Mucinous bronchioloalveolar carcinomas display a specific pattern of mucin gene expression among primary lung adenocarcinomas

Selection of potential targets for stratifying congenital pulmonary airway malformation patients with molecular imaging: is MUC1 the one?

Currently there is a global lack of consensus about the best treatment for asymptomatic congenital pulmonary airway malformation (CPAM) patients. The somatic KRAS mutations commonly found in adult lung cancer combined with mucinous proliferations are sometimes found in CPAM. For this risk of developing malignancy, 70% of paediatric surgeons perform a resection for asymptomatic CPAM. In order to stratify these patients into high- and low-risk groups for developing malignancy, a minimally invasive diagnostic method is needed, for example targeted molecular imaging. A prerequisite for this technique is a cell membrane bound target. The aim of this study was to review the literature to identify potential targets for molecular imaging in CPAM patients and perform a first step to validate these findings.A systematic search was conducted to identify possible targets in CPAM and adenocarcinoma in situ (AIS) patients. The most interesting targets were evaluated with immunofluorescent staining in adjacent lung tissue, KRAS+ CPAM tissue and KRAS- CPAM tissue.In 185 included studies, 143 possible targets were described, of which 20 targets were upregulated and membrane-bound. Six of them were also upregulated in lung AIS tissue (CEACAM5, E-cadherin, EGFR, ERBB2, ITGA2 and MUC1) and as such of possible interest. Validating studies showed that MUC1 is a potential interesting target.This study provides an extensive overview of all known potential targets in CPAM that might identify those patients at risk for malignancy and conducted the first step towards validation, identifying MUC1 as the most promising target.

Postoperative survival of pulmonary invasive mucinous adenocarcinoma versus non-mucinous invasive adenocarcinoma

PURPOSE

In 2015, the World Health Organization renamed mucinous bronchioloalveolar adenocarcinoma as pulmonary invasive mucinous adenocarcinoma (IMA). Due to its low incidence and unclear prognosis with surgical treatment, previous studies have presented opposing survival outcomes. We aimed to investigate the differences in surgical prognosis and prognosis-related risk factors by comparing IMA with non-mucinous invasive adenocarcinoma (NMA).

METHODS

A total of 20,914 patients diagnosed with IMA or NMA from 2000 to 2014 were screened from the Surveillance, Epidemiology, and End Results database. The screened patients were subjected to propensity score matching (PSM) in a 1:4 ratio to explore the survival differences between patients with IMA and NMA and the factors influencing prognosis.

RESULTS

For all patients, IMA was prevalent in the lower lobes of the lungs (p < 0.0001), well-differentiated histologically (p < 0.0001), less likely to have lymph node metastases (94.4% vs. 72.0%, p < 0.0001) and at an earlier pathological stage (p = 0.0001). After PSM, the IMA cohort consisted of 303 patients, and the NMA cohort consisted of 1212 patients. Kaplan‒Meier survival analysis showed no difference in overall survival (OS) between patients in the IMA cohort and those in the NMA cohort (p = 0.7). Cox proportional hazards analysis showed that differences in tumor pathological type did not influence OS between the two cohorts (p = 0.65). Age (HR: 1.98, 95% CI 1.7-2.31, p < 0.0001), gender (HR: 0.64, 95% CI 0.55-0.75, p < 0.0001), and radiation treatment (HR: 2.49, 95% CI 1.84-3.37, p < 0.0001) were independent predictors of patient OS.

CONCLUSION

There was no significant difference in OS between patients with IMA and those with NMA after surgical treatment. Age, sex, and radiation treatment can independently predict OS.

Ramifications of secreted mucin MUC5AC in malignant journey: a holistic view

Heavily glycosylated secreted mucin MUC5AC, by the virtue of its cysteine-rich repeats, can form inter- and intramolecular disulfide linkages resulting in complex polymers, which in turn craft the framework of the polymeric mucus gel on epithelial cell surfaces. MUC5AC is a molecule with versatile functional implications including barrier functions to epithelial cells, host-pathogen interaction, immune cell attraction to sites of premalignant or malignant lesions and tumor progression in a context-dependent manner. Differential expression, glycosylation and localization of MUC5AC have been associated with a plethora of benign and malignant pathologies. In this era of robust technologies, overexpression strategies and genetically engineered mouse models, MUC5AC is emerging as a potential diagnostic, prognostic and therapeutic target for various malignancies. Considering the clinical relevance of MUC5AC, this review holistically encompasses its genomic organization, domain structure, glycosylation patterns, regulation, functional and molecular connotation from benign to malignant pathologies. Furthermore, we have here explored the incipient and significant experimental tools that are being developed to study this structurally complex and evolutionary conserved gel-forming mucin.

Lepidic predominant adenocarcinoma and invasive mucinous adenocarcinoma of the lung exhibit specific mucin expression in relation with oncogenic drivers

OBJECTIVES

To evaluate MUC1, MUC2, MUC5B, MUC5AC, and MUC6 expression in invasive lepidic predominant adenocarcinoma (LPA) and invasive mucinous adenocarcinoma (IMA) of the lung, and the impact of oncogenic drivers.

MATERIALS AND METHODS

MUC1, MUC2, MUC5B, MUC5AC, MUC6, TTF1 and Hnf4α immunohistochemistry was performed on surgical samples from 52 patients with IMA (n=25) or LPA (n=27). We searched for EGFR, KRAS, BRAF, and HER2 mutations and ALK, ROS1, and NRG1 rearrangements.

RESULTS

MUC1, MUC2, MUC5B, MUC5AC, and MUC6 expression was detected in tumor cells in 77%, 2%, 63%, 36%, and 21% of cases, respectively. MUC1 was significantly more overexpressed in LPA. MUC5B, MUC5AC, and MUC6 were typically detected in goblet cells and overexpressed in IMA. Hnf4α-positive IMA (n=11) were TTF1-negative and typically did not expressed MUC1 and expressed MUC5AC and MUC6. Hnf4α-negative IMA (n=14) showed a reverse profile of mucins expression, with MUC1 expression and a lack of MUC5AC and MUC6 expression. EGFR-positive status was significantly associated with LPA, MUC1 expression, and no MUC5B, MUC5AC, or MUC6 expression. KRAS-positive status was significantly associated with IMA and MUC5B and MUC5AC expression.

CONCLUSIONS

LPA and IMA exhibit specific mucin expression profiles, with MUC1 being associated with LPA, while MUC5B, MUC5AC, and MUC6 were associated with IMA. Hnf4α expression and EGFR and KRAS mutations may play a role in mucin expression profiles of these lung adenocarcinoma subtypes.

Prognosis in Resected Invasive Mucinous Adenocarcinomas of the Lung: Related Factors and Comparison with Resected Nonmucinous Adenocarcinomas

INTRODUCTION

In the 2015 World Health Organization classification, invasive mucinous adenocarcinoma (IMA) is categorized as one of various subtypes of lung invasive adenocarcinoma (ADC). However, no comprehensive analysis regarding the clinicoradiologic and prognostic features of IMA has been reported. We aimed to report prognostic factors in IMA and to compare the prognosis of IMAs with that of nonmucinous ADCs.

METHODS

We included 81 patients with a solitary IMA of the lung and analyzed them from the standpoint of clinicoradiologic presentation. Survival rates were assessed and compared with those of 646 resected solitary invasive nonmucinous ADCs.

RESULTS

Patients with IMA showed longer disease-free survival (DFS) than did those with nonmucinous ADCs, whereas overall survival (OS) did not differ significantly (p = 0.023 and p = 0.824, respectively). The DFS of patients with IMA was between that of patients with lepidic predominant (low-grade) and acinar/papillary predominant (intermediate-grade) ADC. In terms of OS, the survival curve of IMA was similar to that of acinar/papillary predominant ADC. Multivariate analysis revealed that tumor size (hazard ratio [HR] = 1.370, 95% confidence interval [CI]: 1.141-1.645, p = 0.001) and maximum standardized uptake value (HR = 1.338, 95% CI: 1.160-1.544, p < 0.001) were independent poor prognostic predictors for DFS. Regarding OS, tumor size (HR = 1.309, 95% CI: 1.092-1.570; p = 0.004) was the only predictor of poor prognosis.

CONCLUSION

Patients with IMA demonstrate a DFS between that of patients with low-grade nonmucinous ADC and that of patients with intermediate-grade nonmucinous ADC and an OS similar to that of patients with intermediate-grade nonmucinous ADC. In IMA, tumor size and maximum standardized uptake value are the factors related to mitigating DFS and tumor size is the only predictor for reduced OS.

Diagnostic and prognostic significances of MUC5B and TTF-1 expressions in resected non-small cell lung cancer

To investigate the relationships between the expression of MUC5B and clinicopathological parameters, the expression of MUC5B was immunohistochemically studied. MUC5B expression was observed in 129 of 198 (65.2%) adenocarcinomas and in 4 of 49 (8.2%) squamous cell carcinomas (P < 0.00001). MUC5B expression was significantly associated with poorer differentiation (P = 0.0303), higher pathological TNM stage (p = 0.0153) and poorer prognosis of adenocarcinoma patients (P = 0.0017). Multivariable analysis with Cox proportional hazards models confirmed that MUC5B expression increased the hazard of death after adjusting for other clinicopathological factors (HR = 2.66; 95%CI, 1.26–5.61). We also immunohistochemically evaluated TTF-1 expression and found that the combination of MUC5B with TTF-1 is a useful marker for adenocarcinomas. The diagnostic accuracies of TTF-1 and MUC5B for adenocarcinoma were 83.8% and 70.4%, respectively. The accuracy increased to 94.3% when the two factors were combined. In survival analysis, the MUC5B(High)/TTF-1(−) group was significantly associated with a poorer outcome compared with the MUC5B(Low)/TTF-1(+) group (p < 0.0001). The present study suggested that the combination of MUC5B and TTF-1 expression is useful for discriminating adenocarcinomas from squamous cell carcinomas, yielding prognostic significance in patients with lung adenocarcinoma.

Relation between thin-section computed tomography and clinical findings of mucinous adenocarcinoma

BACKGROUND

Detailed reports on mucinous adenocarcinoma (formerly "mucinous bronchioloalveolar carcinoma") have not been published. We evaluated the correlation between thin-section computed tomography findings and the clinicopathologic characteristics and prognosis of mucinous adenocarcinoma.

METHODS

From April 1997 to March 2008, 45 resected lung carcinomas were diagnosed as mucinous adenocarcinoma. Five cases of multiple lung cancers or ambiguous mucinous adenocarcinoma were excluded. Tumors were classified as "solitary-type" or "pneumonic-type" tumors according to the thin-section computed tomography findings. We evaluated the clinicopathologic characteristics and the epidermal growth factor receptor and KRAS gene mutation statuses and correlated the thin-section computed tomography findings with patient prognoses.

RESULTS

Thirty patients had solitary-type and 10 had pneumonic-type tumors. The lesions in 23, 14, and 3 patients were classified as pathologic stage I, stage II, and stage III, respectively. Five patients had adenocarcinoma in situ, 9 had minimally invasive adenocarcinoma, and 26 had invasive mucinous adenocarcinoma. Thirteen patients showed recurrences, which were classified as intrapulmonary metastases in all patients. The 5-year overall and relapse-free survival rates were 83.3% and 88.8%, respectively, in patients with solitary-type tumors and 20.0% and 0%, respectively, in patients with pneumonic-type tumors (p < 0.001). The median follow-up time for surviving patients was 81 months. KRAS mutations were detected in 30 patients, but epidermal growth factor receptor mutations were absent in all patients.

CONCLUSIONS

Our results indicated that thin-section computed tomography findings for mucinous adenocarcinoma were useful in predicting prognosis before surgical resection. Further studies are required to improve the treatment strategy for mucinous adenocarcinoma.

Pulmonary adenocarcinoma: implications of the recent advances in molecular biology, treatment and the IASLC/ATS/ERS classification

A decade ago, lung cancer could conveniently be classified into two broad categories-either the small cell lung carcinoma (SCLC), or the non-small cell lung carcinoma (NSCLC), mainly to assist in further treatment related decision making. However, the understanding regarding the eligibility of adenocarcinoma histology for treatments with agents such as pemetrexed and bevacizumab made it a necessity for NSCLC to be classified into more specific sub-groups. Then, the availability of molecular targeted therapy with oral tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib not only further emphasized the need for accurate sub-classification of lung cancer, but also heralded the important role of molecular profiling of lung adenocarcinomas. Given the remarkable advances in molecular biology, oncology and radiology, a need for felt for a revised classification for lung adenocarcinoma, since the existing World Health Organization (WHO) classification of lung cancer, published in the year 2004 was mainly a pathological system of classification. Thus, there was a combined effort by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS) and the European Respiratory Society (ERS) with an effort to inculcate newly established perspectives from clinical, molecular and radiological aspects in evolving a modern classification for lung adenocarcinomas. This review provides a summary of the recent advances in molecular biology and molecular targeted therapy with respect to lung adenocarcinoma. Also, a brief summation of the salient recommendations provided in the IASLC/ATS/ERS classification of lung adenocarcinomas is provided. Lastly, a discussion regarding the future prospects with lung adenocarcinoma is included.

Napsin-A, TTF-1, EGFR, and ALK Status Determination in Lung Primary and Metastatic Mucin-Producing Adenocarcinomas

Pulmonary mucin-producing adenocarcinomas may be indistinguishable on conventional histology from a metastasis, as thyroid transcription factor-1 (TTF-1) expression often is lacking and KRAS mutations are widely present even in extrapulmonary sites. Few data have been reported on the diagnostic role of napsin-A and epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) gene alterations in this challenging differential diagnosis. Seventy-seven surgically resected cases, including 53 primary and 24 metastatic tumors from different sites, were evaluated for napsin-A, TTF-1, and ALK by immunohistochemistry and for EGFR mutations by direct sequencing. Overall, napsin-A expression in primary lung mucin-producing adenocarcinomas was 36% (8% mucinous, 17% colloid, 87.5% solid, and 100% signet ring cell) and TTF-1 expression reached an overall figure of 42% (12.5% mucinous, 33% colloid, 87.5% solid, and 100% signet ring cell). Metastatic mucinous adenocarcinomas did not react with napsin-A or with TTF-1. All primary and metastatic tumors lacked EGFR mutations, while a single case of signet ring cell lung adenocarcinoma showed ALK expression and rearrangement at fluorescent in situ hybridization analysis. Napsin-A has a lower sensitivity compared with TTF-1 in primary mucin-producing adenocarcinomas of the lung. However, both antibodies have an absolute specificity, being always negative in metastatic mucinous adenocarcinomas. EGFR mutations and ALK translocation or expression are exceedingly rare in mucin-producing adenocarcinomas of the lung, resulting unnecessary as diagnostic tool in this setting.

Aberrant Mucin5B expression in lung adenocarcinomas detected by iTRAQ labeling quantitative proteomics and immunohistochemistry

Background

Lung cancer is the number one cause of cancer-related deaths in the United States and worldwide. The complex protein changes and/or signature of protein expression in lung cancer, particularly in non-small cell lung cancer (NSCLC) has not been well defined. Although several studies have investigated the protein profile in lung cancers, the knowledge is far from complete. Among early studies, mucin5B (MUC5B) has been suggested to play an important role in the tumor progression. MUC5B is the major gel-forming mucin in the airway. In this study, we investigated the overall protein profile and MUC5B expression in lung adenocarcinomas, the most common type of NSCLCs.

Methods

Lung adenocarcinoma tissue in formalin-fixed paraffin-embedded (FFPE) blocks was collected and microdissected. Peptides from 8 tumors and 8 tumor-matched normal lung tissue were extracted and labeled with 8-channel iTRAQ reagents. The labeled peptides were identified and quantified by LC-MS/MS using an LTQ Orbitrap Velos mass spectrometer. MUC5B expression identified by iTRAQ labeling was further validated using immunohistochemistry (IHC) on tumor tissue microarray (TMA).

Results

A total of 1288 peptides from 210 proteins were identified and quantified in tumor tissues. Twenty-two proteins showed a greater than 1.5-fold differences between tumor and tumor-matched normal lung tissues. Fifteen proteins, including MUC5B, showed significant changes in tumor tissues. The aberrant expression of MUC5B was further identified in 71.1% of lung adenocarcinomas in the TMA.

Discussions

A subset of tumor-associated proteins was differentially expressed in lung adenocarcinomas. The differential expression of MUC5B in lung adenocarcinomas suggests its role as a potential biomarker in the detection of adenocarcinomas.

Pathobiological implications of MUC4 in non-small-cell lung cancer

INTRODUCTION

Altered expression of MUC4 plays an oncogenic role in various cancers, including pancreatic, ovarian, and breast. This study evaluates the expression and role of MUC4 in non-small-cell lung cancer (NSCLC).

METHODS

We used a paired system of MUC4-expressing (H292) and MUC4-nonexpressing (A549) NSCLC cell lines to analyze MUC4-dependent changes in growth rate, migration, and invasion using these sublines. We also evaluated the alterations of several tumor suppressor, proliferation, and metastasis markers with altered MUC4 expression. Furthermore, the association of MUC4 expression (by immunohistochemistry) in lung cancer samples with patient survival was evaluated.

RESULTS

MUC4-expressing lung cancer cells demonstrated a less proliferative and metastatic phenotype. Up-regulation of p53 in MUC4-expressing lung cancer cells led to the accumulation of cells at the G2/M phase of cell cycle progression. MUC4 expression attenuated Akt activation and decreased the expression of Cyclins D1 and E, but increased the expression of p21 and p27. MUC4 expression abrogated cancer cell migration and invasion by altering N- & E-cadherin expression and FAK phosphorylation. A decrease in MUC4 expression was observed with increasing tumor stage (mean composite score: stage I, 2.4; stage II, 1.8; stage III, 1.4; and metastatic, 1.2; p = 0.0093). Maximal MUC4 expression was associated with a better overall survival (p = 0.042).

CONCLUSION

MUC4 plays a tumor-suppressor role in NSCLC by altering p53 expression in NSCLC. Decrease in MUC4 expression in advanced tumor stages also seems to confirm the novel protective function of MUC4 in NSCLC.

Diagnosis of lung adenocarcinoma in resected specimens: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

A new lung adenocarcinoma classification has been published by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. This new classification is needed to provide uniform terminology and diagnostic criteria, most especially for bronchioloalveolar carcinoma. It was developed by an international core panel of experts representing all 3 societies with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons.This summary focuses on the aspects of this classification that address resection specimens. The terms bronchioloalveolar carcinoma and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced, such as adenocarcinoma in situ and minimally invasive adenocarcinoma for small solitary adenocarcinomas with either pure lepidic growth (adenocarcinoma in situ) and predominant lepidic growth with invasion of 5 mm or less (minimally invasive adenocarcinoma), to define the condition of patients who will have 100% or near 100% disease-specific survival, respectively, if they undergo complete lesion resection. Adenocarcinoma in situ and minimally invasive adenocarcinoma are usually nonmucinous, but rarely may be mucinous. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous bronchioloalveolar carcinoma), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid, fetal, and enteric adenocarcinoma.It is possible that this classification may impact the next revision of the TNM staging classification, with adjustment of the size T factor according to only the invasive component pathologically in adenocarcinomas with lepidic areas.

Nkx2-1 represses a latent gastric differentiation program in lung adenocarcinoma

Tissue-specific differentiation programs become dysregulated during cancer evolution. The transcription factor Nkx2-1 is a master regulator of pulmonary differentiation that is downregulated in poorly differentiated lung adenocarcinoma. Here we use conditional murine genetics to determine how the identity of lung epithelial cells changes upon loss of their master cell-fate regulator. Nkx2-1 deletion in normal and neoplastic lungs causes not only loss of pulmonary identity but also conversion to a gastric lineage. Nkx2-1 is likely to maintain pulmonary identity by recruiting transcription factors Foxa1 and Foxa2 to lung-specific loci, thus preventing them from binding gastrointestinal targets. Nkx2-1-negative murine lung tumors mimic mucinous human lung adenocarcinomas, which express gastric markers. Loss of the gastrointestinal transcription factor Hnf4α leads to derepression of the embryonal proto-oncogene Hmga2 in Nkx2-1-negative tumors. These observations suggest that loss of both active and latent differentiation programs is required for tumors to reach a primitive, poorly differentiated state.

MUC4 as a diagnostic marker in cancer

BACKGROUND

Mucins are high molecular mass glycoproteins whose role in diagnosis, prognosis and therapy is being increasingly recognized owing to their altered expression in a variety of carcinomas. MUC4, a membrane-bound mucin encoded by a gene located on chromosome locus 3q29, is aberrantly expressed in several cancers including those of the bile duct, breast, colon, esophagus, ovary, lung, prostate, stomach and pancreas.

OBJECTIVE

This review considers the potential use of the MUC4 expression pattern in the diagnosis and prognosis of various cancers.

RESULTS/CONCLUSION

MUC4 expression is a specific marker of epithelial tumors and its expression correlates positively with the degree of differentiation in several cancers. Importantly, MUC4 has emerged as a specific marker of dysplasia, being expressed in the earliest dysplastic lesions preceding several malignancies, including lethal pancreatic cancer. The presence of MUC4-specific antibodies in the serum and of the transcript in peripheral blood mononuclear cells of cancer patients raises the possibility of it emerging as a new diagnostic biomarker for bedside application in high-risk individuals and those with established cancer.

New pathologic classification of lung cancer: relevance for clinical practice and clinical trials

We summarize significant changes in pathologic classification of lung cancer resulting from the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) lung adenocarcinoma classification. The classification was developed by an international core panel of experts representing IASLC, ATS, and ERS with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. Because 70% of patients with lung cancer present with advanced stages, a new approach to small biopsies and cytology with specific terminology and criteria focused on the need for distinguishing squamous cell carcinoma from adenocarcinoma and on molecular testing for EGFR mutations and ALK rearrangement. Tumors previously classified as non-small-cell carcinoma, not otherwise specified, because of the lack of clear squamous or adenocarcinoma morphology should be classified further by using a limited immunohistochemical workup to preserve tissue for molecular testing. The terms "bronchioloalveolar carcinoma" and "mixed subtype adenocarcinoma" have been discontinued. For resected adenocarcinomas, new concepts of adenocarcinoma in situ and minimally invasive adenocarcinoma define patients who, if they undergo complete resection, will have 100% disease-free survival. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic, acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype with poor prognosis. Former mucinous bronchioloalveolar carcinomas are now called "invasive mucinous adenocarcinoma." Because the lung cancer field is now rapidly evolving with new advances occurring on a frequent basis, particularly in the molecular arena, this classification provides a much needed standard for pathologic diagnosis not only for patient care but also for clinical trials and TNM classification.

Value of thyroid transcription factor-1 immunostaining in tumor diagnosis: a review and update

Thyroid transcription factor-1 (TTF-1) is a tissue-specific transcription factor that plays a critical role in the normal development of embryonic epithelial cells of the thyroid and lung. Because TTF-1 expression is highly restricted to epithelial tumors arising in these organs, it is, at present, one of the immunohistochemical markers most commonly used to assist in the differential diagnosis of carcinomas of the lung and thyroid. Recent studies, however, have reported that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought as it can be found to be expressed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Even though this unexpected TTF-1 positivity has been reported more frequently with the recently available SPT24 anti-TTF-1 monoclonal antibody, it has also been shown to occur with the commonly used 8G7G3/1 clone, albeit in a lower percentage of cases. Despite these findings, TTF-1 remains a very useful immunohistochemical marker in diagnostic pathology.

The complex intratumoral heterogeneity of colon cancer highlighted by laser microdissection

AIMS

To evaluate the utility of laser microdissection in the comparison of phenotypes and genetic alterations between colon cancer and corresponding liver metastasis in the context of intratumoral heterogeneity.

METHODS

Immunohistochemistry was performed on a series of 11 patients surgically treated for colon adenocarcinoma with liver metastases, using antibodies directed against six mucins. Immunohistochemistry was completed by laser microdissection of tumor zones with particular phenotype, luminal zone and invasion front of colon tumors. Microdissected samples were compared on the basis of microsatellite instability and alterations of CTNNB1, KRAS, and TP53.

RESULTS

Our study demonstrated varying mucin expression within tumors, suggesting the existence of phenotypic intratumoral heterogeneity. A common immunohistochemical profile was observed in individual tumors between tumoral subpopulations and corresponding metastases. Nevertheless, the phenotypic characteristics were distinct from one patient to another. Laser microdissection underlined that phenotypic heterogeneity could rely on genotypic heterogeneity, and that some genetic alterations were common to microdissected samples from primary colon tumors and liver metastases.

CONCLUSION

We illustrated intratumoral heterogeneity of colon cancer using laser microdissection, in combination with immunohistochemical and genotypic tools. This intratumoral heterogeneity could represent a major issue in the search of prognostic biomarkers.

MUC5AC, cytokeratin 20 and HER2 expression and K-RAS mutations within mucinogenic growth in congenital pulmonary airway malformations

AIMS

  To analyse the expression of several mucins (MUC1, MUC2, MUC3, MUC5AC and MUC6), epidermal growth factor receptor (EGFR), v-erb-b2 erythroblastic leukaemia viral oncogene homologue 2 (HER2), thyroid transcription factor-1 (TTF-1), caudal type homeobox 2 (CDX2) and cytokeratin 20 (CK20), and the presence of mutations of EGFR, KRAS and HER2 in congenital pulmonary airway malformations (CPAM).

METHODS AND RESULTS

  Forty-one cases of CPAM and six pulmonary sequestrations were included. TTF-1 expression was observed in all cases but was not seen in mucinogenic growths in CPAM. CDX2 expression was completely negative. MUC1 expression was noted in 12 (29%) CPAM and in 33% sequestrations. MUC5AC was noted in only five cases (26%) by immunohistochemistry and was found in the mucinogenic proliferations of type 1 CPAM. No immunolabelling was noted for the other mucins. EGFR was expressed variably in almost all cases, while HER2 and CK20 was seen exclusively in the mucinogenic proliferations. All mucinous growths were characterized by KRAS mutations. No EGFR and HER2 gene alterations were identified.

CONCLUSIONS

  KRAS mutations and MUC5AC, CK20 and HER2 expression was seen in all mucinogenic proliferations, supporting the neoplastic nature of these cytologically bland growths. These findings emphasize the importance of complete surgical resection of such lesions.

The predominant expression of hepatocyte nuclear factor 4α (HNF4α) in thyroid transcription factor-1 (TTF-1)-negative pulmonary adenocarcinoma

AIMS

To investigate TTF-1-negative pulmonary adenocarcinoma, focusing upon mucin production and the expression of hepatocyte nuclear factor-4α (HNF4α).

MATERIALS AND METHODS

Two hundred and sixty-two cases of pulmonary adenocarcinoma were examined histologically and immunohistochemically; TTF-1 was expressed in 222 cases (84.7%), and 40 cases (15.3%) were negative. Among TTF-1-negative cases there were 31 mucinous-type tumours, and HNF4α, MUC5AC and MUC2 were expressed in 34 cases (85%), 29 cases (72.5%) and four cases (10%), respectively. In contrast, their expression was rare in TTF-1-positive tumours. A statistically inverse correlation was confirmed between the expression of TTF-1 and that of HNF4α and MUC5AC.

CONCLUSION

Most TTF-1-negative pulmonary adenocarcinomas are mucinous lesions with the predominant expression of HNF4α and MUC5AC.

Surgical resection for patients with mucinous bronchioloalveolar carcinoma

BACKGROUND

The clinical features of mucinous bronchioloalveolar carcinoma (BAC) have remained unclear due to the low incidence of this disease. This study investigated the clinicopathological features and the surgical outcome in patients with mucinous BAC.

METHODS

We clinicopathologically evaluated 782 patients who underwent resection for nonsmall cell carcinoma between 1999 and 2008, of whom, 13 (1.6%) demonstrated to have mucinous BAC.

RESULTS

The patients with mucinous BAC included six men and seven women. The mean age was 69.1 years (range: 55-78 years). Eight patients (61.5%) had a smoking habit. No patients had any subjective symptoms. The tumour diameter ranged from 1.2 cm to 10 cm. The surgical procedures included 11 lobectomies, and two partial resections of affected lobes. The pathological stage was IA in eight patients, IB in two, IIA in two, and IIIA in one. None of the patients had lymph node metastases or lymphovascular invasion. The overall postoperative 5-year survival rate was 52.5%. The 5-year survival rate according to tumour diameter was 100% in patients with tumours ≤ 3 cm, and 25.1% in patients with tumours > 3 cm. Two patients died due to pulmonary metastases, and one died from carcinomatous pleuritis and pulmonary metastases.

CONCLUSION

Patients with small mucinous BAC (≤ 3 cm) in diameter showed excellent prognosis after surgical resection. However, mucinous BAC > 3 cm in diameter tended to recur with pulmonary metastasis.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

The mouse Muc5b mucin gene is transcriptionally regulated by thyroid transcription factor-1 (TTF-1) and GATA-6 transcription factors

MUC5B is one of the major mucin genes expressed in the respiratory tract. Previous studies in our laboratory have demonstrated that MUC5B is expressed in human lung adenocarcinomas and during lung morphogenesis. Moreover, in human lung adenocarcinoma tissues, a converse correlation between MUC5B and thyroid transcription factor-1 (TTF-1) expression, a lung-specific transcription factor, has been established. However, the molecular mechanisms that govern the regulation of MUC5B expression in the lung are largely unknown. In order to better understand the biological role of MUC5B in lung pathophysiology, we report the characterization of the promoter region of the mouse Muc5b mucin gene. The promoter is flanked by a TATA box (TACATAA) identical to that in the human gene. Human and murine promoters share 67.5% similarity over the first 170 nucleotides. By RT-PCR, co-transfection studies and gel-shift assays, we show that Muc5b promoter activity is completely inhibited by TTF-1, whereas factors of the GATA family (GATA-4/GATA-5/GATA-6) are activators. Together, these results demonstrate, for the first time, that Muc5b is a target gene of transcription factors (TTF-1, GATA-6) involved in lung differentiation programs during development and carcinogenesis, and identify TTF-1 as a strong repressor of Muc5b. The characterization of the structural and functional features of the Muc5b mucin gene will provide us with a strong base to develop studies in murine models aimed at the identification of its biological role in lung pathophysiology.

A transcriptional network signature characterizes lung cancer subtypes

BACKGROUND

Transcriptional networks play a central role in cancer development. The authors described a systems biology approach to cancer classification based on the reverse engineering of the transcriptional network surrounding the 2 most common types of lung cancer: adenocarcinoma (AC) and squamous cell carcinoma (SCC).

METHODS

A transcriptional network classifier was inferred from the molecular profiles of 111 human lung carcinomas. The authors tested its classification accuracy in 7 independent cohorts, for a total of 422 subjects of Caucasian, African, and Asian descent.

RESULTS

The model for distinguishing AC from SCC was a 25-gene network signature. Its performance on the 7 independent cohorts achieved 95.2% classification accuracy. Even more surprisingly, 95% of this accuracy was explained by the interplay of 3 genes (KRT6A, KRT6B, KRT6C) on a narrow cytoband of chromosome 12. The role of this chromosomal region in distinguishing AC and SCC was further confirmed by the analysis of another group of 28 independent subjects assayed by DNA copy number changes. The copy number variations of bands 12q12, 12q13, and 12q12-13 discriminated these samples with 84% accuracy.

CONCLUSIONS

These results suggest the existence of a robust signature localized in a relatively small area of the genome, and show the clinical potential of reverse engineering transcriptional networks from molecular profiles.

Membrane-bound mucins: the mechanistic basis for alterations in the growth and survival of cancer cells

Mucins (MUC) are high molecular weight O-linked glycoproteins whose primary functions are to hydrate, protect, and lubricate the epithelial luminal surfaces of the ducts within the human body. The MUC family is comprised of large secreted gel forming and transmembrane (TM) mucins. MUC1, MUC4, and MUC16 are the well-characterized TM mucins and have been shown to be aberrantly overexpressed in various malignancies including cystic fibrosis, asthma, and cancer. Recent studies have uncovered the unique roles of these mucins in the pathogenesis of cancer. These mucins possess specific domains that can make complex associations with various signaling pathways, impacting cell survival through alterations of cell growth, proliferation, death, and autophagy. The cytoplasmic domain of MUC1 serves as a scaffold for interaction with various signaling proteins. On the other hand, MUC4 mediates its effect by stabilizing and enhancing the activity of growth factor receptor ErbB2. MUC16, previously known as CA125, is a well-known serum marker for the diagnosis of ovarian cancer and has a key role in stimulation and dissemination of ovarian cancer cells by interacting with mesothelin and galectin. Therefore, herein we discuss the function and divergent mechanisms of MUC1, MUC4, and MUC16 in carcinogenesis in the context of alteration in cell growth and survival.

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.

Transcriptional network classifiers

Background

Gene interactions play a central role in transcriptional networks. Many studies have performed genome-wide expression analysis to reconstruct regulatory networks to investigate disease processes. Since biological processes are outcomes of regulatory gene interactions, this paper develops a system biology approach to infer function-dependent transcriptional networks modulating phenotypic traits, which serve as a classifier to identify tissue states. Due to gene interactions taken into account in the analysis, we can achieve higher classification accuracy than existing methods.

Results

Our system biology approach is carried out by the Bayesian networks framework. The algorithm consists of two steps: gene filtering by Bayes factor followed by collinearity elimination via network learning. We validate our approach with two clinical data. In the study of lung cancer subtypes discrimination, we obtain a 25-gene classifier from 111 training samples, and the test on 422 independent samples achieves 95% classification accuracy. In the study of thoracic aortic aneurysm (TAA) diagnosis, 61 samples determine a 34-gene classifier, whose diagnosis accuracy on 33 independent samples achieves 82%. The performance comparisons with three other popular methods, PCA/LDA, PAM, and Weighted Voting, confirm that our approach yields superior classification accuracy and a more compact signature.

Conclusions

The system biology approach presented in this paper is able to infer function-dependent transcriptional networks, which in turn can classify biological samples with high accuracy. The validation of our classifier using clinical data demonstrates the promising value of our proposed approach for disease diagnosis.

Regulation of airway mucin gene expression

Mucins are important components that exert a variety of functions in cell-cell interaction, epidermal growth factor receptor signaling, and airways protection. In the conducting airways of the lungs, mucins are the major contributor to the viscoelastic property of mucous secretion, which is the major barrier to trapping inhaled microbial organism, particulates, and oxidative pollutants. The homeostasis of mucin production is an important feature in conducting airways for the maintenance of mucociliary function. Aberrant mucin secretion and accumulation in airway lumen are clinical hallmarks associated with various lung diseases, such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, emphysema, and lung cancer. Among 20 known mucin genes identified, 11 of them have been verified at either the mRNA and/or protein level in airways. The regulation of mucin genes is complicated, as are the mediators and signaling pathways. This review summarizes the current view on the mediators, the signaling pathways, and the transcriptional units that are involved in the regulation of airway mucin gene expression. In addition, we also point out essential features of epigenetic mechanisms for the regulation of these genes.

Mucinous Cells in Type 1 Pulmonary Congenital Cystic Adenomatoid Malformation as Mucinous Bronchioloalveolar Carcinoma Precursors

Type 1 congenital cystic adenomatoid malformation (CCAM), the most frequent malformation of the lung, is the only type to present intracystic mucinous cell clusters, which may form beyond the cysts extracystic mucinous proliferation resembling mucinous bronchioloalveolar carcinomas (BACs). As mucinous BACs are increasingly described in the literature in young patients with CCAM, we hypothesized that type 1 CCAM mucinous cells could represent BAC precursors. We reviewed 7 cases of type 1 CCAM including 6 with intracystic mucinous cell clusters, 3 with extracystic mucinous proliferations, and 4 with mucinous BAC or mixed adenocarcinoma with predominant BAC. K-ras mutations at codon 12 were detected in 3/3 intracystic mucinous cell clusters, in 2/3 extracystic mucinous proliferations, and in 3/4 BAC. Loss of heterozygosity (LOH) at p16(INK4) locus, with microsatellite alterations in 3 cases, was observed in 2/3 intracystic mucinous cell clusters, in 2/3 extracystic mucinous proliferations, and in all BAC. Two extracystic mucinous proliferations showed LOH at FHIT and Rb loci, respectively. P16(INK4) expression was lost in 2 intracystic mucinous cell clusters, 1 extracystic mucinous proliferation, and 1 BAC. Neither epidermal growth factor receptor mutation on exons 18, 19, and 21 nor P53 accumulation was observed. All lesions expressed MUC5AC, but were negative for MUC2, CDX2, and TTF-1. In conclusion, type 1 CCAM mucinous cells share the same differentiation profile with corresponding mucinous BAC, consistent with a common bronchial origin. Moreover, the high frequency of K-ras mutation and LOH and/or microsatellite alterations at p16(INK4) locus presented by these mucinous cells justifies their consideration as BAC precursors.

Signet-Ring Cell Adenocarcinoma of Sinonasal Tract: An Immunohistochemical Study of the Mucins Profile

Context.—Adenocarcinomas of the sinonasal tract are classified into 4 categories: salivary-type, intestinal-type, nonintestinal-type, and metastatic. Signet-ring cell carcinoma is the rarest form of intestinal-type adenocarcinoma. Only isolated cases have been reported in the literature.

Objective.—To evaluate clinical attributes, morphology, and immunohistochemistry in signet-ring cell carcinoma of the sinonasal tract.

Design.—Seventy-three cases of primary sinonasal adenocarcinomas were retrieved from the files. Only 5 signet-ring cell adenocarcinomas (tumors composed of more than 90% signet-ring cells) were identified. In all cases, clinical data and histologic slides were available and were reviewed. Consecutive tissue sections were immunostained with monoclonal antibodies against MUC2, MUC5AC, MUC5B, MUC6, p53 protein, and MIB-1.

Results.—Four of our 5 patients were woodworkers. They were treated by surgical excision and radiotherapy. Patient follow-up ranged from 11 to 84 months. Three patients presented an unfavorable evolution and died of metastatic spread. Microscopically, the tumors produced abundant mucin deposits, which accumulated in large extracellular pools. Tumor cells were predominantly signet-ring cells floating in the pools of mucin. The mucins profile was MUC2+, MUC5AC+, MUC5B+, and MUC6−. Eighty percent of cells were immunostained by p53 protein antibody and 60% cells with MIB-1 antibody.

Conclusions.—The mucin profile is similar to the profile described in digestive tract adenocarcinoma. It is not useful to differentiate between metastatic adenocarcinoma and primary intestinal-type sinonasal adenocarcinoma. Clinical data and immunochemistry with p53 protein and MIB-1 confirm that sinonasal signet-ring cell carcinoma is a high-grade and aggressive tumor.

The role of MUC1 and MUC3 in the biology and prognosis of colorectal cancer

Background

MUC1 and MUC3 are from a large family of glycoproteins with an aberrant expression profile in various malignancies. Much interest has been focused on the role of these proteins in the development and progression of colorectal cancer; however, no previous studies have included the highly confounding variable of vascular invasion in their survival analysis. Using high throughput tissue microarray technology we assessed the prognostic value of MUC1 and MUC3 expression in the largest cohort of colorectal cancer patients to date. We propose that tumours lacking expression of MUC1 and MUC3 will be more likely to metastasise, due to previously observed loss of cell-cell adhesion, and this will therefore lead to more aggressive cancers with poorer prognosis.

Methods

A tissue micro-array was prepared from tumour samples of 462 consecutive patients undergoing resection of a primary colorectal cancer. A comprehensive prospectively recorded data base with mean follow up of 75 months was collected and included common clinicopathological variables and disease specific survival. Immunohistochemical analysis of MUC1 and MUC3 expression was performed using antibodies NCL-MUC1 and 1143/B7 respectively, results were correlated with the variables within the database.

Results

Positive expression of MUC1 and MUC3 was seen in 32% and 74% of tumours respectively. On univariate analysis no correlation was seen with either MUC1 or MUC3 and any of the clinicopathological variables including tumour grade and stage, vascular invasion and tumour type. Kaplan-Meier analysis demonstrated a significant reduction in disease specific survival with MUC1 positive tumours (p = 0.038), this was not seen with MUC3 (p = 0.552). On multivariate analysis, using Cox proportional hazards model, MUC1 expression was shown to be an independent marker of prognosis (HR 1.339, 95%CI 1.002–1.790, p = 0.048).

Conclusion

MUC1 expression in colorectal cancer is an independent marker of poor prognosis, even when vascular invasion is included in the analysis. These results support previous studies suggesting a role for MUC1 in colorectal cancer development possibly through its effects on cell adhesion.

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

MUC1 is a large trans-membrane highly glycosylated mucin which is expressed at the apical pole of normal cells in glandular epithelia. MUC1 is implicated in many physiological mechanisms such as adhesion, development and differentiation. Also, MUC1 is frequently deregulated and over-expressed with a membrane circumferential and/or cytoplasmic expression. The intracellular tail of MUC1 is phosphorylated and can interact with many signalling proteins and transcriptional factors. Indeed, MUC1 can interact with B-catenin competitively for E-cadherin, thus destabilizing intercellular junctions and favouring metastatic dissemination. In carcinomas, the overexpression and membrane delocalization of MUC1 is associated with a worse prognosis and a shorter survival in breast, colon, kidney, prostate or gastro-intestinal cancers. MUC1 appears to be a novel therapeutic target for immunotherapy or anti-tumour vaccines.

Mechanisms of mucin production by rhinovirus infection in cultured human airway epithelial cells

Mucus hypersecretion relates to exacerbations of bronchial asthma and chronic obstructive pulmonary disease (COPD) caused by rhinovirus (RV) infection. We examined the mechanisms of RV infection-induced mucin production in human tracheal surface epithelial cells and submucosal gland cells. RV14 up-regulated the mRNA expression of MUC2, MUC3, MUC5AC, MUC5B and MUC6, and increased MUC5AC and total mucin concentration in supernatants and lysates of the surface cells. An inhibitor of the nuclear factor kappaB caffeic acid phenylethyl ester, inhibitors of selective p44/42 mitogen-activated protein kinase-kinase PD98059 and U0126, and a selective Src inhibitor PP1 attenuated MUC5AC mRNA expression, and secretion and production of MUC5AC and total mucin glycoprotein in the surface cells. In the gland cells, RV14 also increased mRNA expression of MUC2, MUC5AC, MUC5B and MUC7, and the inhibitors attenuated the secretion of total mucin glycoprotein. Src-related p44/42 mitogen-activated protein kinase pathway may be associated with RV-induced mucin hypersecretion in human airways.

MUC4 expression correlates with poor prognosis in small-sized lung adenocarcinoma

The mortality of lung cancer remains high, despite improved diagnostic techniques that allow small lung tumors to be detected. In this study, we evaluated the prognostic significance of the tracheal mucin MUC4 by immunohistochemical investigation of the expression profiles of MUC4, ErbB2, p27 and MUC1 in lung adenocarcinoma specimens (non-bronchiolo-alveolar type, < or =3cm) from 185 patients. MUC4 is a membrane mucin, similarly to MUC1, and in addition MUC4 functions as an intra-membrane ligand for receptor tyrosine kinase ErbB2 and is associated with regulation of p27. However, MUC4 expression was found to be unrelated to expression of MUC1, ErbB2 and p27 in small-sized lung adenocarcinomas. The disease-free interval (DFI) and survival rate of 25 patients with high MUC4 expression (> or =25% of neoplastic cells stained) were significantly lower than those of 160 patients with low MUC4 expression (<25% of neoplastic cells stained) (P<0.05), whereas ErbB2 and p27 expression showed no significant correlation with DFI and survival. Univariate analysis showed that high MUC4 and p27 expression correlated with blood vessel invasion (P=0.0004), and MUC4 expression was frequently detected in regions of stromal invasion. In addition, the survival rate of stage IA patients with high MUC4 expression was significantly lower than that of stage IA patients with low MUC4 expression (P<0.05). In conclusion, high MUC4 expression in small-sized lung adenocarcinomas correlates with a short DFI and a poor survival rate. Therefore, MUC4 expression might be a new independent factor for prediction of outcome and indication of poor prognosis in lung adenocarcinoma.

MUC1, MUC2, MUC4, MUC5AC and MUC6 expression in the progression of prostate cancer

Molecular changes are vital for the development of prognostic markers and therapeutic modalities of prostate cancer (CaP). There is growing interest in mucins as treatment targets in human malignancies, including CaP. The role of their expression in the progression of CaP is however unclear. We examined the expressions MUC1, MUC2, MUC4, MUC5AC and MUC6 in CaP tissues using tissue microarrays (TMAs) to look for tumor-associated antigens (TAAs) for targeted therapy. In this study, 120 paraffin-embedded specimens were selected from patients who underwent radical retro-pubic prostatectomy (RRP) or trans-urethral-resection of the prostate (TURP) for primary, untreated CaP and 10 matched lymph node metastases. A series of MUC monoclonal antibodies (mAbs) was used on TMAs by standard immunohistochemistry. Our results indicate that the over-expression of MUC1 was detected in 58% of primary CaP tissues and 90% of lymph node metastases but not in normal prostate or benign tissues, while the expression of MUC2, MUC4, MUC5AC and MUC6 was found to be negative in both normal and cancer tissues. Of the MUC1 positive tumors 86% were Gleason grade 7 or higher. Over-expression of MUC1 was found in late stage CaP while MUC2, 4, 5AC and 6 were negative in CaP. MUC1 is a TAA that is highly related to tumor progression in CaP patients. This antigen is ideal for targeted therapy to control micrometastases and hormone refractory disease but additional studies are necessary to assess its usefulness in patient biopsies and CaP bone metastases before clinical trial.

Gastric foveolar metaplasia with dysplastic changes in Brunner gland hyperplasia: possible precursor lesions for Brunner gland adenocarcinoma

Cases of adenocarcinomas developed in Brunner gland hyperplasia (BGH) have been sporadically reported. Herein, we report the morphologic spectrum of hyperplastic changes culminating into dysplasia and carcinoma in 722 cases of BGH listed in our files. Fifteen of these cases showed dysplastic changes, with 8 graded as low-grade dysplasia, 5 as high-grade dysplasia, 11 as atypical hyperplasia, and 2 as invasive carcinoma, although each frequently coexisted in the same tumor. In two carcinomas, one had high-grade dysplasia in the mucosa, and another had only atypical hyperplasia. Interestingly, hyperplastic glands around dysplastic foci were associated with gastric foveolar metaplasia and papillary configuration in 13 cases, 11 of which showed a gradual increase in nuclear atypism in the transition from metaplastic to dysplastic glands. All of the metaplastic gastric glands showed diffuse and strong immunopositivity for gastric foveolar mucin (MUC5AC). Immunohistochemical profiles also supported the concept of a continuous spectrum in carcinogenesis from gastric foveolar hyperplasia through atypical hyperplasia or dysplasia and eventually to frank adenocarcinoma. The results of our study suggest, therefore, that dysplastic and/or carcinomatous change does occur in BGH, that they form the continuous morphologic spectrum, and that papillary foveolar metaplasia may be a precursor lesion in the process of carcinogenesis with a background of BGH.

Comparison of the immunophenotypes of signet-ring cell carcinoma, solid adenocarcinoma with mucin production, and mucinous bronchioloalveolar carcinoma of the lung characterized by the presence of cytoplasmic mucin

The latest World Health Organization (WHO) classification divides adenocarcinoma mainly into adenocarcinoma mixed subtypes, acinar adenocarcinoma, papillary adenocarcinoma, bronchioloalveolar carcinoma, and solid adenocarcinoma with mucin production, and it mentions several variants, including fetal adenocarcinoma, mucinous ("colloid") adenocarcinoma, mucinous cystadenocarcinoma, signet-ring adenocarcinoma, and clear cell adenocarcinoma. In general, the mucin-producing adenocarcinoma of the lung comprises signet-ring cell carcinoma (SRCC), solid adenocarcinoma with mucin production (SA), and mucinous bronchioloalveolar carcinoma (m-BAC), mucinous ("colloid") adenocarcinomas and/or mucinous cystadenocarcinoma, and mucoepidermoid carcinoma. As SRCC, SA, and m-BAC exhibit distinct clinical features, it is important to identify differences in their immunohistochemical characteristics to better understand their histogenesis. In this study we analysed SRCC, SA, m-BAC, normal lung, and foregut-related secretory tissue for immunohistochemical differences using tissue microarrays. SRCC and SA showed high expression of MUC1 (97.4% and 100%, respectively), cytokeratin (CK) 7 (both 100%), and thyroid transcription factor-1 (TTF-1) (81.1% and 100%, respectively). They also showed low expression of MUC5AC (25.5% and 21.1%, respectively) and MUC6 (18.3% and 10.5%, respectively), whereas m-BAC showed high expression of MUC5AC (97.5%), MUC6 (75.0%), and CK7 (94.7%), but low expression of MUC1 (57.5%), and TTF-1 (27.5%). Hierarchical clustering showed that the immunophenotypes of SRCC and SA belong to the same category as alveolar lining cells, whereas m-BAC clustered onto another branch with gastric foveolar cells and bronchial goblet cells. These immunohistochemical findings support the results of our previous clinicopathological analysis of SRCC of the lung showing that SRCC occurs anatomically in the peripheral portion of the lung rather than in the bronchial gland-bearing portion.

Immunohistochemical analysis of MUC5B apomucin expression in breast cancer and non-malignant breast tissues

A deregulation of several MUC genes (MUC1, MUC2, MUC3, MUC5AC, and MUC6) was previously demonstrated in breast carcinomas. Considering that recently we found the "non-mammary" MUC5B mRNA in primary breast tumors (Berois et al. 2003), we undertook the present study to evaluate the expression profile of MUC5B protein product in breast tissues, using LUM5B-2 antisera raised against sequences within the non-glycosylated regions of this apomucin. Expression of MUC5B by breast cancer cells was confirmed by immunocytochemistry, in situ hybridization, and Western blot on MCF-7 cancer cells. Using an immunohistochemical procedure, MUC5B apomucin was detected in 34/42 (81%) primary breast tumors, in 13/14 (92.8%) samples of non-malignant breast diseases, in 8/19 (42.1%) samples of normal-appearing breast epithelia adjacent to cancer, and in 0/5 normal control breast samples. The staining pattern of MUC5B was very different when comparing breast cancer cells (cytoplasmic) and non-malignant breast cells (predominantly apical and in the secretory material). We analyzed MUC5B mRNA expression using RT-PCR in bone marrow aspirates from 22/42 patients with breast cancer to compare with MUC5B protein expression in the primary tumors. Good correlation was observed because the six MUC5B-positive bone marrow samples also displayed MUC5B expression in the tumor. Our results show, for the first time at the protein level, that MUC5B apomucin is upregulated in breast cancer. Its characterization could provide new insights about the glycobiology of breast cancer cells.

Unique expression of MUC3, MUC5AC and cytokeratins in salivary gland carcinomas

The differential diagnosis of salivary gland carcinoma is often difficult because of the confusing histopathological features of the different types of salivary gland carcinomas. The expression of MUC3, MUC5AC, MUC6, cytokeratin (CK)7 and CK20 was studied in 20 mucoepidermoid carcinomas (MEC), 20 adenoid cystic carcinomas (AdCC), and 11 acinic cell carcinomas (ACC). All the cases (51/51, 100%) were positive for CK7, but they were not positive for CK20. All the cases (100%) of the MEC were positive for MUC5AC, while all MEC (100%) were negative for MUC3. Only two cases (10%) were positive for MUC6. All cases (100%) of AdCC were negative for MUC3, MUC5AC and MUC6. Eight cases (73%) of ACC were positive for MUC3, but all the cases (100%) were negative for MUC5AC and MUC6. It is concluded that the positive expression of MUC5AC is very unique to MEC, and that the positive expression of MUC3 is very unique to ACC. These findings will be very useful for the differential diagnosis of the salivary gland carcinomas.

Adenocarcinoma of the thymus: mucinous subtype

Primary thymic adenocarcinoma, mucinous subtype, is extremely rare with only one case reported to date. We describe herein a case of thymic mucinous adenocarcinoma. A 59-year-old man was identified to have an anterior mediastinal tumor and was diagnosed as mucinous adenocarcinoma. Clinical and radiographic examinations disclosed no evidence of tumor elsewhere. The patient received radiotherapy, but the general condition deteriorated and died 11 months after tumor detection. Thoracic autopsy revealed an anterior mediastinal tumor measuring greater than 10 cm, uncapsulated, and white. The tumor had clear margins and was clearly isolated from the lung. Histologically, the tumor demonstrated papillary, acinar, and cribriform structure and produced abundant extracellular mucin. Immunohistochemically, most tumor cells were positive for cytokeratin 7, were partially positive for CD5, and were negative for TTF-1, Sp-A, CDX-2, MUC2, napsin A, and cytokeratin 20. Collectively, the diagnosis of the tumor was primary mucinous adenocarcinoma of the thymus. We propose that the mucinous subtype should be recognized as one of the histopathological entities of thymic adenocarcinoma.

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.

Primary Mucinous (So-called Colloid) Carcinomas of the Lung

Herein we describe the clinicopathologic and immunohistochemical features of 13 primary mucinous (colloid) carcinomas (MCs) of the lung, an uncommon and controversial tumor. The patients, 7 males and 6 females, ranged in age from 50 to 79 years (mean, 64.5 years). All the tumors presented as a peripheral solitary nodule with gelatinous cut-surface and well circumscribed but lacking a complete fibrous wall. The size ranged from 1 to 5.5 cm. Microscopically, they consisted of neoplastic elements floating in large mucin pools and focally lining the alveolar spaces. Eleven cases were predominantly composed of tall, columnar goblet cells (goblet cell-type MC), while 2 consisted of signet-ring tumor cells (signet-ring cell-type MC). Five tumors were incidentally discovered by chest radiographs, while the others were symptomatic. All patients underwent complete surgical resection (six lobectomies and seven wedge resections). Postoperative chemotherapy was performed in 3 cases. Overall, the median follow-up was 26 months (mean 33 months; range 9-95 months). All patients with goblet cell-type MC were alive and well, while the 2 patients with signet-ring cell-type MC died of disease. Immunohistochemically, all the 11 goblet cell-type MCs were strongly stained with CDX-2 and MUC2, 8 reacted with TTF-1, 6 with cytokeratin 20 (CK20), 9 with cytokeratin 7 (CK7), and 2 with MUC-5AC. Conversely, the two signet-ring cell-type MCs were stained with TTF-1, CK7, and MUC5AC but were negative for CDX-2, MUC2, and CK20. Surfactant apoprotein-A (SP-A) was positive in four goblet cell-type and one signet-ring cell-type MC. When compared with 10 mucinous bronchioloalveolar carcinomas (m-BAC), the latter reacted with CK7, CK20, MUC5AC, TTF-1, SP-A, CDX-2, and MUC2 in 100%, 90%, 100%, 30%, 10%, 0%, and 0% of the cases, respectively. In summary, MC of the lung represents an entity with two distinct clinicopathologic and immunophenotypic variants: 1) the goblet cell-type, presenting a more indolent clinical behavior and frequently co-expressing markers of intestinal and pulmonary differentiation; and 2) the more aggressive signet-ring cell-type, which retains only markers of pulmonary origin. On morphologic and immunohistochemical grounds, MCs are easily distinguishable from m-BAC. Since goblet cell-type MC strongly stains with CDX2, MUC2, and CK20, differential diagnosis with metastatic colorectal carcinoma is very challenging and requires appropriate clinical correlation.

Generation and characterization of anti-MUC4 monoclonal antibodies reactive with normal and cancer cells in humans

We have previously cloned the full-length cDNA (approximately 28 Kb) and established the complete genomic organization (25 exons/introns over 100 kb) of the human MUC4 mucin. This large molecule is predicted to protrude over 2 microm above the cell surface, in which MUC4alpha is an extracellular mucin-type glycoprotein subunit and MUC4beta is the transmembrane subunit. Over two thirds of the encoded protein sequence consists of 16-amino-acid tandem repeats (TR), which are flanked by unique sequences. In this study we generated and characterized monoclonal antibodies (MAbs) directed against the TR region of MUC4. Mice were immunized with a KLH-conjugated MUC4 TR peptide, STGDTTPLPVTDTSSV. Several clones were purified by three rounds of limited dilutions and stable clones presenting a sustained antibody production were selected for subsequent characterization. Antibodies were tested for their reactivity and specificity to recognize the MUC4 peptide and further screened by enzyme-linked immunosorbent assay (ELISA) and Western blotting analyses. One of the MAbs (8G7) was strongly reactive against the MUC4 peptide and with native MUC4 from human tissues or pancreatic cancer cells in Western blotting, immunohistochemistry, and confocal analysis. Anti-MUC4 MAb may represent a powerful tool for the study of MUC4 function under normal and pathological conditions and for diagnosis of solid tumors including those in the breast, pancreas, lungs, and ovaries.

Diagnostic value of MUC4 immunostaining in distinguishing epithelial mesothelioma and lung adenocarcinoma

The distinction between pleural malignant mesothelioma and pleural infiltration by adenocarcinomas has complex therapeutic and medicolegal implications. Although the panel of adenocarcinoma-associated antibodies and one or two mesothelioma markers is useful in this purpose, most of these antibodies are not totally specific. We determined the diagnostic value of MUC4 immunostaining in this issue. MUC4 gene expression was also studied by in situ hybridization and RT-PCR. MUC4 is a membrane-bound mucin that has been suggested to be implicated in malignant progression in humans and rats. The MUC4 gene is expressed in various normal epithelial tissues of endodermic origin and carcinomas. In the respiratory tract, MUC4 transcripts have been detected in normal respiratory epithelium and lung carcinomas. MUC4 protein was expressed in 32 of 35 (91.4%) lung adenocarcinomas on paraffin-embedded tissue. None of the 41 malignant mesotheliomas nor the 32 cases of benign mesothelial cells expressed MUC4 at the protein and mRNA levels. We conclude that MUC4 is a very specific (100%) and sensitive (91.4%) marker of lung adenocarcinomas on paraffin-embedded tissue that could be useful in diagnostic practice in the distinction between malignant mesothelioma and adenocarcinoma.

The mouse secreted gel-forming mucin gene cluster

Using genomic cosmid and BAC clones and genome shotgun supercontigs available in GenBank, we determined the complete gene structure of the four mouse secreted gel-forming mucin genes Muc2, Muc5ac, Muc5b and Muc6 and the organization of the genomic locus harboring these genes. The mouse secreted gel-forming mucin gene is 215 kb on distal chromosome 7 to 69.0 cM from the centromere and organized as: Muc6-Muc2-Muc5ac-Muc5b with Muc2, Muc5ac and Muc5b arranged in the same orientation and Muc6 in opposite. Mouse mucin genes have highly similar genomic organization to each other and to their respective human homologues indicating that they have been well conserved through evolution. Deduced peptides showed striking sequence similarities in their N- and C-terminal regions whereas the threonine/serine/proline-rich central region is specific for each other and for species. Expression studies also showed that they have expression patterns similar to human mucin genes with Muc2 expressed in small and large intestines, Muc5ac and Muc6 in stomach, and Muc5b in laryngo-tracheal tract. These data constitute an important initial step for investigation of mucin gene regulation and mucin function through the use of animal models.

Quantitative RT-PCR assay for MUC3 and VEGF mRNA in renal clear cell carcinoma: relationship with nuclear grade and prognosis

OBJECTIVES

To investigate, by real-time quantitative reverse transcriptase-polymerase chain reaction, the expression of MUC3 and vascular endothelial growth factor (VEGF) to correlate them with histologic parameters and with prognosis. Human mucins are large O-glycoproteins expressed in epithelial tissues. Deregulation of mucin genes has been demonstrated in several epithelial neoplasms. In the kidney, MUC3 is expressed in normal convoluted tubules and in renal clear cell carcinoma.

METHODS

Twenty-six renal clear cell carcinoma specimens were studied. For all tumors, samples of normal and tumor kidney were frozen. After RNA extraction, using ultracentrifugation through a cesium chloride cushion, VEGF and MUC3 mRNA were analyzed by real-time quantitative reverse transcriptase-polymerase chain reaction. The pathologic parameters included Fuhrman nuclear grade and TNM stage. All follow-up data were available.

RESULTS

The median level of MUC3 and VEGF expression was greater in tumor areas compared with normal areas (P < 0.002 and P < 0.001, respectively). The MUC3 tumor/normal tissue expression ratio was greater in nuclear grade 3 tumor than in low grades (grade 1-2; P < 0.005). No statistically significant relationship was found with the prognosis for MUC3 and VEGF in our study.

CONCLUSIONS

The results of this study demonstrate that MUC3 and VEGF are overexpressed in renal clear cell carcinoma, and the MUC3 expression ratio is greater in nuclear grade 3 than in grades 1 and 2 (low grades) tumor. These findings suggest the implication of MUC3 in renal carcinogenesis.