Correlation between genetic alterations and histopathological subtypes in bronchiolo-alveolar carcinoma and atypical adenomatous hyperplasia of the lung

[Progress in Basic Research and Clinical Treatment of Multiple Pulmonary Nodules]

肺癌是世界上发病率和死亡率最高的肿瘤。随着多层螺旋计算机断层扫描（computed tomography, CT）技术的发展和肺癌筛查的广泛开展，越来越多的肺结节被发现, 其中不少是多发肺结节，这些结节在病理学上常被诊断为多原发肺腺癌。对于具有不同影像学特征的多发结节，首选处理方法不尽相同，且每个肺结节的处理方法仍存在很大争议。近年来多发肺结节各病灶的演进及病灶间的相互影响机制，病灶内和病灶间肿瘤细胞在基因组学方面的同质性和异质性也备受关注。本文从组织病理学、基因组学、外科处理等多方面综合论述多发肺结节的研究进展。

Concordant and Discordant EGFR Mutations in Patients With Multifocal Adenocarcinomas: Implications for EGFR-Targeted Therapy

PURPOSE

Adenocarcinoma remains the most common subtype of lung cancer in the United States. Most patients present with tumors that are invasive and often metastatic, but in some patients, multiple precursor in situ or minimally invasive adenocarcinoma tumors develop that can be synchronous and metachronous. These precursor lesions harbor the same spectrum of genetic mutations found in purely invasive adenocarcinomas, such as EGFR, KRAS, and p53 mutations. It is less clear, however, whether separate lesions in patients who present with multifocal disease share common underlying genetic driver mutations.

METHODS

Here we review the relevant literature on molecular driver alterations in adenocarcinoma precursor lesions. We then report 4 patients with multifocal EGFR mutant adenocarcinomas in whom we performed molecular testing on 2 separate lesions.

FINDINGS

In 2 of these patients, the mutations are concordant, and in 2 patients, the mutations are discordant. A review of the literature demonstrates increasing evidence that lesions with discordant mutations may confer a more favorable prognosis because they are unlikely to represent metastases.

IMPLICATIONS

Our findings suggest that the emergence of the dominant EGFR driver alteration is often independent between lesions in patients with multifocal adenocarcinomas, and thus the same targeted therapy may not be effective for all lesions. However, genetic testing of multiple lesions can help to distinguish separate primary tumors from metastatic disease.

Lung cancer in which the hypothesis of multi-step progression is confirmed by array-CGH results: A case report

The pathogenesis of lung cancer has not been fully elucidated and biological markers acting as predictors of tumor evolution and aggressiveness remain unidentified. The multi-step hypothesis, suggesting a progression from adenomatous hyperplasia (AAH) to adenocarcinoma (AC) through bronchioalveolar carcinoma (BAC), was highlighted in a previous cytogenetic study performed in a single case. The present study reports the results of an array-comparative genomic hybridization (a-CGH) analysis performed on the DNA obtained from the previously reported case that presented AAH, BAC and AC in one lung. The a-CGH results confirm and support the previous cytogenetic observations with new data, clearly supporting the hypothesis of a multi-step carcinogenic process in the lung.

Chronic lung injury by constitutive expression of activation-induced cytidine deaminase leads to focal mucous cell metaplasia and cancer

Activation-induced cytidine deaminase (AID) is an enzyme required for antibody diversification, and it causes DNA mutations and strand breaks. Constitutive AID expression in mice invariably caused lung lesions morphologically similar to human atypical adenomatous hyperplasia (AAH), which can be a precursor of bronchioloalveolar carcinoma. Similar to AAH, mouse AAH-like lesion (MALL) exhibited signs of alveolar differentiation, judging from the expression of alveolar type II (AT2) cell marker surfactant protein C (SP-C). However, electron microscopy indicated that MALL, which possessed certain features of a mucous cell, is distinct from an AAH or AT2 cell. Although MALL developed in all individuals within 30 weeks after birth, lung tumors occurred in only 10%; this suggests that the vast majority of MALLs fail to grow into visible tumors. MALL expressed several recently described markers of lung alveolar regeneration such as p63, keratin 5, keratin 14, leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5), and Lgr6. Increased cell death was observed in the lungs of AID transgenic mice compared with wild-type mice. Based on these observations, we speculate that MALL is a regenerating tissue compensating for cellular loss caused by AID cytotoxicity. AID expression in such regenerating tissue should predispose cells to malignant transformation via its mutagenic activity.

Lung cancer in never smokers

Lung cancer in never smokers (LCINS) has lately been recognized as a unique disease based on rapidly gained knowledge from genomic changes to treatment responses. The focus of this article is on current knowledge and challenges with regard to LCINS expanded from recent reviews highlighting five areas: (1) distribution of LCINS by temporal trends, geographic regions, and populations; (2) three well-recognized environmental risk factors; (3) other plausible environmental risk factors; (4) prior chronic lung diseases and infectious diseases as risk factors; and (5) lifestyles as risk or protective factors. This article will also bring attention to recently published literature in two pioneering areas: (1) histological characteristics, clinical features with emerging new effective therapies, and social and psychological stigma; and (2) searching for susceptibility genes using integrated genomic approaches.

Clinicopathologic analysis of multiple (five or more) atypical adenomatous hyperplasias (AAHs) of the lung: evidence for the AAH-adenocarcinoma sequence

OBJECTIVE

Clarification of the clinicopathologic characteristics of patients with multiple atypical adenomatous hyperplasias (AAHs).

MATERIALS AND METHODS

The subjects were 1,639 patients who underwent lobectomy or pneumonectomy for lung tumors. The clinicopathologic features of the AAHs in the lung background and the main tumors were examined with regard to the number and the size of the AAHs, the incidence and histology of adenocarcinomas (ADs), and the outcome.

RESULTS

Thirty-two patients (2.0%) had 5 or more AAHs (ranging from 5 to 171), being present predominantly in the upper lobe (86%) and in women (75%). Among the 794 AAHs, 495 (62%) measured less than 1 mm, 170 (22%) measured 1 to less than 2 mm, 118 (15%) measured 2 to less than 5 mm, and 11 (1%) measured 5 to less than 10 mm. Twenty-eight patients (88%) had AD (1 in 18 patients and 2 to 6 in 10 patients). Thirty-two of the 51 patients with ADs (63%) had an AAH component. The incidence of ADs among the total of both AAHs and ADs was 6.0% (51 of 845). The 5-year cancer-free survival rate was 71.4%.

CONCLUSION

Five or more AAHs were seen in the background in 2.0% of lung tumors. Most of the AAHs were small, measuring less than 2 mm, and few exceeded 5 mm. Most of the patients had ADs, which were histologically suggested to be derived from AAH. However, the incidence of the AAH-AD sequence was considered to be low at the tumor basis, and the outcome of ADs was not very favorable.

Characterization of adenocarcinoma of the lung in a familial adenomatous polyposis patient

The incidence of several extracolonic tumors, such as duodenal carcinoma, is higher in familial adenomatous polyposis (FAP) patients than in the general population, but there is little information about lung carcinoma in FAP. A 43-year-old woman presented with a lung tumor 17 years after total colectomy for FAP. Pathohistological analysis of the lung tumor demonstrated mixed adenocarcinoma consisting of a papillary adenocarcinoma component and a bronchioloalveolar carcinoma component. Sequencing analysis indicated a germline APC mutation from TCA to TGA (stop) at codon 1110, but no pathogenic germline MYH mutations. The other APC allele in the lung carcinoma was not inactivated by somatic mutations, promoter methylation, or chromosomal deletion. No somatic mutations in any of the coding regions of the p53 gene or in the mutation hot spot regions of the K-ras or EGFR genes were detected in the carcinoma. Amplification, however, of three chromosome regions, 5p, 8q, and 12q14-12q21, was identified in the carcinoma on genome-wide high-resolution single-nucleotide polymorphism (SNP) microarray. The present results suggest that the chromosomal copy number alterations detected on SNP microarray were involved in the carcinogenesis of the adenocarcinoma of the lung in the present FAP patient.

Loss and reduction of FUS1 protein expression is a frequent phenomenon in the pathogenesis of lung cancer

PURPOSE

FUS1, a novel tumor-suppressor gene located in the chromosome 3p21.3 region, may play an important role in lung cancer development. Currently, FUS1-expressing nanoparticles have been developed for treating patients with lung cancer. However, the expression of Fus1 protein has not been examined in a large series of lung cancers and their sequential preneoplastic lesions.

EXPERIMENTAL DESIGN

Using tissue microarrays, we examined Fus1 immunohistochemical expression in 281 non-small cell lung carcinoma (NSCLC) and 22 small cell lung carcinoma tissue specimens and correlated the findings with patients' clinicopathologic features. To investigate the expression of Fus1 in the early sequential pathogenesis of NSCLC, we studied Fus1 expression in 211 histologically normal and mildly abnormal bronchial epithelia, and 118 bronchial and alveolar preneoplastic lesions obtained from patients with lung cancer.

RESULTS

Loss and reduction of expression was detected in 82% of NSCLCs and 100% of small cell lung carcinomas. In NSCLCs, loss of Fus1 immunohistochemical expression was associated with significantly worse overall survival. Bronchial squamous metaplastic and dysplastic lesions expressed significantly lower levels of Fus1 compared with normal (P = 0.014 and 0.047, respectively) and hyperplastic (P = 0.013 and 0.028, respectively) epithelia.

CONCLUSIONS

Our findings show a high frequency of Fus1 protein loss and reduction of expression in lung cancer, and suggests that this reduction may play an important role in the early pathogenesis of lung squamous cell carcinoma. These findings support the concept that FUS1 gene and Fus1 protein abnormalities could be used to develop new strategies for molecular cancer therapy for a significant subset of lung tumors.

Microsatellite and EGFR, HER2 and K-RAS analyses in sclerosing hemangioma of the lung

Sclerosing hemangioma (SH) is an uncommon pulmonary tumor thought to derive from primitive respiratory epithelium consisting of 2 cell populations (cuboidal surface and polygonal stromal cells) and sharing some clinical characteristics (frequent occurrence in nonsmoking women of Asian ethnicity) with bronchioloalveolar carcinoma with which it has been suggested a possible common origin. We investigated 11 cases of SH by immunohistochemistry, fluorescence in situ hybridization, and polymerase chain reaction-based microsatellite and mutational analyses with particular emphasis on possible alterations of microsatellite loci located at tumor suppressor genes (FHIT, p16, Rb, and p53) involved in lung adenocarcinoma genesis and EGFR, HER2, and K-RAS genes. Although EGFR expression was observed in all tested cases, none showed HER2 immunostaining. Fluorescence in situ hybridization and mutational analysis of EGFR and HER2 and also K-RAS sequencing did not reveal molecular alterations, whereas allelic losses at p16 and Rb loci (4 and 2 out of 9 tested cases, respectively) with an identical microsatellite allelic loss pattern in both cuboidal and polygonal cells were observed. The finding of microsatellite alterations in chromosomal regions related to genes deeply involved in early stage lung adenocarcinoma could suggest a possible link between SH and bronchioloalveolar carcinoma, but tumor pathway promoted by EGFR, HER2, and K-RAS does not represent a common molecular mechanism of tumorigenesis. Microsatellite alterations identified in cuboidal and polygonal cells further confirm the clonal and neoplastic nature of both components of SH.

Mucinous Cells in Type 1 Pulmonary Congenital Cystic Adenomatoid Malformation as Mucinous Bronchioloalveolar Carcinoma Precursors

Type 1 congenital cystic adenomatoid malformation (CCAM), the most frequent malformation of the lung, is the only type to present intracystic mucinous cell clusters, which may form beyond the cysts extracystic mucinous proliferation resembling mucinous bronchioloalveolar carcinomas (BACs). As mucinous BACs are increasingly described in the literature in young patients with CCAM, we hypothesized that type 1 CCAM mucinous cells could represent BAC precursors. We reviewed 7 cases of type 1 CCAM including 6 with intracystic mucinous cell clusters, 3 with extracystic mucinous proliferations, and 4 with mucinous BAC or mixed adenocarcinoma with predominant BAC. K-ras mutations at codon 12 were detected in 3/3 intracystic mucinous cell clusters, in 2/3 extracystic mucinous proliferations, and in 3/4 BAC. Loss of heterozygosity (LOH) at p16(INK4) locus, with microsatellite alterations in 3 cases, was observed in 2/3 intracystic mucinous cell clusters, in 2/3 extracystic mucinous proliferations, and in all BAC. Two extracystic mucinous proliferations showed LOH at FHIT and Rb loci, respectively. P16(INK4) expression was lost in 2 intracystic mucinous cell clusters, 1 extracystic mucinous proliferation, and 1 BAC. Neither epidermal growth factor receptor mutation on exons 18, 19, and 21 nor P53 accumulation was observed. All lesions expressed MUC5AC, but were negative for MUC2, CDX2, and TTF-1. In conclusion, type 1 CCAM mucinous cells share the same differentiation profile with corresponding mucinous BAC, consistent with a common bronchial origin. Moreover, the high frequency of K-ras mutation and LOH and/or microsatellite alterations at p16(INK4) locus presented by these mucinous cells justifies their consideration as BAC precursors.

Molecular Alterations in Atypical Adenomatous Hyperplasia Occurring in Benign and Cancer-bearing Lungs

Atypical adenomatous hyperplasia (AAH) is considered to be a precursor lesion of the lung adenocarcinoma. Several genetic abnormalities have been reported in AAH associated with adenocarcinoma, but little is known about AAH associated with benign lung lesions. To address this we compared the molecular characteristics of AAH present in benign conditions to those coexisting with carcinoma. Seven cases of AAH from resected non-neoplastic lungs (AAH-B) and 12 cases from lungs resected for primary lung carcinoma (AAH-M) were analyzed for loss of heterozygosity (LOH) using 21 polymorphic microsatellite markers situated in proximity to known tumor suppressor genes on chromosomes 3p, 5q, 7p, 9p, 10q, and 17p. Direct DNA sequencing for K-ras mutation was also performed. There was a broad range of LOH in both groups. No LOH was identified in 3 cases (25%) of AAH-M, but all cases of AAH-B showed LOH (P=0.26). Six cases (50%) of AAH-M and 3 cases (43%) of AAH-B showed loss at 1 marker (P=0.99). LOH at 2 or more markers was identified in 3 (25%) cases of AAH-M and 4 (57%) cases of AAH-B (P=0.32). LOH was most frequently detected on chromosomes 3p and 10q in both groups. The difference in overall fractional allelic loss between the 2 groups did not reach statistical significance. K-ras mutations were not identified in either group. Our results showed a significant overlap in LOH patterns between AAH with or without coexistent lung malignancy. Therefore, AAH may represent a smoking induced low-grade neoplastic lesion that may be a precursor lesion of only a subset of invasive lung adenocarcinoma.

Genetic relationship among atypical adenomatous hyperplasia, bronchioloalveolar carcinoma and adenocarcinoma of the lung

Atypical adenomatous hyperplasia (AAH) has been recently defined by WHO as a small lesion, not exceeding 5mm in major axis, composed of slightly enlarged alveolar septa lined by pneumocytes with plump, atypical nuclei. AAH is frequently found in tissue surrounding lung adenocarcinoma and is considered a precursor of this subtype of lung cancer by many Authors. However, the genetic relationship between adenocarcinoma and the associated foci of AAH is not well defined. In particular, it is not clear whether multiple foci of AAH and of adenocarcinoma in the same patients are clonally related to each other or represent independent neoplastic foci. To clarify if AAH and the associated cancer are clonally related, we evaluated the genetic distance between these two lesions in 16 patients, using direct sequencing of mitochondrial DNA (D-loop region). Furthermore, LOH analysis for 7 microsatellites (D3S1478 at 3p21, D3S1300 at 3p14.2, D9S942 at 9p21, D5S346 at 5q21, D17S261 at 17p13.1, D18S46 at 18q21, D19S246 at 19q13.2) was also performed. Our results indicate that, in at least 9 out of 13 informative cases (69.2%), AAH and the associated cancer were not clonally related as they showed a different mutation pattern in the mitochondrial D-loop region. These findings were also in agreement with the LOH data which showed losses in different loci in at least three cases. On the contrary an identical LOH pattern between BAC and AAH was found in one case. Similar but not identical LOH pattern between AAH and related tumors was found in other three cases. Therefore, our results suggest that AAH and the associated cancer are genetically independent in agreement with the concept of cancerization field. Less frequently AAH foci could represent an early spread of cells from the main tumor, rather than a precursor lesion.

Bronchioloalveolar carcinoma of mixed mucinous and nonmucinous type: Immunohistochemical studies and mutation analysis of the p53 gene

Bronchioloalveolar carcinoma of mixed mucinous and nonmucinous type fulfilling the 1999 WHO criteria is rare. Here, we report a case of this type of tumor determined entirely by histological examinations. A 57-year-old man was incidentally found to have a demarcated 3cm mass in his lower lobe of the right lung. The tumor was composed of tall columnar cells containing cytoplasmic mucins, cuboidal cells without mucins, and intermediate cell types with lepidic growth patterns. Tumor cells were distributed within a region of 2cm in diameter, and no stromal, vascular, or pleural invasion was observed. Immunohistochemically, both the mucinous and nonmucinous components were positive for cytokeratin 7, TTF-1, and E-cadherin, and negative for cytokeratin 20, consistent with the results for nonmucinous bronchioloalveolar carcinoma. No mutations were detected in exons 5-8 of the p53 gene. The present tumor was composed mainly of morphologically mucinous bronchioloalveolar carcinoma, but presented different immunohistochemical profiles of ordinary mucinous bronchioloalveolar carcinoma. This case suggests that the mucinous component in bronchioloalveolar carcinoma of mixed mucinous and nonmucinous type has characters dissimilar to conventional mucinous bronchioloalveolar carcinoma, and is probably derived from the nonmucinous component.

Bronchioloalveolar carcinoma: a review

Bronchioloalveolar carcinoma (BAC) is classified as a subset of lung adenocarcinoma but has a distinct clinical presentation, tumor biology, response to therapy, and prognosis compared with other subtypes of non-small-cell lung carcinoma (NSCLC). Bronchioloalveolar carcinoma disproportionately affects women, never-smokers, and Asians and is characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion. Although pure BAC accounts for approximately 4% of lung cancers, tumors with histologically mixed BAC and adenocarcinoma account for > 20% of all NSCLCs, and the incidence of BAC might be increasing. Bronchioloalveolar carcinoma histology is most commonly found in small lesions identified incidentally on chest radiographs or computed tomography scans and might represent a precursor lesion to invasive adenocarcinoma. As with other subsets of NSCLC, surgical resection is the only potentially curative treatment. Patients with unresectable BAC are more likely to respond to the epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib than patients with other subtypes of NSCLC. Stage for stage, patients with BAC have a higher rate of long-term survival but might have an increased rate of intrathoracic recurrence than patients with other subtypes of NSCLC.

Grg1 acts as a lung-specific oncogene in a transgenic mouse model

Groucho proteins are transcriptional corepressors that are recruited to gene regulatory regions by numerous transcription factors. Long isoforms, such as Grg1, have all the domains of the prototype Drosophila Groucho. Short Groucho proteins, such as Grg5, have only the amino-terminal Q and G/P domains. We generated Grg1 and Grg5 transgenic mice and found that Grg1 overexpression induces lung adenocarcinoma, whereas Grg5 overexpression does not. Coexpression of Grg5 with Grg1 reduces tumor burden. Grg1 and Grg5 both diminish p53 protein levels; however, only Grg1 overexpression induces elevated levels of ErbB1 and ErbB2 receptor tyrosine kinases. The molecular and biological changes that accompany tumor progression in Grg1 transgenic mice closely reiterate events seen in human lung cancer. We also found that within a human lung tumor tissue array, a significant number of carcinomas overexpress Grg1/TLE1. Our data suggest that Grg1 overexpression contributes to malignancy in human lung cancers.

Aberrant methylation and loss of expression of O-methylguanine-DNA methyltransferase in pulmonary squamous cell carcinoma and adenocarcinoma

O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that protects cells against the carcinogenic effects of alkylating agents. The methylation status of the MGMT gene was investigated by methylation-specific polymerase chain reaction (PCR) and expression status was investigated by immunohistochemistry in 70 cases of pulmonary squamous cell carcinoma (pulmonary SqCC), including 23 cases of the central type and 47 cases of the peripheral type, and in 53 cases of the peripheral type of pulmonary adenocarcinoma (AC). The frequency of MGMT methylation was 36% in SqCC and 42% in AC. Cases with MGMT methylation correlated significantly with T factor in SqCC (P = 0.047) and AC (P = 0.03). In SqCC, the frequency of MGMT methylation was 26% in the central type and 40% in the peripheral type; a significant correlation was not found (P = 0.29). In AC with mixed subtypes showing MGMT methylation, the level of MGMT expression in the bronchioloalveolar carcinoma (BAC) area (non-invasive status) was significantly higher than that in the papillary or acinar AC area (invasive status; P = 0.0002). This trend was not found in AC with mixed subtypes showing no MGMT methylation (P = 0.10). These findings suggest that MGMT inactivation is an event that occurs in the late carcinogenic process in SqCC and AC, and that AC progress from non-invasive status to invasive status with MGMT inactivation induced by the promoter DNA methylation.

Inhibition of mammalian target of rapamycin reverses alveolar epithelial neoplasia induced by oncogenic K-ras

The serine/threonine kinase AKT and its downstream mediator mammalian target of rapamycin (mTOR) are activated in lung adenocarcinoma, and clinical trials are under way to test whether inhibition of mTOR is useful in treating lung cancer. Here, we report that mTOR inhibition blocked malignant progression in K-ras(LA1) mice, which undergo somatic activation of the K-ras oncogene and display morphologic changes in alveolar epithelial cells that recapitulate those of precursors of human lung adenocarcinoma. Levels of phospho-S6(Ser236/235), a downstream mediator of mTOR, increased with malignant progression (normal alveolar epithelial cells to adenocarcinoma) in K-ras(LA1) mice and in patients with lung adenocarcinoma. Atypical alveolar hyperplasia, an early neoplastic change, was prominently associated with macrophages and expressed high levels of phospho-S6(Ser236/235). mTOR inhibition in K-ras(LA1) mice by treatment with the rapamycin analogue CCI-779 reduced the size and number of early epithelial neoplastic lesions (atypical alveolar hyperplasia and adenomas) and induced apoptosis of intraepithelial macrophages. LKR-13, a lung adenocarcinoma cell line derived from K-ras(LA1) mice, was resistant to treatment with CCI-779 in vitro. However, LKR-13 cells grown as syngeneic tumors recruited macrophages, and those tumors regressed in response to treatment with CCI-779. Lastly, conditioned medium from primary cultures of alveolar macrophages stimulated the proliferation of LKR-13 cells. These findings provide evidence that the expansion of lung adenocarcinoma precursors induced by oncogenic K-ras requires mTOR-dependent signaling and that host factors derived from macrophages play a critical role in adenocarcinoma progression.

Clonal selection of adenocarcinoma of the lung as determined by loss of heterozygosity

Although the most frequently altered oncogenes and tumor suppressor genes in non-small cell lung carcinoma (NSCLC) have been recognized, the exact mechanisms responsible for the progression and phenotypic expression of carcinoma, particularly adenocarcinoma of the lung are uncertain. Fifty-six cases of adenocarcinoma of the lung (11 bronchioloalveolar carcinoma [BAC], 25 stage 1, 20 stage 2) and paired 19 lymph node metastases (LNM) of stage 2 adenocarcinomas were analyzed for loss of heterozygosity (LOH). Analysis included a panel of 14 polymorphic microsatellite markers located on 1p, 3p, 5q, 9p, 10q, and 17p. LOH on chromosomes 1p (P = 0.0209) and 17p (P = 0.0274) was more frequently present in stage 1 adenocarcinomas than in BAC. There was no significant difference between BAC, stage 1 and stage 2 adenocarcinoma in the frequency of LOH at individual chromosomal arms. The pattern of LOH in LNM of stage 2 adenocarcinoma was similar to the primary tumor. Overall fractional allelic loss (FAL) was significantly different between BAC and stage 1 invasive adenocarcinoma (P = 0.0013), and it was significantly higher in stage 1 adenocarcinoma than in stage 2 adenocarcinoma (P = 0.0062) and their LNM (P = 0.0001). Stage 2 adenocarcinomas showed significantly higher overall FAL than their LNM (P = 0.022). Our study failed to identify a single target gene responsible for progression of lung adenocarcinoma. A trend towards lower overall FAL in advanced stage tumors and in their metastases suggests that clonal selection may play a role in lung adenocarcinoma progression.

Loss of expression of E-cadherin and beta-catenin is associated with progression of pulmonary adenocarcinoma

The aim of the present study was to determine the association of loss of membranous expression of epithelial (E)-cadherin and beta-catenin with the progression of pulmonary adenocarcinoma. The expression of E-cadherin and beta-catenin was examined in 154 cases of pulmonary adenocarcinoma, including 49 cases of atypical adenomatous hyperplasia (AAH), 40 cases of bronchioloalveolar carcinoma (BAC), 42 cases of BAC-dominant type of adenocarcinoma with mixed subtypes (early MX) and 23 cases of BAC-recessive type of adenocarcinoma with mixed subtypes (overt MX), by immunohistochemistry. E-cadherin expression was positive in all cases of AAH, in 37 cases (92.5%) of BAC and in 34 cases (81.0%) of early MX, while it was positive in three cases (13.0%) of overt MX. beta-Catenin expression was positive in 47 cases (95.9%) of AAH, in 28 cases (70%) of BAC, in 32 cases (76.2%) of early MX and in 11 cases (47.8%) of overt MX. The rates of expression of E-cadherin and beta-catenin among cases of AAH, BAC, early MX and overt MX were significantly reduced. Loss of expression of E-cadherin and beta-catenin may play an important role in the progression of pulmonary adenocarcinoma, and these events occur before structural destruction of the alveolar wall by invasion of carcinoma cell.

Genetic Profile of Cumulative Mutational Damage Associated With Early Pulmonary Adenocarcinoma

To detect the possible genetic alterations characteristic of bronchioloalveolar carcinoma (BAC) and to study molecular genetic factors responsible for determining the biologic aggressiveness of pulmonary adenocarcinoma, comparative analysis of loss of heterozygosity (LOH) on 9 chromosomal regions was performed in 14 BACs and in 20 stage I adenocarcinomas (AD). The most frequently affected chromosome regions in BAC were 8q and 17p. In stage I AD, more than 60% of the cases showed LOH of 1p, 3p, 5q, 7q, 17p, and 18q loci, and LOH of 1p, 3p, 7q, and 18q was observed with greater frequency than in BAC (P < 0.05). Fractional allele loss (FAL) was significantly greater in stage I AD than in BAC (P < 0.001). In cases with microdissection of multiple sites, intratumoral heterogeneity of LOH status was observed in 73% of BAC and 94% of stage I AD, and homogeneous distribution of LOH of 9p was unique to BAC. The high FAL value was associated with a poor prognosis of BAC, but this trend did not reach statistical significance (P = 0.098). In stage I AD, no correlation was found between LOH of particular chromosomal region or FAL and clinical outcome. LOH of 1p, 3p, 7q, and 18q was associated with invasive properties of pulmonary AD and may be useful in identifying invasive adenocarcinoma when conventional histomorphological tools are not helpful.

Bronchiolar columnar cell dysplasia--genetic analysis of a novel preneoplastic lesion of peripheral lung

Atypical adenomatous hyperplasia is the only known precursor lesion of lung adenocarcinomas (ACs) so far. Here, we describe a new dysplastic lesion in the bronchioles of peripheral lung for which we propose the name bronchiolar columnar cell dysplasia (BCCD). Eight of fourteen BCCDs were successfully analyzed by means of comparative genomic hybridization (CGH). The average number of chromosomal aberrations was 2.6 in BCCD and 14.7 in concomitant AC. Among the aberrations were losses of 3p, 9, 13, 14 and gains of 1q, 17, 19q and 20q. Summarizing our data from morphological and genetic analysis, we conclude that BCCD is a preneoplasia of the bronchiolar epithelium and most probably represents an additional precursor lesion of lung adenocarcinomas.

Is high-grade adenomatous hyperplasia an early bronchioloalveolar adenocarcinoma?

Atypical adenomatous hyperplasia (AAH) is a probable forerunner of bronchioloalveolar carcinoma (BAC) and pulmonary adenocarcinoma (AC) of mixed type. The present study analysed four low-grade AAHs, 13 high-grade AAHs, two BACs, nine mixed ACs, and one squamous cell carcinoma derived from 13 patients using comparative genomic hybridization. The average number of chromosomal aberrations was 1.2 in low-grade AAH, 9.6 in high-grade AAH, and 12.5 in AC. A high degree of overlap of genetic changes was found in high-grade AAH, BAC, and AC within individual patients. The high number of aberrations and the degree of shared aberrations found in high-grade AAH and AC raises questions about the separation of these two entities. In addition, in view of the monoclonal origin of multiple foci within the same patient, AAH may not be a precursor of AC in some cases, but rather may represent intraepithelial spread.

Preneoplastic lesions of the lung

Lung cancer is the leading cause of cancer deaths worldwide. If we can define and detect preneoplastic lesions, we might have a chance of improving survival. The World Health Organization has defined three preneoplastic lesions of the bronchial epithelium: squamous dysplasia/carcinoma in situ; atypical adenomatous hyperplasia; and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. These lesions are believed to progress to squamous cell carcinoma, adenocarcinoma and carcinoid tumors, respectively. In this review we summarize the data supporting the preneoplastic nature of these lesions, and delve into some of the genetic changes found in atypical adenomatous hyperplasia and squamous dysplasia/carcinoma in situ.