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

Genomic instability in congenital lung malformations in children

PURPOSE

To study the biological relationship between congenital lung malformations (CLMs) and malignancy.

METHODS

Biopsies of 12 CPAMs, 6 intralobar sequestrations and 2 extralobar sequestrations were analyzed through whole-genome sequencing. Blood samples from 10 patients were used to confirm or exclude somatic mosaicism. Putative somatic Single Nucleotide Variants (SNVs) were called for each malformed sample with a Panel of Normals built with control DNA samples extracted from blood. The variants were subsequently confirmed by Sanger sequencing and searched, whenever possible, in the blood samples of patients.

RESULTS

All CLMs but one presented a signature of genomic instability by means of multiple clusters of cells with gene mutations. Seven tumor transformation-related SNVs were detected in 6/20 congenital lung malformations. Four very rare in the general population SNVs were found in a region previously linked to lung cancer in 5p15.33, upstream of TERT oncogene. Furthermore, we identified missense genetic variants, whose tumorigenic role is well known, in the RET, FANCA and MET genes.

CONCLUSIONS

Genomic instability in 95% of CLMs and genetic variants linked to tumor development in 30% of them, regardless of histopathology, are predisposing factors to malignancy, that combined with exposure to carcinogens, might trigger the development of malignancy and explain the association between CLMs and lung cancer.

Invasive Mucinous Adenocarcinoma in a Newborn With Antenatally Diagnosed Congenital Pulmonary Airway Malformation: A Case Report

Congenital pulmonary airway malformations (CPAMs) are rare multicystic lung lesions typically diagnosed antenatally. We present a case of a term female neonate with antenatally diagnosed CPAM who required pleuro-amniotic shunting at 22 weeks of gestation. The patient was born with a right-sided pneumothorax and severe cardiorespiratory distress, necessitating extracorporeal membrane oxygenation (ECMO). Chest CT confirmed CPAM, revealing multiple cystic lesions in the right middle lobe and a significant contralateral mediastinal shift. On the second day of life, while on ECMO, the patient underwent a right middle lobectomy and an upper lobe anterior segmentectomy via a posterolateral thoracotomy. Post-surgery cardiac CT showed narrowing of the left pulmonary artery, although a perfusion study indicated normal left lung perfusion. Histopathological examination identified CPAM type 1 with invasive mucinous adenocarcinoma (IMA; stage 1: pT1b), featuring low-to-intermediate cellularity and KRAS G12D mutations. The invasive mucinous component measured at least 15 mm but did not invade the visceral pleura. After a gradual weaning process, the patient was successfully extubated and discharged home after 70 days. To our knowledge, this is the first reported case of CPAM type 1 with IMA that underwent pleuro-amniotic shunting in the second trimester.

The ten-year evaluation of clinical characteristics in congenital lung anomaly in pediatrics; a retrospective study in North of Iran

INTRODUCTION

Congenital lung anomalies (CLA) are a group of anomalies, including congenital cystic adenomatoid malformation (CCAM), bronchopulmonary sequestrations (BPS), congenital lobar emphysema (CLE), and bronchogenic cysts (BC). The prevalence of these rare anomalies has risen in recent years, according to various population-based studies due to advances in fetal ultrasound technology.

METHOD

This retrospective study examines the diagnosis of CLA, and was conducted on 72 patients between March 2014 and March 2024 at Taleghani Pediatric Hospital in Gorgan, Iran.

RESULT

The average age was 18.8 ± 30.3 months, with the majority being boys (62.5%). Most participants had CCAM (41.7%), followed by CLE (18.1%), BPS (16.7%), pulmonary hypoplasia (9.7%), BC (8.3%), and hybrid lesion (5.6%). The majority of patients were Fars (62.5%), and the average hospitalization days was 9.4 ± 4.5 days. Cardiac anomalies were observed in 19.4% of the patients. 62 patients (86.1%) exhibited respiratory symptoms, and prenatal screening during pregnancy led to the diagnosis in 51 patients (70.8%). Most patients had left lung anomalies (43; 59.7%), and the majority (90.3%) survived. There is a statistically significant relation between needed for surgical treatment and patients' type of pulmonary lesions (p-value: 0.02). In addition, there was a significant relation between the Fars ethnicity and the presence of cardiac anomalies (p-value: 0.04).

CONCLUSION

Some CLAs remain undiagnosed or untreated due to the rare nature of congenital lung anomalies. Nevertheless, improvements in ultrasound and other imaging methods will make diagnosing and managing these anomalies during the prenatal period more prevalent, resulting in enhanced understanding.

Congenital Lung Malformations: A Pictorial Review of Imaging Findings and a Practical Guide for Diagnosis

The term congenital lung malformation (CLM) is used to describe a wide range of pathological conditions with different imaging and clinical manifestations. These anomalies stem from abnormal embryological lung development, potentially occurring across various stages of prenatal life. Their natural history can be variable, presenting in a wide range of severity levels and encompassing asymptomatic individuals who remain so until adulthood, as well as those who experience respiratory distress in the neonatal period. Through the PubMed database, we performed an extensive review of the literature in the fields of congenital lung abnormalities, including their diagnostic approach and findings. From our RIS-PACS database, we have selected cases with a final diagnosis of congenital lung malformation. Different diagnostic approaches have been selected, including clinical cases studied using plain radiograph, CT scan, prenatal ultrasound, and MR images. The most encountered anomalies can be classified into three categories: bronchopulmonary anomalies (congenital pulmonary airway malformations (CPAMs), congenital lobar hyperinflation, bronchial atresia, and bronchogenic cysts), vascular anomalies (arteriovenous malformation), and combined lung and vascular anomalies (scimitar syndrome and bronchopulmonary sequestration). CLM causes significant morbidity and mortality; therefore, the recognition of these abnormalities is necessary for optimal prenatal counseling and early peri- and postnatal management. This pictorial review aims to report relevant imaging findings in order to offer some clues for differential diagnosis both for radiologists and pediatric consultants.

Pulmonary invasive mucinous adenocarcinoma

Invasive mucinous adenocarcinoma (IMA) is a relatively rare subtype of lung adenocarcinoma, composed of goblet and/or columnar tumour cells containing abundant intracytoplasmic mucin vacuoles. While a majority of IMAs are driven by KRAS mutations, recent studies have identified distinct genomic alterations, such as NRG1 and ERBB2 fusions. IMAs also more frequently present as a pneumonic-like pattern with multifocal and multilobar involvement, and comparative genomic profiling predominantly shows a clonal relationship, suggesting intrapulmonary metastases rather than synchronous primary tumours. Accordingly, these unique features require different therapeutic approaches when compared to nonmucinous adenocarcinomas in general. In this article, we review recent updates on the histopathological, clinical, and molecular features of IMAs, and also highlight some unresolved issues for future studies.

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.

Congenital lung malformations

Congenital lung malformations (CLMs) are rare developmental anomalies of the lung, including congenital pulmonary airway malformations (CPAM), bronchopulmonary sequestration, congenital lobar overinflation, bronchogenic cyst and isolated congenital bronchial atresia. CLMs occur in 4 out of 10,000 live births. Postnatal presentation ranges from an asymptomatic infant to respiratory failure. CLMs are typically diagnosed with antenatal ultrasonography and confirmed by chest CT angiography in the first few months of life. Although surgical treatment is the gold standard for symptomatic CLMs, a consensus on asymptomatic cases has not been reached. Resection, either thoracoscopically or through thoracotomy, minimizes the risk of local morbidity, including recurrent infections and pneumothorax, and avoids the risk of malignancies that have been associated with CPAM, bronchopulmonary sequestration and bronchogenic cyst. However, some surgeons suggest expectant management as the incidence of adverse outcomes, including malignancy, remains unknown. In either case, a planned follow-up and a proper transition to adult care are needed. The biological mechanisms through which some CLMs may trigger malignant transformation are under investigation. KRAS has already been confirmed to be somatically mutated in CPAM and other genetic susceptibilities linked to tumour development have been explored. By summarizing current progress in CLM diagnosis, management and molecular understanding we hope to highlight open questions that require urgent attention.

Defining the spatial landscape of KRAS mutated congenital pulmonary airway malformations: a distinct entity with a spectrum of histopathologic features

The potential pathogenetic mechanisms underlying the varied morphology of congenital pulmonary airway malformations (CPAMs) have not been molecularly determined, but a subset have been shown to contain clusters of mucinous cells (MCC). These clusters are believed to serve as precursors for potential invasive mucinous adenocarcinoma, and they are associated with KRAS codon 12 mutations. To assess the universality of KRAS mutations in MCCs, we sequenced exon 2 of KRAS in 61 MCCs from 18 patients, and we found a KRAS codon 12 mutation in all 61 MCCs. Furthermore, all MCCs from a single patient always had the same KRAS mutation, and the same KRAS mutation was also found in non-mucinous lesional tissue. Next generation sequencing of seven MCCs showed no other mutations or copy number variations. Sequencing of 46 additional CPAMs with MCCs revealed KRAS mutations in non-mucinous lesional tissue in all cases. RNA in situ hybridization confirmed widespread distribution of cells with mutant KRAS RNA, even extending outside of the bronchiolar type epithelium. We identified 25 additional CPAMs with overall histologic architecture similar to CPAMs with KRAS mutations but without identifiable MCCs, and we found KRAS mutations in 17 (68%). The histologic features of these KRAS mutated CPAMs included type 1 and type 3 morphology, as well as lesions with an intermediate histologic appearance, and analysis revealed a strong correlation between the specific amino acid substitution and histomorphology. These findings, together with previously published model organism data, suggests that the formation of type 1 and 3 CPAMs is driven by mosaic KRAS mutations arising in the lung epithelium early in development and places them within the growing field of mosaic RASopathies. The presence of widespread epithelial mutation explains late metastatic disease in incompletely resected patients and reinforces the recommendation for complete resection of these lesions.

Mucinous Adenocarcinoma With Intrapulmonary Metastasis Harboring KRAS and GNAS Mutations Arising in Congenital Pulmonary Airway Malformation

OBJECTIVES

Mucinous adenocarcinoma arising in unresected congenital pulmonary airway malformation (CPAM) is rare. Underlying driver mutations in addition to KRAS gain-of-function mutations in this setting and the long-term outcomes of these patients are unknown.

METHODS

We report a case of metastatic mucinous adenocarcinoma harboring both KRAS and GNAS mutations arising in a type 1 CPAM of a 14-year-old male. A literature review was performed.

RESULTS

Next-generation sequencing revealed identical KRAS (G12V) mutations in both the CPAM and metastatic adenocarcinoma and a missense mutation in the GNAS (R201C) gene in the metastatic adenocarcinoma only. Median survival was 23 and 4 years for patients with localized (no or limited spread within the same lobe of CPAM) and distant involvement (spread to any different lobe of CPAM) of mucinous cells, respectively (95% confidence interval, 23-23 and 1.5-22 years, respectively; P = .017).

CONCLUSIONS

Mucinous cell proliferation associated with type 1 CPAM has exceptionally good long-term outcomes if confined within the same lobe of CPAM. A second oncogenic mutation in the GNAS gene may be necessary for progression to malignancy and distant spread.

Whole-Genome Methylation Study of Congenital Lung Malformations in Children

Background and Objectives

The treatment of asymptomatic patients with congenital pulmonary malformations (CPMs) remains controversial, partially because the relationship between congenital lung malformations and malignancy is still undefined. Change in methylation pattern is a crucial event in human cancer, including lung cancer. We therefore studied all differentially methylated regions (DMRs) in a series of CPMs in an attempt to find methylation anomalies in genes already described in association with malignancy.

Methods

The DNA extracted from resected congenital lung malformations and control lung tissue was screened using Illumina MethylationEPIC arrays. Comparisons between the group of malformed samples or the malformed samples of same histology or each malformed sample and the controls and between a pleuropulmonary blastoma (PPB) and controls were performed. Moreover, each malformed sample was pairwise compared with its respective control. All differentially methylated regions (DMRs) with an adjusted p-value <0,05 were studied.

Results

Every comparison highlighted a number of DMRs closed to genes involved either in cell proliferation or in embryonic development or included in the Cancer Gene Census. Their abnormal methylation had been already described in lung tumors.

Conclusions

Methylation anomalies already described in lung tumors and also shared by the PPB were found in congenital lung malformations, regardless the histology. The presence of methylation abnormalities is suggestive of a correlation between congenital lung malformations and some step of malignant transformation.

Primary Lung Cribriform Adenocarcinoma With Squamoid Morules Harboring Somatic CTNNB1 Mutation in a Never-Smoked Healthy Adolescent

Primary lung adenocarcinomas are rare in pediatric patients, and even rarer in patients without precedent malignancy or congenital malformation. Here we present the first reported case of primary lung cribriform adenocarcinoma with squamoid morules in a previously healthy adolescent female. Molecular testing identified CTNNB1 mutation in the tumor and excluded other common mutations in lung adenocarcinoma. Our case suggests molecular alterations to the same signaling pathway can lead to similar histomorphology regardless of the tissue of origin.

Mucinous adenocarcinoma arising in congenital pulmonary airway malformation: clinicopathological analysis of 37 cases

AIMS

Mucinous adenocarcinoma arising in congenital pulmonary airway malformation (CPAM) is a rare complication, with little being known about its natural course. The aims of this article are to describe a series of mucinous adenocarcinomas arising from CPAMs, and present their clinicopathological features, genetics, and clinical outcome.

METHODS AND RESULTS

Thirty-seven cases were collected within a 34-year period, and the subtype of adenocarcinoma and CPAM, tumour location, stage, growth patterns, molecular data and follow-up were recorded. The cohort comprised CPAM type 1 (n = 33) and CPAM type 2 (n = 4). Morphologically, 34 cases were mucinous adenocarcinomas (21 in situ; 13 invasive), and three were mixed mucinous and non-mucinous adenocarcinoma. Seventeen cases showed purely extracystic (intra-alveolar) adenocarcinoma, 15 were mixed intracystic and extracystic, and five showed purely intracystic proliferation. Genetically, nine of 10 cases tested positive for KRAS mutations, four with exon 2 G12V mutation and five with exon 2 G12D mutation. Residual disease on completion lobectomy was observed in two cases, and three cases recurred 7, 15 and 32 years after the original diagnosis. Two patients died of metastatic invasive mucinous adenocarcinoma.

CONCLUSIONS

Most adenocarcinoma that arise in type 1 CPAMs, are purely mucinous, and are early-stage disease. Intracystic proliferation is associated with lepidic growth, an absence of invasion, and indolent behaviour, whereas extracystic proliferation may be associated with more aggressive behaviour and advanced stage. Most cases are cured by lobectomy, and recurrence/residual disease seems to be associated with limited surgery. Long-term follow-up is needed, as recurrence can occur decades later.

Mucinous Cell Clusters in Infantile Congenital Pulmonary Airway Malformations Mimic Adult Mucinous Adenocarcinoma But Are Not Associated With Poor Outcomes When Appropriately Resected

Congenital pulmonary airway malformations (CPAMs) are abnormalities of the lung arising during development. At our institution the majority of type I infantile CPAMs contain mucinous cell clusters (MCCs). The overlapping histology of MCCs and adult in situ mucinous adenocarcinomas, as well as reports of metastatic mucinous adenocarcinoma arising in CPAMs resected later in childhood raise concerns about the malignant potential of these cells. However, after adequate surgical resection, malignant recurrence has not been reported in infants with CPAMs. Despite benign behavior, MCCs often have histologic features that, in an adult, would be consistent with a diagnosis of adenocarcinoma. Therefore, to assess the spectrum of features that may be seen in these presumed precursor lesions, we characterized the histology of 671 MCCs spread across 44 infantile CPAMs and compared them to 10 adult mucinous adenocarcinomas. MCCs in CPAMS were often numerous, widespread, and located outside of the large cysts. Mucinous and nonmucinous epithelium within CPAMs showed complex architecture, making application of adult adenocarcinoma architectural patterns difficult. The MCCs within CPAMs displayed nuclear features similar to adult mucinous adenocarcinomas. The proliferative index in infantile MCCs was higher than in adult mucinous adenocarcinomas but was also higher in uninvolved infantile lung tissue. This work illustrates that histologic features typically associated with adenocarcinoma frequently occur within CPAMs; however, this does not alter their benign behavior. Therefore, extreme caution should be used if adult lung cancer terminology is applied to avoid significant potential psychological and physical harms associated with the label of adenocarcinoma.

Mechanism of lung development in the aetiology of adult congenital pulmonary airway malformations

Congenital pulmonary airway malformations (CPAMs) are rare lung abnormalities that result in cyst formation and are associated with respiratory distress in infants and malignant potential in adults. The pathogenesis of CPAMs remains unknown but data suggest disruption of the normal proximo-distal programme of airway branching and differentiation. Here, we demonstrate that adult human CPAM are lined with epithelium that retains SOX-2 and thyroid transcription factor-1 immunohistochemical markers, characteristic of the developing lung. However, RALDH-1, another key marker, is absent. This suggests a more complex aetiology for CPAM than complete focal arrest of lung development and may provide insight to the associated risk of malignancy.

Early KRAS oncogenic driver mutations in nonmucinous tissue of congenital pulmonary airway malformations as an indicator of potential malignant behavior

The potential for malignant degeneration is the most common reason for some practitioners to resect asymptomatic congenital pulmonary airway malformations (CPAMs). We aimed to investigate the potential of various immunohistochemical (IHC) and genomic biomarkers to predict the presence of mucinous proliferations (MPs) in CPAM. Archival CPAM tissue samples were re-assessed and underwent IHC analysis using a panel of differentiating markers (TTF1/CDX2/CC10/MUC2/MUC5AC/p16/p53/DICER1). In each sample, intensity of IHC staining was assessed separately in normal lung tissue, CPAM, and MP tissue, using a semiquantitative approach. Likewise, next-generation targeted sequencing of known adult lung driver mutations, including KRAS/BRAF/EGFR/ERBB2, was performed in all samples with MP and in control samples of CPAM tissue without MP. We analyzed samples of 25 CPAM type 1 and 25 CPAM type 2 and found MPs in 11 samples. They were all characterized by strong MUC5AC expression, and all carried a KRAS mutation in the MP and adjacent nonmucinous CPAM tissue, whereas the surrounding normal lung tissue was negative. By contrast, in less than half (5 out of 12) control samples lacking MP, the CPAM tissue also carried a KRAS mutation. KRAS mutations in nonmucinous CPAM tissue may identify lesions with a potential for malignant degeneration and may guide histopathological assessment and patient follow-up.

Atypical goblet cell hyperplasia occurs in CPAM 1, 2, and 3, and is a probable precursor lesion for childhood adenocarcinoma

Congenital pulmonary airway malformation (CPAM) is a developmental disorder. Types 1-2-3 are the more common ones. Atypical goblet cell hyperplasia (AGCH) in CPAM might be a precursor lesion for pulmonary adenocarcinomas. In nine out of 33 CPAM cases, types 1-3 showed foci of goblet cell proliferations. As these cells completely replace normal epithelium, we prefer to name these proliferations AGCH. In 5 cases, adenocarcinomas were seen (AC). All cases were analyzed for proteins possibly being associated with CPAM development: fibroblast growth factor 10 (FGF10) and receptor 2 (FGFR2), forkhead box A1 (FOXA1) and A2 (FOXA2), MUC protein 5AC (MUC5AC), human epidermal growth factor receptor 2 (erbB2, HER2/neu), hepatocyte nuclear factor 4α (HNF4α), SOX2, and Ying Yang protein 1 (YY1). By next generation sequencing, AGCH and adenocarcinomas were evaluated for driver mutations. Expression for FGF10, FGFR2, FOXA1, and FOXA2 was seen in CPAM epithelium and stroma, but not differently in AGCH and AC. SOX2 was positive in CPAM epithelium and AGCH, however weakly in AC. YY1 and MUC5AC showed more intense staining in AGCH and AC than in CPAM epithelium. HER2 was intensely expressed in AC and less intensely in AGCH, but not in CPAM epithelium. KRAS mutation in exon 2 was detected in all AGCH and AC, but was absent in CPAM epithelia. AGCH can arise in CPAM types 1-3. Oncogenic KRAS mutation seems to be the oncogenic driver already in AGCH, proving its role as a precursor lesion for adenocarcinoma. It might upregulate HER2 at the protein level. YY1 seems to be involved in carcinogenesis.

Congenital Lung Malformations: Unresolved Issues and Unanswered Questions

Advances in prenatal and postnatal diagnosis, perioperative management, and postoperative care have dramatically increased the number of scientific reports on congenital thoracic malformations (CTM). Nearly all CTM are detected prior to birth, generally by antenatal ultrasound. After delivery, most infants do well and remain asymptomatic for a long time. However, complications may occur beyond infancy, including in adolescence and adulthood. Prenatal diagnosis is sometimes missed and detection may occur later, either by chance or because of unexplained recurrent or persistent respiratory symptoms or signs, with difficult implications for family counseling and substantial delay in surgical planning. Although landmark studies have been published, postnatal management of asymptomatic children is still controversial and needs a resolution. Our aim is to provide a focused overview on a number of unresolved issues arising from the lack of an evidence-based consensus on the management of patients with CTM. We summarized findings from current literature, with a particular emphasis on the vigorous controversies on the type and timing of diagnostic procedures, treatments and the still obscure relationship between CTM and malignancies, a matter of great concern for both families and physicians. We also present an algorithm for the assessment and follow-up of CTM detected either in the antenatal or postnatal period. A standardized approach across Europe, based on a multidisciplinary team, is urgently needed for achieving an evidence-based management protocol for CTM.

Case of mucinous adenocarcinoma of the lung associated with congenital pulmonary airway malformation in a neonate

Congenital pulmonary airway malformation (CPAM), previously known as congenital cystic adenomatoid malformation, is a rare developmental lung abnormality associated with rhabdomyosarcoma, pleuropulmonary blastoma, and mucinous adenocarcinoma of the lung. We report an unusual case of a 10-day-old male newborn with a left lower lobe pulmonary cyst who underwent lobectomy, which revealed type II CPAM complicated by multifocal mucinous adenocarcinoma. KRAS sequencing revealed a somatic mutation in Codon12 (GGT → GAT), suggesting the development of a mucinous adenocarcinoma in the background of mucinous metaplasia. Mucinous adenocarcinoma is the most common lung tumor associated with CPAM, but it generally occurs in older children and adults. Further, all cases in the literature are of type I CPAM. This case in a neonate indicates that malignant transformation can occur very early in type II CPAM.

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.

Pulmonary adenocarcinoma with mucin production modulates phenotype according to common genetic traits: a reappraisal of mucinous adenocarcinoma and colloid adenocarcinoma

Whether invasive mucinous adenocarcinoma (IMA) and colloid adenocarcinoma (ICA) of the lung represent separate tumour entities, or simply lie within a spectrum of phenotypic variability, is worth investigating. Fifteen ICA, 12 IMA, 9 ALK‐rearranged adenocarcinomas (ALKA), 8 non‐mucinous KRAS‐mutated adenocarcinomas (KRASA) and 9 mucinous breast adenocarcinomas (MBA) were assessed by immunohistochemistry for alveolar (TTF1, cytoplasmic MUC1), intestinal (CDX‐2, MUC2), gastric (membrane MUC1, MUC6), bronchial (MUC5AC), mesenchymal (vimentin), neuroendocrine (chromogranin A, synaptophysin), sex steroid hormone‐related (oestrogen and progesterone receptors), pan‐mucinous (HNF4A) and pan‐epithelial (keratin 7) lineage biomarkers and by targeted next generation sequencing (TNGS) for 50 recurrently altered cancer genes. Unsupervised clustering analysis using molecular features identified cluster 1 (IMA and ICA), cluster 2 (ALKA and KRASA) and cluster 3 (MBA) (p < 0.0001). Cluster 1 showed four histology‐independent sub‐clusters (S1 to S4) pooled by HFN4A and MUC5AC but diversely reacting for TTF1, MUC1, MUC2, MUC6 and CDX2. Sub‐cluster S1 predominantly featured intestinal‐alveolar, S2 gastrointestinal, S3 gastric and S4 alveolar differentiation. In turn, KRASA and ALKA shared alveolar lineage alongside residual MUC5AC expression, with additional focal CDX2 and diffuse vimentin, respectively. A proximal‐to‐distal scheme extending from terminal (TB) and respiratory (RB) bronchioles to alveolar cells was devised, where S3 originated from distal TB (cellular mucinous adenocarcinoma), S2 from proximal RB (secreting mucinous adenocarcinoma), S1 from intermediate RB (mucin lake‐forming colloid adenocarcinoma), S4 from distal RB (colloid alveolar adenocarcinoma), KRASA from juxta‐alveolar RB (KRAS‐mutated non‐mucinous adenocarcinoma) and ALKA from juxta‐bronchial alveolar cells (ALK‐translocated adenocarcinoma). TNGS analysis showed KRAS, LKB1, TP53, APC and CDKN2A mutation predominance. In conclusion, IMA and ICA are basket categories, which likely originate from distinct domains of stem/progenitor cells spatially distributed along bronchioles upon common molecular features and genetic alterations.

Association between Congenital Lung Malformations and Lung Tumors in Children and Adults: A Systematic Review

INTRODUCTION

The appropriate management of asymptomatic congenital pulmonary malformations (CPMs) remains controversial. Prophylactic surgery is recommended to avoid the risk for development of pulmonary infections and to prevent the highly debated development of malignancy. However, the true risk for development of malignancy remains unknown. A systematic review analyzed all cases in which lung tumors associated with CPMs in both the pediatric and adult populations were described.

METHODS

A comprehensive literature search was carried out; it included all the cases in which an association between CPMs and malignant pulmonary lesions was reported.

RESULTS

In all, 134 publications were eligible for inclusion. In 168 patients CPM was found associated with lung tumor. The diagnosis was made in 76 children at a mean age of 3.68 ± 3.4, whereas in the adult population (n = 92) it was made at a mean age of 44.62 ± 16.09. Cough was the most frequent presenting symptom both in children and in adults. Most of the patients underwent lobectomy. The tumor most often associated with CPM was pleuropulmonary bastoma in children (n = 31) and adenocarcinoma (n = 20) or bronchioloalveolar carcinoma (n = 20) in adults. The CPM most frequenty associated with tumors in children was congenital cystic adenomatoid malformation (n = 37), especially type 1 (n = 21), whereas in adults it was bronchogenic cyst (n = 25), followed by congenital cystic adenomatoid malformation (n = 21).

CONCLUSIONS

CPMs should be followed up and never underestimated because they may conceal a tumor. Apparently, there is no age limit for malignant progression of CPMs and no limit of the interval between first detection of the CPM and appearance of the associated tumor.

Risk-reduction surgery in pediatric surgical oncology: A perspective

OBJECTIVE

A small percentage of pediatric solid cancers arise as a result of clearly identified inherited predisposition syndromes and nongenetic lesions. Evidence supports preemptive surgery for children with genetic [multiple endocrine neoplasia type 2 (MEN2), familial adenomatous polyposis syndrome (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), and hereditary diffuse gastric cancer (HDGC) and nongenetic [thyroglossal duct cysts (TGDC), congenital pulmonary airway malformations (CPAM), alimentary tract duplication cysts (ATDC), and congenital choledochal cysts (CCC)] developmental anomalies. Our aim was to explore the utility of risk reduction surgery to treat and prevent cancer in children.

METHODS

A systematic review of the available peer-reviewed literature on PubMed was performed using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) search strategy, where possible. Search items included "risk reduction surgery", "hereditary cancer predisposition syndrome", "multiple endocrine neoplasia type 2", "familial adenomatous polyposis", "hereditary nonpolyposis colorectal cancer", "hereditary diffuse gastric cancer", "thyroglossal duct cysts", congenital pulmonary airway malformations", "alimentary tract duplication cysts", "malignant transformation", and "guidelines".

RESULTS

We identified 67 articles that met the inclusion criteria describing the indications for prophylactic surgery in surgical oncology. For the genetic predisposition syndromes, 7 studies were related to professional endorsed guidelines, 7 were related to surgery for MEN2, 11 were related to colectomy for FAP, 6 were related to colectomy for HNPCC, and 12 related to gastrectomy for HDGC. Articles for the nongenetic lesions included 5 for techniques related to TGDC resection, 9 for surgery for CPAMs, and 10 for resection of ATDCs. Guidelines and strategies varied significantly especially related to the extent and timing of surgical intervention; the exception was for the timing of thyroidectomy in children with MEN2.

CONCLUSION

Current evidence supporting prophylactic surgery in the management of pediatric cancer predisposition syndromes and nongenetic lesions is best delineated for thyroidectomy to prevent medullary thyroid cancer in children with MEN2 (Strength of Recommendation Grade B/C). Despite the lack of pediatric specific evidence-based recommendations regarding the appropriate extent and timing for risk-reduction surgery for FAP, HNPCC, HDGC and nongenetic anomalies, our review represents an opportunity towards understanding the postgenomic development of these lesions and provides current indications and techniques for preemptive cancer prevention surgery in children.

MUC5AC interactions with integrin β4 enhances the migration of lung cancer cells through FAK signaling

MUC5AC is a secretory mucin aberrantly expressed in various cancers. In lung cancer, MUC5AC is overexpressed in both primary and metastatic lesions; however, its functional role is not well understood. The present study was aimed at evaluating mechanistic role of MUC5AC on metastasis of lung cancer cells. Clinically, the overexpression of MUC5AC was observed in lung cancer patient tissues and was associated with poor survival. In addition, the overexpression of Muc5ac was also observed in genetically engineered mouse lung adenocarcinoma tissues (Kras(G12D); Trp53(R172H/+); AdCre) in comparison with normal lung tissues. Our functional studies showed that MUC5AC knockdown resulted in significantly decreased migration in two lung cancer cell lines (A549 and H1437) as compared with scramble cells. Expression of integrins (α5, β1, β3, β4 and β5) was decreased in MUC5AC knockdown cells. As both integrins and MUC5AC have a von Willebrand factor domain, we assessed for possible interaction of MUC5AC and integrins in lung cancer cells. MUC5AC strongly interacted only with integrin β4. The co-localization of MUC5AC and integrin β4 was observed both in A549 lung cancer cells as well as genetically engineered mouse adenocarcinoma tissues. Activated integrins recruit focal adhesion kinase (FAK) that mediates metastatic downstream signaling pathways. Phosphorylation of FAK (Y397) was decreased in MUC5AC knockdown cells. MUC5AC/integrin β4/FAK-mediated lung cancer cell migration was confirmed through experiments utilizing a phosphorylation (Y397)-specific FAK inhibitor. In conclusion, overexpression of MUC5AC is a poor prognostic marker in lung cancer. MUC5AC interacts with integrin β4 that mediates phosphorylation of FAK at Y397 leading to lung cancer cell migration.

Genes associated with MUC5AC expression in small airway epithelium of human smokers and non-smokers

Background

Mucus hypersecretion contributes to the morbidity and mortality of smoking-related lung diseases, especially chronic obstructive pulmonary disease (COPD), which starts in the small airways. Despite progress in animal studies, the genes and their expression pattern involved in mucus production and secretion in human airway epithelium are not well understood. We hypothesized that comparison of the transcriptomes of the small airway epithelium of individuals that express high vs low levels of MUC5AC, the major macromolecular component of airway mucus, could be used as a probe to identify the genes related to human small airway mucus production/secretion.

Methods

Flexible bronchoscopy and brushing were used to obtain small airway epithelium (10^th to 12^th order bronchi) from healthy nonsmokers (n=60) and healthy smokers (n=72). Affymetrix HG-U133 plus 2.0 microarrays were used to assess gene expression. Massive parallel sequencing (RNA-Seq) was used to verify gene expression of small airway epithelium from 5 nonsmokers and 6 smokers.

Results

MUC5AC expression varied 31-fold among the healthy nonsmokers. Genome-wide comparison between healthy nonsmokers (n = 60) grouped as “high MUC5AC expressors” vs “low MUC5AC expressors” identified 528 genes significantly up-regulated and 15 genes significantly down-regulated in the high vs low expressors. This strategy identified both mucus production and secretion related genes under control of a network composed of multiple transcription factors. Based on the literature, genes in the up-regulated list were used to identify a 73 “MUC5AC-associated core gene” list with 9 categories: mucus component; mucus-producing cell differentiation-related transcription factor; mucus-producing cell differentiation-related pathway or mediator; post-translational modification of mucin; vesicle transport; endoplasmic reticulum stress-related; secretory granule-associated; mucus secretion-related regulator and mucus hypersecretory-related ion channel. As a validation cohort, we assessed the MUC5AC-associated core gene list in the small airway epithelium of an independent set of healthy smokers (n = 72). There was up-regulation of MUC5AC in the small airway epithelium of smokers (2.3-fold, p < 10^-8) associated with a coordinated up-regulation of MUC5AC-associated core gene expression pattern in the small airway epithelium of smokers (p < 0.01). Deep sequencing confirmed these observations.

Conclusion

The identification of the genes associated with increased airway mucin production in humans should be useful in understanding the pathogenesis of airway mucus hypersecretion and identifying therapeutic targets.

Author summary

Mucus hypersecretion contributes to the morbidity and mortality of smoking-related lung diseases, especially chronic obstructive pulmonary disease (COPD), which starts in the small airways. Little is known about the gene networks associated with the synthesis and secretion of mucins in the human small airway epithelium. Taking advantage of the knowledge that MUC5AC is a major mucin secreted by the small airway epithelium, the expression of MUC5AC in small airway epithelium is highly regulated at the transcriptional level and our observation that healthy nonsmokers have variable numbers of MUC5AC⁺ secretory cells in the human small airway epithelium, we compared genome-wide gene expression of the small airway epithelium of high vs low MUC5AC expressors from 60 nonsmokers to identify the genes associated with MUC5AC expression. This novel strategy enabled identification of a 73 “MUC5AC-associated core gene” list with 9 categories, which control a series of processes from mucin biosynthesis to mucus secretion. The coordinated gene expression pattern of MUC5AC-associated core genes were corroborated in an independent cohort of 72 healthy smokers. Deep sequencing of small airway epithelium RNA confirmed these observations. This finding will be useful in identifying therapeutic targets to treat small airway mucus hypersecretion.