Biomedical subjects

David G Beer

Publications and source records attributed to David G Beer.

42 records · Page 3Linked to original sources

PubMed2002

Discordant protein and mRNA expression in lung adenocarcinomas.

The relationship between gene expression measured at the mRNA level and the corresponding protein level is not well characterized in human cancer. In this study, we compared mRNA and protein expression for a cohort of genes in the same lung adenocarcinomas. The abundance of 165 protein spots representing 98 individual genes was analyzed in 76 lung adenocarcinomas and nine non-neoplastic lung tissues using two-dimensional polyacrylamide gel electrophoresis. Specific polypeptides were identified using matrix-assisted laser desorption/ionization mass spectrometry. For the same 85 samples, mRNA levels were determined using oligonucleotide microarrays, allowing a comparative analysis of mRNA and protein expression among the 165 protein spots. Twenty-eight of the 165 protein spots (17%) or 21 of 98 genes (21.4%) had a statistically significant correlation between protein and mRNA expression (r > 0.2445; p < 0.05); however, among all 165 proteins the correlation coefficient values (r) ranged from -0.467 to 0.442. Correlation coefficient values were not related to protein abundance. Further, no significant correlation between mRNA and protein expression was found (r = -0.025) if the average levels of mRNA or protein among all samples were applied across the 165 protein spots (98 genes). The mRNA/protein correlation coefficient also varied among proteins with multiple isoforms, indicating potentially separate isoform-specific mechanisms for the regulation of protein abundance. Among the 21 genes with a significant correlation between mRNA and protein, five genes differed significantly between stage I and stage III lung adenocarcinomas. Using a quantitative analysis of mRNA and protein expression within the same lung adenocarcinomas, we showed that only a subset of the proteins exhibited a significant correlation with mRNA abundance.

Adenocarcinoma↗

PubMed2002

Proteomic analysis of lung adenocarcinoma: identification of a highly expressed set of proteins in tumors.

PURPOSE: The goal of this study was to identify potential protein markers in lung adenocarcinomas. EXPERIMENTAL DESIGN: A series of 93 lung adenocarcinomas (64 stage I and 29 stage III) and 10 uninvolved lung samples were examined for quantitative differences in protein expression using two-dimensional PAGE. Candidate proteins were identified using matrix-assisted laser desorption/ionization mass spectrometry or peptide sequencing. The levels of the individual isoforms of nine proteins found to be overexpressed in the lung tumors were examined. Potential mechanisms for overexpression were examined by comparing mRNA expression levels, assessed using oligonucleotide arrays, to the protein values in the same samples. RESULTS: Antioxidant enzyme AOE372, ATP synthase subunit d (ATP5D), beta1,4-galactosyltransferase, cytosolic inorganic pyrophosphatase, glucose-regulated M(r) 58,000 protein, glutathione-S-transferase M4, prolyl 4-hydroxylase beta subunit, triosephosphate isomerase, and ubiquitin thiolesterase (UCHL1) were identified as being significantly overexpressed in lung adenocarcinomas. The expression of these proteins was increased from 1.4- to 10.6-fold as compared with uninvolved lung tissue. The expression of the individual protein isoforms was correlated with 10 clinicopathological variables as well as with each gene's mRNA level in the same sample. Both isoforms of glucose-regulated M(r) 58,000 protein were found to be significantly correlated with their mRNA expression profiles (P < 0.05), indicating that increased transcription likely underlies the increased expression of these proteins. CONCLUSIONS: Two-dimensional PAGE and mass spectrometry can identify proteins showing increased expression in lung adenocarcinoma. The association of specific isoforms of these proteins with clinical variables and understanding the regulation of their expression will aid in determination of their potential use as biomarkers in this cancer.

Adenocarcinoma↗

PubMed2002

RANTES expression is a predictor of survival in stage I lung adenocarcinoma.

PURPOSE: The presence of an active lymphocytic response (ALR) in non-small cell lung cancer (NSCLC) tumors has previously been associated with a more favorable prognosis. The purpose of this study was to identify differences in global gene expression profiles between stage I NSCLC tumors with ALR (ALR+) and those without ALR (ALR-). EXPERIMENTAL DESIGN: Sixty-three stage I lung adenocarcinomas were analyzed for gene expression using Affymetrix oligonucleotide microarrays. Tumors were stratified into ALR+ and ALR- groups and compared for statistically significant differences in gene expression. Identified candidate genes were validated using both ELISA and immunohistochemistry. Follow-up data for these patients were collected and used to assess patient prognosis. RESULTS: Of the 63 tumors studied, 27 were ALR+ and 36 were ALR-. A total of 303 genes showed significant differences in gene expression between the two populations (t test, P < 0.02). Three of the genes overexpressed by ALR+ tumors were the chemokines: small inducible cytokine A4 (MIP-1beta), RANTES, and interferon inducible protein 10 (IP-10). Immunohistochemistry analysis showed that the tumor cells expressed these cytokines. ELISA showed that MIP-1beta and RANTES were overexpressed at the protein level by ALR+ tumors. Univariate Cox proportional hazards analysis showed that RANTES was a predictor of survival in stage I lung adenocarcinomas (P = 0.002). CONCLUSION: When tested in the Cox univariate proportional hazards model, RANTES expression by lung adenocarcinoma cells is a predictor of survival in stage I NSCLC patients and may be useful as a prognostic factor in lung cancer.

Adenocarcinoma↗

PubMedDate not supplied

L-type amino acid transporter-1 overexpression and melphalan sensitivity in Barrett's adenocarcinoma.

The L-type amino acid transporter-1 (LAT-1) has been associated with tumor growth. Using cDNA microarrays, overexpression of LAT-1 was found in 87.5% (7/8) of esophageal adenocarcinomas relative to 12 Barrett's samples (33% metaplasia and 66% dysplasia) and was confirmed in 100% (28/28) of Barrett's adenocarcinomas by quantitative reverse transcription polymerase chain reaction. Immunohistochemistry revealed LAT-1 staining in 37.5% (24/64) of esophageal adenocarcinomas on tissue microarray. LAT-1 also transports the amino acid-related chemotherapeutic agent, melphalan. Two esophageal adenocarcinoma and one esophageal squamous cell line, expressing LAT-1 on Western blot analysis, were sensitive to therapeutic doses of melphalan (P <.001). Simultaneous treatment with the competitive inhibitor, BCH [2-aminobicyclo-(2,1,1)-heptane-2-carboxylic acid], decreased sensitivity to melphalan (P <.05). In addition, confluent esophageal squamous cultures were less sensitive to melphalan (P <.001) and had a decrease in LAT-1 protein expression. Tumors from two esophageal adenocarcinoma cell lines grown in nude mice retained LAT-1 mRNA expression. These results demonstrate that LAT-1 is highly expressed in a subset of esophageal adenocarcinomas and that Barrett's adenocarcinoma cell lines expressing LAT-1 are sensitive to melphalan. LAT-1 expression is also retained in cell lines grown in nude mice providing a model to evaluate melphalan as a chemotherapeutic agent against esophageal adenocarcinomas expressing LAT-1.

Adenocarcinoma↗

PubMedDate not supplied

Proteomic analysis of cytokeratin isoforms uncovers association with survival in lung adenocarcinoma.

Cytokeratins (CK) are intermediate filaments whose expression is often altered in epithelial cancer. Systematic identification of lung adenocarcinoma proteins using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry has uncovered numerous CK isoforms. In this study, 93 lung adenocarcinomas (64 stage I and 29 stage III) and 10 uninvolved lung samples were quantitatively examined for protein expression. Fourteen of 21 isoforms of CK 7, 8, 18, and 19 occurred at significantly higher levels (P < .05) in tumors compared to uninvolved adjacent tissue. Specific isoforms of the four types of CK identified correlated with either clinical outcome or individual clinical-pathological parameters. All five of the CK7 isoforms associated with patient survival represented cleavage products. Two of five CK7 isoforms (nos. 2165 and 2091), one of eight CK8 isoforms (no. 439), and one of three CK19 isoforms (no. 1955) were associated with survival and significantly correlated to their mRNA levels, suggesting that transcription underlies overexpression of these CK isoforms. Our data indicate substantial heterogeneity among CK in lung adenocarcinomas resulting from posttranslational modifications, some of which correlated with patient survival and other clinical parameters. Therefore, specific isoforms of individual CK may have utility as diagnostic or predictive markers in lung adenocarcinomas.

Adenocarcinoma↗

PubMedDate not supplied

Exisulind and CP248 induce growth inhibition and apoptosis in human esophageal adenocarcinoma and squamous carcinoma cells.

We examined the effects of exisulind (sulindac sulfone) and a potent derivative CP248 on the Barrett's esophagus (BE)-related adenocarcinoma cell lines Seg-1 and Bic-1, and on HCE7 esophageal squamous carcinoma cells. Marked growth inhibition and apoptosis occurred in all cell lines with IC50 values of 100-300 microM for exisulind and 100 nM for CP248. Bic-1 and HCE7 cells were more sensitive to the growth inhibitory properties of exisulind. Treatment of all cell lines with CP248 for 24 h increased the proportion of cells in mitosis. Exisulind had no effect on cell-cycle progression. Treatment with either compound induced rapid activation of the c-Jun NH2-terminal kinase 1 (JNK1), suggesting that JNK1 activation plays a role in the induction of apoptosis by these compounds. Only Seg-1 cells expressed a detectable basal level of cyclooxygenase-2 (cox-2), providing further evidence that cox-2 is not the critical target for the growth inhibitory and apoptotic effects of these compounds. Cellular levels of reduced glutathione (GSH) increased approximately five-fold in all cell lines after 24 h of treatment with either compound. These studies provide support for the use of exisulind in BE chemoprevention trials, and of exisulind or CP248 in the therapy of patients with esophageal carcinoma.

Adenocarcinoma↗