p16 inactivation in small-sized lung adenocarcinoma: its association with poor prognosis.

p16, an inhibitor of cell cycle machinery, is frequently inactivated in non-small cell carcinoma of the lung (NSCCL). To clarify the significance of p16 inactivation in the progression of lung adenocarcinoma, we immunohistochemically evaluated p16 protein status and Rb, p53 and cyclin D1 expression in 51 surgically resected adenocarcinomas that were less than 3 cm in diameter (median follow-up period: 52.5 months). Twenty-one of 51 adenocarcinomas showed negative immunostaining for p16. Twenty adenocarcinomas were also negative for Rb, while 31 and 13 were positive for p53 and cyclin D1, respectively. Loss of p16 expression was significantly correlated with scar grade, lymphatic permeation, lymph node metastasis and clinical stage. Rb protein expression was also inversely correlated with scar grade, pleural involvement and vascular invasion. When the cases were stratified according to the expression of both proteins, the Rb-/p16- subset (7/51) consisted of poorly differentiated adenocarcinoma with a higher grade of invasion. While Rb, p53 and cyclin D1 protein status showed no significant correlations with prognosis, p16 inactivation was significantly correlated with poor prognosis, and the prognosis of Rb-/p16- was the worst among the 4 subsets. Inactivation of p16 may play a role in accelerating scar formation and lymph node metastasis, and may contribute through these mechanisms to poor prognosis in patients with small-sized lung adenocarcinoma.

High K-ras mutation rates in goblet-cell-type adenocarcinomas of the lungs.

Adenocarcinomas of the lungs show a variable histology. We have subclassified such lesions into five cell types: hobnail, columnar, polygonal, mixed and goblet cell types, and investigated their relationships with K-ras mutations. Codons 12, 13 and 61 of the K-ras gene in 120 surgically resected pulmonary adenocarcinomas were examined by the mutation-allele-specific amplification method. Point mutations were observed in 10% of the adenocarcinomas limited to K-ras codon 12 and the commonest base substitution (nine cases) was a G to T transversion. Of the five types, goblet cell lesions demonstrated the highest mutation index, which at 100% (6/6) was significantly different from that of all other cell types. No relationship between K-ras mutation and cigarette smoking was observed. From these findings, it appears that development of goblet-cell-type adenocarcinomas of the lung may involve different carcinogenic mechanisms from adenocarcinomas of other subtypes.

Subcutaneous sarcomas of probable neuronal origin in a transgenic mouse strain containing an albumin promoter-fused simian virus 40 large T antigen gene.

Frequent development of subcutaneous neurogenic sarcomas was observed in a hepatocellular carcinoma-producing transgenic mouse strain harboring an albumin-promoted simian virus 40 (SV40) large T antigen gene. Found unexpectedly in 19 out of 306 mice (6.2%) by 6 months of age, all the sarcomas were similar and were characterized as neurogenic on the basis of histological features including Homer-Wright type rosette formation, the presence of dense core granules of 100-200 nm diameter under the electron microscope, expression of neuron specific enolase, S-100 protein, and catecholamines, and nerve cell-like differentiation in culture in response to But2cAMP. Immunohistochemical study revealed tiny clusters of SV40 T antigen-expressing cells with neurogenic character in normal-appearing adult mouse subcutis as candidate progenitors of the sarcomas. The tumor cells strongly expressed large T antigen but did not express albumin or albumin mRNA at the detection sensitivity used. Transient transfection assay (CAT assay), however, revealed the presence of transcriptional factor(s) acting on the albumin promoter in tumor cells. Thus, the present investigation suggested the presence of specifically differentiated neurogenic cells in the mouse subcutis with aberrant expression of the transgene.

Mucosal spreading adenocarcinoma at the hilar portion of the lung.

The first case of mucosal spreading adenocarcinoma at the hilum of the lung is presented. The patient was a 72 year old Japanese male smoker. The carcinoma was located at the right main bronchus with involvement of the apical, posterior and anterior segmental bronchi. The tumor consisted of stratified oval or polygonal cells and signet ring cells spreading along the bronchial mucosa in an in situ fashion with extension down the bronchial gland ducts and acini. Only a small micro-invasive focus not extending beyond the bronchial cartilage was seen. Immunohistochemically, the tumor was positive for lysozyme but negative for lactoferrin and PE-10 indicating that this tumor was possibly showing goblet cell differentiation.

Immunophenotypic and molecular analysis of a case of lymphocytic interstitial pneumonia.

A case of lymphocytic interstitial pneumonia was studied immunophenotypically and with molecular methods in order to clarify its lymphocytic clonality. The patient, a 43 year old Japanese female, underwent lobectomy for a suspected malignant lymphoma as no clear diagnosis could be made from the biopsy specimen. An ill-demarcated, yellowish and elastic firm lesion measuring 60 x 35 x 20 mm in size was located in the peripheral part of the middle lobe of the right lung. Histologically, the alveolar, peribronchial-vascular and subpleural interstitia within the lesion were thickened markedly with severe cellular infiltration largely composed of small lymphocytes with germinal centers. Immunostaining revealed immunoglobulin (Ig) kappa and Ig lambda-bearing cells to be evenly distributed, suggestive of polyspecificity. Immunoglobulin gene analysis further demonstrated the unrearranged germ-line DNA but no rearranged band. These results strongly indicated a reactive process rather than a neoplastic nature for the lesion.