MUC1 expression in thymic epithelial tumors: MUC1 may be useful marker as differential diagnosis between type B3 thymoma and thymic carcinoma

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

Learning the Autoimmune Pathogenesis Through the Study of Aire

One of the difficulties in studying the pathogenesis of autoimmune diseases is that the disease is multifactorial involving sex, age, MHC, environment, and some genetic factors. Because deficiency of Aire, a transcriptional regulator, is an autoimmune disease caused by a single gene abnormality, Aire is an ideal research target for approaching the enigma of autoimmunity, e.g., the mechanisms underlying Aire deficiency can be studied using genetically modified animals. Nevertheless, the exact mechanisms of the breakdown of self-tolerance due to Aire's dysfunction have not yet been fully clarified. This is due, at least in part, to the lack of information on the exact target genes controlled by Aire. State-of-the-art research infrastructures such as single-cell analysis are now in place to elucidate the essential function of Aire. The knowledge gained through the study of Aire-mediated tolerance should help our understanding of the pathogenesis of autoimmune disease in general.

Thymic Carcinoma: Unraveling Neuroendocrine Differentiation and Epithelial Cell Identity Loss

BACKGROUND

The histogenesis of thymic epithelial tumors (TETs) has been a subject of debate. Recent technological advancements have revealed that thymic carcinomas often exhibit a phenotype akin to tuft cells, which is a subset of medullary TECs. Here, we further explored the gene expression signatures of thymic carcinomas in relation to tuft cells and their kinships-ionocytes and neuroendocrine cells (neuroendocrine group).

METHODS

We analyzed a single-cell RNA sequencing dataset from the normal human thymus. Concurrently, we examined publicly available datasets on the mRNA expression and methylation status of TECs and lung cancers. Real-time quantitative PCR was also conducted with our tissue samples.

RESULTS

Thymic carcinomas displayed a neuroendocrine phenotype biased toward tuft cells and ionocytes. When exploring the possible regulators of this phenotype, we discovered that HDAC9 and NFATC1 were characteristically expressed in the neuroendocrine group in adult TECs and thymic carcinomas. Additionally, the pan-thymic epithelium markers, exemplified by PAX9 and SIX1, were significantly suppressed in thymic carcinomas.

CONCLUSIONS

Thymic carcinomas might be characterized by unique neuroendocrine differentiation and loss of identity as thymic epithelial cells. Future studies investigating the role of HDAC9 and NFATC1 in thymic epithelium are warranted to explore their potential as therapeutic targets in TETs.

Dataset for reporting of thymic epithelial tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

Thymic epithelial tumours (TET), including thymomas and thymic carcinomas and thymic neuroendocrine neoplasms, are malignant neoplasms that can be associated with morbidity and mortality. Recently, an updated version of the World Health Organization (WHO) Classification of Thoracic Tumours 5th Edition, 2021 has been released, which included various changes to the classification of these neoplasms. In addition, in 2017 the Union for International Cancer Control (UICC) / American Joint Committee on Cancer (AJCC) published the 8th Edition Staging Manual which, for the first time, includes a TNM staging that is applicable to thymomas, thymic carcinomas, and thymic neuroendocrine neoplasms.

METHODS AND RESULTS

To standardize reporting of resected TET and thymic neuroendocrine neoplasms the accrediting bodies updated their reporting protocols. The International Collaboration on Cancer Reporting (ICCR), which represents a collaboration between various National Associations of Pathology, updated its 2017 histopathology reporting guide on TET and thymic neuroendocrine neoplasms accordingly. This report will highlight important changes in the reporting of TET and thymic neuroendocrine neoplasms based on the 2021 WHO, emphasize the 2017 TNM staging, and also comment on the rigour and various uncertainties for the pathologist when trying to follow that staging.

CONCLUSION

The ICCR dataset provides a comprehensive, standardized template for reporting of resected TET and thymic neuroendocrine neoplasms.

AIRE illuminates the feature of medullary thymic epithelial cells in thymic carcinoma

Despite the clear distinction between cortical (cTECs) and medullary thymic epithelial cells (mTECs) in physiology, the cell of origin of thymic carcinomas (TCs) and other thymic epithelial tumors remained enigmatic. We addressed this issue by focusing on AIRE, an mTEC-specific transcriptional regulator that is required for immunological self-tolerance. We found that a large proportion of TCs expressed AIRE with typical nuclear dot morphology by immunohistochemistry. AIRE expression in TCs was supported by the RNA-seq data in the TCGA-THYM database. Furthermore, our bioinformatics approach to the recent single-cell RNA-seq data on human thymi has revealed that TCs hold molecular characteristics of multiple mTEC subpopulations. In contrast, TCs lacked the gene signatures for cTECs. We propose that TCs are tumors derived from mTECs.

Atypical thymomas with squamoid and spindle cell features: clinicopathologic, immunohistochemical and molecular genetic study of 120 cases with long-term follow-up

Thymomas are rare tumors characterized by a broad range of morphologic appearances that can sometimes give rise to difficulties for classification. We have studied a series of 120 thymoma patients in whom the tumors were characterized by sheets of atypical epithelial cells with squamoid and/or spindle cell features. They occurred in 63 men and 57 women and presented as a discrete mass in the anterior mediastinum measuring 2-23 cm (mean: 8.2 cm). Patients' ages ranged from 14 to 86 years (mean: 57.8) and most had symptoms referable to a mass lesion. 20 patients had myasthenia gravis or other autoimmune disorder. 76 cases were characterized by a predominant population of round to polygonal tumor cells while 32 cases were characterized by atypical oval or spindle cells. 12 cases showed mixed features and 16 cases showed the development of thymic carcinoma arising from thymoma. All cases were positive for p40/p63 and cytokeratin AE1/AE3. 23 cases were positive for CD5 (25%), and 13 for CD117 (14%). MIB1 showed a significant increase in proliferative activity (mean = 11.6%). Next generation sequencing in 47 cases did not disclose any variants amenable to current targeted therapies. Clinical follow up ranging from 2 to 29 years showed a progressive increase in aggressive behavior and fatality rate with advancing stage. Overall survival was 87% at 5 years, 67% at 10 years, and 23% at 20 years. Completeness of resection and staging were the most significant parameters for survival. The more aggressive tumors followed a protracted clinical course with multiple recurrences and metastases over a long period of time (mean = 19.8 years from time of initial relapse to death). Atypical thymomas are a distinct category of thymic epithelial neoplasm characterized by a slowly progressive clinical course with increased potential for metastases, transformation to a higher-grade malignancy, and fatal outcome in some cases.

CD70 in Thymic Squamous Cell Carcinoma: Potential Diagnostic Markers and Immunotherapeutic Targets

CD70 – a ligand protein of CD27 on lymphocytes – is expressed in a large spectrum of malignancies. It is an attractive target for antibody-based therapy and several clinical trials are currently being conducted. However, there is no evidence regarding the expression of CD70 and its relationship with expression of programmed death ligand-1 (PD-L1) and CD27+ tumor-infiltrating lymphocytes (TIL) in formalin-fixed paraffin-embedded (FFPE) tissues of thymic tumors. FFPE tissues of thymic squamous cell carcinoma (TSCC) (operative specimens, n = 31; biopsy specimens, n = 11), thymoma (n = 60), thymic carcinoid (n = 3), and lung squamous cell carcinoma (LSCC) (n = 30) were analyzed immunohistochemically. Immunoreactivity for CD70 was semi-quantitatively scored according to the proportion of positive tumor cells. Moreover, the densities of CD27-positive intratumoral TIL (iTIL) and stromal TIL of TSCC were assessed and survival was compared. Most TSCC cases (87%; 27/31) were CD70-positive. In contrast, all thymoma and thymic carcinoid cases were CD70-negative. In LSCC cases, CD70-positivity was significantly lower than TSCC cases (20%; 6/30). Biopsy and resected specimens obtained from the same patients demonstrated a consistent staining pattern (6/6 patients). The proportion of CD70-positive TSCC was comparable with those of CD5 (87%) and CD117 (90%). Correlation between CD70 and PD-L1 expression score was observed. There was no significant difference in survival between the CD70-high and CD70-low expression groups. Meanwhile, patients with CD27-positive iTIL-high tumors exhibited better survival than those with iTIL-low tumors. This tendency was weaker in the CD70-high subset. CD70 immunohistochemistry is useful in diagnosing TSCC. CD70 may prevent anti-tumor immunity via CD27. Immunotherapy targeting the CD70–CD27 axis may be a promising option for the treatment of TSCC.

Relationship of possible biomarkers with malignancy of thymic tumors: a meta-analysis

Background

Role of biomarkers for promotion of tumor proliferation (BPTPs) and for promotion of apoptosis (BPAs) in thymic malignant tumors is still unclear. The purpose of this study was to evaluate the relationship between BPTPs and/or BPAs and malignancy of thymic malignant tumors.

Methods

Studies on thymic malignant tumors and biomarkers were searched in PubMed, ISI Web of Knowledge, and Embase databases, and all statistical analyses were conducted using Review Manager.

Results

Twelve articles related to biomarkers and thymic malignant tumors were selected and analyzed. A relationship between BPAs and Masaoka stage was demonstrated for four markers, namely Bax, p73, Casp-9 and Bcl-2, included 138 stage I/II patients and 74 stage III/IV patients, and BPAs were significantly correlated with high Masaoka staging (P = 0.03). We further found a relationship between BPAs and degree of malignancy for four markers, namely Bax, p73, Casp-9 and Bcl-2, included 176 thymoma patients and 36 thymic carcinoma patients, and BPAs were significantly correlated with thymic carcinoma (P = 0.010). In addition, a relationship between BPTP and Masaoka staging was demonstrated for seven markers, namely Podoplanin, Glut-1, Muc-1, Egfr, Igf1r, c-Jun, and n-Ras, included 373 patients with stage I/II and 212 patients with stage III/IV, and BPTPs were significantly correlated with high Masaoka staging (P < 0.001). We also found a relationship between BPTPs and degree of malignancy for ten markers, namely Mesothelin, c-Kit (CD117), Egfr, Lat-1, Muc-1,Ema, Glut-1, Igf1r, c-Jun, and n-Ras, included 748 thymoma patients and 280 thymic carcinoma patients, and BPTPs were significantly correlated with thymic carcinoma (P < 0.001).

Conclusion

These findings show that high levels of BPTPs or BPAs are more closely related to thymic carcinoma and Masaoka stage III/IV, suggesting that BPTPs and BPAs may play an important role in the occurrence and development of thymic malignant tumors.

Diagnostic Roles of Immunohistochemistry in Thymic Tumors: Differentiation between Thymic Carcinoma and Thymoma

Background: The present study aims to evaluate the diagnostic roles of various immunohistochemical (IHC) markers in thymic tumors, including thymic carcinoma (TC) and thymoma (TM). Methods: Eligible studies were obtained by searching the PubMed databases and screening the searched articles. Thirty-eight articles were used in the present meta-analysis and included 636 TCs and 1861 TMs. Besides, for IHC markers with statistical significance, a diagnostic test accuracy review was performed. Results: The comparison of various IHC expressions between TC and TM was performed for 32 IHC markers. Among these IHC markers, there were significant differences between TC and TM for beta-5t, B-cell lymphoma 2 (Bcl-2), calretinin, CD1a, CD5, carcinoembryonic antigen (CEA), cytokeratin19 (CK19), CD117, glucose transporter 1 (Glut-1), insulin-like growth factor 1 receptor (IGF-1R), mesothelin, MOC31, mucin1 (MUC1), p21, and terminal deoxynucleotidyl transferase (TdT). Markers with higher expressions in TCs were Bcl-2, calretinin, CD5, CEA, CD117, Glut-1, IGF-1R, mesothelin, MOC31, MUC1, and p21. Among these markers, there were no significant differences between TC and TM type B3 in immunohistochemistries for Bcl-2 and CK19. On the other hand, β-catenin and CD205 showed a considerable difference in IHC expressions between TC and TM type B3, but not between TC and overall TM. In diagnostic test accuracy review, MUC1 and beta-5t were the most useful markers for TC and TM, respectively. Conclusions: Taken together, our results showed that the expression rates for various IHC markers significantly differed between TC and TM. The IHC panel can be useful for differentiation from limited biopsied specimens in daily practice.

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

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

Clinical and prognostic significance of signal transducer and activator of transcription 3 and mucin 1 in patients with non-small cell lung cancer following surgery

Signal transducer and activator of transcription 3 (STAT3) and mucin 1 (MUC1) are associated with development, progression and a poor prognosis in several types of cancer. The present study investigated the levels of STAT3 and MUC1 in patients with non-small cell lung cancer (NSCLC) following surgery. In total, 98 patients with NSCLC were enrolled into the study. STAT3, phosphorylated (p)-STAT3 and MUC1 expression in NSCLC specimens obtained from patients were investigated using immunohistochemical analysis. Enumeration results were analyzed using the χ² test or Fisher's exact probability test. Spearman's rank correlation was used to analyze correlations between STAT3, p-STAT3 and MUC1 expression. Univariate analysis was conducted using the Kaplan-Meier estimator curve method and Cox regression multivariate analysis was performed in order to determine prognostic factors. Results demonstrated that STAT3 and p-STAT3 expression was identified in 82 and 51 patients, respectively. Furthermore, the expression of MUC1 was identified in 61/98 cases (62.2%) and STAT3 expression was significantly associated with pathological tumor-node-metastasis stage (pTNM; P<0.01). p-STAT3 expression was associated with pathological type (P<0.01), pathological lymph nodes (pN; P<0.01) and pTNM (P<0.05). MUC1 expression was associated with pathological type (P<0.05), pathological tumor pT (P<0.05), pN (P<0.01) and pTNM (P<0.01). STAT3 expression was positively associated with p-STAT3 expression (P<0.05) and p-STAT3 expression was positively associated with MUC1 expression (P<0.01). Overall, the results identified that the 3-year survival rate was 56.1% and was significantly associated with the degree of differentiation (P<0.05), pT (P<0.01), pN (P<0.01), pTNM stage (P<0.01), p-STAT3 expression (P<0.01) and MUC1 expression (P<0.05). Results obtained from the Cox multivariate regression analysis demonstrated that pN and p-STAT3 expression were independent factors associated with the 3-year survival rate.

MUC1 downregulation inhibits non-small cell lung cancer progression in human cell lines

Mucin 1 (MUC1) is a transmembrane glycoprotein that is aberrantly unregulated in numerous types of cancer, including non-small cell lung cancer (NSCLC), and serves a key role as an oncogene in the tumorigenesis of various human adenocarcinomas. Studies have indicated that MUC1 is involved in cell proliferation, invasion and migration. However, the role of MUC1 in NSCLC progression remains poorly understood. The aim of the present study was to investigate the role of MUC1 in stable MUC1-low-expression NSCLC cell lines that were generated by transfection with MUC1-siRNA. Cell Counting Kit-8 assay was preformed to determine the proliferation ability of NSCLC cells, while cell apoptosis was detected using flow cytometry. In addition, the mRNA and protein expression levels of MUC1 were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Western blot analysis was also used for detection of other associated proteins. The results demonstrated that, compared with the control group, the cell proliferation ability was significantly declined in the MUC1 inhibition group, and the cell apoptosis rate was markedly increased. Inhibition of MUC1 gene in NCI-H1650 cells suppressed cell proliferation and induced cell apoptosis. In addition, the protein expression levels of vascular endothelial growth factor (VEGF) and VEGF-C were notably decreased by MUC1 inhibition, indicating the anti-angiogenic effect of MUC1 downregulation. Furthermore, inhibition of MUC1 gene with MUC1-siRNA significantly suppressed the phosphorylation of protein kinase B and extracellular signal-regulated kinase. In conclusion, the findings indicated that silencing of MUC1 gene may inhibit the development of NSCLC cells.

Dataset for reporting of thymic epithelial tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

The International Collaboration on Cancer Reporting (ICCR) is a not-for-profit organization formed by the Royal Colleges of Pathologists of Australasia and the United Kingdom, the College of American Pathologists, the Canadian Association of Pathologists-Association Canadienne des Pathologists in association with the Canadian Partnership Against Cancer, and the European Society of Pathology. Its goal is to produce standardized, internationally agreed, evidence-based datasets for use throughout the world.

METHODS AND RESULTS

This article describes the development of a cancer dataset by the multidisciplinary ICCR expert panel for the reporting of thymic epithelial tumours. The dataset includes 'required' (mandatory) and 'recommended' (non-mandatory) elements, which are validated by a review of current evidence and supported by explanatory text. Seven required elements and 12 recommended elements were agreed by the international dataset authoring committee to represent the essential information for the reporting of thymic epithelial tumours.

CONCLUSIONS

The use of an internationally agreed, structured pathology dataset for reporting thymic tumours provides all of the necessary information for optimal patient management, facilitates consistent and accurate data collection, and provides valuable data for research and international benchmarking. The dataset also provides a valuable resource for those countries and institutions that are not in a position to develop their own datasets.

Diagnostic roles of MUC1 and GLUT1 in differentiating thymic carcinoma from type B3 thymoma

MUC1 is a transmembrane mucin that has been related to tumor progression and outcome in various malignancies. GLUT1 is a member of the mammalian facilitative glucose transporter (GLUT) family of passive carriers that functions as an energy-independent system for transporting glucose. Both of them are useful markers for the diagnosis, progression, and prognosis of various tumors, especially those that are cancerous. However, the clinical significance of MUC1 and GLUT1 in thymic epithelial tumors remains uncertain due to a lack of quality specimen and studies at sufficient scale, both owing, in part, to the rarity of the tumors. The aim of this article is to study the expression patterns of MUC1 and GLUT1 in thymic carcinoma and type B3 thymoma, and to evaluate their diagnostic value for these two types of tumors via immunohistochemistry. Forty-three patients were included in the study, including twenty-two with thymic carcinoma and twenty-one with type B3 thymoma. Tumor tissue sections were immunohistochemically stained for MUC1 and GLUT1; meanwhile, some tumors were also stained with CKpan, TDT, CD5, and CD117. MUC1 was expressed in a total of 17 cases, with a positive rate of 77.27% (17/22) in thymic carcinoma and 9.52% (2/21) in type B3 thymoma, revealing a significant difference (p<0.0001). A significant difference (p<0.0001) was also shown for GLUT1, where the positive rates for thymic carcinoma and type B3 thymoma were 100% (22/22) and 42.86% (9/21), respectively. The expression of MUC1 was significantly correlated with GLUT1 (p<0.0001). Furthermore, GLUT1 staining sensitivity and specificity for thymic carcinoma were 100% (22/22) and 70.97% (22/31), respectively, while MUC1 staining sensitivity and specificity were 77.27% (17/22) and 89.47% (17/19), respectively. In conclusion, our study shows that MUC1 and GLUT1 staining may play a useful role in differentiating thymic carcinoma from type B3 thymoma, with high sensitivity and specificity.

Clinicopathological analysis of 241 thymic epithelial tumors-experience in the Shanghai Chest Hospital from 1997-2004

BACKGROUND

To assess the correlation of WHO histological classification of thymomas and thymic carcinomas (TCs) with prognosis in recently treated patient cohort compared to a historical one from a single institution.

METHODS

Retrospective review of clinical charts and histological sections of 241 patients treated during 1997-2004. Univariate and multivariate analysis of associations between risk factors including gender, age, tumor size, myasthenia gravis, WHO histological subtype, Masaoka stage, resection status, (neo-)adjuvant therapies, and survival.

RESULTS

The 5-year overall survival (OS) of A, AB, B1, B2, B3 thymomas and TCs patients was 100%, 100%, 94%, 80%, 94% and 45%. Five-year progression-free survival (PFS) was 100%, 96%, 78%, 80%, 78% and 39%, respectively. The 5-year OS of patients with Masaoka stage I, II, III and IV thymomas and TCs was 96%, 89%, 59% and 50%. (Neo-)adjuvant therapies were administered more often than in the historical cohort. Tumor-related death mainly occurred in patients with stage III, IV and B2, B3 thymomas and TCs. By univariate analysis, gender, tumor size, myasthenia gravis (MG) status, histotype, Masaoka stage, resection status and treatment were associated with OS. By multivariate analysis, histological subtype, Masaoka stage, and (neo-)adjuvant therapy were revealed as independent prognostic indicators.

CONCLUSIONS

WHO histological subtype, Masaoka stage and (neo-)adjuvant treatment have remained independent determinants of OS in patients with thymomas and TCs. Compared with the historical cohort during 1969-1996, prognosis of patients with B2, B3 thymomas has improved, which may be partly due to the increased use of adjuvant therapies. Prognosis of patients with TCs remained unsatisfactory, suggesting that neoadjuvant treatment should be tested to improve survival.

Immunohistochemistry in the diagnosis of thymic epithelial neoplasms

The diagnosis of thymic epithelial neoplasms is normally rendered after careful evaluation of their histologic features. In some cases, however, the morphological heterogeneity or overlap with neoplasms of other organ systems can lead to diagnostic uncertainty. On the basis of this, the use of immunohistochemical stains as a diagnostic adjunct has become a popular tool. Although undoubtedly, immunohistochemistry has its role in the diagnosis of difficult cases, to date there are no specific markers that would distinguish thymic epithelial neoplasms from other tumors and interpretation of immunohistochemical results should only ever be made in conjunction with accurate morphologic analysis and careful clinical evaluation. This article will review the current knowledge of the immunohistochemical phenotype of thymic epithelial neoplasms with particular emphasis on its use for diagnostic purposes and the latest advances in this field.

MUC1 and metastatic cancer: expression, function and therapeutic targeting

MUC1 is a transmembrane mucin that is often overexpressed in metastatic cancers and often used as a diagnostic marker for metastatic progression. The extracellular domain of MUC1 can serve as a ligand for stromal and endothelial cell adhesion receptors, and the cytoplasmic domain engages in several interactions that can result in increased migration and invasion, as well as survival. In this review, we address the role of MUC1 in metastatic progression by assessing clinical studies reporting MUC1 levels at various disease stages, reviewing mouse models utilized to study the role of MUC1 in metastatic progression, discuss mechanisms of MUC1 upregulation, and detail MUC1 protein interactions and signaling events. We review interactions between MUC1 and the extracellular environment, with proteins colocalized in the plasma membrane and/or cytoplasmic proteins, and summarize the role of MUC1 in the nucleus as a transcriptional cofactor. Finally, we review recent publications describing current therapies targeting MUC1 in patients with advanced disease and the stage of these therapies in preclinical development or clinical trials.

MUC1 drives c-Met-dependent migration and scattering

The transmembrane mucin MUC1 is overexpressed in most ductal carcinomas, and its overexpression is frequently associated with metastatic progression. MUC1 can drive tumor initiation and progression via interactions with many oncogenic partners, including β-catenin, the EGF receptor (EGFR) and Src. The decoy peptide protein transduction domain MUC1 inhibitory peptide (PMIP) has been shown to inhibit the tumor promoting activities of MUC1 in breast and lung cancer, including cell growth and invasion, and its usage suppresses metastatic progression in mouse models of breast cancer. To further characterize the reduced metastasis observed upon PMIP treatment, we conducted motility assays and observed that PMIP inhibits cell motility of breast cancer cells. To determine the mechanism by which PMIP inhibits motility, we evaluated changes in global gene transcription upon PMIP treatment, and identified a number of genes with altered expression in response to PMIP. Among these genes is the metastatic mediator, c-Met, a transmembrane tyrosine kinase that can promote cell scattering, migration, and invasion. To further investigate the role of c-Met in MUC1-dependent metastatic events, we evaluated the effects of MUC1 expression and EGFR activation on breast cancer cell scattering, branching, and migration. We found that MUC1 strongly promoted all of these events and this effect was further amplified by EGF treatment. Importantly, the effect of MUC1 and EGF on these phenotypes was dependent upon c-Met activity. Overall, these results indicate that PMIP can block the expression of a key metastatic mediator, further advancing its potential use as a clinical therapeutic.

Overexpression of MUC1 enhances proangiogenic activity of non-small-cell lung cancer cells through activation of Akt and extracellular signal-regulated kinase pathways

BACKGROUND

Angiogenesis is an important process required for tumor progression. Mucin 1 (MUC1) is a transmembrane glycoprotein that is aberrantly upregulated in many types of cancer, including non-small-cell lung cancer (NSCLC). However, the biological significance of MUC1 overexpression in lung cancer angiogenesis is not completely understood.

METHODS

We showed that enforced expression of MUC1 in two NSCLC cell lines, A549 and NCI-H460, which have a low level of endogenous MUC1, promoted their ability to induce vascular endothelial growth factor (VEGF)-dependent endothelial cell migration and tube formation.

RESULTS

There was a significant increase in VEGF expression in MUC1-overexpressing NSCLC cells. Moreover, MUC1 overexpression resulted in a marked elevation in phosphorylated Akt and extracellular signal-regulated kinase (ERK)1/2, indicative of activation of both signaling pathways. Most importantly, inhibition of Akt or ERK signaling using specific chemical inhibitors restrained the proangiogenic activity of MUC1-overexpressing NSCLC cells.

CONCLUSIONS

Taken together, our present data demonstrate that the aberrant upregulation of MUC1 favors tumor angiogenesis in NSCLC, likely through the activation of both Akt and ERK pathways and elevation of VEGF production. MUC1 may thus be a potential antiangiogenic target in NSCLC.