Pathology of lung cancer

Bronchial epithelial Ki-67 index is related to histology, smoking, and gender, but not lung cancer or chronic obstructive pulmonary disease

PURPOSE

To determine whether increased bronchial epithelial proliferation is associated with histology, smoking status, gender, age, chronic obstructive pulmonary disease (COPD), or lung cancer.

EXPERIMENTAL DESIGN

Cross-sectional study of 113 subjects undergoing white light and autofluorescence bronchoscopy: 27 never smokers; 27 current or ex-smokers with normal spirometry; 31 current or ex-smokers with COPD; and 28 current, ex-, or never smokers with lung cancer. Ki-67 expression was determined by immunohistochemistry on all evaluable biopsy sites without carcinoma. Relationships between Ki-67 index (percentage of epithelial cells expressing Ki-67), demographic variables, smoking, histology, and the presence of COPD and/or lung cancer were determined.

RESULTS

Results for both maximal and mean Ki-67 index are similar, so only the former are reported. Average maximal Ki-67 index was higher in current smokers than either ex-smokers or never smokers (48.0% versus 30.6% versus 22.6%; P<0.001). Males had higher Ki-67 index than females (39.9% versus 23.6%; P<0.001). Compared with subjects without disease (Ki-67 index=30.0%), maximal Ki-67 index was not significantly elevated (P=0.44) in subjects with either lung cancer (Ki-67=39.1%) or COPD (Ki-67=38.9%).

CONCLUSIONS

Smoking status, bronchial histology, and gender were significantly associated with Ki-67 index. No increase in Ki-67 index was found in the nonmalignant epithelium of patients with lung cancer or COPD. Although Ki-67 index may provide insight into the short-term effects of chemoprevention agents on cell proliferation, its lack of association with lung cancer or COPD raises question regarding its utility as a lung cancer risk biomarker.

Amelioration of benzo (a) pyrene-induced lung carcinogenesis in strain A mice by diphenylmethyl selenocyanate

Organoselenocyanates are an important class of chemopreventive agents, which possess antioxidative, antimutagenic and anticarcinogenic properties. In the present study, we used benzo (a) pyrene (BP)-induced lung carcinogenesis model for assessment of the chemopreventive efficacy of diphenylmethyl selenocyanate, a synthetic organoselenocyanate. BP was given at a dose of 0.2mg/mouse to initiate lung carcinogenesis in strain A mouse and the Se compound was given orally at a dose of 3mg/kgb.w. Histopathological characterizations and biochemical estimation were done to determine the protective effect of Se compound during the progression of lung carcinogenesis. Hyperplasia and severe dysplasia, the precancerous stage, were evident in carcinogen control group after 8th and 22nd week, respectively. These times were selected as the targets for chemoprevention. Treatment with the Se compound effectively reduced the incidence of hyperplasia and severe dysplasia. The Se compound also significantly (p<0.01) reduced microsomal lipid peroxidation and induced glutathione-S-transferase activity in liver and lung when measured after 8th and 22nd week. Lung cancer is diagnosed in majority of cases only at a later stage. These findings will further strengthen the view on organoselenocyanate as an effective cancer chemopreventive agent against lung carcinogenesis when applied at the post-initiation phase.

The diffuse endocrine system: from embryogenesis to carcinogenesis

In the present review we will summarise the current knowledge about the cells comprising the Diffuse Endocrine System (DES) in mammalian organs. We will describe the morphological, histochemical and functional traits of these cells in three major systems gastrointestinal, respiratory and prostatic. We will also focus on some aspects of their ontogeny and differentiation, as well as to their relevance in carcinogenesis, especially in neuroendocrine tumors. The first chapter describes the characteristics of DES cells and some of their specific biological and biochemical traits. The second chapter deals with DES in the gastrointestinal organs, with special reference to the new data on the differentiation mechanisms that leads to the appearance of endocrine cells from an undifferentiated stem cell. The third chapter is devoted to DES of the respiratory system and some aspects of its biological role, both, during development and adulthood. Neuroendocrine hyperplasia and neuroendocrine lung tumors are also addressed. Finally, the last chapter deals with the prostatic DES, discussing its probable functional role and its relevance in hormone-resistant prostatic carcinomas.

Morphological aspects of carcinogenesis in the lung

The origins of the various histological types of primary lung cancer are not well understood. Numerous recent studies have indicated that lung cancer is not a result of a sudden transforming event in the bronchial and alveolar epithelium and in the neuroendocrine cells, but a multistep process in which a sequence of morphological and genetic changes is occurring. New modern technical approaches like fluorescence bronchoscopy techniques and microdissection, provide facilities to obtain valuable specimens for morphological and genetic verification of the sequentional changes in lung cancerogenesis. With their help, cells with morphologically recognized changes thought to be preneoplastic, may be removed and prepared for molecular and genetic studies. Therefore, the knowledge of the morphological aspects of lung preneoplastic lesions is crucial to make progress in molecular studies of lung carcinogenesis. Presently the knowledge about the sequence of molecular events in the lung carcinogenesis and their relationship to morphology is not perfect. In this review we will describe morphological aspects of various preneoplastic lesions occurring in the bronchial and bronchiolo-alveolar compartments including neuroendocrine cells.

Human small cell lung carcinoma and carcinoid tumor regulate dendritic cell maturation and function

The induction of apoptosis in dendritic cells (DC) is a key mechanism by which tumors escape immune recognition and elimination. In fact, a number of studies have showed the correlation between the number of DC within the tumor and the clinical prognosis, suggesting that increased infiltration of tumor tissue by DC was associated with better patient survival and low incidence of metastatic disease. We compared the number of DC and their distribution pattern in human small-cell lung carcinoma and bronchial carcinoid tumor (CT) tissues. Immunohistochemical analysis revealed the presence of cells expressing DC markers CD1a and CD83 in small-cell lung carcinoma tissues and the complete absence of these cells in CT samples. Next, we examined whether human lung tumor cells produce soluble factors that inhibit differentiation of hematopoietic precursors into mature DC. The addition of small-cell lung carcinoma-conditioned medium to CD34+ precursor cell cultures significantly inhibited colony-forming units of DC formation when compared with nontreated control DC cultures. Furthermore, DC generation and differentiation was completely abrogated in CD34+ cell cultures treated with CT-conditioned medium, suggesting that CT-derived factors blocked CD34+ cell differentiation into DC or induced their apoptosis. Finally, flow cytometry analysis of cultured DC confirmed these results. Thus, analysis of our data suggests that human lung tumors produce factors that inhibit DC generation or maturation and may also induce apoptotic death of DC precursors in vitro.