC5AC, and MUC6 are detected, whereas MUC2 is only significantly detected in the secretory endometrium.

MUC4 expression and its relation to ErbB2 expression, apoptosis, proliferation, differentiation, and tumor stage in non-small cell lung cancer (NSCLC)

There is a peptide sequence homology between the gene product of human MUC4 and rat Muc4/sialomucin complex (SMC). Each contains a transmembrane subunit with two epidermal growth factor (EGF)-like domains that act as ligand for ErbB2. MUC4 and ErbB2 mediate intracellular signaling pathways that are linked to repression of apoptosis and either to proliferation or to differentiation of tumor cells. This study investigates the expression of human MUC4 in neoplastic and corresponding non-neoplastic tissues, and the relation of MUC4 expression in neoplastic tissues to ErbB2 expression, apoptosis, proliferation, differentiation, and tumor stage in a series of 100 non-small cell lung carcinomas (NSCLCs). MUC4 and ErbB2 expressions and cell proliferation (PCNA) were shown using immunohistochemistry. Apoptotic index (AI) and tumor differentiation were determined by morphologic criteria. All the non-neoplastic bronchial tissues and 85% of NSCLCs showed MUC4 expression. MUC4 expression was found to be higher in neoplastic than in non-neoplastic tissues (Yates correction p: 0.0006). MUC4 expression was inversely correlated with AI (p=0.0002) and was correlated with ErbB2 expression (p=0.022), but not with PCNA counts and tumor stage. Our results indirectly suggest that MUC4, in association with ErbB-2, might be involved in the repression of apoptosis and differentiation rather than proliferation in tumor cells of NSCLCs.

IL-4 induced MUC4 enhancement in respiratory epithelial cells in vitro is mediated through JAK-3 selective signaling

BACKGROUND

Recent studies have identified MUC4 mucin as a ligand for activation of ErbB2, a receptor tyrosine kinase that modulates epithelial cell proliferation following epithelial damage in airways of asthmatics. In this study, we investigated the potential role of IL-4, one of the Th2 inflammatory cytokines persistent in asthmatic airways, in regulating MUC4 expression using a cell line NCI-H650.

METHODS

Real time PCR analysis was performed to determine concentration and time dependent effects of IL-4 upon MUC4 expression. Nuclear run on experiments were carried out to explore potential transcriptional modulation. Western blotting experiments using a monoclonal antibody specific to ASGP-2 domain of MUC4 were performed to analyze MUC4 glycoprotein levels in plasma membrane fractions. To analyze potential signal transduction cascades, IL-4 treated confluent cultures were co-incubated, separately with a pan-JAK inhibitor, a JAK-3 selective inhibitor or a MEK-1, 2 (MAPK) inhibitor at various concentrations before MUC4 transcript analysis. Corresponding transcription factor activation was tested by western blotting using a monoclonal p-STAT-6 antibody.

RESULTS

MUC4 levels increased in a concentration and time specific fashion reaching peak expression at 2.5 ng/ml and 8 h. Nuclear run on experiments revealed transcriptional enhancement. Corresponding increases in MUC4 glycoprotein levels were observed in plasma membrane fractions. Pan-JAK inhibitor revealed marked reduction in IL-4 stimulated MUC4 levels and JAK3 selective inhibitor down-regulated MUC4 mRNA expression in a concentration-dependent fashion. In accordance with the above observations, STAT-6 activation was detected within 5 minutes of IL-4 stimulus. No effect in MUC4 levels was observed on using a MAPK inhibitor.

CONCLUSION

These observations signify a potential role for IL-4 in MUC4 up-regulation in airway epithelia.

Aberrant expression of transmembrane mucins, MUC1 and MUC4, in human prostate carcinomas

BACKGROUND

Mucins are considered important markers for early diagnosis and targeted therapy due to their aberrant and unique expression pattern during malignant progression of carcinomas. Recent findings have provided substantial evidence for the involvement of transmembrane mucins, MUC1 and MUC4, in altered cell signaling, tumor growth, and metastasis.

METHODS

Immunohistochemical analyses were performed on prostate tumor tissues for expression profiling of the two transmembrane mucins, MUC1 and MUC4. In cancer cell lines, the expression was studied by RT-PCR and immunoblot analyses. Cells were treated with DNA-methylase and histone-deacetylase inhibitors to examine the implication of epigenetic mechanism(s) in MUC4 regulation.

RESULTS

The expression of MUC4 was significantly down regulated in prostate cancer tissues (n=38, P=0.0026) compared to normal/benign prostatic hyperplastic regions. A faint to moderate staining was observed in 26.3% cases of cancer, while 84.2% cases of adjacent normal were positive for MUC4 with moderate to strong staining in most cases. Similar observations were made in immortalized normal prostate epithelial and cancer cell lines. MUC1 also showed a reduced expression in prostate tumor tissues; however, its expression was comparable in all normal prostate epithelial and cancer cell lines. Interestingly, we also found that epigenetic mechanism(s) might be implicated in MUC4 gene silencing.

CONCLUSIONS

Our data suggest that MUC4 downregulation may be of significance for diagnostic applications in prostate cancer.