Non-terminal respiratory unit type lung adenocarcinoma has three distinct subtypes and is associated with poor prognosis

Bilateral orthotopic lung transplantation for the patient with lung-limited invasive mucinous adenocarcinoma: a case-based literature review

Invasive mucinous adenocarcinoma (IMA) of lung is a unique subset of adenocarcinomas characterized by an intrapulmonary aerogenous spread resulting in multicentric, multilobar, and bilateral lesions with a low frequency of distant metastasis. The treatment options for IMA are limited, and advanced IMA has a poor prognosis, with a median survival of less than a year. Lung transplantation performed in a handful of selected patients showed improved survival outcomes and clinical improvement. However, high postoperative recurrence rates have been observed and recurrence appeared to originate from the primary tumor in many cases. Techniques, such as non-sequential double lung transplantation utilizing cardiopulmonary bypass, have been performed to reduce recurrence. Here, we present the first case of bilateral lung transplantation employing cardiopulmonary bypass in a patient with stage ⅣA lung-limited IMA without lymph node or distant metastasis. At 15 months post-transplantation, the patient remains stable with no evidence of disease recurrence or organ rejection. Additionally, we describe the classification, clinical outcomes, protein expression, and genetic characteristics of IMA. IMA was previously classified as a subset of bronchioalveolar carcinoma (BAC), which is invasive and mucinous with goblet or columnar cells secreting mucin. We reviewed and summarized the lung transplantation cases reported to date for BAC. The 5-year overall survival and disease-free survival have been reported approximately 50% (range, 39-100) and 50% (range, 35-100), respectively. The literature shows these outcomes are comparable to bilateral lung transplantation performed for non-cancerous pulmonary disease.

Establishment and characterization of novel high mucus-producing lung tumoroids derived from a patient with pulmonary solid adenocarcinoma

Among mucus-producing lung cancers, invasive mucinous adenocarcinoma of the lung is a rare and unique subtype of pulmonary adenocarcinoma. Notably, mucus production may also be observed in the five subtypes of adenocarcinoma grouped under the higher-level diagnosis of Invasive Non-mucinous Adenocarcinomas (NMA). Overlapping pathologic features in mucus-producing tumors can cause diagnostic confusion with significant clinical consequences. In this study, we established lung tumoroids, PDT-LUAD#99, from a patient with NMA and mucus production. The tumoroids were derived from the malignant pleural effusion of a patient with lung cancer and have been successfully developed for long-term culture (> 11 months). Karyotyping by fluorescence in situ hybridization using an alpha-satellite probe showed that tumoroids harbored aneuploid karyotypes. Subcutaneous inoculation of PDT-LUAD#99 lung tumoroids into immunodeficient mice resulted in tumor formation, suggesting that the tumoroids were derived from cancer. Xenografts from PDT-LUAD#99 lung tumoroids reproduced the solid adenocarcinoma with mucin production that was observed in the patient's metastatic lymph nodes. Immunoblot analysis showed MUC5AC secretion into the culture supernatant of PDT-LUAD#99 lung tumoroids, which in contradistinction was barely detected in the culture supernatants of NCI-A549 and NCI-H2122 pulmonary adenocarcinoma cells known for their mucin-producing abilities. Here, we established a novel high-mucus-producing lung tumoroids from a solid adenocarcinoma. This preclinical model may be useful for elucidating the pathogenesis of mucus-producing lung cancer.

A ciliated adenocarcinoma of the lung mimicking lung abscess and pneumonia

This case report describes a 78-year-old man initially treated for pneumonia and lung abscess who was resistant to antimicrobial treatment and was eventually diagnosed with ciliated adenocarcinoma. Ciliated adenocarcinoma, a rare non-terminal respiratory unit (TRU)-type lung adenocarcinoma, presents a unique diagnostic challenge because of its similarity to pneumonia and lung abscesses. Morphologically, the ciliated adenocarcinoma in this case appeared to be a non-TRU type adenocarcinoma, with partial mucous epithelium, no visible extracellular mucus, thyroid transcription factor (TTF)-1 negativity, and mucin (MUC) 5AC positivity on immunostaining. The patient was considered to have ciliated adenocarcinoma based on the fact that the mucous epithelium was partial and extracellular mucus was not prominent. This case emphasizes the importance of considering malignancy in patients with non-resolving pulmonary infections.

Clinicopathological features of cytokeratin 5-positive pulmonary adenocarcinoma

Cytokeratin 5 (CK5) is a marker for pulmonary squamous cell carcinoma; however, CK5 is sometimes present in pulmonary adenocarcinoma (ADC), and there is insufficient information regarding the clinicopathological features of CK5-positive ADC. We aimed to explore the clinicopathological characteristics of CK5-positive ADC using immunohistochemistry. We prepared the following two cohorts: a resected cohort containing 220 resected tumours for primarily studying the detailed morphological characteristics, and a tissue microarray (TMA) cohort containing 337 samples for investigating the associations of CK5 expression with other protein expressions, genetic and prognostic findings. CK5-positive ADC was defined to have ≥ 10% tumour cells and presence of CK5-positive tumour cells in the resected and TMA cohorts, respectively. CK5-positive ADCs were identified in 91 (16.3%) patients in the combined cohort. CK5-positive ADCs had male predominance (P = 0.012), smoking history (P = 0.001), higher stage (P < 0.001), histological high-grade components (P < 0.001), vascular invasion (P < 0.001), mucinous differentiation (P < 0.001), spread through airspaces (P < 0.001), EGFR wild-type (P < 0.001), KRAS mutations (P < 0.001), ALK rearrangement (P < 0.001) and ROS1 rearrangement (P = 0.002). In the resected cohort, more than half the CK5-positive ADCs (19 cases, 65.5%) showed mucinous differentiation; the remaining cases harboured high-grade components. In the TMA cohort, CK5-positive ADCs correlated with TTF-1 negativity (P = 0.002) and MUC5B, MUC5AC and HNF4alpha positivity (P < 0.001, 0.048, < 0.001). Further, CK5-positive ADCs had significantly lower disease-free and overall survival rates than CK5-negative ADCs (P < 0.001 for each). Additionally, multivariate analysis revealed that CK5 expression was an independent poor prognostic factor. CK5-positive ADCs showed aggressive clinical behaviour, with high-grade morphology and mucinous differentiation.

Gefitinib improves severe bronchorrhea and prolongs the survival of a patient with lung invasive mucinous adenocarcinoma: A case report

BACKGROUND

Lung invasive mucinous adenocarcinoma (LIMA), formerly referred to as mucinous bronchioloalveolar carcinoma, is a rare disease that usually presents as bilateral lung infiltration, is unsuitable for surgery and radiotherapy, and shows poor response to conventional chemotherapy.

CASE SUMMARY

We report a 56-year-old Chinese man with a history of smoking and epidermal growth factor receptor mutation-positivity who was initially misdiagnosed as severe pneumonia, but was ultimately diagnosed as a case of invasive mucinous adenocarcinoma of the lung by computed tomography -guided percutaneous lung biopsy. Bronchorrhea and dyspnea were improved within 24 h after initiation of gefitinib therapy and the radiographic signs of bilateral lung consolidation showed visible improvement within 30 d. After more than 11 months of treatment, there is no evidence of recurrence or severe adverse events.

CONCLUSION

Although the precise mechanism of the antitumor effects of gefitinib are not clear, our experience indicates an important role of the drug in LIMA and provides a reference for the diagnosis and treatment of this disease.

Comprehensive clinicopathological characteristics and mucin core protein expression profiles of bronchiolar adenoma

AIMS

Bronchiolar adenoma (BA) is a novel entity in the 2021 WHO classification of lung tumours. The expression profile of mucin core proteins in BAs is not clear. The aim of this study was to clarify the expression profiles of mucins and to validate the clinicopathologic and molecular features of BAs.

METHODS AND RESULTS

We examined the clinicopathological, immunohistochemical, and molecular features of 20 BAs. Our cohort comprised 10 proximal and 10 distal BAs. Only seven of 18 patients (39%) were accurately diagnosed with BA at the time of intraoperative consultation. The frequent genetic alterations were BRAF V600E (35%) and KRAS (30%) mutations, which were mutually exclusive. The expression of MUC1, MUC4, and MUC5B was observed in all cases and that of MUC5AC and MUC6 was observed in nine (45%) and five (25%) cases, respectively. MUC4 was diffusely expressed in 18 cases. In contrast, MUC1, MUC5AC, MUC5B, and MUC6 displayed a patchy expression pattern. These expression patterns were similar to that of bronchiolar epithelium in normal lung tissue. In addition, overexpression of MUC1 and MUC4 on the entire cell surface was not observed in any of the BAs, suggesting their benign nature.

CONCLUSION

BA commonly exhibits diffuse MUC4 and patchy MUC1 and MUC5B expression. Its unique expression pattern is probably attributed to mucin expression specific to the bronchiolar epithelium. These results confirm the clinicopathologic and molecular characteristics of BA, including the difficulty in intraoperative frozen section diagnosis and the broad morphologic spectrum of BA derived from the bronchiolar epithelium.

Gastric-type gene expression and phenotype in non-terminal respiratory unit type adenocarcinoma of the lung with invasive mucinous adenocarcinoma morphology

AIMS

We sought to determine if non-terminal respiratory unit (TRU) type adenocarcinoma of lung with invasive mucinous adenocarcinoma (IMA) morphology shows gastric differentiation.

METHODS AND RESULTS

We reviewed whole-section images of 489 cases of lung adenocarcinoma from The Cancer Genome Atlas (TCGA). TCGA data were classified into 426 TRU type adenocarcinoma, 49 IMA and 14 unclassifiable. Their RNA sequencing data was analysed by DESeq2 and WGCNA R packages. Gene expression in patients' samples was measured by NanoString assay. Overexpression of genes including REG4, TFF2, MUCL3, FER1L6, B3GALT5, ANXA10 was observed by TCGA analysis in IMA compared to TRU type adenocarcinoma. Many of these genes are those expressed in normal gastric glands and selected for NanoString experiment on 14 IMA and 10 TRU type adenocarcinoma cases. The expression of genes, including ANXA10, FER1L6, HNF4a, MUC5AC, REG4, TFF1, TFF2 and VSIGI, was increased> 15-fold in IMA. Immunohistochemistry of ANXA10, TFF2 and FER1L6 performed on 31 IMA and 135 TRU type adenocarcinomas showed a predominant expression in IMA, but are not in TRU type adenocarcinoma.

CONCLUSION

Our results showed the level of genes expressed in stomach mucosa was increased in IMA compared to TRU type adenocarcinoma, supporting gastric differentiation of IMA. This finding may help the understanding of the pathogenesis of IMA and discovery of therapeutic targets.

Discohesive growth pattern (Disco-p) as an unfavorable prognostic factor in lung adenocarcinoma: an analysis of 1062 Japanese patients with resected lung adenocarcinoma

Discohesive growth pattern (Disco-p) is often observed in lung adenocarcinoma (ADC) and mimics tumor budding (TB), stromal invasive-type micropapillary pattern (SMPP), and complex glandular pattern. However, the clinical impact of Disco-p in lung ADC has not been well studied. To investigate the prognostic significance of Disco-p, we analyzed 1062 Japanese patients with resected lung ADC. Disco-p was defined as an invasive growth pattern composed of single tumor cells, or trabeculae or small nests of tumor cells associated with desmoplastic fibrous stroma. We recorded the percentage of Disco-p in 5% increments independent of the major histologic pattern and investigated its correlation with different clinicopathological factors. We also analyzed the overall survival (OS) and disease-free survival (DFS). Disco-p was observed in 203 tumors (19.1%). Disco-p was significantly associated with male sex, smoking, lymph node metastasis, large tumor size, high TNM stage, lymphovascular and pleural invasion, spread through air spaces, and TB (all, p < 0.001). Of the total cases, only eight cases exhibited a dubious pattern between SMPP and Disco-p. Disco-p was also associated with wild-type EGFR (p < 0.001) and ALK fusion (p = 0.008). Patients harboring tumors with Disco-p had significantly worse prognoses (OS and DFS (both, p < 0.001)) compared with those without Disco-p. On multivariate analysis, Disco-p was an independent prognostic factor of worse OS (hazard ratio (HR), 2.572; 95% confidence interval (CI), 1.789-3.680; p < 0.001), and DFS (HR, 3.413; 95% CI, 2.482-4.683; p < 0.001), whereas TB was not an independent unfavorable prognostic factor. Disco-p was an independent unfavorable prognostic factor in patients with resected lung ADC, although a careful evaluation is necessary to distinguish it from similar patterns. We proposed that Disco-p should be recognized as a new invasive pattern and accurately recorded for the better management of patients with lung ADCs.

MUC5AC enhances tumor heterogeneity in lung adenocarcinoma with mucin production and is associated with poor prognosis

OBJECTIVE

The clinicopathological significance of Mucin5AC (MUC5AC) in lung adenocarcinoma with mucin production is still unclear. This study aimed to explore MUC5AC expression in lung adenocarcinoma with mucin production and its correlation with histological subtypes, common driver mutations and its impact on prognosis.

METHODS

MUC5AC and thyroid transcription factor 1 immunohistochemistry was performed on surgical samples from 90 patients with lung adenocarcinoma with mucin production. Common driver mutations including EGFR and KRAS mutations and ALK rearrangement were detected by established methods.

RESULTS

MUC5AC was significantly associated with lymphovascular invasion (P = 0.023) and tumors with intra-cytoplasmic mucin (P < 0.001). Moreover, MUC5AC was more significant in invasive mucinous adenocarcinoma (P < 0.001), as well as in tumors with KRAS mutations (P = 0.005) and a lack of thyroid transcription factor 1 expression (P < 0.001). Conversely, MUC5AC was less significantly detected in acinar predominant adenocarcinoma (P = 0.036) and tumors with EGFR mutations (P = 0.001). Notably, MUC5AC in non-pure mucinous subtype of lung adenocarcinoma with mucin production showed more aggressive behavior, distinct expression pattern and a lack of significant correlation with thyroid transcription factor 1 (P = 0.113) when compared with pure mucinous subtype. MUC5AC-positive tumors were significantly associated with a worse prognosis compared to MUC5AC-negative tumors (P < 0.001). A multivariate survival analysis showed that MUC5AC was an independent prognosis factor for poor prognosis (P = 0.006).

CONCLUSIONS

The clinicopathological features of non-pure mucinous subtype of lung adenocarcinoma with mucin production were distinct and should be distinguished from pure mucinous subtype. MUC5AC was associated with poor prognosis and could be a potential therapeutic target for this distinct type of lung adenocarcinoma that has few effective treatments.

Value of TTF-1 expression in non-squamous non-small-cell lung cancer for assessing docetaxel monotherapy after chemotherapy failure

Docetaxel is one of the standard second/third-line treatments for non-small-cell lung cancer (NSCLC) following a failed response to prior cytotoxic chemotherapy. The predictive biomarker for the effectiveness of docetaxel therapy remains undetermined. However, thyroid transcription factor-1 (TTF-1) is known to be a good prognostic factor for a variety of chemotherapies. To investigate the association between TTF-1 expression and docetaxel monotherapy outcome, 82 patients with non-squamous NSCLC who received second/third-line docetaxel monotherapy were retrospectively screened. All backgrounds were well-balanced whether or not tumor TTF-1 was expressed, and the present clinical outcomes were similar to those reported by previous clinical studies. A better clinical outcome was indicated in TTF-1 positive compared with TTF-1 negative patients, with disease control rates of 69% vs. 42%, respectively (P=0.03) and median overall survival of 393 days vs. 221.5 days, respectively (P<0.01). Furthermore, progression free survival tended to be longer in TTF-1 positive compared with TTF-1 negative patients (median, 100 days vs. 67 days; P=0.09). Multivariate analysis revealed that TTF-1 positivity was a unique significant predictor for assessing overall survival after docetaxel monotherapy. TTF-1 positivity may be useful for predicting survival outcome in patients who received docetaxel monotherapy after failure of prior chemotherapy.

Reciprocal expression of trefoil factor-1 and thyroid transcription factor-1 in lung adenocarcinomas

Molecular targeted therapies against EGFR and ALK have improved the quality of life of lung adenocarcinoma patients. However, targetable driver mutations are mainly found in thyroid transcription factor‐1 (TTF‐1)/NK2 homeobox 1 (NKX2‐1)‐positive terminal respiratory unit (TRU) types and rarely in non‐TRU types. To elucidate the molecular characteristics of the major subtypes of non‐TRU‐type adenocarcinomas, we analyzed 19 lung adenocarcinoma cell lines (11 TRU types and 8 non‐TRU types). A characteristic of non‐TRU‐type cell lines was the strong expression of TFF‐1 (trefoil factor‐1), a gastric mucosal protective factor. An immunohistochemical analysis of 238 primary lung adenocarcinomas resected at Jichi Medical University Hospital revealed that TFF‐1 was positive in 31 cases (13%). Expression of TFF‐1 was frequently detected in invasive mucinous (14/15, 93%), enteric (2/2, 100%), and colloid (1/1, 100%) adenocarcinomas, less frequent in acinar (5/24, 21%), papillary (7/120, 6%), and solid (2/43, 5%) adenocarcinomas, and negative in micropapillary (0/1, 0%), lepidic (0/23, 0%), and microinvasive adenocarcinomas or adenocarcinoma in situ (0/9, 0%). Expression of TFF‐1 correlated with the expression of HNF4‐α and MUC5AC (P < .0001, P < .0001, respectively) and inversely correlated with that of TTF‐1/NKX2‐1 (P < .0001). These results indicate that TFF‐1 is characteristically expressed in non‐TRU‐type adenocarcinomas with gastrointestinal features. The TFF‐1‐positive cases harbored KRAS mutations at a high frequency, but no EGFR or ALK mutations. Expression of TFF‐1 correlated with tumor spread through air spaces, and a poor prognosis in advanced stages. Moreover, the knockdown of TFF‐1 inhibited cell proliferation and soft‐agar colony formation and induced apoptosis in a TFF‐1‐high and KRAS‐mutated lung adenocarcinoma cell line. These results indicate that TFF‐1 is not only a biomarker, but also a potential molecular target for non‐TRU‐type lung adenocarcinomas.

Invasive mucinous adenocarcinoma of the lung

Invasive mucinous adenocarcinoma (IMA) is a unique histological subtype of adenocarcinoma. Due to its low incidence rates, survival data for IMA is scarce and often contradictory. The clinical manifestations of IMA are not precise as compared to other adenocarcinomas, with some patients having bronchial mucus overflow. Difference in immunohistochemical expression levels is present in IMA and invasive non-mucinous adenocarcinomas (INMA). Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are more frequent in IMAs, while epidermal growth factor receptor (EGFR) mutations are relatively rare. This makes it distinct from the other more common adenocarcinomas. Neuregulin 1 (NRG1) gene fusions are considered important therapeutic targets for IMA, suggesting that Afatinib may be an effective drug to treat IMA. However, IMA prognosis remains controversial.

Requirement for MUC5AC in KRAS-dependent lung carcinogenesis

With more than 150,000 deaths per year in the US alone, lung cancer has the highest number of deaths for any cancer. These poor outcomes reflect a lack of treatment for the most common form of lung cancer, non-small cell lung carcinoma (NSCLC). Lung adenocarcinoma (ADC) is the most prevalent subtype of NSCLC, with the main oncogenic drivers being KRAS and epidermal growth factor receptor (EGFR). Whereas EGFR blockade has led to some success in lung ADC, effective KRAS inhibition is lacking. KRAS-mutant ADCs are characterized by high levels of gel-forming mucin expression, with the highest mucin levels corresponding to worse prognoses. Despite these well-recognized associations, little is known about roles for individual gel-forming mucins in ADC development causatively. We hypothesized that MUC5AC/Muc5ac, a mucin gene known to be commonly expressed in NSCLC, is crucial in KRAS/Kras-driven lung ADC. We found that MUC5AC was a significant determinant of poor prognosis, especially in patients with KRAS-mutant tumors. In addition, by using mice with lung ADC induced chemically with urethane or transgenically by mutant-Kras expression, we observed significantly reduced tumor development in animals lacking Muc5ac compared with controls. Collectively, these results provide strong support for MUC5AC as a potential therapeutic target for lung ADC, a disease with few effective treatments.

[Clinical Evaluation of A New Pathological Classification for Non-small Cell Lung Cancer Based on Histogenesis of Bronchial Tree]

背景与目的

近年来对肺癌研究的巨大发展，肺癌的病理学分类不断推陈出新。本研究旨在研究和验证非小细胞肺癌（non-small cell lung cancer, NSCLC）组织起源分子病理分类的临床价值和意义。

方法

通过免疫组织化学双染法对105例肺癌标本及正常肺组织进行P63/NapsinA、TTF-1/CK7标记，结合肿瘤免疫特征、组织学特点及正常肺组织的免疫特征，提出了NSCLC组织起源分子病理分类体系，将NSCLC分为支气管上皮癌、细支气管肺泡癌、肺泡细胞癌及分泌腺癌，并分析本分类与表皮生长因子受体（epidermal growth factor receptor, EGFR）突变及临床预后的关系。

结果

本分类体系下不同亚型NSCLC中EGFR突变及其类型具有相对特异性；生存分析表明该分类有助于NSCLC患者预后情况的判断。

结论

本研究提出的基于组织起源的NSCLC分类体系具有较好的临床实用价值。

Clinicopathological Characteristics and Mutations Driving Development of Early Lung Adenocarcinoma: Tumor Initiation and Progression

Lung cancer is the leading cause of cancer-related deaths worldwide, with lung adenocarcinoma representing the most common lung cancer subtype. Among all lung adenocarcinomas, the most prevalent subset develops via tumorigenesis and progression from atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to minimally invasive adenocarcinoma (MIA), to overt invasive adenocarcinoma with a lepidic pattern. This stepwise development is supported by the clinicopathological and molecular characteristics of these tumors. In the 2015 World Health Organization classification, AAH and AIS are both defined as preinvasive lesions, whereas MIA is identified as an early invasive adenocarcinoma that is not expected to recur if removed completely. Recent studies have examined the molecular features of lung adenocarcinoma tumorigenesis and progression. EGFR-mutated adenocarcinoma frequently develops via the multistep progression. Oncogene-induced senescence appears to decrease the frequency of the multistep progression in KRAS- or BRAF-mutated adenocarcinoma, whose tumor evolution may be associated with epigenetic alterations and kinase-inactive mutations. This review summarizes the current knowledge of tumorigenesis and tumor progression in early lung adenocarcinoma, with special focus on its clinicopathological characteristics and their associations with driver mutations (EGFR, KRAS, and BRAF) as well as on its molecular pathogenesis and progression.

GATA6-positive lung adenocarcinomas are associated with invasive mucinous adenocarcinoma morphology, hepatocyte nuclear factor 4α expression, and KRAS mutations

AIMS

GATA6 is known to play a role in lung development. However, its role in the carcinogenesis of lung cancer is not well studied. The aim of this study was to analyse GATA6 expression in lung adenocarcinomas (LAs) by immunohistochemistry (IHC) in order to define its association with clinicopathological characteristics.

METHODS AND RESULTS

IHC analysis of GATA6 was performed with tissue microarray slides containing 348 LAs. The association between GATA6 expression and clinicopathological parameters was evaluated. GATA6 expression in epithelial tumours other than lung cancer was also evaluated. GATA6 expression was found in 47 LAs (13.5%). This occurred more frequently in younger patients (P = 0.005), and was associated with the absence of lymph node metastasis (P =0.024), well-differentiated to moderately differentiated tumours (P < 0.001), the absence of lymphatic invasion (P = 0.020), and the absence of vascular invasion (P = 0.011). GATA6 expression was associated with mucin production (P < 0.001), the invasive mucinous adenocarcinoma subtype (P < 0.001), KRAS mutations (P = 0.026), expression of MUC2 (P < 0.001), CDX2 (P = 0.049), and MUC5AC (P < 0.001), and absence of expression of TTF-1 (P = 0.002). GATA6 expression was also associated with hepatocyte nuclear factor 4α (HNF4α) expression (P < 0.001). GATA6 expression tended to indicate better prognoses, whereas patients with HNF4α expression had significantly worse prognoses (P = 0.033). Of 270 tumours other than lung cancer, 110 expressed GATA6.

CONCLUSIONS

These findings suggest that GATA6 might interact with HNF4α and contribute to the development of mucinous-type LAs.

The more the micropapillary pattern in stage I lung adenocarcinoma, the worse the prognosis-a retrospective study on digitalized slides

Although the majority of lung adenocarcinomas show mixed pattern, only the predominant component is taken into account according to the novel classification. We evaluated the proportion of different patterns and their impact on overall survival (OS) and disease-free survival (DFS). Patterns were recorded according to predominance and their proportions were rated and calculated by objective area measuring on digitalized, annotated slides of resected stage I lung adenocarcinomas. Spearman's rank correlation, Kaplan-Meier models and the log rank test were used for statistical evaluation. Two hundred forty-three stage I adenocarcinoma were included. Lepidic pattern is more frequent in tumours without recurrence (20 vs. 8%), and lepidic predominant tumours have favourable prognosis (OS 90.5%, DFS 89.4%), but proportions above 25% are not associated with improving outcome. Solid and micropapillary patterns are more frequent in patients with recurrence (48 vs. 5% and 13 vs. 4%) and predominance of each one is associated with unfavourable prognosis (OS 64.1%, DFS 56.3% and OS 28.1%, DFS 28.1%, respectively). Above 25%, a growing proportion of solid or micropapillary pattern is not associated with worsening prognosis. In contrast, tumours having micropapillary pattern as secondly predominant form a different intermediate group (OS 51.1%, DFS 57.8%). Our study was based on measured area of each growth pattern on all available slides digitalized. This is the most precise way of determining the size of each component from the material available. We propose using predominant and secondly predominant patterns for prognostic purposes, particularly in tumours having solid or micropapillary patterns.

Biology of invasive mucinous adenocarcinoma of the lung

Invasive mucinous adenocarcinoma (IMA) is a unique histologic subtype of lung adenocarcinoma. Recent studies document distinctive genetic alterations (e.g., NRG1 fusions) and a "mucinous gene signature" in IMAs, as well as differences in clinical responses to traditional chemotherapies in IMAs versus non-mucinous adenocarcinomas. Our understanding of the genetic and clinical characteristics of IMAs has expanded, confirming the uniqueness of IMAs. Accordingly, IMAs require different therapeutic approaches than do lung adenocarcinomas in general. Here, we review recent updates on the genetic and clinical profiles of IMA of the lung.

Adipophilin expression in lung adenocarcinoma is associated with apocrine-like features and poor clinical prognosis: an immunohistochemical study of 328 cases

AIMS

The lipogenic pathway is up-regulated in proliferating cells. However, the clinical impact of neoplastic steatogenesis in lung cancer is unclear. The aim of the present study was to evaluate the association of intracytoplasmic lipids with the clinicopathological features of lung adenocarcinoma (ADC), by immunohistochemical analysis of adipophilin (ADP), a coating protein found on intracytoplasmic lipid droplets.

METHODS AND RESULTS

Tissue microarrays consisting of 328 primary lung ADCs surgically resected at Kyoto University Hospital were immunostained for ADP. Subsequently, correlations between ADP expression and clinical, molecular and survival data were performed. Fifty-one (15.5%) cases were ADP-positive. The presence of vascular invasion (P = 0.003), predominantly solid histology (P < 0.001), poorly differentiated type (P < 0.001), wild-type EGFR (P = 0.002), ALK fusion (P < 0.001), strong/diffuse mitochondrial staining (P < 0.001), a lack of surfactant protein B expression (P = 0.014) and a high Ki67 index (P < 0.001) were significantly correlated with ADP-positive ADC. In contrast, there were no correlations between ADP-positive ADC and sex, age, smoking history, tumour stage, thyroid transcription factor-1 expression, or KRAS mutational status. ADP-positive ADCs had apocrine-like features (P < 0.001). Patients with ADP-positive ADC had worse disease-free and overall survival (P = 0.047 and P = 0.013, respectively) than those with ADP-negative ADC.

CONCLUSIONS

ADP was expressed in a small proportion of lung ADCs. ADP-positive lung ADC was significantly associated with apocrine-like features, wild-type EGFR, and poor prognosis, suggesting that ADP-positive lung ADC could be a distinct subtype of lung adenocarcinoma, induced by up-regulation of the lipogenic pathway.

Discriminating between Terminal- and Non-Terminal Respiratory Unit-Type Lung Adenocarcinoma Based on MicroRNA Profiles

Lung adenocarcinomas can be classified into terminal respiratory unit (TRU) and non-TRU types. We previously reported that non-TRU-type adenocarcinoma has unique clinical and morphological features as compared to the TRU type. Here we investigated whether micro (mi)RNA expression profiles can be used to distinguish between these two subtypes of lung adenocarcinoma. The expression of 1205 human and 144 human viral miRNAs was analyzed in TRU- and non-TRU-type lung adenocarcinoma samples (n = 4 each) by microarray. Results were validated by quantitative real-time (qRT-)PCR and in situ hybridization. A comparison of miRNA profiles revealed 29 miRNAs that were differentially expressed between TRU- and non-TRU adenocarcinoma types. Specifically, hsa-miR-494 and ebv-miR-BART19 were up regulated by > 5-fold, whereas hsa-miR-551b was down regulated by > 5-fold in the non-TRU relative to the TRU type. The miRNA signature was confirmed by qRT-PCR analysis using an independent set of paired adenocarcinoma (non-TRU-type, n = 21 and TRU-type, n = 12) and normal tissue samples. Non-TRU samples showed increased expression of miR-494 (p = 0.033) and ebv-miR-BART19 (p = 0.001) as compared to TRU-type samples. Both miRNAs were weakly expressed in the TRU type but strongly expressed in the non-TRU type. Neither subtype showed miR-551b expression. TRU- and non-TRU-type adenocarcinomas have distinct miRNA expression profiles, suggesting that tumorigenesis in lung adenocarcinoma occur via different pathways.

Clinicopathological, Immunohistochemical, and Genetic Features of Primary Lung Adenocarcinoma Occurring in the Setting of Usual Interstitial Pneumonia Pattern

INTRODUCTION

An association between usual interstitial pneumonia (UIP) and carcinogenesis has been well established. However, few detailed analyses have investigated the clinicopathological, immunohistochemical, and genetic features of patients with primary lung adenocarcinoma (ADC) with UIP (UIP-ADC).

METHODS

We identified 44 patients with ADC in the setting of UIP (the UIP-ADC group) (1.9%) from 2309 patients with primary ADC and compared clinicopathological, immunohistochemical, and genetic features between the UIP-ADC group and patients with ADC without UIP (the non-UIP-ADC group).

RESULTS

Clinicopathological features of UIP-ADC included an older age at occurrence; male predominance; smoking history; predilection for the lower lobe; large tumor size; high incidence of lymph vessel invasion, pleural invasion, and lymph node metastasis; and poor survival rate. However, the cause of death of patients with UIP-ADC was largely influenced by respiratory complications. Histologically, patients in the UIP-ADC group could be stratified according to invasive mucinous-predominant subtype. Genetically, patients in the UIP-ADC group had lower EGFR and higher KRAS mutation rates compared with patients in the non-UIP-ADC group.

CONCLUSIONS

UIP-ADC was associated with a poor prognosis owing to the high frequency of perioperative complications rather than the malignancy of the tumor itself. There was a high prevalence of the invasive mucinous-predominant subtype in cases of UIP-ADC. UIP-ADC also had a low prevalence of EGFR mutations and a high prevalence of KRAS mutations. These findings suggest that UIP-ADC should be distinct from non-UIP-ADC.

UCHL1 provides diagnostic and antimetastatic strategies due to its deubiquitinating effect on HIF-1α

Hypoxia-inducible factor 1 (HIF-1) plays a role in tumour metastases; however, the genes that activate HIF-1 and subsequently promote metastases have yet to be identified. Here we show that Ubiquitin C-terminal hydrolase-L1 (UCHL1) abrogates the von Hippel-Lindau-mediated ubiquitination of HIF-1α, the regulatory subunit of HIF-1, and consequently promotes metastasis. The aberrant overexpression of UCHL1 facilitates distant tumour metastases in a HIF-1-dependent manner in murine models of pulmonary metastasis. Meanwhile, blockade of the UCHL1-HIF-1 axis suppresses the formation of metastatic tumours. The expression levels of UCHL1 correlate with those of HIF-1α and are strongly associated with the poor prognosis of breast and lung cancer patients. These results indicate that UCHL1 promotes metastases as a deubiquitinating enzyme for HIF-1α, which justifies exploiting it as a prognostic marker and therapeutic target of cancers.