ErbB2 and its ligand Muc4 (sialomucin complex) in rat lacrimal gland

MUC4 enhances gemcitabine resistance and malignant behaviour in pancreatic cancer cells expressing cancer-associated short O-glycans

Pancreatic ductal adenocarcinoma (PDAC) is highly lethal. MUC4 (mucin4) is a heavily glycosylated protein aberrantly expressed in PDAC and promotes tumorigenesis via an unknown mechanism. To assess this, we genetically knocked out (KO) MUC4 in PDAC cells that did not express and did express truncated O-glycans (Tn/STn) using CRISPR/Cas9 technology. We found that MUC4 knockout cells possess less tumorigenicity in vitro and in vivo, which was further reduced in PDAC cells that express aberrant overexpression of truncated O-glycans. Also, MUC4KO cells showed a further reduction of epidermal growth factor receptors (ErbB) and their downstream signaling pathways in truncated O-glycan expressing PDAC cells. Tn-MUC4 specific 3B11 antibody inhibited MUC4-induced ErbB receptor and its downstream signaling cascades. MUC4 knockout differentially regulates apoptosis and cell cycle arrest in branched and truncated O-glycan expressing PDAC cells. Additionally, MUC4KO cells were found to be more sensitive to gemcitabine treatment. They possessed the upregulated expression of hENT1 and hCNT3 compared to parental cells, which were further affected in cells with aberrant O-glycosylation. Taken together, our results indicate that MUC4 enhances the malignant properties and gemcitabine resistance in PDAC tumors that aberrantly overexpress truncated O-glycans via altering ErbB/AKT signaling cascades and expression of nucleoside transporters, respectively.

Effects of adjuvant omega-3 fatty acid supplementation on dry eye syndrome following cataract surgery: A randomized clinical trial

PURPOSE

To investigate the effect of omega-3 polyunsaturated fatty acid supplement on qualitative and quantitative subjective (ocular surface disease index [OSDI]) and objective (Schirmer's test, tear break up time [TBUT], and tear osmolarity) dry eye indices after cataract surgery.

METHODS

In this randomized clinical study, 61 eyes of 48 patients complaining of new onset dry eye symptoms after phacoemulsification were enrolled. Subjects were randomly allocated into two groups using urn randomization. Controls received conventional treatment. The treatment group received omega-3 dietary supplement in addition to conventional therapy.

RESULTS

There was no significant difference between the control and treatment groups in pre-treatment indices of Schirmer (3.50 ± 3.13 and 2.96 ± 3.39, respectively, P = 0.582), TBUT (6.67 ± 1.36 and 4.87 ± 2.22, respectively, P = 0.687), osmolarity (316.66 ± 8.50 and 315.4 ± 17.06, respectively, P = 0.906), and OSDI (32.99 ± 19.03 and 35.32 ± 18.99, respectively, P = 0.635). Mean pre-treatment OSDI in the control group was 32.99 ± 19.03, which improved significantly after treatment to 25.43 ± 14.49 (P = 0.003). The mean pre-treatment OSDI in the treatment group was 35.32 ± 18.99 (range: 7.5-77.77), which improved significantly after treatment to 16.31 ± 13.72 (range: 2.77-47.22) (P < 0.001). OSDI improvement was significantly higher in the treatment group than the control group (P = 0.026). TBUT improved in both the control and treatment groups after treatment (P < 0.001). However, TBUT was affected significantly more in the treatment group compared with the control group (P = 0.038). Mean tear film osmolarity in the control group was 316.67 ± 8.50 (range: 308-325), which improved insignificantly after treatment to 311.33 ± 6.35 (range: 304-315) (P = 0.157). Mean pre-treatment tear film osmolarity in the treatment group was 315.40 ± 17.06 (range: 279-340), which improved significantly after treatment to 296.90 ± 14.39 (range: 260-310) (P < 0.001). Also, post-treatment Schirmer results between the two groups were not statistically significant (P = 0.155).

CONCLUSION

Omega-3 dietary supplements have an additive effect on tear film indices of patients with dry eye syndrome after phacoemulsification.

A field test of Web-based screening for dry eye disease to enhance awareness of eye problems among general Internet users: a latent strategy to promote health

Background

A Web-based self-check system including a brief questionnaire would seem to be a suitable tool for rapid disease screening.

Objective

The purpose of this preliminary study was to test a Web-based self-screening questionnaire for drawing attention to dry eye disease among general Internet users and identifying those with a higher risk of developing the condition.

Methods

A survey website was launched and used to recruit participants from general Internet users. In the first phase, volunteers were asked to complete a Web-based self-screening questionnaire containing 12 questions on dry eye symptoms. The second phase focused on the respondents who reported five or more dry eye symptoms and expressed their intention to seek medical attention. These participants performed the Schirmer test, for evaluating tear production, and completed a paper-based lifestyle questionnaire to provide relevant background data.

Results

Of the 1689 visitors to the website, 980 (58.0%) volunteers completed the Web-based self-screening questionnaire. Among these, 355 (36.2%) respondents reported five or more dry eye symptoms. Then, 99 (27.9%) of the symptomatic participants performed the Schirmer test and completed the paper-based lifestyle questionnaire. Out of these, 32 (32.2%) had abnormal tear production (≤5 mm).

Conclusions

The proposed Web-based self-screening questionnaire seems to be a promising tool for raising awareness of dry eye disease among general Internet users and identifying those with a higher risk of developing the condition, although further research is needed to validate its effectiveness.

Changes in the tear film and ocular surface after cataract surgery

PURPOSE

To evaluate changes in corneal sensitivity, tear film function, and ocular surface stability in patients after cataract surgery.

METHODS

This hospital-based prospective randomized trial included 48 eyes from 30 patients who underwent phacoemulsification. Slit-lamp examination, Schirmer test 1 (ST1), and measurement of corneal sensitivity and tear film breakup time (BUT) were performed for all patients 1 day before and 1 day, 1 month, and 3 months after surgery. In addition, conjunctival impression cytology from the temporal region of the conjunctiva was simultaneously performed.

RESULTS

Corneal sensitivity at the center and temporal incision sites had decreased significantly at 1 day postoperatively (P = .021, P < .001). However, the sensitivity had returned to almost the preoperative level 1 month postoperatively. The mean postoperative ST1 results were no different from preoperative values. On the other hand, BUT results had decreased significantly at 1 day postoperatively (P = .01) but had returned to almost the preoperative level 1 month postoperatively. Mean goblet cell density (GCD) had decreased significantly at 1 day, 1 month, and 3 months postoperatively (P < .001). In addition, decrease in GCD and cataract operative time were highly correlated (r² = 0.65).

CONCLUSIONS

The decrease in GCD, which was correlated with operative time, had not recovered at 3 months after cataract surgery. Therefore, microscopic ocular surface damage during cataract surgery seems to be one of the pathogenic factors that cause ocular discomfort and dry eye syndrome after cataract surgery.

EGFR/HER-targeted therapeutics in ovarian cancer

Despite decades of research and evolving treatment modalities, survival among patients with epithelial ovarian cancer has improved only incrementally. During this same period, the development of biologically targeted therapeutics has improved survival for patients with diverse malignancies. Many of these new drugs target the human epidermal growth factor receptor (EGFR/HER/ErbB) family of tyrosine kinases, which play a major role in the etiology and progression of many carcinomas, including epithelial ovarian cancer. While several HER-targeted therapeutics are US FDA approved for the treatment of various malignancies, none have gained approval for the treatment of ovarian cancer. Here, we review the published literature on HER-targeted therapeutics for the treatment of ovarian cancer, including novel HER-targeted therapeutics in various stages of clinical development, as well as the challenges that have limited the use of these inhibitors in clinical settings.

Not all lacrimal epithelial cells are created equal-heterogeneity of the rabbit lacrimal gland and differential secretion

AIMS

To test the hypotheses that some epithelial cells in the rabbit lacrimal gland (LG) are mucin-secreting cells that are also particularly rich in aquaporin 5 (AQP5) and sodium potassium ATPase β(1) subunit (NKAβ(1)), LG-secreted mucins contribute to the total mucin pool in tear film, and that the rabbit LG is a heterogenic gland where proteins secreted in response to different agonists are varied.

MATERIALS AND METHODS

LGs were obtained from adult female rabbits and processed for paraffin sections for hematoxylin and eosin (HE) staining, periodic acid-Schiff (PAS), mucicarmine, and Alcian blue (pH 0.4, 1.0, and 2.5) for the detection of mucins. Serial sections were used for immunohistochemistry (IHC) and PAS. LG lysates and fluids were assayed by dot blot for detection of mucins, and by SDS-PAGE to detect differences in protein profiles of LG fluids stimulated by different agonists.

RESULTS

HE staining demonstrated that the LG is a heterogeneous gland where most epithelial cells are serous, while all duct cells are mucous cells. Some acini and individual acinar cells within serous acini are also mucous or seromucous cells and these cells are particularly rich in AQP5 and NKAβ(1). Dot blot assay showed the presence of mucins in the LG fluids. The protein profiles of LG fluids from pilocarpine, phenylephrine, and isoproterenol varied significantly, particularly in the mid range.

CONCLUSIONS

Our data indicated that the rabbit LG is a heterogeneous gland that is composed of both serous and mucin-secreting cells, and mucins produced by the LG contribute to the mucin pool in the tear film. The heterogeneity of the rabbit LG supports the notion of differential secretion, i.e. the volume and composition of the LG fluids vary depending on various circumstances in the ocular surface and the body's needs.

Appraisal of patient-reported outcome instruments available for randomized clinical trials in dry eye: revisiting the standards

Clinical signs in dry eye (DE) often underestimate the severity of the condition, correlating poorly with symptoms and the impact on patients' health-related quality of life (HRQL). Patient-reported outcome (PRO) questionnaires are therefore essential to accurately evaluate the health status of DE patients and the severity of their condition. A comprehensive evaluation of HRQL in addition to clinical signs and visual function is necessary to fully characterize the impact of DE on patients' health. Growing interest in PRO measures and their implementation in clinical trials has resulted in more formal guidance on the design and properties of these instruments. To be scientifically sound and accepted by regulatory authorities, an instrument's development process and its appropriateness for use in the target population, its psychometric properties and responsiveness must be described. To address the recent health authority guidance, this review discusses the design, development methodology, and performance of currently available PRO instruments for DE.

Development and validation of the impact of dry eye on everyday life (IDEEL) questionnaire, a patient-reported outcomes (PRO) measure for the assessment of the burden of dry eye on patients

Objective

To develop and validate a comprehensive patient-reported outcomes instrument focusing on the impact of dry eye on everyday life (IDEEL).

Methods

Development and validation of the IDEEL occurred in four phases: 1) focus groups with 45 dry eye patients to develop a draft instrument, 2) item generation, 3) pilot study to assess content validity in 16 patients and 4) psychometric validation in 210 subjects: 130 with non-Sjögren's keratoconjunctivitis sicca, 32 with Sjögren's syndrome and 48 controls, and subsequent item reduction.

Results

Focus groups identified symptoms and the associated bother, the impact of dry eye on daily life and the patients' satisfaction with their treatment as the central concepts in patients' experience of dry eye. Qualitative analysis indicated that saturation was achieved for these concepts and yielded an initial 112-item draft instrument. Patients understood the questionnaire and found the items to be relevant indicating content validity. Patient input, item descriptive statistics and factor analysis identified 55 items that could be deleted. The final 57-item IDEEL assesses dry eye impact constituting 3 modules: dry eye symptom-bother, dry eye impact on daily life comprising impact on daily activities, emotional impact, impact on work, and dry eye treatment satisfaction comprising satisfaction with treatment effectiveness and treatment-related bother/inconvenience. The psychometric analysis results indicated that the IDEEL met the criteria for item discriminant validity, internal consistency reliability, test-retest reliability and floor/ceiling effects. As expected, the correlations between IDEEL and the Dry Eye Questionnaire (a habitual symptom questionnaire) were higher than between IDEEL and Short-Form-36 and EuroQoL-5D, indicating concurrent validity.

Conclusion

The IDEEL is a reliable, valid and comprehensive questionnaire relevant to issues that are specific to dry eye patients, and meets current FDA patient-reported outcomes guidelines. The use of this questionnaire will provide assessment of the impact of dry eye on patient dry eye-related quality of life, impact of treatment on patient outcomes in clinical trials, and may aid in treatment effectiveness evaluation.

Anxiety and depression in patients with dry eye syndrome

PURPOSE

This study aimed to determine whether patients with dry eye syndrome [DES] have more symptoms of anxiety and depression than controls without DES.

METHODS

In this case-control study, the sample consisted of 89 DES subjects (13 diagnosed with Sjögren's syndrome [SS]) and 73 control subjects. Each subject was diagnosed as having DES or was chosen as a control subject by an ophthalmologist. The Zung Self Rating Anxiety Scales (SAS), Zung Self Rating Depression Scales (SDS), and Ocular Surface Disease Index (OSDI) were administered to all subjects. Scores of SAS and SDS, measuring level of anxiety and depression symptoms, were compared between the DES group and the control group. Correlations with other health status measures were conducted.

RESULTS

The SAS and SDS scores of the DES group were significantly higher than the control group (P < 0.001, P < 0.001). The prevalence of DES subjects with anxiety or depression symptoms was significantly higher than in the control group (P = 0.003, P < 0.001). In the DES group, SAS scores were found to be correlated with OSDI and educational level. SDS scores were found to be correlated with OSDI. Neither SAS nor SDS scores were correlated with age, sex, household income, tear break up time (BUT), Schirmer Test 1 (S1T), corneal fluorescein staining (FL), or visual acuity.

CONCLUSION

Anxiety and depression are correlated with DES, demonstrating that DES is an important public health problem that merits increased attention and research.

Non-invasive in vivo measurement of the tear film using spatial autocorrelation in a live mammal model

Tear film stability and its interaction with the corneal surface play an important role in maintaining ocular surface integrity and quality of vision. We present a non-invasive technique to quantify the pre-corneal tear film thickness. A cMOS camera is used to record the interference pattern produced by the reflections from multiple layers of the tear film Principles of spatial autocorrelation are applied to extract the frequency of the periodic patterns in the images. A mathematical model is developed to obtain the thickness of the tear film from the spatial autocorrelation image. The technique is validated using micro-fabricated thin parylene films. We obtained repeatable and precise measurement on a live rabbit model (N = 6). We obtained an average value of 10.2µm and standard deviation of, SD = 0.3 (N = 4). We measured one rabbit infected with HSV-1 virus that had a baseline tear film thickness of 4.7µm.

The Annual Cost of Dry Eye Syndrome in France, Germany, Italy, Spain, Sweden and the United Kingdom Among Patients Managed by Ophthalmologists

OBJECTIVES

To estimate the annual cost associated with the management of dry eye patients by ophthalmologists in France, Germany, Italy, Spain, Sweden, and the United Kingdom (UK) from the perspective of the healthcare systems in the respective countries.

METHODS

Published epidemiological and healthcare resource use data attributable to dry eye syndrome was supplemented with information obtained from interviewing ophthalmologists in the six countries.

RESULTS

The estimated prevalence of dry eye syndrome among patients reporting to ophthalmologists was less than 0.1% in all six countries. The total annual healthcare cost of 1,000 dry eye syndrome sufferers managed by ophthalmologists ranged from 0.27 million US dollars (95% CI: 0.20 US dollars; 0.38 million US dollars) in France to 1.10 million US dollars (95% CI: 0.70 US dollars; 1.50 million US dollars) in the UK. A large proportion of dry eye patients either self-treat or are managed by their general practitioner. Hence, our analysis reflects the prevalence and costs of those patients severe enough to warrant treatment by an ophthalmologist.

CONCLUSIONS

Given the limitations of the available economic evidence and our data sources, dry eye syndrome does not appear to impose a direct burden to the health care expenditure in the countries investigated. However, given that many dry eye sufferers self-treat with over-the-counter artificial tears and other medications, data which our study did not capture, the true societal costs of dry eye syndrome, borne by both patient and government, are likely to be higher.

MUC4 activates HER2 signalling and enhances the motility of human ovarian cancer cells

The mucin MUC4 is a high molecular weight transmembrane glycoprotein. It consists of a mucin-type subunit (MUC4alpha) and a transmembrane growth factor-like subunit (MUC4beta). The mucin MUC4 is overexpressed in many epithelial malignancies including ovarian cancer, suggesting a possible role in the pathogenesis of these cancers. In this study, we investigated the functional role of MUC4 in the human ovarian cancer cell line SKOV3. The mucin MUC4 was ectopically expressed by stable transfection, and its expression was examined by western blot and confocal microscopy analyses. The in vitro studies demonstrated an enhanced motility of MUC4-expressing SKOV3 cells compared with the vector-transfected cells. The mucin MUC4 expression was associated with apparent changes in actin organisation, leading to the formation of microspike, lammelopodia and filopodia-like cellular projections. An enhanced protein expression and activation of HER2, a receptor tyrosine kinase, was also seen, although no significant change was observed in HER-2 transcript levels in the MUC4-transfected SKOV3 cells. Reciprocal co-immunoprecipitation revealed an interaction of MUC4 with HER2. Further, the MUC4-overexpressing SKOV3 cells exhibited an increase in the phosphorylation of focal adhesion kinase (FAK), Akt and ERK, downstream effectors of HER2. Taken together, our findings demonstrate that MUC4 plays a role in ovarian cancer cell motility, in part, by altering actin arrangement and potentiating HER2 downstream signalling in these cells.

Muc4 is required for activation of ErbB2 in signet ring carcinoma cell lines

Signet-ring cell carcinoma is one of the most malignant tumors, classified histologically as a poorly differentiated adenocarcinoma. The ErbB2/ErbB3 complex is often constitutively activated, which suggests that the ErbB2/ErbB3 signaling pathway may be important for malignancy of this tumor. However, the mechanism underlying this activation has not been understood. Here, we show that ErbB2 and Muc4 bind in signet ring carcinoma cells, which was not seen in highly differentiated adenocarcinoma cell lines. ErbB3 was suggested to be a substrate of ErbB2 because knockdown of ErbB2 resulted in less phosphorylation of ErbB3. Inhibition of expression of Muc4 at the cell surface by the treatment of the cells with benzyl-GalNac, an inhibitor of mucin secretion, blocked phosphorylation of ErbB3, suggesting that activity of ErbB2 depends on the expression of Muc4. These results supply the biochemical backgrounds in recent studies suggesting the contribution of Muc4 in the tumorigenesis.

Cell and molecular biology of human lacrimal gland and nasolacrimal duct mucins

The old concept that the lacrimal gland is only a serous gland has been superseded by the finding that lacrimal acinar cells are able to produce mucins--high-molecular-weight proteins--the major mass being carbohydrates with the common feature of tandem repeats of amino acids rich in serine, threonine, and proline in the central domain of the mucin core peptide. At the ocular surface, maintenance of the tear film, lubrication, and provision of a pathogen barrier on the epithelia, conjunctiva, and cornea have been shown to be facilitated by mucins that are present in membrane-anchored (lining epithelial cells) or secreted (goblet cells) form. Also in the lacrimal gland, both membrane-anchored (MUCs 1, 4, and 16) and secreted (MUCs 5B and 7) mucins have been identified. The lacrimal gland is the main contributor to the aqueous portion of the tear film. It is part of the lacrimal apparatus that comprises, together with the lacrimal gland, the paired lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, which collects the tear fluid and conveys it into the nasal cavity. In this review, the latest information regarding mucin function in the human lacrimal gland and the human efferent tear ducts is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes, and certain disease states such as the pathogenesis of dry eye, dacryostenosis, and dacryolith formation.

Comparing the discriminative validity of two generic and one disease-specific health-related quality of life measures in a sample of patients with dry eye

OBJECTIVE

The purpose of this study was to compare the discriminative properties of two generic health-related quality of life (QoL) instruments (SF-36 and EQ-5D) and a newly developed disease-specific patient-reported outcomes instrument (Impact of Dry Eye on Everyday Life (IDEEL)) to distinguish between different levels of dry eye severity.

METHODS

Assessment of 210 people: 130 with non-Sjogren's Keratoconjunctivitis Sicca (non-SS KCS), 32 with Sjögren's Syndrome (SS) and 48 controls; comparison of SF-36, EQ-5D, and IDEEL age-adjusted data by dry eye severity levels. Severity was assessed based on diagnosis (non-SS KCS, SS, control), patient-report (none, very mild, mild, moderate, severe, extremely severe) and clinician-report (none, mild, moderate, severe).

RESULTS

Discriminative validity results were consistent for all instruments. Significant differences between severity levels were found with most SF-36 scales (P < 0.05), all EQ-5D scales (P < 0.05), and all IDEEL scales (P < 0.0001), except for Treatment Satisfaction. IDEEL scales consistently outperformed the generic QoL measures regardless of the severity criterion used. Most SF-36 scales outperformed the EQ-5D QoL scale, but the EQ-5D visual analog scale outperformed the SF-36 scales, except for General Health Perceptions.

CONCLUSIONS

The disease-specific IDEEL scales are better able to discriminate between severity levels than the majority of the generic QoL scales. Preliminary evidence demonstrates that the IDEEL will be sensitive to QoL changes over time, although further testing in controlled longitudinal studies is needed.

Tr�nendr�senassoziierte Muzine

BACKGROUND

The secretory cells of the human lacrimal gland show a PAS-positive reaction in cytochemical staining procedures, suggesting the production of mucous substances. Recently, these substances were differentiated according to modern molecular classifications.

RESULTS

Expression studies detected mRNA for MUC1, MUC4, MUC5AC, MUC5B, MUC6, and MUC7, whereas MUC2 transcripts were absent in all samples investigated. Immunohistochemistry revealed membrane-bound MUC1 at the apical surface of acinar cells, MUC5AC associated with goblet cells of excretory ducts, MUC5B and MUC7 in the cytoplasm of acinar cells, and MUC7 also in epithelial cells of excretory ducts. MUC2 (RT-PCR negative) and MUC6 (RT-PCR positive) were not detectable by immunohistochemistry. MUC4 mRNA was present in all samples from patients treated for dry eye but only in 6 of 30 glands from individuals who did not receive treatment with artificial tears. Dot-blot analyses clearly revealed increased amounts of MUC4, MUC5AC and MUC5B in the glands of elderly women who received treatment for dry eye as compared to the remaining samples.

CONCLUSION

These results confirm that the human lacrimal gland synthesizes a spectrum of mucins, some of which might be involved in the pathophysiology of dry eye syndrome.

Changes in the tear film and ocular surface from dry eye syndrome

Dry eye syndrome (DES) refers to a spectrum of ocular surface diseases with diverse and frequently multiple aetiologies. The common feature of the various manifestations of DES is an abnormal tear film. Tear film abnormalities associated with DES are tear deficiency, owing to insufficient supply or excessive loss, and anomalous tear composition. These categorizations are artificial, as in reality both often coexist. DES disrupts the homeostasis of the tear film with its adjacent structures, and adversely affects its ability to perform essential functions such as supporting the ocular surface epithelium and preventing microbial invasion. In addition, whatever the initial trigger, moderate and severe DES is characterized by ocular surface inflammation, which in turn becomes the cause and consequence of cell damage, creating a self-perpetuating cycle of deterioration. Progress has been made in our understanding of the aetiology and pathogenesis of DES, and these advances have encouraged a proliferation of therapeutic options. This article aims to amalgamate prevailing ideas of DES development, and to assist in that, relevant aspects of the structure, function, and production of the tear film are reviewed. Additionally, a synopsis of therapeutic strategies for DES is presented, detailing treatments currently available, and those in development.

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

OBJECTIVES/HYPOTHESIS

Expression of the membrane mucin MUC4 has been associated with a variety of malignancies, including squamous cell carcinoma of the upper aerodigestive tract. MUC4 modulates cell signaling pathways as an intramembrane ligand of ErbB2. The hypotheses of the study were that MUC4 expression would correlate with ErbB2 expression and that MUC4 expression would correlate with clinical outcomes in squamous cell carcinoma of the upper aerodigestive tract.

STUDY DESIGN

Retrospective chart review was combined with immunohistochemical analysis of paraffin-embedded tumor specimens from patients treated with initial definitive surgical resection at an academic tertiary care medical center.

METHODS

MUC4 and ErbB2 receptor expression was localized by immunohistochemical studies using archival formalin-fixed and paraffin-embedded tissue. A limited number of fresh-frozen tissues were further analyzed by Western blot. Clinical outcomes and histopathological parameters were determined by retrospective chart review and correlated with immunohistochemical findings.

RESULTS

One hundred fifty-four patients were analyzed with a median follow-up of 12 months among 54 patients who died and 49 months among 100 surviving patients. Membrane expression of MUC4 and ErbB2 was seen in 12% and 13% of tumors, respectively. MUC4 expression was not correlated with pathological grade. A significant correlation was found between MUC4 expression and ErbB2 expression. Multivariate survival analyses revealed that patients whose tumors exhibited MUC4 membrane expression had statistically significant improvement in survival and longer time to recurrence compared with patients whose tumors did not express MUC4 as defined by immunohistochemical staining patterns. No correlations between ErbB2 expression and survival or recurrence were observed.

CONCLUSION

Patients with tumors that retain MUC4 expression exhibit improved survival and decreased recurrence in squamous cell carcinoma of the upper aerodigestive tract. Correlations between MUC4 expression patterns and ErbB2 expression are also observed, suggesting that MUC4-ErbB2 mediated cell signaling pathways may provide insights into this clinical result.

Control of mucin production by ocular surface epithelial cells

Multiple species of mucins are synthesized and secreted by corneal and conjunctival epithelial cells. These mucins are vital components of the tear film protecting the ocular surface from the external environment by providing a physical and chemical barrier. The release of mucins must be tightly regulated as both mucin overproduction and underproduction cause ocular surface disorders. Mucin production can be regulated by controlling mucin synthesis, mucin release, or proliferation of the cells that produce the mucin. This review will focus on the evidence demonstrating the control of the mechanisms responsible for production of mucins, their secretion, and corneal and conjunctival epithelia cell proliferation. By understanding these mechanisms under normal conditions, treatments can be designed for diseases of the mucous production of the ocular surface.