Homeobox transcriptional factor engrailed homeobox 1 is expressed specifically in normal and neoplastic sweat gland cells

TGFβ-induced EN1 promotes tumor budding of adenoid cystic carcinoma in patient-derived organoid model

Adenoid cystic carcinoma (ACC) and basal cell adenoma (BCA) share many histological characteristics and often need a differential diagnosis in clinical pathology. Recently, we found homeobox protein engrailed-1 (EN1) was a potential diagnostic marker for ACC in an organoids library of salivary gland tumors (SGTs). Here we aim to confirm EN1 as a differential diagnostic marker for ACC, and further investigate the regulatory mechanism and biological function of EN1 in tumor progression. The transcriptional analysis, quantitative polymerase chain reaction, Western blot and immunohistochemistry staining were performed and revealed that EN1 was specifically and highly expressed in ACC, and accurately differentiated ACC from BCA. Furthermore, TGFβ signaling pathway was found associated with ACC, and the regulation of EN1 through TGFβ was detected in the human ACC cell lines and patient-derived organoids (PDOs). TGFβ-induced EN1 was important in promoting tumor budding in the PDOs model. Interestingly, a high level of EN1 and TGFβ1 in the budding tips was observed in ACC clinical samples, and the expression of EN1 and TGFβ1 in ACC was significantly associated with the clinical stage. In summary, our study verified EN1 is a good diagnostic marker to differentiate ACC from BCA. TGFβ-induced EN1 facilitates the tumor budding of ACC, which might be an important mechanism related to the malignant phenotype of ACC.

EN1 promotes lung metastasis of salivary adenoid cystic carcinoma by regulating the PI3K-AKT pathway and epithelial-mesenchymal transition

BACKGROUND

Engrailed homeobox 1 (EN1) is a candidate oncogene that is epigenetically modified in salivary adenoid cystic carcinoma (SACC). We investigated the expression of EN1 in SACC tissues and cells, EN1 promoter methylation, and the role of EN1 in tumour progression in SACC.

METHODS

Thirty-five SACC samples were screened for key transcription factors that affect tumour progression. In vitro and in vivo assays were performed to determine the viability, tumorigenicity, and metastatic ability of SACC cells with modulated EN1 expression. Quantitative methylation-specific polymerase chain reaction analysis was performed on SACC samples.

RESULTS

EN1 was identified as a transcription factor that was highly overexpressed in SACC tissues, regardless of clinical stage and histology subtype, and its level of expression correlated with distant metastasis. EN1 promoted cell invasion and migration through epithelial-mesenchymal transition in vitro and enhanced SACC metastasis to the lung in vivo. RNA-seq combined with in vitro assays indicated that EN1 might play an oncogenic role in SACC through the PI3K-AKT pathway. EN1 mRNA levels were negatively correlated with promoter hypermethylation, and inhibition of DNA methylation by 5-aza-dC increased EN1 expression.

CONCLUSIONS

The transcription factor EN1 is overexpressed in SACC under methylation regulation and plays a pivotal role in SACC progression through the PI3K-AKT pathway. These results suggest that EN1 may be a diagnostic biomarker and a potential therapeutic target for SACC.

Differential antigen expression between human apocrine sweat glands and eccrine sweat glands

Bromhidrosis has a great negative impact on personal occupation and social psychology. It is not yet clear whether bromhidrosis is caused by apocrine sweat glands or the co-action of apocrine sweat glands and eccrine sweat glands. To distinguish between apocrine sweat glands and eccrine sweat glands, specific antigen markers for apocrine sweat glands and eccrine sweat glands must be found first. In the study, we detected the expression of K7, K18, K19, Na+-K+-2Cl- cotransporter 1 (NKCC1), carbonic anhydrase II (CAII), Forkhead transcription factor a1 (Foxa1), homeobox transcription factor engrailed homeobox1 (En1), gross cystic disease fluid protein-15 (GCDFP-15), mucin-1 (MUC-1), cluster of differentiation 15 (CD15) and apolipoprotein (APOD) in eccrine sweat glands and apocrine sweat glands by immunofluorescence staining. The results showed that K7, K18, K19, Foxa1, GCDFP-15 and MUC-1 were expressed in both apocrine and eccrine sweat glands, CD15 and APOD were only expressed in apocrine sweat glands, and CAII, NKCC1 and En1 were only expressed in eccrine sweat glands. We conclude that CD15 and APOD can serve as specific markers for apocrine sweat glands, while CAII, NKCC1 and En1 can serve as specific markers for eccrine sweat glands to differentiate the two sweat glands.

Non-invasive human skin transcriptome analysis using mRNA in skin surface lipids

Non-invasive acquisition of mRNA data from the skin can be extremely useful for understanding skin physiology and diseases. Inspired by the holocrine process, in which the sebaceous glands secrete cell contents into the sebum, we focused on the possible presence of mRNAs in skin surface lipids (SSLs). We found that measurable levels of human mRNAs exist in SSLs, where the sebum protects them from degradation by RNases. The AmpliSeq transcriptome analysis was modified to measure SSL-RNA levels, and our results revealed that the SSL-RNAs predominantly comprised mRNAs derived from sebaceous glands, the epidermis, and hair follicles. Analysis of SSL-RNAs non-invasively collected from patients with atopic dermatitis revealed increased expression of inflammation-related genes and decreased expression of terminal differentiation-related genes, consistent with the results of previous reports. Further, we found that lipid synthesis-related genes were downregulated in the sebaceous glands of patients with atopic dermatitis. These results indicate that the analysis of SSL-RNAs is a promising strategy to understand the pathophysiology of skin diseases.

Inoue et al develop a non-invasive method of analyzing human skin mRNA using RNA in skin surface lipids collected with oil-blotting films. The authors outline the validation of this methodology and describe an application to determine transcriptome in skin surface lipids in patients with atopic dermatitis versus healthy skin.

The combination of hair follicle-specific marker LHX2 and co-expressed marker can distinguish between sweat gland placodes and hair placodes in rat

Eccrine sweat gland (ESG) and hair follicle (HF) are different skin appendages but share many common development characteristics. Although the morphology of adult ESG and HF is obviously different, it is difficult to distinguish ESG placodes from HFs placodes morphologically. To study the fate determination of ESG and HF, specific antigen markers for ESG placodes and HF placodes must be found first to distinguish them. In the study, we detected the expression of commonly used keratins 4, 5, 7-10, 12, 14, 15, 17-20, 27 and 73, and the reported ESG and HF specific markers, P-cadherin, Lymphoid enhancer factor 1 (LEF1), LIM Homeobox gene 2 (LHX2), Na⁺/K⁺-ATPase (NKA) and Na⁺-K⁺-2Cl^- cotransporter 1 (NKCC1) in ESG and HF placodes by single-immunofluorescence staining and double-immunofluorescence staining. To further verify the results of immunofluorescence staining, Western blot (WB) was used to detect the differential antigen and some co-expressed antigens of ESG and HF placodes. The results showed that both ESG and HF placodes expressed K4/5/14/1517/18, P-cadherin and LEF1, neither expressed K7/8/9/10/12/19/20/27/73, NKA or NKCC1. HF placodes specifically expressed LHX2. Combination of LHX2 and co-expressed antigen K14, can distinguish ESG placodes from HF placodes. We conclude that LHX2 is a specific marker for HF placodes, and ESG placodes and HF placodes can be distinguished by double immunofluorescence staining of the specific marker LHX2 and the co-expressed markers, such as K4, K5, K14, K15, K17, K18, P-cadherin and LEF1.

Engrailed 1 coordinates cytoskeletal reorganization to induce myofibroblast differentiation

Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases, including systemic sclerosis. Here we show that Engrailed 1 (EN1) is reexpressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and in turn, EN1 mediates the profibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a profibrotic gene expression profile functionally related to cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the reorganization of cytoskeleton during myofibroblast differentiation, in both standard fibroblast culture systems and in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.

Weighted gene co-expression network analysis of the association between upregulated AMD1, EN1 and VGLL1 and the progression and poor prognosis of breast cancer

Breast cancer is the most prevalent malignancy among females, but the molecular mechanisms involved in its pathogenesis and progression have remained to be fully elucidated. The aim of the present study was to identify novel potential therapeutic targets for breast cancer. The dataset GSE76275 was downloaded from the Gene Expression Omnibus database and weighted gene co-expression network analysis (WGCNA) was performed to identify hub genes. Furthermore, the dataset GSE25055, containing gene expression data and clinical information, was downloaded to validate the expression and survival association of these hub genes. In addition, the datasets GSE25065 and GSE42568 were used to validate the association between hub gene expression levels and clinical features. Immunohistochemistry (IHC), reverse transcription-quantitative PCR, as well as proliferation, migration, invasion and apoptosis assays, were used to verify gene expression and function. A total of 4,052 genes were selected for WGCNA and 18 modules were established; the red module was identified as the key module, as it had a strong positive correlation with the tumor grade. Survival analyses of hub genes [S-adenosylmethionine decarboxylase proenzyme (AMD1), homeobox protein engrailed-1 (EN1) and vestigial-like protein (VGLL1)] indicated that higher levels of gene expression were associated with poor prognosis of patients with breast cancer. This association was based on survival analysis of GSE25055 using the Kaplan-Meier plotter tool. Expression validation revealed that the upregulation of hub genes was associated with advanced tumor grade and malignant molecular subtype (basal-like). IHC results from the Human Protein Atlas also demonstrated that protein expression levels of the hub genes were higher in tumor tissues compared with those in adjacent normal tissues. Furthermore, the expression levels of AMD1, EN1 and VGLL1 were strongly correlated with each other. These results demonstrated that AMD1 is highly expressed in breast cancer tissues and cells and AMD1 knockdown decreased the proliferation and metastatic potential, while increasing apoptosis of breast cancer cells. These results suggested that AMD1, EN1 and VGLL1 are likely to contribute to breast cancer progression and unfavorable prognosis.

Homeobox transcription factor engrailed homeobox 1 is a possible diagnostic marker for adenoid cystic carcinoma and polymorphous adenocarcinoma

Diagnostic utility of a homeobox transcription factor, engrailed homeobox 1 (En1) in the histopathology of salivary gland neoplasms was studied. The expression of En1 was immunohistochemically examined in 51 cases of adenoid cystic carcinoma (AdCC) and 143 cases of other salivary gland neoplasms. In all 51 AdCCs, En1 was expressed in 30-100% of tumor cells. In eight of nine polymorphous adenocarcinomas (PACs), En1 was expressed in 40-100% of tumor cells. Less than 5% of tumor cells expressed En1 in three of 12 epithelial-myoepithelial carcinomas, one of 17 basal cell adenomas (BCAs), and one of 34 pleomorphic adenomas (PAs). Among 55 other carcinoma cases, 1-30% of tumor cells expressed En1 in three salivary duct carcinomas (SDCs) ex PA. None of the myoepitheliomas and Warthin tumors expressed En1. When the cut-off value of the percentage of En1-expressing cells was set to 25%, all 51 AdCCs, eight of nine PACs and one SDC ex PA were En1-positive and the others were En1-negative. En1 is expressed consistently in AdCCs, frequently in PACs, but rarely in other salivary gland neoplasms. En1 is a possible diagnostic marker for AdCC and PAC in the histopathology of salivary gland neoplasms.

Engrailed Homeobox 1 and Cytokeratin 19 Are Independent Diagnostic Markers of Eccrine Porocarcinoma and Distinguish It From Squamous Cell Carcinoma

OBJECTIVES

The diagnostic utility of En1 in the histopathologic differentiation of eccrine porocarcinoma (EPC) from invasive squamous cell carcinoma (SCC) was investigated.

METHODS

Expression of En1 and CK19 in 16 cases of EPC was immunohistochemically examined and compared with that in 32 cases of SCC.

RESULTS

In all 16 EPCs, En1 was expressed in 3% to 100% of tumor cells. In 20 of the 32 SCCs, En1 was expressed in 3% to 90% of tumor cells. A total of 13 of the 16 EPCs and five of the 32 SCCs were judged as En1 positive, with a cutoff value of 25%. In addition, 11 of the 16 EPCs and four of the 32 SCCs were CK19 positive. The frequencies of En1- and CK19-positive cases were significantly higher in EPCs than in SCCs. In a logistic regression analysis for predicting EPC, En1 and CK19 were independent markers. When expression patterns of En1 and CK19 were combined, none of the 32 SCCs was both positive. In contrast, 15 of the 16 EPCs were positive for either En1 or CK19.

CONCLUSIONS

A combination of En1 and CK19 expression can improve the accuracy of histologic diagnosis of EPC.

Magnifying glass on spiradenoma and cylindroma histogenesis and tumorigenesis using systematic transcriptome analysis

Spiradenoma and cylindroma are related sweat gland tumors. To delineate their histogenesis, gene profiles, and their potential drivers, we performed a whole-transcriptome sequencing analysis of fourteen samples of spiradenoma/cylindroma in comparison to normal samples. A total of 12 spiradenomas, 5 cylindromas, 3 hybrid spiradenomas/cylindromas and 2 adnexal carcinomas were included in this study. 1335 characteristic genes and transcripts expressed over all 14 spiradenoma/cylindroma tumors were identified, and two groups of expression profiles were observed. Highest upregulated top 7 gene signatures characterized benign tumors with developmental and differentiation related genes, and carcinomas with top 7 genes mainly related to signaling, reorganization and metabolism of membranes. Immunohistochemistry of protein expressions validated 4 upregulated genes (ODAM, HOXB13, MYB and SOX10) considered important and as potential biomarkers for spiradenomas and cylindromas. We further compared the transcriptome of eccrine adnexal tumors with the transcriptome of adenoid cystic carcinoma (ACC) to identify the overlapping genes that may indicate histogenesis. There were 36 specific genes overlapping between adnexal carcinomas and the epithelial-dominant subtype of ACC, and 27 specific genes overlapping benign adnexal tumors with the myoepithelial-dominant subtype of ACC, At this point there is no known specific biomarker to aid in the diagnosis of eccrine spiradenoma and cylindroma in small samples or biopsies within the context of morphological overlap with ACC. In conclusion, spiradenomas and cylindromas are characterized by overexpressed developmental genes, where LHX2 and activated WNT signaling possibly drive associated carcinomas.