The current histologic classifications of gastric cancers define only carcinoids and small cell carcinomas in the neuroendocrine (NE) category. This study aimed to characterize the histologic and clinical features of high-grade gastric NE carcinomas of nonsmall cell type, tentatively named large cell neuroendocrine carcinoma (LCNEC). Tumors with histologic features suspicious of NE differentiation were selected by a histologic review of 2835 resected gastric cancers, and those with a NE phenotype in > 50% and 1% to approximately 50% tumor cells assessed by expressing chromogranin A and/or synaptophysin were defined as LCNEC and adenocarcinoma with neuroendocrine differentiation (ACNED), respectively. One hundred ninety-nine tumors were selected and of the 109 positive for chromogranin A and/or synaptophysin, 42 and 44 met the criteria for LCNEC and ACNED, respectively. Generally, LCNECs demonstrated less predominant NE morphology than carcinoids, and could be roughly divided into solid (30 cases), tubular (7 cases), and scirrhous (5 cases) subtypes with reference to their main growth pattern. The prognosis of LCNECs was significantly worse than that of conventional adenocarcinomas (P < 0.0001). Thus, this study shows that the spectrum of gastric NE tumors is broader than has previously been recognized and LCNEC is not only a distinct histopathologic entity, but also a distinct clinical entity. Furthermore, the prognosis of ACNEDs was also significantly worse than that of adenocarcinomas (P < 0.0001), and some ACNEDs might actually have been LCNECs, and survival analysis showed that > 20% positivity of NE markers could be enough to characterize LCNEC, as long as light microscopic NE morphology was present in the tumor.

Expression of cyclins A and E and cyclin-dependent kinase 2 (CDK2) was examined immunohistochemically in 190 cases of human lung carcinoma. Cyclin A and CDK2 were expressed in the majority of squamous cell carcinomas , small cell carcinomas, and large cell carcinomas , but in significantly fewer cases of adenocarcinomas. Cyclin E was expressed in a minority of all subtypes. In particular , well differentiated cells in squamous cell carcinoma stained positively for cyclin E; in contrast , cyclin A was expressed in the nonkeratinized proliferating areas of the tumor nests. Immunoblotting revealed that all these proteins were expressed at higher levels in tumor tissues than in adjacent normal tissues. Immunoprecipitation also revealed higher levels of cyclin A and cyclin E associated with CDK2 in tumor tissues. Furthermore , tumor tissues which exhibited higher cyclin A and CDK2 expression also had higher CDK2 kinase activity. However , cyclin E-associated kinase activity was barely detectable even in tumor samples exhibiting higher cyclin E expression. Consistent with these data , elevated expression of cyclin A correlated to shorter survival periods in contrast to expression of cyclin E , which correlated to longer survival periods. These results suggest that in human lung carcinomas, elevated expression of active cyclin A-CDK2 complexes with associated higher CDK2 kinase activity is critical for promoting cell cycle progression and unrestrained proliferation of tumor cells and can be a predictive marker for patients' prognosis. Cell proliferation is ultimately dependent on cell cycle control and the decision to continue to proliferate is made mainly during G 1 phase as a result of the activities of G 1 cyclins and CDK complexes. 1-8 Cyclin D is expressed initially in the G 1 phase and associated kinase activity, manifested mainly by CDK4, oscillates from mid-G 1 . Cyclin E is expressed periodically, assembling with CDK2 and inducing maximum kinase activity at the G 1 /S transition. 7,8 Subsequently cyclin A is expressed and is thought to be required, in association with CDK2 and CDC2 (cell-cycle division 2), for progression through the S phase and the G 2 /M transition, respectively. 9 Among these cyclins only cyclin D1 has been identified as a proto-oncogene, designated PRAD1. It is overexpressed in lung, breast, gastric, and esophageal carcinomas at a frequency ranging from 13 to 60% with or without amplification of the 11q13 region. 10 -15 Amplification and/or overexpression of cyclin E has also been reported in colorectal and breast carcinomas. 16 -21 Overexpression of cyclin A has been reported in several cases of cultured cell lines from alveolar epithelial cells of the lung. 22 In addition, the cyclin A gene was found to be the unique insertion site of hepatitis B virus (HBV) in one clonal hepatoma. Cyclin A may thus play a role in the continuous proliferation of liver cells and ultimately in the pathogenesis of hepatocellular carcinoma. 23,24 Based on these observations cyclins and CDKs are simply belie...

To investigate the frequency of bcl-2 oncogene protein expression in small cell lung carcinoma (SCLC), immunohistochemical staining with a mouse-anti-human monoclonal antibody, bcl-2/124, was carried out on 60 formalin-fixed, paraffin-embedded SCLC samples obtained from surgical biopsy, and autopsy cases. bcl-2 protein was detected in 54 out of the 60 SCLCs. In 47 cases, more than half of the tumour cells stained positively. The staining intensity of the tumour cells was comparable to that of infiltrating lymphocytes in 37 cases, but varied from area to area and even from cell to cell. Negative data in six cases were found to be due to unsuitable fixation or embedding procedures rather than the absence of the antigen. bcl-2 oncogene protein may thus be expressed in most if not all SCLCs. bcl-2 may have potential diagnostic and therapeutic importance in SCLCs and non-SCLCs. Previous cytogenetic and molecular genetic analyses indicate that SCLCs carry a number of chromosomal abnormalities and it would follow from the present results that the abnormal expression of bcl-2 may also play a role in the pathogenesis of SCLC, by increasing tumour mass through inhibition of apoptosis as previously proposed. The diagnostic, prognostic, and therapeutic implications of these findings should be studied in greater detail.

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Gefitinib is dramatically effective for nonsmall cell lung cancers (NSCLCs) with activating mutations of the epidermal growth factor receptor (EGFR) gene, but these tumors eventually develop drug resistance, attributable to a secondary T790M mutation or acquired MET amplification in some relapsed tumors. We analyzed EGFR mutations in matched pre-and post-therapeutic tumors of 6 gefitinib-responding lung cancers. With conventional PCR-based sequencing, classic mutations were detected in pretreatment samples of each case. The same mutations were readily confirmed in treated lesions of 4 cases, but were absent in those of Cases 1 and 2. Subsequent mutant-enriched peptide-nucleic-acidmediated PCR clamping and subcloning assays detected the mutation in minor cells of treated lesions of Case 1, but still failed to detect a mutation in Case 2. We thus performed microdissectionbased cell cluster mutation analysis of pretreatment tumors, and found that 3, including the first 2, concurrently contained tumor cells with either mutant or wild-type EGFR, although the latter was only a minor fraction. These findings suggest that some NSCLCs are genetically heterogeneous with regard to EGFR mutations; gefitinib-sensitive mutants decrease or vanish while wild clones selectively survive with gefitinib treatment. In addition, T790M was detected in a small fraction of treated lesions of 3 cases, and MET amplification was revealed in 3 treated tumors of Case 2. Thus, our results suggest that multiple mechanisms underlie acquired gefitinib resistance, and selection on a background of EGFR genetic heterogeneity also contributes to acquisition of resistance in a proportion of NSCLCs. ' 2008 Wiley-Liss, Inc.Key words: nonsmall cell lung carcinoma; EGFR; tyrosine kinase inhibitor; gefitinib; acquired drug resistance Gefitinib (Iressa) and erlotinib (Tarceva), 2 small-molecule tyrosine kinase inhibitors (TKI), have been developed to selectively inhibit the epidermal growth factor receptor (EGFR) kinase by targeting its ATP-binding site. Initial phase II trials have shown that 20% of nonsmall cell lung cancer (NSCLC) patients respond dramatically to gefitinib and erlotinib.1,2 The striking clinical responses were subsequently shown to be associated with somatic activating mutations consisting mainly of small in-frame deletions and missense substitutions in the tyrosine kinase domain of the EGFR gene, 3,4 which result in enhanced EGFR autophosphorylation and consequent activation of downstream signaling proteins. This association was further confirmed by subsequent in vivo as well as in vitro studies. [5][6][7][8][9][10][11][12][13][14] Currently, the clarification of mechanisms underlying acquired TKI resistance is an important issue of clinical relevance because the vast majority of NSCLCs that initially respond to gefitinib or erlotinib eventually became resistant to the drugs. The acquired TKI resistance in some relapsed NSCLCs has been reported to be associated with the acquisition of a secondary EGFR mutation, T790M, which results in ...

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To elucidate the mechanism of tumor extension in human pulmonary adenocarcinoma , we immunohistochemically investigated the expression of cell cycle regulator proteins in 54 small adenocarcinomas less than 3 cm in diameter. The Ki-67-labeling index was significantly higher in the periphery of the tumor nodule than in the center. This proliferative potential correlated well with coexpression of cdk2 and cyclin A. p27 , one of the cdk inhibitors , was highly expressed in normal bronchial epithelial cells. Peripherally located tumor cells expressed p27 at an intermediate level , but at a higher frequency and level than those in the center. Expression of p21 was also predominant in the periphery. Furthermore , the expression patterns of p21 and p27 were reciprocal. Adenocarcinoma is the most common histological subtype of lung carcinoma and its incidence is increasing.