The natural course of preneoplastic lesions in bronchial epithelium.

PURPOSE: To study the natural history of preneoplastic lesions in the bronchial mucosa of the individuals at risk. PATIENTS AND METHODS: White light and autofluorescence bronchoscopy examinations have been done in 52 individuals harboring 134 preneoplastic lesions (WHO criteria). End points were the development of carcinoma in situ (CIS) or squamous cell cancer (SCC) or the highest category of dysplasia up until March 1, 2003 for the remaining preneoplastic lesions. RESULTS: Distribution and outcome of preneoplastic lesions have been found to be unrelated to various risk factors such as smoking history, past history of cancer, or chronic obstructive pulmonary disease. Nonstepwise changes of preneoplastic lesions are seen. Regression rate has been 54%. Progression to CIS/SCC has been 13.4% (18 of 134) and was for severe dysplasia, significantly higher (P < 0.003) than preneoplastic lesions showing lower-grade dysplasia (squamous metaplasia, mild and moderate dysplasia). Time to progression was not significantly different. However, when analyzed per individual, no significant difference of progression rate between individuals with or without severe dysplasia was seen (39% versus 26%; P = 0.36). CONCLUSIONS: The 54% regression rate of all preneoplastic lesions, 26% to 39% progression rate to CIS/SCC of individuals with lower-grade dysplasia or severe dysplasia with no significant difference in progression rate and time to progression combined with nonstepwise histologic changes unrelated to the initial histologic grading indicate that one cannot differentiate the potentially more malignant preneoplastic lesions among the many preneoplastic lesions present in the bronchial mucosa. The initial WHO classification of any preneoplastic lesion cannot be reliably used for accurate risk assessment of field carcinogenesis.

Elevated hTERT mRNA levels: A potential determinant of bronchial squamous cell carcinoma (in situ).

Expression levels of hTERT mRNA were investigated by RT-PCR in tissue specimens of patients with (Group A) and without (Group B) clinically overt bronchial carcinoma, respectively. Bronchial carcinoma (n = 9) and distant normal (n = 9) specimens were analyzed in Group A. The chance of carcinoma seemed to increase with increasing hTERT mRNA levels (OR = 6.04, 95% CI = 1.02-37). Group B was comprised of 21 patients who underwent autofluorescence bronchoscopy. After analysis of 66 bronchial biopsies the chance of prevalent carcinoma in situ or carcinoma increased with increasing hTERT mRNA levels (OR = 6.19, 95% CI = 1.55-25). Variables like age, gender, smoking history, history of cancer within the airways or the degree of lymphocyte infiltrate in the specimens did not modify this relation. In 7 Group B patients in whom bronchial cancer was diagnosed during follow-up, biopsies taken before cancer diagnosis from both the area of the newly developed tumor and distantly from this area had been analyzed for hTERT expression. The median hTERT mRNA level in the biopsies from the area of future cancer was significantly higher than in biopsies taken from distant sites (p < 0.03). These data indicate that elevated hTERT mRNA is associated with an increased relative risk of prevalent and incident bronchial squamous cell carcinoma (in situ).

Increased expression of the EZH2 polycomb group gene in BMI-1-positive neoplastic cells during bronchial carcinogenesis.

Polycomb group (PcG) genes are responsible for maintenance of cellular identity and contribute to regulation of the cell cycle. Recent studies have identified several PcG genes as oncogenes, and a role for PcG proteins in human oncogenesis is suspected. We investigated the expression of BMI-1 and EZH2 PcG oncogenes in human bronchial squamous cell carcinomas (SCCs) and bronchial premalignant precursor lesions (PLs). Whereas normal bronchial epithelium was associated with widespread expression of BMI-1 in resting EZH2-negative cells, neoplastic cells in lung carcinomas displayed altered expression of both BMI-1 and EZH2. Two patterns of abnormal PcG expression were observed: increased expression of BMI-1 in dividing neoplastic cells of PLs and SCCs, and enhanced expression of EZH2 and Ki-67 in BMI-1-positive cells according to severity of the histopathologic stage. We propose that altered expression of BMI-1 and EZH2 is an early event that precedes high rates of proliferation in lung cancer. Because PcG complexes are normally involved in the maintenance of cell characteristics, abnormal PcG expression may contribute to loss of cell identity.

Suprabasal p53 immunostaining in premalignant endobronchial lesions in combination with histology is associated with bronchial cancer.

Endobronchial carcinoma develops through a continuum of morphologically recognizable pre-neoplastic changes. At present, no marker has been identified that can reliably predict the biological behavior of these lesions. Endobronchial lesions (n=39) sampled from patients (n=20) without clinically overt lung cancer, were analyzed by immunohistochemistry (IHC) for abnormal expression regarding the p53 protein, i.e. suprabasal p53 expression. Clear suprabasal p53 immunostaining was found in two (12%) of the hyperplastic or squamous metaplastic lesions, in one (10%) of the mildly or moderately dysplastic lesions and in nine (75%) of the severely dysplastic or carcinoma in situ (CIS) lesions. Suprabasal p53 immunostaining was found significantly more frequent in severe dysplasia or CIS (P<0.01). Of 17 patients follow-up data were available. After a median follow up of 7 months (range 2-37 months), six patients presented with bronchial carcinoma within the same lobe or bronchial spur where biopsies had been taken. Four of these patients revealed suprabasal p53 immunostaining in the biopsies obtained from the sites of future cancer. In three patients biopsies were obtained from future cancer sites as well as from distant sites in the ipsilateral lung. Suprabasal p53 immunostaining was found exclusively at future cancer sites of these patients (P=0.02). Suprabasal p53 immunostaining in addition to histology improved the specificity and the positive predictive value for bronchial carcinoma development in the same lobe or bronchial spur, compared with histology alone. These results suggest that suprabasal p53 immunostaining is associated with bronchial cancer and might have additive value to predict the biological behavior of pre-neoplastic endobronchial lesions in the population at risk of bronchial cancer.

Quantitative reverse transcription-polymerase chain reaction measurement of HASH1 (ASCL1), a marker for small cell lung carcinomas with neuroendocrine features.

PURPOSE: The Human Achaete-Scute homologue 1 (HASH1, ASCL1), a lineage-specific basic helix-loop-helix member of the achaete-scute family, is essential for the generation of pulmonary neuroendocrine (NE) cells during lung development. In small cell lung cancer (SCLC), the most lethal form of lung cancer, the gene is highly expressed and the expression of HASH1 correlates with NE features found in SCLCs. Here we describe a highly sensitive reverse transcription-PCR method for quantifying HASH1 mRNA in clinical samples, using real-time fluorescence resonance energy transfer technology (LightCycler). EXPERIMENTAL DESIGN: The HASH1-positive NE cell line NCI-H187 was compared with the non-NE cell line NCI-N417 by quantitative reverse transcription-PCR. Signals were normalized using the housekeeping gene PBGD, which is pseudogene free. Subsequently, HASH1 expression in RNA isolated from biopsies from SCLC patients (n = 4) was compared with biopsies from non-SCLC (NSCLC) patients (n = 2) or normal bronchus (n = 2). RESULTS: The HASH1-positive NE cell line NCI-H187 showed 50,000-fold higher normalized expression of HASH1 than did the non-NE cell line NCI-N417, indicating that the method is applicable over a wide dynamic range. Normalized average mRNA expression levels in SCLC clinical samples were 1,000-fold higher than in the NSCLC samples. Expression in normal bronchus was comparable to the expression levels in the NSCLC. CONCLUSIONS: These results show that marked and measurable differences exist between SCLCs and other lung tissues (either NSCLC or normal bronchus). We show that the method is applicable to small biopsy samples and can discriminate SCLC from NSCLC. This method could contribute to diagnosis based on molecular profiling of tumors.