Notch activation leads to loss of myoepithelial differentiation and poor outcome in solid adenoid cystic carcinoma

Survival Outcomes in Adenoid Cystic Carcinoma of the Head and Neck: A Systematic Review of 17 497 Cases and Meta-Analysis

BACKGROUND

Adenoid cystic carcinoma (ACC) is a slow-growing tumor with variable outcomes, making follow-up protocols challenging. This review analyzed outcomes in ACC, focusing on patterns and factors related to adverse prognoses.

METHODS

A search was conducted on March 25, 2024, in MEDLINE, PubMed, Scopus, and EMBASE. Studies analyzing ACC survival were included, while those lacking these data or focusing on a single ACC site were excluded. The Joanna Briggs Institute's Critical Appraisal tool was used to assess the risk of bias, and the metanalysis was performed using R software.

RESULTS

Among 57 studies (17 497 patients), ACC predominantly affected women (mean age: 52.69 years) and occurred mainly in minor salivary glands. Distant metastasis was the most frequent adverse outcome, occurring at 34.8 months on average. Locoregional metastasis and local recurrence occurred at 27.5 and 31.3 months, respectively. Five-, 10-, 15-, and 20-year survival rates were 73.8%, 48.5%, 42.3%, and 26.5%, respectively. Poor survival predictors included advanced T stage, positive lymph nodes, solid tumors, distant metastasis, and positive surgical margins.

CONCLUSIONS

Distant metastasis is the most frequent adverse outcome in ACC, and prognostic factors are related to advanced and residual tumors.

Molecular mapping in head and neck adenoid cystic carcinoma by pathological grade using whole-exome sequencing and spatial transcriptome

Our previous study demonstrated that pathological grades of adenoid cystic carcinoma (ACC) correlate with distinct prognoses and treatment strategies. To explore the molecular alterations underlying these grades, we performed whole-exome sequencing (WES) on 20 head and neck ACC samples from 12 patients, categorized into grade I-II, grade III, and high-grade transformation (HGT). Comprehensive analyses, including somatic mutations, chromosomal structural variations, and phylogenetic tree construction, were conducted. Spatial transcriptome (ST) technology was further employed to analyze gene expression, pseudo-time trajectories, and copy number variations in a grade III sample. WES revealed that high-grade (grade III and HGT) ACC tissues frequently harbor mutations in TP53, PI3K pathway genes, and chromatin remodelers. Phylogenetic analysis showed that higher-grade regions exhibit more subclonal mutations or a larger proportion of intergenerational mutations. Copy number analysis identified recurrent deletions of 1p36.33 and amplifications of 8q24.21/9p24.1 in high-grade samples, along with significant deletions on chr12 in both WES and ST. ST pathway enrichment and cell trajectory analyses indicated that high-grade clusters are more primitive and proliferative, while low-grade clusters display greater microenvironmental stability and interstitial specialization. These findings highlight the complex spatial heterogeneity associated with ACC pathological grades, providing critical insights into disease progression and guiding therapeutic strategies.

Heterogeneous immune landscapes and macrophage dynamics in primary and lung metastatic adenoid cystic carcinoma of the head and neck

Introduction

Recurrent or metastatic adenoid cystic carcinoma (ACC) of the head and neck is rare and highly aggressive. Due to the ineffectiveness of immune checkpoint therapies, this study aims to investigate the tumor immune microenvironment of primary tumor tissues and lung metastatic tissues and to comprehend the challenges of immunotherapy.

Methods

We analyzed RNA sequencing data and constructed immune landscapes from 25 primary tumors and 34 lung metastases. The data were then validated by immunohistochemistry and single-cell sequencing analysis.

Results

Compared to adjacent normal tissues, both primary and lung metastatic ACC showed low immune infiltration. Lung metastases had higher immune infiltration levels and antigen presentation scores but also higher T cell exclusion and dysfunction scores. Single-cell sequencing data and immunohistochemistry revealed abundant immunosuppressive tumor-associated macrophages in lung metastases. Patients with high M2 macrophage infiltration had shorter lung metastasis-free survival.

Discussion

Primary and lung metastatic ACC exhibit heterogeneous tumor immune microenvironments. Higher immune cell infiltration in lung metastases is countered by the presence of suppressive tumor-associated macrophages, which may limit effective anti-tumor responses.

Adenoid cystic carcinoma: insights from molecular characterization and therapeutic advances

Adenoid cystic carcinoma (ACC) is a malignant tumor primarily originating from the salivary glands, capable of affecting multiple organs. Although ACC typically exhibits slow growth, it is notorious for its propensity for neural invasion, local recurrence, and distant metastasis, making it a particularly challenging cancer to treat. The complexity of ACC's histological and molecular features poses significant challenges to current treatment modalities, which often show limited effectiveness. Recent advancements in single-cell RNA-sequencing (scRNA-seq) have begun to unravel unprecedented insights into the heterogeneity and subpopulation diversity within ACC, revealing distinct cellular phenotypes and origins. This review delves into the intricate pathological and molecular characteristics of ACC, focusing on recent therapeutic advancements. We particularly emphasize the insights gained from scRNA-seq studies that shed light on the cellular landscape of ACC, underscoring its heterogeneity and pathobiology. Moreover, by integrating analyses from public databases, this review proposes novel perspectives for advancing treatment strategies in ACC. This review contributes to the academic understanding of ACC by proposing novel therapeutic approaches informed by cutting-edge molecular insights, paving the way for more effective, personalized therapeutic approaches for this challenging malignancy.

Notch activation promotes bone metastasis via SPARC inhibition in adenoid cystic carcinoma

OBJECTIVES

We aimed to investigate bone metastasis induced by Notch signalling pathway dysregulation and to demonstrate that SPARC is a potential therapeutic target in adenoid cystic carcinoma (AdCC) with Notch dysregulation.

MATERIALS AND METHODS

This retrospective study enrolled 144 AdCC patients. RNA-sequencing and enrichment analyses were performed using 32 AdCC samples. Osteonectin/SPARC and the Notch activation indicator Notch intracellular domain (NICD) were detected using immunohistochemistry. Cell proliferation and migration assays were conducted using stably NICD over-expressing cells. The effect of SPARC on osteoclast differentiation in NICD cells was investigated using western blotting, quantitative reverse transcription PCR, tartrate-resistant acid phosphatase staining and resorption assays.

RESULTS

RNA-sequencing analysis showed that genes down-regulated in Notch-mutant AdCCs, such as SPARC, were enriched in ossification and osteoblast differentiation. Most (75/110, 68.2%) Notch1-wild-type AdCCs showed SPARC over-expression, whereas 30 out of 34 (88.2%) Notch1-mutant tumours showed low SPARC expression. SPARC over-expression was then found negatively to be correlated with NICD expression in 144 AdCCs. NICD over-expression promoted cell growth, migration and osteoclast differentiation, which could be partly reversed by exogenous SPARC.

CONCLUSIONS

Notch activation in AdCC contributes to bone metastasis through SPARC inhibition. The study results suggest that SPARC may represent a prognostic biomarker and potential therapeutic target.

Current diagnosis and treatment of salivary gland-type tumors of the lung

Salivary gland-type tumors of the lung are thought to originate from the submucosal exocrine glands of the large airways. Due to their rare occurrence, reports of their study are limited to small-scale or case reports. Therefore, daily clinical practices often require a search for previous reports. In the last 20 years, several genetic rearrangements have been identified, such as MYB::NF1B rearrangements in adenoid cystic carcinoma, CRTC1::MAML2 rearrangements in mucoepidermoid carcinoma, EWSR1::ATF1 rearrangements in hyalinizing clear cell carcinoma and rearrangements of the EWSR1 locus or FUS (TLS) locus in myoepithelioma and myoepithelial carcinoma. These molecular alterations have been useful in diagnosing these tumors, although they have not yet been linked to molecularly targeted therapies. The morphologic, immunophenotypic, and molecular characteristics of these tumors are similar to those of their counterparts of extrapulmonary origin, so clinical and radiologic differential diagnosis is required to distinguish between primary and metastatic disease of other primary sites. However, these molecular alterations can be useful in differentiating them from other primary lung cancer histologic types. The management of these tumors requires broad knowledge of the latest diagnostics, surgery, radiotherapy, bronchoscopic interventions, chemotherapy, immunotherapy as well as therapeutic agents in development, including molecularly targeted agents. This review provides a comprehensive overview of the current diagnosis and treatment of pulmonary salivary gland tumors, with a focus on adenoid cystic carcinoma and mucoepidermoid carcinoma, which are the two most common subtypes.

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.

Increased retinoic acid signaling decreases lung metastasis in salivary adenoid cystic carcinoma by inhibiting the noncanonical Notch1 pathway

MYB-NFIB fusion and NOTCH1 mutation are common hallmark genetic events in salivary gland adenoid cystic carcinoma (SACC). However, abnormal expression of MYB and NOTCH1 is also observed in patients without MYB-NFIB fusion and NOTCH1 mutation. Here, we explore in-depth the molecular mechanisms of lung metastasis through single-cell RNA sequencing (scRNA-seq) and exome target capture sequencing in two SACC patients without MYB-NFIB fusion and NOTCH1 mutation. Twenty-five types of cells in primary and metastatic tissues were identified via Seurat clustering and categorized into four main stages ranging from near-normal to cancer-based on the abundance of each cell cluster in normal tissue. In this context, we identified the Notch signaling pathway enrichment in almost all cancer cells; RNA velocity, trajectory, and sub-clustering analyses were performed to deeply investigate cancer progenitor-like cell clusters in primary tumor-associated lung metastases, and signature genes of progenitor-like cells were enriched in the "MYC_TARGETS_V2" gene set. In vitro, we detected the NICD1-MYB-MYC complex by co-immunoprecipitation (Co-IP) and incidentally identified retinoic acid (RA) as an endogenous antagonist of genes in the "MYC_TARGETS_V2" gene set. Following this, we confirmed that all-trans retinoic acid (ATRA) suppresses the lung metastasis of SACC by correcting erroneous cell differentiation mainly caused by aberrant NOTCH1 or MYB expression. Bioinformatic, RNA-seq, and immunohistochemical (IHC) analyses of primary tissues and metastatic lung tissues from patients with SACC suggested that RA system insufficiency partially promotes lung metastasis. These findings imply the value of the RA system in diagnosis and treatment.

Approaches to the Management of Metastatic Adenoid Cystic Carcinoma

High rates of recurrence and distant metastasis are a foremost challenge in the management of adenoid cystic carcinoma (ACC), occurring in approximately 40% of all ACC patients. Despite the morbidity and mortality resulting from recurrent/metastatic (R/M) disease, there are no FDA-approved systemic agents for these patients. In this review, we summarize pertinent ACC pathophysiology and its implications for different systemic treatment regimens in R/M ACC. We review the evidence for the most widely used systemic agents - cytotoxic chemotherapy and tyrosine kinase inhibitors (TKIs) targeting VEGFR - in addition to immune checkpoint inhibitors and non-TKI biologic agents. Exciting emerging targets for R/M ACC, including inhibitors of Notch signaling, stemness, PRMT5, and Axl, are also discussed. Lastly, we review local therapies for small-volume lung disease in patients with oligometastatic ACC, specifically pulmonary metastasectomy and stereotactic body radiation therapy (SBRT). Future development of targeted molecular agents which exploit the underlying biology of this disease may yield novel therapeutic options to improve clinical outcomes in patients with R/M ACC.

Adenoid Cystic Carcinoma from the salivary and lacrimal glands and the breast: different clinical outcomes to the same tumor

Adenoid cystic carcinoma (ACC) is a biphasic malignant lesion that can develop at various anatomical sites. Salivary and lacrimal ACC lesions have a high risk of local invasion, metastasis, and poor prognosis. In more distant organs, such as the breast, ACC is a rarer and less aggressive lesion. One of the major predictors of mortality of ACC is perineural invasion, which can be seen in 30% of breast lesions, 85% of salivary lesions, and almost 100% of lacrimal gland tumors. The biological differences between these three ACC tumors are still poorly understood. We focused on the current understanding of the genetic variations observed on ACC tumors and prognostic differences associated with distinct anatomical sites. A special effort was made to present the currently available therapies alongside the emerging strategies under development.

Genetic heterogeneity and therapeutic target detection through microdissection in solid-type adenoid cystic carcinoma

Solid-type adenoid cystic carcinomas (ACCs) are highly aggressive and heterogeneous tumours. Because of their rarity, therapeutic strategies guided by genetic profiles based on next generation sequencing (NGS) have not been published for these tumours. Forty-nine solid-type ACCs including 43 tumours with a predominantly solid pattern, and six tumours comprising a roughly equal mixture of cribriform/tubular and solid histological forms were included in our study. The solid components from the 49 solid ACCs were enriched for mutations of genes in the NOTCH pathway (NOTCH1 61%, SPEN 24%) and chromatin remodelling pathway and the absence of myoepithelial cell differentiation. Cases with NOTCH1 mutations exhibited strong NICD expression, which was associated with poor overall and distant metastasis free survival. BRCA2 mutation and BCOR/BCORL1 mutations were observed in 20% and 18.4% of solid ACCs, respectively. In six of the solid ACCs, intratumour heterogeneity was delineated between the cribriform/tubular and solid components. NOTCH1 and FGFR2 mutations as well as NOTCH2 amplification were restricted to the solid component, indicating clonal selection within the same tumour. In two recurrent/metastatic solid ACCs, the subclones evolved in progression for local relapse and distant metastasis, although they manifested close genomic resemblance to primary tumours. Guided by the genetic profiles, the preclinical efficiency of the gamma-secretase inhibitor BMS-906024 was evaluated in patient derived xenograft models (PDXs) with activating NOTCH1 mutations and demonstrated robust antitumour effects. Our report revealed intratumour heterogeneity among solid-types within an ACC as well as the inter-tumour evolution of dominant clones among two primary and recurrent/metastatic tumours. In contrast to cribriform/tubular ACCs, solid-type ACCs should be approached with a distinct therapeutic strategy, particularly targeting NOTCH1. Microdissecting the highest grade component guided by histology is a highly recommended tumour sampling strategy and facilitates the detection of key molecular targets.